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Sample records for chemical loop experimental

  1. Experimental validation of packed bed chemical-looping combustion

    NARCIS (Netherlands)

    Noorman, S.; van Sint Annaland, M.; Kuipers, J.A.M.

    2010-01-01

    Chemical-looping combustion has emerged as a promising alternative technology, intrinsically integrating CO2 capture in power production. A novel reactor concept based on dynamically operated packed beds has been proposed [Noorman, S., van Sint Annaland, M., Kuipers, J.A.M., 2007. Packed bed reactor

  2. Experimental investigation of the chemical looping method on a 1 MW pilot plant

    International Nuclear Information System (INIS)

    Orth, Matthias

    2014-01-01

    Attempting to counteract the consequences of climate change, leading industrial nations have agreed on reducing their CO 2 emissions significantly. To reach these reduction goals, it is essential to reduce the CO 2 emissions in the field of energy conversion. This PHD thesis covers the field of chemical looping combustion, a technology that uses fossil fuels for energy conversion with inherent capture of CO 2 . Since the research regarding chemical looping had so far focused mainly on lab scale or small scale experiments, a 1 MW pilot plant has been erected at Technische Universitaet Darmstadt in order to investigate the process in a semi-industrial scale and to check the process efficiency with commercially usable equipment. This pilot consists of two interconnected fluidized bed reactors and has an overall height of more than 11 m. In this thesis, some experiments with ilmenite - used as the oxygen carrier - are explained. Furthermore, the design, erection and commissioning of the pilot plant are presented as well as the results of the first test campaigns. The evaluation of the latter proves that the process can be handled in the design configuration and that CO 2 can be safely captured in a pilot plant of this scale.

  3. Experimental investigation of the chemical looping method on a 1 MW pilot plant; Experimentelle Untersuchung des Chemical Looping Verfahrens an einer 1 MW Versuchsanlage

    Energy Technology Data Exchange (ETDEWEB)

    Orth, Matthias

    2014-08-27

    Attempting to counteract the consequences of climate change, leading industrial nations have agreed on reducing their CO{sub 2} emissions significantly. To reach these reduction goals, it is essential to reduce the CO{sub 2} emissions in the field of energy conversion. This PHD thesis covers the field of chemical looping combustion, a technology that uses fossil fuels for energy conversion with inherent capture of CO{sub 2}. Since the research regarding chemical looping had so far focused mainly on lab scale or small scale experiments, a 1 MW pilot plant has been erected at Technische Universitaet Darmstadt in order to investigate the process in a semi-industrial scale and to check the process efficiency with commercially usable equipment. This pilot consists of two interconnected fluidized bed reactors and has an overall height of more than 11 m. In this thesis, some experiments with ilmenite - used as the oxygen carrier - are explained. Furthermore, the design, erection and commissioning of the pilot plant are presented as well as the results of the first test campaigns. The evaluation of the latter proves that the process can be handled in the design configuration and that CO{sub 2} can be safely captured in a pilot plant of this scale.

  4. Rational Design of Mixed-Metal Oxides for Chemical Looping Combustion of Coal via Coupled Computational-Experimental Studies

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Amit; Li, Fanxing; Santiso, Erik

    2017-09-18

    Energy and global climate change are two grand challenges to the modern society. An urgent need exists for development of clean and efficient energy conversion processes. The chemical looping strategy, which utilizes regenerable oxygen carriers (OCs) to indirectly convert carbonaceous fuels via redox reactions, is considered to be one of the more promising approaches for CO2 capture by the U.S. Department of Energy (USDOE). To date, most long-term chemical looping operations were conducted using gaseous fuels, even though direct conversion of coal is more desirable from both economics and CO2 capture viewpoints. The main challenges for direct coal conversion reside in the stringent requirements on oxygen carrier performances. In addition, coal char and volatile compounds are more challenging to convert than gaseous fuels. A promising approach for direct conversion of coal is the so called chemical looping with oxygen uncoupling (CLOU) technique. In the CLOU process, a metal oxide that decomposes at the looping temperature, and releases oxygen to the gas phase is used as the OC. The overarching objective of this project was to discover the fundamental principles for rational design and optimization of oxygen carriers (OC) in coal chemical looping combustion (CLC) processes. It directly addresses Topic Area B of the funding opportunity announcement (FOA) in terms of “predictive description of the phase behavior and mechanical properties” of “mixed metal oxide” based OCs and rational development of new OC materials with superior functionality. This was achieved through studies exploring i) iron-containing mixed-oxide composites as oxygen carriers for CLOU, ii) Ca1-xAxMnO3-δ (A = Sr and Ba) as oxygen carriers for CLOU, iii) CaMn1-xBxO3-δ (B=Al, V, Fe, Co, and Ni) as oxygen carrier for CLOU and iv) vacancy creation energy in Mn-containing perovskites as an indicator chemical looping with oxygen uncoupling.

  5. High pressure experimental water loop

    International Nuclear Information System (INIS)

    Grenon, M.

    1958-01-01

    A high pressure experimental water loop has been made for studying the detection and evolution of cladding failure in a pressurized reactor. The loop has been designed for a maximum temperature of 360 deg. C, a maximum of 160 kg/cm 2 and flow rates up to 5 m 3 /h. The entire loop consists of several parts: a main circuit with a canned rotor circulation pump, steam pressurizer, heating tubes, two hydro-cyclones (one de-gasser and one decanter) and one tubular heat exchanger; a continuous purification loop, connected in parallel, comprising pressure reducing valves and resin pots which also allow studies of the stability of resins under pressure, temperature and radiation; following the gas separator is a gas loop for studying the recombination of the radiolytic gases in the steam phase. The preceding circuits, as well as others, return to a low pressure storage circuit. The cold water of the low pressure storage flask is continuously reintroduced into the high pressure main circuit by means of a return pump at a maximum head of 160 kg /cm 2 , and adjusted to the pressurizer level. This loop is also a testing bench for the tight high pressure apparatus. The circulating pump and the connecting flanges (Oak Ridge type) are water-tight. The feed pump and the pressure reducing valves are not; the un-tight ones have a system of leak recovery. To permanently check the tightness the circuit has been fitted with a leak detection system (similar to the HRT one). (author) [fr

  6. Hybrid Combustion-Gasification Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Herbert Andrus; Gregory Burns; John Chiu; Gregory Lijedahl; Peter Stromberg; Paul Thibeault

    2009-01-07

    For the past several years Alstom Power Inc. (Alstom), a leading world-wide power system manufacturer and supplier, has been in the initial stages of developing an entirely new, ultra-clean, low cost, high efficiency power plant for the global power market. This new power plant concept is based on a hybrid combustion-gasification process utilizing high temperature chemical and thermal looping technology The process consists of the oxidation, reduction, carbonation, and calcination of calcium-based compounds, which chemically react with coal, biomass, or opportunity fuels in two chemical loops and one thermal loop. The chemical and thermal looping technology can be alternatively configured as (i) a combustion-based steam power plant with CO{sub 2} capture, (ii) a hybrid combustion-gasification process producing a syngas for gas turbines or fuel cells, or (iii) an integrated hybrid combustion-gasification process producing hydrogen for gas turbines, fuel cells or other hydrogen based applications while also producing a separate stream of CO{sub 2} for use or sequestration. In its most advanced configuration, this new concept offers the promise to become the technology link from today's Rankine cycle steam power plants to tomorrow's advanced energy plants. The objective of this work is to develop and verify the high temperature chemical and thermal looping process concept at a small-scale pilot facility in order to enable AL to design, construct and demonstrate a pre-commercial, prototype version of this advanced system. In support of this objective, Alstom and DOE started a multi-year program, under this contract. Before the contract started, in a preliminary phase (Phase 0) Alstom funded and built the required small-scale pilot facility (Process Development Unit, PDU) at its Power Plant Laboratories in Windsor, Connecticut. Construction was completed in calendar year 2003. The objective for Phase I was to develop the indirect combustion loop with CO{sub 2

  7. Chemical Looping Combustion Reactions and Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, Adel; Lighty, JoAnn; Smith, Philip; Whitty, Kevin; Eyring, Edward; Sahir, Asad; Alvarez, Milo; Hradisky, Michael; Clayton, Chris; Konya, Gabor; Baracki, Richard; Kelly, Kerry

    2014-03-01

    , they performed a sensitivity analysis for velocity, height and polydispersity and compared results against literature data for experimental studies of CLC beds with no reaction. Finally, they present an optimization space using simple non-reactive configurations. In Subtask 5.3, through a series of experimental studies, behavior of a variety of oxygen carriers with different loadings and manufacturing techniques was evaluated under both oxidizing and reducing conditions. The influences of temperature, degree of carrier conversion and thermodynamic driving force resulting from the difference between equilibrium and system O{sub 2} partial pressures were evaluated through several experimental campaigns, and generalized models accounting for these influences were developed to describe oxidation and oxygen release. Conversion of three solid fuels with widely ranging reactivities was studied in a small fluidized bed system, and all but the least reactive fuel (petcoke) were rapidly converted by oxygen liberated from the CLOU carrier. Attrition propensity of a variety of carriers was also studied, and the carriers produced by freeze granulation or impregnation of preformed substrates displayed the lowest rates of attrition. Subtask 5.4 focused on gathering kinetic data for a copper-based oxygen carrier to assist with modeling of a functioning chemical looping reactor. The kinetics team was also responsible for the development and analysis of supported copper oxygen carrier material.

  8. Chemical-looping combustion - status of development

    Energy Technology Data Exchange (ETDEWEB)

    Lyngfelt, Anders; Johansson, Marcus; Mattisson, Tobias

    2008-05-15

    Chemical-looping combustion (CLC) is a combustion technology with inherent separation of the greenhouse gas CO{sub 2}. The technique involves the use of a metal oxide as an oxygen carrier which transfers oxygen from combustion air to the fuel, and hence a direct contact between air and fuel is avoided. Two inter-connected fluidized beds, a fuel reactor and an air reactor, are used in the process. In the fuel reactor, the metal oxide is reduced by the reaction with the fuel and in the air reactor; the reduced metal oxide is oxidized with air. The outlet gas from the fuel reactor consists of CO{sub 2} and H{sub 2}O, and almost pure stream of CO{sub 2} is obtained when water is condensed. Considerable research has been conducted on CLC in the last years with respect to oxygen carrier development, reactor design, system efficiencies and prototype testing. In 2002 the process was a paper concept, albeit with some important but limited laboratory work on oxygen carrier particles. Today more than 600 materials have been tested and the technique has been successfully demonstrated in chemical-looping combustors in the size range 0.3 - 50 kW, using different types of oxygen carriers based on the metals Ni, Co, Fe, Cu and Mn. The total time of operational experience is more than a thousand hours. From these tests it can be established that almost complete conversion of the fuel can be obtained and 100% CO{sub 2} capture is possible. Most work so far has been focused on gaseous fuels, but the direct application to solid fuels is also being studied. Moreover, the same principle of oxygen transfer is used in chemical-looping reforming (CLR), which involves technologies to produce hydrogen with inherent CO{sub 2} capture. This paper presents an overview of the research performed on CLC and CLR highlights the current status of the technology

  9. Geothermal Loop Experimental Facility. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1980-04-01

    Research at the Geothermal Loop Experimental Facility was successfully concluded in September 1979. In 13,000 hours of operation over a three and one half year period, the nominal 10 megawatt electrical equivalent GLEF provided the opportunity to identify problems in working with highly saline geothermal fluids and to develop solutions that could be applied to a commercial geothermal power plant producing electricity. A seven and one half year period beginning in April 1972, with early well flow testing and ending in September 1979, with the completion of extensive facility and reservoir operations is covered. During this period, the facility was designed, constructed and operated in several configurations. A comprehensive reference document, addressing or referencing documentation of all the key areas investigated is presented.

  10. Control and optimization system and method for chemical looping processes

    Science.gov (United States)

    Lou, Xinsheng; Joshi, Abhinaya; Lei, Hao

    2015-02-17

    A control system for optimizing a chemical loop system includes one or more sensors for measuring one or more parameters in a chemical loop. The sensors are disposed on or in a conduit positioned in the chemical loop. The sensors generate one or more data signals representative of an amount of solids in the conduit. The control system includes a data acquisition system in communication with the sensors and a controller in communication with the data acquisition system. The data acquisition system receives the data signals and the controller generates the control signals. The controller is in communication with one or more valves positioned in the chemical loop. The valves are configured to regulate a flow of the solids through the chemical loop.

  11. Chemical Looping Combustion Reactions and Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, Adel; Lighty, JoAnn; Smith, Philip; Whitty, Kevin; Eyring, Edward; Sahir, Asad; Alvarez, Milo; Hradisky, Michael; Clayton, Chris; Konya, Gabor; Baracki, Richard; Kelly, Kerry

    2011-07-01

    Chemical Looping Combustion (CLC) is one promising fuel-combustion technology, which can facilitate economic CO2 capture in coal-fired power plants. It employs the oxidation/reduction characteristics of a metal, or oxygen carrier, and its oxide, the oxidizing gas (typically air) and the fuel source may be kept separate. This work focused on two classes of oxygen carrier, one that merely undergoes a change in oxidation state, such as Fe3O4/Fe2O3 and one that is converted from its higher to its lower oxidation state by the release of oxygen on heating, i.e., CuO/Cu2O. This topical report discusses the results of four complementary efforts: (1) the development of process and economic models to optimize important design considerations, such as oxygen carrier circulation rate, temperature, residence time; (2) the development of high-performance simulation capabilities for fluidized beds and the collection, parameter identification, and preliminary verification/uncertainty quantification (3) the exploration of operating characteristics in the laboratory-scale bubbling bed reactor, with a focus on the oxygen carrier performance, including reactivity, oxygen carrying capacity, attrition resistance, resistance to deactivation, cost and availability (4) the identification of mechanisms and rates for the copper, cuprous oxide, and cupric oxide system using thermogravimetric analysis.

  12. Methods for the neutronic design of a Supersara experimental loop

    International Nuclear Information System (INIS)

    Casali, F.; Cepraga, D.

    1982-01-01

    This paper describes a method for the neutronic design of experimental loops irradiated in D 2 O experimental reactors, like Essor. The calculation approach concerns the definition of a Weigner-Seitz cell where the loop under examination be subjected to the same neutronic conditions as in the actual reactor

  13. Chemical looping reforming of generator gas

    Energy Technology Data Exchange (ETDEWEB)

    Mendiara, T.; Jensen, Anker; Glarborg, P.

    2010-02-15

    The main objective of this work is to investigate the carbon deposition during reforming of hydrocarbons in a Chemical Looping Reformer (CLR). This knowledge is needed to asses the viability of the CLR technology in reforming tar from biomass gasification preserving lighter hydrocarbons and minimizing the carbon formation during the process. Two different setups were used to test the reactivity of the different samples in the conditions of interest for the tar reforming process: 1) Fixed bed flow reactor (FR), and 2) Thermogravimetric analyzer (TGA). In the experiments, the gas atmosphere was switched from reducing to oxidizing atmosphere in every cycle. During the oxidizing cycle, the carrier was regenerated using a mixture of oxygen and nitrogen. Four different oxygen carriers based on nickel (Ni40 and Ni60), manganese (Mn) and ilmenite (Fe) were tested. In the tests, toluene was used to simulate the tars. The Fe and the Mn carrier reacted to a small extent with methane at the highest temperature studied, 800 degrees C. The Ni-carriers did not react at 600 degrees C at first, but they showed some reactivity after having been activated at the higher temperature. Carbon formation occurred with the Ni-carriers, more so with the Ni60 than the Ni40. Ni40, Mn and Fe were activated at the higher temperature. However, Fe showed only low capacity. Ni60 showed no capability of tar reforming. Ni40 showed a high tendency to carbon formation at 800 degrees C, but the formation could be lowered by changing some parameters. Mn formed almost no carbon. Ni40 and Mn were chosen for further studies. Carbon deposition occurred for both Ni40 and Mn, but the amount deposited for Ni40 was about 10 times bigger. Ni40 reacted with the methane and toluene only at 800 degrees C. The conversion over Mn was not as big as for toluene alone. Carbon was formed from carbon monoxide on the Ni40 carrier and on the Mn, but to a much less extent on the latter one. The presence of hydrogen decreased

  14. Dynamic response of IPEN experimental water loop

    International Nuclear Information System (INIS)

    Faya, A.J.G.; Bassel, W.S.

    1982-10-01

    A mathematical model has been developed to analyze the transient thermal response of the I.P.E.N. water loop during change of power operations. The model is capable of estimating the necessary test section power and heat exchanger mass flow rate for a given operating temperature. It can also determine the maximum heating or cooling rate to avoid thermal shocks in pipes and components. (Author) [pt

  15. Closed loop chemical systems for energy storage and transmission (chemical heat pipe). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Vakil, H.B.; Flock, J.W.

    1978-02-01

    The work documents the anlaysis of closed loop chemical systems for energy storage and transmission, commonly referred to as the Chemical Heat Pipe (CHP). Among the various chemical reaction systems and sources investigated, the two best systems were determined to be the high temperature methane/steam reforming reaction (HTCHP) coupled to a Very High Temperature Gas Cooled Reactor (VHTR) and the lower temperature, cyclohexane dehydrogenation reaction (LTCHP) coupled to existing sources such as coal or light water reactors. Solar and other developing technologies can best be coupled to the LTCHP. The preliminary economic and technical analyses show that both systems could transport heat at an incremental cost of approximately $1.50/GJ/160 km (in excess of the primary heat cost of $2.50/GJ), at system efficiencies above 80%. Solar heat can be transported at an incremental cost of $3/GJ/160 km. The use of the mixed feed evaporator concept developed in this work contributes significantly to reducing the transportation cost and increasing the efficiency of the system. The LTCHP shows the most promise of the two systems if the technical feasibility of the cyclic closed loop chemical reaction system can be established. An experimental program for establishing this feasibility is recommended. Since the VHTR is several years away from commercial demonstration and the HTCHP chemical technology is well developed, future HTCHP programs should be aimed at VHTR and interface problems.

  16. Feedback loop process for controlling inertial cavitation: experimental evidence

    Science.gov (United States)

    Inserra, Claude; Sabraoui, Abbas; Reslan, Lina; Bera, Jean-Christophe; Gilles, Bruno; Mestas, Jean-Louis

    2011-09-01

    Applications involving cavitation mechanisms, such as sonoporation, are irreproducible in the case of a fixed-intensity sonication, due to the non-stationary behavior of cavitation. We then propose to work at a fixed-cavitation level instead of under fixed-intensity sonication conditions. For this purpose a regulated cavitation generator has been developed in a stationary wave field configuration, which allows regulation of the cavitation level during sonication by modulating the applied acoustic intensity with a feedback loop based on acoustic cavitation measurements. The cavitation level indicator was quantified by the broadband spectrum noise level relative to inertial cavitation events. This generated inertial cavitation was characterized by both acoustic and chemical measurements, quantifying hydroxyl radicals produced by water sonolysis. While the cavitation level is obtained with a 40% standard deviation for fixed applied acoustic intensities in the range [0.01 3.44] W/cm2, the regulated generator reproduces the cavitation level with a standard deviation of 3%. The results show that the hydroxyl radical production is better correlated with the cavitation level setting than with the applied acoustic intensity, highlighting the fact that broadband noise is a good indicator of inertial cavitation, with greatest interest for cavitation monitoring. In summary, the regulated device generates a cavitation level that is reproducible, repeatable and stable in time. This system produces reproducible effects that allow consideration of biological applications such as sonoporation to be independent of the experimental ultrasound device, as confirmed by transfection efficiency and cell cytotoxicity studies. Thus, this feedback loop process presents interesting perspectives for monitoring and controlling in-vivo cavitation.

  17. Nonlinear model predictive control for chemical looping process

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Abhinaya; Lei, Hao; Lou, Xinsheng

    2017-08-22

    A control system for optimizing a chemical looping ("CL") plant includes a reduced order mathematical model ("ROM") that is designed by eliminating mathematical terms that have minimal effect on the outcome. A non-linear optimizer provides various inputs to the ROM and monitors the outputs to determine the optimum inputs that are then provided to the CL plant. An estimator estimates the values of various internal state variables of the CL plant. The system has one structure adapted to control a CL plant that only provides pressure measurements in the CL loops A and B, a second structure adapted to a CL plant that provides pressure measurements and solid levels in both loops A, and B, and a third structure adapted to control a CL plant that provides full information on internal state variables. A final structure provides a neural network NMPC controller to control operation of loops A and B.

  18. Experimental investigation of magnetically confined plasma loops

    Energy Technology Data Exchange (ETDEWEB)

    Tenfelde, Jan

    2012-12-11

    Arch-shaped magnetic flux tubes generated in a pulsed-power plasma experiment were investigated with a variety of diagnostics concerning their expansion properties. Specifically, the expansion velocity was of interest, which is observed as constant for a wide range of experimental parameters. An MHD transport mechanism is investigated as possible cause of a uniform arch cross section: Axial transport of poloidal magnetic flux along the plasma may cause a pinch force leading to a uniform diameter along the arch. Despite numerous experimental findings at a very similar experimental setup, no indication for the relevance of this process could be found. Instead, magnetic probe data showed that the plasma current in the apex region is constant. A constant expansion velocity was observed for considerably different experimental conditions. This included different plasma source designs with fundamentally different toroidal magnetic field topology and variation of the working gas, which lead to plasma densities lower by an order of magnitude. Inside the current channel of the arch, Alfven velocities were estimated. To this end, plasma density profiles obtained from interferometry were inverted to obtain local densities, which were in turn verified by means of Stark broadening of hydrogen Balmer lines. Furthermore, measurements of multiple components of the magnetic field of the plasma arch were performed. An estimate for the conductivity was obtained from Spitzer's formula for fully ionized plasma using electron temperatures obtained from elementary optical emission spectroscopy. From the presented data of ccd imaging, magnetic field probes, and to lesser extent, interferometry, the underlying assumption of residual plasma (and considerable plasma currents through it) below the actual arch structure is very plausible. Rough estimates of the electric field strength along the arch and results of the magnetic field measurements showed, that the detected expansion

  19. Experimental investigation of magnetically confined plasma loops

    International Nuclear Information System (INIS)

    Tenfelde, Jan

    2012-01-01

    Arch-shaped magnetic flux tubes generated in a pulsed-power plasma experiment were investigated with a variety of diagnostics concerning their expansion properties. Specifically, the expansion velocity was of interest, which is observed as constant for a wide range of experimental parameters. An MHD transport mechanism is investigated as possible cause of a uniform arch cross section: Axial transport of poloidal magnetic flux along the plasma may cause a pinch force leading to a uniform diameter along the arch. Despite numerous experimental findings at a very similar experimental setup, no indication for the relevance of this process could be found. Instead, magnetic probe data showed that the plasma current in the apex region is constant. A constant expansion velocity was observed for considerably different experimental conditions. This included different plasma source designs with fundamentally different toroidal magnetic field topology and variation of the working gas, which lead to plasma densities lower by an order of magnitude. Inside the current channel of the arch, Alfven velocities were estimated. To this end, plasma density profiles obtained from interferometry were inverted to obtain local densities, which were in turn verified by means of Stark broadening of hydrogen Balmer lines. Furthermore, measurements of multiple components of the magnetic field of the plasma arch were performed. An estimate for the conductivity was obtained from Spitzer's formula for fully ionized plasma using electron temperatures obtained from elementary optical emission spectroscopy. From the presented data of ccd imaging, magnetic field probes, and to lesser extent, interferometry, the underlying assumption of residual plasma (and considerable plasma currents through it) below the actual arch structure is very plausible. Rough estimates of the electric field strength along the arch and results of the magnetic field measurements showed, that the detected expansion

  20. Packed Bed Reactor Technology for Chemical-Looping Combustion

    NARCIS (Netherlands)

    Noorman, S.; van Sint Annaland, M.; Kuipers, J.A.M.

    2007-01-01

    Chemical-looping combustion (CLC) has emerged as an alternative for conventional power production processes to intrinsically integrate power production and CO2 capture. In this work a new reactor concept for CLC is proposed, based on dynamically operated packed bed reactors. With analytical

  1. Advancements in Development of Chemical-Looping Combustion: A Review

    Directory of Open Access Journals (Sweden)

    He Fang

    2009-01-01

    Full Text Available Chemical-looping combustion (CLC is a novel combustion technology with inherent separation of greenhouse CO2. Extensive research has been performed on CLC in the last decade with respect to oxygen carrier development, reaction kinetics, reactor design, system efficiencies, and prototype testing. Transition metal oxides, such as Ni, Fe, Cu, and Mn oxides, were reported as reactive species in the oxygen carrier particles. Ni-based oxygen carriers exhibited the best reactivity and stability during multiredox cycles. The performance of the oxygen carriers can be improved by changing preparation method or by making mixedoxides. The CLC has been demonstrated successfully in continuously operated prototype reactors based on interconnected fluidized-bed system in the size range of 0.3–50 kW. High fuel conversion rates and almost 100%  CO2 capture efficiencies were obtained. The CLC system with two interconnected fluidized-bed reactors was considered the most suitable reactor design. Development of oxygen carriers with excellent reactivity and stability is still one of the challenges for CLC in the near future. Experiences of building and operating the large-scale CLC systems are needed before this technology is used commercially. Chemical-looping reforming (CLR and chemical-looping hydrogen (CLH are novel chemical-looping techniques to produce synthesis gas and hydrogen deserving more attention and research.

  2. Tri-metallic ferrite oxygen carriers for chemical looping combustion

    Science.gov (United States)

    Siriwardane, Ranjani V.; Fan, Yueying

    2017-10-25

    The disclosure provides a tri-metallic ferrite oxygen carrier for the chemical looping combustion of carbonaceous fuels. The tri-metallic ferrite oxygen carrier comprises Cu.sub.xFe.sub.yMn.sub.zO.sub.4-.delta., where Cu.sub.xFe.sub.yMn.sub.zO.sub.4-.delta. is a chemical composition. Generally, 0.5.ltoreq.x.ltoreq.2.0, 0.2.ltoreq.y.ltoreq.2.5, and 0.2.ltoreq.z.ltoreq.2.5, and in some embodiments, 0.8.ltoreq.x.ltoreq.1.2, y.ltoreq.1.2, and z.gtoreq.0.8. The tri-metallic ferrite oxygen carrier may be used in various applications for the combustion of carbonaceous fuels, including as an oxygen carrier for chemical looping combustion.

  3. Feasibility study of sulfates as oxygen carriers for chemical looping processes

    Directory of Open Access Journals (Sweden)

    Ganesh Kale

    2012-12-01

    Full Text Available The operational feasibility temperature range of chemical looping combustion (CLC and chemical looping reforming (CLR of the fuels methane, propane, iso-octane and ethanol was explored using the common sulphates

  4. Comparison of oxygen carriers for chemical-looping combustion

    Directory of Open Access Journals (Sweden)

    Johansson Marcus

    2006-01-01

    Full Text Available Chemical-looping combustion is a combustion technology with inherent separation of the greenhouse gas CO2. This technique involves combustion of fossil fuels by means of an oxygen carrier which transfers oxygen from the air to the fuel. In this manner a decrease in efficiency is avoided for the energy demanding separation of CO2 from the rest of the flue gases. Results from fifty oxygen carriers based on iron-, manganese- and nickel oxides on different inert materials are compared. The particles were prepared using freeze granulation, sintered at different temperatures and sieved to a size 125-180 mm. To simulate the environment the particles would be exposed to in a chemical-looping combustor, reactivity tests under alternating oxidizing and reducing conditions were performed in a laboratory fluidized bed-reactor of quartz. Reduction was performed in 50% CH4/50% H2O while the oxidation was carried out in 5% O2 in nitrogen. In general nickel particles are the most reactive, followed by manganese. Iron particles are harder but have a lower reactivity. An increase in sintering temperatures normally leads to an increase in strength and decrease in reactivity. Several particles investigated display a combination of high reactivity and strength as well as good fluidization behavior, and are feasible for use as oxygen carriers in chemical-looping combustion.

  5. Chemical Looping Combustion of Methane: A Technology Development View

    Directory of Open Access Journals (Sweden)

    Rutuja Bhoje

    2013-01-01

    Full Text Available Methane is a reliable and an abundantly available energy source occurring in nature as natural gas, biogas, landfill gas, and so forth. Clean energy generation using methane can be accomplished by using chemical looping combustion. This theoretical study for chemical looping combustion of methane was done to consider some key technology development points to help the process engineer choose the right oxygen carrier and process conditions. Combined maximum product (H2O + CO2 generation, weight of the oxygen carrier, net enthalpy of CLC process, byproduct formation, CO2 emission from the air reactor, and net energy obtainable per unit weight (gram of oxygen carrier in chemical looping combustion can be important parameters for CLC operation. Carbon formed in the fuel reactor was oxidised in the air reactor and that increased the net energy obtainable from the CLC process but resulted in CO2 emission from the air reactor. Use of CaSO4 as oxygen carrier generated maximum energy (−5.3657 kJ, 800°C per gram of oxygen carrier used in the CLC process and was found to be the best oxygen carrier for methane CLC. Such a model study can be useful to identify the potential oxygen carriers for different fuel CLC systems.

  6. Chemical looping combustion. Fuel conversion with inherent CO2 capture

    Energy Technology Data Exchange (ETDEWEB)

    Brandvoll, Oeyvind

    2005-07-01

    Chemical looping combustion (CLC) is a new concept for fuel energy conversion with CO2 capture. In CLC, fuel combustion is split into separate reduction and oxidation processes, in which a solid carrier is reduced and oxidized, respectively. The carrier is continuously recirculated between the two vessels, and hence direct contact between air and fuel is avoided. As a result, a stoichiometric amount of oxygen is transferred to the fuel by a regenerable solid intermediate, and CLC is thus a variant of oxy-fuel combustion. In principle, pure CO2 can be obtained from the reduction exhaust by condensation of the produced water vapour. The thermodynamic potential and feasibility of CLC has been studied by means of process simulations and experimental studies of oxygen carriers. Process simulations have focused on parameter sensitivity studies of CLC implemented in 3 power cycles; CLC-Combined Cycle, CLC-Humid Air Turbine and CLC-Integrated Steam Generation. Simulations indicate that overall fuel conversion ratio, oxidation temperature and operating pressure are among the most important process parameters in CLC. A promising thermodynamic potential of CLC has been found, with efficiencies comparable to, - or better than existing technologies for CO2 capture. The proposed oxygen carrier nickel oxide on nickel spinel (NiONiAl) has been studied in reduction with hydrogen, methane and methane/steam as well as oxidation with dry air. It has been found that at atmospheric pressure and temperatures above 600 deg C, solid reduction with dry methane occurs with overall fuel conversion of 92%. Steam methane reforming is observed along with methane cracking as side reactions, yielding an overall selectivity of 90% with regard to solid reduction. If steam is added to the reactant fuel, coking can be avoided. A methodology for long-term investigation of solid chemical activity in a batch reactor is proposed. The method is based on time variables for oxidation. The results for Ni

  7. Chemical-Looping Combustion and Gasification of Coals and Oxygen Carrier Development: A Brief Review

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2015-09-01

    Full Text Available Chemical-looping technology is one of the promising CO2 capture technologies. It generates a CO2 enriched flue gas, which will greatly benefit CO2 capture, utilization or sequestration. Both chemical-looping combustion (CLC and chemical-looping gasification (CLG have the potential to be used to generate power, chemicals, and liquid fuels. Chemical-looping is an oxygen transporting process using oxygen carriers. Recently, attention has focused on solid fuels such as coal. Coal chemical-looping reactions are more complicated than gaseous fuels due to coal properties (like mineral matter and the complex reaction pathways involving solid fuels. The mineral matter/ash and sulfur in coal may affect the activity of oxygen carriers. Oxygen carriers are the key issue in chemical-looping processes. Thermogravimetric analysis (TGA has been widely used for the development of oxygen carriers (e.g., oxide reactivity. Two proposed processes for the CLC of solid fuels are in-situ Gasification Chemical-Looping Combustion (iG-CLC and Chemical-Looping with Oxygen Uncoupling (CLOU. The objectives of this review are to discuss various chemical-looping processes with coal, summarize TGA applications in oxygen carrier development, and outline the major challenges associated with coal chemical-looping in iG-CLC and CLOU.

  8. Chemical looping reactor system design double loop circulating fluidized bed (DLCFB)

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    Chemical looping combustion (CLC) is continuously gaining more importance among the carbon capture and storage (CCS) technologies. It is an unmixed combustion process which takes place in two steps. An effective way to realize CLC is to use two interconnected fluidized beds and a metallic powder circulating among them, acting as oxygen carrier. The metallic powder oxidizes at high temperature in one of the two reactors, the air reactor (AR). It reacts in a highly exothermic reaction with the oxygen of the injected fluidising air. Afterwards the particles are sent to the other reactor where the fuel is injected, the fuel reactor (FR). There, they transport heat and oxygen necessary for the reaction with the injected fuel to take place. At high temperatures, the particle's oxygen reacts with the fuel producing Co2 and steam, and the particles are ready to start the loop again. The overall reaction, the sum of the enthalpy changes of the oxygen carrier oxidation and reduction reactions, is the same as for the conventional combustion. Two are the key features, which make CLC promising both for costs and capture efficiency. First, the high inherent irreversibility of the conventional combustion is avoided because the energy is utilized stepwise. Second, the Co2 is intrinsically separated within the process; so there is in principle no need either of extra carbon capture devices or of expensive air separation units to produce oxygen for oxy-combustion. A lot of effort is taking place worldwide on the development of new chemical looping oxygen carrier particles, reactor systems and processes. The current work is focused on the reactor system: a new design is presented, for the construction of an atmospheric 150kWth prototype working with gaseous fuel and possibly with inexpensive oxygen carriers derived from industrial by-products or natural minerals. It consists of two circulating fluidized beds capable to operate in fast fluidization regime; this will increase the

  9. Carbon Capture via Chemical-Looping Combustion and Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Marcus; Mattisson, Tobias; Ryden, Magnus; Lyngfelt, Anders

    2006-10-15

    Chemical-looping combustion (CLC) is a combustion technology with inherent separation of the greenhouse gas CO{sub 2}. The technique involves the use of a metal oxide as an oxygen carrier which transfers oxygen from combustion air to the fuel, and hence a direct contact between air and fuel is avoided. Two inter-connected fluidized beds, a fuel reactor and an air reactor, are used in the process. In the fuel reactor, the metal oxide is reduced by the reaction with the fuel and in the air reactor; the reduced metal oxide is oxidized with air. The outlet gas from the fuel reactor consists of CO{sub 2} and H{sub 2}O, and almost pure stream of CO{sub 2} is obtained when water is condensed. Considerable research has been conducted on CLC in the last decade with respect to oxygen carrier development, reactor design, system efficiencies and prototype testing. The technique has been demonstrated successfully with both natural gas and syngas as fuel in continuous prototype reactors based on interconnected fluidized beds within the size range 0.3 - 50 kW, using different types of oxygen carriers based on the metals Ni, Co, Fe, Cu and Mn. From these tests it can be established that almost complete conversion of the fuel can be obtained and 100% CO{sub 2} capture is possible. Further, two different types of chemical-looping reforming (CLR) have been presented in recent years. CLR is a technology to produce hydrogen with inherent CO{sub 2} capture. This paper presents an overview of the research performed on CLC and CLR highlights the current status of the technology.

  10. Geothermal Loop Experimental Facility. Quarterly report, October-December 1978

    Energy Technology Data Exchange (ETDEWEB)

    Anastas, G.; Bischoff, W.S.; Bishop, H.K.

    1979-01-01

    The Geothermal Loop Experimental Facility (GLEF) was modified in April 1978 from a four stage flash/binary process to a two stage cycle for the extraction of energy from a high temperature, high salinity, liquid-dominated resource. The overhaul and cleaning during October and pigging problems which led to a limited shutdown in December are discussed. Reservoir assessment, including production and injection wells, are discussed. Results of tests that were accomplished are included. Laboratory data obtained for steam, brine, binary and cooling water, and scale are indicated. Any equipment that required repairs or modifications to equipment and the clarifier/media filter are discussed. The status of the feasibility and surge studies is covered. (MHR)

  11. Geothermal Loop Experimental Facility. Quarterly report, April--June 1978

    Energy Technology Data Exchange (ETDEWEB)

    Bischoff, W.S.; Bishop, H.K.; Cooney, C.S.; Hanenburg, W.H.; Hoaglin, G.J.; Jacobson, W.O.; Mulliner, D.K.; Newell, D.G.; Swanson, C.R.

    1978-07-01

    The Geothermal Loop Experimental Facility (GLEF) was modified to use a two stage flash process with two parallel flash trains for the extraction of energy from a high temperature, high salinity, liquid-dominated resource. Since plant start-up in May 1976, a substantial amount of information has been obtained on the operation of the plant, components, brine and steam composition, production and injection wells, and the potential of the Niland Reservoir. The general operation and accomplishments of the GLEF during the period April 1978 through June 1978 are discussed. The GLEF underwent a major redesign. Modifications and inspections of various GLEF equipment and systems are also discussed. Information about the production and injection wells flow testing and instrumentation are discussed. Information regarding coatings and linings for valves and piping is included. In the Chemistry Section there is a wide range of data taken from Brine, Steam, Scale, Binary, Condensate, and Cooling Water Systems.

  12. An investigation of synthetic fuel production via chemical looping.

    Science.gov (United States)

    Zeman, Frank; Castaldi, Marco

    2008-04-15

    Producing liquid hydrocarbon fuels with a reduced greenhouse gas emissions profile would ease the transition to a carbon-neutral energy sector with the transportation industry being the immediate beneficiary followed by the power industry. Revolutionary solutions in transportation, such as electricity and hydrogen, depend on the deployment of carbon capture and storage technologies and/or renewable energy systems. Additionally, high oil prices may increase the development of unconventional sources, such as tar sands, that have a higher emissions profile. One process that is gaining interest is a system for producing reduced carbon fuels though chemical looping technologies. An investigation of the implications of such a process using methane and carbon dioxide that is reformed to yield methanol has been done. An important aspect of the investigation is the use of off-the-shelf technologies to achieve the results. The ability of the process to yield reduced emissions fuels depends on the source for the feed and process heat. For the range of conditions considered, the emissions profile of methanol produced in this method varies from 0.475 to 1.645 moles carbon dioxide per mole methanol. The upper bound can be lowered to 0.750 by applying CCS and/ or using nonfossil heat sources for the reforming. The process provides an initial pathway to incorporate CO2 into fuels independent of electrolytic hydrogen or developments in other sectors of the economy.

  13. Natural Ores as Oxygen Carriers in Chemical Looping Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Hanjing; Siriwardane, Ranjani; Simonyi, Thomas; Poston, James

    2013-08-01

    Chemical looping combustion (CLC) is a combustion technology that utilizes oxygen from oxygen carriers (OC), such as metal oxides, instead of air to combust fuels. The use of natural minerals as oxygen carriers has advantages, such as lower cost and availability. Eight materials, based on copper or iron oxides, were selected for screening tests of CLC processes using coal and methane as fuels. Thermogravimetric experiments and bench-scale fixed-bed reactor tests were conducted to investigate the oxygen transfer capacity, reaction kinetics, and stability during cyclic reduction/oxidation reaction. Most natural minerals showed lower combustion capacity than pure CuO/Fe{sub 2}O{sub 3} due to low-concentrations of active oxide species in minerals. In coal CLC, chryscolla (Cu-based), magnetite, and limonite (Fe-based) demonstrated better reaction performances than other materials. The addition of steam improved the coal CLC performance when using natural ores because of the steam gasification of coal and the subsequent reaction of gaseous fuels with active oxide species in the natural ores. In methane CLC, chryscolla, hematite, and limonite demonstrated excellent reactivity and stability in 50-cycle thermogravimetric analysis tests. Fe{sub 2}O{sub 3}-based ores possess greater oxygen utilization but require an activation period before achieving full performance in methane CLC. Particle agglomeration issues associated with the application of natural ores in CLC processes were also studied by scanning electron microscopy (SEM).

  14. Process/Equipment Co-Simulation on Syngas Chemical Looping Process

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Liang; Zhou, Qiang; Fan, Liang-Shih

    2012-09-30

    The chemical looping strategy for fossil energy applications promises to achieve an efficient energy conversion system for electricity, liquid fuels, hydrogen and/or chemicals generation, while economically separate CO{sub 2} by looping reaction design in the process. Chemical looping particle performance, looping reactor engineering, and process design and applications are the key drivers to the success of chemical looping process development. In order to better understand and further scale up the chemical looping process, issues such as cost, time, measurement, safety, and other uncertainties need to be examined. To address these uncertainties, advanced reaction/reactor modeling and process simulation are highly desired and the modeling efforts can accelerate the chemical looping technology development, reduce the pilot-scale facility design time and operating campaigns, as well as reduce the cost and technical risks. The purpose of this work is thus to conduct multiscale modeling and simulations on the key aspects of chemical looping technology, including particle reaction kinetics, reactor design and operation, and process synthesis and optimization.

  15. Chemical decontamination of Santa Maria de Garona NPP recirculation loops

    International Nuclear Information System (INIS)

    Coello, R.

    2002-01-01

    Santa Maria de Garona is a boiling water reactor (BWR-3) with a Primary Containment type Mark 1. Its electrical power is 466 Mw and began its commercial operation in 1971. The plant currently operates in 24 month cycles. The reactor water recirculation system (RWRS) is composed of two independent loops. Each of them has a one stage vertical centrifugal recirculation pump, with a nominal flow of 2020 l/s, and ten jet pumps. It is worthy of mention that in 1986 it was started to inject hydrogen into the feedwater (concentration = 0,3 mg/l) in order to implement the chemical condition known as hydrogen water chemistry (HWC) in the primary circuit. The objective was to create an electrochemical potential below -230 mV in the RWRS which is assumed to be low enough to mitigate the intergranular stress corrosion cracking phenomena (IGSCC) in the sensitized austenitic stainless steels. Later, in 1994, the hydrogen concentration in the feedwater was increased to 0,9 mg/l in order to obtain the protection's ECP in the bottom of the reactor vessel. This feedwater hydrogen concentration has been maintained since then. The nature of the oxides that are formed in the RWRS is strongly affected by the electrochemical conditions (ECP) which have been maintained in this system. It is frequent to find oxides like Fe 2 O 3 (hematite), Fe 3 O 4 (magnetite), NiFe 2 O 4 (trevorite), Cr 2 FeO 4 (chromite), Fe 3-x-y Cr x Ni y O 4 (spinels), etc. However, it is normal to find a combination of all of them in various proportions, depending on the ECP established. Radioactive isotopes of the transition metals ( 60 Co, 54 Mn, 51 Cr, 59 Fe, etc.) also participate in these oxides and contribute greatly to increase the dose rate in the circuit. The chemical decontamination processes are designed for the effective dissolution of the metallic oxides present and therefore the type of process to be applied will depend largely on the ECP that has been maintained in the circuit to be decontaminated. For

  16. Thermodynamic analysis of a dual power-hydrogen production system based on chemical-looping combustion

    OpenAIRE

    Urdiales, Álvaro; Jiménez Alvaro, Ángel; Sánchez Orgaz, Susana; González Fernández, M. Celina

    2016-01-01

    Chemical-looping hydrogen generation (CLHG) is a chemical-looping combustion variant that allows simultaneous production of power and hydrogen. A thermodynamic analysis from the exergy method point of view of an integrated syngas-fueled CLHG cycle is carried out with the aim of contributing to the conceptual understanding and development of CLHG systems. The cycle working point is optimized in a range of conditions. The proposed system shows a very interesting potential for power, hydrogen an...

  17. Experimentelle Untersuchung des Chemical Looping Verfahrens an einer 1 MW Versuchsanlage

    OpenAIRE

    Orth, Matthias

    2014-01-01

    Im Zeichen des Klimawandels haben sich führende Industrienationen geeinigt, ihre jeweiligen CO2-Emissionen signifikant zu senken. Diese Reduktionsziele können nur erreicht werden, wenn die Emissionen bei der Energieerzeugung deutlich gesenkt werden. In der vorliegenden Arbeit wird das sogenannte Chemical Looping Verfahren untersucht, bei dem Energie aus fossilen Energieträgern gewonnen und das dabei entstehende CO2 abgeschieden wird. Die aktuelle Forschung im Bereich Chemical Looping konzentr...

  18. Development of Computational Approaches for Simulation and Advanced Controls for Hybrid Combustion-Gasification Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Abhinaya; Lou, Xinsheng; Neuschaefer, Carl; Chaudry, Majid; Quinn, Joseph

    2012-07-31

    This document provides the results of the project through September 2009. The Phase I project has recently been extended from September 2009 to March 2011. The project extension will begin work on Chemical Looping (CL) Prototype modeling and advanced control design exploration in preparation for a scale-up phase. The results to date include: successful development of dual loop chemical looping process models and dynamic simulation software tools, development and test of several advanced control concepts and applications for Chemical Looping transport control and investigation of several sensor concepts and establishment of two feasible sensor candidates recommended for further prototype development and controls integration. There are three sections in this summary and conclusions. Section 1 presents the project scope and objectives. Section 2 highlights the detailed accomplishments by project task area. Section 3 provides conclusions to date and recommendations for future work.

  19. Reactor choices for chemical looping combustion (CLC) dependencies on materials characteristics

    NARCIS (Netherlands)

    Kimball, E.; Lambert, A.; Fossdal, A.; Leenman, R.N.; Comte, E.; Bos, W.A.P. van den; Blom, R.

    2013-01-01

    The physio-chemical stability of the oxygen carrier material during chemical looping combustion (CLC) operation is crucial. In the present paper we discuss the challenges connected to operating a metal oxide base material in a cyclic manner between oxidizing and reducing atmospheres. Especially,

  20. Control of the loop IRENE in the experimental reactor OSIRIS: calculation of the departure from nucleate boiling ratio in real time

    International Nuclear Information System (INIS)

    Lucot, Michel; Obin, Norbert.

    1980-10-01

    The loop IRENE is an experimental device to study the behaviour of pressurized light-water fuel pins under neutron flux in the Saclay Nuclear Research Centre reactor OSIRIS. It can take 8 fuel pins and allows irradiations to be carried out under thermodynamic, hydraulic and chemical conditions corresponding to those of a PWR power reactor. A brief outline of the loop specifications is followed by an account of the difficulties raised by operating with saturation temperature at the test channel outlet and it is shown how the microprocessor loop pilots are used to solve these problems [fr

  1. Experimental Observation of Disorder-Driven Hysteresis-Loop Criticality

    International Nuclear Information System (INIS)

    Berger, A.; Inomata, A.; Jiang, J. S.; Pearson, J. E.; Bader, S. D.

    2000-01-01

    We have studied the effect of magnetic disorder on the magnetization reversal process in thin Co/CoO films. The antiferromagnetic CoO layer allows a reversible tuning of the magnetic disorder by simple temperature variation. For temperatures above a critical temperature T c , we observe a discontinuous magnetization reversal, whereas smooth magnetization loops occur for T c . Our measurements establish the existence of a disorder-driven critical point in the nonequilibrium phase diagram. In addition, we observe scaling behavior in the vicinity of the critical point and determine the critical exponents β=0.022±0.006 and βδ=0.30±0.03 for this two-dimensional system

  2. Chemical looping of metal nitride catalysts: low-pressure ammonia synthesis for energy storage.

    Science.gov (United States)

    Michalsky, R; Avram, A M; Peterson, B A; Pfromm, P H; Peterson, A A

    2015-07-01

    The activity of many heterogeneous catalysts is limited by strong correlations between activation energies and adsorption energies of reaction intermediates. Although the reaction is thermodynamically favourable at ambient temperature and pressure, the catalytic synthesis of ammonia (NH 3 ), a fertilizer and chemical fuel, from N 2 and H 2 requires some of the most extreme conditions of the chemical industry. We demonstrate how ammonia can be produced at ambient pressure from air, water, and concentrated sunlight as renewable source of process heat via nitrogen reduction with a looped metal nitride, followed by separate hydrogenation of the lattice nitrogen into ammonia. Separating ammonia synthesis into two reaction steps introduces an additional degree of freedom when designing catalysts with desirable activation and adsorption energies. We discuss the hydrogenation of alkali and alkaline earth metal nitrides and the reduction of transition metal nitrides to outline a promoting role of lattice hydrogen in ammonia evolution. This is rationalized via electronic structure calculations with the activity of nitrogen vacancies controlling the redox-intercalation of hydrogen and the formation and hydrogenation of adsorbed nitrogen species. The predicted trends are confirmed experimentally with evolution of 56.3, 80.7, and 128 μmol NH 3 per mol metal per min at 1 bar and above 550 °C via reduction of Mn 6 N 2.58 to Mn 4 N and hydrogenation of Ca 3 N 2 and Sr 2 N to Ca 2 NH and SrH 2 , respectively.

  3. Regenerable mixed copper-iron-inert support oxygen carriers for solid fuel chemical looping combustion process

    Energy Technology Data Exchange (ETDEWEB)

    Siriwardane, Ranjani V.; Tian, Hanjing

    2016-12-20

    The disclosure provides an oxygen carrier for a chemical looping cycle, such as the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The oxygen carrier is comprised of at least 24 weight % (wt %) CuO, at least 10 wt % Fe2O3, and an inert support, and is typically a calcine. The oxygen carrier exhibits a CuO crystalline structure and an absence of iron oxide crystalline structures under XRD crystallography, and provides an improved and sustained combustion reactivity in the temperature range of 600.degree. C.-1000.degree. C. particularly for solid fuels such as carbon and coal.

  4. A novel double loop control model design for chemical unstable processes.

    Science.gov (United States)

    Cong, Er-Ding; Hu, Ming-Hui; Tu, Shan-Tung; Xuan, Fu-Zhen; Shao, Hui-He

    2014-03-01

    In this manuscript, based on Smith predictor control scheme for unstable process in industry, an improved double loop control model is proposed for chemical unstable processes. Inner loop is to stabilize integrating the unstable process and transform the original process to first-order plus pure dead-time dynamic stable process. Outer loop is to enhance the performance of set point response. Disturbance controller is designed to enhance the performance of disturbance response. The improved control system is simple with exact physical meaning. The characteristic equation is easy to realize stabilization. Three controllers are separately design in the improved scheme. It is easy to design each controller and good control performance for the respective closed-loop transfer function separately. The robust stability of the proposed control scheme is analyzed. Finally, case studies illustrate that the improved method can give better system performance than existing design methods. © 2013 ISA Published by ISA All rights reserved.

  5. Experimental analysis of a capillary pumped loop for terrestrial applications with several evaporators in parallel

    International Nuclear Information System (INIS)

    Blet, Nicolas; Bertin, Yves; Ayel, Vincent; Romestant, Cyril; Platel, Vincent

    2016-01-01

    Highlights: • This paper introduces experimental studies of a CPLTA with 3 evaporators in parallel. • Operating principles of mono-evaporator CPLTA are reminded. • A reference test with the new bench with only one evaporator is introduced. • Global behavior of the multi-evaporators loop is presented and discussed. • Some additional thermohydraulic couplings are revealed. - Abstract: In the context of high-dissipation electronics cooling for ground transportation, a new design of two-phase loop has been improved in recent years: the capillary pumped loop for terrestrial application (CPLTA). This hybrid system, between the two standard capillary pumped loop (CPL) and loop heat pipe (LHP), has been widely investigated with a single evaporator, and so a single dissipative area, to know its mean operating principles and thermohydraulic couplings between the components. To aim to extend its scope of applications, a new experimental CPLTA with three evaporators in parallel is studied in this paper with methanol as working fluid. Even if the dynamics of the loop in multi-evaporators mode appears on the whole similar to that with a single operating evaporator, additional couplings are highlighted between the several evaporators. A decoupling between vapor generation flow rate and pressure drop in each evaporator is especially revealed. The impact of this phenomenon on the conductance at evaporator is analyzed.

  6. Experimental study of a water thermo-capillary loop; Etude experimentale d`une boucle thermocapillaire a eau

    Energy Technology Data Exchange (ETDEWEB)

    Lefriec, C.; Alexandre, A. [Ecole Nationale Superieure de Mecanique et d`Aerotechnique (ENSMA), 86 - Poitiers (France)

    1996-12-31

    This paper presents a bench scale experiment of a water thermo-capillary loop which allows to improve the understanding of its functioning mechanisms thanks to the internal visualisation of each component using transparent walls. The advantages of water are its non-toxicity, its high chemical compatibility with several materials and its low functioning pressure. The experimental device is presented and the functioning regimes of each component is analyzed: condenser (flow visualization, influence of tilt), evaporator (quality of heat exchange between teeth and porous medium, bubbles, heat exchange coefficient). (J.S.)

  7. An Integrated Photoelectrochemical-Chemical Loop for Solar-Driven Overall Splitting of Hydrogen Sulfide

    DEFF Research Database (Denmark)

    Zong, Xu; Han, Jingfeng; Seger, Brian

    2014-01-01

    Abundant and toxic hydrogen sulfide (H2S) from industry and nature has been traditionally considered a liability. However, it represents a potential resource if valuable H-2 and elemental sulfur can be simultaneously extracted through a H2S splitting reaction. Herein a photochemical-chemical loop...

  8. A novel solar thermal cycle with chemical looping combustion. Paper no. IGEC-1-020

    International Nuclear Information System (INIS)

    Hong, H.; Jin, H.

    2005-01-01

    In this paper, we have proposed a thermal cycle with the integration of chemical-looping combustion and solar thermal energy with the temperature of about 500-600 o C. Chemical-looping combustion may be carried out in two successive reactions between a reduction of hydrocarbon fuel with metal oxides and a reduced metal with oxygen in air. This loop of chemical reaction is substituted for conventional combustion of fuel. Methane as a fuel and nickel oxides as oxygen carrier were employed in this cycle. Collected high-temperature solar thermal energy is provided for the endothermic reduction reaction. The feature of the proposed cycle is investigated through Energy-Utilization Diagram methodology. As a result, at the turbine inlet temperature of 1200 o C, the exergy efficiency of the proposed cycle would expected to be about 4 percentage points higher than that of conventional gas turbine combined cycle. Compared to the previous study of chemical-looping combustion energy system, the proposed cycle with the integration of green energy and traditional hydrocarbon fuels will offer the possibility of both greenhouse gas mitigation with green energy and a new approach of efficient use of solar energy. (author)

  9. A novel reactor configuration for packed bed chemical-looping combustion of syngas

    NARCIS (Netherlands)

    Hamers, H.P.; Gallucci, F.; Cobden, P.D.; Kimball, E.; Sint Annaland, M. van

    2013-01-01

    This study reports on the application of chemical looping combustion (CLC) in pressurized packed bed reactors using syngas as a fuel. High pressure operation of CLC in packed bed has a different set of challenges in terms of material properties, cycle and reactor design compared to fluidized bed

  10. Simulation of an Integrated Gasification Combined Cycle with Chemical-Looping Combustion and CO2 sequestration

    OpenAIRE

    Jiménez Alvaro, Ángel; López Paniagua, Ignacio; González Fernández, M. Celina; Rodríguez Martín, Javier; Nieto Carlier, Rafael

    2014-01-01

    Chemical-looping combustion allows an integration of CO2 capture in a thermal power plant without energy penalty; secondly, a less exergy destruction in the combustion chemical transformation is achieved, leading to a greater overall thermal efficiency. This paper focus on the study of the energetic performance of this concept of combustion in an integrated gasification combined cycle power plant when synthesis gas is used as fuel for the gas turbines. After thermodynamic modelling and optimi...

  11. Chemical looping coal gasification with calcium ferrite and barium ferrite via solid–solid reactions

    International Nuclear Information System (INIS)

    Siriwardane, Ranjani; Riley, Jarrett; Tian, Hanjing; Richards, George

    2016-01-01

    Highlights: • BaFe 2 O 4 and CaFe 2 O 4 are excellent for chemical looping coal gasification. • BaFe 2 O 4 and CaFe 2 O 4 have minimal reactivity with synthesis gas. • Steam enhances the gasification process with these oxygen carriers. • Reaction rates of steam gasification of coal with CaFe 2 O 4 was better than with gaseous oxygen. • Coal gasification appears to be via solid–solid interaction with the oxygen carrier. - Abstract: Coal gasification to produce synthesis gas by chemical looping was investigated with two oxygen carriers, barium ferrite (BaFe 2 O 4 ) and calcium ferrite (CaFe 2 O 4 ). Thermo-gravimetric analysis (TGA) and fixed-bed flow reactor data indicated that a solid–solid interaction occurred between oxygen carriers and coal to produce synthesis gas. Both thermodynamic analysis and experimental data indicated that BaFe 2 O 4 and CaFe 2 O 4 have high reactivity with coal but have a low reactivity with synthesis gas, which makes them very attractive for the coal gasification process. Adding steam increased the production of hydrogen (H 2 ) and carbon monoxide (CO), but carbon dioxide (CO 2 ) remained low because these oxygen carriers have minimal reactivity with H 2 and CO. Therefore, the combined steam–oxygen carrier produced the highest quantity of synthesis gas. It appeared that neither the water–gas shift reaction nor the water splitting reaction promoted additional H 2 formation with the oxygen carriers when steam was present. Wyodak coal, which is a sub-bituminous coal, had the best gasification yield with oxygen carrier–steam while Illinois #6 coal had the lowest. The rate of gasification and selectivity for synthesis gas production was significantly higher when these oxygen carriers were present during steam gasification of coal. The rates and synthesis gas yields during the temperature ramps of coal–steam with oxygen carriers were better than with gaseous oxygen.

  12. Simulation of an integrated gasification combined cycle with chemical-looping combustion and carbon dioxide sequestration

    International Nuclear Information System (INIS)

    Jiménez Álvaro, Ángel; López Paniagua, Ignacio; González Fernández, Celina; Rodríguez Martín, Javier; Nieto Carlier, Rafael

    2015-01-01

    Highlights: • A chemical-looping combustion based integrated gasification combined cycle is simulated. • The energetic performance of the plant is analyzed. • Different hydrogen-content synthesis gases are under study. • Energy savings accounting carbon dioxide sequestration and storage are quantified. • A notable increase on thermal efficiency up to 7% is found. - Abstract: Chemical-looping combustion is an interesting technique that makes it possible to integrate power generation from fuels combustion and sequestration of carbon dioxide without energy penalty. In addition, the combustion chemical reaction occurs with a lower irreversibility compared to a conventional combustion, leading to attain a somewhat higher overall thermal efficiency in gas turbine systems. This paper provides results about the energetic performance of an integrated gasification combined cycle power plant based on chemical-looping combustion of synthesis gas. A real understanding of the behavior of this concept of power plant implies a complete thermodynamic analysis, involving several interrelated aspects as the integration of energy flows between the gasifier and the combined cycle, the restrictions in relation with heat balances and chemical equilibrium in reactors and the performance of the gas turbines and the downstream steam cycle. An accurate thermodynamic modeling is required for the optimization of several design parameters. Simulations to evaluate the energetic efficiency of this chemical-looping-combustion based power plant under diverse working conditions have been carried out, and a comparison with a conventional integrated gasification power plant with precombustion capture of carbon dioxide has been made. Two different synthesis gas compositions have been tried to check its influence on the results. The energy saved in carbon capture and storage is found to be significant and even notable, inducing an improvement of the overall power plant thermal efficiency of

  13. Experimental and theoretical study on density wave instability in low quality natural circulation loop

    International Nuclear Information System (INIS)

    Jia, Hai Jun; Song, Jin Ho

    1997-07-01

    A series of thermal-hydraulic experimental research has been performed at INET of Beijing University in two full scale test loops, HRTL-5 and HRTL-200 simulating the HR-5 and HR-200 district heating reactors. The homogeneous equilibrium flow model and the drift flux model are employed to analyze the flow in the HRTL-200 test loop. The frequency domain linear stability analysis program LINTAB has been developed based on the homogeneous equilibrium results from HRTL-200 test facility have been used to validate the LINTAB code. Analysis results using LINTAB showed a good agreement with the test results. (author). 20 refs., 24 figs

  14. CFD and experimental data of closed-loop wind tunnel flow

    Directory of Open Access Journals (Sweden)

    John Kaiser Calautit

    2016-06-01

    Full Text Available The data presented in this article were the basis for the study reported in the research articles entitled ‘A validated design methodology for a closed loop subsonic wind tunnel’ (Calautit et al., 2014 [1], which presented a systematic investigation into the design, simulation and analysis of flow parameters in a wind tunnel using Computational Fluid Dynamics (CFD. The authors evaluated the accuracy of replicating the flow characteristics for which the wind tunnel was designed using numerical simulation. Here, we detail the numerical and experimental set-up for the analysis of the closed-loop subsonic wind tunnel with an empty test section.

  15. Chemical-Based Formulation Design: Virtual Experimentation

    DEFF Research Database (Denmark)

    Conte, Elisa; Gani, Rafiqul

    This paper presents a software, the virtual Product-Process Design laboratory (virtual PPD-lab) and the virtual experimental scenarios for design/verification of consumer oriented liquid formulated products where the software can be used. For example, the software can be employed for the design......, the additives and/or their mixtures (formulations). Therefore, the experimental resources can focus on a few candidate product formulations to find the best product. The virtual PPD-lab allows various options for experimentations related to design and/or verification of the product. For example, the selection...... design, model adaptation). All of the above helps to perform virtual experiments by blending chemicals together and observing their predicted behaviour. The paper will highlight the application of the virtual PPD-lab in the design and/or verification of different consumer products (paint formulation...

  16. Study of highly efficient power generation system based on chemical-looping combustion; Chemical loop nenshoho ni yoru kokoritsu hatsuden system no kaihatsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, S.; Suzuki, T.; Yamamoto, M. [Tokyo Institute of Technology, Tokyo (Japan). Research Laboratory of Resources Utilization

    1997-02-01

    This paper describes the research and development of power generation system by means of chemical-looping combustion. For this system, fuel flows in a reduction reactor and air flows in an oxidation reactor. These two flows are separated. As a result, recovery of CO2 without energy consumption, drastic improvement of power generation efficiency, and suppression of NOx emission are expected. To realize the above, two promising candidates, NiCoO2/YSZ and NiO2/NiAl2O4, have been found as recycle solid particles between the both reactors. These have excellent oxidation/reduction cycle characteristics. By these particles as well as the existing particle, NiO/YSZ, practical application of the chemical-looping combustion is realized. Besides LNG, coal and hydrogen were considered as fuels. When using coal or hydrogen, it was found that temperature of the reduction reactor should be increased the same as that of the oxidation reactor. This is a different point from a case using LNG as a fuel. 5 refs., 2 figs.

  17. Results of theoretical and experimental studies of hydrodynamics of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors

    Science.gov (United States)

    Ryabov, G. A.; Folomeev, O. M.; Sankin, D. A.; Melnikov, D. A.

    2015-02-01

    Problems of the calculation of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors (polygeneration systems for the production of electricity, heat, and useful products and chemical cycles of combustion and gasification of solid fuels)are considered. A method has been developed for the calculation of circulation loop of fuel particles with respect to boilers with circulating fluidized bed (CFB) and systems with interconnected reactors with fluidized bed (FB) and CFB. New dependences for the connection between the fluidizing agent flow (air, gas, and steam) and performance of reactors and for the whole system (solids flow rate, furnace and cyclone pressure drops, and bed level in the riser) are important elements of this method. Experimental studies of hydrodynamics of circulation loops on the aerodynamic unit have been conducted. Experimental values of pressure drop of the horizontal part of the L-valve, which satisfy the calculated dependence, have been obtained.

  18. Calcium and chemical looping technology for power generation and carbon dioxide (CO2) capture solid oxygen- and CO2-carriers

    CERN Document Server

    Fennell, Paul

    2015-01-01

    Calcium and Chemical Looping Technology for Power Generation and Carbon Dioxide (CO2) Capture reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to chemical looping and combustion. Chapters review the market development, economics, and deployment of these systems, also providing detailed information on the variety of materials and processes that will help to shape the future of CO2 capture ready power plants. Reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to calcium and chemical loopingProvi

  19. SIMULATION AND EXPERIMENTAL RESULTS FOR THE CLOSED LOOP CONTROLLED DC TO DC FORWARD CONVERTER

    Directory of Open Access Journals (Sweden)

    A. Palamalai VIJAYAKUMAR

    2017-06-01

    Full Text Available A Closed loop controlled DC to DC forward converter is a requisite for the server SMPS system. High efficiency, Isolation, Steady state voltage, Transient response, High switching frequency, reduced noises and range of steady state are all necessary requirements for the forward converter. In this paper, a 40 V forward converter for charging the battery of server SMPS is proposed. The proposed converter consists of a NPC-ARS circuit for soft switching on the primary side and an isolation transformer and a rectifier structure on the secondary side. With this modified NPC-ARS circuit topology, soft switching occurs during conversion and reduces the switching loss in this system. This paper proposed the simulation of closed loop controlled circuit, for the forward converter with RCD snubber, double forward converter and the Modified forward converter are analyzed and discussed in this paper. From comparison of performance in the closed loop model, a suitable converter is proposed for the sever SMPS system. The proposed circuit achieves steady state voltage, when the disturbance occurs. A 40 V proposed circuit is designed as experimental model to verify and compare the simulation and experimental results. This paper proposed the simulation and experimental results of the forward converter.

  20. Comparison of numerical results with experimental data for single-phase natural convection in an experimental sodium loop

    International Nuclear Information System (INIS)

    Ribando, R.J.

    1979-01-01

    A comparison is made between computed results and experimental data for a single-phase natural convection test in an experimental sodium loop. The test was conducted in the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility, an engineering-scale high temperature sodium loop at the Oak Ridge National Laboratory (ORNL) used for thermal-hydraulic testing of simulated Liquid Metal Fast Breeder Reactor (LMFBR) subassemblies at normal and off-normal operating conditions. Heat generation in the 19 pin assembly during the test was typical of decay heat levels. The test chosen for analysis in this paper was one of seven natural convection runs conducted in the facility using a variety of initial conditions and testing parameters. Specifically, in this test the bypass line was open to simulate a parallel heated assembly and the test was begun with a pump coastdown from a small initial forced flow. The computer program used to analyze the test, LONAC (LOw flow and NAtural Convection) is an ORNL-developed, fast-running, one-dimensional, single-phase, finite-difference model used for simulating forced and free convection transients in the THORS loop

  1. Comparison of numerical results with experimental data for single-phase natural convection in an experimental sodium loop. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Ribando, R.J.

    1979-01-01

    A comparison is made between computed results and experimental data for a single-phase natural convection test in an experimental sodium loop. The test was conducted in the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility, an engineering-scale high temperature sodium loop at the Oak Ridge National Laboratory (ORNL) used for thermal-hydraulic testing of simulated Liquid Metal Fast Breeder Reactor (LMFBR) subassemblies at normal and off-normal operating conditions. Heat generation in the 19 pin assembly during the test was typical of decay heat levels. The test chosen for analysis in this paper was one of seven natural convection runs conducted in the facility using a variety of initial conditions and testing parameters. Specifically, in this test the bypass line was open to simulate a parallel heated assembly and the test was begun with a pump coastdown from a small initial forced flow. The computer program used to analyze the test, LONAC (LOw flow and NAtural Convection) is an ORNL-developed, fast-running, one-dimensional, single-phase, finite-difference model used for simulating forced and free convection transients in the THORS loop.

  2. Experimental investigation of the thermal hydraulics of supercritical water under natural circulation in a closed loop

    International Nuclear Information System (INIS)

    Kiss, Attila; Balaskó, Márton; Horváth, László; Kis, Zoltán; Aszódi, Attila

    2017-01-01

    Graphical abstract: The structure of the ANCARA loop (Balaskó et al., 2013) with the meters and short name of each element (for the meaning of the abbreviations please consult with the List of abbreviations). - Highlights: • A small size, closed experimental loop has been designed and built. • The diameter of loop equals to average hydraulic diameter of sub-channels of HPLWR. • The TH of natural circulation in supercritical water was investigated by the loop. • Interesting trends in steady state characteristic and pressure drop have been shown. • Driving force behind decrease of the neutron attenuation is decreasing water density. - Abstract: The thermal hydraulics of supercritical water under forced-, mixed convection and natural circulation conditions is not fully understood. In order to study the thermal hydraulic behaviour of this fluid under natural circulation conditions a small size, closed experimental loop has been designed and built. The thermal hydraulic phenomenon occurring in the loop can be measured by thermocouples mounted onto the outer surface of the heated tube wall, absolute and differential pressure transducers and a flow meter; moreover, simultaneously can be visualized by neutron radiography techniques. This paper describes the loop itself, the process of the experiment with the measurement techniques, the data acquisition system applied and the results got during the first measurement series. Based on the results of the first measurement series, it was found that the measured part of the steady state characteristic is independent from the system pressure. A slight dependence of steady state characteristic on the inlet temperature can be identified: the higher the inlet temperature the higher the mass flow rate. The total pressure drop and its components seem to be independent from the system pressure but strongly dependent on the inlet temperature due to the influence of bulk-fluid temperature on the relevant thermophysical

  3. Morphology evolution and nanostructure of chemical looping transition metal oxide materials upon redox processes

    International Nuclear Information System (INIS)

    Qin, Lang; Cheng, Zhuo; Guo, Mengqing; Fan, Jonathan A.; Fan, Liang-Shih

    2017-01-01

    Transition metal are heavily used in chemical looping technologies because of their high oxygen carrying capacity and high thermal reactivity. These oxygen activities result in the oxide formation and oxygen vacancy formation that affect the nanoscale crystal phase and morphology within these materials and their subsequent bulk chemical behavior. In this study, two selected earlier transition metals manganese and cobalt as well as two selected later transition metals copper and nickel that are important to chemical looping reactions are investigated when they undergo cyclic redox reactions. We found Co microparticles exhibited increased CoO impurity presence when oxidized to Co 3 O 4 upon cyclic oxidation; CuO redox cycles prefer to be limited to a reduced form of Cu 2 O and an oxidized form of CuO; Mn microparticles were oxidized to a mixed phases of MnO and Mn 3 O 4 , which causes delamination during oxidation. For Ni microparticles, a dense surface were observed during the redox reaction. The atomistic thermodynamics methods and density functional theory (DFT) calculations are carried out to elucidate the effect of oxygen dissociation and migration on the morphological evolution of nanostructures during the redox processes. Our results indicate that the earlier transition metals (Mn and Co) tend to have stronger interaction with O 2 than the later transition metals (Ni and Cu). Also, our modified Brønsted−Evans−Polanyi (BEP) relationship for reaction energies and total reaction barriers reveals that reactions of earlier transition metals are more exergonic and have lower oxygen dissociation barriers than those of later transition metals. In addition, it was found that for these transition metal oxides the oxygen vacancy formation energies increase with the depth. The oxide in the higher oxidation state of transition metal has lower vacancy formation energy, which can facilitate forming the defective nanostructures. The fundamental understanding of these

  4. Experimental evaluation of the parameter-based closed-loop transfer function identification for electro-hydraulic servo systems

    Directory of Open Access Journals (Sweden)

    Guang-Da Liu

    2016-12-01

    Full Text Available Closed-loop systems of an electro-hydraulic servo system including position, acceleration, and force closed-loop systems and their closed-loop transfer functions based on parameter model are adaptive identified using a recursive extended least-squares algorithm. The position and force closed-loop tracking controllers are designed by a proportional–integral–derivative controller and are tuned by the position and force step signals. The acceleration closed-loop tracking controller is designed by a three-variable controller and the three states include position, velocity, and acceleration. Experimental results of the estimated position, acceleration, and force closed-loop transfer functions are performed on an actual electro-hydraulic servo system using xPC rapid prototyping technology, which clearly demonstrate the benefit of the adaptive identification method.

  5. Chemical looping reforming of waste cooking oil in packed bed reactor.

    Science.gov (United States)

    Pimenidou, P; Rickett, G; Dupont, V; Twigg, M V

    2010-08-01

    Chemical looping steam reforming for hydrogen production from waste cooking oil was investigated using a packed bed reactor. The steam to carbon ratio of 4 and temperatures between 600 and 700 degrees C yielded the best results of the range of conditions tested. Six cycles at two weighted hourly space velocities (WHSV of 2.64 and 5.28 h(-1)) yielded high (>0.74) and low (syngas composition with H(2) selectivity very close to the optimum. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. Experimental and theoretical studies in Molten Salt Natural Circulation Loop (MSNCL)

    International Nuclear Information System (INIS)

    Srivastava, A.K.; Borgohain, A.; Jana, S.S.; Bagul, R.K.; Singh, R.R.; Maheshwari, N.K.; Belokar, D.G.; Vijayan, P.K.

    2014-12-01

    High Temperature Reactors (HTR) and solar thermal power plants use molten salt as a coolant, as it has low melting point and high boiling point, enabling us to operate the system at low pressure. Molten fluoride salt and molten nitrate salt are proposed as a candidate coolant for High Temperature Reactors (HTR) and solar power plant respectively. BARC is developing a 600 MWth pebble bed high temperature reactor, cooled by natural circulation of fluoride salt and capable of supplying process heat at 1000°C to facilitate hydrogen production by splitting water. Beside this, BARC is also developing a 2MWe solar power tower system using molten nitrate salt. With these requirements, a Molten Salt Natural Circulation Loop (MSNCL) has been designed, fabricated, installed and commissioned in Hall-7, BARC for thermal hydraulic, instrumentation development and material compatibility related studies. Steady state natural circulation experiments with molten nitrate salt (mixture of NaNO 3 and KNO 3 in 60:40 ratio) have been carried out in the loop at different power level. Various transients viz. startup of natural circulation, step power change, loss of heat sink and heater trip has also been studied in the loop. A well known steady state correlation given by Vijayan et. al. has been compared with experimental data. In-house developed code LeBENC has also been validated against all steady state and transient experimental results. The detailed description of MSNCL, steady state and transient experimental results and validation of in-house developed code LeBENC have been described in this report. (author)

  7. Oxidation and Reduction of Iron-Titanium Oxides in Chemical Looping Combustion: A Phase-Chemical Description

    International Nuclear Information System (INIS)

    Den Hoed, P.; Luckos, A.

    2011-01-01

    Ilmenite (FeTiO 3 ) is being explored as an oxygen carrier in chemical looping processes. Its reduction and oxidation are described by the system Fe-Fe 2 O 3 -TiO 2 -Ti 2 O 3 . The phase diagram at 1 000 C, presented here, offers a useful tool for predicting reactions and their products. We see that Fe 2 TiO 5 (pseudo-brookite) and TiO 2 (rutile) form a stable phase assemblage following the oxidation of FeTiO 3 (ilmenite) in air. The subsequent reduction of Fe 2 TiO 5 at oxygen partial pressures of 10 -15.5 atm stabilizes Fe 1.02 Ti 0.98 O 3 , a solid solution of ilmenite. Further reduction will produce metallic iron, which compromises the integrity of the oxygen carrier for chemical looping processes. We speculate that the reduction of Fe-Ti oxides in several practical instances does not reach completion (and equilibrium) under the imposed atmospheres operating in fuel reactors. (authors)

  8. A hybrid solar chemical looping combustion system with a high solar share

    International Nuclear Information System (INIS)

    Jafarian, Mehdi; Arjomandi, Maziar; Nathan, Graham J.

    2014-01-01

    Highlights: • A novel hybrid solar chemical looping combustion system is presented. • This hybrid CLC system integrates a CLC plant with a solar thermal energy plant. • The oxygen carrier particles are used for chemical and sensible thermal energy storage. • A solar cavity reactor is proposed for fuel reactor. • The calculations show a total solar share of around 60% can be achieved. - Abstract: A novel hybrid solar chemical looping combustion (Hy-Sol-CLC) is presented, in which the oxygen carrier particles in a CLC system are employed to provide thermal energy storage for concentrated solar thermal energy. This hybrid aims to take advantage of key features of a chemical looping combustion (CLC) system that are desirable for solar energy systems, notably their inherent chemical and sensible energy storage systems, the relatively low temperature of the “fuel” reactor (to which the concentrated solar thermal energy is added in a hybrid) relative to that of the final temperature of the product gas and the potential to operate the fuel reactor at a different pressure to the heated gas stream. By this approach, it is aimed to achieve high efficiency of the solar energy, infrastructure sharing, economic synergy, base load power generation and a high solar fraction of the total energy. In the proposed Hy-Sol-CLC system, a cavity solar receiver has been chosen for fuel reactor while for the storage of the oxygen carrier particles two reservoirs have been added to a conventional CLC. A heat exchanger is also proposed to provide independent control of the temperatures of the storage reservoirs from those of solar fuel and air reactors. The system is simulated using Aspen Plus software for the average diurnal profile of normal irradiance for Port Augusta, South Australia. The operating temperature of the fuel reactor, solar absorption efficiency, solar share, fraction of the solar thermal energy stored within the solar reactor, the fractions of sensible and

  9. SDG and E - ERDA Geothermal Loop Experimental Facility. Bi-monthly report, May 1975-August 1976

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, H.K.; Bricarello, J.R.; Campbell, J.A.; Lombard, G.L.; Mulliner, D.K.; Swanson, C.R.

    1976-09-01

    A description of the Geothermal Loop Experimental Facility (GLEF) its construction problems, and a discussion of start-up testing are included. A history and description of the operation and maintenance with the brine injection pump for the facility are presented. The GLEF was divided into five separate sections: steam and condensate system, brine system, purge water system, vent gas system, and cooling water system. An insight into the chemistry of each system is provided by analysis of samples taken. Scaling and corrosion effects of brine, steam, gas, and water in these systems are described in detail. (MHR)

  10. Experimental loop for fast neutron fuels under normal, abnormal, transient and emergency conditions

    International Nuclear Information System (INIS)

    Bauge, M.; Colomez, G.; Marfaing, R.J.; Mourain, M.

    1976-01-01

    Within the scope of safety experiments on power reactor fuels, an experimental loop is described which can, by reduction of the flow, flush the sodium joint of vented mixed carbide fuel elements and allow the study of the resulting phenomena. With the help of the annex laboratories at OSIRIS, the control test can be analyzed and followed, with special attention to the study of the migration of fission products inside and outside the fuel. This apparatus can, of course, also be used for testing the fuels under normal and abnormal working conditions [fr

  11. Comparison of Iron and Tungsten Based Oxygen Carriers for Hydrogen Production Using Chemical Looping Reforming

    Science.gov (United States)

    Khan, M. N.; Shamim, T.

    2017-08-01

    Hydrogen production by using a three reactor chemical looping reforming (TRCLR) technology is an innovative and attractive process. Fossil fuels such as methane are the feedstocks used. This process is similar to a conventional steam-methane reforming but occurs in three steps utilizing an oxygen carrier. As the oxygen carrier plays an important role, its selection should be done carefully. In this study, two oxygen carrier materials of base metal iron (Fe) and tungsten (W) are analysed using a thermodynamic model of a three reactor chemical looping reforming plant in Aspen plus. The results indicate that iron oxide has moderate oxygen carrying capacity and is cheaper since it is abundantly available. In terms of hydrogen production efficiency, tungsten oxide gives 4% better efficiency than iron oxide. While in terms of electrical power efficiency, iron oxide gives 4.6% better results than tungsten oxide. Overall, a TRCLR system with iron oxide is 2.6% more efficient and is cost effective than the TRCLR system with tungsten oxide.

  12. Syngas Generation from Methane Using a Chemical-Looping Concept: A Review of Oxygen Carriers

    Directory of Open Access Journals (Sweden)

    Kongzhai Li

    2013-01-01

    Full Text Available Conversion of methane to syngas using a chemical-looping concept is a novel method for syngas generation. This process is based on the transfer of gaseous oxygen source to fuel (e.g., methane by means of a cycling process using solid oxides as oxygen carriers to avoid direct contact between fuel and gaseous oxygen. Syngas is produced through the gas-solid reaction between methane and solid oxides (oxygen carriers, and then the reduced oxygen carriers can be regenerated by a gaseous oxidant, such as air or water. The oxygen carrier is recycled between the two steps, and the syngas with a ratio of H2/CO = 2.0 can be obtained successively. Air is used instead of pure oxygen allowing considerable cost savings, and the separation of fuel from the gaseous oxidant avoids the risk of explosion and the dilution of product gas with nitrogen. The design and elaboration of suitable oxygen carriers is a key issue to optimize this method. As one of the most interesting oxygen storage materials, ceria-based and perovskite oxides were paid much attention for this process. This paper briefly introduced the recent research progresses on the oxygen carriers used in the chemical-looping selective oxidation of methane (CLSOM to syngas.

  13. Experimental and computational analysis of pressure response in a multiphase flow loop

    Science.gov (United States)

    Morshed, Munzarin; Amin, Al; Rahman, Mohammad Azizur; Imtiaz, Syed

    2016-07-01

    The characteristics of multiphase fluid flow in pipes are useful to understand fluid mechanics encountered in the oil and gas industries. In the present day oil and gas exploration is successively inducing subsea operation in the deep sea and arctic condition. During the transport of petroleum products, understanding the fluid dynamics inside the pipe network is important for flow assurance. In this case the information regarding static and dynamic pressure response, pressure loss, optimum flow rate, pipe diameter etc. are the important parameter for flow assurance. The principal aim of this research is to represents computational analysis and experimental analysis of multi-phase (L/G) in a pipe network. This computational study considers a two-phase fluid flow through a horizontal flow loop with at different Reynolds number in order to determine the pressure distribution, frictional pressure loss profiles by volume of fluid (VOF) method. However, numerical simulations are validated with the experimental data. The experiment is conducted in 76.20 mm ID transparent circular pipe using water and air in the flow loop. Static pressure transducers are used to measure local pressure response in multiphase pipeline.

  14. FLICA III. A digital computer program for thermal-hydraulic analysis of reactors and experimental loops

    International Nuclear Information System (INIS)

    Plas, Roger.

    1975-05-01

    This computer program describes the flow and heat transfer in steady and transient state in two-phase flows. It is the present stage of the evolution about FLICA, FLICA II and FLICA II B codes which have been used and developed at CEA for the thermal-hydraulic analysis of reactors and experimental loops with heating rod bundles. In the mathematical model all the significant terms of the fundamental hydrodynamic equations are taken into account with the approximations of turbulent viscosity and conductivity. The two-phase flow is calculated by the homogeneous model with slip. In the flow direction an implicit resolution scheme is available, which make possible to study partial or total flow blockage, with upstream and downstream effects. A special model represents the helical wire effects in out-of pile experimental rod bundles [fr

  15. Experimental investigation on natural circulation and air-injection enhanced circulation in a simple loop

    International Nuclear Information System (INIS)

    Walter Ambrosini; Nicola Forgione; Francesco Oriolo; Filippo Pellacani; Mariano Tarantino; Claudio Struckmann

    2005-01-01

    Full text of publication follows: Natural circulation represents an interesting phenomenon because of both the complex aspects characterising it and for the widespread application in industry. On the other hand, injection of a gas into a rising branch of a loop represents a means to establish or to enhance a circulation flow, as it occurs in the so-called 'air-lift' loops. Both natural circulation and gas-injection enhanced circulation are presently considered for cooling Accelerator Driven System (ADS) reactors. These are subcritical reactors in which the fission reaction chain is maintained by the injection of neutrons obtained by spallation reactions in a target through a high energy proton beam generated in an external accelerator. The capability of such reactors to be used as incinerators of long lived fission products makes them particularly interesting in the light of the closure of the nuclear fuel cycle. Some of the fluids proposed as coolants for these reactors are liquid metals, with main interest for lead and lead-bismuth eutectic (LBE). Experimental activities are being performed in support to the design of the reactor prototype by different organisations. The university of Pisa, in addition to provide cooperation in these large scale activities performed with LBE has set up a specific experimental program aimed at studying the fundamental mechanisms involved in natural circulation and gas-injection enhanced circulation. The adopted experimental facility consists in a simple loop, having a rectangular lay-out (roughly, 4 m tall and 1 m wide), equipped with a 5 kW, 1 m tall heater, a 2 m long pipe-in-pipe heat exchanger, an air injection device and a separator. The fluid adopted in the tests performed up to now is water, though studies for evaluating the feasibility of the adoption of different fluids have been undertaken. Experimental data reported in previous publications concerning this research were related to a relatively high range of gas

  16. Fabrication and processing of next-generation oxygen carrier materials for chemical looping combustion

    Energy Technology Data Exchange (ETDEWEB)

    Nadarajah, Arunan [Univ. of Toledo, OH (United States)

    2017-04-26

    Among numerous methods of controlling the global warming effect, Chemical Looping Combustion is known to be the most viable option currently. A key factor to a successful chemical looping process is the presence of highly effective oxygen carriers that enable fuel combustion by going through oxidation and reduction in the presence of air and fuel respectively. In this study, CaMnO3-δ was used as the base material and doped on the A-site (Sr or La) and B-site (Fe, Ti, Zn and Al) by 10 mol % of dopants. Solid state reaction followed by mechanical extrusion (optimized paste formula) was used as the preparation method A series of novel doped perovskite-type oxygen carrier particles (CaxLa (Or Sa)1-x Mn1-yByO3-δ (B-site = Fe, Ti, Al, or Zr)) were synthesized by the proposed extrusion formula. The produced samples were characterized with XRD, SEM, BET and TGA techniques. According to the results obtained from TGA analysis, the oxygen capacity of the samples ranged between 1.2 for CLMZ and 1.75 for CSMF. Reactivity and oxygen uncoupling behaviors of the prepared samples were also evaluated using a fluidized bed chemical looping reactor using methane as the fuel at four different temperatures (800, 850, 900, 950 °C). All of the oxygen carriers showed oxygen uncoupling behavior and they were able to capture and release oxygen. Mass-based conversion of the perovskites was calculated and temperature increase proved to increase the mass-based conversion rate in all of the samples under study. Gas yield was calculated at 950 °C as well, and results showed that CLMZ, CM and CSMF showed 100% gas yields and CLMF and CSMZ showed approximately 85% yield in fluidized bed reactor, which is a high and acceptable quantity. Based on extended reactor tests the modified calcium manganese perovskite structures (CSMF) can be a good candidate for future pilot tests.

  17. Recovery Act: Novel Oxygen Carriers for Coal-fueled Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wei-Ping; Cao, Yan

    2012-11-30

    Chemical Looping Combustion (CLC) could totally negate the necessity of pure oxygen by using oxygen carriers for purification of CO{sub 2} stream during combustion. It splits the single fuel combustion reaction into two linked reactions using oxygen carriers. The two linked reactions are the oxidation of oxygen carriers in the air reactor using air, and the reduction of oxygen carriers in the fuel reactor using fuels (i.e. coal). Generally metal/metal oxides are used as oxygen carriers and operated in a cyclic mode. Chemical looping combustion significantly improves the energy conversion efficiency, in terms of the electricity generation, because it improves the reversibility of the fuel combustion process through two linked parallel processes, compared to the conventional combustion process, which is operated far away from its thermo-equilibrium. Under the current carbon-constraint environment, it has been a promising carbon capture technology in terms of fuel combustion for power generation. Its disadvantage is that it is less mature in terms of technological commercialization. In this DOE-funded project, accomplishment is made by developing a series of advanced copper-based oxygen carriers, with properties of the higher oxygen-transfer capability, a favorable thermodynamics to generate high purity of CO{sub 2}, the higher reactivity, the attrition-resistance, the thermal stability in red-ox cycles and the achievement of the auto-thermal heat balance. This will be achieved into three phases in three consecutive years. The selected oxygen carriers with final-determined formula were tested in a scaled-up 10kW coal-fueled chemical looping combustion facility. This scaled-up evaluation tests (2-day, 8-hour per day) indicated that, there was no tendency of agglomeration of copper-based oxygen carriers. Only trace-amount of coke or carbon deposits on the copper-based oxygen carriers in the fuel reactor. There was also no evidence to show the sulphidization of oxygen

  18. Experimental evaluation of reactivity constraints for the closed-loop control of reactor power

    International Nuclear Information System (INIS)

    Bernard, J.A.; Lanning, D.D.; Ray, A.

    1984-01-01

    General principles for the closed-loop, digital control of reactor power have been identified, quantitatively enumerated, and experimentally demonstrated on the 5 MWt Research Reactor, MITR-II. The basic concept is to restrict the net reactivity so that it is always possible to make the reactor period infinite at the desired termination point of a transient by reversing the direction of motion of whatever control mechanism is associated with the controller. This capability is formally referred to as ''feasibility of control''. A series of ten experiments have been conducted over a period of eighteen months to demonstrate the efficacy of this property for the automatic control of reactor power. It has been shown that a controller which possesses this property is capable of both raising and lowering power in a safe, efficient manner while using a control rod of varying differential worth, that the reactivity constraints are a sufficient condition for the automatic control of reactor power, and that the use of a controller based on reactivity constraints can prevent overshoots either due to attempts to control a transient with a control rod of insufficient differential worth or due to failure to properly estimate when to commence rod insertion. Details of several of the more significant tests are presented together with a discussion of the rationale for the development of closed-loop control in large commercial power systems. Specific consideration is given to the motivation for designing a controller based on feasibility of control and the associated licensing issues

  19. A comparative study of geopolymers synthesized from OXY-combustion and chemical looping combustion bottom ashes

    CSIR Research Space (South Africa)

    Nkuna, CN

    2017-04-01

    Full Text Available under fluidised bed conditions, is 51 Chemical looping combustion (CLC). CLC is a process where metal oxides are used to 52 transport the oxygen between the two reactors, fuel reactor and air reactor [3-5]. In the fuel 53 reactor the metal oxide... reacts with the fuel to produce CO2 and H2O as fuel gases [ (CnHn)m + 54 (2n+m)MexOy →nCO2 + mH2O + (2n+m)MexOy-1].The reduced metal oxide is transported 55 into the air reactor in order to be oxidized by air [O2 + 2MexOy-1 →2MexOy], then oxidized 56...

  20. Thermodynamic Feasibility of Hydrogen-Rich Gas Production Supported by Iron Based Chemical Looping Process

    Directory of Open Access Journals (Sweden)

    Grzegorz Słowiński

    2016-01-01

    Full Text Available The continuously increasing oil prices as well as stronger environmental regulations regarding greenhouse emissions made the greatest economic powers search a new, price competitive, and environment friendly energy carrier, such as hydrogen. The world research activities in these terms focus on the development of integrated hydrogen and power generating technologies, particularly technologies of hydrogen production from various carbonaceous resources, like methane, coal, biomass, or waste, often combined with carbon dioxide capture. In the paper the thermodynamic analysis of the enhancement of hydrogen production in iron based chemical looping process is presented. In this method, iron oxide is first reduced to iron with a reducing agent, such as carbon oxide, hydrogen, or mixture of both gases (synthesis gas, and then, in the inverse reaction with steam, it is regenerated to iron oxide, and pure stream of hydrogen is produced.

  1. Chemical Looping Combustion of Hematite Ore with Methane and Steam in a Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Samuel Bayham

    2017-08-01

    Full Text Available Chemical looping combustion is considered an indirect method of oxidizing a carbonaceous fuel, utilizing a metal oxide oxygen carrier to provide oxygen to the fuel. The advantage is the significantly reduced energy penalty for separating out the CO2 for reuse or sequestration in a carbon-constrained world. One of the major issues with chemical looping combustion is the cost of the oxygen carrier. Hematite ore is a proposed oxygen carrier due to its high strength and resistance to mechanical attrition, but its reactivity is rather poor compared to tailored oxygen carriers. This problem is further exacerbated by methane cracking, the subsequent deposition of carbon and the inability to transfer oxygen at a sufficient rate from the core of the particle to the surface for fuel conversion to CO2. Oxygen needs to be readily available at the surface to prevent methane cracking. The purpose of this work was to demonstrate the use of steam to overcome this issue and improve the conversion of the natural gas to CO2, as well as to provide data for computational fluid dynamics (CFD validation. The steam will gasify the deposited carbon to promote the methane conversion. This work studies the performance of hematite ore with methane and steam mixtures in a 5 cm fluidized bed up to approximately 140 kPa. Results show an increased conversion of methane in the presence of steam (from 20–45% without steam to 60–95% up to a certain point, where performance decreases. Adding steam allows the methane conversion to carbon dioxide to be similar to the overall methane conversion; it also helped to prevent carbon accumulation from occurring on the particle. In general, the addition of steam to the feed gas increased the methane conversion. Furthermore, the addition of steam caused the steam methane reforming reaction to form more hydrogen and carbon monoxide at higher steam and methane concentrations, which was not completely converted at higher concentrations and

  2. Experimental research of transient processes in firmware digital phase-locked loop

    Directory of Open Access Journals (Sweden)

    Bondariev A. P.

    2016-10-01

    Full Text Available This article considers the experimental research of transient processes that occur in digital phase-locked loops (DPLL after closing the feedback loop. Firmware implementation of DPLL device was made for this purpose. The paper shows the block diagram of the DPLL and describes its mathematical model. In particular, the location of poles and zeros of DPLL transfer function was determined by the transfer function of the 2nd order analog PLL and the formulas for digital filter coefficients were deducted. The article also represents the block diagram of hardware part of the firmware DPLL. Its key part is the STM microcontroller which is connected to the PC. For convenience reasons, the unique interface between the microcontroller and the PC was created in order to present waveforms of several signals simultaneously. Moreover, the paper depicts the algorithm of software part of the firmware DPLL in general as well as the detailed algorithm of voltage-controlled oscillator (VCO operation – it works as direct digital synthesizer (DDS. The experimental research of the frequency acquisition process of harmonic oscillation was performed for three different sets of DPLL parameters. For each case the location of DPLL poles and zeros and plots of DPLL key signals (tracking error, current frequency and phase of output signal were shown. Obtained diagrams demonstrate that a change of the DPLL natural frequency and damping factor influences on the transient process duration. Pictures signal waveforms from oscilloscope confirm these results. Furthermore, the results of the firmware DPLL research correspond to investigation results of existing simulation model of this DPLL with sufficient accuracy.

  3. Experimental analysis and FEM simulation of loop heat charged with diamond nanofluid for desktop PC cooling

    Science.gov (United States)

    Gunnasegaran, P.; Abdullah, M. Z.; Yusoff, M. Z.

    2015-09-01

    This paper discusses the impact of diamond nanofluid on heat transfer characteristics in a Loop Heat Pipe (LHP). In this study, diamond nanoparticles in water with particle mass concentration ranged from 0% to 3% is considered as the operational fluid within the LHP. The experiments are carried out by manufacturing the LHP, in which the setup consists of a water tank with pump, a flat evaporator, condenser installed with two pieces of fans, two transportation lines (vapor and liquid lines), copper pipe sections for attachment of the thermocouples and power supply. The uniqueness of the current experimental setup is the vapor line of LHP which is made of transparent plastic tube to visualize the fluid flow patterns. The experimental results are verified by Finite Element (FE) simulation using a three-dimensional (3D) model based on the heat transfer by conduction where the LHP as a whole is modeled by assuming it as a conducting medium without taking into account the events occurring inside the LHP. The LHP performance is evaluated in terms of transient temperature distribution and total thermal resistance (Rt). The experimental and simulation results are found in good agreement.

  4. Thermo-hydrodynamics of closed loop pulsating heat pipe: an experimental study

    International Nuclear Information System (INIS)

    Pachghare, Pramod R.; Mahalle, Ashish

    2014-01-01

    The experimental result on the thermal performance of closed loop pulsating heat pipe (CLPHP) is presented. The CLPHP is made of copper capillary tubes, having inner and outer diameters of 2.0 mm and 3.6 mm respectively. The working fluids employed are water, ethanol, methanol and acetone also binary mixture (1:1 by volume) of water-ethanol, water-methanol and water-acetone. For all experimentations, filling ratio (FR) 50%, two-turns and vertical bottom heat mode position was maintained. The lengths of evaporator, condenser and adiabatic section are selected as 42 mm, 50 mm and 170 mm, respectively. The transparent adiabatic section is partially made of glass tube having length 80 mm, for flow visualization. The CFD analysis by VOF model in Star CCM+ simulation is carried out to validate the experimental results. The result shows that the thermal resistance decreases smoothly up to 40W heat input, thereafter reasonably steady. In comparison with all working fluids, water-acetone binary working fluid has shown the best thermal performance over other working fluids used in CLPHPs.

  5. EXPERIMENTAL VALIDATION OF A DUAL LOOP CONTROL OF TWO PHASES INTERLEAVED BOOST CONVERTER FOR FUEL CELL APPLICATIONS

    Directory of Open Access Journals (Sweden)

    O. Kraa

    2016-05-01

    Full Text Available In this paper, a modelling, an implementation and a control of a dc-dc converter structure called “two phases Interleaved Boost Converter (IBC” will be presented. This topology is widely used in order to reduce the input current ripples and the size of passive component with high efficiency. The control of the IBC converter is designed by dual loop control that contains a voltage loop with a linear PI controller and a fast current loop with a non-linear sliding controller to ensure a good tracking in steady state and fast performance in transient state. The proposed control loop has been validated, first by the simulation results under Matlab-Simulink and after by the experimental results using a small-scale test bench with the dSPACE-1104 card.

  6. Simulation of the Fuel Reactor of a Coal-Fired Chemical Looping Combustor

    Science.gov (United States)

    Mahalatkar, Kartikeya; O'Brien, Thomas; Huckaby, E. David; Kuhlman, John

    2009-06-01

    Responsible carbon management (CM) will be required for the future utilization of coal for power generation. CO2 separation is the more costly component of CM, not sequestration. Most methods of capture require a costly process of gas separation to obtain a CO2-rich gas stream. However, recently a process termed Chemical Looping Combustion (CLC) has been proposed, in which an oxygen-carrier is used to provide the oxygen for combustion. This process quite naturally generates a separate exhaust gas stream containing mainly H2O and CO2 but requires two reaction vessels, an Air Reactor (AR) and a Fuel Reactor (FR). The carrier (M for metal, the usual carrier) is oxidized in the AR. This highly exothermic process provides heat for power generation. The oxidized carrier (MO) is separated from this hot, vitiated air stream and transported to the FR where it oxidizes the hydrocarbon fuel, yielding an exhaust gas stream of mainly H2O and CO2. This process is usually slightly endothermic so that the carrier must also transport the necessary heat of reaction. The reduced carrier (M) is then returned to the air reactor for regeneration, hence the term "looping." The net chemical reaction and energy release is identical to that of conventional combustion of the fuel. However, CO2 separation is easily achieved, the only operational penalty being the slight pressure losses required to circulate the carrier. CLC requires many unit operations involving gas-solid or granular flow. To utilize coal in the fuel reactor, in either a moving bed or bubbling fluidized bed, the granular flow is especially critical. The solid coal fuel must be heated by the recycled metal oxide, driving off moisture and volatile material. The remaining char must be gasified by H2O (or CO2), which is recycled from the product stream. The gaseous product of these reactions must then contact the MO before leaving the bed to obtain complete conversion to H2O and CO2. Further, the reduced M particles must be

  7. A hybrid solar and chemical looping combustion system for solar thermal energy storage

    International Nuclear Information System (INIS)

    Jafarian, Mehdi; Arjomandi, Maziar; Nathan, Graham J.

    2013-01-01

    Highlights: ► A novel solar–CLC hybrid system is proposed which integrates a CLC with solar thermal energy. ► The oxygen carrier particles are used as storage medium for thermal energy storage. ► A solar cavity reactor is proposed for fuel reactor. ► The absorbed solar energy is stored in the particles to produce a base heat load. -- Abstract: A novel hybrid of a solar thermal energy and a chemical looping combustion (CLC) system is proposed here, which employs the oxygen carrier particles in a CLC system to provide diurnal thermal energy storage for concentrated solar thermal energy. In taking advantage of the chemical and sensible energy storage systems that are an inherent part of a CLC system, this hybrid offers potential to achieve cost effective, base load power generation for solar energy. In the proposed system, three reservoirs have been added to a conventional CLC system to allow storage of the oxygen carrier particles, while a cavity solar receiver has been chosen for the fuel reactor. The performance of the system is evaluated using ASPEN PLUS software, with the model being validated using independent simulation result reported previously. Operating temperature, solar efficiency, solar fraction, exergy efficiency and the fraction of the solar thermal energy stored for a based load power generation application are reported.

  8. Metal ferrite oxygen carriers for chemical looping combustion of solid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Siriwardane, Ranjani V.; Fan, Yueying

    2017-01-31

    The disclosure provides a metal ferrite oxygen carrier for the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The metal ferrite oxygen carrier comprises MFe.sub.xO.sub.y on an inert support, where MFe.sub.xO.sub.y is a chemical composition and M is one of Mg, Ca, Sr, Ba, Co, Mn, and combinations thereof. For example, MFe.sub.xO.sub.y may be one of MgFe.sub.2O.sub.4, CaFe.sub.2O.sub.4, SrFe.sub.2O.sub.4, BaFe.sub.2O.sub.4, CoFe.sub.2O.sub.4, MnFeO.sub.3, and combinations thereof. The MFe.sub.xO.sub.y is supported on an inert support. The inert support disperses the MFe.sub.xO.sub.y oxides to avoid agglomeration and improve performance stability. In an embodiment, the inert support comprises from about 5 wt. % to about 60 wt. % of the metal ferrite oxygen carrier and the MFe.sub.xO.sub.y comprises at least 30 wt. % of the metal ferrite oxygen carrier. The metal ferrite oxygen carriers disclosed display improved reduction rates over Fe.sub.2O.sub.3, and improved oxidation rates over CuO.

  9. Chemicals-Based Formulation Design: Virtual Experimentations

    DEFF Research Database (Denmark)

    Conte, Elisa; Gani, Rafiqul

    2011-01-01

    This paper presents a systematic procedure for virtual experimentations related to the design of liquid formulated products. All the experiments that need to be performed when designing a liquid formulated product (lotion), such as ingredients selection and testing, solubility tests, property...... measurements, can now be performed through the virtual Product-Process Design laboratory [[1], [2] and [3

  10. Particulate Formation from a Copper Oxide-Based Oxygen Carrier in Chemical Looping Combustion for CO2 Capture

    Science.gov (United States)

    Attrition behavior and particle loss of a copper oxide-based oxygen carrier from a methane chemical looping combustion (CLC) process was investigated in a fluidized bed reactor. The aerodynamic diameters of most elutriated particulates, after passing through a horizontal settling...

  11. A reduced fidelity model for the rotary chemical looping combustion reactor

    KAUST Repository

    Iloeje, Chukwunwike O.

    2017-01-11

    The rotary chemical looping combustion reactor has great potential for efficient integration with CO capture-enabled energy conversion systems. In earlier studies, we described a one-dimensional rotary reactor model, and used it to demonstrate the feasibility of continuous reactor operation. Though this detailed model provides a high resolution representation of the rotary reactor performance, it is too computationally expensive for studies that require multiple model evaluations. Specifically, it is not ideal for system-level studies where the reactor is a single component in an energy conversion system. In this study, we present a reduced fidelity model (RFM) of the rotary reactor that reduces computational cost and determines an optimal combination of variables that satisfy reactor design requirements. Simulation results for copper, nickel and iron-based oxygen carriers show a four-order of magnitude reduction in simulation time, and reasonable prediction accuracy. Deviations from the detailed reference model predictions range from 3% to 20%, depending on oxygen carrier type and operating conditions. This study also demonstrates how the reduced model can be modified to deal with both optimization and design oriented problems. A parametric study using the reduced model is then applied to analyze the sensitivity of the optimal reactor design to changes in selected operating and kinetic parameters. These studies show that temperature and activation energy have a greater impact on optimal geometry than parameters like pressure or feed fuel fraction for the selected oxygen carrier materials.

  12. Design of a rotary reactor for chemical-looping combustion. Part 1: Fundamentals and design methodology

    KAUST Repository

    Zhao, Zhenlong

    2014-04-01

    Chemical-looping combustion (CLC) is a novel and promising option for several applications including carbon capture (CC), fuel reforming, H 2 generation, etc. Previous studies demonstrated the feasibility of performing CLC in a novel rotary design with micro-channel structures. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet, and depleted air and product streams at exit. The rotary wheel consists of a large number of micro-channels with oxygen carriers (OC) coated on the inner surface of the channel walls. In the CC application, the OC oxidizes the fuel while the channel is in the fuel zone to generate undiluted CO2, and is regenerated while the channel is in the air zone. In this two-part series, the effect of the reactor design parameters is evaluated and its performance with different OCs is compared. In Part 1, the design objectives and criteria are specified and the key parameters controlling the reactor performance are identified. The fundamental effects of the OC characteristics, the design parameters, and the operating conditions are studied. The design procedures are presented on the basis of the relative importance of each parameter, enabling a systematic methodology of selecting the design parameters and the operating conditions with different OCs. Part 2 presents the application of the methodology to the designs with the three commonly used OCs, i.e., nickel, copper, and iron, and compares the simulated performances of the designs. © 2013 Elsevier Ltd. All rights reserved.

  13. Exergy analysis of methane cracking thermally coupled with chemical looping combustion for hydrogen production

    International Nuclear Information System (INIS)

    Wang, Zhe; Fan, Weiyu; Zhang, Guangqing; Dong, Shuang

    2016-01-01

    Highlights: • A novel MC–CLC process for H 2 production is proposed. • Energy utilisation of three MC processes is analysed by exergy analysis. • MC–CLC has the highest exergy efficiency compared with MC-CH 4 and MC-H 2. • MC-H 2 provides an advantage of absence of CO 2 generation. - Abstract: This paper proposes a novel hydrogen production process by Methane Cracking thermally coupled with Chemical Looping Combustion (MC–CLC) which provides an advantage of inherent capture of CO 2 . The energy utilisation performance of the MC–CLC process is compared with that of conventional Methane Cracking with combusting CH 4 (MC-CH 4 ) and Methane Cracking with combusting H 2 (MC-H 2 ) using exergy analysis, with focus on exergy flows, destruction and efficiency. The three MC processes are simulated using Aspen Plus software with detailed heat integration. In these processes, the majority of the exergy destruction occurs in the combustors or CLC mostly due to the high irreversibility of combustion. The CO 2 capture unit has the lowest exergy efficiency in the MC-CH 4 process, leading to a lower overall exergy efficiency of the process. The combustor in the MC-H 2 process has a much higher energy efficiency than that in the MC-CH 4 process or the CLC in the MC–CLC process. Although the use of H 2 as fuel decreases the H 2 production rate, the MC-H 2 process provides the advantage of an absence of CO 2 generation, and stores more chemical exergy in the solid carbon which can be utilised appropriately. The MC–CLC process obtains the highest exergy efficiency among the three models and this is primarily due to the absence of a CO 2 capture penalty and the CLC’s higher fuel utilization efficiency than the conventional combustion process.

  14. Utilization of the RELAP4 in the experimental water loop of the IPEN-CNEN/SP

    International Nuclear Information System (INIS)

    Sabundjian, G.

    1991-09-01

    For a better security of the nuclear power station and the population, thermal hydraulics codes for accident analysis were developed. Within all codes, the RELAP4, developed by Aerojet Nuclear Company of the Idaho Falls Engineering Laboratory (U.S.A.), has been the more used mostly by the fact of been available to the public. These code presents the most satisfactory results when used for various sort of problems. Basely the paper analyzes and compares the RELAP4/MOD3 and MOD5 versions, through the simulation on the Water Experimental Loop (C.E.A.) of the IPEN, in the steady state and in accidents conditions. Although the C.E.A. had been constructed to simulate PWR and BWR reactors, in these paper the tests were made only for PWR. Through the results analysis found in these paper, we concluded that the model adaptation for the simulations made with the RELAP4 code (version MOD3 and MOD5), were satisfactory. The accidents simulations indicates that the C.E.A. can support accident situation with the emergency system acting. Comparing the two versions, the MOD5 presented the better results compared with the real estimations. (author)

  15. Experimental analysis of the natural convection system through a closed loop under transient regime

    International Nuclear Information System (INIS)

    Lavrador, Marcelo de Bastos; Braga, Carlos Valois Maciel; Carajilescov, Pedro

    1996-01-01

    This work presents the experimental model used in the study of closed loop natural convection (thermosyphons). Details of the main circuit and information on the used instrumentation are also presented. The study aimed the circuit thermal performance, initially justifying the oscillatory behaviour of the time vs. temperature curves. As expected, the curves for the cold leg presented an oscillation amplitude lesser than those for hot leg since the 'peaks' which reveal high temperature spots disappear due to the heat transfer to the cooling water. Those curves were not influenced within the measured range, by the changes occurred in the cooling water flow (secondary circuit). Besides, when varying the power supplied by the hot source it was observed a variation directly proportional of the oscillation frequency, of the oscillation amplitude, and the difference between the hot and cold legs temperatures. Concerning to the forced power variations, it is observed that the oscillation is always restarted and the final results are related to the second applied power

  16. An experimental study of two-phase natural circulation in an adiabatic flow loop

    International Nuclear Information System (INIS)

    Tan, M.J.; Lambert, G.A.; Ishii, Mamoru.

    1988-01-01

    An experimental investigation was conducted to study the two-phase flow aspect of the phenomena of interruption and resumption of natural circulation, two-phase flow patterns and pattern transitions in the hot legs of B and W light water reactor systems. The test facility was a scaled adiabatic loop designed in accordance with the scaling criteria developed by Kocamustafaogullari and Ishii. The diameter and the height of the hot leg were 10 cm and 5.5 m, respectively; the working fluid pair was nitrogen-water. The effects of the thermal center in the steam generators, friction loss in the cold leg, and configuration of the inlet to the hot leg on the flow conditions in the hot leg were investigated by varying the water level in a gas separator, controlling the size of opening of a friction loss control valve, and using two inlet geometries. Methods for estimating the distribution parameter and the average drift velocity are proposed so that they may be used in the application of one-dimensional drift-flux model to the analysis of the interruption and resumption of natural circulation in a similar geometry. 7 refs., 17 figs., 4 tabs

  17. Chemical and radiation carcinogenesis in man and experimental animals

    International Nuclear Information System (INIS)

    Miller, J.A.; Miller, E.C.

    1975-01-01

    It is now well established that some cancer in man results from exposures to certain chemicals and radiations, both ultraviolet and ionizing radiations. These chemical and physical agents are also carcinogenic in experimental animals and, where adequately tested, in mammalian cell cultures. However, only very limited data are available on the relative roles of and the interrelationships, if any, between these various environmental agents in the causation of the majority of the cancers in man. Nothing is known of the relationship between these agents and possible carcinogenic viral information in the etiology of cancer in man. Furthermore, little is known about the molecular mechanisms by which chemicals and radiations induce cancers in either man or experimental animals. The objective of this brief review is to present certain aspects of chemical and radiation carcinogenesis in man and experimental animals and some of the problems in the elucidation of their roles in carinogenesis in the human

  18. Coupling of high temperature nuclear reactor with chemical plant by means of steam loop with heat pump

    Directory of Open Access Journals (Sweden)

    Kopeć Mariusz

    2017-01-01

    Full Text Available High temperature nuclear reactors (HTR can be used as an excellent, emission-free source of technological heat for various industrial applications. Their outlet helium temperature (700°-900°C allows not only for heat supply to all processes below 600°C (referred to as “steam class”, but also enables development of clean nuclear-assisted hydrogen production or coal liquefaction technologies with required temperatures up to 900°C (referred to as “chemical class”. This paper presents the results of analyses done for various configurations of the steam transport loop coupled with the high-temperature heat pump designed for “chemical class” applications. The advantages and disadvantages as well as the key issues are discussed in comparison with alternative solutions, trying to answer the question whether the system with the steam loop and the hightemperature heat pump is viable and economically justified.

  19. Comparison of iron-, nickel-, copper- and manganese-based oxygen carriers for chemical-looping combustion

    Energy Technology Data Exchange (ETDEWEB)

    Paul Cho; Tobias Mattisson; Anders Lyngfelt [Chalmers University of Technology, Goeteborg (Sweden). Department of Environmental Inorganic Chemistry

    2004-06-01

    For combustion with CO{sub 2} capture, chemical-looping combustion (CLC) with inherent separation of CO{sub 2} is a promising technology. Two interconnected fluidized beds are used as reactors. In the fuel reactor, a gaseous fuel is oxidized by an oxygen carrier, e.g. metal oxide particles, producing carbon dioxide and water. The reduced oxygen carrier is then transported to the air reactor, where it is oxidized with air back to its original form before it is returned to the fuel reactor. The feasibility of using oxygen carrier based on oxides of iron, nickel, copper and manganese was investigated. Oxygen carrier particles were produced by freeze granulation. They were sintered at 1300{sup o}C for 4 h and sieved to a size range of 125-180 {mu}m. The reactivity of the oxygen carriers was evaluated in a laboratory fluidized bed reactor, simulating a CLC system by exposing the sample to alternating reducing and oxidizing conditions at 950{sup o}C for all carriers except copper, which was tested at 850{sup o}C. Oxygen carriers based on nickel, copper and iron showed high reactivity, enough to be feasible for a suggested CLC system. However, copper oxide particles agglomerated and may not be suitable as an oxygen carrier. Samples of the iron oxide with aluminium oxide showed signs of agglomeration. Nickel oxide showed the highest reduction rate, but displayed limited strength. The reactivity indicates a needed bed mass in the fuel reactor of about 80-330 kg/MW{sub th} and a needed recirculation flow of oxygen carrier of 4-8 kg/s, MW{sub th}. 30 refs., 7 figs., 6 tabs.

  20. Chemical-looping combustion in a reverse-flow fixed bed reactor

    International Nuclear Information System (INIS)

    Han, Lu; Bollas, George M.

    2016-01-01

    A reverse-flow fixed bed reactor concept for CLC (chemical-looping combustion) is explored. The limitations of conventional fixed bed reactors, as applied to CLC, are overcome by reversing the gas flow direction periodically to enhance the mixing characteristics of the bed, thus improving oxygen carrier utilization and energy efficiency with respect to power generation. The reverse-flow reactor is simulated by a dusty-gas model and compared with an equivalent fixed bed reactor without flow reversal. Dynamic optimization is used to calculate conditions at which each reactor operates at maximum energy efficiency. Several cases studies illustrate the benefits of reverse-flow operation for the CLC with CuO and NiO oxygen carriers and methane and syngas fuels. The results show that periodic reversal of the flow during reduction improves the contact between the fuel and unconverted oxygen carrier, enabling the system to suppress unwanted catalytic reactions and axial temperature and conversion gradients. The operational scheme presented reduces the fluctuations of temperature during oxidation and increases the high-temperature heat produced by the process. CLC in a reverse-flow reactor has the potential to achieve higher energy efficiency than conventional fixed bed CLC reactors, when integrated with a downstream gas turbine of a combined cycle power plant. - Highlights: • Reverse-flow fixed bed CLC reactors for combined cycle power systems. • Dynamic optimization tunes operation of batch and transient CLC systems. • The reverse-flow CLC system provides stable turbine-ready gas stream. • Reverse-flow CLC fixed bed reactor has superior CO 2 capture and thermal efficiency.

  1. Analysis of thermally coupled chemical looping combustion-based power plants with carbon capture

    KAUST Repository

    Iloeje, Chukwunwike

    2015-04-01

    © 2015 Elsevier Ltd. A number of CO2 capture-enabled power generation technologies have been proposed to address the negative environmental impact of CO2 emission. One important barrier to adopting these technologies is the associated energy penalty. Chemical-looping Combustion (CLC) is an oxy-combustion technology that can significantly lower this penalty. It utilizes an oxygen carrier to transfer oxygen from air/oxidizing stream in an oxidation reactor to the fuel in a reduction reactor. Conventional CLC reactor designs employ two separate reactors, with metal/metal oxide particles circulating pneumatically in-between. One of the key limitations of these designs is the entropy generation due to reactor temperature difference, which lowers the cycle efficiency. Zhao et al. (Zhao et al., 2014; Zhao and Ghoniem, 2014) proposed a new CLC rotary reactor design, which overcomes this limitation. This reactor consists of a single rotating wheel with micro-channels designed to maintain thermal equilibrium between the fuel and air sides. This study uses three thermodynamic models of increasing fidelity to demonstrate that the internal thermal coupling in the rotary CLC reactor creates the potential for improved cycle efficiency. A theoretical availability model and an ideal thermodynamic cycle model are used to define the efficiency limits of CLC systems, illustrate the impact of reactor thermal coupling and discuss relevant criteria. An Aspen Plus® model of a regenerative CLC cycle is then used to show that this thermal coupling raises the cycle efficiency by up to 2% points. A parametric study shows that efficiency varies inversely with pressure, with a maximum of 51% at 3bar, 1000C and 60% at 4bar, 1400C. The efficiency increases with CO2 fraction at high pressure ratios but exhibits a slight inverse dependence at low pressure ratios. The parametric study shows that for low purge steam demand, steam generation improves exhaust heat recovery and increases efficiency

  2. EXPERIMENTAL AND SIMULATION ANALYSIS OF BREAKLOCK IN PHASE LOCKED LOOP SYNTHESIZER FOR FREQUENCY TRACKING APPLICATIONS

    Directory of Open Access Journals (Sweden)

    HARIKRISHNA PAIK

    2017-02-01

    Full Text Available Modern missile seekers invariably employ monopulse radar with phase locked loop (PLL as a frequency (angle tracking subsystem in the receiver. The frequency locking and/or unlocking of these receivers can be achieved either by introducing imperfections in the monopulse design or using multiple repeater sources. In the present paper, the break-lock of PLL synthesizer in the monopulse radar receiver is presented. The linear frequency modulated (LFM signal has been used as a repeater interference signal, which is injected into the PLL along with radar echo signal. The frequency deviation as a function of LFM signal power required to break-lock is presented for different values of modulation rate and echo signal power. The simulation results show that breaklock is achieved at frequency deviation of 0.36 MHz (0.35 MHz measured value for a typical jammer power of -14 dBm and modulation rate of 200 kHz with radar echo signal power of -14 dBm at the PLL input. The measured results show that at a typical jammer power of -14 dBm, break-lock is achieved at frequency deviations of 0.35 and 0.9 MHz for modulation rates of 200 and 500 kHz respectively, revealing that at lower values of modulation rate, breaklock is achieved at lower values of frequency deviation. The computer simulation is carried out for performance prediction and experimental measurement results are presented in support of the simulated results. With fairly good and consistent agreement between the measured and simulated results, the PLL is well suited to be integrated within monopulse radar receivers for LFM jamming.

  3. Determining the Properties and Capabilities of an Existing Experimental Large Loop EM61 Underwater UXO Detector

    National Research Council Canada - National Science Library

    2006-01-01

    ... minimized. Dillon Consulting Limited, with assistance from Geonics Limited, modified a high power Geonics EM61-MK2 System by adding a large primary loop transmitter floating on a barge and a submerged receiver...

  4. Chemical Looping Gasification for Hydrogen Enhanced Syngas Production with In-Situ CO2 Capture

    Energy Technology Data Exchange (ETDEWEB)

    Kathe, Mandar [Ohio State University, Columbus, OH (United States); Xu, Dikai [Ohio State University, Columbus, OH (United States); Hsieh, Tien-Lin [Ohio State University, Columbus, OH (United States); Simpson, James [Ohio State University, Columbus, OH (United States); Statnick, Robert [Ohio State University, Columbus, OH (United States); Tong, Andrew [Ohio State University, Columbus, OH (United States); Fan, Liang-Shih [Ohio State University, Columbus, OH (United States)

    2014-12-31

    This document is the final report for the project titled “Chemical Looping Gasification for Hydrogen Enhanced Syngas Production with In-Situ CO2 Capture” under award number FE0012136 for the performance period 10/01/2013 to 12/31/2014.This project investigates the novel Ohio State chemical looping gasification technology for high efficiency, cost efficiency coal gasification for IGCC and methanol production application. The project developed an optimized oxygen carrier composition, demonstrated the feasibility of the concept and completed cold-flow model studies. WorleyParsons completed a techno-economic analysis which showed that for a coal only feed with carbon capture, the OSU CLG technology reduced the methanol required selling price by 21%, lowered the capital costs by 28%, increased coal consumption efficiency by 14%. Further, using the Ohio State Chemical Looping Gasification technology resulted in a methanol required selling price which was lower than the reference non-capture case.

  5. Hydrogen production from natural gas using an iron-based chemical looping technology: Thermodynamic simulations and process system analysis

    International Nuclear Information System (INIS)

    Kathe, Mandar V.; Empfield, Abbey; Na, Jing; Blair, Elena; Fan, Liang-Shih

    2016-01-01

    Highlights: • Design of iron-based chemical looping process using moving bed for H 2 from CH 4 . • Auto-thermal operation design using thermodynamic rationale for 90% carbon capture. • Cold gas efficiency: 5% points higher than Steam Methane Reforming baseline case. • Net thermal efficiency: 6% points higher than Steam Methane Reforming baseline case. • Sensitivity analysis: Energy recovery scheme, operating pressure, no carbon capture. - Abstract: Hydrogen (H 2 ) is a secondary fuel derived from natural gas. Currently, H 2 serves as an important component in refining operations, fertilizer production, and is experiencing increased utilization in the transportation industry as a clean combustion fuel. In recent years, industry and academia have focused on developing technology that reduces carbon emissions. As a result, there has been an increase in the technological developments for producing H 2 from natural gas. These technologies aim to minimize the cost increment associated with clean energy production. The natural gas processing chemical looping technology, developed at The Ohio State University (OSU), employs an iron-based oxygen carrier and a novel gas–solid counter-current moving bed reactor for H 2 production. Specifically, this study examines the theoretical thermodynamic limits for full conversion of natural gas through iron-based oxygen carrier reactions with methane (CH 4 ), by utilizing simulations generated with ASPEN modeling software. This study initially investigates the reducer and the oxidizer thermodynamic phase diagrams then derives an optimal auto-thermal operating condition for the complete loop simulation. This complete loop simulation is initially normalized for analysis on the basis of one mole of carbon input from natural gas. The H 2 production rate is then scaled to match that of the baseline study, using a full-scale ASPEN simulation for computing cooling loads, water requirements and net parasitic energy consumption. The

  6. Experimental and analytical study of steady state natural circulation with throughflow in a figure-of-eight loop

    International Nuclear Information System (INIS)

    Vijayan, P.K.; Mehta, S.K.; Date, A.W.

    1990-01-01

    The one dimensional energy and momentum conservation equations applicable to thermosyphon with throughflow are solved with suitable assumptions for a figure-of-eight loop and analytical solutions are obtained for the steady state case for different throughflow inlet and outlet points. It is also examined whether hot leg or cold leg injection is preferred for the nuclear reactors during thermosyphon with throughflow. Comparison of predicted steady state flow rates with experimental data shows agreement within +15%. (author). 14 refs., 9 figs

  7. Transient analysis of mercury experimental loop using the RELAP5 code. 3rd report. Transient analysis using mercury properties

    International Nuclear Information System (INIS)

    Kinoshita, Hidetaka; Kaminaga, Masanori; Hino, Ryutaro

    2000-02-01

    In order to promote the Neutron Science Project of JAERI, the design of a 5MW-spallation target system is in progress with the purpose of producing a practical neutron application while at the same time adhering to the highest levels of safety. To establish the safety of the target system, it is important to understand the transient behaviors during anticipated operational events of the system, and to design the safety protection systems for the safe termination of the transients. This report presents the analytical results of transient behaviors in the mercury experimental loop using mercury properties. At first, the analytical pressure distributions were compared with experimental data measured with the mercury experimental loop. The modeling data were modified to reproduce the actual pressure distributions of the mercury experimental loop. Then a loss of forced convection and a loss of coolant accident were analyzed. In the case of the pump trip, the transient analysis was conducted using two types of mercury pumps, the mechanical type pump with moment of inertia, and the electrical-magnetic type pump without moment of inertia. The results show there was no clear difference in the two analyses, since the mercury had a large inertia, which was 13.5 times that of the water. Moreover, in the case of a pipe rupture at the pump exit, a moderate pressure decrease was confirmed when a small breakage area existed in which the coolant flowed out gradually. Based on these results, it was appeared that the transient fluctuation of pressure in the mercury loop would not become large and accidents would have to be detected by small fluctuations in pressure. Based on these analyses, we plan to conduct a simulation test to verify the RELAP5 code, and then the analysis of a full-scale mercury system will be performed. (author)

  8. On the evaluation of synthetic and natural ilmenite using syngas as fuel in chemical-looping combustion (CLC)

    Energy Technology Data Exchange (ETDEWEB)

    Azis, M.M.; Jerndal, E.; Leion, H.; Mattisson, T.; Lyngfelt, A. [Chalmers, Gothenburg (Sweden)

    2010-11-15

    Chemical-looping combustion (CLC) is a combustion technique where the CO{sub 2} produced is inherently separated from the rest of the flue gases with a considerably low energy penalty. For this reason, CLC has emerged as one of the more attractive options to capture CO{sub 2} from fossil fuel combustion. When applying CLC with solid fuels, the use of a low cost oxygen carrier is highly important, and one such low cost oxygen carrier is the mineral ilmenite. The current work investigates the reactivity of several ilmenites, some which are synthetically produced by freeze granulation and two natural minerals, one Norwegian ilmenite and one South African ilmenite. A laboratory fluidized bed reactor made of quartz was used to simulate a two reactor CLC system by alternating the reduction and oxidation phase. The fuel was syngas containing 50% CO and 50% H{sub 2}. A mixture of 6g of ilmenite with 9 g inert quartz of diameter 125-180 {mu} m was exposed to a flow of 900mL{sup n}/min syngas in the reduction phase. During the oxidation phase, a 900mL/{sub n}min flow of 10% O{sub 2} diluted in N{sub 2} was used. The experimental results showed that all ilmenites give higher conversion of H{sub 2} than of CO. Generally, synthetic ilmenites have better CO and H{sub 2} conversion than natural ilmenites and synthetic ilmenites prepared with an excess of Fe generally showed higher total conversion of CO than synthetic ilmenites with an excess of Ti. Most synthetic ilmenites and the Norwegian ilmenite showed good fluidization properties during the experiments. However, for two of the synthetically produced materials, and for the South African ilmenite, particle agglomerations were visible at the end of the experiment.

  9. Performance of calcium manganate as oxygen carrier in chemical looping combustion of biochar in a 10 kW pilot

    International Nuclear Information System (INIS)

    Schmitz, Matthias; Linderholm, Carl Johan

    2016-01-01

    Highlights: • A manganese-based perovskite material was used as oxygen carrier in chemical looping combustion. • The oxygen carrier’s performance was superior to materials previously tested in this reactor throughout the testing period. • Under stable conditions, oxygen demand was as low as 2.1% with a carbon capture efficiency of up to 98%. • No signs of agglomeration were detected. • Gaseous oxygen was released at all relevant fuel reactor temperatures. - Abstract: Chemical looping combustion (CLC) and chemical looping with oxygen uncoupling (CLOU) are carbon capture technologies which achieve gas separation by means of cycling oxidation and reduction of a solid oxygen carrier. In this study, the performance and CLOU properties of an oxygen carrier with perovskite structure, CaMn 0.9 Mg 0.1 O 3−δ, were investigated in a 10 kW pilot. The fuel consisted of biochar with very low sulphur content. Around 37 h of operation with fuel were carried out in the 10 kW chemical looping combustor. Previous operational experience in this unit has been achieved using different natural minerals as oxygen carrier – mainly ilmenite and manganese ore. Parametric studies performed in this work included variation of fuel flow, solids circulation rate, temperature and fluidization gas in the fuel reactor. The oxygen carrier was exposed to a total 73 h of hot fluidization (T > 600 °C). No hard particle agglomerations were formed during the experiments. An oxygen demand as low as 2.1% could be reached under stable operating conditions, with a carbon capture efficiency of up to 98%. CLOU properties were observed at all fuel reactor temperatures, ensuring stable operation even without steam as gasification agent present in the fuel reactor. The results suggest that CaMn 0.9 Mg 0.1 O 3−δ is suitable for the use as oxygen carrier in chemical looping combustion of solid biochar and offers higher gas conversion than previously tested materials without CLOU properties such

  10. Algorithms for a Single Hormone Closed-Loop Artificial Pancreas: Challenges Pertinent to Chemical Process Operations and Control

    Directory of Open Access Journals (Sweden)

    B. Wayne Bequette

    2016-10-01

    Full Text Available The development of a closed-loop artificial pancreas to regulate the blood glucose concentration of individuals with type 1 diabetes has been a focused area of research for over 50 years, with rapid progress during the past decade. The daily control challenges faced by someone with type 1 diabetes include asymmetric objectives and risks, and one-sided manipulated input action with frequent relatively fast disturbances. The major automation steps toward a closed-loop artificial pancreas include (i monitoring and overnight alarms for hypoglycemia (low blood glucose; (ii overnight low glucose suspend (LGS systems to prevent hypoglycemia; and (iii fully closed-loop systems that adjust insulin (and perhaps glucagon to maintain desired blood glucose levels day and night. We focus on the steps that we used to develop and test a probabilistic, risk-based, model predictive control strategy for a fully closed-loop artificial pancreas. We complete the paper by discussing ramifications of lessons learned for chemical process systems applications.

  11. Design and Experimental Evaluation of Modified Square Loop Feeding for UHF RFID Tags.

    Directory of Open Access Journals (Sweden)

    Md Rokunuzzaman

    Full Text Available This paper addresses the performance evaluation of a modified square loop antenna design for UHF RFID applications that is excited through a narrow feed line connected to a square loop, an impedance matching network. The square loop dimensions are modified to reach a conjugate impedance matching. A gap is fixed between the feed-lines to link the chip. To achieve impedance matching, the structures of the feed-line are optimized accordingly. In addition, the antenna consists of a straightforward geometry. An 11.9-meter maximum read range is achieved using a compact size of 80 × 44 mm2 and 3.2 W for the effective isotropic radiated power. Additional findings reveal that the proposed tag antenna is able to provide a stable resonance response in the near field of a large metallic surface.

  12. Experimental setup for rapid crystallization using favoured chemical ...

    Indian Academy of Sciences (India)

    Unknown

    sent paper we describe a small scale experimental setup for rapid crystallization in which growth is favoured by chemical potential and hydrodynamic conditions. Using this we have grown KH2PO4 (KDP) single crystals up to. 40 × 43 × 66 mm3 in dimensions on a point seed in a glass crystallizer of 5 l capacity in about 72 h.

  13. Mechanism of Methane Chemical Looping Combustion with Hematite Promoted with CeO 2

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Duane D.; Siriwardane, Ranjani

    2013-08-15

    Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion that produces sequestration-ready CO{sub 2} stream, reducing the energy penalty of CO{sub 2} separation from flue gases. An effective oxygen carrier for CLC will readily react with the fuel gas and will be reoxidized upon contact with oxygen. This study investigated the development of a CeO{sub 2}-promoted Fe{sub 2}O{sub 3}-hematite oxygen carrier suitable for the methane CLC process. Composition of CeO{sub 2} is between 5 and 25 wt % and is lower than what is generally used for supports in Fe{sub 2}O{sub 3} carrier preparations. The incorporation of CeO{sub 2} to the natural ore hematite strongly modifies the reduction behavior in comparison to that of CeO{sub 2} and hematite alone. Temperature-programmed reaction studies revealed that the addition of even 5 wt % CeO{sub 2} enhances the reaction capacity of the Fe{sub 2}O{sub 3} oxygen carrier by promoting the decomposition and partial oxidation of methane. Fixed-bed reactor data showed that the 5 wt % cerium oxides with 95 wt % iron oxide produce 2 times as much carbon dioxide in comparison to the sum of carbon dioxide produced when the oxides were tested separately. This effect is likely due to the reaction of CeO{sub 2} with methane forming intermediates, which are reactive for extracting oxygen from Fe{sub 2}O{sub 3} at a considerably faster rate than the rate of the direct reaction of Fe{sub 2}O{sub 3} with methane. These studies reveal that 5 wt % CeO{sub 2}/Fe{sub 2}O{sub 3} gives stable conversions over 15 reduction/oxidation cycles. Lab-scale reactor studies (pulsed mode) suggest the methane reacts initially with CeO{sub 2} lattice oxygen to form partial oxidation products (CO + H{sub 2}), which continue to react with oxygen from neighboring Fe{sub 2}O{sub 3}, leading to its complete oxidation to form CO{sub 2}. The reduced cerium oxide promotes the methane decomposition reaction to form C + H{sub 2}, which continue to

  14. Investigation on reactivity of iron nickel oxides in chemical looping dry reforming

    International Nuclear Information System (INIS)

    Huang, Zhen; He, Fang; Chen, Dezhen; Zhao, Kun; Wei, Guoqiang; Zheng, Anqing; Zhao, Zengli; Li, Haibin

    2016-01-01

    Iron nickel oxides as oxygen carriers were investigated to clarify the reaction mechanism of NiFe 2 O 4 material during the chemical looping dry reforming (CLDR) process. The thermodynamic analysis showed that metallic Fe can be oxidized into Fe 3 O 4 by CO 2 , but metallic Ni cannot. The oxidizability of the four oxygen carriers was in the order of NiO > synthetic NiFe 2 O 4 spinel > NiO-Fe 2 O 3 mixed oxides > Fe 2 O 3 , and the reducibility sequence of their reduced products was synthetic NiFe 2 O 4 spinel > NiO-Fe 2 O 3 mixed oxides > Fe 2 O 3  > NiO. The NiO showed the best oxidizability but it was easy to cause CH 4 cracking and its reduced product (Ni) did not recover lattice oxygen under CO 2 atmosphere. It only produced 74 mL CO for 1 g Fe 2 O 3 during the CO 2 reforming because of its weak oxidizability. The Redox ability of synthetic NiFe 2 O 4 was obvious higher than that of NiO-Fe 2 O 3 mixed oxides due to the synergistic effect of metallic Fe-Ni in the spinel structure. 1 g synthetic NiFe 2 O 4 can produce 238 mL CO, which was twice higher than that of 1 g NiO-Fe 2 O 3 mixed oxides (111 mL). A part of Fe element was divorced from the NiFe 2 O 4 spinel structure after one cycle, which was the major reason for degradation of reactivity of NiFe 2 O 4 oxygen carrier. - Highlights: • A synergistic effect of Fe/Ni can improve the reactivity of oxygen carrier (OC). • The oxidizability sequence of four OCs is NiO > NiFe 2 O 4  > mixed NiO + Fe 2 O 3  > Fe 2 O 3 . • The reducibility sequence of four OCs is NiFe 2 O 4  > mixed NiO + Fe 2 O 3  > Fe 2 O 3  > NiO. • The formation of Fe (Ni) alloy phase facilitates more CO 2 reduced into CO. • Part of Fe is divorced from the spinel structure, leading to the degeneration of OC reactivity.

  15. Impact of mixing chemically heterogeneous groundwaters on the sustainability of an open-loop groundwater heat pump

    Science.gov (United States)

    Burté, L.; Farasin, J.; Cravotta, C., III; Gerard, M. F.; Cotiche Baranger, C.; Aquilina, L.; Le Borgne, T.

    2017-12-01

    Geothermal systems using shallow aquifers are commonly used for heating and cooling. The sustainability of these systems can be severely impacted by the occurrence of clogging process. The geothermal loop operation (including pumping of groundwater, filtering and heat extraction through exchangers and cooled water injection) can lead to an unexpected biogeochemical reactivity and scaling formation that can ultimately lead to the shutdown of the geothermal doublet. Here, we report the results of investigations carried out on a shallow geothermal doublet (dynamic). Hydrochemical data collected at the pumping well showed that groundwater was chemically heterogeneous long the 11 meters well screen. While the aquifer was dominantly oxic, a localized inflow of anoxic water was detected and evaluated to produce about 40% of the total flow . The mixture of chemically heterogeneous water induced by pumping lead to the oxidation of reductive species and thus to the formation of biogenic precipitates responsible for clogging. The impact of pumping waters of different redox potential and chemical characteristics was quantified by numerical modeling using PHREEQC. These results shows that natural chemical heterogeneity can occur at a small scale in heterogeneous aquifers and highlight the importance of their characterization during the production well testing and the geothermal loop operation in order to take preventive measures to avoid clogging.

  16. Sulfur evolution in chemical looping combustion of coal with MnFe2O4 oxygen carrier.

    Science.gov (United States)

    Wang, Baowen; Gao, Chuchang; Wang, Weishu; Zhao, Haibo; Zheng, Chuguang

    2014-05-01

    Chemical looping combustion (CLC) of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier (OC) was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi (LZ) bituminous coal, was performed in a thermogravimetric analyzer (TGA)-Fourier transform infrared (FT-IR) spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFe2O4 OC was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn3O4 or Fe2O3, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe3O4 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  17. Emil Fischer and the "art of chemical experimentation".

    Science.gov (United States)

    Jackson, Catherine M

    2017-03-01

    What did nineteenth-century chemists know? This essay uses Emil Fischer's classic study of the sugars in 1880s and 90s Germany to argue that chemists' knowledge was not primarily vested in the theories of valence, structure, and stereochemistry that have been the subject of so much historical and philosophical analysis of chemistry in this period. Nor can chemistry be reduced to a merely manipulative exercise requiring little or no intellectual input. Examining what chemists themselves termed the "art of chemical experimentation" reveals chemical practice as inseparable from its cognitive component, and it explains how chemists integrated theory with experiment through reason.

  18. Thermodynamic analysis of in situ gasification-chemical looping combustion (iG-CLC) of Indian coal.

    Science.gov (United States)

    Suresh, P V; Menon, Kavitha G; Prakash, K S; Prudhvi, S; Anudeep, A

    2016-10-01

    Chemical looping combustion (CLC) is an inherent CO 2 capture technology. It is gaining much interest in recent years mainly because of its potential in addressing climate change problems associated with CO 2 emissions from power plants. A typical chemical looping combustion unit consists of two reactors-fuel reactor, where oxidation of fuel occurs with the help of oxygen available in the form of metal oxides and, air reactor, where the reduced metal oxides are regenerated by the inflow of air. These oxides are then sent back to the fuel reactor and the cycle continues. The product gas from the fuel reactor contains a concentrated stream of CO 2 which can be readily stored in various forms or used for any other applications. This unique feature of inherent CO 2 capture makes the technology more promising to combat the global climate changes. Various types of CLC units have been discussed in literature depending on the type of fuel burnt. For solid fuel combustion three main varieties of CLC units exist namely: syngas CLC, in situ gasification-CLC (iG-CLC) and chemical looping with oxygen uncoupling (CLOU). In this paper, theoretical studies on the iG-CLC unit burning Indian coal are presented. Gibbs free energy minimization technique is employed to determine the composition of flue gas and oxygen carrier of an iG-CLC unit using Fe 2 O 3 , CuO, and mixed carrier-Fe 2 O 3 and CuO as oxygen carriers. The effect of temperature, suitability of oxygen carriers, and oxygen carrier circulation rate on the performance of a CLC unit for Indian coal are studied and presented. These results are analyzed in order to foresee the operating conditions at which economic and smooth operation of the unit is expected.

  19. Effects of intact loop hydraulic resistance of PWR LOCA behavior in scaled experimental facilities

    Energy Technology Data Exchange (ETDEWEB)

    Jacoby, M.S.

    1977-09-01

    The scaling of experiments in the Water Reactor Safety Program has been on a power/volume basis. This scaling philosophy has resulted in good thermal modeling of the core, but, combined with core design considerations, compromises the modeling of the hydraulic resistance in the intact loop. Tests in LOFT, Semiscale MOD-1 and FLECHT-SET have been conducted for the purpose of determining the effect of scaling hydraulic resistance to core area ratio (low hydraulic resistance) or to core power ratio (high hydraulic resistance). The results of these tests, together with computer model results using RELAP4/MOD5, RE-FRAP, and FLOOD4, were studied to determine the effects of the scaling compromise. The review of available information has shown no significant results of varying intact loop hydraulic resistance.

  20. Closed loop control of laser welding processes using cellular neural network cameras - experimental results

    OpenAIRE

    Abt, F.; Blug, A.; Nicolosi, L.; Dausinger, F.; Weber, R.; Tetzlaff, R.; Carl, D.; Höfler, H.

    2009-01-01

    Today, image processing using coaxial camera setups is used to monitor the quality of laser material processes such as laser welding, cutting or ablation. This article shows the potentials of a sensing system for the next step: A closed loop control of a full penetration keyhole welding process. With Cellular Neural Networks (CNN) it is possible to integrate processor elements in the electronic circuitry of CMOS cameras resulting in a Single-Instruction-Multiple-Data (SIMD)-architecture on th...

  1. Closed-loop, multichannel experimentation using the open-source NeuroRighter electrophysiology platform

    Directory of Open Access Journals (Sweden)

    Jonathan Paul Newman

    2013-01-01

    Full Text Available Single neuron feedback control techniques, such as voltage clamp and dynamic clamp, have enabled numerous advances in our understanding of ion channels, electrochemical signaling, and neural dynamics. Although commercially available multichannel recording and stimulation systems are commonly used for studying neural processing at the network level, they provide little native support for real-time feedback. We developed the open-source NeuroRighter multichannel electrophysiology hardware and software platform for closed-loop multichannel control with a focus on accessibility and low cost. NeuroRighter allows 64 channels of stimulation and recording for around US $10,000, along with the ability to integrate with other software and hardware. Here, we present substantial enhancements to the NeuroRighter platform, including a redesigned desktop application, a new stimulation subsystem allowing arbitrary stimulation patterns, low-latency data servers for accessing data streams, and a new application programming interface (API for creating closed-loop protocols that can be inserted into NeuroRighter as plugin programs. This greatly simplifies the design of sophisticated real-time experiments without sacrificing the power and speed of a compiled programming language. Here we present a detailed description of NeuroRighter as a stand alone application, its plugin API, and an extensive set of case studies that highlight the system's abilities for conducting closed-loop, multichannel interfacing experiments.

  2. Closed-Loop, Multichannel Experimentation Using the Open-Source NeuroRighter Electrophysiology Platform.

    Science.gov (United States)

    Newman, Jonathan P; Zeller-Townson, Riley; Fong, Ming-Fai; Arcot Desai, Sharanya; Gross, Robert E; Potter, Steve M

    2012-01-01

    Single neuron feedback control techniques, such as voltage clamp and dynamic clamp, have enabled numerous advances in our understanding of ion channels, electrochemical signaling, and neural dynamics. Although commercially available multichannel recording and stimulation systems are commonly used for studying neural processing at the network level, they provide little native support for real-time feedback. We developed the open-source NeuroRighter multichannel electrophysiology hardware and software platform for closed-loop multichannel control with a focus on accessibility and low cost. NeuroRighter allows 64 channels of stimulation and recording for around US $10,000, along with the ability to integrate with other software and hardware. Here, we present substantial enhancements to the NeuroRighter platform, including a redesigned desktop application, a new stimulation subsystem allowing arbitrary stimulation patterns, low-latency data servers for accessing data streams, and a new application programming interface (API) for creating closed-loop protocols that can be inserted into NeuroRighter as plugin programs. This greatly simplifies the design of sophisticated real-time experiments without sacrificing the power and speed of a compiled programming language. Here we present a detailed description of NeuroRighter as a stand-alone application, its plugin API, and an extensive set of case studies that highlight the system's abilities for conducting closed-loop, multichannel interfacing experiments.

  3. Calibration of the island effect: Experimental validation of closed-loop focal plane wavefront control on Subaru/SCExAO

    Science.gov (United States)

    N'Diaye, M.; Martinache, F.; Jovanovic, N.; Lozi, J.; Guyon, O.; Norris, B.; Ceau, A.; Mary, D.

    2018-02-01

    Context. Island effect (IE) aberrations are induced by differential pistons, tips, and tilts between neighboring pupil segments on ground-based telescopes, which severely limit the observations of circumstellar environments on the recently deployed exoplanet imagers (e.g., VLT/SPHERE, Gemini/GPI, Subaru/SCExAO) during the best observing conditions. Caused by air temperature gradients at the level of the telescope spiders, these aberrations were recently diagnosed with success on VLT/SPHERE, but so far no complete calibration has been performed to overcome this issue. Aims: We propose closed-loop focal plane wavefront control based on the asymmetric Fourier pupil wavefront sensor (APF-WFS) to calibrate these aberrations and improve the image quality of exoplanet high-contrast instruments in the presence of the IE. Methods: Assuming the archetypal four-quadrant aperture geometry in 8 m class telescopes, we describe these aberrations as a sum of the independent modes of piston, tip, and tilt that are distributed in each quadrant of the telescope pupil. We calibrate these modes with the APF-WFS before introducing our wavefront control for closed-loop operation. We perform numerical simulations and then experimental tests on a real system using Subaru/SCExAO to validate our control loop in the laboratory and on-sky. Results: Closed-loop operation with the APF-WFS enables the compensation for the IE in simulations and in the laboratory for the small aberration regime. Based on a calibration in the near infrared, we observe an improvement of the image quality in the visible range on the SCExAO/VAMPIRES module with a relative increase in the image Strehl ratio of 37%. Conclusions: Our first IE calibration paves the way for maximizing the science operations of the current exoplanet imagers. Such an approach and its results prove also very promising in light of the Extremely Large Telescopes (ELTs) and the presence of similar artifacts with their complex aperture geometry.

  4. Heat Integration of the Water-Gas Shift Reaction System for Carbon Sequestration Ready IGCC Process with Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Juan M. Salazara; Stephen E. Zitney; Urmila M. Diwekara

    2010-01-01

    Integrated gasification combined cycle (IGCC) technology has been considered as an important alternative for efficient power systems that can reduce fuel consumption and CO2 emissions. One of the technological schemes combines water-gas shift reaction and chemical-looping combustion as post gasification techniques in order to produce sequestration-ready CO2 and potentially reduce the size of the gas turbine. However, these schemes have not been energetically integrated and process synthesis techniques can be applied to obtain an optimal flowsheet. This work studies the heat exchange network synthesis (HENS) for the water-gas shift reaction train employing a set of alternative designs provided by Aspen energy analyzer (AEA) and combined in a process superstructure that was simulated in Aspen Plus (AP). This approach allows a rigorous evaluation of the alternative designs and their combinations avoiding all the AEA simplifications (linearized models of heat exchangers). A CAPE-OPEN compliant capability which makes use of a MINLP algorithm for sequential modular simulators was employed to obtain a heat exchange network that provided a cost of energy that was 27% lower than the base case. Highly influential parameters for the pos gasification technologies (i.e. CO/steam ratio, gasifier temperature and pressure) were calculated to obtain the minimum cost of energy while chemical looping parameters (oxidation and reduction temperature) were ensured to be satisfied.

  5. Inverted hysteresis loops: Experimental artifacts arising from inappropriate or asymmetric sample positioning and the misinterpretation of experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Jin Hanmin [Reserch Center for Advanced Magnetic Materials, Chungnam National University, 220, Gung-dong, Youseong-gu, Daejeon, 305-764 (Korea, Republic of) and Department of Physics, Jilin University, 119 Jiefang road, 130023, Changchun (China)]. E-mail: jinhanmin@jlu.edu.cn; Sun Dongsheng [Reserch Center for Advanced Magnetic Materials, Chungnam National University, 220, Gung-dong, Youseong-gu, Daejeon, 305-764 (Korea, Republic of); Gao Cunxu [Department of Materials Science and Engineering, Chungnam National University, 220, Gung-dong, Youseong-gu, Daejeon, 305-764 (Korea, Republic of); Kim, Hyojin [Department of Materials Science and Engineering, Chungnam National University, 220, Gung-dong, Youseong-gu, Daejeon, 305-764 (Korea, Republic of)

    2007-01-15

    Inverted hysteresis loops (IHL) of negative net area have been measured for some films using vibrating sample magnetometer (VSM), SQUID magnetometer or magneto-optic Kerr effect magnetometer. All of the IHL were observed in the field direction along the hard axis. An IHL violates the thermo-mechanical second law. This work points out that an IHL arises when |M{sub x}|-bar |M{sub z}| (M{sub x} and M{sub z}: the parallel and normal to the field direction components of magnetization vector) if the sample is set at certain inappropriate positions in VSM and SQUID magnetometer experiments, and the sense voltage is solely attributed to M{sub x} while it also relates to M{sub z}.

  6. Experimental and Numerical Study on the Semi-Closed Loop Control of a Planar Parallel Robot Manipulator

    Directory of Open Access Journals (Sweden)

    Yong-Lin Kuo

    2014-01-01

    Full Text Available This paper implements the model predictive control to fulfill the position control of a 3-DOF 3-RRR planar parallel manipulator. The research work covers experimental and numerical studies. First, an experimental hardware-in-the-loop system to control the manipulator is constructed. The manipulator is driven by three DC motors, and each motor has an encoder to measure the rotating angles of the motors. The entire system is designed as a semiclosed-loop control system. The controller receives the encoder signals as inputs to produce signals driving the motors. Secondly, the motor parameters are obtained by system identification, and the controllers are designed based on these parameters. Finally, the numerical simulations are performed by incorporating the manipulator kinematics and the motor dynamics; the results are compared with those from the experiments. Both results show that they are in good agreement at steady state. There are two main contributions in this paper. One is the application of the model predictive control to the planar parallel manipulator, and the other one is to overcome the effects of the uncertainties of the DC motors and the performance of the position control due to the dynamic behavior of the manipulator.

  7. Tasks related to increase of RA reactor exploitation and experimental potential, Independent CO2 loop for cooling the samples irradiated in RA reactor vertical experimental channels, (I-IV), part I

    International Nuclear Information System (INIS)

    Pavicevic, M.

    1963-07-01

    This volume contains the description of the design project of the head of the low-temperature coolant loops needed for cooling the samples to be irradiated in the RA vertical experimental channels. The thermal and mechanical calculations are included as well as calculation of antireactivity and activation of the construction materials. Cost estimation data are included as well. The drawings included are: head of the coolant loop; diagram of CO 2 coolant temperature dependence; diagrams of weight of the loop tubes in the channels; axial distribution of the thermal neutron flux. Engineering drawings of two design solutions of the low-temperature loops with details are part of this volume

  8. Experimental Study of Flexible Plate Vibration Control by Using Two-Loop Sliding Mode Control Strategy

    Science.gov (United States)

    Yang, Jingyu; Lin, Jiahui; Liu, Yuejun; Yang, Kang; Zhou, Lanwei; Chen, Guoping

    2017-08-01

    It is well known that intelligent control theory has been used in many research fields, novel modeling method (DROMM) is used for flexible rectangular active vibration control, and then the validity of new model is confirmed by comparing finite element model with new model. In this paper, taking advantage of the dynamics of flexible rectangular plate, a two-loop sliding mode (TSM) MIMO approach is introduced for designing multiple-input multiple-output continuous vibration control system, which can overcome uncertainties, disturbances or unstable dynamics. An illustrative example is given in order to show the feasibility of the method. Numerical simulations and experiment confirm the effectiveness of the proposed TSM MIMO controller.

  9. Air water loop - an experimental facility to study thermal hydraulics of AHWR steam drum

    International Nuclear Information System (INIS)

    Bagul, R.K.; Pilkhwal, D.S.; Jain, V.; Vijayan, P.K.

    2014-05-01

    In the proposed Indian Advanced Heavy Water Reactor (AHWR) the coolant recirculation in the primary system is achieved by two-phase natural circulation. The two-phase steam-water mixture from the reactor core is separated in steam drum by gravity. Gravity separation of phases may lead to undesirable phenomena - carryover and carryunder. Carryover is the entrainment of liquid droplets in the vapor phase.Carryover needs to be minimized to avoid erosion corrosion of turbine blades. Carryunder is the entrainment of vapor bubbles with liquid flowing back to reactor core. Significant carryunder may in turn lead to reduced flow resulting in reduced CHF margin and stability in the coolant channel. An Air-Water Loop (AWL) has been designed to carry out the experiments relevant to AHWR steam drum. The design features and scaling philosophy is described in this report. (author)

  10. Experimental investigation on start-up of mechanically pumped cooling loop

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jie [Institute of Environmental and Municipal Engineering, Qingdao Technological University, Qingdao 266033 (China)], E-mail: liu_jie@sjtu.edu.cn; Lv Mou; Zhang shuangxi [Institute of Environmental and Municipal Engineering, Qingdao Technological University, Qingdao 266033 (China); Guo Kaihua; He Zhenhui; Li Tingxuen [Center for Space Technology, Sun Yat-Sen University, Guangzhou, 510275 (China)

    2008-10-15

    The start-up of a two phase cooling system is a complex transient phenomenon especially for the mechanically pumped two phase cooling loop (MPCL) which is now a promising thermal control method for efficiently extracting heat from large electronic equipments. In this paper the system design and work principle as well as the test setup of a MPCL is presented and the start-up processes of the MPCL are studied. Experiments on the start-up processes under a variety of conditions were conducted. Special attention has been paid to the startups of the system in different evaporative temperature variable mass flow or heating load and some abnormal start-up pre-history. The transient flow exchange between the main loop and the accumulator was observed and discussed according to the different start-up patterns, which have been identified as pre-condition pump start-up and heat load start-up. During the start-up processes the system presents good stability and each part of the system performs a reasonable temperature wave except of some superheat phenomena in the evaporator. The superheat is mainly related to the evaporative temperature and the initial liquid distribution in the evaporator. In general the lower is the evaporative temperature the higher is the superheat that occurs. It also indicates that the degree of superheat is not too high when the evaporator is flooded with liquid and will not cause damage to the source equipments. In conclusion the well start-up processes in different situations may cause some liquid superheats and evaporator temperature overshoots but they will not affect much the steady state operation of the MPCL.

  11. Experimental investigation on start-up of mechanically pumped cooling loop

    Energy Technology Data Exchange (ETDEWEB)

    Jie, Liu; Mou, Lv; Shuang-xi, Zhang [Institute of Environmental and Municipal Engineering, Qingdao Technological University, Qingdao 266033 (China); Kai-hua, Guo; Zhen-hui, He; Ting-xuen, Li [Center for Space Technology, Sun Yat-Sen University, Guangzhou, 510275 (China)

    2008-10-15

    The start-up of a two phase cooling system is a complex transient phenomenon especially for the mechanically pumped two phase cooling loop (MPCL) which is now a promising thermal control method for efficiently extracting heat from large electronic equipment. In this paper the system design and work principle as well as the test setup of a MPCL is presented and the start-up processes of the MPCL are studied. Experiments on the start-up processes under a variety of conditions were conducted. Special attention has been paid to the startups of the system in different evaporative temperature variable mass flow or heating load and some abnormal start-up pre-history. The transient flow exchange between the main loop and the accumulator was observed and discussed according to the different start-up patterns, which have been identified as pre-condition pump start-up and heat load start-up. During the start-up processes the system presents good stability and each part of the system performs a reasonable temperature wave except of some superheat phenomena in the evaporator. The superheat is mainly related to the evaporative temperature and the initial liquid distribution in the evaporator. In general the lower is the evaporative temperature the higher is the superheat that occurs. It also indicates that the degree of superheat is not too high when the evaporator is flooded with liquid and will not cause damage to the source equipments. In conclusion the well start-up processes in different situations may cause some liquid superheats and evaporator temperature overshoots but they will not affect much the steady state operation of the MPCL. (author)

  12. Screening of oxygen-carrier particles based on iron-, manganese-, copper- and nickel oxides for use in chemical-looping technologies

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Marcus

    2007-07-01

    carriers were investigated in more detail in the fluidized bed, and parameters such as reaction temperature, particle size, reducing gas and experimental method were varied. With respect to reactivity with methane, the different oxygen carriers can generally be ranked in the order nickel> copper> manganese> iron whereas the crushing strength roughly follows the opposite order. Several types of inert material were used in this work, and this was found to be a very important parameter. It was found that inert material based on alumina and zirconia in general resulted in promising oxygen carriers, whereas titania, silica and magnesia were less promising with respect to reactivity or lifetime of the particles. Using a low sintering temperature in preparation is associated with a high reactivity, but also a low strength. This is because the higher temperatures provoke a breakdown of the internal porous structure which also makes them denser. Twelve out of the initial 108 particles were not useful for different reasons, including melting, lack of structure and lack of reactivity due to formation of non-reducible species. The majority of the investigated oxygen carriers are well suited for chemical-looping combustion taking into consideration the important criteria of reactivity, high conversion of the fuel, relatively high strength and ability to withstand de-fluidization, agglomeration, fragmentation and abrasion

  13. Experimental results of chemical recording using thermally sensitive liposomes

    Science.gov (United States)

    Tanner, Maria E.; Vasievich, Elizabeth A.; Protz, Jonathan M.

    2008-04-01

    A new generation of inertial measurement technology is being developed enabling a 10-micron particle to be "aware" of its geospatial location and respond to this information. The proposed approach combines an inertially-sensitive nano-structure or nano fluid/structure system with a nano-sized chemical reactor that functions as an analog computer. By using chemistry to perform the necessary computational steps in our device, it is possible to overcome traditional limitations on device size. The proposed nanodevice utilizes mechanical sensing and chemical recording to record the time history of various state variables. Using a micro-track containing regions of different temperatures and thermally-sensitive liposomes (TSL), a range of accelerations can be recorded and the position determined. Through careful design, TSL can be developed that have unique transition temperatures and each class of TSL will contain a unique DNA sequence that serves as an identifier. Acceleration can be detected through buoyancy-driven convection. As the liposomes travel to regions of warmer temperature, they will release their contents at the recording site, thus documenting the acceleration. This paper will present the initial proof-of-concept experimental results achieved from chemical recording of the state variable temperature. The experiment focuses on the liposome release of the DNA due to temperature variations and subsequent binding and recording of the time history. These results prove the feasibility of this method of sensing and recording of the history of state variables.

  14. Experimental and numerical thermohydraulic study of a supercritical helium loop in forced convection under pulsed heat loads

    International Nuclear Information System (INIS)

    Lagier, Benjamin

    2014-01-01

    Future fusion reactor devices such as ITER or JT-60SA will produce thermonuclear fusion reaction in plasmas at several millions of degrees. The confinement in the center of the chamber is achieved by very intense magnetic fields generated by superconducting magnets. These coils have to be cooled down to 4.4 K through a forced flow of supercritical helium. The cyclic behavior of the machines leads to pulsed thermal heat loads which will have to be handled by the refrigerator. The HELIOS experiment built in CEA Grenoble is a scaled down model of the helium distribution system of the tokamak JT-60SA composed of a saturated helium bath and a supercritical helium loop. The thesis work explores HELIOS capabilities for experimental and numerical investigations on three heat load smoothing strategies: the use of the saturated helium bath as an open thermal buffer, the rotation speed variation of the cold circulator and the bypassing of the heated section. The developed model describes well the physical evolutions of the helium loop (pressure, temperature, mass flow) submitted to heat loads observed during experiments. Advanced controls have been tested and validated to improve the stability of the refrigerator and to optimize the refrigeration power. (author) [fr

  15. An experimental study on the performance of closed loop pulsating heat pipe (CLPHP) with methanol as a working fluid

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Md. Lutfor; Nourin, Farah Nazifa, E-mail: farahnazifanourin@gmail.com; Salsabil, Zaimaa; Yasmin, Nusrat, E-mail: nusratyasmin015@gmail.com [Military Institute of Science and Technology, Mirpur Cantonment, Dhaka -1216 (Bangladesh); Ali, Mohammad [Bangladesh University of Engineering and Technology, Dhaka -1000 (Bangladesh)

    2016-07-12

    Thermal control is an important topic for thermal management of small electrical and electronic devices. Closed loop pulsating heat pipe (CLPHP) arises as the best solution for thermal control. The aim of this experimental study is to search a CLPHP of better thermal performance for cooling different electrical and electronic devices. In this experiment, methanol is used as working fluid. The effect of using methanol as a working fluid is studied on thermal performance in different filling ratios and angles of inclination. A copper capillary tube is used where the inner diameter is 2 mm,outer diameter is 2.5 mm and 250 mm long. The CLPHP has 8 loops where the evaporation section is 50 mm, adiabatic section is 120 mm and condensation section is 80 mm. The experiment is done using FR of 40%-70% with 10% of interval and angles of inclination 0° (vertical), 30°, 45°, 60° varying heat input. The results are compared on the basis of evaporator temperature, condenser temperature and their differences, thermal resistance, heat transfer co-efficient, power input and pulsating time. The results demonstrate the effect of methanol in different filling ratios and angles of inclination. M ethanol shows better performance at 30° inclination with 40% FR.

  16. An experimental study on the performance of closed loop pulsating heat pipe (CLPHP) with methanol as a working fluid

    Science.gov (United States)

    Rahman, Md. Lutfor; Nourin, Farah Nazifa; Salsabil, Zaimaa; Yasmin, Nusrat; Ali, Mohammad

    2016-07-01

    Thermal control is an important topic for thermal management of small electrical and electronic devices. Closed loop pulsating heat pipe (CLPHP) arises as the best solution for thermal control. The aim of this experimental study is to search a CLPHP of better thermal performance for cooling different electrical and electronic devices. In this experiment, methanol is used as working fluid. The effect of using methanol as a working fluid is studied on thermal performance in different filling ratios and angles of inclination. A copper capillary tube is used where the inner diameter is 2mm,outer diameter is 2.5mm and 250mm long. The CLPHP has 8 loops where the evaporation section is 50mm, adiabatic section is 120mm and condensation section is 80mm. The experiment is done using FR of 40%-70% with 10% of interval and angles of inclination 0° (vertical), 30°, 45°, 60° varying heat input. The results are compared on the basis of evaporator temperature, condenser temperature and their differences, thermal resistance, heat transfer co-efficient, power input and pulsating time. The results demonstrate the effect of methanol in different filling ratios and angles of inclination. M ethanol shows better performance at 30° inclination with 40% FR.

  17. An experimental study on the performance of closed loop pulsating heat pipe (CLPHP) with methanol as a working fluid

    International Nuclear Information System (INIS)

    Rahman, Md. Lutfor; Nourin, Farah Nazifa; Salsabil, Zaimaa; Yasmin, Nusrat; Ali, Mohammad

    2016-01-01

    Thermal control is an important topic for thermal management of small electrical and electronic devices. Closed loop pulsating heat pipe (CLPHP) arises as the best solution for thermal control. The aim of this experimental study is to search a CLPHP of better thermal performance for cooling different electrical and electronic devices. In this experiment, methanol is used as working fluid. The effect of using methanol as a working fluid is studied on thermal performance in different filling ratios and angles of inclination. A copper capillary tube is used where the inner diameter is 2 mm,outer diameter is 2.5 mm and 250 mm long. The CLPHP has 8 loops where the evaporation section is 50 mm, adiabatic section is 120 mm and condensation section is 80 mm. The experiment is done using FR of 40%-70% with 10% of interval and angles of inclination 0° (vertical), 30°, 45°, 60° varying heat input. The results are compared on the basis of evaporator temperature, condenser temperature and their differences, thermal resistance, heat transfer co-efficient, power input and pulsating time. The results demonstrate the effect of methanol in different filling ratios and angles of inclination. M ethanol shows better performance at 30° inclination with 40% FR.

  18. Operation of the NETL Chemical Looping Reactor with Natural Gas and a Novel Copper-Iron Material

    Energy Technology Data Exchange (ETDEWEB)

    Bayham, Sanuel [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Straub, Doug [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Weber, Justin [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2017-02-01

    As part of the U.S. Department of Energy’s Advanced Combustion Program, the National Energy Technology Laboratory’s Research and Innovation Center (NETL R&IC) is investigating the feasibility of a novel combustion concept in which the GHG emissions can be significantly reduced. This concept involves burning fuel and air without mixing these two reactants. If this concept is technically feasible, then CO2 emissions can be significantly reduced at a much lower cost than more conventional approaches. This indirect combustion concept has been called Chemical Looping Combustion (CLC) because an intermediate material (i.e., a metaloxide) is continuously cycled to oxidize the fuel. This CLC concept is the focus of this research and will be described in more detail in the following sections.

  19. Chemical looping fluidized-bed concentrating solar power system and method

    Science.gov (United States)

    Ma, Zhiwen

    2017-07-11

    A concentrated solar power (CSP) plant comprises a receiver configured to contain a chemical substance for a chemical reaction and an array of heliostats. Each heliostat is configured to direct sunlight toward the receiver. The receiver is configured to transfer thermal energy from the sunlight to the chemical substance in a reduction reaction. The CSP plant further comprises a first storage container configured to store solid state particles produced by the reduction reaction and a heat exchanger configured to combine the solid state particles and gas through an oxidation reaction. The heat exchanger is configured to transfer heat produced in the oxidation reaction to a working fluid to heat the working fluid. The CSP plant further comprises a power turbine coupled to the heat exchanger, such that the heated working fluid turns the power turbine, and a generator coupled to and driven by the power turbine to generate electricity.

  20. Exergy Analysis of a Syngas-Fueled Combined Cycle with Chemical-Looping Combustion and CO2 Sequestration

    Directory of Open Access Journals (Sweden)

    Álvaro Urdiales Montesino

    2016-08-01

    Full Text Available Fossil fuels are still widely used for power generation. Nevertheless, it is possible to attain a short- and medium-term substantial reduction of greenhouse gas emissions to the atmosphere through a sequestration of the CO2 produced in fuels’ oxidation. The chemical-looping combustion (CLC technique is based on a chemical intermediate agent, which gets oxidized in an air reactor and is then conducted to a separated fuel reactor, where it oxidizes the fuel in turn. Thus, the oxidation products CO2 and H2O are obtained in an output flow in which the only non-condensable gas is CO2, allowing the subsequent sequestration of CO2 without an energy penalty. Furthermore, with shrewd configurations, a lower exergy destruction in the combustion chemical transformation can be achieved. This paper focus on a second law analysis of a CLC combined cycle power plant with CO2 sequestration using syngas from coal and biomass gasification as fuel. The key thermodynamic parameters are optimized via the exergy method. The proposed power plant configuration is compared with a similar gas turbine system with a conventional combustion, finding a notable increase of the power plant efficiency. Furthermore, the influence of syngas composition on the results is investigated by considering different H2-content fuels.

  1. Thermal and mechanical behaviour of oxygen carrier materials for chemical looping combustion in a packed bed reactor

    International Nuclear Information System (INIS)

    Jacobs, M.; Van Noyen, J.; Larring, Y.; Mccann, M.; Pishahang, M.; Amini, S.; Ortiz, M.; Galluci, F.; Sint-Annaland, M.V.; Tournigant, D.; Louradour, E.; Snijkers, F.

    2015-01-01

    Highlights: • Ilmenite-based oxygen carriers were developed for packed-bed chemical looping. • Addition of Mn 2 O 3 increased mechanical strength and microstructure of the carriers. • Oxygen carriers were able to withstand creep and thermal cycling up to 1200 °C. • Ilmenite-based granules are a promising shape for packed-bed reactor conditions. - Abstract: Chemical looping combustion (CLC) is a promising carbon capture technology where cyclic reduction and oxidation of a metallic oxide, which acts as a solid oxygen carrier, takes place. With this system, direct contact between air and fuel can be avoided, and so, a concentrated CO 2 stream is generated after condensation of the water in the exit gas stream. An interesting reactor system for CLC is a packed bed reactor as it can have a higher efficiency compared to a fluidized bed concept, but it requires other types of oxygen carrier particles. The particles must be larger to avoid a large pressure drop in the reactor and they must be mechanically strong to withstand the severe reactor conditions. Therefore, oxygen carriers in the shape of granules and based on the mineral ilmenite were subjected to thermal cycling and creep tests. The mechanical strength of the granules before and after testing was investigated by crush tests. In addition, the microstructure of these oxygen particles was studied to understand the relationship between the physical properties and the mechanical performance. It was found that the granules are a promising shape for a packed bed reactor as no severe degradation in strength was noticed upon thermal cycling and creep testing. Especially, the addition of Mn 2 O 3 to the ilmenite, which leads to the formation of an iron–manganese oxide, seems to results in stronger granules than the other ilmenite-based granules.

  2. Chemical decontamination for decommissioning purposes. (Vigorous decontamination tests of steel samples in a special test loop)

    International Nuclear Information System (INIS)

    Bregani, F.; Pascali, R.; Rizzi, R.

    1984-01-01

    The aim of the research activities described was to develop vigorous decontamination techniques for decommissioning purposes, taking into account the cost of treatment of the radwaste, to achieve possibly unrestricted release of the treated components, and to obtain know-how for in situ hard decontamination. The decontamination procedures for strong decontamination have been optimized in static and dynamic tests (DECO-loop). The best values have been found for: (i) hydrochloric acid: 4 to 5% vol. at low temperature, 0.7 to 1% vol. at high temperature (80 0 C); (ii) hydrofluoric plus nitric acid: 1.5% vol. HF + 5% vol. HNO 3 at low temperature; 0.3 to 0.5% vol. HF + 2.5 to 5% vol. HNO 3 at high temperature. High flow rates are not necessary, but a good re-circulation of the solution is needed. The final contamination levels, after total oxide removal, are in accordance with limits indicated for unrestricted release of materials in some countries. The arising of the secondary waste is estimated. Decontamination of a 10 m 2 surface would typically produce 0.5 to 3.0 kg of dry waste, corresponding to 1.6 to 10 kg of concrete conditioned waste

  3. Closed-loop control of laser assisted chemical vapor deposition growth of carbon nanotubes

    NARCIS (Netherlands)

    Burgt, Y. van de; Bellouard, Y.; Mandamparambil, R.; Haluska, M.; Dietzel, A.H.

    2012-01-01

    Laser-assisted chemical vapor deposition growth is an attractive mask-less process for growing locally aligned nanotubes in selected places on temperature sensitive substrates. An essential parameter for a successful and reproducible synthesis of nanotubes is the temperature during growth. Here, we

  4. Coal Direct Chemical Looping Retrofit to Pulverized Coal Power Plants for In-Situ CO2 Capture

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Liang; Li, Fanxing; Kim, Ray; Bayham, Samuel; McGiveron, Omar; Tong, Andrew; Connell, Daniel; Luo, Siwei; Sridhar, Deepak; Wang, Fei; Sun, Zhenchao; Fan, Liang-Shih

    2013-09-30

    A novel Coal Direct Chemical Looping (CDCL) system is proposed to effectively capture CO2 from existing PC power plants. The work during the past three years has led to an oxygen carrier particle with satisfactory performance. Moreover, successful laboratory, bench scale, and integrated demonstrations have been performed. The proposed project further advanced the novel CDCL technology to sub-pilot scale (25 kWth). To be more specific, the following objectives attained in the proposed project are: 1. to further improve the oxygen carrying capacity as well as the sulfur/ash tolerance of the current (working) particle; 2. to demonstrate continuous CDCL operations in an integrated mode with > 99% coal (bituminous, subbituminous, and lignite) conversion as well as the production of high temperature exhaust gas stream that is suitable for steam generation in existing PC boilers; 3. to identify, via demonstrations, the fate of sulfur and NOx; 4. to conduct thorough techno-economic analysis that validates the technical and economical attractiveness of the CDCL system. The objectives outlined above were achieved through collaborative efforts among all the participants. CONSOL Energy Inc. performed the techno-economic analysis of the CDCL process. Shell/CRI was able to perform feasibility and economic studies on the large scale particle synthesis and provide composite particles for the sub-pilot scale testing. The experience of B&W (with boilers) and Air Products (with handling gases) assisted the retrofit system design as well as the demonstration unit operations. The experience gained from the sub-pilot scale demonstration of the Syngas Chemical Looping (SCL) process at OSU was able to ensure the successful handling of the solids. Phase 1 focused on studies to improve the current particle to better suit the CDCL operations. The optimum operating conditions for the reducer reactor such as the temperature, char gasification enhancer type, and flow rate were identified. The

  5. Aviation Human-in-the-Loop Simulation Studies: Experimental Planning, Design, and Data Management

    Science.gov (United States)

    2014-01-01

    experimental legs, we drafted a more global-scale weather picture of the east coast that would support those local weather observations. We crafted frontal...sisting with data collection were provided a weather briefing packet that contained not only current automated observations, but also synoptic ...descriptions, satellite pictures (captured on a real day when conditions matched our virtual environment), airmen meteorological information (AIRMETS

  6. Development of a thermal-hydraulic code for reflood analysis in a PWR experimental loop

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Sabrina P.; Mesquita, Amir Z.; Rezende, Hugo C., E-mail: sabrinapral@gmail.com, E-mail: amir@cdtn.brm, E-mail: hcr@cdtn.br, E-mail: hcr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Palma, Daniel A.P., E-mail: dapalma@cnen.gov.br [Comissão Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2017-07-01

    A process of fundamental importance in the event of Loss of Coolant Accident (LOCA) in Pressurized Water nuclear Reactors (PWR) is the reflood of the core or rewetting of nuclear fuels. The Nuclear Technology Development Center (CDTN) has been developing since the 70’s programs to allow Brazil to become independent in the field of reactor safety analysis. To that end, in the 80’s was designed, assembled and commissioned one Rewetting Test Facility (ITR in Portuguese). This facility aims to investigate the phenomena involved in the thermal hydraulic reflood phase of a Loss of Coolant Accident in a PWR nuclear reactor. This work aim is the analysis of physical and mathematical models governing the rewetting phenomenon, and the development a thermo-hydraulic simulation code of a representative experimental circuit of the PWR reactors core cooling channels. It was possible to elaborate and develop a code called REWET. The results obtained with REWET were compared with the experimental results of the ITR, and with the results of the Hydroflut code, that was the old program previously used. An analysis was made of the evolution of the wall temperature of the test section as well as the evolution of the front for two typical tests using the two codes calculation, and experimental results. The result simulated by REWET code for the rewetting time also came closer to the experimental results more than those calculated by Hydroflut code. (author)

  7. Development of a thermal-hydraulic code for reflood analysis in a PWR experimental loop

    International Nuclear Information System (INIS)

    Alves, Sabrina P.; Mesquita, Amir Z.; Rezende, Hugo C.; Palma, Daniel A.P.

    2017-01-01

    A process of fundamental importance in the event of Loss of Coolant Accident (LOCA) in Pressurized Water nuclear Reactors (PWR) is the reflood of the core or rewetting of nuclear fuels. The Nuclear Technology Development Center (CDTN) has been developing since the 70’s programs to allow Brazil to become independent in the field of reactor safety analysis. To that end, in the 80’s was designed, assembled and commissioned one Rewetting Test Facility (ITR in Portuguese). This facility aims to investigate the phenomena involved in the thermal hydraulic reflood phase of a Loss of Coolant Accident in a PWR nuclear reactor. This work aim is the analysis of physical and mathematical models governing the rewetting phenomenon, and the development a thermo-hydraulic simulation code of a representative experimental circuit of the PWR reactors core cooling channels. It was possible to elaborate and develop a code called REWET. The results obtained with REWET were compared with the experimental results of the ITR, and with the results of the Hydroflut code, that was the old program previously used. An analysis was made of the evolution of the wall temperature of the test section as well as the evolution of the front for two typical tests using the two codes calculation, and experimental results. The result simulated by REWET code for the rewetting time also came closer to the experimental results more than those calculated by Hydroflut code. (author)

  8. Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

    KAUST Repository

    Zhao, Zhenlong

    2013-01-17

    Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two-part series, a new rotary reactor concept for gas-fueled CLC is proposed and analyzed. In part 1, the detailed configuration of the rotary reactor is described. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet and exit. Two purging sectors are used to avoid the mixing between the fuel stream and the air stream. The rotary wheel consists of a large number of channels with copper oxide coated on the inner surface of the channels. The support material is boron nitride, which has high specific heat and thermal conductivity. Gas flows through the reactor at elevated pressure, and it is heated to a high temperature by fuel combustion. Typical design parameters for a thermal capacity of 1 MW have been proposed, and a simplified model is developed to predict the performances of the reactor. The potential drawbacks of the rotary reactor are also discussed. © 2012 American Chemical Society.

  9. Screening of NiFe2O4 Nanoparticles as Oxygen Carrier in Chemical Looping Hydrogen Production

    DEFF Research Database (Denmark)

    Liu, Shuai; He, Fang; Huang, Zhen

    2016-01-01

    The objective of this paper is to systematically investigate the influences of different preparation methods on the properties of NiFe2O4 nanoparticles as oxygen carrier in chemical looping hydrogen production (CLH). The solid state (SS), coprecipitation (CP), hydrothermal (HT), and sol-gel (SG) ...... analyses....

  10. Experimental Study of Single Phase Flow in a Closed-Loop Cooling System with Integrated Mini-Channel Heat Sink

    Directory of Open Access Journals (Sweden)

    Lei Ma

    2016-06-01

    Full Text Available The flow and heat transfer characteristics of a closed-loop cooling system with a mini-channel heat sink for thermal management of electronics is studied experimentally. The heat sink is designed with corrugated fins to improve its heat dissipation capability. The experiments are performed using variable coolant volumetric flow rates and input heating powers. The experimental results show a high and reliable thermal performance using the heat sink with corrugated fins. The heat transfer capability is improved up to 30 W/cm2 when the base temperature is kept at a stable and acceptable level. Besides the heat transfer capability enhancement, the capability of the system to transfer heat for a long distance is also studied and a fast thermal response time to reach steady state is observed once the input heating power or the volume flow rate are varied. Under different input heat source powers and volumetric flow rates, our results suggest potential applications of the designed mini-channel heat sink in cooling microelectronics.

  11. Loop-to-loop coupling.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Lucero, Larry Martin; Langston, William L.; Salazar, Robert Austin; Coleman, Phillip Dale; Basilio, Lorena I.; Bacon, Larry Donald

    2012-05-01

    This report estimates inductively-coupled energy to a low-impedance load in a loop-to-loop arrangement. Both analytical models and full-wave numerical simulations are used and the resulting fields, coupled powers and energies are compared. The energies are simply estimated from the coupled powers through approximations to the energy theorem. The transmitter loop is taken to be either a circular geometry or a rectangular-loop (stripline-type) geometry that was used in an experimental setup. Simple magnetic field models are constructed and used to estimate the mutual inductance to the receiving loop, which is taken to be circular with one or several turns. Circuit elements are estimated and used to determine the coupled current and power (an equivalent antenna picture is also given). These results are compared to an electromagnetic simulation of the transmitter geometry. Simple approximate relations are also given to estimate coupled energy from the power. The effect of additional loads in the form of attached leads, forming transmission lines, are considered. The results are summarized in a set of susceptibility-type curves. Finally, we also consider drives to the cables themselves and the resulting common-to-differential mode currents in the load.

  12. Actions needed for RA reactor exploitation - I-IV, Part II, Design project VI-SA 1, Experimental loop for testing the EL-4 reactor fuel elements in the central vertical experimental channel of the RA reactor in Vinca

    International Nuclear Information System (INIS)

    Novakovic, M.

    1961-12-01

    The objective of installing the VISA-1 loop was testing the fuel elements of the EL-4 reactor. The fuel elements planned for testing are natural UO 2 with beryllium cladding, cooled by CO 2 under nominal pressure of 60 at and temperature 600 deg C. central vertical experimental channel of the RA reactor was chosen for installing a test loop cooled by CO 2 . This report contains the detailed design project of the testing loop with the control system and safety analysis of the planned experiment

  13. Finial Scientific/Technical Report: Application of a Circulating Fluidized Bed Process for the Chemical Looping Combustion of Solid Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Wei-Ping Pan; Dr. John T. Riley

    2005-10-10

    Chemical Looping Combustion is a novel combustion technology for the inherent separation of the greenhouse gas, CO{sub 2}. In 1983, Richter and Knoche proposed reversible combustion, which utilized both the oxidation and reduction of metal. Metal associated with its oxidized form as an oxygen carrier was circulated between two reactors--oxidizer and reducer. In the reducer, the solid oxygen carrier reacts with the fuel to produce CO{sub 2}, H{sub 2}O and elemental metal only. Pure CO{sub 2} will be obtained in the exit gas stream from the reducer after H{sub 2}O is condensed. The pure CO{sub 2} is ready for subsequent sequestration. In the oxidizer, the elemental metal reacts with air to form metal oxide and separate oxygen from nitrogen. Only nitrogen and some unused oxygen are emitted from the oxidizer. The advantage of CLC compared to normal combustion is that CO{sub 2} is not diluted with nitrogen but obtained in a relatively pure form without any energy needed for separation. In addition to the energy-free purification of CO{sub 2}, the CLC process also provides two other benefits. First, NO{sub x} formation can be largely eliminated. Secondly, the thermal efficiency of a CLC system is very high. Presently, the CLC process has only been used with natural gas. An oxygen carrier based on an energy balance analysis and thermodynamics analysis was selected. Copper (Cu) seems to be the best choice for the CLC system for solid fuels. From this project, the mechanisms of CuO reduction by solid fuels may be as follows: (1) If pyrolysis products of solid fuels are available, reduction of CuO could start at about 400 C or less. (2) If pyrolysis products of solid fuels are unavailable and the reduction temperature is lower, reduction of CuO could occur at an onset temperature of about 500 C, char gasification reactivity in CO{sub 2} was lower at lower temperatures. (3) If pyrolysis products of solid fuels are unavailable and the reduction temperature is higher than 750 C

  14. Alstom's Chemical Looping Combustion Prototype for CO2 Capture from Existing Pulverized Coal-Fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Andrus, Jr., Herbert E. [Alstom Power Inc., Windsor, CT (United States); Chiu, John H. [Alstom Power Inc., Windsor, CT (United States); Edberg, Carl D. [Alstom Power Inc., Windsor, CT (United States); Thibeault, Paul R. [Alstom Power Inc., Windsor, CT (United States); Turek, David G. [Alstom Power Inc., Windsor, CT (United States)

    2012-09-30

    Alstom’s Limestone Chemical Looping (LCL™) process has the potential to capture CO2 from new and existing coal-fired power plants while maintaining high plant power generation efficiency. This new power plant concept is based on a hybrid combustion- gasification process utilizing high temperature chemical and thermal looping technology. This process could also be potentially configured as a hybrid combustion-gasification process producing a syngas or hydrogen for various applications while also producing a separate stream of CO2 for use or sequestration. The targets set for this technology is to capture over 90% of the total carbon in the coal at cost of electricity which is less than 20% greater than Conventional PC or CFB units. Previous work with bench scale test and a 65 kWt Process Development Unit Development (PDU) has validated the chemistry required for the chemical looping process and provided for the investigation of the solids transport mechanisms and design requirements. The objective of this project is to continue development of the combustion option of chemical looping (LCL-C™) by designing, building and testing a 3 MWt prototype facility. The prototype includes all of the equipment that is required to operate the chemical looping plant in a fully integrated manner with all major systems in service. Data from the design, construction, and testing will be used to characterize environmental performance, identify and address technical risks, reassess commercial plant economics, and develop design information for a demonstration plant planned to follow the proposed Prototype. A cold flow model of the prototype will be used to predict operating conditions for the prototype and help in operator training. Operation of the prototype will provide operator experience with this new technology and performance data of the LCL-C™ process, which will be applied to the commercial design and economics and plan for a future demonstration

  15. Results of water chemistry control in the in-pile ''Callisto'' loop (an experimental PWR rig installed in the BR2 reactor)

    International Nuclear Information System (INIS)

    Weber, M.; Benoit, P.; Dekeyser, J.; Verwimp, A.

    1994-01-01

    Since June 1992, a new experimental facility, called CALLISTO, is being irradiated in the BR2 materials testing reactor at Mol, Belgium. The main objective of the present test campaign is to study the behaviour of advanced fuel to high burn-up rates in a realistic PWR environment. Three in-pile sections, containing each 9 fuel rods, are loaded inside the reactor vessel and are connected to a common out-of-pile pressurized water circulation loop (ref.1). The later is branched-off into a purification circuit (feed-bleed concept) and further equipped with safety and auxiliary systems. To cope with the test programme, the equipments are designed so that the guidelines of a PWR primary water chemistry can be followed (ref.2). Real steady-state conditions cannot be observed because the typical BR2 cycle (3 weeks running/3 weeks shut-down) is much shorter and because the rig is cooled down during each reactor shut-down. The purpose of this poster is to provide results of chemical parameters recorded during the cycling behaviour of the CALLISTO primary water. (authors). 4 figs., 1 tab., 2 refs

  16. Operation of the NETL Chemical Looping Reactor with Natural Gas and a Novel Copper-Iron Material

    Energy Technology Data Exchange (ETDEWEB)

    Straub, Douglas [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Bayham, Samuel [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Weber, Justin [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2017-02-21

    The proposed Clean Power Plan requires CO2 emission reductions of 30% by 2030 and further reductions are targeted by 2050. The current strategies to achieve the 30% reduction targets do not include options for coal. However, the 2016 Annual Energy Outlook suggests that coal will continue to provide more electricity than renewable sources for many regions of the country in 2035. Therefore, cost effective options to reduce greenhouse gas emissions from fossil fuel power plants are vital in order to achieve greenhouse gas reduction targets beyond 2030. As part of the U.S. Department of Energy’s Advanced Combustion Program, the National Energy Technology Laboratory’s Research and Innovation Center (NETL R&IC) is investigating the feasibility of a novel combustion concept in which the GHG emissions can be significantly reduced. This concept involves burning fuel and air without mixing these two reactants. If this concept is technically feasible, then CO2 emissions can be significantly reduced at a much lower cost than more conventional approaches. This indirect combustion concept has been called Chemical Looping Combustion (CLC) because an intermediate material (i.e., a metal-oxide) is continuously cycled to oxidize the fuel. This CLC concept is the focus of this research and will be described in more detail in the following sections. The solid material that is used to transport oxygen is called an oxygen carrier material. The cost, durability, and performance of this material is a key issue for the CLC technology. Researchers at the NETL R&IC have developed an oxygen carrier material that consists of copper, iron, and alumina. This material has been tested extensively using lab scale instruments such as thermogravimetric analysis (TGA), scanning electron microscopy (SEM), mechanical attrition (ASTM D5757), and small fluidized bed reactor tests. This report will describe the results from a realistic, circulating, proof-of-concept test that was

  17. Hydrogen Production from Cyclic Chemical Looping Steam Methane Reforming over Yttrium Promoted Ni/SBA-16 Oxygen Carrier

    Directory of Open Access Journals (Sweden)

    Sanaz Daneshmand-Jahromi

    2017-09-01

    Full Text Available In this work, the modification of Ni/SBA-16 oxygen carrier (OC with yttrium promoter is investigated. The yttrium promoted Ni-based oxygen carrier was synthesized via co-impregnation method and applied in chemical looping steam methane reforming (CL-SMR process, which is used for the production of clean energy carrier. The reaction temperature (500–750 °C, Y loading (2.5–7.4 wt. %, steam/carbon molar ratio (1–5, Ni loading (10–30 wt. % and life time of OCs over 16 cycles at 650 °C were studied to investigate and optimize the structure of OC and process temperature with maximizing average methane conversion and hydrogen production yield. The synthesized OCs were characterized by multiples techniques. The results of X-ray powder diffraction (XRD and energy dispersive X-ray spectroscopy (EDX of reacted OCs showed that the presence of Y particles on the surface of OCs reduces the coke formation. The smaller NiO species were found for the yttrium promoted OC and therefore the distribution of Ni particles was improved. The reduction-oxidation (redox results revealed that 25Ni-2.5Y/SBA-16 OC has the highest catalytic activity of about 99.83% average CH4 conversion and 85.34% H2 production yield at reduction temperature of 650 °C with the steam to carbon molar ratio of 2.

  18. Analysis of Combined Cycle Power Plants with Chemical Looping Reforming of Natural Gas and Pre-Combustion CO2 Capture

    Directory of Open Access Journals (Sweden)

    Shareq Mohd Nazir

    2018-01-01

    Full Text Available In this paper, a gas-fired combined cycle power plant subjected to a pre-combustion CO2 capture method has been analysed under different design conditions and different heat integration options. The power plant configuration includes the chemical looping reforming (CLR of natural gas (NG, water gas shift (WGS process, CO2 capture and compression, and a hydrogen fuelled combined cycle to produce power. The process is denoted as a CLR-CC process. One of the main parameters that affects the performance of the process is the pressure for the CLR. The process is analysed at different design pressures for the CLR, i.e., 5, 10, 15, 18, 25 and 30 bar. It is observed that the net electrical efficiency increases with an increase in the design pressure in the CLR. Secondly, the type of steam generated from the cooling of process streams also effects the net electrical efficiency of the process. Out of the five different cases including the base case presented in this study, it is observed that the net electrical efficiency of CLR-CCs can be improved to 46.5% (lower heating value of NG basis by producing high-pressure steam through heat recovery from the pre-combustion process streams and sending it to the Heat Recovery Steam Generator in the power plant.

  19. Thermogravimetric Analysis of Modified Hematite by Methane (CH{sub 4}) for Chemical-Looping Combustion: A Global Kinetics Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Miller, Duane D

    2013-10-01

    Iron oxide (Fe{sub 2}O{sub 3}) or in its natural form (hematite) is a potential material to capture CO{sub 2} through the chemical-looping combustion (CLC) process. It is known that magnesium (Mg) is an effective methyl cleaving catalyst and as such it has been combined with hematite to assess any possible enhancement to the kinetic rate for the reduction of Fe{sub 2}O{sub 3} with methane. Therefore, in order to evaluate its effectiveness as a hematite additive, the behaviors of Mg-modified hematite samples (hematite –5% Mg(OH){sub 2}) have been analyzed with regard to assessing any enhancement to the kinetic rate process. The Mg-modified hematite was prepared by hydrothermal synthesis. The reactivity experiments were conducted in a thermogravimetric analyzer (TGA) using continuous stream of CH{sub 4} (5, 10, and 20%) at temperatures ranging from 700 to 825 {degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2}, H{sub 2}O, H{sub 2} and CO in the gaseous product. The kinetic data at reduction step obtained by isothermal experiments could be well fitted by two parallel rate equations. The modified hematite samples showed higher reactivity as compared to unmodified hematite samples during reduction at all investigated temperatures.

  20. Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 2: Base Case and Sensitivity Analysis

    KAUST Repository

    Zhao, Zhenlong

    2013-01-17

    Part 1 (10.1021/ef3014103) of this series describes a new rotary reactor for gas-fueled chemical-looping combustion (CLC), in which, a solid wheel with microchannels rotates between the reducing and oxidizing streams. The oxygen carrier (OC) coated on the surfaces of the channels periodically adsorbs oxygen from air and releases it to oxidize the fuel. A one-dimensional model is also developed in part 1 (10.1021/ef3014103). This paper presents the simulation results based on the base-case design parameters. The results indicate that both the fuel conversion efficiency and the carbon separation efficiency are close to unity. Because of the relatively low reduction rate of copper oxide, fuel conversion occurs gradually from the inlet to the exit. A total of 99.9% of the fuel is converted within 75% of the channel, leading to 25% redundant length near the exit, to ensure robustness. In the air sector, the OC is rapidly regenerated while consuming a large amount of oxygen from air. Velocity fluctuations are observed during the transition between sectors because of the complete reactions of OCs. The gas temperature increases monotonically from 823 to 1315 K, which is mainly determined by the solid temperature, whose variations with time are limited within 20 K. The overall energy in the solid phase is balanced between the reaction heat release, conduction, and convective cooling. In the sensitivity analysis, important input parameters are identified and varied around their base-case values. The resulting changes in the model-predicted performance revealed that the most important parameters are the reduction kinetics, the operating pressure, and the feed stream temperatures. © 2012 American Chemical Society.

  1. Effects of Steam and CO2 in the Fluidizing Gas when Using Bituminous Coal in Chemical-Looping Combustion

    Science.gov (United States)

    Leion, H.; Lyngfelt, A.; Mattisson, T.

    Chemical-looping combustion (CLC) is a combustion technology where an oxygen carrier is used to transfer oxygen from the combustion air to the fuel in order to avoid direct contact between air and fuel. Thus, the CO2 is inherently separated from the flue gases with a potential for considerably lower energy penalty and cost compared to other techniques for CO2 separation. The oxygen carrier is circulated between two reactors, a fuel and an air reactor, where the flue gas from the air reactor contains oxygen depleted air and the flue gas from the fuel reactor contains mainly CO2 and H2O. The water can easily be condensed and the remaining CO2 can be transported for underground storage. Most of the prior work with CLC has focused on using natural gas and syngas as fuel and oxygen carrying material normally produced from pure chemicals. However, recent work on adapting the CLC process for solid fuels with ores and natural minerals as oxygen carrier shows promising results. This paper will present results from reactivity investigations in a laboratory fluidized-bed reactor system using previously investigated natural mineral ilmenite as oxygen carrier and a bituminous Colombian coal as fuel. Experiments were conducted at a temperature of 970°C with N2, steam, and/or CO2 in the fluidizing gas. Synergy effects between steam and CO2 on fuel conversion was noted. The results show that the fuel conversion was a roughly a factor 5 faster with steam as compared to CO2 in the fluidizing gas.

  2. Loop facility for LM-MHD study

    International Nuclear Information System (INIS)

    Pan Chuanjie; Xu Zengyu; Zhao Li; Zhang Xiujie

    2007-01-01

    A loop facility, namely, New Liquid Metal Experimental Loop (NLMEL), was built in 2007 in SWIP, Which can be used to carry out the experimental investigation on the liquid metal (LM) MHD effects, such as MHD effects of liquid divertor and liquid blanket. The working fluid in the loop is Ga 68 In 20 Sn 12 alloy, which the melting point is 10.7 degree C, the density 6363 kg/m 3 , the electrical resistivity 3.3074 x 10 6 Ω·m -1 , the surface tension 0.353 N·m -1 , the dynamical viscosity 4.0 x 10 -7 m 2 /s at 20 degree C, and its chemical properties is not active. The loop facility consists of two three-phase alternating current(AC) electromagnetic (EM) pumps, dump tank, pump tank, expansion tank, calibrated flowmeter tank, EM flowmeter, electromagnet, MHD test section and its auxiliary system. Two experimental loops, namely, free surface jet flow and duct flow, were designed and installed at the experimental region of the uniform magnetic field in loop facility. The MHD experiment of liquid divertor can be carried out in free surface jet flow loop, and the MHD experimental for liquid blanket, such as MHD effect experiment in rectangular duct with FCI, can be carried out in duct flow loop. The rated voltage of two EM pumps is 380 V, the work temperature less than 500 degree C, electric current 14 and 6 A, fluid flux 11 and 4.7 m 3 /h, outlet pressure less than 6 x 10 5 and 5 x 10 5 Pa, respectively. A 12-ton electromagnet can provide the transverse magnetic field from 0 to 2.0 Tesla, and the uniform magnetic field space of 700 x 140 x 80. Total resistance of electromagnet coils is 1.5 Ω at 20 degree C. High-quality Direct Current (DC) Power supply can provide 0-200 A DC, and 0-60 kW power, the stability of current less than 1%, AC ripple factor less than 1%. Auxiliary systems include: oil cooling loop for cooling electromagnet and two EM pumps, and high purity argon device for protect gas of loop, and pumping vacuum device for loop devices, and electric device

  3. Experimental study on the supercritical startup and heat transport capability of a neon-charged cryogenic loop heat pipe

    International Nuclear Information System (INIS)

    Guo, Yuandong; Lin, Guiping; He, Jiang; Bai, Lizhan; Zhang, Hongxing; Miao, Jianyin

    2017-01-01

    Highlights: • A neon-charged CLHP integrated with a G-M cryocooler was designed and investigated. • The CLHP can realize the supercritical startup with an auxiliary heat load of 1.5 W. • Maximum heat transport capability of the CLHP was 4.5 W over a distance of 0.6 m. • There existed an optimum auxiliary heat load to expedite the supercritical startup. • There existed an optimum charged pressure to reach the largest heat transfer limit. - Abstract: Neon-charged cryogenic loop heat pipe (CLHP) can realize efficient cryogenic heat transport in the temperature range of 30–40 K, and promises great application potential in the thermal control of future space infrared exploration system. In this work, extensive experimental studies on the supercritical startup and heat transport capability of a neon-charged CLHP integrated with a G-M cryocooler were carried out, where the effects of the auxiliary heat load applied to the secondary evaporator and charged pressure of the working fluid were investigated. Experimental results showed that the CLHP could successfully realize the supercritical startup with an auxiliary heat load of 1.5 W, and there existed an optimum auxiliary heat load and charged pressure of the working fluid respectively, to achieve the maximum temperature drop rate of the primary evaporator during the supercritical startup. The CLHP could reach a maximum heat transport capability of 4.5 W over a distance of 0.6 m corresponding to the optimum charged pressure of the working fluid; however, the heat transport capability decreased with the increase of the auxiliary heat load. Furthermore, the inherent mechanisms responsible for the phenomena observed in the experiments were analyzed and discussed, to provide a better understanding from the theoretical view.

  4. Experimental tests a technological demonstrator of extraction of tritium for Pb loop systems (15.7) Li of the TBM of ITER by permeation against vacuum

    International Nuclear Information System (INIS)

    Sacritan, R.; Bonjoch, I.; Veredas, G.; Ibarra, A.

    2013-01-01

    Shortages and wasteful production of tritium, one of the necessary fuel in nuclear fusion, is putting into question the self-sufficiency of this type of energy. For this reason, the rapid recovery of tritium is a key milestone in the field of r and d for the development of efficient technologies that are able to recover the tritium generated in the loops of liquid metal reactors such as ITER fusion for reuse as fuel, thus increasing its efficiency. Once designed and manufactured a demonstrator based on a loop of liquid Pb-Li on a small scale, and equipped with high flexibility to modify process variables, the objective of this study is the realization of many experimental trials that allow quantifying the efficiency in the recovery of H 2 of loop under different conditions through the permeation against vacuum, and thus to assess the possible application for the extraction of tritium in future fusion reactors.

  5. Power process with separation of CO{sub 2} through combustion in two stages - chemical looping combustion. Final report; Kraftprocess med avskiljning av CO{sub 2} genom foerbraenning i ett tvaastegsfoerfarande - chemical looping combustion. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    Lyngfelt, Anders; Cho, Paul; Steenari, Britt-Marie; Langer, Vratislav; Eriksson, Sten; Mattisson, Tobias [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Energy Technology

    2005-06-15

    For combustion with CO{sub 2} capture, chemical-looping combustion (CLC) with inherent separation of CO{sub 2} is a promising technology. Two interconnected fluidized beds are used as reactors. In the fuel reactor, a gaseous fuel is oxidized by an oxygen carrier, e.g. metal oxide particles, producing carbon dioxide and water. The reduced oxygen carrier is then transported to the air reactor, where it is oxidized by air back to its original form before it is returned to the fuel reactor. The feasibility of using both natural iron ore and synthetic oxygen carriers based on oxides of iron, nickel, copper and manganese was determined. Oxygen carrier particles were produced by freeze granulation. To be able to study and compare the different types of oxygen carrier particles, a procedure for testing and evaluation was developed. The reactivity was evaluated in both fixed and fluidized bed laboratory reactors, simulating a CLC system by exposing the sample to alternating reducing and oxidizing conditions. In addition, the particles were characterized with respect to crushing strength, agglomeration, tendency for carbon deposition as well as chemical and physical parameters. The rates of reaction varied and were highly dependent upon the oxygen carrier used. For the natural iron ore it was found that a high yield of CH{sub 4} to CO{sub 2} was possible although the solid reactivity was relatively low. The reactivity of the freeze granulated particles were considerably higher, with the oxygen carriers based on nickel and copper having the highest reactivity in comparison to Fe and Mn based particles. However all of the investigated samples had a reactivity sufficient for use in a CLC of interconnected fluidized beds. The copper oxide particles agglomerated and may not be suitable as an oxygen carrier. Carbon formation and agglomeration was studied in detail, and the results suggest that neither of those should be a problem in this process, except for copper which

  6. Viability of fuel switching of a gas-fired power plant operating in chemical looping combustion mode

    International Nuclear Information System (INIS)

    Basavaraja, R.J.; Jayanti, S.

    2015-01-01

    CLC (chemical looping combustion) promises to be a more efficient way of CO 2 capture than conventional oxy-fuel combustion or post-combustion absorption. While much work has been done on CLC in the past two decades, the issue of multi-fuel compatibility has not been addressed sufficiently, especially with regard to plant layout and reactor design. In the present work, it is shown that this is non-trivial in the case of a CLC-based power plant. The underlying factors have been examined in depth and design criteria for fuel compatibility have been formulated. Based on these, a layout has been developed for a power plant which can run with either natural gas or syngas without requiring equipment changes either on the steam side or on the furnace side. The layout accounts for the higher CO 2 compression costs associated with the use of syngas in place of natural gas. The ideal thermodynamic cycle efficiency, after accounting for the energy penalty of CO 2 compression, is 43.11% and 41.08%, when a supercritical steam cycle is used with natural gas and syngas, respectively. It is shown that fuel switching can be enabled by incorporating the compatibility conditions at the design stage itself. - Highlights: • Concept of fuel sensitivity of plant layout with carbon capture and sequestration. • Power plant layout for natural gas and syngas as fuels. • Criteria for compatibility of air and fuel reactors for dual fuel mode operation. • Layout of a plant for carbon-neutral or carbon negative power generation

  7. Hydrodynamic analysis of a three-fluidized bed reactor cold flow model for chemical looping hydrogen generation. Pressure characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhipeng; Xiang, Wenguo; Chen, Shiyi; Wang, Dong [Southeast Univ., Nanjing (China). School of Energy and Environment

    2013-07-01

    Chemical looping hydrogen generation (CLHG) can produce pure hydrogen with inherent separation of CO{sub 2} from fossils fuel. The process involves a metal oxide, as an oxygen carrier, such as iron oxide. The CLHG system consists of three reactors: a fuel reactor (FR), a steam reactor (SR) and an air reactor (AR). In the FR, the fuel gases react with iron oxides (hematite Fe{sub 2}O{sub 3}, magnetite Fe{sub 3}O{sub 4}, wuestite FeO), generating reduced iron oxides (FeO or even Fe), and with full conversion of gaseous fuels, pure CO{sub 2} can be obtained after cooling the flue gas from the fuel reactor; in the SR, FeO and Fe reacts with steam to generate magnetite (Fe{sub 3}O{sub 4}) and H{sub 2}, the latter representing the final target product of the process; in the AR, the magnetite is oxidized back to hematite which is used in another cycle. A cold flow model of three-fluidized bed for CLHG corresponding to 50 KW hot units has been built. A major novelty of this facility is the compact fuel reactor, which integrates a bubble and a fast fluidized bed to avoid the incomplete conversion of the fuel gas caused by the thermodynamics equilibrium. In order to study the pressure characteristics and the solids concentration of the system, especially in the fuel reactor, the gas velocity of three reactors, gas flow of L-type value, total solids inventory (TSI) and the secondary air of fuel reactor were varied. Results show that the pressure and the solids concentration are strongly influenced by the fluidizing-gas velocity of three reactors. Moreover, the entrainment of the upper part of fuel reactor increases as the total solids inventory increases, and the operating range of the FR can be changed by introducing secondary air or increasing the total solids inventory.

  8. Thermodynamic and experimental study on heat transfer mechanism of miniature loop heat pipe with water-copper nanofluid

    Science.gov (United States)

    Wang, Xiao-wu; Wan, Zhen-ping; Tang, Yong

    2018-02-01

    A miniature loop heat pipe (mLHP) is a promising device for heat dissipation of electronic products. Experimental study of heat transfer performance of an mLHP employing Cu-water nanofluid as working fluid was conducted. It is found that, when input power is above 25 W, the temperature differences between the evaporator wall and vapor of nanofluid, Te - Tv, and the total heat resistance of mLHP using nanofluid are always lower than those of mLHP using de-ionized water. The values of Te - Tv and total heat resistance of mLHP using nanofluid with concentration 1.5 wt. % are the lowest, while when the input power is 25 W, the values of Te - Tv and total heat resistance of mLHP using de-ionized water are even lower than those of mLHP using nanofluid with concentration 2.0 wt. %. At larger input power, the dominant interaction is collision between small bubbles and nanoparticles which can facilitate heat transfer. While at lower input power, nanoparticles adhere to the surface of large bubble. This does not benefit boiling heat transfer. For mLHP using nanofluid with larger concentration, for example 2.0%, the heat transfer may even be worse compared with using de-ionized water at lower input power. The special structure of the mLHP in this study, two separated chambers in the evaporator, produces an extra pressure difference and contributes to the heat transfer performance of the mLHP.

  9. Experimental Study on Hydrate Induction Time of Gas-Saturated Water-in-Oil Emulsion using a High-Pressure Flow Loop

    Directory of Open Access Journals (Sweden)

    Lv X.F.

    2015-11-01

    Full Text Available Hydrate is one of the critical precipitates which have to be controlled for subsea flow assurance. The induction time of hydrate is therefore a significant parameter. However, there have been few studies on the induction time of the natural gas hydrate formation in a flow loop system. Consequently, a series of experiments were firstly performed, including water, natural gas and Diesel oil, on the hydrate induction time under various conditions such as the supercooling and supersaturation degree, water cut, anti-agglomerant dosage, etc. The experiments were conducted in a high-pressure hydrate flow loop newly constructed in the China University of Petroleum (Beijing, and dedicated to flow assurance studies. Then, based on previous research, this study puts forward a method for induction time, which is characterized by clear definition, convenient measurement and good generality. Furthermore, we investigated the influences of the experimental parameters and analyzed the experimental phenomena for the hydrate induction time in a flowing system.

  10. Ab initio Quantum Chemical and Experimental Reaction Kinetics Studies in the Combustion of Bipropellants

    Science.gov (United States)

    2017-03-24

    NUMBER (Include area code) 24 March 2017 Briefing Charts 01 March 2017 - 31 March 2017 Ab initio Quantum Chemical and Experimental Reaction Kinetics...Laboratory AFRL/RQRS 1 Ara Road Edwards AFB, CA 93524 *Email: ghanshyam.vaghjiani@us.af.mil Ab initio Quantum Chemical and Experimental Reaction ...Clearance 17161 Zador et al., Prog. Energ. Combust. Sci., 37 371 (2011) Why Quantum Chemical Reaction Kinetics Studies? DISTRIBUTION A: Approved for

  11. Copper-manganese mixed oxides: CO2-selectivity, stable, and cyclic performance for chemical looping combustion of methane.

    Science.gov (United States)

    Mungse, Pallavi; Saravanan, Govindachetty; Uchiyama, Tomoki; Nishibori, Maiko; Teraoka, Yasutake; Rayalu, Sadhana; Labhsetwar, Nitin

    2014-09-28

    Chemical looping combustion (CLC) is a key technology for oxy-fuel combustion with inherent separation of CO2 from a flue gas, in which oxygen is derived from a solid oxygen carrier. Multi-cycle CLC performance and the product selectivity towards CO2 formation were achieved using mixed oxide of Cu and Mn (CuMn2O4) (Fd3[combining macron]m, a = b = c = 0.83 nm) as an oxygen carrier. CuMn2O4 was prepared by the co-precipitation method followed by annealing at 900 °C using copper(II) nitrate trihydrate and manganese(II) nitrate tetrahydrate as metal precursors. CuMn2O4 showed oxygen-desorption as well as reducibility at elevated temperatures under CLC conditions. The lattice of CuMn2O4 was altered significantly at higher temperature, however, it was reinstated virtually upon cooling in the presence of air. CuMn2O4 was reduced to CuMnO2, Mn3O4, and Cu2O phases at the intermediate stages, which were further reduced to metallic Cu and MnO upon the removal of reactive oxygen from their lattice. CuMn2O4 showed a remarkable activity towards methane combustion reaction at 750 °C. The reduced phase of CuMn2O4 containing Cu and MnO was readily reinstated when treated with air or oxygen at 750 °C, confirming efficient regeneration of the oxygen carrier. Neither methane combustion efficiency nor oxygen carrying capacity was altered with the increase of CLC cycles at any tested time. The average oxygen carrying capacity of CuMn2O4 was estimated to be 114 mg g(-1), which was not altered significantly with the repeated CLC cycles. Pure CO2 but no CO, which is one of the possible toxic by-products, was formed solely upon methane combustion reaction of CuMn2O4. CuMn2O4 shows potential as a practical CLC material both in terms of multi-cycle performance and product selectivity towards CO2 formation.

  12. Experimental and quantum chemical studies on corrosion inhibition ...

    Indian Academy of Sciences (India)

    The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also used to ...

  13. Experimental and quantum chemical studies on corrosion inhibition ...

    Indian Academy of Sciences (India)

    The results showed that FLU can act as a good cor- rosion inhibitor for steel in hydrochloric acid solution at different temperatures and it can inhibit steel corrosion up to 95%. The adsorption followed the Langmuir isotherm and the thermodynamic parameters were also determined and discussed. Quantum chemical studies ...

  14. Experimental and quantum chemical studies on corrosion inhibition ...

    Indian Academy of Sciences (India)

    transfer resistance and double-layer capacitance that confirmed strong adsorption of inhibitors on the MS surface. The inhibition action of these compounds was assumed to occur via adsorption on the steel surface through the active centres contained in the molecules. Furthermore, quantum chemical calculations have ...

  15. Experimental and quantum chemical studies on corrosion inhibition ...

    Indian Academy of Sciences (India)

    Abstract. The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also ...

  16. Experimental and quantum chemical studies on corrosion inhibition

    Indian Academy of Sciences (India)

    The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also used to ...

  17. A proof-of-principle simulation for closed-loop control based on preexisting experimental thalamic DBS-enhanced instrumental learning.

    Science.gov (United States)

    Wang, Ching-Fu; Yang, Shih-Hung; Lin, Sheng-Huang; Chen, Po-Chuan; Lo, Yu-Chun; Pan, Han-Chi; Lai, Hsin-Yi; Liao, Lun-De; Lin, Hui-Ching; Chen, Hsu-Yan; Huang, Wei-Chen; Huang, Wun-Jhu; Chen, You-Yin

    Deep brain stimulation (DBS) has been applied as an effective therapy for treating Parkinson's disease or essential tremor. Several open-loop DBS control strategies have been developed for clinical experiments, but they are limited by short battery life and inefficient therapy. Therefore, many closed-loop DBS control systems have been designed to tackle these problems by automatically adjusting the stimulation parameters via feedback from neural signals, which has been reported to reduce the power consumption. However, when the association between the biomarkers of the model and stimulation is unclear, it is difficult to develop an optimal control scheme for other DBS applications, i.e., DBS-enhanced instrumental learning. Furthermore, few studies have investigated the effect of closed-loop DBS control for cognition function, such as instrumental skill learning, and have been implemented in simulation environments. In this paper, we proposed a proof-of-principle design for a closed-loop DBS system, cognitive-enhancing DBS (ceDBS), which enhanced skill learning based on in vivo experimental data. The ceDBS acquired local field potential (LFP) signal from the thalamic central lateral (CL) nuclei of animals through a neural signal processing system. A strong coupling of the theta oscillation (4-7 Hz) and the learning period was found in the water reward-related lever-pressing learning task. Therefore, the theta-band power ratio, which was the averaged theta band to averaged total band (1-55 Hz) power ratio, could be used as a physiological marker for enhancement of instrumental skill learning. The on-line extraction of the theta-band power ratio was implemented on a field-programmable gate array (FPGA). An autoregressive with exogenous inputs (ARX)-based predictor was designed to construct a CL-thalamic DBS model and forecast the future physiological marker according to the past physiological marker and applied DBS. The prediction could further assist the design of

  18. Determination of the Clean Air Delivery Rate (CADR) of Photocatalytic Oxidation (PCO) Purifiers for Indoor Air Pollutants Using a Closed-Loop Reactor. Part II: Experimental Results.

    Science.gov (United States)

    Héquet, Valérie; Batault, Frédéric; Raillard, Cécile; Thévenet, Frédéric; Le Coq, Laurence; Dumont, Éric

    2017-03-06

    The performances of a laboratory PhotoCatalytic Oxidation (PCO) device were determined using a recirculation closed-loop pilot reactor. The closed-loop system was modeled by associating equations related to two ideal reactors: a perfectly mixed reservoir with a volume of V R = 0.42 m³ and a plug flow system corresponding to the PCO device with a volume of V P = 5.6 × 10 -3 m³. The PCO device was composed of a pleated photocatalytic filter (1100 cm²) and two 18-W UVA fluorescent tubes. The Clean Air Delivery Rate (CADR) of the apparatus was measured under different operating conditions. The influence of three operating parameters was investigated: (i) light irradiance I from 0.10 to 2.0 mW·cm -2 ; (ii) air velocity v from 0.2 to 1.9 m·s -1 ; and (iii) initial toluene concentration C₀ (200, 600, 1000 and 4700 ppbv). The results showed that the conditions needed to apply a first-order decay model to the experimental data (described in Part I) were fulfilled. The CADR values, ranging from 0.35 to 3.95 m³·h -1 , were mainly dependent on the light irradiance intensity. A square root influence of the light irradiance was observed. Although the CADR of the PCO device inserted in the closed-loop reactor did not theoretically depend on the flow rate (see Part I), the experimental results did not enable the confirmation of this prediction. The initial concentration was also a parameter influencing the CADR, as well as the toluene degradation rate. The maximum degradation rate r max ranged from 342 to 4894 ppbv/h. Finally, this study evidenced that a recirculation closed-loop pilot could be used to develop a reliable standard test method to assess the effectiveness of PCO devices.

  19. Determination of the Clean Air Delivery Rate (CADR of Photocatalytic Oxidation (PCO Purifiers for Indoor Air Pollutants Using a Closed-Loop Reactor. Part II: Experimental Results

    Directory of Open Access Journals (Sweden)

    Valérie Héquet

    2017-03-01

    Full Text Available The performances of a laboratory PhotoCatalytic Oxidation (PCO device were determined using a recirculation closed-loop pilot reactor. The closed-loop system was modeled by associating equations related to two ideal reactors: a perfectly mixed reservoir with a volume of VR = 0.42 m3 and a plug flow system corresponding to the PCO device with a volume of VP = 5.6 × 10−3 m3. The PCO device was composed of a pleated photocatalytic filter (1100 cm2 and two 18-W UVA fluorescent tubes. The Clean Air Delivery Rate (CADR of the apparatus was measured under different operating conditions. The influence of three operating parameters was investigated: (i light irradiance I from 0.10 to 2.0 mW·cm−2; (ii air velocity v from 0.2 to 1.9 m·s−1; and (iii initial toluene concentration C0 (200, 600, 1000 and 4700 ppbv. The results showed that the conditions needed to apply a first-order decay model to the experimental data (described in Part I were fulfilled. The CADR values, ranging from 0.35 to 3.95 m3·h−1, were mainly dependent on the light irradiance intensity. A square root influence of the light irradiance was observed. Although the CADR of the PCO device inserted in the closed-loop reactor did not theoretically depend on the flow rate (see Part I, the experimental results did not enable the confirmation of this prediction. The initial concentration was also a parameter influencing the CADR, as well as the toluene degradation rate. The maximum degradation rate rmax ranged from 342 to 4894 ppbv/h. Finally, this study evidenced that a recirculation closed-loop pilot could be used to develop a reliable standard test method to assess the effectiveness of PCO devices.

  20. Experimental studies and computational benchmark on heavy liquid metal natural circulation in a full height-scale test loop for small modular reactors

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Yong-Hoon, E-mail: chaotics@snu.ac.kr [Department of Energy Systems Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Cho, Jaehyun [Korea Atomic Energy Research Institute, 111 Daedeok-daero, 989 Beon-gil, Yuseong-gu, Daejeon 34057 (Korea, Republic of); Lee, Jueun; Ju, Heejae; Sohn, Sungjune; Kim, Yeji; Noh, Hyunyub; Hwang, Il Soon [Department of Energy Systems Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of)

    2017-05-15

    Highlights: • Experimental studies on natural circulation for lead-bismuth eutectic were conducted. • Adiabatic wall boundaries conditions were established by compensating heat loss. • Computational benchmark with a system thermal-hydraulics code was performed. • Numerical simulation and experiment showed good agreement in mass flow rate. • An empirical relation was formulated for mass flow rate with experimental data. - Abstract: In order to test the enhanced safety of small lead-cooled fast reactors, lead-bismuth eutectic (LBE) natural circulation characteristics have been studied. We present results of experiments with LBE non-isothermal natural circulation in a full-height scale test loop, HELIOS (heavy eutectic liquid metal loop for integral test of operability and safety of PEACER), and the validation of a system thermal-hydraulics code. The experimental studies on LBE were conducted under steady state as a function of core power conditions from 9.8 kW to 33.6 kW. Local surface heaters on the main loop were activated and finely tuned by trial-and-error approach to make adiabatic wall boundary conditions. A thermal-hydraulic system code MARS-LBE was validated by using the well-defined benchmark data. It was found that the predictions were mostly in good agreement with the experimental data in terms of mass flow rate and temperature difference that were both within 7%, respectively. With experiment results, an empirical relation predicting mass flow rate at a non-isothermal, adiabatic condition in HELIOS was derived.

  1. The strange-quark chemical potential as an experimentally accessible 'order parameter' of the deconfinement phase transition for finite baryon density

    International Nuclear Information System (INIS)

    Panagiotou, Apostolos D; Katsas, Panayiotis G

    2003-01-01

    We consider the change of the strange-quark chemical potential in the phase diagram of nuclear matter, employing the Wilson loop and scalar quark condensate order parameters, mass-scaled partition functions and enforcing flavour conservation. Assuming the region beyond the hadronic phase to be described by massive, correlated and interacting quarks, in the spirit of lattice and effective QCD calculations, we find the strange-quark chemical potential to change sign: from positive in the hadronic phase, to zero upon deconfinement, to negative in the partonic domain. We propose this change in the sign of the strange-quark chemical potential to be an experimentally accessible order parameter and a unique, concise and well-defined indication of the quark-deconfinement phase transition in nuclear matter

  2. Verification of SACI-2 computer code comparing with experimental results of BIBLIS-A and LOOP-7 computer code

    International Nuclear Information System (INIS)

    Soares, P.A.; Sirimarco, L.F.

    1984-01-01

    SACI-2 is a computer code created to study the dynamic behaviour of a PWR nuclear power plant. To evaluate the quality of its results, SACI-2 was used to recalculate commissioning tests done in BIBLIS-A nuclear power plant and to calculate postulated transients for Angra-2 reactor. The results of SACI-2 computer code from BIBLIS-A showed as much good agreement as those calculated with the KWU Loop 7 computer code for Angra-2. (E.G.) [pt

  3. An experimental investigation of chemical communication in the polar bear

    Science.gov (United States)

    Owen, Megan A.; Swaisgood, Ronald R.; Slocomb, C.; Amstrup, Steven C.; Durner, George M.; Simac, Kristin S.; Pessier, Allan P.

    2015-01-01

    The polar bear (Ursus maritimus), with its wide-ranging movements, solitary existence and seasonal reproduction, is expected to favor chemosignaling over other communication modalities. However, the topography of its Arctic sea ice habitat is generally lacking in stationary vertical substrates routinely used for targeted scent marking in other bears. These environmental constraints may have shaped a marking strategy, unique to polar bears, for widely dispersed continuous dissemination of scent via foot pads. To investigate the role of chemical communication, pedal scents were collected from free-ranging polar bears of different sex and reproductive classes captured on spring sea ice in the Beaufort and Chukchi seas, and presented in a controlled fashion to 26 bears in zoos. Results from behavioral bioassays indicated that bears, especially females, were more likely to approach conspecific scent during the spring than the fall. Male flehmen behavior, indicative of chemosignal delivery to the vomeronasal organ, differentiated scent donor by sex and reproductive condition. Histologic examination of pedal skin collected from two females indicated prominent and profuse apocrine glands in association with large compound hair follicles, suggesting that they may produce scents that function as chemosignals. These results suggest that pedal scent, regardless of origin, conveys information to conspecifics that may facilitate social and reproductive behavior, and that chemical communication in this species has been adaptively shaped by environmental constraints of its habitat. However, continuously distributed scent signals necessary for breeding behavior may prove less effective if current and future environmental conditions cause disruption of scent trails due to increased fracturing of sea ice.

  4. Chemical Structure Identification in Metabolomics: Computational Modeling of Experimental Features

    Directory of Open Access Journals (Sweden)

    Lochana C Menikarachchi

    2013-02-01

    Full Text Available The identification of compounds in complex mixtures remains challenging despite recent advances in analytical techniques. At present, no single method can detect and quantify the vast array of compounds that might be of potential interest in metabolomics studies. High performance liquid chromatography/mass spectrometry (HPLC/MS is often considered the analytical method of choice for analysis of biofluids. The positive identification of an unknown involves matching at least two orthogonal HPLC/MS measurements (exact mass, retention index, drift time etc. against an authentic standard. However, due to the limited availability of authentic standards, an alternative approach involves matching known and measured features of the unknown compound with computationally predicted features for a set of candidate compounds downloaded from a chemical database. Computationally predicted features include retention index, ECOM50 (energy required to decompose 50% of a selected precursor ion in a collision induced dissociation cell, drift time, whether the unknown compound is biological or synthetic and a collision induced dissociation (CID spectrum. Computational predictions are used to filter the initial “bin” of candidate compounds. The final output is a ranked list of candidates that best match the known and measured features. In this mini review, we discuss cheminformatics methods underlying this database search-filter identification approach.

  5. Interaction between {sup 99}Tc{sup m}-hydroxmethylene diphosphonate and loop-diuretics in an experimental mouse system

    Energy Technology Data Exchange (ETDEWEB)

    Cronhjort, M. [Dept. of Diagnostic Radiology, Karolinska Hospital, Stockholm (Sweden); Sjoeberg, H.E. [Dept. of Endocrinology, Karolinska Hospital, Stockholm (Sweden); Schnell, P.O. [Dept. of Hospital Physics, Karolinska Hospital, Stockholm (Sweden); Jacobsson, H. [Dept. of Diagnostic Radiology, Karolinska Hospital, Stockholm (Sweden)

    1994-12-31

    The image quality at bone scintigraphy depends largely on the bone/soft-tissue activity ratio. This varies considerably between different patients and may sometimes be strongly reduced. The ratio increases with time due to urinary excretion of extracelluar activity. The possibility to utilize the phosphaturic effect of loop-diuretics to enhance the excretion of the soft tissue activity caused by radiolabeled phosphonate compounds at bone scintigraphy has been studied. Three loop-diuretics (Bumetanide, Ethacrynic acid and Furosemide) were injected at different times in relation to {sup 99}Tc{sup m}-Hydroxymethylene diphosphonate (HDP) in mice. By assessing the activity of different organs as well as of peripheral blood by a gamma-counter, the activity distribution in the animals was established. Administration of diuretics together with, or after HDP has a negative influence on the quality of the potential HDP-image. Administration of diuretics prior to the radiopharmaceutical slightly improves the image quality, but not to an extent justifying it use for this purpose in practice. The complex effects on HDP may be explained by the influence of Furosemide on calcium, pH and on blood plasma volume and their hormonal consequences. (orig.) [Deutsch] Bei der Knochenszintigraphie haengt die Bildqualitaet hauptsaechlich von der Quote der Isotopenaktivitaet in den Knochen und in den Weichteilen ab. Die extrazellulaere Weichteilaktivitaet wird durch die Nieren ausgeschieden, zur Steigerung der Quote fuehrend. Die Moeglichkeit die Diuretica wegen ihrer Wirkung die extrazellulaeren Isotopen aus dem Koerper auszuschneiden zu benuetzen ist hier untersucht worden. Diesbezueglich hat man insgesamt drei Typen von Loop-Diuretica (Bumetanid, Ethacrynsaeure und Furosemid) verwendet. Die Diuretica hat man den Maeusen bei verschiedenen Zeitpunkten im Verhaeltnis zu dem {sup 99}Tc{sup m}-HDP (HDP) zugefuehrt. Um die Verteilung des Isotops in den Tierkoerpern festzustellen, ist die

  6. Experimental study of chemical embolus therapy combined with radiotherapy for VX2 bone tumors

    International Nuclear Information System (INIS)

    Yamaguchi, Hiroshi; Mochizuki, Kazuo; Ishii, Yoshiaki

    2000-01-01

    We conducted an experimental study, using a combination of coarse crystal cisplatin and radiotherapy for bone tumors, to evaluate the possibility of the clinical application of chemical embolus therapy in the field of orthopedic surgery. Experimental femoral bone tumors were produced, in rabbits, using VX2 carcinoma. The rabbits were allocated to five groups: untreated control, embolus, chemical embolus, irradiation alone, and chemical embolus and irradiation combination. These therapies were evaluated comparatively, in terms of local antitumor effects (including body weight, X-ray findings, angiography, and histopathology) and in terms of inhibition of pulmonary metastasis. Local antitumor effects, as evaluated by all parameters, except for body weight, were significantly greater for the chemical and irradiation combination group than for the chemical embolus, irradiation alone, untreated control, and embolus groups. There was no significant difference in the inhibition of pulmonary metastasis among the chemical embolus and irradiation combination, chemical embolus, and irradiation alone groups. These findings demonstrated the synergistic effect of the combination of chemical embolus therapy and radiotherapy. In this study, however, no significant difference was found between the chemical embolus therapy alone and the combination therapy groups in the inhibitory effect on pulmonary tumor metastasis, suggesting the need to conduct combination therapy repeatedly in the clinical setting. (author)

  7. Experimental Simulations for Elimination of Biological and/or Chemical Agents

    Science.gov (United States)

    Hong, Yong C.; Kim, Jeong H.; Uhm, Han S.

    2003-10-01

    The threat of biological and/or chemical agents in a domestic terrorist attack and in military conflict is increasing worldwide. The 2oo1 anthrax terror throughout the USA, 1995 sarin nerve gas attack on Tokyo subway, and the like are evident for this threat. Elimination and decontamination of biological and/or chemical agents are needed for such an attack. Experimental simulation for elimination of biological and/or chemical agents using an atmospheric-pressure microwave plasma torch is carried out. The elimination of biological and/or chemical agents through the vitrification or burnout of sewage sludge powders and the decomposition of toluene gas as a chemical agent stimulant is presented. A detailed characterization for the elimination of the simulant chemicals using Fourier Transform Infrared (FT-IR) and Gas Chromatography (GC) is also presented.

  8. Exploring the Use of Design of Experiments in Industrial Processes Operating Under Closed-Loop Control

    DEFF Research Database (Denmark)

    Capaci, Francesca; Kulahci, Murat; Vanhatalo, Erik

    2017-01-01

    Industrial manufacturing processes often operate under closed-loop control, where automation aims to keep important process variables at their set-points. In process industries such as pulp, paper, chemical and steel plants, it is often hard to find production processes operating in open loop....... Instead, closed-loop control systems will actively attempt to minimize the impact of process disturbances. However, we argue that an implicit assumption in most experimental investigations is that the studied system is open loop, allowing the experimental factors to freely affect the important system...... responses. This scenario is typically not found in process industries. The purpose of this article is therefore to explore issues of experimental design and analysis in processes operating under closed-loop control and to illustrate how Design of Experiments can help in improving and optimizing...

  9. Spectroscopic and chemical reactivity analysis of D-Myo-Inositol using quantum chemical approach and its experimental verification

    Science.gov (United States)

    Mishra, Devendra P.; Srivastava, Anchal; Shukla, R. K.

    2017-07-01

    This paper describes the spectroscopic (^1H and ^{13}C NMR, FT-IR and UV-Visible), chemical, nonlinear optical and thermodynamic properties of D-Myo-Inositol using quantum chemical technique and its experimental verification. The structural parameters of the compound are determined from the optimized geometry by B3LYP method with 6 {-}311{+}{+}G(d,p) basis set. It was found that the optimized parameters thus obtained are almost in agreement with the experimental ones. A detailed interpretation of the infrared spectra of D-Myo-Inositol is also reported in the present work. After optimization, the proton and carbon NMR chemical shifts of the studied compound are calculated using GIAO and 6 {-}311{+}{+}G(d,p) basis set. The search of organic materials with improved charge transfer properties requires precise quantum chemical calculations of space-charge density distribution, state and transition dipole moments and HOMO-LUMO states. The nature of the transitions in the observed UV-Visible spectrum of the compound has been studied by the time-dependent density functional theory (TD-DFT). The global reactivity descriptors like chemical potential, electronegativity, hardness, softness and electrophilicity index, have been calculated using DFT. The thermodynamic calculation related to the title compound was also performed at B3LYP/ 6 {-}311{+}{+}G(d,p) level of theory. The standard statistical thermodynamic functions like heat capacity at constant pressure, entropy and enthalpy change were obtained from the theoretical harmonic frequencies of the optimized molecule. It is observed that the values of heat capacity, entropy and enthalpy increase with increase in temperature from 100 to 1000 K, which is attributed to the enhancement of molecular vibration with the increase in temperature.

  10. Solid-Fueled Pressurized Chemical Looping with Flue-Gas Turbine Combined Cycle for Improved Plant Efficiency and CO2 Capture

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kunlei [Univ. of Kentucky, Lexington, KY (United States); Chen, Liangyong [Univ. of Kentucky, Lexington, KY (United States); Zhang, Yi [Univ. of Kentucky, Lexington, KY (United States); Richburg, Lisa [Univ. of Kentucky, Lexington, KY (United States); Simpson, James [WorleyParsons Group Inc., Reading, PA (United States); White, Jay [WorleyParsons Group Inc., Reading, PA (United States); Rossi, Gianalfredo [WorleyParsons Group Inc., Reading, PA (United States)

    2013-12-31

    The purpose of this document is to report the final result of techno-economic analysis for the proposed 550MWe integrated pressurized chemical looping combustion combined cycle process. An Aspen Plus based model is delivered in this report along with the results from three sensitivity scenarios including the operating pressure, excess air ratio and oxygen carrier performance. A process flow diagram and detailed stream table for the base case are also provided with the overall plant energy balance, carbon balance, sulfur balance and water balance. The approach to the process and key component simulation are explained. The economic analysis (OPEX and CAPX) on four study cases via DOE NETL Reference Case 12 are presented and explained.

  11. Experimental study on the thermal performance of a small-scale loop heat pipe with polypropylene wick

    International Nuclear Information System (INIS)

    Boo, Joon Hong; Chung, Won Bok

    2005-01-01

    A small-scale Loop Heat Pipe (LHP) with polypropylene wick was fabricated and tested for investigation of its thermal performance. The container and tubing of the system were made of stainless steel and several working fluids were tested including methanol, ethanol, and acetone. The heating area was 35 mm x 35 mm and nine axial grooves were provided in the evaporator to provide vapor passages. The pore size of the polypropylene wick inside the evaporator was varied from 0.5 μm to 25 μm. The inner diameter of liquid and vapor transport lines were 2.0 mm and 4.0 mm, respectively and the length of which were 0.5 mm. The size of condenser was 40 mm (W) x 50 mm (L) in which ten coolant paths were provided. Start-up characteristics as well as steady-state performance was analyzed and discussed. The minimum thermal load of 10 W (0.8W/cam 2 ) and maximum thermal load of 80 W (6.5 W/cm 2 ) were achieved using methanol as working fluid with the condenser temperature of 20 deg. C with horizontal position

  12. Thermodynamic Possibilities and Constraints for Pure Hydrogen Production by Iron Based Chemical Looping Process at Lower Temperatures.

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Karel; Slowinski, G.; Rogut, J.; Baxter, D.

    2007-01-01

    Roč. 48, 12 (2007) , s. 3063-3073 ISSN 0196-8904 Institutional research plan: CEZ:AV0Z40720504 Keywords : iron * hydrogen production * magnetite Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.180, year: 2007

  13. The Automatic Neuroscientist: A framework for optimizing experimental design with closed-loop real-time fMRI.

    Science.gov (United States)

    Lorenz, Romy; Monti, Ricardo Pio; Violante, Inês R; Anagnostopoulos, Christoforos; Faisal, Aldo A; Montana, Giovanni; Leech, Robert

    2016-04-01

    Functional neuroimaging typically explores how a particular task activates a set of brain regions. Importantly though, the same neural system can be activated by inherently different tasks. To date, there is no approach available that systematically explores whether and how distinct tasks probe the same neural system. Here, we propose and validate an alternative framework, the Automatic Neuroscientist, which turns the standard fMRI approach on its head. We use real-time fMRI in combination with modern machine-learning techniques to automatically design the optimal experiment to evoke a desired target brain state. In this work, we present two proof-of-principle studies involving perceptual stimuli. In both studies optimization algorithms of varying complexity were employed; the first involved a stochastic approximation method while the second incorporated a more sophisticated Bayesian optimization technique. In the first study, we achieved convergence for the hypothesized optimum in 11 out of 14 runs in less than 10 min. Results of the second study showed how our closed-loop framework accurately and with high efficiency estimated the underlying relationship between stimuli and neural responses for each subject in one to two runs: with each run lasting 6.3 min. Moreover, we demonstrate that using only the first run produced a reliable solution at a group-level. Supporting simulation analyses provided evidence on the robustness of the Bayesian optimization approach for scenarios with low contrast-to-noise ratio. This framework is generalizable to numerous applications, ranging from optimizing stimuli in neuroimaging pilot studies to tailoring clinical rehabilitation therapy to patients and can be used with multiple imaging modalities in humans and animals. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  14. An Experimental Framework for Generating Evolvable Chemical Systems in the Laboratory

    Science.gov (United States)

    Baum, David A.; Vetsigian, Kalin

    2017-12-01

    Most experimental work on the origin of life has focused on either characterizing the chemical synthesis of particular biochemicals and their precursors or on designing simple chemical systems that manifest life-like properties such as self-propagation or adaptive evolution. Here we propose a new class of experiments, analogous to artificial ecosystem selection, where we select for spontaneously forming self-propagating chemical assemblages in the lab and then seek evidence of a response to that selection as a key indicator that life-like chemical systems have arisen. Since surfaces and surface metabolism likely played an important role in the origin of life, a key experimental challenge is to find conditions that foster nucleation and spread of chemical consortia on surfaces. We propose high-throughput screening of a diverse set of conditions in order to identify combinations of "food," energy sources, and mineral surfaces that foster the emergence of surface-associated chemical consortia that are capable of adaptive evolution. Identification of such systems would greatly advance our understanding of the emergence of self-propagating entities and the onset of adaptive evolution during the origin of life.

  15. CFD Simulation and Experimental Measurement of Gas Holdup and Liquid Interstitial Velocity in Internal Loop Airlift Reactor

    Czech Academy of Sciences Publication Activity Database

    Šimčík, Miroslav; Mota, A.; Růžička, Marek; Vicente, A.; Teixeira, J.

    2011-01-01

    Roč. 66, č. 14 (2011), s. 3268-3279 ISSN 0009-2509. [International Conference on Gas–Liquid and Gas–Liquid–Solid Reactor Engineering /10./. Braga, 26.06.2011-29.06.2011] R&D Projects: GA ČR GA104/07/1110 Grant - others:FCT(PT) SFRH/BD/37082/2007 Institutional research plan: CEZ:AV0Z40720504 Keywords : cfd * airlift * hydrodynamics Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.431, year: 2011

  16. siRNAmod: A database of experimentally validated chemically modified siRNAs.

    Science.gov (United States)

    Dar, Showkat Ahmad; Thakur, Anamika; Qureshi, Abid; Kumar, Manoj

    2016-01-28

    Small interfering RNA (siRNA) technology has vast potential for functional genomics and development of therapeutics. However, it faces many obstacles predominantly instability of siRNAs due to nuclease digestion and subsequently biologically short half-life. Chemical modifications in siRNAs provide means to overcome these shortcomings and improve their stability and potency. Despite enormous utility bioinformatics resource of these chemically modified siRNAs (cm-siRNAs) is lacking. Therefore, we have developed siRNAmod, a specialized databank for chemically modified siRNAs. Currently, our repository contains a total of 4894 chemically modified-siRNA sequences, comprising 128 unique chemical modifications on different positions with various permutations and combinations. It incorporates important information on siRNA sequence, chemical modification, their number and respective position, structure, simplified molecular input line entry system canonical (SMILES), efficacy of modified siRNA, target gene, cell line, experimental methods, reference etc. It is developed and hosted using Linux Apache MySQL PHP (LAMP) software bundle. Standard user-friendly browse, search facility and analysis tools are also integrated. It would assist in understanding the effect of chemical modifications and further development of stable and efficacious siRNAs for research as well as therapeutics. siRNAmod is freely available at: http://crdd.osdd.net/servers/sirnamod.

  17. Experimental Study on the Application as the Mold Release Agent of a Chemically Adsorbed Fluorocarbon Film

    Science.gov (United States)

    Yamamoto, Hiroyuki; Ohkubo, Yuji; Ogawa, Kazufumi; Utsumi, Kunihiro

    In this study, the use of an extremely thin and chemically adsorbed fluorocarbon film with no influences on the dimension accuracy of the mold geometries on an injection mold (The thickness is about 1 nanometer order.) was experimentally studied as a great releasing agent to reduce the ejection resistance without any influences on the dimensional accuracy of the mold geometries. As a result, this surface treatment on the mold was practically confirmed not only to be very beneficial for the polymers those are difficult to release from the mold surface such as silicone, urethane and elastomers, but also to be useful for making high precision products such as optical components and chemical chips.

  18. Gas-phase hydrosilylation of cyclohexene in an experimental radiation-chemical accelerator apparatus

    International Nuclear Information System (INIS)

    Pecherkin, A.S.; Sidorov, V.I.; Chernyshev, E.A.

    1992-01-01

    A process for the synthesis of methylcyclohexyldichlorosilane (a basic monomer for the production of organosilicon photoresists) has been investigated and perfected on an experimental apparatus with an ELV-2 electron accelerator; this synthesis involves gas-phase radiation-induced hydrosilylation of cyclohexene by methyldichlorosilane. Basic characteristics of the yield of the desired product under static conditions were determined. With the help of experiments on the synthesis of methylcyclohexyldichlorosilane in a flow- through mode, the technical features of the process of radiation-chemical hydrosilylation of cyclohexene on an accelerator apparatus were determined and studied, the optimal conditions for the synthesis were determined, and an experimental batch of the desired product was produced

  19. Chemical constitution, physical properties, and biocompatibility of experimentally manufactured Portland cement.

    Science.gov (United States)

    Hwang, Yun-Chan; Kim, Do-Hee; Hwang, In-Nam; Song, Sun-Ju; Park, Yeong-Joon; Koh, Jeong-Tae; Son, Ho-Hyun; Oh, Won-Mann

    2011-01-01

    An experimental Portland cement was manufactured with pure raw materials under controlled laboratory conditions. The aim of this study was to compare the chemical constitution, physical properties, and biocompatibility of experimentally manufactured Portland cement with those of mineral trioxide aggregate (MTA) and Portland cement. The composition of the cements was determined by scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDAX). The setting time and compressive strength were tested. The biocompatibility was evaluated by using SEM and XTT assay. SEM and EDAX revealed the experimental Portland cement to have a similar composition to Portland cement. The setting time of the experimental Portland cement was significantly shorter than that of MTA and Portland cement. The compressive strength of the experimental Portland cement was lower than that of MTA and Portland cement. The experimental Portland cement showed a similar biocompatibility to MTA. The experimental Portland cement might be considered as a possible substitute for MTA in clinical usage after further testing. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. Experimental and theoretical study on chemically semi-amplified resist AR-P 6200

    Science.gov (United States)

    Kostic, I.; Vutova, K.; Andok, R.; Barak, V.; Bencurova, A.; Ritomsky, R.; Tanaka, T.

    2018-03-01

    Experimental and simulation results are presented and discussed on electron-beam lithography (EBL) nano-structuring using the positive chemically semi-amplified electron-beam resist AR-P 6200 (CSAR 62), which provides high sensitivity and allows achievement of high resolutions (sub-100 nm). The influence of the e-beam lithography process parameters, namely, exposure dose, development process conditions, and proximity effects on the obtained developed images was studied for the case of 40-keV electron energy.

  1. An integrated system combining chemical looping hydrogen generation process and solid oxide fuel cell/gas turbine cycle for power production with CO2 capture

    Science.gov (United States)

    Chen, Shiyi; Xue, Zhipeng; Wang, Dong; Xiang, Wenguo

    2012-10-01

    In this paper, the solid oxide fuel cell/gas turbine (SOFC/GT) cycle is integrated with coal gasification and chemical looping hydrogen generation (CLHG) for electric power production with CO2 capture. The CLHG-SOFC/GT plant is configurated and the schematic process is modeled using Aspen Plus® software. Syngas, produced by coal gasification, is converted to hydrogen with CO2 separation through a three-reactors CLHG process. Hydrogen is then fueled to SOFC for power generation. The unreacted hydrogen from SOFC burns in a combustor and drives gas turbine. The heat of the gas turbine exhaust stream is recovered in HRSG for steam bottoming cycle. At a system pressure of 20 bar and a cell temperature of 900 °C, the CLHG-SOFC/GT plant has a net power efficiency of 43.53% with no CO2 emissions. The hybrid power plant performance is attractive because of high energy conversion efficiency and zero-CO2-emission. Key parameters that influence the system performance are also discussed, including system operating pressure, cell temperature, fuel utilization factor, steam reactor temperature, CO2 expander exhaust pressure and inlet gas preheating.

  2. Experimental studies of thermal and chemical interactions between molten aluminum and water

    Energy Technology Data Exchange (ETDEWEB)

    Farahani, A.A.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States)

    1995-09-01

    The possibility of rapid physical and chemical aluminum/water interactions during a core melt accident in a noncommercial reactor (e.g., HFIR, ATR) has resulted in extensive research to determine the mechanism by which these interactions occur and propagate on an explosive time scale. These events have been reported in nuclear testing facilities, i.e., during SPERT 1D experiment, and also in aluminum casting industries. Although rapid chemical reactions between molten aluminum and water have been subject of many studies, very few reliable measurements of the extent of the chemical reactions have thus far been made. We have modified an existing 1-D shock tube facility to perform experiments in order to determine the extent of the explosive thermal/chemical interactions between molton aluminum and water by measuring important physical quantities such as the maximum dynamic pressure and the amount of the generated hydrogen. Experimental results show that transient pressures greater than 69 MPa with a rise time of less than 125 {mu}sec can occur as the result of the chemical reaction of 4.2 grams of molton aluminum (approximately 15% of the total mass of the fuel of 28 grams) at 980 C with room temperature water.

  3. Theoretical and experimental investigation of a balanced phase-locked loop based clock recovery at a bit rate of 160 Gb/s

    DEFF Research Database (Denmark)

    Zibar, Darko; Oxenløwe, Leif Katsuo; Clausen, Anders

    2003-01-01

    This paper describes a mathematical model of a balanced opto-electronic phase-locked loop (OPLL), which is required to be very fast for some network applications. OPLL is investigated in terms of clock pulse width, loop filter gain and residuals of the balancing DC level. Based on the guidelines ...

  4. Chemical Looping Combustion with Different Types of Liquid Fuels Combustion en boucle chimique avec différentes charges liquides

    Directory of Open Access Journals (Sweden)

    Hoteit A.

    2011-02-01

    Full Text Available CLC is a new promising combustion process for CO2 capture with less or even no energy penalty compared to other processes. Up to now, most of the work performed on CLC was conducted with gaseous or solid fuels, using methane and coal and/or pet coke. Liquid fuels such as heavy fuels resulting from oil distillation or conversion may also be interesting feedstocks to consider. However, liquid fuels are challenging feedstock to deal with in fluidized beds. The objective of the present work is therefore to investigate the feasibility of liquid feed injection and contact with oxygen carrier in CLC conditions in order to conduct partial or complete combustion of hydrocarbons. A batch experimental fluidized bed set-up was developed to contact alternatively oxygen carrier with liquid fuels or air. The 20 mm i.d. fluidized bed reactor was filled up with 45 g of NiAl0.44O1.67 and pulses of 1-2 g of liquid were injected in the bed at high temperatures up to 950˚C. Different feedstocks have been injected, from dodecane to heavy fuel oils No.2. Results show that, during the reduction period, it is possible to convert all the fuel injected and there is no coke remaining on particles at the end of the reduction step. Depending upon oxygen available in the bed, either full combustion or partial combustion can be achieved. Similar results were found with different liquid feeds, despite their different composition and properties. Le CLC est un nouveau concept prometteur appliqué à la combustion qui permet le captage de CO en minimisant la pénalité énergétique liée au captage. Jusqu’à présent, l’essentiel des travaux de recherche dans le domaine du CLC concerne les charges gazeuses (méthane et solides (charbon et coke. Les charges liquides, et particulièrement les résidus pétroliers, sont des charges également intéressantes à considérer a priori. La mise en oeuvre de ces charges en lit fluidisé est cependant délicate. L’objet de ce

  5. Mechanistic insight into degradation of endocrine disrupting chemical by hydroxyl radical: An experimental and theoretical approach.

    Science.gov (United States)

    Xiao, Ruiyang; Gao, Lingwei; Wei, Zongsu; Spinney, Richard; Luo, Shuang; Wang, Donghong; Dionysiou, Dionysios D; Tang, Chong-Jian; Yang, Weichun

    2017-12-01

    Advanced oxidation processes (AOPs) based on formation of free radicals at ambient temperature and pressure are effective for treating endocrine disrupting chemicals (EDCs) in waters. In this study, we systematically investigated the degradation kinetics of bisphenol A (BPA), a representative EDC by hydroxyl radical (OH) with a combination of experimental and theoretical approaches. The second-order rate constant (k) of BPA with OH was experimentally determined to be 7.2 ± 0.34 × 10 9  M -1  s -1 at pH 7.55. We also calculated the thermodynamic and kinetic behaviors for the bimolecular reactions by density functional theory (DFT) using the M05-2X method with 6-311++G** basis set and solvation model based on density (SMD). The results revealed that H-abstraction on the phenol group is the most favorable pathway for OH. The theoretical k value corrected by the Collins-Kimball approach was determined to be 1.03 × 10 10  M -1  s -1 , which is in reasonable agreement with the experimental observation. These results are of fundamental and practical importance in understanding the chemical interactions between OH and BPA, and aid further AOPs design in treating EDCs during wastewater treatment processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. First experimental observations on melting and chemical modification of volcanic ash during lightning interaction.

    Science.gov (United States)

    Mueller, S P; Helo, C; Keller, F; Taddeucci, J; Castro, J M

    2018-01-23

    Electrification in volcanic ash plumes often leads to syn-eruptive lightning discharges. High temperatures in and around lightning plasma channels have the potential to chemically alter, re-melt, and possibly volatilize ash fragments in the eruption cloud. In this study, we experimentally simulate temperature conditions of volcanic lightning in the laboratory, and systematically investigate the effects of rapid melting on the morphology and chemical composition of ash. Samples of different size and composition are ejected towards an artificially generated electrical arc. Post-experiment ash morphologies include fully melted spheres, partially melted particles, agglomerates, and vesiculated particles. High-speed imaging reveals various processes occurring during the short lightning-ash interactions, such as particle melting and rounding, foaming, and explosive particle fragmentation. Chemical analyses of the flash-melted particles reveal considerable bulk loss of Cl, S, P and Na through thermal vaporization. Element distribution patterns suggest convection as a key process of element transport from the interior of the melt droplet to rim where volatiles are lost. Modeling the degree of sodium loss delivers maximum melt temperatures between 3290 and 3490 K. Our results imply that natural lighting strikes may be an important agent of syn-eruptive morphological and chemical processing of volcanic ash.

  7. Simulations of a Circulating Fluidized Bed Chemical Looping Combustion System Utilizing Gaseous Fuel Simulation de la combustion en boucle chimique d’une charge gazeuse dans un lit fluidisé circulant

    Directory of Open Access Journals (Sweden)

    Mahalatkar K.

    2011-05-01

    Full Text Available Numerical studies using Computational Fluid Dynamics (CFD have been carried out for a complete circulating fluidized bed chemical looping combustor described in the literature (Abad et al., 2006 Fuel 85, 1174-1185. There have been extensive experimental studies in Chemical Looping Combustion (CLC, however CFD simulations of this concept are quite limited. The CLC experiments that were simulated used methane as fuel. A 2-D continuum model was used to describe both the gas and solid phases. Detailed sub-models to account for fluid-particle and particleparticle interaction forces were included. Global models of fuel and carrier chemistry were utilized. The results obtained from CFD were compared with experimental outlet species concentrations, solid circulation rates, solid mass distribution in the reactors, and leakage and dilution rates. The transient CFD simulations provided a reasonable match with the reported experimental data. Des études numériques de simulation des écoulements (CFD ont été réalisées sur un lit fluidisé circulant opérant en combustion par boucle chimique (CLC décrit dans la littérature (Abad et al., 2006 Fuel 85, 1174-1185. Si de nombreuses études expérimentales ont été conduites pour étudier le procédé CLC, les études concernant la simulation des écoulements par CFD de ce concept sont très limitées. Le système de combustion en boucle chimique simulé dans cette étude concerne la combustion d’une charge gazeuse (méthane. Un modèle 2-D à deux phases continues a été utilisé pour décrire les phases gaz et solide avec des sous-modèles détaillés pour décrire les forces d’interactions entre fluideparticule et particule-particule. Des modèles cinétiques globaux ont été intégrés pour décrire les réactions de combustion et de transformation du matériau transporteur d’oxygène. Les résultats obtenus par CFD ont été comparés aux concentrations expérimentales mesurées des diff

  8. Synthesis and Application of Cerium-Incorporated SBA-16 Supported Ni-Based Oxygen Carrier in Cyclic Chemical Looping Steam Methane Reforming

    Directory of Open Access Journals (Sweden)

    Maryam Meshksar

    2018-01-01

    Full Text Available Hydrogen, as a clean energy carrier, could be produced aided by cyclic oxidation-reduction of oxygen carriers (OCs in contact with carbonaceous fuel in chemical looping steam methane reforming (CL-SMR process. In this study, the cerium was incorporated into the SBA-16 support structure to synthesize the Ni/Ce-SBA-16 OC. The supports were synthesized using hydrothermal method followed by impregnation of Ni and characterized via low and wide angle X-ray diffraction (XRD, Brunauer-Emmett-Teller (BET, scanning electron microscopy (SEM, coupled with energy dispersive X-ray (EDX spectroscopy, and transmission electron micrograph (TEM techniques. In addition, the effect of various Si/Ce molar ratios (20–60 in the support structure, Ni loading (10–30 wt %, reaction temperature (500–750 °C, and life time of optimal oxygen carrier over 16 cycles were investigated. The results of wide angle XRD and SEM revealed that the incorporation of CeO2 in the channels of SBA-16 caused the formation of nickel metallic particles with smaller size and prevents the coke formation. The results showed that OC with 15 wt % Ni and Si/Ce molar ratio of 40 (15Ni/Ce-SBA-16(40 has the best performance when compared with other OCs in terms of catalytic activity and structural properties. The methane conversion of about 99.7% was achieved at 700 °C using 15Ni/Ce-SBA-16(40 OC. We anticipate that the strategy can be extended to investigate a variety of novel modified mesoporous silica as the supporting material for the Ni based OCs.

  9. Kinetics of the reduction of hematite (Fe{sub 2}O{sub 3}) by methane (CH{sub 4}) during chemical looping combustion: A global mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Richards, George; Carpenter, Stephen

    2013-10-01

    Chemical-looping combustion (CLC) has emerged as a promising technology for fossil fuel combustion which produces a sequestration ready concentrated CO{sub 2} stream in power production. A CLC system is composed with two reactors, an air and a fuel reactor. An oxygen carrier such as hematite (94%Fe{sub 2}O{sub 3}) circulates between the reactors, which transfers the oxygen necessary for the fuel combustion from the air to the fuel. An important issue for the CLC process is the selection of metal oxide as oxygen carrier, since it must retain its reactivity through many cycles. The primary objective of this work is to develop a global mechanism with respective kinetics rate parameters such that CFD simulations can be performed for large systems. In this study, thermogravimetric analysis (TGA) of the reduction of hematite (Fe{sub 2}O{sub 3}) in a continuous stream of CH{sub 4} (15, 20, and 35%) was conducted at temperatures ranging from 700 to 825{degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2} and H{sub 2}O at the early stage of reaction and H{sub 2} and CO at the final stage of reactions. A kinetic model based on two parallel reactions, 1) first-order irreversible rate kinetics and 2) Avrami equation describing nucleation and growth processes, was applied to the reduction data. It was found, that the reaction rates for both reactions increase with, both, temperature and the methane concentration in inlet gas.

  10. Experimental studies of thermal and chemical interactions between molten aluminum and nuclear dispersion fuels with water

    International Nuclear Information System (INIS)

    Farahani, A.A.

    1997-01-01

    Because of the possibility of rapid physical and chemical molten fuel-water interactions during a core melt accident in noncommercial or experimental reactors, it is important to understand the interactions that might occur if these materials were to contact water. An existing vertical 1-D shock tube facility was improved and a gas sampling device to measure the gaseous hydrogen in the upper chamber of the shock tube was designed and built to study the impact of a water column driven downward by a pressurized gas onto both molten aluminum (6061 alloy) and oxide and silicide depleted nuclear dispersion fuels in aluminum matrices. The experiments were carried out with melt temperatures initially at 750 to 1,000 C and water at room temperature and driving pressures of 0.5 and 1 MPa. Very high transient pressures, in many cases even larger than the thermodynamic critical pressure of the water (∼ 20 MPa), were generated due to the interactions between the water and the crucible and its contents. The molten aluminum always reacted chemically with the water but the reaction did not increase consistently with increasing melt temperature. An aluminum ignition occurred when water at room temperature impacted 28.48 grams of molten aluminum at 980.3 C causing transient pressures greater than 69 MPa. No signs of aluminum ignition were observed in any of the experiments with the depleted nuclear dispersion fuels, U 3 O 8 -Al and U 3 Si 2 -Al. The greater was the molten aluminum-water chemical reaction, the finer was the debris recovered for a given set of initial conditions. Larger coolant velocities (larger driving pressures) resulted in more melt fragmentation but did not result in more molten aluminum-water chemical reaction. Decreasing the water temperature also resulted in more melt fragmentation and did not suppress the molten aluminum-water chemical reaction

  11. Experimental and numerical simulation of the acquisition of chemical remanent magnetization and the Thellier procedure

    Science.gov (United States)

    Shcherbakov, V. P.; Sycheva, N. K.; Gribov, S. K.

    2017-09-01

    The results of the Thellier-Coe experiments on paleointensity determination on the samples which contain chemical remanent magnetization (CRM) created by thermal annealing of titanomagnetites are reported. The results of the experiments are compared with the theoretical notions. For this purpose, Monte Carlo simulation of the process of CRM acquisition in the system of single-domain interacting particles was carried out; the paleointensity determination method based on the Thellier-Coe procedure was modeled; and the degree of paleointensity underestimation was quantitatively estimated based on the experimental data and on the numerical results. Both the experimental investigations and computer modeling suggest the following main conclusion: all the Arai-Nagata diagrams for CRM in the high-temperature area (in some cases up to the Curie temperature T c) contain a relatively long quasi-linear interval on which it is possible to estimate the slope coefficient k and, therefore, the paleointensity. Hence, if chemical magnetization (or remagnetization) took place in the course of the magnetomineralogical transformations of titanomagnetite- bearing igneous rocks during long-lasting cooling or during repeated heatings, it can lead to incorrect results in determining the intensity of the geomagnetic field in the geological past.

  12. Experimental outgassing of toxic chemicals to simulate the characteristics of hazards tainting globally shipped products.

    Directory of Open Access Journals (Sweden)

    Lygia Therese Budnik

    Full Text Available Ambient monitoring analyses may identify potential new public health hazards such as residual levels of fumigants and industrial chemicals off gassing from products and goods shipped globally. We analyzed container air with gas chromatography coupled to mass spectrometry (TD-2D-GC-MS/FPD and assessed whether the concentration of the volatiles benzene and 1,2-dichloroethane exceeded recommended exposure limits (REL. Products were taken from transport containers and analyzed for outgassing of volatiles. Furthermore, experimental outgassing was performed on packaging materials and textiles, to simulate the hazards tainting from globally shipped goods. The mean amounts of benzene in analyzed container air were 698-fold higher, and those of ethylene dichloride were 4.5-fold higher than the corresponding REL. More than 90% of all containers struck with toluene residues higher than its REL. For 1,2-dichloroethane 53% of containers, transporting shoes exceeded the REL. In standardized experimental fumigation of various products, outgassing of 1,2-dichloroethane under controlled laboratory conditions took up to several months. Globally produced transported products tainted with toxic industrial chemicals may contribute to the mixture of volatiles in indoor air as they are likely to emit for a long period. These results need to be taken into account for further evaluation of safety standards applying to workers and consumers.

  13. Tools to prevent process safety events at university research facility - chemical risk assessment and experimental set-up risk assessment

    DEFF Research Database (Denmark)

    Jensen, Niels; Jørgensen, Sten Bay

    2014-01-01

    The article discusses the two forms developed to examine the hazards of the chemicals to be used in the experiments in the experimental setup in the Department of Chemical and Biochemical Engineering of the Technical University of Denmark. A system for the safety assessment of new experimental se...... setups in university research and teaching laboratories is presented. The significance of the forms for the effort of researchers in improving work with significant hazards is described....

  14. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils.

    Science.gov (United States)

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F; Currano, Ellen D; Jacobs, Louis L; Sylvestersen, Rene Lyng; Gabbott, Sarah E; Vinther, Jakob

    2015-10-13

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns.

  15. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

    Science.gov (United States)

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F.; Currano, Ellen D.; Jacobs, Louis L.; Sylvestersen, Rene Lyng; Gabbott, Sarah E.; Vinther, Jakob

    2015-01-01

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns. PMID:26417094

  16. An Experimental and Chemical Kinetics Study of the Combustion of Syngas and High Hydrogen Content Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Santoro, Robers [Pennsylvania State Univ., State College, PA (United States); Dryer, Frederick [Princeton Univ., NJ (United States); Ju, Yiguang [Princeton Univ., NJ (United States)

    2013-09-30

    An integrated and collaborative effort involving experiments and complementary chemical kinetic modeling investigated the effects of significant concentrations of water and CO2 and minor contaminant species (methane [CH4], ethane [C2H6], NOX, etc.) on the ignition and combustion of HHC fuels. The research effort specifically addressed broadening the experimental data base for ignition delay, burning rate, and oxidation kinetics at high pressures, and further refinement of chemical kinetic models so as to develop compositional specifications related to the above major and minor species. The foundation for the chemical kinetic modeling was the well validated mechanism for hydrogen and carbon monoxide developed over the last 25 years by Professor Frederick Dryer and his co-workers at Princeton University. This research furthered advance the understanding needed to develop practical guidelines for realistic composition limits and operating characteristics for HHC fuels. A suite of experiments was utilized that that involved a high-pressure laminar flow reactor, a pressure-release type high-pressure combustion chamber and a high-pressure turbulent flow reactor.

  17. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

    Science.gov (United States)

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F.; Currano, Ellen D.; Jacobs, Louis L.; Lyng Sylvestersen, Rene; Gabbott, Sarah E.; Vinther, Jakob

    2015-10-01

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns.

  18. Experimental and Chemical Kinetic Modeling Study of Dimethylcyclohexane Oxidation and Pyrolysis

    KAUST Repository

    Eldeeb, Mazen A.

    2016-08-30

    A combined experimental and chemical kinetic modeling study of the high-temperature ignition and pyrolysis of 1,3-dimethylcyclohexane (13DMCH) is presented. Ignition delay times are measured behind reflected shock waves over a temperature range of 1049–1544 K and pressures of 3.0–12 atm. Pyrolysis is investigated at average pressures of 4.0 atm at temperatures of 1238, 1302, and 1406 K. By means of mid-infrared direct laser absorption at 3.39 μm, fuel concentration time histories are measured under ignition and pyrolytic conditions. A detailed chemical kinetic model for 13DMCH combustion is developed. Ignition measurements show that the ignition delay times of 13DMCH are longer than those of its isomer, ethylcyclohexane. The proposed chemical kinetic model predicts reasonably well the effects of equivalence ratio and pressure, with overall good agreement between predicted and measured ignition delay times, except at low dilution levels and high pressures. Simulated fuel concentration profiles agree reasonably well with the measured profiles, and both highlight the influence of pyrolysis on the overall ignition kinetics at high temperatures. Sensitivity and reaction pathway analyses provide further insight into the kinetic processes controlling ignition and pyrolysis. The work contributes toward improved understanding and modeling of the oxidation and pyrolysis kinetics of cycloalkanes.

  19. Pilot plant SERSE: Description and results of the experimental tests under treatment of simulated chemical liquid waste

    International Nuclear Information System (INIS)

    Calle, C.; Gili, M.; Luce, A.; Marrocchelli, A.; Pietrelli, L.; Troiani, F.

    1989-11-01

    The chemical processes for the selective separation of the actinides and long lived fission products from aged liquid wastes is described. The SERSE pilot plant is a cold facility which has been designed, by ENEA, for the engineering scale demonstration of the chemical separation processes. The experimental tests carried out in the plant are described and the results confirm the laboratory data. (author)

  20. Chemical Looping with Copper Oxide as Carrier and Coal as Fuel; Boucle chimique pour la combustion du charbon avec un transporteur d'oxygene a base d'oxyde de cuivre

    Energy Technology Data Exchange (ETDEWEB)

    Eyring, E.M.; Konya, G. [Department of Chemistry, Institute for Clean and Secure Energy, University of Utah, Salt Lake City, UT 84112 (United States); Lighty, J.S.; Sahir, A.H.; Sarofim, A.F.; Whitty, K. [Department of Chemical Engineering, Institute for Clean and Secure Energy, University of Utah, Salt Lake City, UT 84112 (United States)

    2011-03-15

    A preliminary analysis has been conducted of the performance of a Chemical Looping system with Oxygen Uncoupling (CLOU) with copper oxide as the oxygen carrier and coal approximated by carbon as the fuel. The advantages of oxygen uncoupling are demonstrated by providing the energy balances, the circulation rate of oxygen carrier, the oxygen carrier mass loadings, the carbon burnout and oxygen partial pressure in the fuel reactor. Experimental data on the cycling of cuprous oxide to cupric oxide and kinetics for the oxidation and decomposition reactions of the oxides were obtained for use in the analysis. For this preliminary study unsupported oxides were utilized. The decomposition temperatures were rapid at the high temperature of 950 C selected for the fuel reactor. The oxidation kinetics peaked at about 800 C with the decrease in rate at higher temperatures, a decrease which is attributed in the literature to the temperature dependence of the diffusional resistance of the CuO layer surrounding the Cu{sub 2}O; the diffusion occurs through grain boundaries in the CuO layers and the rate of diffusion decreases as a consequence of growth of CuO grains with increasing temperature. The analysis shows the advantages of CLOU in providing rapid combustion of the carbon with carbon burnout times lower than the decomposition times of the oxygen carrier. For the full potential of CLOU to be established additional data are needed on the kinetics of supported oxides at the high temperatures ({>=}850 C) at which oxygen is released by the CuO in the fuel reactor. (authors)

  1. Hard-Thermal-Loop QCD thermodynamics and quark number susceptibility

    Directory of Open Access Journals (Sweden)

    Mogliacci Sylvain

    2014-04-01

    Full Text Available The weak-coupling expansion of the QCD pressure is known up to the order g6 log g. However, at experimentally relevant temperatures, the corresponding series is poorly convergent. In this proceedings, we discuss at which extent the gauge-invariant resummation scheme, Hard-Thermal-Loop perturbation theory (HTLpt, improves the apparent convergence. We first present HTLpt results for QCD thermodynamic functions up to three-loop order at vanishing chemical potential. Then, we report a preliminary HTLpt result of one-loop quark number susceptibility, probing the finite density equation of state. Our results are consistent with lattice data down to 2 − 3Tc, reinforcing the weakly-coupled quasiparticle picture in the intermediate coupling regime.

  2. A Novel Chemically Modified Curcumin Reduces Severity of Experimental Periodontal Disease in Rats: Initial Observations

    Directory of Open Access Journals (Sweden)

    Muna S. Elburki

    2014-01-01

    Full Text Available Tetracycline-based matrix metalloproteinase- (MMP- inhibitors are currently approved for two inflammatory diseases, periodontitis and rosacea. The current study addresses the therapeutic potential of a novel pleiotropic MMP-inhibitor not based on an antibiotic. To induce experimental periodontitis, endotoxin (LPS was repeatedly injected into the gingiva of rats on one side of the maxilla; the contralateral (control side received saline injections. Two groups of rats were treated by daily oral intubation with a chemically modified curcumin, CMC 2.24, for two weeks; the control groups received vehicle alone. After sacrifice, gingiva, blood, and maxilla were collected, the jaws were defleshed, and periodontal (alveolar bone loss was quantified morphometrically and by μ-CT scan. The gingivae were pooled per experimental group, extracted, and analyzed for MMPs (gelatin zymography; western blot and for cytokines (e.g., IL-1β; ELISA; serum and plasma samples were analyzed for cytokines and MMP-8. The LPS-induced pathologically excessive bone loss was reduced to normal levels based on either morphometric (P=0.003 or μ-CT (P=0.008 analysis. A similar response was seen for MMPs and cytokines in the gingiva and blood. This initial study, on a novel triketonic zinc-binding CMC, indicates potential efficacy on inflammatory mediators and alveolar bone loss in experimental periodontitis and warrants future therapeutic and pharmacokinetic investigations.

  3. In-pile loop experiments in water chemistry and corrosion

    International Nuclear Information System (INIS)

    Kysela, J.; Jindrich, K.; Masarik, V.; Fric, Z.; Chotivka, V.; Hamerska, H.; Vsolak, R.; Erben, O.

    1986-08-01

    Methods and techniques used were as follows: (a) Method of polarizing resistance for remote monitoring of instantaneous rate of uniform corrosion. (b) Out-of-pile loop at the temperature 350 degC, pressure 19 MPa, circulation 20 kgs/h, testing time 1000 h. (c) High temperature electromagnetic filter with classical solenoid and ball matrix for high pressure filtration tests. (d) High pressure and high temperature in-pile water loop with coolant flow rate 10 000 kgs/h, neutron flux in active channel 7x10 13 n/cm 2 .s, 16 MPa, 330 degC. (e) Evaluation of experimental results by chemical and radiochemical analysis of coolant, corrosion products and corrosion layer on surface. The results of measurements carried out in loop facilities can be summarized into the following conclusions: (a) In-pile and out-of-pile loops are suitable means of investigating corrosion processes and mass transport in the nuclear power plant primary circuit. (b) In studying transport phenomena in the loop, it is necessary to consider the differences in geometry of the loop and the primary circuit, mainly the ratio of irradiated and non-irradiated surfaces and volumes. (c) In the experimental facility simulating the WWER-type nuclear power plant primary circuit, solid suspended particles of a chemical composition corresponding most frequently to magnetite or nickel ferrite, though with non-stoichiometric composition Me x 2+ Fe 3-x 3+ O 4 , were found. (d) Continuous filtration of water by means of an electromagnetic filter removing large particles of corrosion products leads to a decrease in radioactivity of the outer epitactic layer only. The effect of filtration on the inner topotactic layer is negligible

  4. Design of a rotary reactor for chemical-looping combustion. Part 2: Comparison of copper-, nickel-, and iron-based oxygen carriers

    KAUST Repository

    Zhao, Zhenlong

    2014-04-01

    Chemical-looping combustion (CLC) is a novel and promising option for several applications including carbon capture (CC), fuel reforming, H 2 generation, etc. Previous studies demonstrated the feasibility of performing CLC in a novel rotary design with micro-channel structures. Part 1 of this series studied the fundamentals of the reactor design and proposed a comprehensive design procedure, enabling a systematic methodology of designing and evaluating the rotary CLC reactor with different OCs and operating conditions. This paper presents the application of the methodology to the designs with three commonly used OCs, i.e., copper, nickel, and iron. The physical properties and the reactivities of the three OCs are compared at operating conditions suitable for the rotary CLC. Nickel has the highest reduction rate, but relatively slow oxidation reactivity while the iron reduction rate is most sensitive to the fuel concentration. The design parameters and the operating conditions for the three OCs are selected, following the strategies proposed in Part 1, and the performances are evaluated using a one-dimensional plug-flow model developed previously. The simulations show that for all OCs, complete fuel conversion and high carbon separation efficiency can be achieved at periodic stationary state with reasonable operational stabilities. The nickel-based design includes the smallest dimensions because of its fast reduction rate. The operation of nickel case is mainly limited to the slow oxidation rate, and hence a relatively large share of air sector is used. The iron-based design has the largest size, due to its slow reduction reactivity near the exit or in the fuel purge sector where the fuel concentration is low. The gas flow temperature increases monotonically for all the cases, and is mainly determined by the solid temperature. In the periodic state, the local temperature variation is within 40 K and the thermal distortion is limited. The design of the rotary CLC is

  5. Sexual selection and experimental evolution of chemical signals in Drosophila pseudoobscura.

    Science.gov (United States)

    Hunt, J; Snook, R R; Mitchell, C; Crudgington, H S; Moore, A J

    2012-11-01

    Our expectations for the evolution of chemical signals in response to sexual selection are uncertain. How are chemical signals elaborated? Does sexual selection result in complexity of the composition or in altered quantities of expression? We addressed this in Drosophila pseudoobscura by examining male and female cuticular hydrocarbons (CHs) after 82 generations of elevated (E) sexual selection or relaxed sexual selection through monogamy (M). The CH profile consisted of 18 different components. We extracted three eigenvectors using principal component analysis that explained 72% of the variation. principal component (PC)1 described the amount of CHs produced, PC2 the trade-off between short- and long-chain CHs and PC3 the trade-off between apparently arbitrary CHs. In both sexes, the amount of CHs produced was greater in flies from the E treatment. PC3 was also higher, indicating that sexual selection also influenced the evolution of CH composition. The sexes differed in all three PCs, indicating substantial sexual dimorphism in this species, although the magnitude of this dimorphism was not increased as a result of our experimental evolution. Collectively, our work provides direct evidence that sexual selection plays an important role in the evolution of CHs in D. pseudoobscura and that both increased quantity and overall composition are targeted. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

  6. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING; FINAL

    International Nuclear Information System (INIS)

    LICHTENBERGER, DENNIS L.

    2002-01-01

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems

  7. Chemical composition of leaf extracts of Stevia rebaudiana Bertoni grown experimentally in Vojvodina

    Directory of Open Access Journals (Sweden)

    IVANA S. MARKOVIC

    2008-03-01

    Full Text Available The chemical composition of leaf extracts of Stevia rebaudiana Bertoni, grown for the first time on an experimental field near Zrenjanin, was examined by GC–MS. The tested plant material was harvested in September of 2002. To analyze the chemical composition of the lipophilic components of the plant leaves, essential oils and ethyl acetate extract were isolated. Qualitative analysis of the essential oil obtained by hydrodistillation showed that among the identified 88 compounds, the majority were mono- and sesquiterpenes (50 types identified. By analysing the ethyl acetate extract, the presence of fatty acids (present as free and as esters, n-alkanes, n-alkenes, cyclic alkanes, alcohols, aldehydes, ketones, etc. was ascertained. Sesquiterpenes prevailed among the terpenes (50 types identified. Further constituents identified in ethyl acetate extract included sterols. Nerol, b-cyclocitral, safranal, aromadendrene, a-amorphene and T-muurolol were identified for the first time in this species, with match values over 90 %. Taking into consideration that these terpenes were identified for the first time in this species, it is obvious that Stevia rebaudiana grown in this area possesses certain specific characteristics that can be ascribed to cultivation on a domestic plantation.

  8. CHEMICAL ACTIVATION OF MOLECULES BY METALS: EXPERIMENTAL STUDIES OF ELECTRON DISTRIBUTIONS AND BONDING

    Energy Technology Data Exchange (ETDEWEB)

    LICHTENBERGER, DENNIS L.

    2002-03-26

    This research program is directed at obtaining detailed experimental information on the electronic interactions between metals and organic molecules. These interactions provide low energy pathways for many important chemical and catalytic processes. A major feature of the program is the continued development and application of our special high-resolution valence photoelectron spectroscopy (UPS), and high-precision X-ray core photoelectron spectroscopy (XPS) instrumentation for study of organometallic molecules in the gas phase. The study involves a systematic approach towards understanding the interactions and activation of bound carbonyls, C-H bonds, methylenes, vinylidenes, acetylides, alkenes, alkynes, carbenes, carbynes, alkylidenes, alkylidynes, and others with various monometal, dimetal, and cluster metal species. Supporting ligands include -aryls, alkoxides, oxides, and phosphines. We are expanding our studies of both early and late transition metal species and electron-rich and electron-poor environments in order to more completely understand the electronic factors that serve to stabilize particular organic fragments and intermediates on metals. Additional new directions for this program are being taken in ultra-high vacuum surface UPS, XPS, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) experiments on both physisorbed and chemisorbed organometallic thin films. The combination of these methods provides additional electronic structure information on surface-molecule and molecule-molecule interactions. A very important general result emerging from this program is the identification of a close relationship between the ionization energies of the species and the thermodynamics of the chemical and catalytic reactions of these systems.

  9. Experimental Study of Physical and Mechanical Properties of Chemically Grouted Sand and Gravel

    Directory of Open Access Journals (Sweden)

    Hui-Ge Xing

    2014-02-01

    Full Text Available Soil or rock mass with low strength or high permeability may not be appropriate for a dam foundation. Especially the faults are mainly composed by loose sand and gravel, so that they can cause severe damages to overlying structures, because of their considerable distress. Grouting is a suitable improvement technical method to solve this problem. Epoxy resins are commonly used in civil engineering because of their high strength and durability against mechanical or physical erosion. The chemical grouting materials is consisted of resin (component A and hardener (component B. A comprehensive laboratory work was carried out to study the physical and mechanical properties of chemically grouted sand and gravel. Experimental test results show that, the formation of a dense polymer film-sand or film-gravel matrix is resulted in the significant reduction of water permeability and improvement of physical properties. A large number of voids are in filled with epoxy resins which act as adhesive ties to the sand or gravel grains forming a dense impermeable high strength structure. The mechanical properties of sand and gravel are improved by the epoxy resins.

  10. Chemical analysis of interstitial water in rivers of Centro Experimental Aramar area

    Energy Technology Data Exchange (ETDEWEB)

    Matoso, Erika; Goncalves, Julia Rosa, E-mail: ematoso@hotmail.com [Centro Tecnologico da Marinha (CE/CTM-SP), Ipero, SP (Brazil). Centro Experimental Aramar; Cadore, Solange [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Instituto de Quimica. Departamento de Quimica Analitica

    2013-07-01

    This work presents the results from analysis of samples of interstitial waters for the following chemical parameters: F{sup -}, Cl{sup -}, NO{sub 2}{sup -}, Br{sup -}, NO{sub 3}{sup -}, PO{sub 4}{sup 3-}, SO{sub 4}{sup 2-} by Ionic Chromatography, Na, K by Flame Photometry, Al, Cd, Pb, Cu, Cr, Fe, Mn, Ni, Zn by ICP OES, pH and the biological parameter: toxicity by natural bioluminescent bacterium (Vibrio fischeri) bioassay. The samples were obtained from sediments collected in 6 different sampling locations, in a ratio of 10-km-long from Centro Experimental Aramar (CEA). The rivers were the samples came from were: Ipanema River, Sorocaba River and Ribeirao do Ferro River. The interstitial water was extracted by centrifugation (3000 rpm, 20 min, 4 deg C). Analysis for metal concentrations were carried out after acid digestion and others tests proceeded in the sample after filtration without further treatment. These data will contribute to evaluate the distribution of contaminants and nutrients in these collecting points and this toxicity status. The release of soluble substances from sediments to interstitial water provides one way for bioaccumulation of these compounds and may affect the survival or development of aquatic organisms. The analysis in interstitial water has never been evaluated at this sampling points and the importance of this study is collecting data providing a better knowledge of the hydrological conditions in which Centro Experimental Aramar is located. (author)

  11. Energetics and stability of azulene: From experimental thermochemistry to high-level quantum chemical calculations

    International Nuclear Information System (INIS)

    Sousa, Clara C.S.; Matos, M. Agostinha R.; Morais, Victor M.F.

    2014-01-01

    Highlights: • Experimental standard molar enthalpy of formation, sublimation azulene. • Mini-bomb combustion calorimetry, sublimation Calvet microcalorimetry. • High level composite ab initio calculations. • Computational estimate of the enthalpy of formation of azulene. • Discussion of stability and aromaticity of azulene. - Abstract: The standard (p 0 = 0.1 MPa) molar enthalpy of formation for crystalline azulene was derived from the standard molar enthalpy of combustion, in oxygen, at T = 298.15 K, measured in a mini-bomb combustion calorimeter (aneroid isoperibol calorimeter) and the standard molar enthalpy of sublimation, at T = 298.15 K, measured by Calvet microcalorimetry. From these experiments, the standard molar enthalpy of formation of azulene in the gaseous phase at T = 298.15 K was calculated. In addition, very accurate quantum chemical calculations at the G3 and G4 composite levels of calculation were conducted in order to corroborate our experimental findings and further clarify and establish the definitive standard enthalpy of formation of this interesting non-benzenoid hydrocarbon

  12. Experimental and quantum chemical studies of a novel synthetic prenylated chalcone

    Directory of Open Access Journals (Sweden)

    Espinoza-Hicks José C

    2013-01-01

    Full Text Available Abstract Background Chalcones are ubiquitous natural compounds with a wide variety of reported biological activities, including antitumoral, antiviral and antimicrobial effects. Furthermore, chalcones are being studied for its potential use in organic electroluminescent devices; therefore the description of their spectroscopic properties is important to elucidate the structure of these molecules. One of the main techniques available for structure elucidation is the use of Nuclear Magnetic Resonance Spectroscopy (NMR. Accordingly, the prediction of the NMR spectra in this kind of molecules is necessary to gather information about the influence of substituents on their spectra. Results A novel substituted chalcone has been synthetized. In order to identify the functional groups present in the new synthesized compound and confirm its chemical structure, experimental and theoretical 1H-NMR and 13C-NMR spectra were analyzed. The theoretical molecular structure and NMR spectra were calculated at both the Hartree-Fock and Density Functional (meta: TPSS; hybrid: B3LYP and PBE1PBE; hybrid meta GGA: M05-2X and M06-2X levels of theory in combination with a 6-311++G(d,p basis set. The structural parameters showed that the best method for geometry optimization was DFT:M06-2X/6-311++G(d,p, whereas the calculated bond angles and bond distances match experimental values of similar chalcone derivatives. The NMR calculations were carried out using the Gauge-Independent Atomic Orbital (GIAO formalism in a DFT:M06-2X/6-311++G(d,p optimized geometry. Conclusion Considering all HF and DFT methods with GIAO calculations, TPSS and PBE1PBE were the most accurate methods used for calculation of 1H-NMR and 13C-NMR chemical shifts, which was almost similar to the B3LYP functional, followed in order by HF, M05-2X and M06-2X methods. All calculations were done using the Gaussian 09 software package. Theoretical calculations can be used to predict and confirm the structure of

  13. Quantum chemical calculation and experimental measurement of the 13C chemical shift tensors of vanillin and 3,4-dimethoxybenzaldehyde

    Science.gov (United States)

    Zheng, Guang; Hu, Jianzhi; Zhang, Xiaodong; Shen, Lianfang; Ye, Chaohui; Webb, Graham A.

    1997-03-01

    The principal values of the 13C nuclear magnetic resonance chemical shift tensors in vanillin and 3,4-dimethoxybenzaldehyde are reported. Theoretical results of the 13C chemical shift tensors were obtained by employing the gauge included atomic orbital (GIAO) approach. The geometrical parameters were optimized by using the MNDO method. The observed chemical shifts of these two compounds were determined in powders by using the recently introduced magic angle turning (MAT) experiment. The results presented in this paper clearly demonstrate the importance of using tensor information in the study of molecular structures.

  14. Ototoxicity of loop diuretics.

    Science.gov (United States)

    Rybak, L P

    1993-10-01

    The loop diuretics are drugs that increase the excretion of water and electrolytes in the urine by their action on the cells in the loop of Henle. Clinical reports of ototoxicity of these agents are reviewed, and the results of a number of studies in experimental animals are discussed. These drugs can cause either a temporary, or in some cases, a permanent loss of hearing in patients. Animal experiments show that these drugs act on the stria vascularis, producing edema of these tissues and a temporary loss of function, resulting in a decrease of the endocochlear potential. This can result in secondary effects on sound-evoked measures of hearing. As new information unfolds about protective agents, it may be possible to preserve hearing and maintain the desired therapeutic effect.

  15. CaMn0.875Ti0.125O3 as oxygen carrier for chemical-looping combustion with oxygen uncoupling (CLOU)—Experiments in a continuously operating fluidized-bed reactor system

    KAUST Repository

    Rydén, Magnus

    2011-03-01

    Particles of the perovskite material CaMn0.875Ti0.125O3 has been examined as oxygen carrier for chemical-looping with oxygen uncoupling, and for chemical-looping combustion of natural gas, by 70h of experiments in a circulating fluidized-bed reactor system. For the oxygen uncoupling experiments, it was found that the particles released O2 in gas phase at temperatures above 720°C when the fuel reactor was fluidized with CO2. The effect increased with increased temperature, and with the O2 partial pressure in the air reactor. At 950°C, the O2 concentration in the outlet from the fuel reactor was in the order of 4.0vol%, if the particles were oxidized in air. For the chemical-looping combustion experiments the combustion efficiency with standard process parameters was in the order of 95% at 950°C, using 1000kg oxygen carrier per MW natural gas, of which about 30% was located in the fuel reactor. Reducing the fuel flow so that 1900kg oxygen carrier per MW natural gas was used improved the combustion efficiency to roughly 99.8%. The particles retained their physical properties, reactivity with CH4 and ability to release gas-phase O2 reasonably well throughout the testing period and there were no problems with the fluidization or formation of solid carbon in the reactor. X-ray diffraction showed that the particles underwent changes in their phase composition though. © 2010 Elsevier Ltd.

  16. Experimental study of a novel photovoltaic solar-assisted heat pump/loop heat-pipe (PV-SAHP/LHP) system

    Science.gov (United States)

    Zhang, Tao; Pei, Gang; Zhu, Qunzhi; Ji, Jie

    2017-01-01

    A prototype of a photovoltaic solar-assisted heat-pump/loop heat-pipe system (PV-SAHP/LHP) was constructed in this paper. The system was a combination of photovoltaic solar-assisted heat pump system (PV-SAHP) and loop heat pipe photovoltaic/thermal (LHP-PV/T) system. The combined system can carry out with two modes but using the same working fluid, and the two modes can switch operation freely. R600a was employed as the working fluid, and system performance under different working mode was presented in this paper. The results show that the day average photothermal efficiency & photovoltaic efficiency can reach to 43.6% & 11.3% under LHP-PV/T working mode compared with that of 57.5% & 12.1% under PV-SAHP working mode: Besides that, a day average COP of 3.66 was obtained under PV-SAHP working mode.

  17. Characteristics of a foot-and-mouth disease virus with a partial VP1 G-H loop deletion in experimentally infected cattle

    DEFF Research Database (Denmark)

    Fowler, Veronica; Bashiruddin, John B.; Belsham, Graham

    2014-01-01

    Previous work in cattle illustrated the protective efficacy and negative marker potential of a A serotype foot-and-mouth disease virus (FMDV) vaccine prepared from a virus lacking a significant portion of the VP1 G-H loop (termed A(−)). Since this deletion also includes the arginine-glycine-aspar...... be useful as a tool to understand further the natural pathogenesis, receptor usage and internalisation pathways of FMDV....

  18. Experimental investigation on thermal performance of a closed loop pulsating heat pipe (CLPHP) using methanol and distilled water at different filling ratios

    Science.gov (United States)

    Rahman, Md. Lutfor; Swarna, Anindita Dhar; Ahmed, Syed Nasif Uddin; Perven, Sanjida; Ali, Mohammad

    2016-07-01

    Pulsating Heat Pipes, the new two-phase heat transfer devices, with no counter current flow between liquid and vapor have become a modern topic for research in the field of thermal management. This paper focuses on the performance of methanol and distilled water as working fluid in a closed loop pulsating heat pipe (CLPHP). This performances are compared in terms of thermal resistance, heat transfer co-efficient, and evaporator and condenser wall temperature with variable heat inputs. Methanol and Distilled water are selected for their lower surface tension, dynamic viscosity and sensible heat. A closed loop PHP made of copper with 2mm ID and 2.5mm OD having total 8 loops are supplied with power input varied from 10W to 60W. During the experiment the PHP is kept vertical, while the filling ratio (FR) is increased gradually from 40% to 70% with 10% increment. The optimum filling ratio for a minimum thermal resistance is found to be 60% and 40% for distilled water and methanol respectively and methanol is found to be the better working fluid compared to distilled water in terms of its lower thermal resistance and higher heat transfer coefficient.

  19. Use of Modern Chemical Protein Synthesis and Advanced Fluorescent Assay Techniques to Experimentally Validate the Functional Annotation of Microbial Genomes

    Energy Technology Data Exchange (ETDEWEB)

    Kent, Stephen [University of Chicago

    2012-07-20

    The objective of this research program was to prototype methods for the chemical synthesis of predicted protein molecules in annotated microbial genomes. High throughput chemical methods were to be used to make large numbers of predicted proteins and protein domains, based on microbial genome sequences. Microscale chemical synthesis methods for the parallel preparation of peptide-thioester building blocks were developed; these peptide segments are used for the parallel chemical synthesis of proteins and protein domains. Ultimately, it is envisaged that these synthetic molecules would be ‘printed’ in spatially addressable arrays. The unique ability of total synthesis to precision label protein molecules with dyes and with chemical or biochemical ‘tags’ can be used to facilitate novel assay technologies adapted from state-of-the art single molecule fluorescence detection techniques. In the future, in conjunction with modern laboratory automation this integrated set of techniques will enable high throughput experimental validation of the functional annotation of microbial genomes.

  20. Experimental studies of thermal and chemical interactions between oxide and silicide nuclear fuels with water

    Energy Technology Data Exchange (ETDEWEB)

    farahani, A.A.; Corradini, M.L. [Univ. of Wisconsi, Madison, WI (United States)

    1995-09-01

    Given some transient power/cooling mismatch is a nuclear reactor and its inability to establish the necessary core cooling, energetic fuel-coolant interactions (FCI`s commonly called `vapor explosions`) could occur as a result of the core melting and coolant contact. Although a large number of studies have been done on energetic FCI`s, very few experiments have been performed with the actual fuel materials postulated to be produced in severe accidents. Because of the scarcity of well-characterized FCI data for uranium allows in noncommercial reactors (cermet and silicide fuels), we have conducted a series of experiments to provide a data base for the foregoing materials. An existing 1-D shock-tube facility was modified to handle depleted radioactive materials (U{sub 3}O{sub 8}-Al, and U{sub 3}Si{sub 2}-Al). Our objectives have been to determine the effects of the initial fuel composition and temperature and the driving pressure (triggering) on the explosion work output, dynamic pressures, transient temperatures, and the hydrogen production. Experimental results indicate limited energetics, mainly thermal interactions, for these fuel materials as compared to aluminum where more chemical reactions occur between the molten aluminum and water.

  1. Desorption modeling of hydrophobic organic chemicals from plastic sheets using experimentally determined diffusion coefficients in plastics.

    Science.gov (United States)

    Lee, Hwang; Byun, Da-Eun; Kim, Ju Min; Kwon, Jung-Hwan

    2018-01-01

    To evaluate rate of migration from plastic debris, desorption of model hydrophobic organic chemicals (HOCs) from polyethylene (PE)/polypropylene (PP) films to water was measured using PE/PP films homogeneously loaded with the HOCs. The HOCs fractions remaining in the PE/PP films were compared with those predicted using a model characterized by the mass transfer Biot number. The experimental data agreed with the model simulation, indicating that HOCs desorption from plastic particles can generally be described by the model. For hexachlorocyclohexanes with lower plastic-water partition coefficients, desorption was dominated by diffusion in the plastic film, whereas desorption of chlorinated benzenes with higher partition coefficients was determined by diffusion in the aqueous boundary layer. Evaluation of the fraction of HOCs remaining in plastic films with respect to film thickness and desorption time showed that the partition coefficient between plastic and water is the most important parameter influencing the desorption half-life. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  3. In-situ Condition Monitoring of Components in Small Modular Reactors Using Process and Electrical Signature Analysis. Final report, volume 1. Development of experimental flow control loop, data analysis and plant monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyaya, Belle [Univ. of Tennessee, Knoxville, TN (United States); Hines, J. Wesley [Univ. of Tennessee, Knoxville, TN (United States); Damiano, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mehta, Chaitanya [Univ. of Tennessee, Knoxville, TN (United States); Collins, Price [Univ. of Tennessee, Knoxville, TN (United States); Lish, Matthew [Univ. of Tennessee, Knoxville, TN (United States); Cady, Brian [Univ. of Tennessee, Knoxville, TN (United States); Lollar, Victor [Univ. of Tennessee, Knoxville, TN (United States); de Wet, Dane [Univ. of Tennessee, Knoxville, TN (United States); Bayram, Duygu [Univ. of Tennessee, Knoxville, TN (United States)

    2015-12-15

    The research and development under this project was focused on the following three major objectives: Objective 1: Identification of critical in-vessel SMR components for remote monitoring and development of their low-order dynamic models, along with a simulation model of an integral pressurized water reactor (iPWR). Objective 2: Development of an experimental flow control loop with motor-driven valves and pumps, incorporating data acquisition and on-line monitoring interface. Objective 3: Development of stationary and transient signal processing methods for electrical signatures, machinery vibration, and for characterizing process variables for equipment monitoring. This objective includes the development of a data analysis toolbox. The following is a summary of the technical accomplishments under this project: - A detailed literature review of various SMR types and electrical signature analysis of motor-driven systems was completed. A bibliography of literature is provided at the end of this report. Assistance was provided by ORNL in identifying some key references. - A review of literature on pump-motor modeling and digital signal processing methods was performed. - An existing flow control loop was upgraded with new instrumentation, data acquisition hardware and software. The upgrading of the experimental loop included the installation of a new submersible pump driven by a three-phase induction motor. All the sensors were calibrated before full-scale experimental runs were performed. - MATLAB-Simulink model of a three-phase induction motor and pump system was completed. The model was used to simulate normal operation and fault conditions in the motor-pump system, and to identify changes in the electrical signatures. - A simulation model of an integral PWR (iPWR) was updated and the MATLAB-Simulink model was validated for known transients. The pump-motor model was interfaced with the iPWR model for testing the impact of primary flow perturbations (upsets) on

  4. In-situ Condition Monitoring of Components in Small Modular Reactors Using Process and Electrical Signature Analysis. Final report, volume 1. Development of experimental flow control loop, data analysis and plant monitoring

    International Nuclear Information System (INIS)

    Upadhyaya, Belle; Hines, J. Wesley; Damiano, Brian; Mehta, Chaitanya; Collins, Price; Lish, Matthew; Cady, Brian; Lollar, Victor; De Wet, Dane; Bayram, Duygu

    2015-01-01

    The research and development under this project was focused on the following three major objectives: Objective 1: Identification of critical in-vessel SMR components for remote monitoring and development of their low-order dynamic models, along with a simulation model of an integral pressurized water reactor (iPWR). Objective 2: Development of an experimental flow control loop with motor-driven valves and pumps, incorporating data acquisition and on-line monitoring interface. Objective 3: Development of stationary and transient signal processing methods for electrical signatures, machinery vibration, and for characterizing process variables for equipment monitoring. This objective includes the development of a data analysis toolbox. The following is a summary of the technical accomplishments under this project: - A detailed literature review of various SMR types and electrical signature analysis of motor-driven systems was completed. A bibliography of literature is provided at the end of this report. Assistance was provided by ORNL in identifying some key references. - A review of literature on pump-motor modeling and digital signal processing methods was performed. - An existing flow control loop was upgraded with new instrumentation, data acquisition hardware and software. The upgrading of the experimental loop included the installation of a new submersible pump driven by a three-phase induction motor. All the sensors were calibrated before full-scale experimental runs were performed. - MATLAB-Simulink model of a three-phase induction motor and pump system was completed. The model was used to simulate normal operation and fault conditions in the motor-pump system, and to identify changes in the electrical signatures. - A simulation model of an integral PWR (iPWR) was updated and the MATLAB-Simulink model was validated for known transients. The pump-motor model was interfaced with the iPWR model for testing the impact of primary flow perturbations (upsets) on

  5. Mixing and transport during pharmaceutical twin-screw wet granulation: experimental analysis via chemical imaging.

    Science.gov (United States)

    Kumar, Ashish; Vercruysse, Jurgen; Toiviainen, Maunu; Panouillot, Pierre-Emmanuel; Juuti, Mikko; Vanhoorne, Valérie; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar

    2014-07-01

    Twin-screw granulation is a promising continuous alternative for traditional batch high shear wet granulation (HSWG). The extent of HSWG in a twin screw granulator (TSG) is greatly governed by the residence time of the granulation materials in the TSG and degree of mixing. In order to determine the residence time distribution (RTD) and mixing in TSG, mostly visual observation and particle tracking methods are used, which are either inaccurate and difficult for short RTD, or provide an RTD only for a finite number of preferential tracer paths. In this study, near infrared chemical imaging, which is more accurate and provides a complete RTD, was used. The impact of changes in material throughput (10-17 kg/h), screw speed (500-900 rpm), number of kneading discs (2-12) and stagger angle (30-90°) on the RTD and axial mixing of the material was characterised. The experimental RTD curves were used to calculate the mean residence time, mean centred variance and the Péclet number to determine the axial mixing and predominance of convective over dispersive transport. The results showed that screw speed is the most influential parameter in terms of RTD and axial mixing in the TSG and established a significant interaction between screw design parameters (number and stagger angle of kneading discs) and the process parameters (material throughput and number of kneading discs). The results of the study will allow the development and validation of a transport model capable of predicting the RTD and macro-mixing in the TSG. These can later be coupled with a population balance model in order to predict granulation yields in a TSG more accurately. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. On the physical and chemical details of alumina atomic layer deposition: A combined experimental and numerical approach

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Dongqing; Ma, Lulu; Xie, Yuanyuan; Yuan, Chris, E-mail: cyuan@uwm.edu [Department of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 (United States); Jen, Tien Chien [Department of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201 and School of Engineering, University of Alaska Anchorage, Anchorage, Alaska 99508 (United States)

    2015-03-15

    Alumina thin film is typically studied as a model atomic layer deposition (ALD) process due to its high dielectric constant, high thermal stability, and good adhesion on various wafer surfaces. Despite extensive applications of alumina ALD in microelectronics industries, details on the physical and chemical processes are not yet well understood. ALD experiments are not able to shed adequate light on the detailed information regarding the transient ALD process. Most of current numerical approaches lack detailed surface reaction mechanisms, and their results are not well correlated with experimental observations. In this paper, the authors present a combined experimental and numerical study on the details of flow and surface reactions in alumina ALD using trimethylaluminum and water as precursors. Results obtained from experiments and simulations are compared and correlated. By experiments, growth rate on five samples under different deposition conditions is characterized. The deposition rate from numerical simulation agrees well with the experimental results. Details of precursor distributions in a full cycle of ALD are studied numerically to bridge between experimental observations and simulations. The 3D transient numerical model adopts surface reaction kinetics and mechanisms based on atomic-level studies to investigate the surface deposition process. Surface deposition is shown as a strictly self-limited process in our numerical studies. ALD is a complex strong-coupled fluid, thermal and chemical process, which is not only heavily dependent on the chemical kinetics and surface conditions but also on the flow and material distributions.

  7. Experimental investigation of material chemical effects on emergency core cooling pump suction filter performance after loss of coolant accident

    International Nuclear Information System (INIS)

    Park, Jong Woon; Park, Byung Gi; Kim, Chang Hyun

    2009-01-01

    Integral tests of head loss through an emergency core cooling filter screen are conducted, simulating reactor building environmental conditions for 30 days after a loss of coolant accident. A test rig with five individual loops each of whose chamber is established to test chemical product formation and measure the head loss through a sample filter. The screen area at each chamber and the amounts of reactor building materials are scaled down according to specific plant condition. A series of tests have been performed to investigate the effects of calcium-silicate, reactor building spray, existence of calcium-silicate with tri-sodium phosphate (TSP), and composition of materials. The results showed that head loss across the chemical bed with even a small amount of calcium-silicate insulation instantaneously increased as soon as TSP was added to the test solution. Also, the head loss across the filter screen is strongly affected by spray duration and the head loss increase is rapid at the early stage, because of high dissolution and precipitation of aluminum and zinc. After passivation of aluminum and zinc by corrosion, the head loss increase is much slowed down and is mainly induced by materials such as calcium, silicon, and magnesium leached from NUKON TM and concrete. Furthermore, it is newly found that the spay buffer agent, tri-sodium phosphate, to form protective coating on the aluminum surface and reduce aluminum leaching is not effective for a large amount of aluminum and a long spray.

  8. Ideas and Approaches on “Construction of High Level Simulation Experimental Teaching Center of Virtual Chemical Laboratory”

    Science.gov (United States)

    Zhang, Yunshen

    2017-11-01

    With the spiritual guidance of the Circular on the Construction of National Virtual Simulation Experimental Teaching Center by the National Department of Education, according to the requirements of construction task and work content, and based on the reality of the simulation experimental teaching center of virtual chemical laboratory at Tianjin University, this paper mainly strengthens the understanding of virtual simulation experimental teaching center from three aspects, and on this basis, this article puts forward specific construction ideas, which refer to the “four combinations, five in one, the optimization of the resources and school-enterprise cooperation”, and on this basis, this article has made effective explorations. It also shows the powerful functions of the virtual simulation experimental teaching platform in all aspects by taking the synthesis and analysis of organic compounds as an example.

  9. Fuskite® preliminary experimental tests based on permeation against vacuum for hydrogen recovery as a potential application in Pb15.7Li loop systems.

    Energy Technology Data Exchange (ETDEWEB)

    Sacristán, R., E-mail: mrosa.sacristan@sener.es [SENER Ingeniería y Sistemas, C/ Provença 392, 5a, 08025 Barcelona (Spain); Veredas, G. [EURATOM-CIEMAT Fusion Assoc., Fusion Technology Division, Av. Complutense 40, 28040 Madrid (Spain); Bonjoch, I. [SENER Ingeniería y Sistemas, C/ Provença 392, 5a, 08025 Barcelona (Spain); Peñalva, I. [UPV/EHU, Departamento de Ingeniería Nuclear y Mecánica de Fluidos, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Calderón, E. [SENER Ingeniería y Sistemas, C/ Provença 392, 5a, 08025 Barcelona (Spain); Alberro, G. [UPV/EHU, Departamento de Ingeniería Nuclear y Mecánica de Fluidos, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Balart, D. [SENER Ingeniería y Sistemas, Avda. Zugazarte 56, 48930 Las Arenas, Vizcaya (Spain); Sarrionandia-Ibarra, A. [UPV/EHU, Departamento de Ingeniería Nuclear y Mecánica de Fluidos, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Pérez, V. [SENER Ingeniería y Sistemas, Avda. Zugazarte 56, 48930 Las Arenas, Vizcaya (Spain); Ibarra, A. [EURATOM-CIEMAT Fusion Assoc., Fusion Technology Division, Av. Complutense 40, 28040 Madrid (Spain); Legarda, F. [UPV/EHU, Departamento de Ingeniería Nuclear y Mecánica de Fluidos, Alameda de Urquijo s/n, 48013 Bilbao (Spain)

    2014-10-15

    Highlights: • Full material characterization as far as hydrogen transport properties are concern. • Quantification of permeator leaks and material degasification. • Analysis of H{sub 2} recovered by means of permeation against vacuum in different conditions. • Hydrogen recovery efficiencies determination. - Abstract: Tritium recovery in fusion reactors is one of the main goals in R and D, as a limited inventory is available and its uneconomic production. That is the reason why efficient technologies are indispensable to be developed in order to achieve fast tritium recovery and its subsequent reuse in the system for increasing its self-sufficiency. In this work a flexible tritium recovery demonstrator prototype based on permeation against vacuum concept has been designed and manufactured, as well as all necessary equipment for a Pb15.7Li loop implementation in order to test and demonstrate that an in-pipe integrated solution is possible, and at the same time, to validate the manufacturing process. Thus, efficient rates for more optimized future models could be then extrapolated. The aim of this paper is to show the different testing results that have been carried out in this research project. These results include permeation properties of the material considered for the permeator, as long as it has been manufactured with a novel technique, Selective Laser Melting. They also include vacuum tests on the permeator to quantify possible leakages and to set up and analyze the capability to generate vacuum inside the permeator, and finally, permeation tests with the prototype, in a first stage with a gas mixture of hydrogen and argon inside the loop instead of Pb15.7Li.

  10. Differential effects of levodopa and apomorphine on neuronal population oscillations in the cortico-basal ganglia loop circuit in vivo in experimental parkinsonism.

    Science.gov (United States)

    Kühn, Johanna; Haumesser, Jens K; Beck, Maximilian H; Altschüler, Jennifer; Kühn, Andrea A; Nikulin, Vadim V; van Riesen, Christoph

    2017-12-01

    The current pharmacotherapy of Parkinson's disease (PD) is primarily based on two classes of drugs: dopamine precursors, namely levodopa, and dopamine receptor agonists, such as apomorphine. Although both types of agents exert their beneficial clinical effects on motor and non-motor symptoms in PD via dopamine receptors, clinical efficiency and side effects differ substantially between levodopa and apomorphine. Levodopa can provide a greater symptomatic relief than dopamine receptor agonists. However, because long-term levodopa use is associated with early debilitating motor fluctuations, dopamine receptor agonists are often recommended in younger patients. The pharmacodynamic basis of these profound differences is incompletely understood. It has been hypothesized that levodopa and dopamine receptor agonists may have diverging effects on beta and gamma oscillations that have been shown to be of importance for the pathophysiology of PD. Here, we used electrophysiological recordings in anesthetized dopamine-intact and dopamine-depleted rats to systemically compare the impact of levodopa or apomorphine on neuronal population oscillations in three nodes of the cortico-basal ganglia loop circuit. Our results showed that levodopa had a higher potency than apomorphine to suppress the abnormal beta oscillations often associated with bradykinesia while simultaneously enhancing the gamma oscillations often associated with increased movement. Our data suggests that the higher clinical efficacy of levodopa as well as some of its side effects, as e.g. dyskinesias may be based on its characteristic ability to modulate beta-/gamma-oscillation dynamics in the cortico-basal ganglia loop circuit. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Loop Transfer Matrix and Loop Quantum Mechanics

    International Nuclear Information System (INIS)

    Savvidy, George K.

    2000-01-01

    The gonihedric model of random surfaces on a 3d Euclidean lattice has equivalent representation in terms of transfer matrix K(Q i ,Q f ), which describes the propagation of loops Q. We extend the previous construction of the loop transfer matrix to the case of nonzero self-intersection coupling constant κ. We introduce the loop generalization of Fourier transformation which allows to diagonalize transfer matrices, that depend on symmetric difference of loops only and express all eigenvalues of 3d loop transfer matrix through the correlation functions of the corresponding 2d statistical system. The loop Fourier transformation allows to carry out the analogy with quantum mechanics of point particles, to introduce conjugate loop momentum P and to define loop quantum mechanics. We also consider transfer matrix on 4d lattice which describes propagation of memebranes. This transfer matrix can also be diagonalized by using the generalized Fourier transformation, and all its eigenvalues are equal to the correlation functions of the corresponding 3d statistical system. In particular the free energy of the 4d membrane system is equal to the free energy of 3d gonihedric system of loops and is equal to the free energy of 2d Ising model. (author)

  12. Tritium Management Loop Design Status

    Energy Technology Data Exchange (ETDEWEB)

    Rader, Jordan D. [ORNL; Felde, David K. [ORNL; McFarlane, Joanna [ORNL; Greenwood, Michael Scott [ORNL; Qualls, A L. [ORNL; Calderoni, Pattrick [Idaho National Laboratory (INL)

    2017-12-01

    This report summarizes physical, chemical, and engineering analyses that have been done to support the development of a test loop to study tritium migration in 2LiF-BeF2 salts. The loop will operate under turbulent flow and a schematic of the apparatus has been used to develop a model in Mathcad to suggest flow parameters that should be targeted in loop operation. The introduction of tritium into the loop has been discussed as well as various means to capture or divert the tritium from egress through a test assembly. Permeation was calculated starting with a Modelica model for a transport through a nickel window into a vacuum, and modifying it for a FLiBe system with an argon sweep gas on the downstream side of the permeation interface. Results suggest that tritium removal with a simple tubular permeation device will occur readily. Although this system is idealized, it suggests that rapid measurement capability in the loop may be necessary to study and understand tritium removal from the system.

  13. Chemical Looping with Copper Oxide as Carrier and Coal as Fuel Boucle chimique pour la combustion du charbon avec un transporteur d’oxygène à base d’oxyde de cuivre

    Directory of Open Access Journals (Sweden)

    Eyring E.M.

    2011-04-01

    Full Text Available A preliminary analysis has been conducted of the performance of a Chemical Looping system with Oxygen Uncoupling (CLOU with copper oxide as the oxygen carrier and coal approximated by carbon as the fuel. The advantages of oxygen uncoupling are demonstrated by providing the energy balances, the circulation rate of oxygen carrier, the oxygen carrier mass loadings, the carbon burnout and oxygen partial pressure in the fuel reactor. Experimental data on the cycling of cuprous oxide to cupric oxide and kinetics for the oxidation and decomposition reactions of the oxides were obtained for use in the analysis. For this preliminary study unsupported oxides were utilized. The decomposition temperatures were rapid at the high temperature of 950°C selected for the fuel reactor. The oxidation kinetics peaked at about 800°C with the decrease in rate at higher temperatures, a decrease which is attributed in the literature to the temperature dependence of the diffusional resistance of the CuO layer surrounding the Cu2O; the diffusion occurs through grain boundaries in the CuO layers and the rate of diffusion decreases as a consequence of growth of CuO grains with increasing temperature. The analysis shows the advantages of CLOU in providing rapid combustion of the carbon with carbon burnout times lower than the decomposition times of the oxygen carrier. For the full potential of CLOU to be established additional data are needed on the kinetics of supported oxides at the high temperatures (>850°C at which oxygen is released by the CuO in the fuel reactor. Une analyse préliminaire a été conduite pour estimer les performances d’un procédé en boucle chimique découplé (CLOU, chemical looping uncoupling pour la combustion du charbon avec un transporteur d’oxygène à base d’oxyde de cuivre. Les avantages de ce système sont démontrés en établissant le bilan énergétique, l’inventaire et le débit de circulation du matériau transportant l

  14. Chemical-looping combustion of coal usin ilmenite as oxygen-carrier (Combustión de carbón con captura de CO2 usando ilmenita como transportador de oxigeno)

    OpenAIRE

    Cuadrat Fernández, Ana; Adánez Elorza, Juan; Abad Secades, Alberto

    2012-01-01

    La combustión con transportadores sólidos de oxígeno o Chemical-Looping Combustion, (CLC) es una tecnología de combustión con captura inherente del gas de efecto invernadero CO2. Debido al bajo coste de captura de CO2 que posee es una tecnología prometedora para centrales térmicas de combustibles fósiles. En CLC el oxígeno del aire se transfiere al combustible con un transportador sólido de oxígeno que circula entre dos reactores de lecho fluidizado: el reactor de reducción y el de oxidación....

  15. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  16. Thermodynamic Possibilities and Constraints for Pure Hydrogen Production by a Nickel and Cobalt-Based Chemical Looping Process at Lower Temperatures

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Karel; Siewiorek, A.; Baxter, D.; Rogut, J.; Pohořelý, Michael

    2008-01-01

    Roč. 49, č. 2 (2008), s. 221-231 ISSN 0196-8904 Institutional research plan: CEZ:AV0Z40720504 Keywords : hydrogen * nickel * cobalt Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.813, year: 2008

  17. Thermodynamic Possibilities and Constraints of Pure Hydrogen Production by a Chromium, Nickel and Manganese-Based Chemical Looping Process at Lower Temperatures

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Karel; Siewiorek, A.; Baxter, D.; Rogut, J.; Punčochář, Miroslav

    2007-01-01

    Roč. 61, č. 2 (2007), s. 110-120 ISSN 0366-6352 Institutional research plan: CEZ:AV0Z40720504 Keywords : chromium * thermodynamics * hydrogen Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.367, year: 2007

  18. Using highly efficient nonlinear experimental design methods for optimization of Lactococcus lactis fermentation in chemically defined media.

    Science.gov (United States)

    Zhang, Guiying; Block, David E

    2009-01-01

    Optimization of fermentation media and processes is a difficult task due to the potential for high dimensionality and nonlinearity. Here we develop and evaluate variations on two novel and highly efficient methods for experimental fermentation optimization. The first approach is based on using a truncated genetic algorithm with a developing neural network model to choose the best experiments to run. The second approach uses information theory, along with Bayesian regularized neural network models, for experiment selection. To evaluate these methods experimentally, we used them to develop a new chemically defined medium for Lactococcus lactis IL1403, along with an optimal temperature and initial pH, to achieve maximum cell growth. The media consisted of 19 defined components or groups of components. The optimization results show that the maximum cell growth from the optimal process of each novel method is generally comparable to or higher than that achieved using a traditional statistical experimental design method, but these optima are reached in about half of the experiments (73-94 vs. 161, depending on the variants of methods). The optimal chemically defined media developed in this work are rich media that can support high cell density growth 3.5-4 times higher than the best reported synthetic medium and 72% higher than a commonly used complex medium (M17) at optimization scale. The best chemically defined medium found using the method was evaluated and compared with other defined or complex media at flask- and fermentor-scales. (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009.

  19. How prevalent is chemical hormesis in the natural and experimental worlds?

    International Nuclear Information System (INIS)

    Mushak, Paul

    2013-01-01

    Hormesis is described as a biological phenomenon showing bidirectional (biphasic) responses to chemical or other stressors: stimulation at low doses and inhibition at high doses or vice-versa. The label applies to either radiation or chemical hormesis. This review addresses certain critical but persisting quantitative questions about chemical hormesis. For example, what is its actual generalizability in nature? Is hormesis generalizable enough to figure in risk analysis and regulatory efforts within human or ecological toxicant exposures? No evidence exists to show that chemical hormesis is a universally distributed biological phenomenon within some law, rule or principle (100% frequency) nor is there a reliable and consistent body of evidence that leads to identifying some significant and reproducible value for frequency of occurrence below the universality standard, i.e., < 100% frequency. Lack of reliable and/or consistent evidence arises from diverse limits to study methods, i.e., methods were post-hoc evaluations of published data gathered for other purposes and using ad-hoc characterization approaches, rather than doing new studies. The literature selected for generalizability analyses has not been systematically pre-evaluated as a scientifically reliable representation of hormesis frequency in nature. Furthermore, database evaluations have used certain criteria not validated for this specific purpose, so that metric and what was measured are objects of scrutiny and ambiguity. Finally, simultaneous estimates of frequency of non-hormetic dose–response relationships, required for reliable determinations of hormesis frequency, were not done in these analyses. Chemical hormesis frequency estimates vary with conditions for characterization. For all these reasons, chemical hormesis still has limited use in health policy and regulatory thinking. - Highlights: ► Hormesis is not a universally distributed biological phenomenon (100% frequency). ► There is also no

  20. How prevalent is chemical hormesis in the natural and experimental worlds?

    Energy Technology Data Exchange (ETDEWEB)

    Mushak, Paul, E-mail: pandbmushak@cs.com

    2013-01-15

    Hormesis is described as a biological phenomenon showing bidirectional (biphasic) responses to chemical or other stressors: stimulation at low doses and inhibition at high doses or vice-versa. The label applies to either radiation or chemical hormesis. This review addresses certain critical but persisting quantitative questions about chemical hormesis. For example, what is its actual generalizability in nature? Is hormesis generalizable enough to figure in risk analysis and regulatory efforts within human or ecological toxicant exposures? No evidence exists to show that chemical hormesis is a universally distributed biological phenomenon within some law, rule or principle (100% frequency) nor is there a reliable and consistent body of evidence that leads to identifying some significant and reproducible value for frequency of occurrence below the universality standard, i.e., < 100% frequency. Lack of reliable and/or consistent evidence arises from diverse limits to study methods, i.e., methods were post-hoc evaluations of published data gathered for other purposes and using ad-hoc characterization approaches, rather than doing new studies. The literature selected for generalizability analyses has not been systematically pre-evaluated as a scientifically reliable representation of hormesis frequency in nature. Furthermore, database evaluations have used certain criteria not validated for this specific purpose, so that metric and what was measured are objects of scrutiny and ambiguity. Finally, simultaneous estimates of frequency of non-hormetic dose–response relationships, required for reliable determinations of hormesis frequency, were not done in these analyses. Chemical hormesis frequency estimates vary with conditions for characterization. For all these reasons, chemical hormesis still has limited use in health policy and regulatory thinking. - Highlights: ► Hormesis is not a universally distributed biological phenomenon (100% frequency). ► There is also no

  1. Chemical Looping Combustion of Solid Fuels in a 10 kWth Unit Combustion de charge solide en boucle chimique dans une unité de 10 kWth

    Directory of Open Access Journals (Sweden)

    Berguerand N.

    2011-02-01

    Full Text Available The present study is based on previous results from batch experiments which were conducted in a 10 kWth chemical looping combustor for solid fuels using ilmenite, an iron titanium oxide, as the oxygen carrier with two solid fuels: a Mexican petroleum coke and a South African bituminous coal. These experiments involved testing at different fuel reactor temperatures, up to 1030°C, and different particle circulation rates between the air and fuel reactors. Previous results enabled modeling of the reactor system. In particular, it was possible to derive a correlation between measured operational data and actual circulation mass flow, as well as a model that describes the carbon capture efficiency as a function of the residence time and the char reactivity. Moreover, the kinetics of char conversion could be modeled and results showed good agreement with experimental values. The purpose of the present study was to complete these results by developing a model to predict the conversion of syngas with ilmenite in the fuel reactor. Here, kinetic data from investigations of ilmenite in TGA and batch fluidized bed reactors were used. Results were compared with the actual conversions during operation in this 10 kWth unit. Cette étude est basée sur des résultats antérieurs obtenus dans une unité de combustion de charges solides en boucle chimique d’une puissance de 10 kWth. Le transporteur d’oxygène utilisé est de l’ilménite, un minerai de fer et de titane, et les charges solides étudiées sont, d’une part, un coke de pétrole mexicain et, d’autre part, un charbon bitumineux sud africain. Les résultats expérimentaux ont été obtenus à des températures allant jusqu’à 1030°C avec différents débits de transporteur d’oxygène entre les réacteurs d’oxydation et de réduction. La modélisation de la combustion en boucle chimique de charges solides a déjà permis d’établir une corrélation entre le débit de circulation de

  2. Rapid and Sensitive Detection of Bartonella bacilliformis in Experimentally Infected Sand Flies by Loop-Mediated Isothermal Amplification (LAMP) of the Pap31 Gene

    Science.gov (United States)

    Angkasekwinai, Nasikarn; Atkins, Erin H.; Johnson, Richard N.; Grieco, John P.; Ching, Wei Mei; Chao, Chien Chung

    2014-01-01

    Background Carrion' disease, caused by Bartonella bacilliformis, remains truly neglected due to its focal geographical nature. A wide spectrum of clinical manifestations, including asymptomatic bacteremia, and lack of a sensitive diagnostic test can potentially lead to a spread of the disease into non-endemic regions where competent sand fly vectors may be present. A reliable test capable of detecting B. bacilliformis is urgently needed. Our objective is to develop a loop-mediated isothermal amplification (LAMP) assay targeting the pap31 gene to detect B. bacilliformis. Methods and Findings The sensitivity of the LAMP was evaluated in comparison to qPCR using plasmid DNA containing the target gene and genomic DNA in the absence and presence of human or sand fly DNA. The detection limit of LAMP was 1 to 10 copies/µL, depending on the sample metrics. No cross-reaction was observed when testing against a panel of various closely related bacteria. The utility of the LAMP was further compared to qPCR by the examination of 74 Lutzomyia longipalpis sand flies artificially fed on blood spiked with B. bacilliformis and harvested at days (D) 1, 3, 5, 7 and 9 post feeding. Only 86% of sand flies at D1 and 63% of flies at D3 were positive by qPCR. LAMP was able to detect B. bacilliformis in all those flies confirmed positive by qPCR. However, none of the flies after D3 were positive by either LAMP or qPCR. In addition to demonstrating the sensitivity of the LAMP assay, these results suggest that B. bacilliformis cannot propagate in artificially fed L. longipalpis. Conclusions The LAMP assay is as sensitive as qPCR for the detection of B. bacilliformis and could be useful to support diagnosis of patients in low-resource settings and also to identify B. bacilliformis in the sand fly vector. PMID:25522230

  3. Rapid and sensitive detection of Bartonella bacilliformis in experimentally infected sand flies by loop-mediated isothermal amplification (LAMP of the Pap31 gene.

    Directory of Open Access Journals (Sweden)

    Nasikarn Angkasekwinai

    2014-12-01

    Full Text Available Carrion' disease, caused by Bartonella bacilliformis, remains truly neglected due to its focal geographical nature. A wide spectrum of clinical manifestations, including asymptomatic bacteremia, and lack of a sensitive diagnostic test can potentially lead to a spread of the disease into non-endemic regions where competent sand fly vectors may be present. A reliable test capable of detecting B. bacilliformis is urgently needed. Our objective is to develop a loop-mediated isothermal amplification (LAMP assay targeting the pap31 gene to detect B. bacilliformis.The sensitivity of the LAMP was evaluated in comparison to qPCR using plasmid DNA containing the target gene and genomic DNA in the absence and presence of human or sand fly DNA. The detection limit of LAMP was 1 to 10 copies/µL, depending on the sample metrics. No cross-reaction was observed when testing against a panel of various closely related bacteria. The utility of the LAMP was further compared to qPCR by the examination of 74 Lutzomyia longipalpis sand flies artificially fed on blood spiked with B. bacilliformis and harvested at days (D 1, 3, 5, 7 and 9 post feeding. Only 86% of sand flies at D1 and 63% of flies at D3 were positive by qPCR. LAMP was able to detect B. bacilliformis in all those flies confirmed positive by qPCR. However, none of the flies after D3 were positive by either LAMP or qPCR. In addition to demonstrating the sensitivity of the LAMP assay, these results suggest that B. bacilliformis cannot propagate in artificially fed L. longipalpis.The LAMP assay is as sensitive as qPCR for the detection of B. bacilliformis and could be useful to support diagnosis of patients in low-resource settings and also to identify B. bacilliformis in the sand fly vector.

  4. Experimental Investigation of Electro-chemical Processes Controlled by High Magnetic Fields.

    Czech Academy of Sciences Publication Activity Database

    Mathon, Ph.; Nouri, A.; Alemany, A.; Chopart, J.P.; Sobolík, Václav

    2006-01-01

    Roč. 42, 4 (2006) , s. 363-369 ISSN 0024-998X Institutional research plan: CEZ:AV0Z40720504 Keywords : lorentz and magnetic force * diffusion-controlled regime * electrical current Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  5. Experimental study on the influence of chemical sensitizer on pressure resistance in deep water of emulsion explosives

    Science.gov (United States)

    Liu, Lei; zhang, Zhihua; Wang, Ya; Qin, hao

    2018-03-01

    The study on the pressure resistance performance of emulsion explosives in deep water can provide theoretical basis for underwater blasting, deep-hole blasting and emulsion explosives development. The sensitizer is an important component of emulsion explosives. By using reusable experimental devices to simulate the charge environment in deep water, the influence of the content of chemical sensitizer on the deep-water pressure resistance performance of emulsion explosives was studied. The experimental results show that with the increasing of the content of chemical sensitizer, the deep-water pressure resistance performance of emulsion explosives gradually improves, and when the pressure is fairly large, the effect is particularly pronounced; in a certain range, with the increase of the content of chemical sensitizer, that emulsion explosives’ explosion performance also gradually improve, but when the content reaches a certain value, the explosion properties declined instead; under the same emulsion matrix condition, when the content of NANO2 is 0.2%, that the emulsion explosives has good resistance to water pressure and good explosion properties. The correctness of the results above was testified in model blasting.

  6. Uranyl Nitrate Flow Loop

    International Nuclear Information System (INIS)

    Ladd-Lively, Jennifer L

    2008-01-01

    The objectives of the work discussed in this report were to: (1) develop a flow loop that would simulate the purified uranium-bearing aqueous stream exiting the solvent extraction process in a natural uranium conversion plant (NUCP); (2) develop a test plan that would simulate normal operation and disturbances that could be anticipated in an NUCP; (3) use the flow loop to test commercially available flowmeters for use as safeguards monitors; and (4) recommend a flowmeter for production-scale testing at an NUCP. There has been interest in safeguarding conversion plants because the intermediate products [uranium dioxide (UO 2 ), uranium tetrafluoride (UF 4 ), and uranium hexafluoride (UF 6 )] are all suitable uranium feedstocks for producing special nuclear materials. Furthermore, if safeguards are not applied virtually any nuclear weapons program can obtain these feedstocks without detection by the International Atomic Energy Agency (IAEA). Historically, IAEA had not implemented safeguards until the purified UF 6 product was declared as feedstock for enrichment plants. H. A. Elayat et al. provide a basic definition of a safeguards system: 'The function of a safeguards system on a chemical conversion plant is in general terms to verify that no useful nuclear material is being diverted to use in a nuclear weapons program'. The IAEA now considers all highly purified uranium compounds as candidates for safeguarding. DOE is currently interested in 'developing instruments, tools, strategies, and methods that could be of use to the IAEA in the application of safeguards' for materials found in the front end of the nuclear fuel cycle-prior to the production of the uranium hexafluoride or oxides that have been the traditional starting point for IAEA safeguards. Several national laboratories, including Oak Ridge, Los Alamos, Lawrence Livermore, and Brookhaven, have been involved in developing tools or techniques for safeguarding conversion plants. This study was sponsored by

  7. Design configurations of the methanol synthesis loop

    OpenAIRE

    Bøhn, Kristian

    2011-01-01

    In recent years the chemical industry has undergone considerable changes due to increased environmental regulations and energy costs. This master thesis has evaluated three different design considerations of the methanol synthesis loop using Honeywell's general purpose process simulator UniSim Design (R380 Build 14027) combined with MathWorks programming language MATLAB. The three configurations are Lurgis methanol reactor loop as built on Tjeldbergodden, the use of interstage methanol remova...

  8. Experimental plant for the physical-chemical treatment of groundwater polluted by Municipal Solid Waste (MSW leachate, with ammonia recovery

    Directory of Open Access Journals (Sweden)

    Massimo Raboni

    2013-12-01

    Full Text Available The paper documents the results of the experimental treatment of groundwater (flow rate: 300 m3 h-1 polluted by the leachate of an old MSW landfill (7 million tonnes in northern Italy. The process consists of a coagulation-flocculation pre-treatment at pH > 11, and subsequent ammonia stripping, after heating the water to 35-38 °C by means of the biogas produced by the landfill. The stripped ammonia was recovered by absorption with sulfuric acid, producing a 30% solution of ammonium sulfate, which was reused as a base fertilizer. In addition, the paper reports important operational aspects related to the scaling of the stripping tower’s packing and its effect on pH and temperature profiles inside the towers caused by the closed loop, which recirculates the stripping air coming from the ammonia absorption towers with sulfuric acid. The average removal efficiency of ammonia reached 95.4% with an inlet mean concentration of 199.0 mg L-1.

  9. Man-made chemicals found in remote areas of the world: the experimental definition for POPs.

    Science.gov (United States)

    Ballschmite, Karlheinz; Hackenberg, Rudolf; Jarman, Walter M; Looser, Ralf

    2002-01-01

    Members of the United Nations Economic Commission for Europe (UN-ECE) signed a legally binding protocol on persistent organic pollutants (POPs) in February 1998 under the Convention on Long-Range Transboundary Air Pollution. A treaty that intends to control the production, import, export, disposal and use of toxic chemicals that persist for decades in the environment has been formally signed at a conference in May 2001 in Stockholm. The 2001 POP treaty, like the 1998 LRTAP POP protocol, contains a provision on adding further chemicals to the initial group of twelve or fifteen. The occurrence of a compound or a group of compounds in so called remote and pristine areas, e.g. in the Artic or in the Southern Hemisphere, proves its stability under the chemical and biological conditions of the environment. Compounds identified in this way, in samples taken primarily in very remote regions of the planet, are classified by their environmental fate and global distribution as persistent organic pollutants (POPs), regardless of any political assessments.

  10. [Evaluation of the hazard of soil-polluting chemicals upon exposure of experimental animals].

    Science.gov (United States)

    Rusakov, N V; Mukhambetova, L Kh; Kriatov, I A; Koganova, Z I; Fadeeva, I I; Chudakova, S B; Evseeva, I S; Solntseva, n V

    2007-01-01

    The experimental study of the biological activity of the modified calcium chloride produced by a Volgograd plant and that of ash-and-slag of the pharmaceuticals resulting after combustion of a pyrolytic mixture of filtration burning could establish various hazards of these substances.

  11. Evaluation of system codes for analyzing naturally circulating gas loop

    International Nuclear Information System (INIS)

    Lee, Jeong Ik; No, Hee Cheon; Hejzlar, Pavel

    2009-01-01

    Steady-state natural circulation data obtained in a 7 m-tall experimental loop with carbon dioxide and nitrogen are presented in this paper. The loop was originally designed to encompass operating range of a prototype gas-cooled fast reactor passive decay heat removal system, but the results and conclusions are applicable to any natural circulation loop operating in regimes having buoyancy and acceleration parameters within the ranges validated in this loop. Natural circulation steady-state data are compared to numerical predictions by two system analysis codes: GAMMA and RELAP5-3D. GAMMA is a computational tool for predicting various transients which can potentially occur in a gas-cooled reactor. The code has a capability of analyzing multi-dimensional multi-component mixtures and includes models for friction, heat transfer, chemical reaction, and multi-component molecular diffusion. Natural circulation data with two gases show that the loop operates in the deteriorated turbulent heat transfer (DTHT) regime which exhibits substantially reduced heat transfer coefficients compared to the forced turbulent flow. The GAMMA code with an original heat transfer package predicted conservative results in terms of peak wall temperature. However, the estimated peak location did not successfully match the data. Even though GAMMA's original heat transfer package included mixed-convection regime, which is a part of the DTHT regime, the results showed that the original heat transfer package could not reproduce the data with sufficient accuracy. After implementing a recently developed correlation and corresponding heat transfer regime map into GAMMA to cover the whole range of the DTHT regime, we obtained better agreement with the data. RELAP5-3D results are discussed in parallel.

  12. Evolution of the quaternary magmatic system, Mineral Mountains, Utah: Interpretations from chemical and experimental modeling

    Energy Technology Data Exchange (ETDEWEB)

    Nash, W.P.; Crecraft, H.R.

    1982-09-01

    The evolution of silicic magmas in the upper crust is characterized by the establishment of chemical and thermal gradients in the upper portion of magma chambers. The chemical changes observed in rhyolite magmas erupted over a period of 300,000 years in the Mineral Mountains are similar to those recorded at Twin Peaks, Utah, and in the spatially zoned Bishop Tuff from Long Valley, California. Chemical and fluid dynamic models indicate that cooling of a silicic magma body from the top and sides can result in the formation of a roof zone above a convecting region which is chemically and thermally stratified, as well as highly fractionated and water rich. Crystallization experiments have been performed with sodium carbonate solutions as an analog to crystallization in magmatic systems. Top and side cooling of a homogeneous sodium carbonate solution results in crystallization along the top and sides and upward convection of sodium carbonate-depleted fluid. A stably stratified roof zone, which is increasingly water rich and cooler upwards, develops over a thermally and chemically homogeneous convecting region. Crystallization at the top ultimately ceases, and continued upward convection of water-rich fluid causes a slight undersaturation adjacent to the roof despite cooler temperatures. By analogy, crystallization at the margins of a magma chamber and buoyant rise of the fractionated boundary layer into the roof zone can account for the chemical evolution of the magma system at the Mineral Mountains. To produce compositionally stratified silicic magmas requires thermal input to a silicic system via mafic magmas. The small volume, phenocryst-poor rhyolite magma which persisted for at least 300,000 years in the Mineral Mountains requires the presence of a continued thermal input from a mafic magma source. The presence of silicic lavas signifies that there is a substantial thermal anomaly both in the crust and upper mantle. The production of silicic lavas requires (1) the

  13. Development of test stand for experimental investigation of chemical and physical phenomena in Liquid Rocket Engine

    Directory of Open Access Journals (Sweden)

    Emerson Andrade Santos

    2011-05-01

    Full Text Available The main objective of this work was to present the specification of an experimental firing test stand for liquid rocket engines (LRE and develop a program for control and acquisition of data. It provides conditions to test rocket engines with thrust from 50 to 100 kgf. A methodology for laboratory work implementation using information technology, which will allow the automatic and remote functioning of the test stand, permits users to input the necessary data to conduct tests safely, achieve accurate measurements and obtain reliable results. The control of propellant mass flow rates by pressure regulators and other system valves, as well as the test stand data acquisition, are carried out automatically through LabVIEW commercial software. The test stand program is a readable, scalable and maintainable code. The test stand design and its development represent the state of art of experimental apparatus in LRE testing.

  14. Effect of Sechium edule on chemical induced kidney damage in experimental animals

    Directory of Open Access Journals (Sweden)

    Sayeed Mohammed Firdous Mumtaz

    2013-03-01

    Full Text Available The aqueous extract of leaves of Sechium edule was evaluated for its protective activity against gentamicin, potassium dichromate-induced nephrotoxicity and streptozotocin-induced diabetic nephropathy in experimental animals. In these three conditions, the extract of S. edule (200 mg/kg has significantly (p<0.001 decreased the level of blood urea, blood urea nitrogen and serum creatinine and also significantly (p<0.001 increased the serum levels of total protein. The serum uric acid level was also significantly (p<0.001 decrease in diabetic mice treated with the extract (200 mg/kg. The extract also improves the histology of the kidney. The results indicate that aqueous extract of leaves of S. edule has possessed protective effect against gentamicin- and potassium dichromate-induced nephrotoxicity and streptozotocin-induced diabetic nephropathy in experimental animals.

  15. Model-based experimental design for assessing effects of mixtures of chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Baas, Jan, E-mail: jan.baas@falw.vu.n [Vrije Universiteit of Amsterdam, Dept of Theoretical Biology, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands); Stefanowicz, Anna M., E-mail: anna.stefanowicz@uj.edu.p [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Klimek, Beata, E-mail: beata.klimek@uj.edu.p [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Laskowski, Ryszard, E-mail: ryszard.laskowski@uj.edu.p [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Kooijman, Sebastiaan A.L.M., E-mail: bas@bio.vu.n [Vrije Universiteit of Amsterdam, Dept of Theoretical Biology, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)

    2010-01-15

    We exposed flour beetles (Tribolium castaneum) to a mixture of four poly aromatic hydrocarbons (PAHs). The experimental setup was chosen such that the emphasis was on assessing partial effects. We interpreted the effects of the mixture by a process-based model, with a threshold concentration for effects on survival. The behavior of the threshold concentration was one of the key features of this research. We showed that the threshold concentration is shared by toxicants with the same mode of action, which gives a mechanistic explanation for the observation that toxic effects in mixtures may occur in concentration ranges where the individual components do not show effects. Our approach gives reliable predictions of partial effects on survival and allows for a reduction of experimental effort in assessing effects of mixtures, extrapolations to other mixtures, other points in time, or in a wider perspective to other organisms. - We show a mechanistic approach to assess effects of mixtures in low concentrations.

  16. Experimental study on soluble chemical transfer to surface runoff from soil.

    Science.gov (United States)

    Tong, Juxiu; Yang, Jinzhong; Hu, Bill X; Sun, Huaiwei

    2016-10-01

    Prevention of chemical transfer from soil to surface runoff, under condition of irrigation and subsurface drainage, would improve surface water quality. In this paper, a series of laboratory experiments were conducted to assess the effects of various soil and hydraulic factors on chemical transfer from soil to surface runoff. The factors include maximum depth of ponding water on soil surface, initial volumetric water content of soil, depth of soil with low porosity, type or texture of soil and condition of drainage. In the experiments, two soils, sand and loam, mixed with different quantities of soluble KCl were filled in the sandboxes and prepared under different initial saturated conditions. Simulated rainfall induced surface runoff are operated in the soils, and various ponding water depths on soil surface are simulated. Flow rates and KCl concentration of surface runoff are measured during the experiments. The following conclusions are made from the study results: (1) KCl concentration in surface runoff water would decrease with the increase of the maximum depth of ponding water on soil surface; (2) KCl concentration in surface runoff water would increase with the increase of initial volumetric water content in the soil; (3) smaller depth of soil with less porosity or deeper depth of soil with larger porosity leads to less KCl transfer to surface runoff; (4) the soil with finer texture, such as loam, could keep more fertilizer in soil, which will result in more KCl concentration in surface runoff; and (5) good subsurface drainage condition will increase the infiltration and drainage rates during rainfall event and will decrease KCl concentration in surface runoff. Therefore, it is necessary to reuse drained fertile water effectively during rainfall, without polluting groundwater. These study results should be considered in agriculture management to reduce soluble chemical transfer from soil to surface runoff for reducing non-point sources pollution.

  17. Development of test stand for experimental investigation of chemical and physical phenomena in Liquid Rocket Engine

    OpenAIRE

    Emerson Andrade Santos; Wilton Fernandes Alves; André Neves Almeida Prado; Cristiane Aparecida Martins

    2011-01-01

    Abstract The main objective of this work was to present the specification of an experimental firing test stand for liquid rocket engines (LRE) and develop a program for control and acquisition of data. It provides conditions to test rocket engines with thrust from 50 to 100 kgf. A methodology for laboratory work implementation using information technology, which will allow the automatic and remote functioning of the test stand, permits users to input the necessary data to conduct tests safely...

  18. Enthalpy-Entropy Compensation Effect in Chemical Kinetics and Experimental Errors: A Numerical Simulation Approach.

    Science.gov (United States)

    Perez-Benito, Joaquin F; Mulero-Raichs, Mar

    2016-10-06

    Many kinetic studies concerning homologous reaction series report the existence of an activation enthalpy-entropy linear correlation (compensation plot), its slope being the temperature at which all the members of the series have the same rate constant (isokinetic temperature). Unfortunately, it has been demonstrated by statistical methods that the experimental errors associated with the activation enthalpy and entropy are mutually interdependent. Therefore, the possibility that some of those correlations might be caused by accidental errors has been explored by numerical simulations. As a result of this study, a computer program has been developed to evaluate the probability that experimental errors might lead to a linear compensation plot parting from an initial randomly scattered set of activation parameters (p-test). Application of this program to kinetic data for 100 homologous reaction series extracted from bibliographic sources has allowed concluding that most of the reported compensation plots can hardly be explained by the accumulation of experimental errors, thus requiring the existence of a previously existing, physically meaningful correlation.

  19. Renormalization of loop functions for all loops

    International Nuclear Information System (INIS)

    Brandt, R.A.; Neri, F.; Sato, M.

    1981-01-01

    It is shown that the vacuum expectation values W(C 1 ,xxx, C/sub n/) of products of the traces of the path-ordered phase factors P exp[igcontour-integral/sub C/iA/sub μ/(x)dx/sup μ/] are multiplicatively renormalizable in all orders of perturbation theory. Here A/sub μ/(x) are the vector gauge field matrices in the non-Abelian gauge theory with gauge group U(N) or SU(N), and C/sub i/ are loops (closed paths). When the loops are smooth (i.e., differentiable) and simple (i.e., non-self-intersecting), it has been shown that the generally divergent loop functions W become finite functions W when expressed in terms of the renormalized coupling constant and multiplied by the factors e/sup -K/L(C/sub i/), where K is linearly divergent and L(C/sub i/) is the length of C/sub i/. It is proved here that the loop functions remain multiplicatively renormalizable even if the curves have any finite number of cusps (points of nondifferentiability) or cross points (points of self-intersection). If C/sub γ/ is a loop which is smooth and simple except for a single cusp of angle γ, then W/sub R/(C/sub γ/) = Z(γ)W(C/sub γ/) is finite for a suitable renormalization factor Z(γ) which depends on γ but on no other characteristic of C/sub γ/. This statement is made precise by introducing a regularization, or via a loop-integrand subtraction scheme specified by a normalization condition W/sub R/(C-bar/sub γ/) = 1 for an arbitrary but fixed loop C-bar/sub γ/. Next, if C/sub β/ is a loop which is smooth and simple except for a cross point of angles β, then W(C/sub β/) must be renormalized together with the loop functions of associated sets S/sup i//sub β/ = ]C/sup i/ 1 ,xxx, C/sup i//sub p/i] (i = 2,xxx,I) of loops C/sup i//sub q/ which coincide with certain parts of C/sub β/equivalentC 1 1 . Then W/sub R/(S/sup i//sub β/) = Z/sup i/j(β)W(S/sup j//sub β/) is finite for a suitable matrix Z/sup i/j

  20. Mathematical Modeling of Loop Heat Pipes

    Science.gov (United States)

    Kaya, Tarik; Ku, Jentung; Hoang, Triem T.; Cheung, Mark L.

    1998-01-01

    The primary focus of this study is to model steady-state performance of a Loop Heat Pipe (LHP). The mathematical model is based on the steady-state energy balance equations at each component of the LHP. The heat exchange between each LHP component and the surrounding is taken into account. Both convection and radiation environments are modeled. The loop operating temperature is calculated as a function of the applied power at a given loop condition. Experimental validation of the model is attempted by using two different LHP designs. The mathematical model is tested at different sink temperatures and at different elevations of the loop. Tbc comparison of the calculations and experimental results showed very good agreement (within 3%). This method proved to be a useful tool in studying steady-state LHP performance characteristics.

  1. Construction of the blowdown and condensation loop

    Energy Technology Data Exchange (ETDEWEB)

    Park, Choon Kyung; Song, Chul Kyung; Cho, Seok; Chun, S. Y.; Chung, Moon Ki

    1997-12-01

    The blowdown and condensation loop (B and C loop) has been constructed to get experimental data for designing the safety depressurization system (SDS) and steam sparger which are considered to implement in the Korea Next Generation Reactor (KNGR). In this report, system description on the B and C loop is given in detail, which includes the drawings and technical specification of each component, instrumentation and control system, and the operational procedures and the results of the performance testing. (author). 7 refs., 11 tabs., 48 figs.

  2. Towards designing polymers for photovoltaic applications: A DFT and experimental study of polyazomethines with various chemical structures

    Science.gov (United States)

    Wojtkiewicz, Jacek; Iwan, Agnieszka; Pilch, Marek; Boharewicz, Bartosz; Wójcik, Kamil; Tazbir, Igor; Kaminska, Maria

    2017-06-01

    Theoretical studies of polyazomethines (PAZs) with various chemical structures designated for photovoltaic applications are presented. PAZ energy levels and optical properties were calculated within density-functional theory (DFT and TDDFT) framework for 28 oligomers (monomer, dimer and trimer) of PAZs. The correlations between chemical structure of PAZ and location of its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels were examined. It turned out that the presence of triaminophenylene, dimethoxydiphenylene and fluorine group raises the orbital energies. As a consequence, it is a factor which improves the photovoltaic efficiency of solar cell built on the base of the corresponding PAZ and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). On the contrary, quinone, 1,3,5-triazine and perfluorophenylene groups lower orbital energies and have negative influence on the photovoltaic efficiency. Moreover, calculations for methyl, ethyl and butyl analogs of P3HT as well as polythiophenes were performed and compared with the results obtained for PAZs. In addition experimental data are presented, which cover optical, electrochemical and electrical transport properties of the studied PAZs, allowing to determine HOMO and LUMO energies of the polymers and their conductivity. Finally, comparison between calculated and experimental results were made and discussed.

  3. Towards designing polymers for photovoltaic applications: A DFT and experimental study of polyazomethines with various chemical structures.

    Science.gov (United States)

    Wojtkiewicz, Jacek; Iwan, Agnieszka; Pilch, Marek; Boharewicz, Bartosz; Wójcik, Kamil; Tazbir, Igor; Kaminska, Maria

    2017-06-15

    Theoretical studies of polyazomethines (PAZs) with various chemical structures designated for photovoltaic applications are presented. PAZ energy levels and optical properties were calculated within density-functional theory (DFT and TDDFT) framework for 28 oligomers (monomer, dimer and trimer) of PAZs. The correlations between chemical structure of PAZ and location of its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels were examined. It turned out that the presence of triaminophenylene, dimethoxydiphenylene and fluorine group raises the orbital energies. As a consequence, it is a factor which improves the photovoltaic efficiency of solar cell built on the base of the corresponding PAZ and [6,6]-phenyl C 61 butyric acid methyl ester (PCBM). On the contrary, quinone, 1,3,5-triazine and perfluorophenylene groups lower orbital energies and have negative influence on the photovoltaic efficiency. Moreover, calculations for methyl, ethyl and butyl analogs of P3HT as well as polythiophenes were performed and compared with the results obtained for PAZs. In addition experimental data are presented, which cover optical, electrochemical and electrical transport properties of the studied PAZs, allowing to determine HOMO and LUMO energies of the polymers and their conductivity. Finally, comparison between calculated and experimental results were made and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Experimental validation of thermo-chemical algorithm for a simulation of pultrusion processes

    Science.gov (United States)

    Barkanov, E.; Akishin, P.; Miazza, N. L.; Galvez, S.; Pantelelis, N.

    2018-04-01

    To provide better understanding of the pultrusion processes without or with temperature control and to support the pultrusion tooling design, an algorithm based on the mixed time integration scheme and nodal control volumes method has been developed. At present study its experimental validation is carried out by the developed cure sensors measuring the electrical resistivity and temperature on the profile surface. By this verification process the set of initial data used for a simulation of the pultrusion process with rod profile has been successfully corrected and finally defined.

  5. Toxicity evaluation of silver nanoparticles synthesized by chemical and green route in different experimental models.

    Science.gov (United States)

    Vasanth, Shakila Banu; Kurian, Gino A

    2017-12-01

    With the increased exposure of silver nanoparticles (AgNPs) to human beings, the risk and safety should be considered. In this study, nephro-toxicity of AgNPs prepared by chemical and green route (aqueous extract of Desmodium gangeticum root) in rat, proximal epithelial cell lines and renal mitochondria was evaluated. AgNPs (100 mg/kg) were administered orally to the wistar rats. After 15 d, we observed significant changes in the renal architecture of both AgNPs, supported by the urine and blood chemistry data. Further, exposure towards renal epithelial cells and renal mitochondria also confirm the toxic similarities between the AgNPs synthesized from two routes.

  6. Effect of Ash on Oxygen Carriers for the Application of Chemical Looping Combustion to a High Carbon Char; Effet des cendres sur l'activite des porteurs d'oxygene dans la combustion du charbon en boucle chimique

    Energy Technology Data Exchange (ETDEWEB)

    Rubel, A.; Zhang, Y.; Liu, K.; Neathery, J. [University of Kentucky, Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY (United States)

    2011-03-15

    The application of Chemical Looping Combustion (CLC) to solid fuels is being investigated at the University of Kentucky, Center for Applied Energy Research (CAER) with the aim of the development of a Pressurized Chemical Looping Combustion/Gasification (PCLC/G) process for the generation of electricity from coal. One important aspect of the CLC of solid fuel is the understanding of the effect of ash on the reactivity of Oxygen Carriers (OCs). The effect of ash on the redox capabilities of two different iron oxide OCs and on their ability to oxidize coal char was studied. To determine the effect of ash on the reactivity and recycle of the OCs through multiple redox cycles, fly ash from a coal-fired power plant was used. These experiments were performed in a TGMS system using 500 mg of ash/OC mixtures containing different ash concentrations up to 75%. The reducing gas was composed of 10% H{sub 2}, 15% CO, 20% CO{sub 2}, and a balance of Ar and the oxidizing gas was 20% O{sub 2} in Ar. Oxidation/reductions were carried to near completion. The ash was found to contain OC activity related to inherent iron present in the ash confirmed by XRD. This resulted in increased weight gain/loss on oxidation/reduction. The rate of oxidation/reduction increased with ash concentration due to increased porosity of the OC/ash mixture and better access of the reactive gases to the OC target sites. The two OCs were then used to combust a beneficiated coal char in the TGMS with the only oxygen supplied by an iron oxide OC. The starting mixture was 10% char and 90% of one of two OCs studied. The spent material containing reduced OC and ash was re-oxidized and 10% more char was added for a second reduction of the OC and oxidation of the added char. This procedure was repeated for 5 cycles increasing the ash concentrations from 5 to 25% in the char/ash/OC mixture. Carbon removal was 92 to 97.8 and 97.3 to 99.7% for the two different iron oxide OCs tested. Ash was not detrimental to the

  7. Experimental evaporation of hyperacid brines: Effects on chemical composition and chlorine isotope fractionation

    Science.gov (United States)

    Rodríguez, Alejandro; van Bergen, Manfred J.; Eggenkamp, H. G. M.

    2018-02-01

    Hyperacid brines from active volcanic lakes are some of the chemically most complex aqueous solutions on Earth. Their compositions provide valuable insights into processes of elemental transfer from a magma body to the surface and interactions with solid rocks and the atmosphere. This paper describes changes in chemical and δ37Cl signatures observed in a 1750 h isothermal evaporation experiment on hyperacid (pH 0.1) sulphate-chloride brine water from the active lake of Kawah Ijen volcano (Indonesia). Although gypsum was the only evaporite mineral identified in the evolving brine, decreasing Si concentrations may ultimately result in amorphous silica precipitation. Geochemical simulations predict the additional formation of elemental sulphur at lower water activities (aH2O ≤ 0.65) that were not reached in the experiment. Absence of other sulphates and halides despite the high load of dissolved elements (initial TDS ca. 100 g/kg) can be attributed to increased solubility of metals, promoted by extensive formation of complexes between the variety of cations and the major anions (HSO4-, Cl-, F-) present. Chlorine deviations from a conservative behaviour point to losses of gaseous hydrogen chloride (HCl(g)) and consequently an increase in Br/Cl ratios. Chlorine isotope fractionation that accompanied the escape of HCl(g) showed a marked change in sign and magnitude in the course of progressive evaporation of the brine. The calculated factor of fractionation between HCl(g) and dissolved Cl for the initial interval (before 500 h) is positive (1000lnαHCl(g)-Cldiss. = + 1.55 ± 0.49‰to + 3.37 ± 1.11‰), indicating that, at first, the escaping HCl(g) was isotopically heavier than the dissolved Cl remaining in the brine. Conversely, fractionation shifted to the opposite direction in the subsequent interval (1000lnαHCl(g)-Cldiss. = 5.67 ± 0.17‰to - 5.64 ± 0.08‰), in agreement with values reported in literature. It is proposed that Cl isotopic fractionation in

  8. Experimental and quantum chemical studies on poriferasterol - A natural phytosterol isolated from Cassia sophera Linn. (Caesalpiniaceae)

    Science.gov (United States)

    Brahmachari, Goutam; Mondal, Avijit; Nayek, Nayana; Kumar, Abhishek; Srivastava, Ambrish Kumar; Misra, Neeraj

    2017-09-01

    Poriferasterol, a biologically relevant phytosterol, has been isolated and identified first-time from Cassia sophera Linn. (family: Caesalpiniaceae) based on detailed spectral studies. Exhaustive theoretical studies on the molecular structure, vibrational spectra, HOMO, LUMO, MESP surfaces and reactivity descriptor of this plant-derived natural molecule have been performed. The experimentally observed FT-IR spectrum of the title compound has been compared with spectral data obtained by DFT-B3LYP/6-311 + G (d,p) method. The UV-visible spectrum of the title compound has also been recorded and the electronic properties, such as frontier orbitals and band gap energy are measured by TD-DFT approach. The 1H and 13C NMR spectrum has been calculated by using the gauge independent atomic orbital method and compared with the observed data.

  9. Inference of missing data and chemical model parameters using experimental statistics

    Science.gov (United States)

    Casey, Tiernan; Najm, Habib

    2017-11-01

    A method for determining the joint parameter density of Arrhenius rate expressions through the inference of missing experimental data is presented. This approach proposes noisy hypothetical data sets from target experiments and accepts those which agree with the reported statistics, in the form of nominal parameter values and their associated uncertainties. The data exploration procedure is formalized using Bayesian inference, employing maximum entropy and approximate Bayesian computation methods to arrive at a joint density on data and parameters. The method is demonstrated in the context of reactions in the H2-O2 system for predictive modeling of combustion systems of interest. Work supported by the US DOE BES CSGB. Sandia National Labs is a multimission lab managed and operated by Nat. Technology and Eng'g Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell Intl, for the US DOE NCSA under contract DE-NA-0003525.

  10. Thermodynamic properties and equilibrium constant of chemical reaction in nanosystem: An theoretical and experimental study

    International Nuclear Information System (INIS)

    Du, Jianping; Zhao, Ruihua; Xue, Yongqiang

    2012-01-01

    Highlights: ► There is an obvious influence of the size on thermodynamic properties for the reaction referring nano-reactants. ► Gibbs function, enthalpy, entropy and equilibrium constant are dependent on the reactant size. ► There is an approximate linear relation between them. - Abstract: The theoretical relations of thermodynamic properties, the equilibrium constant and reactant size in nanosystem are described. The effects of size on thermodynamic properties and the equilibrium constant were studied using nanosize zinc oxide and sodium bisulfate solution as a reaction system. The experimental results indicated that the molar Gibbs free energy, the molar enthalpy and the molar entropy of the reaction decrease, but the equilibrium constant increases with decreasing reactant size. Linear trends were observed between the reciprocal of size for nano-reactant and thermodynamic variable, which are consistent with the theoretical relations.

  11. Evaluation of the effect of conventionally prepared swarna makshika bhasma on different bio-chemical parameters in experimental animals.

    Science.gov (United States)

    Mohapatra, Sudhaldev; Jha, C B

    2011-10-01

    Swarna makshika (chalcopyrite) bhasma (SMB) has been used for different therapeutic purposes since long in Ayurveda. The present study is conducted to evaluate the effect of conventionally prepared SMB on different bio-chemical parameters in experimental animals, for providing scientific data base for its logical use in clinical practice. The genuine SMB was prepared by following classical techniques of shodhana and marana most commonly used by different Ayurvedic drug manufacturers. Shodhana was done by roasting raw swarna makshika with lemon juice for three days and marana was performed by 11 putas. The experimental animals (rats) were divided into two groups. SMB mixed with diluted honey was administered orally in therapeutic dose to Group SMB and diluted honey only was administered to vehicle control Group, for 30 days. The blood samples were collected twice, after 15 days and after 30 days of drug administration and different biochemical investigations were done. Biochemical parameters were chosen based on references from Ayurvedic classics and contemporary medicine. It was observed that Hb% was found significantly increased and LDL and VLDL were found significantly decreased in Group SMB when compared with vehicle control group. This experimental data will help the clinician for the logical use of SMB in different disease conditions with findings like low Hb% and high LDL, VLDL levels.

  12. Evaluation of the effect of conventionally prepared swarna makshika bhasma on different bio-chemical parameters in experimental animals

    Directory of Open Access Journals (Sweden)

    Sudhaldev Mohapatra

    2011-01-01

    Full Text Available Swarna makshika (chalcopyrite bhasma (SMB has been used for different therapeutic purposes since long in Ayurveda. The present study is conducted to evaluate the effect of conventionally prepared SMB on different bio-chemical parameters in experimental animals, for providing scientific data base for its logical use in clinical practice. The genuine SMB was prepared by following classical techniques of shodhana and marana most commonly used by different Ayurvedic drug manufacturers. Shodhana was done by roasting raw swarna makshika with lemon juice for three days and marana was performed by 11 putas . The experimental animals (rats were divided into two groups. SMB mixed with diluted honey was administered orally in therapeutic dose to Group SMB and diluted honey only was administered to vehicle control Group, for 30 days. The blood samples were collected twice, after 15 days and after 30 days of drug administration and different biochemical investigations were done. Biochemical parameters were chosen based on references from Ayurvedic classics and contemporary medicine. It was observed that Hb% was found significantly increased and LDL and VLDL were found significantly decreased in Group SMB when compared with vehicle control group. This experimental data will help the clinician for the logical use of SMB in different disease conditions with findings like low Hb% and high LDL, VLDL levels.

  13. Experimental determination of the bulk temperature values in a nonisothermal flow of the chemically reacting nitrogen tetroxide

    International Nuclear Information System (INIS)

    Devojno, A.N.; Kolykhan, L.I.; Stepanenko, V.N.; Tverkovkin, B.E.; Uyutov, G.I.

    1975-01-01

    The technique and results of an experimental determination of mean mass temperatures of a cooled chemically active nitrogen tetroxide flowing in a circular tube under turbulent flow conditions are considered. The parameters range as follows: pressure-from 8.10 5 to 16.10 5 H/m 2 , flow temperature-from 140 deg to 550 deg C, Reynolds number-from 3,1.1g 5 , flow velocity-from 3.5 to 45 m/s. The gas temperature along the length of the test tube is measured with movable probe with a mixer and thermocouple in a stainless steel capillary 2mm in dia and the wall 0,2 mm thick. The mean-square deviations of measured temperature values from the predicted ones are about -0.9 and +1.8%. The obtained data show the predicted temperature values to be somewhat lower than the measured ones, the difference increasing with the distance to the test tube outlet. It may be explained by both unaccounted systematic experimental errors and errors in calculating the mean mass flow temperatures. The investigation described confirms the possibility of an experimental determination of the mean gas temperature along the cooled channel length by mean mass of a movable mixer with a single thermocouple

  14. Chemical activation of molecules by metals: Experimental studies of electron distributions and bonding

    International Nuclear Information System (INIS)

    Lichtenberger, D.L.

    1991-10-01

    The formal relationship between measured molecular ionization energies and thermodynamic bond dissociation energies has been developed into a single equation which unifies the treatment of covalent bonds, ionic bonds, and partially ionic bonds. This relationship has been used to clarify the fundamental thermodynamic information relating to metal-hydrogen, metal-alkyl, and metal-metal bond energies. We have been able to obtain a direct observation and measurement of the stabilization energy provided by the agostic interaction of the C-H bond with the metal. The ionization energies have also been used to correlate the rates of carbonyl substitution reactions of (η 5 -C 5 H 4 X)Rh(CO) 2 complexes, and to reveal the electronic factors that control the stability of the transition state. The extent that the electronic features of these bonding interactions transfer to other chemical systems is being investigated in terms of the principle of additivity of ligand electronic effects. Specific examples under study include metal- phosphines, metal-halides, and metallocenes. Especially interesting has been the recent application of these techniques to the characterization of the soccer-ball shaped C 60 molecule, buckminsterfullerene, and its interaction with a metal surface. The high-resolution valence ionizations in the gas phase reveal the high symmetry of the molecule, and studies of thin films of C 60 reveal weak intermolecular interactions. Scanning tunneling and atomic force microscopy reveal the arrangement of spherical molecules on gold substrates, with significant delocalization of charge from the metal surface. 21 refs

  15. Synthesis and Self-Assembly of Gold Nanoparticles by Chemically Modified Polyol Methods under Experimental Control

    Directory of Open Access Journals (Sweden)

    Nguyen Viet Long

    2013-01-01

    Full Text Available In our present research, bottom-up self-assembly of gold (Au nanoparticles on a flat copper (Cu substrate is performed by a facile method. The very interesting evidence of self-assembly of Au nanoparticles on the top of the thin assembled layer was observed by scanning electron microscopy (SEM. We had discovered one of the most general and simple methods for the self-assembly of metal nanoparticles. The general physical and chemical mechanisms of the evaporation process of the solvents can be used for self-assembly of the as-prepared nanoparticles. The important roles of molecules of the used solvents are very critical to self-assembly of the as-prepared Au nanoparticles in the case without using any polymers for those processes. It is clear that self-assembly of such one nanosystem of the uniform Au nanoparticles is fully examined. Finally, an exciting surface plasmon resonance (SPR phenomenon of the pure Au nanoparticles in the solvent was fully discovered in their exciting changes of the narrow and large SPR bands according to synthesis time. The SPR was considered as the collective oscillation of valence electrons of the surfaces of the pure Au nanoparticles in the solvent by incident ultraviolet-visible light. Then, the frequency of light photons matches the frequency of the oscillation of surface electrons of the Au nanoparticles that are excited.

  16. Experimental and theoretical studies on physico-chemical parameters affecting the solubility of phosphogypsum

    Energy Technology Data Exchange (ETDEWEB)

    Papanicolaou, Fanos; Antoniou, Stella [Chemistry Department, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Pashalidis, Ioannis [Chemistry Department, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus)], E-mail: pspasch@ucy.ac.cy

    2009-10-15

    Phosphogypsum is a waste by-product of the phosphate fertilizer industry, which is usually disposed in the environment because of its restricted use in industrial applications. Physico-chemical conditions existing in stack fluids and leachates are of major importance and determine solubility and redox stability of phosphogypsum, as well as radionuclide release from stacks to terrestrial environments. The aim of this study is to assess the effect of key parameters (e.g. ionic strength, temperature, pH) on the solubility of phosphogypsum. Phosphogypsum sampling and in-situ measurements were carried out at a coastal stack in Cyprus, solubility experiments were performed in simulated laboratory systems and thermodynamic calculations by means of MINTEQA2, an equilibrium speciation model. Generally, increasing ionic strength and temperature leads to increased phosphogypsum solubility, with the former being much more effective. The increased solubility of phosphogypsum in saline solutions is attributed solely to ionic strength effects on the activity of ionic species in solution and no solid phase transformations could be observed. The effect of pH on phosphogypsum solubility seems to be insignificant at least in a pH range between 4 and 8. Regarding uranium levels, there is a strong correlation between salinity and uranium concentration and linear correlation between phosphogypsum solubility and uranium levels in stack solutions, indicating the incorporation of uranium into the gypsum lattice and the formation of a solid solution.

  17. Experimental and theoretical studies on physico-chemical parameters affecting the solubility of phosphogypsum.

    Science.gov (United States)

    Papanicolaou, Fanos; Antoniou, Stella; Pashalidis, Ioannis

    2009-10-01

    Phosphogypsum is a waste by-product of the phosphate fertilizer industry, which is usually disposed in the environment because of its restricted use in industrial applications. Physico-chemical conditions existing in stack fluids and leachates are of major importance and determine solubility and redox stability of phosphogypsum, as well as radionuclide release from stacks to terrestrial environments. The aim of this study is to assess the effect of key parameters (e.g. ionic strength, temperature, pH) on the solubility of phosphogypsum. Phosphogypsum sampling and in-situ measurements were carried out at a coastal stack in Cyprus, solubility experiments were performed in simulated laboratory systems and thermodynamic calculations by means of MINTEQA2, an equilibrium speciation model. Generally, increasing ionic strength and temperature leads to increased phosphogypsum solubility, with the former being much more effective. The increased solubility of phosphogypsum in saline solutions is attributed solely to ionic strength effects on the activity of ionic species in solution and no solid phase transformations could be observed. The effect of pH on phosphogypsum solubility seems to be insignificant at least in a pH range between 4 and 8. Regarding uranium levels, there is a strong correlation between salinity and uranium concentration and linear correlation between phosphogypsum solubility and uranium levels in stack solutions, indicating the incorporation of uranium into the gypsum lattice and the formation of a solid solution.

  18. Prediction of Physico-chemical Properties of Bacteriostatic N1-Substituted Sulfonamides: Theoretical and Experimental Studies.

    Science.gov (United States)

    Nikoofard, Hossein; Sargolzaei, Mohsen; Faridbod, Farnosh

    2017-12-01

    A computational study at the density functional theory (DFT) as well as electrochemical methods, was carried out on the structural and physico-chemical properties of a series of sulfonamide derivatives (SAs) as WHO essential medications in the treatment of basic health system. The B3LYP/6-311++G(d,p) level of theory carried out on sulfadiazine (SDZ), sulfathiazole (STZ), sulfaquinoxaline (SQX), sulfacetamide (SAA), and the reference unsubstituted sulfonamide (SA) was discussed and rationalized in term of the N1-sulfonamide substituent. The geometric structures and the electronic properties related to the bacteriostatic reactivity were revealed to be affected by the steric and "push-pull" characteristics of the substituents. Electrochemical experiments on oxidation of SAs, using cyclic voltammetry are presented. The results obtained showed that the calculated ionization potentials (IPs) could be correlated linearly with the electro-oxidation potentials. From the molecules studied it is evident that SDZ act as the most electro-active agent, possessing the highest biological activity. DFT computations carried out using the standard molar enthalpies of formation in the gas phase predicted improvements in the thermodynamic stabilization of the SDZ, SQX, and SAA molecules and an unstabilization of STZ with respect to the parent molecule SA.

  19. On loop extensions and cohomology of loops

    OpenAIRE

    Benítez, Rolando Jiménez; Meléndez, Quitzeh Morales

    2015-01-01

    In this paper are defined cohomology-like groups that classify loop extensions satisfying a given identity in three variables for association identities, and in two variables for the case of commutativity. It is considered a large amount of identities. This groups generalize those defined in works of Nishigori [2] and of Jhonson and Leedham-Green [4]. It is computed the number of metacyclic extensions for trivial action of the quotient on the kernel in one particular case for left Bol loops a...

  20. Neutron transport in irradiation loops (IRENE loop)

    International Nuclear Information System (INIS)

    Sarsam, Maher.

    1980-09-01

    This thesis is composed of two parts with different aspects. Part one is a technical description of the loop and its main ancillary facilities as well as of the safety and operational regulations. The measurement methods on the model of the ISIS reactor and on the loop in the OSIRIS reactor are described. Part two deals with the possibility of calculating the powers dissipated by each rod of the fuel cluster, using appropriate computer codes, not only in the reflector but also in the core and to suggest a method of calculation [fr

  1. Hydrogen production with CO 2 capture by coupling steam reforming of methane and chemical-looping combustion: Use of an iron-based waste product as oxygen carrier burning a PSA tail gas

    Science.gov (United States)

    Ortiz, María; Gayán, Pilar; de Diego, Luis F.; García-Labiano, Francisco; Abad, Alberto; Pans, Miguel A.; Adánez, Juan

    In this work it is analyzed the performance of an iron waste material as oxygen carrier for a chemical-looping combustion (CLC) system. CLC is a novel combustion technology with the benefit of inherent CO 2 separation that can be used as a source of energy for the methane steam reforming process (SR). The tail gas from the PSA unit is used as fuel in the CLC system. The oxygen carrier behaviour with respect to gas combustion was evaluated in a continuous 500 W th CLC prototype using a simulated PSA off-gas stream as fuel. Methane or syngas as fuel were also studied for comparison purposes. The oxygen carrier showed enough high oxygen transport capacity and reactivity to fully convert syngas at 880 °C. However, lower conversion of the fuel was observed with methane containing fuels. An estimated solids inventory of 1600 kg MW th -1 would be necessary to fully convert the PSA off-gas to CO 2 and H 2O. An important positive effect of the oxygen carrier-to-fuel ratio up to 1.5 and the reactor temperature on the combustion efficiency was found. A characterization of the calcined and after-used particles was carried out showing that this iron-based material can be used as oxygen carrier in a CLC plant since particles maintain their properties (reactivity, no agglomeration, high durability, etc.) after more than 111 h of continuous operation.

  2. Chemical Looping Combustion of Solid Fuels in a Laboratory Fluidized-bed Reactor Combustion de charges solides avec la boucle chimique dans un lit fluidisé de laboratoire

    Directory of Open Access Journals (Sweden)

    Leion H.

    2011-02-01

    Full Text Available When using solid fuel in a chemical looping system, the char fraction of the fuel needs to be gasified before syngas react with the oxygen carrier. This can be done inside the fuel reactor with fuel and oxygen carriers well mixed, and, since this gasification is comparably slow, this will be the time limiting step of such a system. An option is to use an oxygen carrier that is able to release gas-phase oxygen which can react with the fuel by normal combustion giving a significantly faster overall fuel conversion. This last option is generally referred to as Chemical Looping combustion with Oxygen Un-coupling (CLOU. In this work, an overview is given of parameters that affect the fuel conversion in laboratory CLC and CLOU experiments. The main factor determining the fuel conversion, in both CLC and CLOU, is the fuel itself. High-volatile fuels are generally more rapidly converted than low volatile fuels. This difference in fuel conversion rate is more pronounced in CLC than in CLOU. However, the fuel conversion is also, both for CLC and CLOU, increased by increasing temperature. Increased steam and SO2 fraction in the surrounding gas will also enhance the fuel conversion in CLC. CO2 gasification in CLC appears to be very slow in comparison to steam gasification. H2 can inhibit fuel gasification in CLC whereas CO did not seem to have any effect. Possible deactivation of oxygen carriers due to SO2 or ash also has to be considered. Lorsque l’on utilise des combustibles solides dans la boucle chimique (CLC pour Chemical Looping Combustion, il est nécessaire de gazéifier le char avant de faire la combustion du gaz de synthèse au contact du transporteur d’oxygène. Ces réactions peuvent s’effectuer dans le réacteur fuel, dans lequel le combustible et le transporteur d’oxygène sont bien mélangés. Cependant, la gazéification du charbon est lente et reste l’étape limitante du processus de combustion dans ces conditions. Une alternative

  3. Oxygen termination of homoepitaxial diamond surface by ozone and chemical methods: An experimental and theoretical perspective

    Science.gov (United States)

    Navas, Javier; Araujo, Daniel; Piñero, José Carlos; Sánchez-Coronilla, Antonio; Blanco, Eduardo; Villar, Pilar; Alcántara, Rodrigo; Montserrat, Josep; Florentin, Matthieu; Eon, David; Pernot, Julien

    2018-03-01

    Phenomena related with the diamond surface of both power electronic and biosensor devices govern their global behaviour. In particular H- or O-terminations lead to wide variations in their characteristics. To study the origins of such aspects in greater depth, different methods to achieve oxygen terminated diamond were investigated following a multi-technique approach. DFT calculations were then performed to understand the different configurations between the C and O atoms. Three methods for O-terminating the diamond surface were performed: two physical methods with ozone at different pressures, and an acid chemical treatment. X-ray photoelectron spectroscopy, spectroscopic ellipsometry, HRTEM, and EELS were used to characterize the oxygenated surface. Periodic-DFT calculations were undertaken to understand the effect of the different ways in which the oxygen atoms are bonded to carbon atoms on the diamond surface. XPS results showed the presence of hydroxyl or ether groups, composed of simple Csbnd O bonds, and the acid treatment resulted in the highest amount of O on the diamond surface. In turn, ellipsometry showed that the different treatments led to the surface having different optical properties, such as a greater refraction index and extinction coefficient in the case of the sample subjected to acid treatment. TEM analysis showed that applying temperature treatment improved the distribution of the oxygen atoms at the interface and that this generates a thinner amount of oxygen at each position and higher interfacial coverage. Finally, DFT calculations showed both an increase in the number of preferential electron transport pathways when π bonds and ether groups appear in the system, and also the presence of states in the middle of the band gap when there are π bonds, Cdbnd C or Cdbnd O.

  4. A combined experimental (IR, Raman and UV-Vis) and quantum chemical study of canadine

    Science.gov (United States)

    Joshi, Bhawani Datt; Srivastava, Anubha; Tandon, Poonam; Jain, Sudha; Ayala, A. P.

    2018-02-01

    Plant based natural products cover a major sector of the medicinal field, as such focus on plant research has been increased all over the world. As an attempt to aid that research, we have performed structural and spectroscopic analysis of a natural product, an alkaloid: canadine. Both ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP using 6-311 ++G(d,p) basis set were used for the calculations. The calculated vibrational frequencies were scaled and compared with the experimental infrared and Raman spectra. The complete vibrational assignments were made using potential energy distribution. The structure-activity relation has also been interpreted by mapping electrostatic potential surface and evaluating the reactivity descriptors, which are valuable information for quality control of medicines and drug-receptor interactions. Natural bond orbital analysis has also been performed to understand the stability and hyperconjugative interactions of the molecule. Furthermore, UV-Vis spectra have been recorded in an ethanol solvent (EtOH) and the electronic property has been analyzed employing TD-DFT for both gaseous and solvent phase. The HOMO and LUMO calculation with their energy gap show that charge transfer occurs within the molecule. Additionally, the nonlinear optical properties of the title compound have been interpreted that predicts it's the best candidate for the NLO materials.

  5. Hematological, antioxidant and protective performance of Usnea longissima on chemical induced hepatotoxicity in experimental animals

    Directory of Open Access Journals (Sweden)

    Pritt Verma

    2017-05-01

    Full Text Available Objective: To investigated the hematological, antioxidant and protective performance of Usnea longissima (U. longissima on CCl4 induced hepatotoxicity in experimental animals. Methods: Hepatotoxicity was induced by CCl4 (1 mL/kg body weigt 1:1 CCl4 i.p., ethanolic U. longissima extracts at a doses (200 and 400 mg/kg body weigt were administered to and compared with Silymarin (25 mg/kg body weigt and hematological, antioxidant and enzymatic, non-enzymatic parameters were assessed through the liver functions test. All the observation was also supplemented with histopathological examination of liver sections. Results: Phytochemical investigation showed that ethanolic extract contains poly phenolic compounds tannins, flavonoids, alkaloids and saponins and acute toxicity study shows that ethanolic extract was safe up to 2 000 mg/kg body weight. The toxicant induced a rise in the plasma enzyme levels of ALT, AST, ALP and total bilirubin level. This increased level was significantly decreased by the extract at 400 mg/kg body weight than 200 mg/kg body weight. The animals were prevented (partly or fully which was showed in the histopathological changes using ethonolic U. longissima extract. Conclusions: The outcome of this study reveals that, there is a powerful antioxidant and hepatoprotective activity of U. longissima. It is believed that the present constituents are responsible for courting the hepatic disease and alternative components have the power to act as free radical scavenging properties.

  6. Effect of therapeutic chemical agents in vitro and on experimental meningoencephalitis due to Naegleria fowleri.

    Science.gov (United States)

    Kim, Jong-Hyun; Jung, Suk-Yul; Lee, Yang-Jin; Song, Kyoung-Ju; Kwon, Daeho; Kim, Kyongmin; Park, Sun; Im, Kyung-Il; Shin, Ho-Joon

    2008-11-01

    Naegleria fowleri is a ubiquitous, pathogenic free-living amoeba; it is the most virulent Naegleria species and causes primary amoebic meningoencephalitis (PAME) in laboratory animals and humans. Although amphotericin B is currently the only agent available for the treatment of PAME, it is a very toxic antibiotic and may cause many adverse effects on other organs. In order to find other potentially therapeutic agents for N. fowleri infection, the present study was undertaken to evaluate the in vitro and in vivo efficacies of miltefosine and chlorpromazine against pathogenic N. fowleri. The result showed that the growth of the amoeba was effectively inhibited by treatment with amphotericin B, miltefosine, and chlorpromazine. When N. fowleri trophozoites were treated with amphotericin B, miltefosine, and chlorpromazine, the MICs of the drug were 0.78, 25, and 12.5 microg/ml, respectively, on day 2. In experimental meningoencephalitis of mice that is caused by N. fowleri, the survival rates of mice treated with amphotericin B, miltefosine, and chlorpromazine were 40, 55, and 75%, respectively, during 1 month. The average mean time to death for the amphotericin B, miltefosine, and chlorpromazine treatments was 17.9 days. In this study, the effect of drugs was found to be optimal when 20 mg/kg was administered three times on days 3, 7, and 11. Finally, chlorpromazine had the best therapeutic activity against N. fowleri in vitro and in vivo. Therefore, it may be a more useful therapeutic agent for the treatment of PAME than amphotericin B.

  7. Influence of polymeric matrix on the physical and chemical properties of experimental composites

    Directory of Open Access Journals (Sweden)

    Flávia GONÇALVES

    2015-01-01

    Full Text Available Nowadays, the main reasons for replacement of resin-based composite restorations are fracture or problems with the integrity of their interface, such as marginal staining, microleakage, or secondary caries. The aim of the present study was to evaluate the influence of the organic matrix on polymerization stress (PS, degree of conversion (DC, elastic modulus (E, flexural strength (FS, Knoop hardness (KHN, sorption (SP, and solubility (SL. In order to obtain a material which combines better mechanical properties with lower PS, seven experimental composites were prepared using BisGMA to TEGDMA molar ratios of 2:8, 3:7, 4:6, 5:5, 6:4, 7:3 and 8:2 and 40% of silica. PS was obtained in a universal testing machine, using acrylic as bonding substrate. DC was determined using Fourier Transform Raman spectroscopy. E and FS were obtained by the three-point bending test. KHN was measured by a microindentation test using a load of 25 g for 30 s. SP and SL were assessed according to ISO 4049. The data were submitted to one-way ANOVA. The increase in BisGMA concentration resulted in the decrease of PS, DC, E, FS and KHN. However, it did not change the SP and SL values. FS, E and KHN showed a strong and direct relationship with the DC of the materials. The composite material with a BisGMA to TEGDMA molar ratio of 1:1 was the one with better mechanical properties and lower PS.

  8. Interaction of anthraquinone anti-cancer drugs with DNA:Experimental and computational quantum chemical study

    Science.gov (United States)

    Al-Otaibi, Jamelah S.; Teesdale Spittle, Paul; El Gogary, Tarek M.

    2017-01-01

    Anthraquinones form the basis of several anticancer drugs. Anthraquinones anticancer drugs carry out their cytotoxic activities through their interaction with DNA, and inhibition of topoisomerase II activity. Anthraquinones (AQ4 and AQ4H) were synthesized and studied along with 1,4-DAAQ by computational and experimental tools. The purpose of this study is to shade more light on mechanism of interaction between anthraquinone DNA affinic agents and different types of DNA. This study will lead to gain of information useful for drug design and development. Molecular structures were optimized using DFT B3LYP/6-31 + G(d). Depending on intramolecular hydrogen bonding interactions two conformers of AQ4 were detected and computed as 25.667 kcal/mol apart. Molecular reactivity of the anthraquinone compounds was explored using global and condensed descriptors (electrophilicity and Fukui functions). Molecular docking studies for the inhibition of CDK2 and DNA binding were carried out to explore the anti cancer potency of these drugs. NMR and UV-VIS electronic absorption spectra of anthraquinones/DNA were investigated at the physiological pH. The interaction of the three anthraquinones (AQ4, AQ4H and 1,4-DAAQ) were studied with three DNA (calf thymus DNA, (Poly[dA].Poly[dT]) and (Poly[dG].Poly[dC]). NMR study shows a qualitative pattern of drug/DNA interaction in terms of band shift and broadening. UV-VIS electronic absorption spectra were employed to measure the affinity constants of drug/DNA binding using Scatchard analysis.

  9. Decoding the Mobility and Time Scales of Protein Loops.

    Science.gov (United States)

    Gu, Yina; Li, Da-Wei; Brüschweiler, Rafael

    2015-03-10

    The flexible nature of protein loops and the time scales of their dynamics are critical for many biologically important events at the molecular level, such as protein interaction and recognition processes. In order to obtain a predictive understanding of the dynamic properties of loops, 500 ns molecular dynamics (MD) computer simulations of 38 different proteins were performed and validated using NMR chemical shifts. A total of 169 loops were analyzed and classified into three types, namely fast loops with correlation times Web server (http://spin.ccic.ohio-state.edu/index.php/loop). The results demonstrate that loop dynamics with their time scales can be predicted rapidly with reasonable accuracy, which will allow the screening of average protein structures to help better understand the various roles loops can play in the context of protein-protein interactions and binding.

  10. MATLAB: For While Loops

    OpenAIRE

    2005-01-01

    sim tut Simulation Tutorial Interactive Media Element This interactive tutorial on MATLAB covers the For Loop and the While Loop functions. Examples are provided with step-by-step animated explanations. The interactions involve entering MATLAB instructions and observing the outcomes. Self-check questions are provided to help learners determine their level of understanding of the content presented. EC1010 Introduction to MATLAB

  11. Water loop for training

    International Nuclear Information System (INIS)

    Moeller, S.V.

    1983-02-01

    The procedures used to operate the water loop of the Institute of Nuclear Enginering (IEN) in Brazil are presented. The aim is to help future operators of the training water loop in the operation technique and in a better comprehension of the phenomena occured during the execution of an experience. (E.G.) [pt

  12. Experimental Demonstration Center at Mining Chemical Combine as a prototype of Third Generation Plant for Thermal Reactor SNF Reprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Kudryavtsev, E.G.; Haperskaya, A.V. [GC Rosatom (Russian Federation); Gavrilov, P.M.; Revenko, Yu.A.; Bondin, V.V. [MCC, Zeleznogorsk (Russian Federation); Fedorov, Yu.S.; Shadrin, A.Yu. [Khlopin Radium Institute, 2nd Murinsky Ave., 28, Saint Petersburg, 194021 (Russian Federation); Shafrova, N.P.; Smirnov, Yu.V. [GI VNIPIET, St. Petersburg (Russian Federation)

    2009-06-15

    Development of reprocessing and balanced use of the products of the spent nuclear fuel (SNF) regeneration in the nuclear fuel cycle is a primary trend of the SNF management in Russia. In future, the program of extensive building of the nuclear power plants (NPP), presented in the General Scheme of arrangement of the power industry objects up to 2020 and approved by the Government of the Russian Federation, will lead to the additional accumulation of significant volumes of SNF. The problem of SNF accumulated both from previous activity and at operation of new NPP blocks can be solved by building of the large-scale reprocessing plant RT-2 based on perspective efficient processes of SNF reprocessing and radioactive waste management, which would provide the best economical and ecological characteristics as compared to the modern radiochemical plants. The Experimental Demonstration Center is now designed to check the key points of the perspective technologies and to obtain practical experience on operation to reduce the volumes of the technological and non-technological liquid radioactive wastes (LRW). Few technological flowsheet, including Simplified PUREX-process as a basic one, are being developed within the program 'Development of the Experimental Demonstration Center for SNF reprocessing based on innovation technologies'. Development of new flowsheet will allow to decrease the LRW volume and to reduce the cost of SNF reprocessing. Sharp reduce in the volume of technological LRW is due to tritium release from SNF in the head of the process, would provide development of the closed water cycle. Improvement of the economical characteristics is related with innovation procedures of the SNF decladding, dissolution, processing and LWR management, which would intensify and improve key processes and, thus, reduce the number of technological operations. For this purpose a series of novel and unique equipment (such as a unit for thermo-chemical destruction of the

  13. Experimental and theoretical study on chemical reactions and species diffusion by a nano-pulse discharged bubble for water treatment

    Science.gov (United States)

    He, Yuchen; Uehara, Satoshi; Takana, Hidemasa; Nishiyama, Hideya

    2018-01-01

    Advanced oxidation processes using hydroxyl radicals (ṡOH) generated inside bubbles in water has drawn widely interest for the high oxidation potential of OH radical to decompose persistent organic pollutants such as dioxins and humic acid for water purification. In this study, a two-dimensional diffusion model for a nano-pulse discharged bubble in water is established. Based on the experimental results of streamer propagation inside a bubble, the diffusion processes around the bubble interface and reactions of chemical species in liquids are simulated. The simulation results show that OH radicals can diffuse only several micrometers away from the bubble interface in water. Furthermore, the optimal operating voltage and frequency conditions for OH generation is obtained by comparing the OH concentration in water obtained from numerical simulation with that measured by spectroscopy in experiment.

  14. Migration and chemical extractability of 137Cs and 90Sr in Swedish long-term experimental pastures

    International Nuclear Information System (INIS)

    Forsberg, S.; Strandmark, M.

    1999-01-01

    Vertical migration and chemical extractability were studied on two experimental pastures, a sandy soil and a clay soil, contaminated with 137 Cs and 90 Sr in 1961. Migration was studied by measuring the total nuclide content in soil samples to 55 cm depth, chemical extractability by sequential extraction. Both 137 Cs and 90 Sr were found at all depths in both soils, and 90 Sr had moved deeper than 137 Cs. 137 Cs was mainly found in the upper 10 cm, and no difference was seen between clay and sandy soil, due to retention in the root mat of the sandy soil. 90 Sr had moved deeper in sandy than in clay soil, the reason being the higher exchange capacity of the clay soil. Sequential extractions showed that 90 Sr was much more extractable than 137 Cs. 96-98% of 137 Cs was found in the HNO 3 and residual fractions. 137 Cs was more extractable in the sandy soil than in clay, and in the sandy soil the extractability of 137 Cs increased slightly with depth. Regarding 90 Sr, 63-75% was found in the easily exchangeable fractions, the higher figure was in clay soil. A large proportion, 18-30%, was extracted in the reducible fraction, showing that availability of 90 Sr might increase under reducing conditions. (au)

  15. Characterization and chemical activity of Portland cement and two experimental cements with potential for use in dentistry.

    Science.gov (United States)

    Camilleri, J

    2008-09-01

    To evaluate the chemical activity of Portland cement and two other cement types with similar chemical composition to mineral trioxide aggregate with the aim of developing these cements for further applications in dentistry. The chemical composition of the three cement types namely Portland cement, calcium sulpho-aluminate cement and calcium fluoro-aluminate cement was evaluated by elemental analysis using energy dispersive analysis with X-ray under the scanning electron microscope and by X-ray diffraction analysis (XRD) to determine the phases. The constituents of the hydration reaction by-products were evaluated by XRD analysis of the set cements at 1, 7, 28 and 56 days and by analysis of the leachate by ion chromatography. The pH of both cements and leachate was determined at different time intervals. Cements admixed with micro-silica were also tested to determine the effect of micro-silica on the reaction by-products. All three cement types were composed of tricalcium silicate as the main constituent phase. The hydration reaction of Portland cement produced calcium hydroxide. However, this was not present in the other cements tested at all ages. Admixed micro-silica had little or no effect on the cements with regard to reaction by-products. The pH of all cements tested was alkaline. Both the experimental calcium sulpho-aluminate cement and calcium fluoro-aluminate cement had different hydration reactions to that of Portland cement even though calcium silicate was the major constituent element of both cement types. No calcium hydroxide was produced as a by-product to cement hydration. Micro-silica addition to the cement had no effect on the hydration reaction.

  16. Chemical bond in borides. Theoretical and experimental analysis; Chemische Bindung in Boriden. Theoretische und experimentelle Untersuchung

    Energy Technology Data Exchange (ETDEWEB)

    Sagawe, Vanessa

    2013-04-18

    The aim of this work was the analysis of the bonding situation in different borides by examining the electron density in these structures. The main focus of the analysis was on the QTAIM analysis and the evaluation of the Electron Localizability Indicator (ELI-D). For the calculation of the electron density different methods (extended Hueckel, LMTO, (L)APW) were used to prove which method leads to most precise results. The (L)APW-method was found to be the most exact one and the one with the longest computational times. The examined compounds were boron-rich Borides containing icosahedra, Transition Metal Borides and Na{sub 3}B{sub 20}. Most of the structures of the examined boron-rich Borides can be derived directly from the MgB{sub 7} structure type (MgB{sub 7}, MgB{sub 12}C{sub 2}, LiB{sub 13}C{sub 2}, Li{sub 2}B{sub 12}C{sub 2}, LiB{sub 12}PC). The influence of the different cations as well as the interstitial atoms could be analyzed by comparing these compounds. Structures which can be derived from the alpha-rhombohedral Boron were also analyzed (B{sub 12}O{sub 2}, B{sub 12}P{sub 2}, B{sub 12}As{sub 2}). Assuming Bader-Charges the icosahedron is always positively charged if the electronegativity of the interstitial atoms is higher than the electronegativity of the Boron atoms. If their electronegativitiy is lower, the icosahedra are negatively charged. From the ELI-D-basins the bonding situation can be analyzed according to Wade by bisecting the basins of the exohedral bonds. The icosahedra are always negatively charged. However, Wade's rule is never exactly fulfilled as the charge is never exactly -2. To verify the results from theoretical calculations and vice versa, experimental electron density analyses of MgB{sub 7} and Li{sub 2}B{sub 12}C{sub 2} were performed. However, only the examination of MgB{sub 7} gave reliable results. They promoted the results by the calculations and underlined the correctness of the used methods. Results received by single

  17. Chemical-physical properties of experimental root canal sealers based on butyl ethylene glycol disalicylate and MTA.

    Science.gov (United States)

    Vitti, Rafael P; Prati, Carlo; Sinhoreti, Mário Alexandre C; Zanchi, Cesar H; Souza E Silva, Manuela G; Ogliari, Fabrício A; Piva, Evandro; Gandolfi, Maria G

    2013-12-01

    The aim of this study was to evaluate the calcium release, pH, flow, solubility, water absorption, setting and working time of three experimental root canal sealers based on mineral trioxide aggregate (MTA) and two forms of calcium phosphates (CaP). The materials were composed of a base and a catalyst pastes mixed in a 1:1. The base paste was made by 60% bismuth oxide and 40% butyl ethylene glycol disalicylate. Three different catalyst pastes were formulated containing 60% MTA or 40% MTA+20% CaP (hydroxyapatite HA or dibasic calcium phosphate dehydrate DCPD), 39% Resimpol 8% and 1% titanium dioxide. MTA Fillapex was used as control. The release of calcium and hydroxyl ions, solubility and water absorption were measured on regular intervals for 28 days. The working time and flow were tested according to ISO 6876:2001 and the setting time according to ASTM C266. The data were analyzed using 1-way ANOVA with Tukey's test (p<.01). All the cements showed basifying activity and released calcium ions. MTA Fillapex showed the highest values of flow (p<.01) and working/setting times (p<.01) and the smallest values of solubility (p<.01) and water absorption (p<.01). All experimental materials showed satisfactory physical-chemical properties to be used as endodontic sealers in clinical practice. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Structure and Bonding in Uranyl(VI) Peroxide and Crown Ether Complexes; Comparison of Quantum Chemical and Experimental Data.

    Science.gov (United States)

    Vallet, Valérie; Grenthe, Ingmar

    2017-12-18

    The structure, chemical bonding, and thermodynamics of alkali ions in M[12-crown-4] + , M[15-crown-5] + , and M[18-crown-6] + , M[UO 2 (O 2 )(OH 2 ) 2 ] + 4,5 , and M[UO 2 (O 2 )(OH)(OH 2 )] n 1-n (n = 4, 5) complexes have been explored by using quantum chemical (QC) calculations at the ab initio level. The chemical bonding has been studied in the gas phase in order to eliminate solvent effects. QTAIM analysis demonstrates features that are very similar in all complexes and typical for electrostatic M-O bonds, but with the M-O bonds in the uranyl peroxide systems about 20 kJ mol -1 stronger than in the corresponding crown ether complexes. The regular decrease in bond strength with increasing M-O bond distance is consistent with predominantly electrostatic contributions. Energy decomposition of the reaction energies in the gas phase and solvent demonstrates that the predominant component of the total attractive (ΔE elec + ΔE orb ) energy contribution is the electrostatic component. There are no steric constraints for coordination of large cations to small rings, because the M + ions are located outside the ring plane, [O n ], formed by the oxygen donors in the ligands; coordination of ions smaller than the ligand cavity results in longer than normal M-O distances or in a change in the number of bonds, both resulting in weaker complexes. The Gibbs energies, enthalpies, and entropies of reaction calculated using the conductor-like screening model, COSMO, to account for solvent effects deviate significantly from experimental values in water, while those in acetonitrile are in much better agreement. Factors that might affect the selectivity are discussed, but our conclusion is that present QC methods are not accurate enough to describe the rather small differences in selectivity, which only amount to 5-10 kJ mol -1 . We can, however, conclude on the basis of QC and experimental data that M[crown ether] + complexes in the strongly coordinating water solvent are of

  19. Experimental study of the natural circulation phenomena

    International Nuclear Information System (INIS)

    Sabundjian, Gaiane; Andrade, Delvonei Alves de; Umbehaun, Pedro E.; Torres, Walmir M.; Castro, Alfredo Jose Alvim de; Belchior Junior, Antonio; Rocha, Ricardo Takeshi Vieira da; Damy, Osvaldo Luiz de Almeida; Torres, Eduardo

    2006-01-01

    The objective of this paper is to study the natural circulation in experimental loops and extend the results to nuclear facilities. New generation of compact nuclear power plants use the natural circulation as cooling and residual heat removal systems in case of accidents or shutdown. Lately the interest in this phenomenon, by scientific community, has increased. The experimental loop, described in this paper, was assembled at Escola Politecnica - USP at the Chemical Engineering Department. It is the goal to generate information to help with the understanding of the one and two phase natural circulation phenomena. Some experiments were performed with different levels of heat power and different flow of the cooling water at the secondary circuit. The data generated from these experiments are going to be used to validate some computational thermal hydraulic codes. Experimental results for one and two phase regimes are presented as well as the proposed model to simulate the flow regimes with the RELAP5 code. (author)

  20. The Role of Attrition and Solids Recovery in a Chemical Looping Combustion Process; Effet de l'attrition et de la recuperation des particules dans le procede de combustion en boucle chimique

    Energy Technology Data Exchange (ETDEWEB)

    Kramp, M.; Thon, A.; Hartge, E.U.; Heinrich, S.; Werther, J. [Institute of Solids Process Engineering and Particle Technology, Hamburg University of Technology, 21071 Hamburg (Germany)

    2011-03-15

    In the present work, the steady-state behavior of a Chemical Looping Combustion process of interconnected fluidized bed reactors is simulated. The simulations have been carried out in two different scales, 50 kWth and 100 MWth. Attrition model derived from small scale laboratory experiments has been employed for the prediction of the process behavior in terms of attrition and Oxygen Carrier loss. Information on Oxygen Carrier characteristics and reaction kinetics were taken from literature. Realistic circulation mass flows of Oxygen Carrier particles are obtained and Oxygen Carrier losses are quantified. The large scale process looses significantly more Oxygen Carrier than the small scale process based on the same amount of thermal energy produced. Incomplete conversion in the air reactor could be identified as a critical point. Another issue is the fuel gas bypassing the Oxygen Carrier particles through bubbles in the large scale process which leads to lowered fuel conversions. The simulations indicate that a similar performance of a pilot scale and a large scale process is not guaranteed due to the scale-up effect on fluid dynamics. Furthermore, the simulations allow an assessment of the influence of the quality of the solids recovery system on the Oxygen Carrier loss. The distribution of the losses between possible origins is investigated and different changes in the solids recovery system are discussed regarding their potential to decrease the Oxygen Carrier loss. For example, the addition of a second-stage cyclone after the air reactor of the large scale process reduces the Oxygen Carrier loss significantly. (authors)

  1. Blind Loop Syndrome

    Science.gov (United States)

    ... of tissue that protrude through the intestinal wall (diverticulosis) Certain medical conditions, including Crohn's disease, radiation enteritis, ... History of radiation therapy to the abdomen Diabetes Diverticulosis of the small intestine Complications A blind loop ...

  2. Diffusion of Wilson loops

    International Nuclear Information System (INIS)

    Brzoska, A.M.; Lenz, F.; Thies, M.; Negele, J.W.

    2005-01-01

    A phenomenological analysis of the distribution of Wilson loops in SU(2) Yang-Mills theory is presented in which Wilson loop distributions are described as the result of a diffusion process on the group manifold. It is shown that, in the absence of forces, diffusion implies Casimir scaling and, conversely, exact Casimir scaling implies free diffusion. Screening processes occur if diffusion takes place in a potential. The crucial distinction between screening of fundamental and adjoint loops is formulated as a symmetry property related to the center symmetry of the underlying gauge theory. The results are expressed in terms of an effective Wilson loop action and compared with various limits of SU(2) Yang-Mills theory

  3. Mashup the OODA Loop

    National Research Council Canada - National Science Library

    Heier, Jeffrey E

    2008-01-01

    ...) processes via the Observe, Orient, Decide, and Act (OODA) Loop concept. As defined by Wikipedia, a mashup is a Website or application that combines the content from more than one source into an integrated presentation...

  4. Dechanneling by dislocation loops

    International Nuclear Information System (INIS)

    Chalant, Gerard.

    1976-09-01

    Ion implantation always induces the creation of dislocation loops. When the damage profile is determined by a backscattering technique, the dechanneling by these loops is implicitely at the origin of these measurements. The dechanneling of alpha particles by dislocation loops produced by the coalescence of quenched-in vacancies in aluminium is studied. The dechanneling and the concentration of loops were determined simultaneously. The dechanneling width around dislocation was found equal to lambda=6A, both for perfect and imperfect loops having a mean diameter d=250A. In the latter case, a dechanneling probability chi=0.34 was determined for the stacking fault, in good agreement with previous determination in gold. A general formula is proposed which takes into account the variation of lambda with the curvature (or the diameter d) of the loops. Finally, by a series of isothermal anneals, the self-diffusion energy ΔH of aluminium was measured. The value obtained ΔH=1.32+-0.10eV is in good agreement with the values obtained by other methods [fr

  5. Effects of metal pollutants on magnetic and chemical properties of soils and plant biomass: experimental studies in Environmental Magnetism

    Science.gov (United States)

    Sapkota, Birendra

    Understanding the interactions and effects of biotic and abiotic factors on magnetic parameter measurements used to assess levels of pollutants requires experimental analysis of potential individual parameters. Using magnetic and chemical measurements, three separate experimental studies were conducted in order to evaluate the separate and combined effects of soil composition, atmospheric exposure, and contaminant levels on soil magnetic susceptibility (MS) measurements, plant growth and metal uptake by plants. Experiment 1 examined the effects of incorporating an artificial Fe-rich contaminant into a synthetic soil on surficial soil magnetic properties and plant growth inside a greenhouse. Periodic measurements of surficial soil MS showed significant decreases in MS values in the three treatments (two levels of Fe-contamination and controls), with the greatest reduction in soils with the most contamination, and the least in controls. Three potential causes were suggested: Fe uptake by plants, magnetic minerals transformation, and downward migration of Fe-particles. Some arguments for the first two causes were discussed; however, the third possibility was separately evaluated in the second and third experiments. In the follow-up study (Experiment 2) conducted to examine the effects of ambient atmospheric pollution on magnetic and chemical properties of soils and plant biomass, the overall surficial soil MS was found to be significantly higher in synthetic soils exposed to a natural atmosphere in comparison to controls placed in a greenhouse. Root biomass samples taken from the exposed soils had much higher trace/heavy metal concentrations. Such increases in soil MS and bioavailability of metals in the exposed soils indicate that atmospheric pollution affected the soil and plants grown in there. Microscopic observations of Fe-rich particles from the post-harvest exposed soil revealed morphologies similar to Fe-containing particulates from power plants and

  6. Experimental study of iron reduction and oxidation mechanisms in a natural clay. Evolution of its physical and chemical properties

    International Nuclear Information System (INIS)

    Bruno, Gerard

    1993-01-01

    Chemical reductions (CBD treatment) on the Fo Ca 7 clay selected as backfilling material for radioactive waste disposal. This sedimentary multi-phased clay material, mainly consists of a mixed-layer kaolinite/smectite and Fe oxy-hydroxides (hematite and goethite). The total Fe content ranges between 6 and 8% of Fe 2 O 3 by weight, with approximately half in the clay fraction and half in the oxy-hydroxides. Experimental results reveal: - Reduction mechanisms: the reduction rate of Fe is inversely proportional to the clay particle size and thus is proportional to the specific surface area. This indicates that the reduction pathway proceeds mainly from the edges to the center of the clay particles. The chemical measurements of Fe 2+ as a function of reduction time reveal the presence of successive reduction rates. Moessbauer and UV-Visible spectroscopic analyses suggest that these successive reduction rates are related to the presence of atom populations that are more or less accessible for reduction. The re-oxidation of Fe in Fo Ca 7 appears incomplete with a hysteresis phenomenon. All these results indicate that the crystallochemical environment of Fe within the structure influences the reduction and the re-oxidation kinetics of the clay. - Fe oxy-hydroxides: these phases, which appear as coatings in the natural material, are preferentially dissolved and removed by the CBD treatment. The removal of such phases induces the disaggregation of the material, especially increasing the proportion of very small particles. - Evolution of reduced clay properties: The removal of Fe oxy-hydroxides induces an increase in the swelling of the clay, whereas the increase in Fe 2+ content decreases the swelling of the clay. The cation exchange capacity increases with increasing Fe 2+ content without changing the smectitic characteristics of the clay. Studying a natural, multi-phased, Fe-poor smectite gives additional information regarding the effects of Fe oxidation state on physical-chemical

  7. Analysis Of Noise In Optical Phase-Locked Loop

    Science.gov (United States)

    Win, Moe Z.; Chen, Chien C.; Scholtz, Robert A.

    1993-01-01

    Report presents theoretical and experimental analysis of noise in coherent optical phase-locked loop. Optical phase-locked loop being considered for use in heterodyne reception of binary pulse-position modulation at data rate of 100 Kb/s in optical communication system in which transmitter also includes frequency-stabilized laser.

  8. Experimental research of the impact of the dosing of chemical reagents on the dynamic behavior of regulation system of cycle chemistry

    Science.gov (United States)

    Yegoshina, O. V.; Bolshakova, N. A.

    2017-11-01

    Organization of reliable chemical control for maintaining cycle chemistry is one of the most important problems to be solved at the present time the design and operation of thermal power plants. To maintain optimal parameters of cycle chemistry are used automated chemical control system and regulation system of dosing chemical reagents. Reliability and stability analyzer readings largely determine the reliability of the water cycle chemistry. Now the most common reagents are ammonia, alkali and film-forming amines. In this paper are presented the results of studies of the impact of concentration and composition of chemical reagents for readings stability of automatic analyzers and transients time of control systems for cycles chemistry. Research of the impact of chemical reagents on the dynamic behavior of regulation system for cycle chemistry was conducted at the experimental facility of the Department of thermal power stations of the Moscow Engineering Institute. This experimental facility is model of the work of regulation system for cycle chemistry close to the actual conditions on the energy facilities CHP. Analysis of results of the impact of chemical reagent on the dynamic behavior of ammonia and film forming amines dosing systems showed that the film-forming amines dosing system is more inertia. This emphasizes the transition process of the system, in which a half times longer dosing of ammonia. Results of the study can be used to improve the monitoring systems of water chemical treatment.

  9. Looping in OLSRv2 in Mobile Ad-Hoc Networks, Loop Suppression and Loop Correction

    Science.gov (United States)

    Speakman, Lee; Owada, Yasunori; Mase, Kenichi

    Transient routing loops have been observed to form in Mobile Ad-hoc Networks running the OLSRv2 proactive link-state routing protocol. The packets falling into loops impact the surrounding network thus degrading throughput even though only a small proportion of the traffic may enter these loops and only for a short time. This becomes significantly more evident when Link Layer Notification is used to catch broken links, inadvertently leading to an increase in the number of loops. Two methods of Loop Detection are introduced and are used to trigger either Loop Suppression by selectively and preemptively discarding the looping packets that are unlikely to reach their destination, or Loop Correction by the notification of the routing protocol to cut the link over which the packet is looping. The newly introduced Loop Suppression and Loop Correction techniques used with Link Layer Notification are shown to significantly increase network performance over plain OLSRv2 and OLSRv2 with Link Layer Notification.

  10. Numerical simulation of a natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Verissimo, Gabriel L.; Moreira, Maria de Lourdes; Faccini, Jose Luiz H., E-mail: gabrielverissimo@poli.ufrj.b, E-mail: malu@ien.gov.b, E-mail: faccini@ien.gov.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    This work presents a numerical simulation of a natural circulation loop using computational fluid dynamics. The simulated loop is an experimental model in a reduced scale of 1:10 of a passive heat removal system typical of advanced PWR reactors. The loop is composed of a heating vessel containing 52 electric heaters, a vertical shell-tube heat exchanger and a column of expansion. The working fluid is distilled water. Initially it was created a tridimensional geometric model of the loop components. After that, it was generated a tridimensional mesh of finite elements in order to calculate the variables of the problem. The boundaries of the numerical simulation were the power of the electric resistances and the cooling flow in the secondary side of the heat exchanger. The initial conditions were the temperature, the pressure and the fluid velocity at the time just before the power has been switched on. The results of this simulation were compared with the experimental data, in terms of the evolution of the temperatures in different locations of the loop, and of the average natural circulation flow as a function of time for a given power. (author)

  11. Formation and some properties of Fe core-shell powders with experimental parameters of the chemical vapor condensation process

    International Nuclear Information System (INIS)

    Kim, J.C.; Kim, S.J.; Kim, Y.D.; Kim, J.S.; Choi, C.J.

    2009-01-01

    Core-shell powders, recently, have aroused interest because of their potential applications in various areas such as electronics, optics, catalysis, ferrofluids, and magnetic data storage. Their unique properties and superior performances are determined by their powder size, shell thickness and surface structure, phase and powder interaction. In this study, carbon-coated Fe core-shell powders were prepared by chemical vapor condensation (CVC) process using Fe metal-organic (Fe(CO) 5 ) precursor and carbon containing carrier gases such as carbon monoxide and methane. Effects of experimental parameters on the properties of the as-produced core-shell powders were studied by X-ray diffractometer, Brunauer-Emitter-Teller analyzer, high resolution transmission electron microscope and X-ray photoelectron spectrometer. The microstructures and phases of the synthesized core-shell powders varied with the decomposition temperature of the precursors and the flow rate of the carrier gases. CVC Fe powders showed intricate long stand-like structure because of intrinsic magnetic properties of Fe.

  12. Kinetics study of solid ammonia borane hydrogen release--modeling and experimental validation for chemical hydrogen storage.

    Science.gov (United States)

    Choi, Young Joon; Rönnebro, Ewa C E; Rassat, Scot; Karkamkar, Abhi; Maupin, Gary; Holladay, Jamie; Simmons, Kevin; Brooks, Kriston

    2014-05-07

    Ammonia borane (AB), NH3BH3, is a promising material for chemical hydrogen storage with 19.6 wt% gravimetric hydrogen capacity of which maximum 16.2 wt% hydrogen can be released via an exothermic thermal decomposition below 200 °C. We have investigated the kinetics of hydrogen release from AB and from an AB-methyl cellulose (AB/MC) composite at temperatures of 160-300 °C using both experiments and modeling. The hydrogen release rate at 300 °C is twice as fast as at 160 °C. The purpose of our study was to show safe hydrogen release without thermal runaway effects and to validate system model kinetics. AB/MC released hydrogen at ∼20 °C lower than neat AB and at a faster release rate in that temperature range. Based on the experimental results, the kinetics equations were revised to better represent the growth and nucleation process during decomposition of AB. We explored two different reactor concepts; auger and fixed bed. The current auger reactor concept turned out to not be appropriate, however, we demonstrated safe self-propagation of the hydrogen release reaction of solid AB/MC in a fixed bed reactor.

  13. Experimental studies on the weathering of chemicals in a field trial to predict their behaviour in case of a spill

    International Nuclear Information System (INIS)

    Mamaca, E.; Merlin, F.X.; Le Floch, S.

    2004-01-01

    Most of the world's production of vegetable oil is transported by sea. In 2001, nearly 850,000 tons of vegetable oil entered and left harbours in France. This trend increases the risk of accidental spills at sea. The physical state of vegetable oil changes when it is spilled at sea, turning this non-toxic product into a pollutant that damages the marine ecosystem. This study demonstrated how vegetable oil could react when spilled at sea. A series of field studies were conducted to obtain experimental data on the behaviour of vegetable oil both on the surface of water and in the water column. Castor oil, soybean oil, oleic acid and dioctylphtalate were released at sea and the dispersion of the oil in the water was monitored with a fluorimeter. Measurements were taken to a depth of 1 metre. Emulsification and viscosity kinetics were monitored. The study showed that the behaviour of the 4 products depends on the nature of the product and weather conditions such as wind and sea surface state. Vegetable oil spilled at sea behaves differently from spilled chemical products in terms of solubility. It was suggested that in the case of an accidental spill at sea, emergency responders should first pump the oil and then use dispersants. 6 refs., 2 tabs., 11 figs

  14. Chemical and Mechanical Properties of Experimental Dental Composites as a Function of Formulation and Postcuring Thermal Treatment

    Directory of Open Access Journals (Sweden)

    Renata A. Esteves

    2018-01-01

    Full Text Available This study evaluated the influence of formulation and thermal treatment on the degree of conversion, fracture toughness, flexural strength, and elastic modulus of experimental composites. Six composites were analyzed at BisGMA : TEGDMA molar ratios of 1 : 1 and 7 : 3 with filler at 30, 50, and 70 wt%. The degree of conversion was analyzed by Fourier transform infrared spectroscopy, fracture toughness was measured using the single-edge notched beam, and flexural strength and elastic modulus were measured with the 3-point bend test. For all tests, one-half of the specimens received thermal treatment at 170°C for 10 min. Data were analyzed by the Kruskal-Wallis or ANOVA/Tukey’s test (α = 5%. The 1 : 1 BisGMA : TEGDMA ratio showed higher properties than the 7 : 3 ratio. Although the material with 70% filler had a conversion lower than the one with 50%, it showed higher mechanical properties. The thermal treatment improved all properties in all materials. Therefore, the use of an equimolar ratio of BisGMA : TEGDMA can be paired with 70 wt% filler to design dental composites that possess increased advantageous physical and chemical properties. Furthermore, the simple and low-cost method of thermal treatment proposed for use in clinical dentistry has been shown to effectively improve the properties of all evaluated materials.

  15. Kinetics Study of Solid Ammonia Borane Hydrogen Release – Modeling and Experimental Validation for Chemical Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong-Joon; Ronnebro, Ewa; Rassat, Scot D.; Karkamkar, Abhijeet J.; Maupin, Gary D.; Holladay, Jamelyn D.; Simmons, Kevin L.; Brooks, Kriston P.

    2014-02-24

    Ammonia borane (AB), NH3BH3, is a promising material for chemical hydrogen storage with 19.6 wt% gravimetric hydrogen capacity of which 16.2 wt% hydrogen can be utilized below 200°C. We have investigated the kinetics of hydrogen release from AB and from an AB-methyl cellulose (AB/MC) composite at temperatures of 160-300°C using both experiments and modeling. The purpose of our study was to show safe hydrogen release without thermal runaway effects and to validate system model kinetics. AB/MC released hydrogen at ~20°C lower than neat AB and at a rate that is two times faster. Based on the experimental results, the kinetics equations were revised to better represent the growth and nucleation process during decomposition of AB. We explored two different reactor concepts; Auger and fixed bed. The current Auger reactor concept turned out to not be appropriate, however, we demonstrated safe self-propagation of the hydrogen release reaction of solid AB/MC in a fixed bed reactor.

  16. PG-100 helium loop in the MR reactor

    International Nuclear Information System (INIS)

    Ponomarev-Stepnoj, N.N.; Yakovlev, V.V.; Tikhonov, N.I.

    1983-01-01

    Main systems and production equipment units of PG-100 helium loop in the MR reactor are described. Possible long-term synchronizing operation of loop and reactor as well as possibility of carrying out life-time tests of spherical fuel elements and materials are shown. Serviceability of spherical fuel elements under conditions similar to the ones of HTGR-50 operation as well as high serviceability of cleanup system accepted for HTGR are verified. Due to low radiation dose the loop is operated without limits, helium losses in the loop don't exceed 0.5%/24 h, taking account of experimental gas sampling

  17. A Comparison of QSAR Based Thermo and Water Solvation Property Prediction Tools and Experimental Data for Selected Traditional Chemical Warfare Agents and Simulants

    Science.gov (United States)

    2014-07-01

    AND EXPERIMENTAL DATA FOR SELECTED TRADITIONAL CHEMICAL WARFARE AGENTS AND SIMULANTS ECBC-TR-1259 Jerry B. Cabalo RESEARCH AND TECHNOLOGY...PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Cabalo , Jerry B. (ECBC); and Knox, Craig K. (Leidos) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT

  18. Free online access to experimental and predicted chemical properties through the EPA’s CompTox Chemistry Dashboard (ACS Spring meeting)

    Science.gov (United States)

    The increasing number and size of public databases is facilitating the collection of chemical structures and associated experimental data for QSAR modeling. However, the performance of QSAR models is highly dependent not only on the modeling methodology, but also on the quality o...

  19. UPTF loop seal tests and their RELAP simulation

    International Nuclear Information System (INIS)

    Tuomainen, M.; Tuunanen, J.

    1997-01-01

    In a pressurized water reactor the loop seals have an effect on the natural circulation. If a loop seal is filled with water it can cause a flow stagnation in the loop during two-phase natural circulation. Also the pressure loss over a filled loop seal is high, which lowers the water level in the core. Tests to investigate the loop seal behaviour were performed on a German Upper Plenum Test Facility (UPTF). The purpose of the tests was to study the amount of water in the loop seal under different steam flow rates. The tests were simulated with RELAP5/MOD3.2. With high steam flow rates the code had problems in simulating the amount of the water remaining in the pump elbow, but in general the agreement between the calculated results and the experimental data was good. (orig.)

  20. Effect of DNA hairpin loops on the twist of planar DNA origami tiles.

    Science.gov (United States)

    Li, Zhe; Wang, Lei; Yan, Hao; Liu, Yan

    2012-01-31

    The development of scaffolded DNA origami, a technique in which a long single-stranded viral genome is folded into arbitrary shapes by hundreds of short synthetic oligonucleotides, represents an important milestone in DNA nanotechnology. Recent findings have revealed that two-dimensional (2D) DNA origami structures based on the original design parameters adopt a global twist with respect to the tile plane, which may be because the conformation of the constituent DNA (10.67 bp/turn) deviates from the natural B-type helical twist (10.4 bp/turn). Here we aim to characterize the effects of DNA hairpin loops on the overall curvature of the tile and explore their ability to control, and ultimately eliminate any unwanted curvature. A series of dumbbell-shaped DNA loops were selectively displayed on the surface of DNA origami tiles with the expectation that repulsive interactions among the neighboring dumbbell loops and between the loops and the DNA origami tile would influence the structural features of the underlying tiles. A systematic, atomic force microscopy (AFM) study of how the number and position of the DNA loops influenced the global twist of the structure was performed, and several structural models to explain the results were proposed. The observations unambiguously revealed that the first generation of rectangular shaped origami tiles adopt a conformation in which the upper right (corner 2) and bottom left (corner 4) corners bend upward out of the plane, causing linear superstructures attached by these corners to form twisted ribbons. Our experimental observations are consistent with the twist model predicted by the DNA mechanical property simulation software CanDo. Through the systematic design and organization of various numbers of dumbbell loops on both surfaces of the tile, a nearly planar rectangular origami tile was achieved. © 2011 American Chemical Society

  1. Comprehensive experimental and theoretical study of chemical equilibria in the reacting system of the tert-amyl methyl ether synthesis.

    Science.gov (United States)

    Heintz, Andreas; Kapteina, Simon; Verevkin, Sergey P

    2007-09-20

    The chemical equilibrium of the reactive system (methanol+isoamylenesmethyl tert-amyl ether) was studied in the temperature range 298-393 K in the liquid phase using the method of sealed ampoules as well as in the gaseous phase using a tubular flow reactor in the temperature range 355-378 K. In both cases, a cation exchanger Amberlist-15 was used as a heterogeneous catalyst. The reactive system of the methyl tert-amyl ether synthesis exhibits a strong nonideal behavior of the mixture compounds in the liquid phase. The knowledge of the activity coefficients is required in order to obtain the thermodynamic equilibrium constants Ka. Two well-established procedures, UNIFAC and COSMO-RS, have been used to assess activity coefficients of the reaction participants in the liquid phase. Thermodynamic equilibrium constants KP measured in the gaseous phase together with the vapor pressures of the pure compounds have been used to obtain Ka in the liquid phase on a consistent experimental basis in order to check the results obtained from the UNIFAC and COSMO-RS methods. Enthalpies of reactions DeltarH degrees of the methyl tert-amyl ether synthesis reaction in the gaseous and in the liquid phase were obtained from temperature dependences of the corresponding thermodynamic equilibrium constants. Consistency of the experimental data of DeltarH degrees was verified with help of enthalpies of formation and enthalpies of vaporization of methyl tert-amyl ether, methanol, and methyl-butenes, available from the literature. For the sake of comparison, high-level ab initio calculations of the reaction participants have been performed using the Gaussian-03 program package. Absolute electronic energy values, normal frequencies (harmonic approximation), and moments of inertia of the molecules have been obtained using G2(MP2), G3(MP2), and G3 levels. Using these results, calculated equilibrium constants and the enthalpy of reaction of the methyl tert-amyl ether synthesis in the gaseous phase

  2. Microfluidic photoinduced chemical oxidation for Ru(bpy)33+chemiluminescence - A comprehensive experimental comparison with on-chip direct chemical oxidation.

    Science.gov (United States)

    Kadavilpparampu, Afsal Mohammed; Al Lawati, Haider A J; Suliman, Fakhr Eldin O

    2017-08-05

    For the first time, the analytical figures of merit in detection capabilities of the very less explored photoinduced chemical oxidation method for Ru(bpy) 3 2+ CL has been investigated in detail using 32 structurally different analytes. It was carried out on-chip using peroxydisulphate and visible light and compared with well-known direct chemical oxidation approaches using Ce(IV). The analytes belong to various chemical classes such as tertiary amine, secondary amine, sulphonamide, betalactam, thiol and benzothiadiazine. Influence of detection environment on CL emission with respect to method of oxidation was evaluated by changing the buffers and pH. The photoinduced chemical oxidation exhibited more universal nature for Ru(bpy) 3 2+ CL in detection towards selected analytes. No additional enhancers, reagents, or modification in instrumental configuration were required. Wide detectability and enhanced emission has been observed for analytes from all the chemical classes when photoinduced chemical oxidation was employed. Some of these analytes are reported for the first time under photoinduced chemical oxidation like compounds from sulphonamide, betalactam, thiol and benzothiadiazine class. On the other hand, many of the selected analytes including tertiary and secondary amines such as cetirizine, azithromycin fexofenadine and proline did not produced any analytically useful CL signal (S/N=3 or above for 1μgmL -1 analyte) under chemical oxidation. The most fascinating observations was in the detection limits; for example ofloxacin was 15 times more intense with a detection limit of 5.81×10 -10 M compared to most lowest ever reported 6×10 -9 M. Earlier, penicillamine was detected at 0.1μgmL -1 after derivatization using photoinduced chemical oxidation, but in this study, we improved it to 5.82ngmL -1 without any prior derivatization. The detection limits of many other analytes were also found to be improved by several orders of magnitude under photoinduced

  3. Closing global material loops

    DEFF Research Database (Denmark)

    Prosman, Ernst-Jan; Wæhrens, Brian Vejrum; Liotta, Giacomo

    2017-01-01

    Replacing virgin materials with waste materials, a practice known as Industrial Symbiosis (IS), has been identified as a key strategy for closing material loops. This article adopts a critical view on geographic proximity and external coordinators – two key enablers of IS. By ‘uncovering’ a case ...... for geographic proximity and external coordinators. In doing so, our insights into firm-level challenges of long-distance IS exchanges contribute to closing global material loops by increasing the number of potential circular pathways....

  4. Closed Loop Subspace Identification

    Directory of Open Access Journals (Sweden)

    Geir W. Nilsen

    2005-07-01

    Full Text Available A new three step closed loop subspace identifications algorithm based on an already existing algorithm and the Kalman filter properties is presented. The Kalman filter contains noise free states which implies that the states and innovation are uneorre lated. The idea is that a Kalman filter found by a good subspace identification algorithm will give an output which is sufficiently uncorrelated with the noise on the output of the actual process. Using feedback from the output of the estimated Kalman filter in the closed loop system a subspace identification algorithm can be used to estimate an unbiased model.

  5. Experimental Study of the Effect for Water Depth on the Mass Transfer of Passive Solar Still Chemical Solutions

    Directory of Open Access Journals (Sweden)

    Fayadh M. Abed

    2018-01-01

    Full Text Available An experimental study on a passive solar distiller in the Tikrit city on (latitude line"34 36o north, longitude line "45 43o east, and purpose of that study to raise the efficiency and productivity of the solar distiller. And then design the monoclinic solar distiller and add reflector plate and a solar concentrate. The Practical tests were conducted at a rate of every half-hour from the beginning of February to the beginning of the month of June. The study began by comparing the solar distiller that contain the concentrates and without contain it. Then study the influence of adding coal and chemical solutions, like blue Thymol solution and blue bromophenol solution to see the additions effect on the productivity and efficiency of distiller, and also The study was conducted to see the effect of the water depth on the productivity of distiller with take four water depths within the basin are (2,1.5,1,0.5 cm of water. The tests were conducted in weather conditions close. and the results of the study, That distilled added his concentrates improved its productivity by 46% and efficiency increases 43% with non-use of concentrates, and coal increased efficiency by 36% and productivity improved up to 38%, the addition of  blue Thymol solution increases the efficiency by 19% and productivity by 16%, as well as bromophenol solution  increase productivity by 23% and improve efficiency by 25%, when comparing the additions found that the best one is coal. Through the study of the depth of the water show that increases productivity and efficiency by reducing the depth of the water in the basin distiller. DOI: http://dx.doi.org/10.25130/tjes.24.2017.13

  6. A Detailed Experimental and Theoretical Investigation on the Chemical and Physical Behavior of Gold Nanoparticles under X-ray Radiation

    Science.gov (United States)

    Cheng, Neal

    A detailed investigation into the interaction between highly ionizing x-ray radiation and nanomaterials was performed. To begin, a theoretical model of the interactions of the system was created as an attempt to understand the relationship between the nanomaterial and the radiation-generated species. The model spans from the physical regime (10-10 s), during which the chemical species generated from radiolytic cleavage of water diffuses and reacts. A combination of methods was used in the simulation: Monte Carlo, Brownian diffusion, and kinetic rate equations. Several experimental systems were created for the purpose of testing the radio-enhancing effects of nanomaterials and the validity of the model: Firstly, the effects of localized energy deposition by gold nanoparticles were examined in a system consisting of 3 nm gold nanoparticles conjugated to DNA. In this system, single-strand breaks on DNA were used to probe the spatial distribution of energy nanometers around the nanoparticle. A comparison of the local energy deposition by gold nanoparticles versus global energy deposition by water was examined using the model. An additional 150% in DNA strand breaks was observed at 100 mM Tris (2-Amino-2-hydroxymethyl-propane-1,3-diol, represents 5nm diffusion distance), yet according to the model, the energy deposition of 10 gold nanoparticles on a strand of DNA accounts for only an additional 20%. Several explanations were given, such as the different reactivity of radical at short distance, the cross-linking of multiple DNA to a single nanoparticle, and geometric configuration of DNA. Secondly, the effect of remote energy deposition was examined in a system consisting of gold nanotubules and free-floating DNA, containing a composition of 50 wt.% Au/50 wt.% H2O. There was no localized energy deposition due to non-conjugation and a maximum enhancement of 1400% was found at 10 mM Tris, which was inconsistent with the expected enhancement of ˜14000%. The result was

  7. Chemical Looping Pilot Plant Results Using a Nickel-Based Oxygen Carrier Résultats de l’expérimentation sur un pilote opérant en boucle chimique avec un matériau transporteur d’oxygène à base de nickel

    Directory of Open Access Journals (Sweden)

    Pröll T.

    2011-04-01

    Full Text Available A chemical looping pilot plant was designed, built and operated with a design fuel power of 120 kW (lower heating value, natural gas. The system consists of two Circulating Fluidized Bed (CFB reactors. Operating results are presented and evaluated for a highly reactive nickel-based oxygen carrier, total system inventory 65 kg. The performance in fuel conversion achieved is in the range of 99.8% (CH4 conversion and 92% (CO2 yield. In chemical looping reforming operation, it can be reported that thermodynamic equilibrium is reached in the fuel reactor and that all oxygen is absorbed in the air reactor as soon as the global stoichiometric air/fuel ratio is below 1 and the air reactor temperature is 900°C or more. Even though pure natural gas (98.6 vol.% CH4 without steam addition was fed to the fuel reactor, no carbon formation has been found as long as the global stoichiometric air/fuel ratio was larger than 0.4. Based on the experimental findings and on the general state of the art, it is concluded that niche applications such as industrial steam generation from natural gas or CO2-ready coupled production of H2 and N2 can be interesting pathways for immediate scale-up of the technology. Un pilote d’étude de la combustion en boucle chimique d’une puissance thermique de 120 kW a été dimensionné, construit et opéré. Il est constitué de deux lits circulants interconnectés. Les résultats d’opération qui sont présentés ont été obtenus avec un matériau transporteur d’oxygène très réactif à base de nickel. L’inventaire total du matériau est de 65 kg dans le pilote. La conversion du méthane atteinte est voisine de 99,8 % et le rendement en CO2 est de 92 %. Lorsqu’on opère en mode de reformage, l’équilibre thermodynamique est atteint dans le réacteur fioul. Tout l’oxygène est capté dans le réacteur air dès que le rapport stoechiométrique entre l’air et le méthane est inférieur à 1 et que la temp

  8. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    1998-01-01

    Full Text Available The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained are: (i The computation of the physical spectra of geometrical quantities such as area and volume, which yields quantitative predictions on Planck-scale physics. (ii A derivation of the Bekenstein-Hawking black hole entropy formula. (iii An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, over-completeness of the loop basis, implementation of reality conditions have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  9. Justification by Infinite Loops

    NARCIS (Netherlands)

    Peijnenburg, A.J.M.; Atkinson, David

    2010-01-01

    In an earlier paper we have shown that a proposition can have a well-defined probability value, even if its justification consists of an infinite linear chain. In the present paper we demonstrate that the same holds if the justification takes the form of a closed loop. Moreover, in the limit that

  10. Improving Loop Dependence Analysis

    DEFF Research Database (Denmark)

    Jensen, Nicklas Bo; Karlsson, Sven

    2017-01-01

    Programmers can no longer depend on new processors to have significantly improved single-thread performance. Instead, gains have to come from other sources such as the compiler and its optimization passes. Advanced passes make use of information on the dependencies related to loops. We improve th...

  11. Operation of the hot test loop facilities

    International Nuclear Information System (INIS)

    Cheong, Moon Ki; Park, Choon Kyeong; Won, Soon Yeon; Yang, Sun Kyu; Cheong, Jang Whan; Cheon, Se Young; Song, Chul Hwa; Jeon, Hyeong Kil; Chang, Suk Kyu; Jeong, Heung Jun; Cho, Young Ro; Kim, Bok Duk; Min, Kyeong Ho

    1994-12-01

    The objective of this project is to obtain the available experimental data and to develop the measuring techniques through taking full advantage of the facilities. The facilities operated by the thermal hydraulics department have been maintained and repaired in order to carry out the thermal hydraulics tests necessary for providing the available data. The performance tests for double grid type bottom end piece which was improved on the debris filtering effectivity were performed using the PWR-Hot Test Loop. The CANDU-Hot Test Loop was operated to carry out the pressure drop tests and strength tests of fuel. The Cold Test Loop was used to obtain the local velocity data in subchannel within fuel bundle and to understand the characteristic of pressure drop required for improving the nuclear fuel and to develop the advanced measuring techniques. RCS Loop, which is used to measure the CHF, is presently under design and construction. B and C Loop is designed and constructed to assess the automatic depressurization safety system behavior. 4 tabs., 79 figs., 7 refs. (Author) .new

  12. Fish toxicity tests with mixtures of more than two chemicals: a proposal for a quantitative approach and experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Koenemann, H.

    1981-01-01

    The problem of the toxic action of mixtures of many chemicals has been studied. Starting with the classification of Plackett and Hewlett, the types of mixtures for which toxicity can be predicted is discussed. A Mixture Toxicity Index (MTI) has been proposed as a quantification of the result of mixture toxicity experiments. Toxicity experiments with guppies have been conducted, using 6 mixtures of 3--50 chemicals. The toxicity of mixtures of simple similarly acting chemicals could be predicted by Concentration Addition. The concentrations of the separate chemicals in a mixture of 50 compounds giving 50% mortality, were 0.02 X LC50.

  13. Public control of environmental health hazards (clinical and experimental studies of distal axonopathy--a frequent form of brain and nerve damage produced by environmental chemical hazards)

    Energy Technology Data Exchange (ETDEWEB)

    Schaumburg, H.H.; Spencer, P.S.

    1979-01-01

    Clinical and pathological studies of the peripheral and central nervous system degeneration (distal dying-back axonopathy) in humans and experimental animals produced by acrylamide monomer and certain hydrocarbon compounds are summarized. The human distal axonopathies include: many of the naturally occurring, genetically determined system disorders/ certain nutritional disorders/ uremic neuropathy/ the neuropathies associated with some malignancies/ and the toxic neuropathies induced by industrial chemicals. The irreversible, subclinical, and clinical effects of distal axonopathies on the human central nervous system are examined. A morphological rationale for previously enigmatic clinical phenomena in the human toxic neuropathies is presented. Neuropathology is potentially useful in the screening of chemicals for neurotoxicity. (7 photos, 24 references)

  14. The chemical component dictionary: complete descriptions of constituent molecules in experimentally determined 3D macromolecules in the Protein Data Bank.

    Science.gov (United States)

    Westbrook, John D; Shao, Chenghua; Feng, Zukang; Zhuravleva, Marina; Velankar, Sameer; Young, Jasmine

    2015-04-15

    The Chemical Component Dictionary (CCD) is a chemical reference data resource that describes all residue and small molecule components found in Protein Data Bank (PDB) entries. The CCD contains detailed chemical descriptions for standard and modified amino acids/nucleotides, small molecule ligands and solvent molecules. Each chemical definition includes descriptions of chemical properties such as stereochemical assignments, chemical descriptors, systematic chemical names and idealized coordinates. The content, preparation, validation and distribution of this CCD chemical reference dataset are described. The CCD is updated regularly in conjunction with the scheduled weekly release of new PDB structure data. The CCD and amino acid variant reference datasets are hosted in the public PDB ftp repository at ftp://ftp.wwpdb.org/pub/pdb/data/monomers/components.cif.gz, ftp://ftp.wwpdb.org/pub/pdb/data/monomers/aa-variants-v1.cif.gz, and its mirror sites, and can be accessed from http://wwpdb.org. jwest@rcsb.rutgers.edu. Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Conceptional design of test loop for FIV in fuel bundle

    Energy Technology Data Exchange (ETDEWEB)

    Sim, W. G.; Yang, J. S.; Kim, S. W. [Hannam Univ., Taejeon (Korea)

    2001-01-01

    It is urgent to develop the analytical model for the structural/mechanical integrity of fuel rod. In general, it is not easy to develop a pure analytical model. Occasionally, experimental results have been utilized for the model. Because of this reason, it is required to design proper test loop. Using the optimized test loop, with the optimized test loop, the dynamic behaviour of the rod will be evaluated and the critical flow velocity, which the rod loses the stability in, will be measured for the design of the rod. To verify the integrity of the fuel rod, it is required to evaluate the dynamic behaviour and the critical flow velocity with the test loop. The test results will be utilized to the design of the rod. Generally, the rod has a ground vibration due to turbulence in wide range of flow velocity and the amplitude of vibration becomes larger by the resonance, in a range of the velocity where occurs vortex. The rod loses stability in critical flow velocity caused by fluid-elastic instability. For the purpose of the present work to perform the conceptional design of the test loop, it is necessary (1) to understand the mechanism of the flow-induced vibration and the related experimental coefficients, (2) to evaluate the existing test loops for improving the loop with design parameters and (3) to decide the design specifications of the major equipments of the loop. 35 refs., 23 figs., 2 tabs. (Author)

  16. Loop Quantum Cosmology

    Directory of Open Access Journals (Sweden)

    Bojowald Martin

    2008-07-01

    Full Text Available Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time.

  17. Loop Quantum Cosmology.

    Science.gov (United States)

    Bojowald, Martin

    2008-01-01

    Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time. Supplementary material is available for this article at 10.12942/lrr-2008-4.

  18. Closing the loop.

    Science.gov (United States)

    Dassau, E; Atlas, E; Phillip, M

    2010-02-01

    The dream of closing the loop is actually the dream of creating an artificial pancreas and freeing the patients from being involved with the care of their own diabetes. Insulin-dependent diabetes (type 1) is a chronic incurable disease which requires constant therapy without the possibility of any 'holidays' or insulin-free days. It means that patients have to inject insulin every day of their life, several times per day, and in order to do it safely they also have to measure their blood glucose levels several times per day. Patients need to plan their meals, their physical activities and their insulin regime - there is only very small room for spontaneous activities. This is why the desire for an artificial pancreas is so strong despite the fact that it will not cure the diabetic patients. Attempts to develop a closed-loop system started in the 1960s but never got to a clinical practical stage of development. In recent years the availability of continuous glucose sensors revived those efforts and stimulated the clinician and researchers to believe that closing the loop might be possible nowadays. Many papers have been published over the years describing several different ideas on how to close the loop. Most of the suggested systems have a sensing arm that measures the blood glucose repeatedly or continuously, an insulin delivery arm that injects insulin upon command and a computer that makes the decisions of when and how much insulin to deliver. The differences between the various published systems in the literature are mainly in their control algorithms. However, there are also differences related to the method and site of glucose measurement and insulin delivery. SC glucose measurements and insulin delivery are the most studied option but other combinations of insulin measurements and glucose delivery including intravascular and intraperitoneal (IP) are explored. We tried to select recent publications that we believe had influenced and inspired people interested

  19. Loop Quantum Cosmology

    Directory of Open Access Journals (Sweden)

    Bojowald Martin

    2005-12-01

    Full Text Available Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical space-time inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding space-time is then modified. One particular realization is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. Main effects are introduced into effective classical equations which allow to avoid interpretational problems of quantum theory. They give rise to new kinds of early universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function which allows to extend space-time beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of space-time arising in loop quantum gravity and its application to cosmology sheds new light on more general issues such as time.

  20. LoopIng: a template-based tool for predicting the structure of protein loops.

    KAUST Repository

    Messih, Mario Abdel

    2015-08-06

    Predicting the structure of protein loops is very challenging, mainly because they are not necessarily subject to strong evolutionary pressure. This implies that, unlike the rest of the protein, standard homology modeling techniques are not very effective in modeling their structure. However, loops are often involved in protein function, hence inferring their structure is important for predicting protein structure as well as function.We describe a method, LoopIng, based on the Random Forest automated learning technique, which, given a target loop, selects a structural template for it from a database of loop candidates. Compared to the most recently available methods, LoopIng is able to achieve similar accuracy for short loops (4-10 residues) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has the advantage of being very fast (on average: 1 min/loop).www.biocomputing.it/loopinganna.tramontano@uniroma1.itSupplementary data are available at Bioinformatics online.

  1. Sandia Sodium Purification Loop (SNAPL) description and operations manual

    International Nuclear Information System (INIS)

    Acton, R.U.; Weatherbee, R.L.; Smith, L.A.; Mastin, F.L.; Nowotny, K.E.

    1985-08-01

    Sandia's Sodium Purification Loop was constructed to purify sodium for fast reactor safety experiments. An oxide impurity of less than 10 parts per million is required by these in-pile experiments. Commercial, reactor grade sodium is purchased in 180 kg drums. The sodium is melted and transferred into the unit. The unit is of a loop design and purification is accomplished by ''cold trapping.'' Sodium purified in this loop has been chemically analysed at one part per million oxygen by weight. 5 refs., 22 figs., 7 tabs

  2. The QED vacuum polarization function at four loops and the anomalous magnetic moment at five loops

    International Nuclear Information System (INIS)

    Baikov, P.

    2013-07-01

    The anomalous moment of the muon is one of the most fundamental observables. It has been measured experimentally with a very high precision and on theory side the contributions from perturbative QED have been calculated up to five-loop level by numerical methods. Contributions to the muon anomalous magnetic moment from certain diagram classes are also accessible by alternative methods. In this paper we present the evaluation of contributions to the QCD corrections due to insertions of the vacuum polarization function at five-loop level.

  3. From data point timelines to a well curated data set, data mining of experimental data and chemical structure data from scientific articles, problems and possible solutions.

    Science.gov (United States)

    Ruusmann, Villu; Maran, Uko

    2013-07-01

    The scientific literature is important source of experimental and chemical structure data. Very often this data has been harvested into smaller or bigger data collections leaving the data quality and curation issues on shoulders of users. The current research presents a systematic and reproducible workflow for collecting series of data points from scientific literature and assembling a database that is suitable for the purposes of high quality modelling and decision support. The quality assurance aspect of the workflow is concerned with the curation of both chemical structures and associated toxicity values at (1) single data point level and (2) collection of data points level. The assembly of a database employs a novel "timeline" approach. The workflow is implemented as a software solution and its applicability is demonstrated on the example of the Tetrahymena pyriformis acute aquatic toxicity endpoint. A literature collection of 86 primary publications for T. pyriformis was found to contain 2,072 chemical compounds and 2,498 unique toxicity values, which divide into 2,440 numerical and 58 textual values. Every chemical compound was assigned to a preferred toxicity value. Examples for most common chemical and toxicological data curation scenarios are discussed.

  4. Loop-loop interactions govern multiple steps in indole-3-glycerol phosphate synthase catalysis.

    Science.gov (United States)

    Zaccardi, Margot J; O'Rourke, Kathleen F; Yezdimer, Eric M; Loggia, Laura J; Woldt, Svenja; Boehr, David D

    2014-03-01

    Substrate binding, product release, and likely chemical catalysis in the tryptophan biosynthetic enzyme indole-3-glycerol phosphate synthase (IGPS) are dependent on the structural dynamics of the β1α1 active-site loop. Statistical coupling analysis and molecular dynamic simulations had previously indicated that covarying residues in the β1α1 and β2α2 loops, corresponding to Arg54 and Asn90, respectively, in the Sulfolobus sulfataricus enzyme (ssIGPS), are likely important for coordinating functional motions of these loops. To test this hypothesis, we characterized site mutants at these positions for changes in catalytic function, protein stability and structural dynamics for the thermophilic ssIGPS enzyme. Although there were only modest changes in the overall steady-state kinetic parameters, solvent viscosity and solvent deuterium kinetic isotope effects indicated that these amino acid substitutions change the identity of the rate-determining step across multiple temperatures. Surprisingly, the N90A substitution had a dramatic effect on the general acid/base catalysis of the dehydration step, as indicated by the loss of the descending limb in the pH rate profile, which we had previously assigned to Lys53 on the β1α1 loop. These changes in enzyme function are accompanied with a quenching of ps-ns and µs-ms timescale motions in the β1α1 loop as measured by nuclear magnetic resonance studies. Altogether, our studies provide structural, dynamic and functional rationales for the coevolution of residues on the β1α1 and β2α2 loops, and highlight the multiple roles that the β1α1 loop plays in IGPS catalysis. Thus, substitution of covarying residues in the active-site β1α1 and β2α2 loops of indole-3-glycerol phosphate synthase results in functional, structural, and dynamic changes, highlighting the multiple roles that the β1α1 loop plays in enzyme catalysis and the importance of regulating the structural dynamics of this loop through noncovalent

  5. On some properties of conjugacy closed loops

    International Nuclear Information System (INIS)

    Adeniran, John Olusola

    2002-07-01

    It is shown that central loops are not conjugacy closed loops but instead are loops of units in their loop algebras that are conjugacy closed. It is also shown that certain inner mappings of a conjugacy closed loop are nuclear. Some invariants of left conjugacy closed loops are obtained. (author)

  6. Shortening a loop can increase protein native state entropy.

    Science.gov (United States)

    Gavrilov, Yulian; Dagan, Shlomi; Levy, Yaakov

    2015-12-01

    Protein loops are essential structural elements that influence not only function but also protein stability and folding rates. It was recently reported that shortening a loop in the AcP protein may increase its native state conformational entropy. This effect on the entropy of the folded state can be much larger than the lower entropic penalty of ordering a shorter loop upon folding, and can therefore result in a more pronounced stabilization than predicted by polymer model for loop closure entropy. In this study, which aims at generalizing the effect of loop length shortening on native state dynamics, we use all-atom molecular dynamics simulations to study how gradual shortening a very long or solvent-exposed loop region in four different proteins can affect their stability. For two proteins, AcP and Ubc7, we show an increase in native state entropy in addition to the known effect of the loop length on the unfolded state entropy. However, for two permutants of SH3 domain, shortening a loop results only with the expected change in the entropy of the unfolded state, which nicely reproduces the observed experimental stabilization. Here, we show that an increase in the native state entropy following loop shortening is not unique to the AcP protein, yet nor is it a general rule that applies to all proteins following the truncation of any loop. This modification of the loop length on the folded state and on the unfolded state may result with a greater effect on protein stability. © 2015 Wiley Periodicals, Inc.

  7. Progress in design and development of series liquid lithium-lead expeirmental loops in China

    International Nuclear Information System (INIS)

    Wu Yican; Huang Qunying; Zhu Zhiqiang; Gao Sheng; Song Yong; Li Chunjing; Peng Lei; Liu Shaojun; Wu qingsheng; Liu Songlin; Chen Hongli; Bai Yunqing; Jin Ming; Lv Ruojun; Wang Weihua; Guo Zhihui; Chen Yaping; Ling Xinzhen; Zhang Maolian; Wang Yongliang; Wu Zhaoyang; Wang Hongyan

    2009-01-01

    Liquid LiPb (lithium-lead) experimental loops are the important platforms to investigate the key technologies of liquid LiPb breeder blankets for fusion reactors. Based on the development strategy for liquid LiPb breeder blankets, the technologies development of liquid LiPb experimental loops have been explored by the FDS Team for years, and a series of LiPb experimental loops named DRAGON have been designed and developed, which have independence intellectual property and multi-functional parameters. In this paper, the development route suggestion of Chinese LiPb experimental loops was elaborated, and some information for the senes experimental loops were introduced, such as the design principles, structural features, functions and related experimental researches, etc. (authors)

  8. Quenching phenomena in natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Umekawa, Hisashi; Ozawa, Mamoru [Kansai Univ., Osaka (Japan); Ishida, Naoki [Daihatsu Motor Company, Osaka (Japan)

    1995-09-01

    Quenching phenomena has been investigated experimentally using circulation loop of liquid nitrogen. During the quenching under natural circulation, the heat transfer mode changes from film boiling to nucleate boiling, and at the same time flux changes with time depending on the vapor generation rate and related two-phase flow characteristics. Moreover, density wave oscillations occur under a certain operating condition, which is closely related to the dynamic behavior of the cooling curve. The experimental results indicates that the occurrence of the density wave oscillation induces the deterioration of effective cooling of the heat surface in the film and the transition boiling regions, which results in the decrease in the quenching velocity.

  9. Quenching phenomena in natural circulation loop

    International Nuclear Information System (INIS)

    Umekawa, Hisashi; Ozawa, Mamoru; Ishida, Naoki

    1995-01-01

    Quenching phenomena has been investigated experimentally using circulation loop of liquid nitrogen. During the quenching under natural circulation, the heat transfer mode changes from film boiling to nucleate boiling, and at the same time flux changes with time depending on the vapor generation rate and related two-phase flow characteristics. Moreover, density wave oscillations occur under a certain operating condition, which is closely related to the dynamic behavior of the cooling curve. The experimental results indicates that the occurrence of the density wave oscillation induces the deterioration of effective cooling of the heat surface in the film and the transition boiling regions, which results in the decrease in the quenching velocity

  10. Experimental paradigm for in-lab proxy aquatic studies under conditions of static, non flow through chemical exposures

    Science.gov (United States)

    Endocrine disrupting chemicals (EDCs) such as 17α ethynylestradiol (EE2), 17β estradiol (E2), estrone (E1) and para-nonylphenol (NP) have been measured in wastewater treatment plant effluents, surface waters, sediments and sludge, and have been shown to induce liver-sp...

  11. Some considerations in the splitting of interstitial frank loops formed by irradiation

    International Nuclear Information System (INIS)

    Seshan, K.; Grilhe, J.; Washburn, J.

    1975-05-01

    The splitting of interstitial loops formed by irradiation is considered in detail. It is shown that they may split to form obtuse--angled single shear faults on the intersecting (111) planes. A detailed description of the splitting is given in which the interstitial Frank loop is viewed as being made up of perfect dislocation loop and two shears. The detailed description is then considered in the context of the formation of complex loops as are observed in quenching and irradiation studies. Experimentally observed geometries are explained viz, triangular loops within hexagonal ones etc. The nucleation of a DC' loop in complex interstitial loop formation is shown to be feasible. DC' has the magnitude of a perfect dislocation loop and encloses an intrinsic shear

  12. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  13. Novel protocol for the chemical synthesis of crustacean hyperglycemic hormone analogues--an efficient experimental tool for studying their functions.

    Directory of Open Access Journals (Sweden)

    Alessandro Mosco

    Full Text Available The crustacean Hyperglycemic Hormone (cHH is present in many decapods in different isoforms, whose specific biological functions are still poorly understood. Here we report on the first chemical synthesis of three distinct isoforms of the cHH of Astacus leptodactylus carried out by solid phase peptide synthesis coupled to native chemical ligation. The synthetic 72 amino acid long peptide amides, containing L- or D-Phe³ and (Glp¹, D-Phe³ were tested for their biological activity by means of homologous in vivo bioassays. The hyperglycemic activity of the D-isoforms was significantly higher than that of the L-isoform, while the presence of the N-terminal Glp residue had no influence on the peptide activity. The results show that the presence of D-Phe³ modifies the cHH functionality, contributing to the diversification of the hormone pool.

  14. Novel Protocol for the Chemical Synthesis of Crustacean Hyperglycemic Hormone Analogues — An Efficient Experimental Tool for Studying Their Functions

    Science.gov (United States)

    Mosco, Alessandro; Zlatev, Vientsislav; Guarnaccia, Corrado; Pongor, Sándor; Campanella, Antonella; Zahariev, Sotir; Giulianini, Piero G.

    2012-01-01

    The crustacean Hyperglycemic Hormone (cHH) is present in many decapods in different isoforms, whose specific biological functions are still poorly understood. Here we report on the first chemical synthesis of three distinct isoforms of the cHH of Astacus leptodactylus carried out by solid phase peptide synthesis coupled to native chemical ligation. The synthetic 72 amino acid long peptide amides, containing L- or D-Phe3 and (Glp1, D-Phe3) were tested for their biological activity by means of homologous in vivo bioassays. The hyperglycemic activity of the D-isoforms was significantly higher than that of the L-isoform, while the presence of the N-terminal Glp residue had no influence on the peptide activity. The results show that the presence of D-Phe3 modifies the cHH functionality, contributing to the diversification of the hormone pool. PMID:22253873

  15. An experimental investigation on mass transfer in presence of chemical reactions on a graphite cylinder in crossflow

    International Nuclear Information System (INIS)

    Ogawa, M.; Stauch, B.; Moormann, R.; Katscher, W.

    1985-11-01

    In connection with analyses of hypothetical massive air ingress accidents in HTGR experiments on mass transfer and in-pore diffusion with homogeneous and heterogeneous chemical reactions were performed. Two BLMR runs and two runs in an intermediate regime between BLMR and IPDR were executed at atmospheric pressures, Reynolds numbers ranging from 533 to 2490, and cylinder temperatures from 848 0 C to 1120 0 C. The nuclear grade graphite cylinder having a diameter of 100 mm and a porosity of 21.2% was corroded in a nitrogen gas flow containing approximately 5% oxygen. Mean and local mass transfer coefficients and corrosion rates were obtained to examine the influences of the chemical reactions on the mass transfer. As a result it can be concluded that the chemical reactions and small changes in shape do not significantly influence the mass transfer under conditions to be expected in air ingress accidents and that thus the analogy between heat and mass transfer can be used for safety calculations. (orig./HP)

  16. Open Experimentation on Phenomena of Chemical Reactions via the Learning Company Approach in Early Secondary Chemistry Education

    Science.gov (United States)

    Beck, Katharina; Witteck, Torsten; Eilks, Ingo

    2010-01-01

    Presented is a case study on the implementation of open and inquiry-type experimentation in early German secondary chemistry education. The teaching strategy discussed follows the learning company approach. Originally adopted from vocational education, the learning company method is used to redirect lab-oriented classroom practice towards a more…

  17. 3-D thermalhydraulics flow effects on wall concentration gradient profiles of corrosion/precipitation phenomena in LBE loop fittings

    International Nuclear Information System (INIS)

    Armbya, Narain; Li, Guanjun; Chen, Yitung; Moujaes, Samir

    2004-01-01

    Work is ongoing at UNLV to provide a computer simulation framework that will characterize the behavior and effect of thermalhydraulics on the corrosion/precipitation chemical kinetics processes that take place on the inside surfaces of an LBE flow loop. To that end detailed models are being constructed to study these effects first in several expected loop fittings such as sudden expansion and tee-fittings. The typical flow rates chosen for these simulations are typical of design criteria chosen for the loop with Re numbers expected around 200,000 and the usual axial temperature profiles which are being characterized in the DELTA loop at LANL. STAR-CD is the simulation package used to make these predictions which include detailed 3-D velocity, temperature and concentration gradient profiles of the corrosion/precipitation on the inner surface of these fittings initially. The different predicted variables from these simulations indicate that special attention needs to be placed when designing loops with these fittings especially in the regions of sudden velocity changes and stagnation zones. These wall gradients can determine eventually the expected longevity of these fittings in an LBE flow environment. Presently though very little experimental data exists that would be suitable to corroborate the simulation results. Graphs of concentration gradient v/s distance from the inlet of these fittings were plotted. Eventually these individual fitting models will become part of an overall closed loop that will yield more realistic core concentration values and hence more realistic wall gradient values which are dependent on these core values. (author)

  18. Modeling of compact loop antennas

    International Nuclear Information System (INIS)

    Baity, F.W.

    1987-01-01

    A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively-tuned resonant double loop (RDL) antennas the model treats stub-tuned resonant double loop antennas. Calculations using the model have been compared with measurements on full-scale mockups of resonant double loop antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and for the Compact Ignition Tokamak

  19. Innovative hybrid pile oscillator technique in the Minerve reactor: open loop vs. closed loop

    Science.gov (United States)

    Geslot, Benoit; Gruel, Adrien; Bréaud, Stéphane; Leconte, Pierre; Blaise, Patrick

    2018-01-01

    Pile oscillator techniques are powerful methods to measure small reactivity worth of isotopes of interest for nuclear data improvement. This kind of experiments has long been implemented in the Mineve experimental reactor, operated by CEA Cadarache. A hybrid technique, mixing reactivity worth estimation and measurement of small changes around test samples is presented here. It was made possible after the development of high sensitivity miniature fission chambers introduced next to the irradiation channel. A test campaign, called MAESTRO-SL, took place in 2015. Its objective was to assess the feasibility of the hybrid method and investigate the possibility to separate mixed neutron effects, such as fission/capture or scattering/capture. Experimental results are presented and discussed in this paper, which focus on comparing two measurements setups, one using a power control system (closed loop) and another one where the power is free to drift (open loop). First, it is demonstrated that open loop is equivalent to closed loop. Uncertainty management and methods reproducibility are discussed. Second, results show that measuring the flux depression around oscillated samples provides valuable information regarding partial neutron cross sections. The technique is found to be very sensitive to the capture cross section at the expense of scattering, making it very useful to measure small capture effects of highly scattering samples.

  20. Innovative hybrid pile oscillator technique in the Minerve reactor: open loop vs. closed loop

    Directory of Open Access Journals (Sweden)

    Geslot Benoit

    2018-01-01

    Full Text Available Pile oscillator techniques are powerful methods to measure small reactivity worth of isotopes of interest for nuclear data improvement. This kind of experiments has long been implemented in the Mineve experimental reactor, operated by CEA Cadarache. A hybrid technique, mixing reactivity worth estimation and measurement of small changes around test samples is presented here. It was made possible after the development of high sensitivity miniature fission chambers introduced next to the irradiation channel. A test campaign, called MAESTRO-SL, took place in 2015. Its objective was to assess the feasibility of the hybrid method and investigate the possibility to separate mixed neutron effects, such as fission/capture or scattering/capture. Experimental results are presented and discussed in this paper, which focus on comparing two measurements setups, one using a power control system (closed loop and another one where the power is free to drift (open loop. First, it is demonstrated that open loop is equivalent to closed loop. Uncertainty management and methods reproducibility are discussed. Second, results show that measuring the flux depression around oscillated samples provides valuable information regarding partial neutron cross sections. The technique is found to be very sensitive to the capture cross section at the expense of scattering, making it very useful to measure small capture effects of highly scattering samples.

  1. Experimental study and modelling of physico-chemical mechanisms of clay-concrete interactions in the radioactive waste geological disposal context

    International Nuclear Information System (INIS)

    Dauzeres, A.

    2010-09-01

    These research works are carried out as part of the radioactive wastes geological disposal feasibility study. The current option developed by Andra, includes several cementitious materials in contact with the surrounding Callovo-Oxfordian (COX) (an argillite). Concretes and argillite present very different pore solutions (ionic concentrations and pH). Controlled by the concentrations differences, the aqueous species diffusion in the solids generates chemical and physical disturbances. This study is based on experimental, analytical and numerical works, in order to identify the mechanisms controlling the clayey environment influence on cementitious materials. (author)

  2. Vortex loops and Majoranas

    International Nuclear Information System (INIS)

    Chesi, Stefano; Jaffe, Arthur; Loss, Daniel; Pedrocchi, Fabio L.

    2013-01-01

    We investigate the role that vortex loops play in characterizing eigenstates of interacting Majoranas. We give some general results and then focus on ladder Hamiltonian examples as a test of further ideas. Two methods yield exact results: (i) A mapping of certain spin Hamiltonians to quartic interactions of Majoranas shows that the spectra of these two examples coincide. (ii) In cases with reflection-symmetric Hamiltonians, we use reflection positivity for Majoranas to characterize vortices in the ground states. Two additional methods suggest wider applicability of these results: (iii) Numerical evidence suggests similar behavior for certain systems without reflection symmetry. (iv) A perturbative analysis also suggests similar behavior without the assumption of reflection symmetry

  3. Dynamic PID loop control

    International Nuclear Information System (INIS)

    Pei, L.; Klebaner, A.; Theilacker, J.; Soyars, W.; Martinez, A.; Bossert, R.; DeGraff, B.; Darve, C.

    2011-01-01

    The Horizontal Test Stand (HTS) SRF Cavity and Cryomodule 1 (CM1) of eight 9-cell, 1.3GHz SRF cavities are operating at Fermilab. For the cryogenic control system, how to hold liquid level constant in the cryostat by regulation of its Joule-Thompson JT-valve is very important after cryostat cool down to 2.0 K. The 72-cell cryostat liquid level response generally takes a long time delay after regulating its JT-valve; therefore, typical PID control loop should result in some cryostat parameter oscillations. This paper presents a type of PID parameter self-optimal and Time-Delay control method used to reduce cryogenic system parameters oscillation.

  4. Closed loop reflux system

    International Nuclear Information System (INIS)

    De Witt, R.; Jepson, B.E.; Schwind, R.A.

    1975-01-01

    Sulfur isotopes are continuously separated and enriched using a closed loop reflux system wherein sulfur dioxide (SO 2 ) is reacted with sodium hydroxide (NaOH) or the like to form sodium hydrogen sulfite (NaHSO 3 ). Heavier sulfur isotopes are preferentially attracted to the NaHSO 3 , and subsequently reacted with sulfuric acid (H 2 SO 4 ) forming sodium hydrogen sulfate (NaHSO 4 ) and SO 2 gas, which contains increased concentrations of the heavier sulfur isotopes. This heavy isotope enriched SO 2 gas is subsequently separated and the NaHSO 4 is reacted with NaOH to form sodium sulfate (Na 2 SO 4 ), which is subsequently decomposed in an electrodialysis unit to form the NaOH and H 2 SO 4 components, which are used in the aforesaid reactions thereby effecting sulfur isotope separation and enrichment without objectionable loss of feed materials. (U.S.)

  5. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    2008-07-01

    Full Text Available The problem of describing the quantum behavior of gravity, and thus understanding quantum spacetime, is still open. Loop quantum gravity is a well-developed approach to this problem. It is a mathematically well-defined background-independent quantization of general relativity, with its conventional matter couplings. Today research in loop quantum gravity forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained so far are: (i The computation of the spectra of geometrical quantities such as area and volume, which yield tentative quantitative predictions for Planck-scale physics. (ii A physical picture of the microstructure of quantum spacetime, characterized by Planck-scale discreteness. Discreteness emerges as a standard quantum effect from the discrete spectra, and provides a mathematical realization of Wheeler’s “spacetime foam” intuition. (iii Control of spacetime singularities, such as those in the interior of black holes and the cosmological one. This, in particular, has opened up the possibility of a theoretical investigation into the very early universe and the spacetime regions beyond the Big Bang. (iv A derivation of the Bekenstein–Hawking black-hole entropy. (v Low-energy calculations, yielding n-point functions well defined in a background-independent context. The theory is at the roots of, or strictly related to, a number of formalisms that have been developed for describing background-independent quantum field theory, such as spin foams, group field theory, causal spin networks, and others. I give here a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  6. Loop Quantum Gravity.

    Science.gov (United States)

    Rovelli, Carlo

    2008-01-01

    The problem of describing the quantum behavior of gravity, and thus understanding quantum spacetime , is still open. Loop quantum gravity is a well-developed approach to this problem. It is a mathematically well-defined background-independent quantization of general relativity, with its conventional matter couplings. Today research in loop quantum gravity forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained so far are: (i) The computation of the spectra of geometrical quantities such as area and volume, which yield tentative quantitative predictions for Planck-scale physics. (ii) A physical picture of the microstructure of quantum spacetime, characterized by Planck-scale discreteness. Discreteness emerges as a standard quantum effect from the discrete spectra, and provides a mathematical realization of Wheeler's "spacetime foam" intuition. (iii) Control of spacetime singularities, such as those in the interior of black holes and the cosmological one. This, in particular, has opened up the possibility of a theoretical investigation into the very early universe and the spacetime regions beyond the Big Bang. (iv) A derivation of the Bekenstein-Hawking black-hole entropy. (v) Low-energy calculations, yielding n -point functions well defined in a background-independent context. The theory is at the roots of, or strictly related to, a number of formalisms that have been developed for describing background-independent quantum field theory, such as spin foams, group field theory, causal spin networks, and others. I give here a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  7. Experimental study and modeling of a high-temperature solar chemical reactor for hydrogen production from methane cracking

    Energy Technology Data Exchange (ETDEWEB)

    Abanades, Stephane; Flamant, Gilles [Processes, Materials, and Solar Energy Laboratory, CNRS (PROMES-CNRS, UPR 8521), 7 Rue du Four Solaire, 66120 Odeillo Font-Romeu (France)

    2007-07-15

    A high-temperature fluid-wall solar reactor was developed for the production of hydrogen from methane cracking. This laboratory-scale reactor features a graphite tubular cavity directly heated by concentrated solar energy, in which the reactive flowing gas dissociates to form hydrogen and carbon black. The solar reactor characterization was achieved with: (a) a thorough experimental study on the reactor performance versus operating conditions and (b) solar reactor modeling. The results showed that the conversion of CH{sub 4} and yield of H{sub 2} can exceed 97% and 90%, respectively, and these depend strongly on temperature and on fluid-wall heat transfer and reaction surface area. In addition to the experimental study, a 2D computational model coupling transport phenomena was developed to predict the mapping of reactor temperature and of species concentration, and the reaction extent at the outlet. The model was validated and kinetics of methane decomposition were identified from simulations and comparison to experimental results. (author)

  8. Experimental Investigation Of Microbially Induced Corrosion Of Test Samples And Effect Of Self-assembled Hydrophobic Monolayers. Exposure Of Test Samples To Continuous Microbial Cultures, Chemical Analysis, And Biochemical Studies

    CERN Document Server

    Laurinavichius, K S

    1998-01-01

    Experimental Investigation Of Microbially Induced Corrosion Of Test Samples And Effect Of Self-assembled Hydrophobic Monolayers. Exposure Of Test Samples To Continuous Microbial Cultures, Chemical Analysis, And Biochemical Studies

  9. Loop quantum cosmology: Recent progress

    Indian Academy of Sciences (India)

    Aspects of the full theory of loop quantum gravity can be studied in a simpler context by reducing to symmetric models like cosmological ones. This leads to several applications where loop effects play a significant role when one is sensitive to the quantum regime. As a consequence, the structure of and the approach to ...

  10. RCD+: Fast loop modeling server.

    Science.gov (United States)

    López-Blanco, José Ramón; Canosa-Valls, Alejandro Jesús; Li, Yaohang; Chacón, Pablo

    2016-07-08

    Modeling loops is a critical and challenging step in protein modeling and prediction. We have developed a quick online service (http://rcd.chaconlab.org) for ab initio loop modeling combining a coarse-grained conformational search with a full-atom refinement. Our original Random Coordinate Descent (RCD) loop closure algorithm has been greatly improved to enrich the sampling distribution towards near-native conformations. These improvements include a new workflow optimization, MPI-parallelization and fast backbone angle sampling based on neighbor-dependent Ramachandran probability distributions. The server starts by efficiently searching the vast conformational space from only the loop sequence information and the environment atomic coordinates. The generated closed loop models are subsequently ranked using a fast distance-orientation dependent energy filter. Top ranked loops are refined with the Rosetta energy function to obtain accurate all-atom predictions that can be interactively inspected in an user-friendly web interface. Using standard benchmarks, the average root mean squared deviation (RMSD) is 0.8 and 1.4 Å for 8 and 12 residues loops, respectively, in the challenging modeling scenario in where the side chains of the loop environment are fully remodeled. These results are not only very competitive compared to those obtained with public state of the art methods, but also they are obtained ∼10-fold faster. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  11. Experimental results of 2-propanol dehydrogenation with a falling-liquid film reactor for solar chemical heat pump; Solar chemical heat pump ni okeru ryuka ekimakushiki 2-propanol bunkai hanno jikken

    Energy Technology Data Exchange (ETDEWEB)

    Doi, T.; Tanaka, T.; Ando, Y.; Takashima, T. [Electrotechnical Laboratory, Tsukuba (Japan); Koike, M.; Kamoshida, J. [Shibaura Institute of Technology, Tokyo (Japan)

    1997-11-25

    A solar chemical heat pump is intended to attempt multi-purposed effective utilization of solar energy by raising low temperature solar heat of about 100 degC to 150 to 200 degC by utilizing chemical reactions. The chemical heat pump under the present study uses a 2-propanol (IPA)/acetone/hydrogen system which can utilize low-temperature solar heat and has large temperature rising degree. It was found from the result of experiments and analyses that IPA dehydrogenation reaction can improve more largely the heat utilization rate in using a falling-liquid film reactor than using a liquid phase suspended system. As an attempt to improve further the heat utilization rate, this paper reports the result of experimental discussions on inclination angles of a reaction vessel and feed liquid flow rate which would affect the fluid condition of the liquid film. As a result of the experiments, the initial deterioration in the catalyst has settled in about 15 hours, and its activity has decreased to about 60% of the initial activity. It was made clear that the influence of the inclination angle of the reaction vessel on the reaction is small. 5 refs., 7 figs.

  12. Development of a closed and open loop solar tracker technology

    Directory of Open Access Journals (Sweden)

    Aurélio Gouvêa Melo

    2017-05-01

    Full Text Available Solar energy is among the renewable energy sources that received greater addition in installed capacity. However, it accounts for a small fraction of the energy matrix of most countries. Electric energy generation by solar systems can be improved through tracking. This work aimed to develop and compare a closed and an open loop solar tracking system. The closed loop system was developed using Light Dependent Resistors. An algorithm was developed for the open loop tracker as a function of the geometric relation between the sun and the photovoltaic module. A simulation was run to compare this algorithm with a system using tracking at fixed time intervals, for clear sky conditions, with different tracking parameters and for five different latitudes. No significant difference was observed between the proposed open loop tracking algorithm and the fixed time interval algorithm for the tracking parameters evaluated. The open and closed loop solar tracking systems were compared experimentally in Rio das Ostras, Brazil (22.49 °S 41.92° W. An average gain of 28.5% was observed for the open loop tracking system over a latitude tilted system and 33.0% for the closed loop tracking system.

  13. Free convection in a partially submerged fluid loop

    International Nuclear Information System (INIS)

    Britt, T.E.; Wood, D.C.

    1982-01-01

    Several natural convection loop systems are studied in order to determine the operational characteristics for a multiple loop container which is used to cool failed nuclear reactor assemblies. Both analytical and experimental studies were undertaken to examine flow in both circular and rectangular flow loops. It was found that when a circular loop is heated at the bottom and cooled at the top, recirculation cells form at all input power fluxes. At fluxes between 0.1 W/cm 2 and 0.7 W/cm 2 the cells caused flow oscillations and reversals. With the circular loop heated from the side, no recirculation cells were observed at the power fluxes up to 1.5 W/cm. Boiling did not occur in the circular loop. For a rectangular loop heated and cooled on its vertical sides, no recirculation cells or flow reversals were seen. At input power fluxes above 1.2 W/cm 2 , periodic boiling in the heated side caused flow oscillations

  14. The free-energy cost of interaction between DNA loops.

    Science.gov (United States)

    Huang, Lifang; Liu, Peijiang; Yuan, Zhanjiang; Zhou, Tianshou; Yu, Jianshe

    2017-10-03

    From the viewpoint of thermodynamics, the formation of DNA loops and the interaction between them, which are all non-equilibrium processes, result in the change of free energy, affecting gene expression and further cell-to-cell variability as observed experimentally. However, how these processes dissipate free energy remains largely unclear. Here, by analyzing a mechanic model that maps three fundamental topologies of two interacting DNA loops into a 4-state model of gene transcription, we first show that a longer DNA loop needs more mean free energy consumption. Then, independent of the type of interacting two DNA loops (nested, side-by-side or alternating), the promotion between them always consumes less mean free energy whereas the suppression dissipates more mean free energy. More interestingly, we find that in contrast to the mechanism of direct looping between promoter and enhancer, the facilitated-tracking mechanism dissipates less mean free energy but enhances the mean mRNA expression, justifying the facilitated-tracking hypothesis, a long-standing debate in biology. Based on minimal energy principle, we thus speculate that organisms would utilize the mechanisms of loop-loop promotion and facilitated tracking to survive in complex environments. Our studies provide insights into the understanding of gene expression regulation mechanism from the view of energy consumption.

  15. Experimental setup for producing tungsten coated graphite tiles using plasma enhanced chemical vapor deposition technique for fusion plasma applications

    International Nuclear Information System (INIS)

    Chauhan, Sachin Singh; Sharma, Uttam; Choudhary, K.K.; Sanyasi, A.K.; Ghosh, J.; Sharma, Jayshree

    2013-01-01

    Plasma wall interaction (PWI) in fusion grade machines puts stringent demands on the choice of materials in terms of high heat load handling capabilities and low sputtering yields. Choice of suitable material still remains a challenge and open topic of research for the PWI community. Carbon fibre composites (CFC), Beryllium (Be), and Tungsten (W) are now being considered as first runners for the first wall components of future fusion machines. Tungsten is considered to be one of the suitable materials for the job because of its superior properties than carbon like low physical sputtering yield and high sputter energy threshold, high melting point, fairly high re-crystallization temperature, low fuel retention capabilities, low chemical sputtering with hydrogen and its isotopes and most importantly the reparability with various plasma techniques both ex-situ and in-situ. Plasma assisted chemical vapour deposition is considered among various techniques as the most preferable technique for fabricating tungsten coated graphite tiles to be used as tokamak first wall and target components. These coated tiles are more favourable compared to pure tungsten due to their light weight and easier machining. A system has been designed, fabricated and installed at SVITS, Indore for producing tungsten coated graphite tiles using Plasma Enhanced Chemical Vapor Deposition (PE-CVD) technique for Fusion plasma applications. The system contains a vacuum chamber, a turbo-molecular pump, two electrodes, vacuum gauges, mass analyzer, mass flow controllers and a RF power supply for producing the plasma using hydrogen gas. The graphite tiles will be put on one of the electrodes and WF6 gas will be inserted in a controlled manner in the hydrogen plasma to achieve the tungsten-coating with WF6 dissociation. The system is integrated at SVITS, Indore and a vacuum of the order of 3*10 -6 is achieved and glow discharge plasma has been created to test all the sub-systems. The system design with

  16. Experimental Study of the Effect for Water Depth on the Mass Transfer of Passive Solar Still Chemical Solutions

    OpenAIRE

    Fayadh M. Abed; Dalaf S. mahmood

    2018-01-01

    An experimental study on a passive solar distiller in the Tikrit city on (latitude line"34 36o north, longitude line "45 43o east), and purpose of that study to raise the efficiency and productivity of the solar distiller. And then design the monoclinic solar distiller and add reflector plate and a solar concentrate. The Practical tests were conducted at a rate of every half-hour from the beginning of February to the beginning of the month of June. The study began by comparing the solar disti...

  17. Higher dimensional loop quantum cosmology

    International Nuclear Information System (INIS)

    Zhang, Xiangdong

    2016-01-01

    Loop quantum cosmology (LQC) is the symmetric sector of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogeneous cosmological model in n + 1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n + 1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n + 1 dimensional model and the 3 + 1 dimensional one. Our model serves as a first example of higher dimensional loop quantum cosmology and offers the possibility to investigate quantum gravity effects in higher dimensional cosmology. (orig.)

  18. Leptogenesis from loop effects in curved spacetime

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Jamie I.; Shore, Graham M. [Department of Physics, Swansea University,Singleton Park, Swansea, SA2 8PP (United Kingdom)

    2016-04-05

    We describe a new mechanism — radiatively-induced gravitational leptogenesis — for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove this is forbidden in flat space by CPT and translation symmetry. This generates a curvature-dependent chemical potential for leptons, allowing a matter-antimatter asymmetry to be generated in thermal equilibrium in the early Universe. The time-dependent dynamics necessary for leptogenesis is provided by the interaction of the virtual self-energy cloud of the leptons with the expanding curved spacetime background, which violates the strong equivalence principle and allows a distinction between matter and antimatter. We show here how this mechanism is realised in a particular BSM theory, the see-saw model, where the quantum loops involve the heavy sterile neutrinos responsible for light neutrino masses. We demonstrate by explicit computation of the relevant two-loop Feynman diagrams how the size of the radiative corrections relevant for leptogenesis becomes enhanced by increasing the mass hierarchy of the sterile neutrinos, and show how the induced lepton asymmetry may be sufficiently large to play an important rôle in determining the baryon-to-photon ratio of the Universe.

  19. Quantum chemical modeling of the reaction path of chorismate mutase based on the experimental substrate/product complex.

    Science.gov (United States)

    Burschowsky, Daniel; Krengel, Ute; Uggerud, Einar; Balcells, David

    2017-06-01

    Chorismate mutase is a well-known model enzyme, catalyzing the Claisen rearrangement of chorismate to prephenate. Recent high-resolution crystal structures along the reaction coordinate of this enzyme enabled computational analyses at unprecedented detail. Using quantum chemical simulations, we investigated how the catalytic reaction mechanism is affected by electrostatic and hydrogen-bond interactions. Our calculations showed that the transition state (TS) was mainly stabilized electrostatically, with Arg90 playing the leading role. The effect was augmented by selective hydrogen-bond formation to the TS in the wild-type enzyme, facilitated by a small-scale local induced fit. We further identified a previously underappreciated water molecule, which separates the negative charges during the reaction. The analysis includes the wild-type enzyme and a non-natural enzyme variant, where the catalytic arginine was replaced with an isosteric citrulline residue.

  20. Simulations of magnetic hysteresis loops for dual layer recording media

    Science.gov (United States)

    Fal, T. J.; Plumer, M. L.; Whitehead, J. P.; Mercer, J. I.; van Ek, J.; Srinivasan, K.

    2013-05-01

    A Kinetic Monte-Carlo algorithm is applied to examine MH loops of dual-layer magnetic recording media at finite temperature and long time scales associated with typical experimental measurements. In contrast with standard micromagnetic simulations, which are limited to the ns-μs time regime, our approach allows for the direct calculation of magnetic configurations over periods from minutes to years. The model is used to fit anisotropy and coupling parameters to experimental data on exchange-coupled composite media which are shown to deviate significantly from standard micromagnetic results. Sensitivities of the loops to anisotropy, inter-layer exchange coupling, temperature, and sweep rate are examined.

  1. Tritium analysis in natural waters: experimental characteristics of the electrolitic enrichment system of the Chemical Department - Sao Carlos Federal University

    International Nuclear Information System (INIS)

    Mozeto, A.A.; Fontanetti, A.R.

    1986-01-01

    The working conditions of a system for low-level tritium analyses in natural waters were determined using eletrolytic enrichment and liquid scintillation counting techniques. The system installed at the Departamento de Quimica - UFScar is characterized by the following experimental parameters: (a) sample volume reduction factor during eletrolysis = 16.7; (b) tritium recovery factor = 80%; (c) tritium enrichment factor = 13.4; (d) counting efficiency = 12.5%; (e) background level = 11.5 cpm; (f) counting time per sample = 500 minutes; (g) sensitivity = 8.3 TU/cpm; (h) lower detection limit = 3.6 TU + - 50% and (i) analytical capacity = 30 samples/month. It is also discussed the suitability of the analytical system in terms of rain and ground water samples as well. (Author) [pt

  2. Experimental and computational approaches to evaluate the environmental mitigation effect in narrow spaces by noble metal chemical addition (NMCA)

    International Nuclear Information System (INIS)

    Shimizu, Ryosuke; Ota, Nobuyuki; Nagase, Makoto; Aizawa, Motohiro; Ishida, Kazushige; Wada, Yoichi

    2014-01-01

    The environmental mitigation effect of NMCA in a narrow space was evaluated by experimental and computational approaches. In the experiment at 8 MPa and 553K, T-tube whose branched line had a narrow space was prepared, and the Zr electrodes were set in the branched line at certain intervals, which were 1, 3, 5, 7, 9, 11, 15 and 29 cm from the opening section of the branched line. Electrochemical corrosion potential (ECP) at the tip of the branched narrow space varied in response to the water chemistry in the main line which was at right angle with the branched line. Computational fluid dynamics (CFD) analysis reproduced the experimental results. It was also confirmed by CFD analysis that the ingress of water from the main line into the narrow space was accelerated by cavity flow and thermal convection. By CFD analysis in a thermal sleeve of actual plant condition, which had a narrow space, the concentration of dissolved oxygen at a tip of the thermal sleeve reached at 250 ppb within 300 sec, which was the same concentration of the main line. Noble metal deposition on the surface of the thermal sleeve was evaluated by mass transfer model. Noble metal deposition was the largest near the opening section of the branched line, and gradually decreased toward the tip section. In light of the consumption of dissolved oxygen in the branched line, noble metal deposition in the thermal sleeve was sufficient to reduce the ECP. It was expected that NMCA could mitigate the corrosion environment in the thermal sleeve. (author)

  3. Energetics analysis of interstitial loops in single-phase concentrated solid-solution alloys

    Science.gov (United States)

    Wang, Xin-Xin; Niu, Liang-Liang; Wang, Shaoqing

    2018-04-01

    Systematic energetics analysis on the shape preference, relative stability and radiation-induced segregation of interstitial loops in nickel-containing single-phase concentrated solid-solution alloys have been conducted using atomistic simulations. It is shown that the perfect loops prefer rhombus shape for its low potential energy, while the Frank faulted loops favor ellipse for its low potential energy and the possible large configurational entropy. The decrease of stacking fault energy with increasing compositional complexity provides the energetic driving force for the formation of faulted loops, which, in conjunction with the kinetic factors, explains the experimental observation that the fraction of faulted loops rises with increasing compositional complexity. Notably, the kinetics is primarily responsible for the absence of faulted loops in nickel-cobalt with a very low stacking fault energy. We further demonstrate that the simultaneous nickel enrichment and iron/chromium depletion on interstitial loops can be fully accounted for by their energetics.

  4. Electron microscope image contrast from small dislocation loops

    International Nuclear Information System (INIS)

    Holmes, S.M.; Eyre, B.L.; English, C.A.; Perrin, R.C.

    1979-01-01

    The theoretical study of image contrast from small finite dislocation loops in an isotropic BCC crystal, reported in parts I and II, has been extended to include non-edge loops. Computer image simulation has again been used to study the influence of loop normal, n, Burger's vector, b, diffraction vector, g, and image plane normal, z, on the distribution of black-white intensities in images from loops located in layer 1, i.e. within 0.25 xisub(g) of the surface, where xisub(g) is the extinction distance for the diffracting vector g. As before, the choice and range of parameters have been determined by the authors' interest in radiation damage in BCC molybdenum. The main conclusion from a survey of non-edge perfect loop images is that modifications are predicted to the images from edge loops on going to the non-edge configuration, but that in the majority of cases the scheme of image classification introduced for edge loops based on /g.b/ is still appropriate. Generally, the modifications to the edge images take the form of some skewing of the black-white lobes or rotation of the black-white interface. In particular, it was found that, firstly, the images where /g.b/ > 1 always retain their characteristic interface structure between the black and white lobes. Secondly, the g.b = 0 images from loops with b normal to z may be distorted significantly from the symmetrical 'butterfly' obtained from pure edge loops and, thirdly, for some specific combinations of g, b, n and z, difficulty is encountered in distinguishing between modified g.b = 0 and 0 < /g.b/ < 1 images. Lastly, the application of these results to the experimental determination of b and n is discussed. (author)

  5. Conceptual, experimental and computational approaches to support performance assessment of hydrology and chemical transport at Yucca Mountain

    International Nuclear Information System (INIS)

    Narasimhan, T.N. Wang, J.S.Y.

    1992-07-01

    The authors of this report have been participating in the Sandia National Laboratory's hydrologic performance assessment of the Yucca Mountain, Nevada, since 1983. The scope of this work is restricted to the unsaturated zone at Yucca Mountain and to technical questions about hydrology and chemical transport. The issues defined here are not to be confused with the elaborate hierarchy of issues that forms the framework of the US Department of Energy plans for characterizing the site (DOE, 1989). The overall task of hydrologic performance assessment involves issues related to hydrology, geochemistry, and energy transport in a highly heterogeneous natural geologic system which will be perturbed in a major way by the disposal activity. Therefore, a rational evaluation of the performance assessment issues must be based on an integrated appreciation of the aforesaid interacting processes. Accordingly, a hierarchical approach is taken in this report, proceeding from the statement of the broad features of the site that make it the site for intensive studies and the rationale for disposal strategy, through the statement of the fundamental questions that need to be answered, to the identification of the issues that need resolution. Having identified the questions and issues, the report then outlines the tasks to be undertaken to resolve the issues. The report consists essentially of two parts. The first part deals with the definition of issues summarized above. The second part summarizes the findings of the authors between 1983 and 1989 under the activities of the former Nevada Nuclear Waste Storage Investigations (NNWSI) and the current YMP

  6. BOOK REVIEW: A First Course in Loop Quantum Gravity A First Course in Loop Quantum Gravity

    Science.gov (United States)

    Dittrich, Bianca

    2012-12-01

    Students who are interested in quantum gravity usually face the difficulty of working through a large amount of prerequisite material before being able to deal with actual quantum gravity. A First Course in Loop Quantum Gravity by Rodolfo Gambini and Jorge Pullin, aimed at undergraduate students, marvellously succeeds in starting from the basics of special relativity and covering basic topics in Hamiltonian dynamics, Yang Mills theory, general relativity and quantum field theory, ending with a tour on current (loop) quantum gravity research. This is all done in a short 173 pages! As such the authors cannot cover any of the subjects in depth and indeed this book should be seen more as a motivation and orientation guide so that students can go on to follow the hints for further reading. Also, as there are many subjects to cover beforehand, slightly more than half of the book is concerned with more general subjects (special and general relativity, Hamiltonian dynamics, constrained systems, quantization) before the starting point for loop quantum gravity, the Ashtekar variables, are introduced. The approach taken by the authors is heuristic and uses simplifying examples in many places. However they take care in motivating all the main steps and succeed in presenting the material pedagogically. Problem sets are provided throughout and references for further reading are given. Despite the shortness of space, alternative viewpoints are mentioned and the reader is also referred to experimental results and bounds. In the second half of the book the reader gets a ride through loop quantum gravity; the material covers geometric operators and their spectra, the Hamiltonian constraints, loop quantum cosmology and, more broadly, black hole thermodynamics. A glimpse of recent developments and open problems is given, for instance a discussion on experimental predictions, where the authors carefully point out the very preliminary nature of the results. The authors close with an

  7. Elaboration of an open air loop design

    International Nuclear Information System (INIS)

    Mezrahi, A.

    1980-09-01

    The design of an open air loop is presented. The accessories for this design were selected based on calculations using our conditions and realities and afterward teorical calculations were developed for the behavior of the fluid, in this case the air, inside the test section, considering it as hollow cylinder. A computer program was worked out, starting from the data of the design, using known values for the fluid and empirical correlations, aiming the prediction of the experimental results. All the achieved results as well as the comparison between the values found in usage are presented in this work. (Author) [pt

  8. Experimental determination and chemical modelling of radiolytic processes at the spent fuel/water interface. Long contact time experiments

    International Nuclear Information System (INIS)

    We report on the last experimental and modelling results of a research programme that started in 1995, corresponding in that case to the long contact time experiments. The aim of this programme has been to understand the processes that control the radiolytic generation of oxidants and reductants at the spent fuel water interface and their consequences for spent fuel stability and radionuclide release. The results of this work have been reported in different papers and technical reports during the last decade. In this series, well controlled dissolution experiments of PWR Ringhals spent fuel fragments in an initially anoxic closed system and by using different solution compositions have been carried out, the experiments have been opened after a long time period (between 1.5 and 3 years), samples have been taken and gas and solution analyses have been performed. The results indicate the following: Hydrogen and oxygen concentrations follow the same trend, an initial increase of the concentration of both compounds with time until they reach a steady state that indicates an overall balance of all the radiolytic species generated in the system. Hydrogen peroxide data show in general an initial decrease with time until it reaches a steady state for a given solution composition. This confirms the overall balance of the generated radiolytic species. The experimental data shows that uranium dissolution is controlled by the oxidation of the UO 2 matrix in 10 mM bicarbonate solutions while in the rest of the tests carried out at lower or in the absence of carbonate, uranium in the aqueous phase is governed by the precipitation of schoepite. These processes control the co-dissolution of most of the analysed radionuclides, including Sr, Cs, Mo, Tc and Np while not a clear dependency is found for Pu, Y, and Nd suggesting that other processes are governing the concentration of these radionuclides in the aqueous phase. Kinetic modelling has been performed with data from experiments

  9. BMN correlators by loop equations

    International Nuclear Information System (INIS)

    Eynard, Bertrand; Kristjansen, Charlotte

    2002-01-01

    In the BMN approach to N=4 SYM a large class of correlators of interest are expressible in terms of expectation values of traces of words in a zero-dimensional gaussian complex matrix model. We develop a loop-equation based, analytic strategy for evaluating such expectation values to any order in the genus expansion. We reproduce the expectation values which were needed for the calculation of the one-loop, genus one correction to the anomalous dimension of BMN-operators and which were earlier obtained by combinatorial means. Furthermore, we present the expectation values needed for the calculation of the one-loop, genus two correction. (author)

  10. Thermal, chemical, and mass transport processes induced in abyssal sediments by the emplacement of nuclear wastes: Experimental and modelling results

    International Nuclear Information System (INIS)

    McVey, D.F.; Erickson, K.L.; Seyfried, W.E. Jr.

    1983-01-01

    In this chapter the authors discuss the current status of heat and mass transport studies in the marine red clay sediments that are being considered as a nuclear waste isolation medium and review analytical and experimental studies. Calculations based on numerical models indicate that for a maximum allowable sediment-canister interface temperatures of 200 0 to 250 0 C, the sediment can absorb about 1.5kW initial power from waste buried 30 m in the sediment in a canister that is 3 m long and 0.3 m in diameter. The resulting fluid displacement due to convections is found to be small, less than 1 m. Laboratory studies of the geochemical effects induced by heating sediment-seawater mixtures indicate that the canister and waste form should be designed to resist a hot, relatively acidic oxidizing environment. Since the thermally altered sediment volume of about 5.5 m/sup 3/ is small relative to the sediment volume overlying the canister, the acid and oxidizing conditions should significantly affect the properties of the far field only if thermodiffusional process (Soret effect) prove to be significant. If thermodiffusional effects are important, however, near-field chemistry will differ considerably from that predicted from results of constant temperature sediment-seawater interaction experiments

  11. Syn vs Anti Carboxylic Acids in Hybrid Peptides: Experimental and Theoretical Charge Density and Chemical Bonding Analysis.

    Science.gov (United States)

    Pal, Rumpa; Reddy, M B Madhusudana; Dinesh, B; Venkatesha, Manjunath A; Grabowsky, Simon; Jelsch, Christian; Guru Row, Tayur N

    2018-04-12

    A comparative study of syn vs anti carboxylic acids in hybrid peptides based on experimental electron density studies and theoretical calculations shows that, in the anti form, all three bond angles surrounding C carboxyl of the -COOH group are close to ∼120°, as expected for a C-sp 2 atom, whereas in the syn form, the ∠C α -C(O)-O hydroxyl angle is significantly smaller by 5-10°. The oxygen atom in the carboxyl group is more electronegative in the anti form, so the polarity of the acidic O-H bond is higher in the anti form compared to the syn form, as observed within the limitations of H atom treatment in X-ray diffraction. Consequently, the investigated anti carboxylic acid forms the strongest O-H···O hydrogen bond among all model compounds. Furthermore, according to natural bond orbital analysis, the oxygen lone pairs are clearly nonequivalent, as opposed to the general notion of hybridization of equivalent sp 2 and sp 3 lone pairs on carbonyl or hydroxyl oxygen atoms. The hybridization of the lone pairs is directly related to the directionality and strength of hydrogen bonds.

  12. Dipicolinate salt of imidazole: Discovering its structure and properties using different experimental methodologies and quantum chemical investigations

    Science.gov (United States)

    Thirumurugan, R.; Anitha, K.

    2018-03-01

    A novel organic proton transfer complex of imidazolium dipicolinate (ID) has been synthesized and it was grown as single crystals using slow evaporation method. The molecular structure of synthesized compound and vibrational modes of its functional groups were confirmed by (1H and 13C) NMR, FTIR and FT-Raman spectroscopic studies, respectively. Single crystal X-ray diffraction (SCXRD) analysis confirmed the orthorhombic system with noncentrosymmetric (NCS), P212121, space group of grown ID crystal. UV-Vis-NIR spectral study confirmed its high optical transparency within the region of 285-1500 nm. Powder second harmonic generation (SHG) efficiency of ID crystal was confirmed and it was 6.8 times that of KDP crystal. TG-DTA and DSC analysis revealed the higher thermal stability of grown crystal as 249 °C. The dielectric response and mechanical behaviour of grown crystal were studied effectively. Density functional theory calculations were performed to probe the relationship between the structure and its properties including molecular optimization, Mulliken atomic charge distribution, frontier molecular orbital (FMOs) and molecular electrostatic potential map (MEP) analysis and first hyperpolarizability. All these experimental and computational results were discussed in this communication and it endorsed the ID compound as a potential NLO candidate could be employed in optoelectronics device applications in near future.

  13. Some Phthalocyanine and Naphthalocyanine Derivatives as Corrosion Inhibitors for Aluminium in Acidic Medium: Experimental, Quantum Chemical Calculations, QSAR Studies and Synergistic Effect of Iodide Ions

    Directory of Open Access Journals (Sweden)

    Masego Dibetsoe

    2015-08-01

    Full Text Available The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs namely 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (Pc1, 2,3,9,10,16,17,23,24-octakis(octyloxy-29H,31H-phthalocyanine (Pc2, 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Pc3 and 29H,31H-phthalocyanine (Pc4, and three naphthalocyanines namely 5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine (nPc1, 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (nPc2 and 2,3-naphthalocyanine (nP3 were investigated on the corrosion of aluminium (Al in 1 M HCl using a gravimetric method, potentiodynamic polarization technique, quantum chemical calculations and quantitative structure activity relationship (QSAR. Synergistic effects of KI on the corrosion inhibition properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C. At each concentration of the inhibitor, addition of 0.1% KI increased the inhibition efficiency compared to the absence of KI indicating the occurrence of synergistic interactions between the studied molecules and I− ions. From the potentiodynamic polarization studies, the studied Pcs and nPcs are mixed type corrosion inhibitors both without and with addition of KI. The adsorption of the studied molecules on Al surface obeys the Langmuir adsorption isotherm, while the thermodynamic and kinetic parameters revealed that the adsorption of the studied compounds on Al surface is spontaneous and involves competitive physisorption and chemisorption mechanisms. The experimental results revealed the aggregated interactions between the inhibitor molecules and the results further indicated that the peripheral groups on the compounds affect these interactions. The calculated quantum chemical parameters and the QSAR results revealed the possibility of strong interactions between the studied inhibitors and metal surface. QSAR

  14. Some Phthalocyanine and Naphthalocyanine Derivatives as Corrosion Inhibitors for Aluminium in Acidic Medium: Experimental, Quantum Chemical Calculations, QSAR Studies and Synergistic Effect of Iodide Ions.

    Science.gov (United States)

    Dibetsoe, Masego; Olasunkanmi, Lukman O; Fayemi, Omolola E; Yesudass, Sasikumar; Ramaganthan, Baskar; Bahadur, Indra; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

    2015-08-28

    The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs) namely 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (Pc1), 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (Pc2), 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Pc3) and 29H,31H-phthalocyanine (Pc4), and three naphthalocyanines namely 5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine (nPc1), 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (nPc2) and 2,3-naphthalocyanine (nP3) were investigated on the corrosion of aluminium (Al) in 1 M HCl using a gravimetric method, potentiodynamic polarization technique, quantum chemical calculations and quantitative structure activity relationship (QSAR). Synergistic effects of KI on the corrosion inhibition properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C. At each concentration of the inhibitor, addition of 0.1% KI increased the inhibition efficiency compared to the absence of KI indicating the occurrence of synergistic interactions between the studied molecules and I(-) ions. From the potentiodynamic polarization studies, the studied Pcs and nPcs are mixed type corrosion inhibitors both without and with addition of KI. The adsorption of the studied molecules on Al surface obeys the Langmuir adsorption isotherm, while the thermodynamic and kinetic parameters revealed that the adsorption of the studied compounds on Al surface is spontaneous and involves competitive physisorption and chemisorption mechanisms. The experimental results revealed the aggregated interactions between the inhibitor molecules and the results further indicated that the peripheral groups on the compounds affect these interactions. The calculated quantum chemical parameters and the QSAR results revealed the possibility of strong interactions between the studied inhibitors and metal surface. QSAR analysis on the

  15. Effect of Loop Diameter on the Steady State and Stability Behaviour of Single-Phase and Two-Phase Natural Circulation Loops

    Directory of Open Access Journals (Sweden)

    P. K. Vijayan

    2008-01-01

    Full Text Available In natural circulation loops, the driving force is usually low as it depends on the riser height which is generally of the order of a few meters. The heat transport capability of natural circulation loops (NCLs is directly proportional to the flow rate it can generate. With low driving force, the straightforward way to enhance the flow is to reduce the frictional losses. A simple way to do this is to increase the loop diameter which can be easily adopted in pressure tube designs such as the AHWR and the natural circulation boilers employed in fossil-fuelled power plants. Further, the loop diameter also plays an important role on the stability behavior. An extensive experimental and theoretical investigation of the effect of loop diameter on the steady state and stability behavior of single- and two-phase natural circulation loops have been carried out and the results of this study are presented in this paper.

  16. Optical loop framing

    International Nuclear Information System (INIS)

    Kalibjian, R.; Chong, Y.P.; Prono, D.S.; Cavagnolo, H.R.

    1984-06-01

    The ATA provides an electron beam pulse of 70-ns duration at a 1-Hz rate. Our present optical diagnostics technique involve the imaging of the visible light generated by the beam incident onto the plant of a thin sheet of material. It has already been demonstrated that the light generated has a sufficiently fast temporal reponse in performing beam diagnostics. Notwithstanding possible beam emittance degradation due to scattering in the thin sheet, the observation of beam spatial profiles with relatively high efficiencies has provided data complementary to that obtained from beam wall current monitors and from various x-ray probes and other electrical probes. The optical image sensor consists of a gated, intensified television system. The gate pulse of the image intensifier can be appropriately delayed to give frames that are time-positioned from the head to the tail of the beam with a minimum gate time of 5-ns. The spatial correlation of the time frames from pulse to pulse is very good for a stable electron beam; however, when instabilities do occur, it is difficult to properly assess the spatial composition of the head and the tail of the beam on a pulse-to-pulse basis. Multiple gating within a pulse duration becomes desirable but cannot be performed because the recycle time (20-ms) of the TV system is much longer than the beam pulse. For this reason we have developed an optical-loop framing technique that will allow the recording of two frames within one pulse duration with our present gated/intensified TV system

  17. Possible precursors of ball lightning. Observation of closed loops in high voltage discharges

    Energy Technology Data Exchange (ETDEWEB)

    Alexeff, I.; Rader, M. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-05-01

    Several hundred photographs of ultrahigh voltage discharges have been obtained that show closed current loops. These closed current loops may be precursors of ball lightning. One feature of these discharges may explain why observations of ball lightning may be infrequent; that is, there is a distinct threshold in voltage and/or current below which the closed loops do not occur. This threshold current fits other experimental data but is well above the usually observed currents in natural lightning. 10 refs., 3 figs.

  18. Spectral analysis, structural elucidation and evaluation of chemical reactivity of synthesized ethyl-4-[(2-cyano-acetyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate through experimental studies and quantum chemical calculations

    Science.gov (United States)

    Rawat, P.; Singh, R. N.

    2014-09-01

    This paper describes the synthesis, spectral analysis, structural elucidation and chemical reactivity of pyrrole hydrazide-hydrazone: ethyl-4-[(2-cyano-acetyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (ECAHDPC). The 1H, 13C NMR isotropic chemical shifts and electronic absorption spectra have been calculated by GIAO and TD-DFT methods, respectively, and corroborate well with experimental data. The NH proton of the hydrazide-hydrazones (lbond2 Cdbnd NNHCO) frame appears as singlet at δ = 11.69 ppm due to delocalization of nitrogen lone pair with carbonyl group and its proton involvement in intramolecular H-bonding. The calculated wavenumbers of dimer are in good agreement with the experimental results and confirm that the stable conformer forms dimer by hydrogen bonding interactions between pyrrolic NH and carbonyl Cdbnd O group of ester giving red shift and resonance assisted hydrogen bonding. The binding energy of intermolecular interaction is found to be 10.19 kcal/mol after basis set superposition error correction. QTAIM calculations confirm the existence of intermolecular conventional hydrogen bond (Nsbnd H⋯O), intra and intermolecular non-conventional hydrogen bond (Csbnd H⋯O) and intramolecular interaction (C⋯N). The NBO analysis has been performed to evaluate charge transfer and delocalization of electron density. The static first hyperpolarizability (β0) of monomer has been found to be 6.59 × 10-30 esu. The maximum value of reactivity descriptors (fk+, sk+, ωk+) at C(9) indicate that this site is more susceptible to nucleophilic attack, favoring for the formation of heterocyclic compounds.

  19. Synthesis, an experimental and quantum chemical computational study of a new nonlinear optical material: 2-Picolinium hydrogensquarate

    Science.gov (United States)

    Korkmaz, Ufuk; Bulut, Ahmet

    2014-09-01

    The experimental and theoretical investigation results of a novel organic non-linear optical (NLO) organic squarate salt of 2-Picolinium hydrogensquarate (1), C6H8N·C4HO4-, were reported in this study. The space group of the title compound was found in the monoclinic C2/c space group. It was found that the asymmetric unit consists of one monohydrogen squarate anion together with mono protonated 2-Picolinium, forming the (1) salt. The X-ray analysis clearly indicated that the crystal packing has shown the hydrogen bonding ring pattern of D22(10) (α-dimer) through Nsbnd H⋯O interactions. The hydrogensquarate anions form α-dimer, while 2-Picolinium molecule interacts through Nsbnd H⋯O and Csbnd H⋯O with the hydrogensquarate anion. The structural and vibrational properties of the compound were also studied by computational methods of ab initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 obtained are presented and compared with the X-ray analysis result. On the other the molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained.

  20. Synthesis, an experimental and quantum chemical computational study: Proton sharing in 4-Morpholinium bis(hydrogen squarate)

    Science.gov (United States)

    Korkmaz, Ufuk; Topçu, Yıldıray; Taş, Murat; Bulut, Ahmet

    2015-01-01

    The experimental and theoretical investigation results of a novel organic squarate salt of 4-Morpholinium bis(hydrogen squarate) (1), C6H14ON+ ·C8H3 O8- , were reported in this study. The crystal structure of the title compound was found to crystallize in the triclinic P - 1 space group. In the crystals of 1 the morpholine ring adopts the chair conformation with the ethyl group in the equatorial and hydrogen atoms in axial positions. The hydrogen squarate anions are linked into a homoconjugated anion, [(HSQ)2H], by a short symmetric, nonlinear O8⋯H2⋯O2 hydrogen bond of 2.444 (2) Å. The structural and vibrational properties of the compound were also studied by computational methods of ab-initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The obtained calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 obtained are presented and compared with the X-ray analysis result. On the other hand the molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained.

  1. Combined experimental and computational studies on the physical and chemical properties of the renewable amide, 3-acetamido-5-acetylfuran.

    Science.gov (United States)

    Liu, Yi; Rowley, Christopher N; Kerton, Francesca M

    2014-12-15

    The pK(a) of 3-acetamido-5-acetylfuran (3A5AF) was predicted to be in the range 18.5-21.5 by using the B3LYP/6-311+G(2d,p) method and several amides as references. The experimental pK(a) value, 20.7, was determined through UV/Vis titrations. Its solubility was measured in methanol-modified supercritical CO2 (mole fraction, 3.23×10(-4), cloud points 40-80 °C) and it was shown to be less soluble than 5-hydroxymethylfurfural (5-HMF). Dimerization energies were calculated for 3A5AF and 5-HMF to compare hydrogen bonding, as such interactions will affect their solubility. Infrared and (1) H nuclear magnetic resonance spectra of 3A5AF samples support the existence of intermolecular hydrogen bonding. The highest occupied molecular orbital, lowest unoccupied molecular orbital, and electrostatic potential of 3A5AF were determined through molecular orbital calculations using B3LYP/6-311+G(2d,p). The π-π* transition energy (time-dependent density functional theory study) was compared with UV/Vis data. Calculated atomic charges were used in an attempt to predict the reactivity of 3A5AF. A reaction between 3A5AF and CH3MgBr was conducted. As 3A5AF is a recently developed renewable compound that has previously not been studied extensively, these studies will be helpful in designing future reactions and processes involving this molecule. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Loop quantum cosmology: Recent progress

    Indian Academy of Sciences (India)

    . These techniques and their implications can be illustrated and tested in simple sit- uations by introducing symmetries, which is the origin of loop quantum cosmology. The symmetry reduction can be done in such a way that the characteristic ...

  3. Experimental study of the hydrothermal alteration of a chemical analogue of the French nuclear glass in a thermal gradient: characterization of newly formed phases and of matter transfers

    International Nuclear Information System (INIS)

    Poinssot, Christophe

    1994-01-01

    As the most dangerous radioactive wastes are to be stored in deep geological layers after having been packaged in barrels made of borosilicate glasses, this research report addresses the study of the alteration of such glasses through the study of a chemical analogue. In order to experimentally model phenomena involved within a storage, the studied glass has been submitted to different thermal gradients between 320 and 150 C and during 3 to 5 months. These gradients comply with those met about the parcels, and allows the spatial evolution of the waste parcel at a given moment, as well as the evolution in time (progressive cooling of wastes) to be simultaneously simulated. The different phases formed within the gradient have been studied and characterized by scanning electronic microscopy, semi-quantitative microanalysis, and X-ray micro-diffraction [fr

  4. Dynamical behaviour in coronal loops

    Science.gov (United States)

    Haisch, Bernhard M.

    1986-01-01

    Rapid variability has been found in two active region coronal loops observed by the X-ray Polychromator (XRP) and the Hard X-ray Imaging Spectrometer (HXIS) onboard the Solar Maximum Mission (SMM). There appear to be surprisingly few observations of the short-time scale behavior of hot loops, and the evidence presented herein lends support to the hypothesis that coronal heating may be impulsive and driven by flaring.

  5. Closed Loop Fluid Delivery System

    Science.gov (United States)

    2014-02-28

    loop fluid delivery system (CLFDS) will integrate a vital signs monitor ( VSM ) and high speed infusion pump (Pump) to respond quickly to drops in...Interface (GUI) shows VSM data, allows the user to select from several injury types (head, uncontrolled hemorrhage, controlled hemorrhage, and three total...the bedrock for future Closed Loop Fluid System Pre-Market Approval application(s) to FDA. 6. Major Issues Clinical study testing revealed a

  6. Evaluation of the Antidiabetic Activity and Chemical Composition of Geranium collinum Root Extracts—Computational and Experimental Investigations

    Directory of Open Access Journals (Sweden)

    Sodik Numonov

    2017-06-01

    Full Text Available The root of Geranium collinum Steph is known in Tajik traditional medicine for its hepatoprotective, antioxidant, and anti-inflammatory therapeutic effects. The present study was conducted to evaluate of potential antidiabetic, antioxidant activities, total polyphenolic and flavonoid content from the different extracts (aqueous, aqueous-ethanolic and individual compounds isolated of the root parts of G. collinum. The 50% aqueous-ethanolic extract possesses potent antidiabetic activity, with IC50 values of 0.10 μg/mL and 0.09 μg/mL for the enzymes protein-tyrosine phosphatase (1B PTP-1B and α-glucosidase, respectively. Phytochemical investigations of the 50% aqueous-ethanolic extract of G. collinum, led to the isolation of ten pure compounds identified as 3,3′,4,4′-tetra-O-methylellagic acid (1, 3,3′-di-O-methylellagic acid (2, quercetin (3, caffeic acid (4, (+-catechin (5, (–-epicatechin (6, (–-epigallocatechin (7, gallic acid (8, β-sitosterol-3-O-β-d-glucopyranoside (9, and corilagin (10. Their structures were determined based on 1D and 2D NMR and mass spectrometric analyses. Three isolated compounds exhibited strong inhibitory activity against PTP-1B, with IC50 values below 0.9 μg/mL, more effective than the positive control (1.46 μg/mL. Molecular docking analysis suggests polyphenolic compounds such as corilagin, catechin and caffeic acid inhibit PTP-1B and β-sitosterol-3-O-β-d-gluco-pyranoside inhibits α-glucosidase. The experimental results suggest that the biological activity of G. collinum is related to its polyphenol contents. The results are also in agreement with computational investigations. Furthermore, the potent antidiabetic activity of the 50% aqueous-ethanolic extract from G. collinum shows promise for its future application in medicine. To the best of our knowledge, we hereby report, for the first time, the antidiabetic activity of G. collinum.

  7. Atomistic simulations of the formation of -component dislocation loops in α-zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Cong, E-mail: dai.cong@queensu.ca; Balogh, Levente; Yao, Zhongwen; Daymond, Mark R., E-mail: mark.daymond@queensu.ca

    2016-09-15

    The formation of -component dislocation loops in α-Zr is believed to be responsible for the breakaway irradiation growth experimentally observed under high irradiation fluences. However, while -loop growth is well described by existing models, the atomic mechanisms responsible for the nucleation of -component dislocation loops are still not clear. In the present work, both interstitial and vacancy -type dislocation loops are initially equilibrated at different temperatures. Cascades simulations in the vicinity of the -type loops are then performed by selecting an atom as the primary knock-on atoms (PKAs) with different kinetic energies, using molecular dynamics simulations. No -component dislocation loop was formed in cascades simulations with a 10 keV PKA, but -component interstitial loops were observed after the interaction between discontinuous 50 keV PKAs and pre-existing -type interstitial loops. The comparisons of cascades simulations in volumes having pre-existing -type interstitial and vacancy loops suggest that the reaction between the PKAs and -type interstitial loops is responsible for the formation of -component interstitial loops.

  8. Combined experimental and quantum chemical studies on spectroscopic (FT-IR, FT-Raman, UV-Vis, and NMR) and structural characteristics of quinoline-5-carboxaldehyde

    Science.gov (United States)

    Kumru, Mustafa; Altun, Ahmet; Kocademir, Mustafa; Küçük, Vesile; Bardakçı, Tayyibe; Şaşmaz, İbrahim

    2016-12-01

    Comparative experimental and theoretical studies have been performed on the structure and spectral (FT-IR, FT-Raman, UV-Vis and NMR) features of quinoline-5-carboxaldehyde. Quantum chemical calculations have been carried out at Hartree-Fock and density functional B3LYP levels with the triple-zeta 6-311++G** basis set. Two stable conformers of quinoline-5-carboxaldehyde arising from the orientation of the carboxaldehyde moiety have been located at the room temperature. The energetic separation of these conformers is as small as 2.5 kcal/mol with a low transition barrier (around 9 kcal/mol). Therefore, these conformers are expected to coexist at the room temperature. Several molecular characteristics of quinoline-5-carboxaldehyde obtained through B3LYP and time-dependent B3LYP calculations, such as conformational stability, key geometry parameters, vibrational frequencies, IR and Raman intensities, UV-Vis vertical excitation energies and the corresponding oscillator strengths have been analyzed. The 1H and 13C NMR chemical shifts of quinoline-5-carboxaldehyde were also investigated.

  9. Determination of structural, spectrometric and nonlinear optical features of 2-(4-hydroxyphenylazo)benzoic acid by experimental techniques and quantum chemical calculations

    Science.gov (United States)

    Cinar, Mehmet; Yildiz, Nihat; Karabacak, Mehmet; Kurt, Mustafa

    2013-03-01

    The optimized geometrical structure, vibrational and electronic transitions, chemical shifts and nonlinear optical properties of 2-(4-hydroxyphenylazo)benzoic acid (HABA) compound were presented in this study. The ground state geometrical structure and vibrational wavenumbers were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman spectrometry in the range of 4000-400 cm-1 and 4000-10 cm-1; respectively. The fundamental assignments were done on the basis of the recorded spectra and total energy distribution (TED) of the vibrational modes. The 1H and 13C NMR spectra were recorded in deuterated DMSO solution, and gauge-invariant atomic orbitals (GIAOs) method was used to predict the isotropic chemical shifts. The UV-Vis absorption spectra of the compound were observed in the range of 200-800 nm in ethanol, methanol and water solvents. To investigate the nonlinear optical properties, the polarizability, anisotropy of polarizability and molecular first hyperpolarizability were computed. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations.

  10. Technical note: Monte Carlo genetic algorithm (MCGA) for model analysis of multiphase chemical kinetics to determine transport and reaction rate coefficients using multiple experimental data sets

    Science.gov (United States)

    Berkemeier, Thomas; Ammann, Markus; Krieger, Ulrich K.; Peter, Thomas; Spichtinger, Peter; Pöschl, Ulrich; Shiraiwa, Manabu; Huisman, Andrew J.

    2017-06-01

    We present a Monte Carlo genetic algorithm (MCGA) for efficient, automated, and unbiased global optimization of model input parameters by simultaneous fitting to multiple experimental data sets. The algorithm was developed to address the inverse modelling problems associated with fitting large sets of model input parameters encountered in state-of-the-art kinetic models for heterogeneous and multiphase atmospheric chemistry. The MCGA approach utilizes a sequence of optimization methods to find and characterize the solution of an optimization problem. It addresses an issue inherent to complex models whose extensive input parameter sets may not be uniquely determined from limited input data. Such ambiguity in the derived parameter values can be reliably detected using this new set of tools, allowing users to design experiments that should be particularly useful for constraining model parameters. We show that the MCGA has been used successfully to constrain parameters such as chemical reaction rate coefficients, diffusion coefficients, and Henry's law solubility coefficients in kinetic models of gas uptake and chemical transformation of aerosol particles as well as multiphase chemistry at the atmosphere-biosphere interface. While this study focuses on the processes outlined above, the MCGA approach should be portable to any numerical process model with similar computational expense and extent of the fitting parameter space.

  11. An experimental and quantum chemical study of removal of utmostly quantified heavy metals in wastewater using coconut husk: A novel approach to mechanism.

    Science.gov (United States)

    Malik, Reena; Dahiya, Shefali; Lata, Suman

    2017-05-01

    The present study explores the uptake capacity of low cost agricultural waste i.e.Unmodified Coconut (Cocos nucifera L.) Husk for the removal of heavy metal (Pb 2+ , Cu 2+ , Ni 2+ and Zn 2+ ) ions from industrial wastewater. The effect of various operational parameters such as adsorbent dose, high initial metal concentration (100mg/L-500mg/L), pH, temperature and agitation time on the removal of these ions has been investigated using batch experiments. The results showed that maximum uptake through adsorption occurred at 443.0mg/g (88.6%) for Cu, for Ni with 404.5mg/g (80.9%), 362.2mg/g (72.4%) for Pb 2+ and 338.0mg/g (67.6%) for Zn 2+ ion simultaneously. The adsorption capacity was found to be sensitive to the amount of adsorbent, heavy metal ion concentration, pH, temperature and contact time. The experimental statistics have been correlated and interpreted by a new proposed mechanism based upon quantum chemical study of the adsorbent. The theoretical study using quantum has provided the rich electron donation sites of Coconut Husk and hence proposed mechanism of removal. The various adsorption isotherms (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Flory-Huggins), SEM study and physico-chemical properties of the ions suit well to the observed data. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Technical note: Monte Carlo genetic algorithm (MCGA for model analysis of multiphase chemical kinetics to determine transport and reaction rate coefficients using multiple experimental data sets

    Directory of Open Access Journals (Sweden)

    T. Berkemeier

    2017-06-01

    Full Text Available We present a Monte Carlo genetic algorithm (MCGA for efficient, automated, and unbiased global optimization of model input parameters by simultaneous fitting to multiple experimental data sets. The algorithm was developed to address the inverse modelling problems associated with fitting large sets of model input parameters encountered in state-of-the-art kinetic models for heterogeneous and multiphase atmospheric chemistry. The MCGA approach utilizes a sequence of optimization methods to find and characterize the solution of an optimization problem. It addresses an issue inherent to complex models whose extensive input parameter sets may not be uniquely determined from limited input data. Such ambiguity in the derived parameter values can be reliably detected using this new set of tools, allowing users to design experiments that should be particularly useful for constraining model parameters. We show that the MCGA has been used successfully to constrain parameters such as chemical reaction rate coefficients, diffusion coefficients, and Henry's law solubility coefficients in kinetic models of gas uptake and chemical transformation of aerosol particles as well as multiphase chemistry at the atmosphere–biosphere interface. While this study focuses on the processes outlined above, the MCGA approach should be portable to any numerical process model with similar computational expense and extent of the fitting parameter space.

  13. Natural Circulation Characteristics of a Symmetric Loop under Inclined Conditions

    Directory of Open Access Journals (Sweden)

    Xingtuan Yang

    2014-01-01

    Full Text Available Natural circulation is an important process for primary loops of some marine integrated reactors. The reactor works under inclined conditions when severe accidents happen to the ship. In this paper, to investigate the characteristics of natural circulation, experiments were conducted in a symmetric loop under the inclined angle of 0~45°. A CFD model was also set up to predict the behaviors of the loop beyond the experimental scope. Total circulation flow rate decreases with the increase of inclined angle. Meanwhile one circulation is depressed while the other is enhanced, and accordingly the disparity between the branch circulations arises and increases with the increase of inclined angle. Circulation only takes place in one branch circuit at large inclined angle. Also based on the CFD model, the influences of flow resistance distribution and loop configuration on natural circulation are predicted. The numerical results show that to design the loop with the configuration of big altitude difference and small width, it is favorable to reduce the influence of inclination; however too small loop width will cause severe reduction of circulation ability at large angle inclination.

  14. Assessing catchment connectivity using hysteretic loops

    Science.gov (United States)

    Davis, Jason; Masselink, Rens; Goni, Mikel; Gimenez, Rafael; Casali, Javier; Seeger, Manuel; Keesstra, Saskia

    2017-04-01

    Storm events mobilize large proportions of sediments in catchment systems. Therefore understanding catchment sediment dynamics throughout the continuity of storms and how initial catchment states act as controls on the transport of sediment to catchment outlets is important for effective catchment management. Sediment connectivity is a concept which can explain the origin, pathways and sinks of sediments within catchments (Baartman et al., 2013; Parsons et al., 2015; Masselink et al., 2016a,b; Mekonnen et al., 2016). However, sediment connectivity alone does not provide a practicable mechanism by which the catchment's initial state - and thus the location of entrained sediment in the sediment transport cascade - can be characterized. Studying the dynamic relationship between water discharge (Q) and suspended sediment (SS) at the catchment outlet can provide a valuable research tool to infer the likely source areas and flow pathways contributing to sediment transport because the relationship can be characterized by predictable hysteresis patterns. Hysteresis is observed when the sediment concentration associated with a certain flow rate is different depending on the direction in which the analysis is performed - towards the increase or towards the diminution of the flow. However, the complexity of the phenomena and factors which determine the hysteresis make its interpretation ambiguous. Previous work has described various types of hysteretic loops as well as the cause for the shape of the loop, mainly pointing to the origin of the sediments. The data set for this study comes from four experimental watersheds in Navarre (Spain), owned and maintained by the Government of Navarre. These experimental watersheds have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz principal and Oskotz woodland). La Tejería and Latxaga watersheds are similar to each other regarding size (approximately 200 ha), geology (marls and sandstones), soils (fine

  15. Thermochemistry of ionic liquid-catalyzed reactions. experimental and theoretical study of chemical equilibria of isomerization and transalkylation of tert-butylbenzenes.

    Science.gov (United States)

    Verevkin, Sergey P; Kozlova, Svetlana A; Emel'yanenko, Vladimir N; Goodrich, Peter; Hardacre, Christopher

    2008-11-06

    The chemical equilibrium of mutual interconversions of tert-butylbenzenes was studied in the temperature range 286 to 423 K using chloroaluminate ionic liquids as a catalyst. Enthalpies of five reactions of isomerization and transalkylation of tert-butylbenzenes were obtained from temperature dependences of the corresponding equilibrium constants in the liquid phase. Molar enthalpies of vaporization of methyl-tert-butylbenzenes and 1,4-di tert-butylbenzene were obtained by the transpiration method and were used for a recalculation of enthalpies of reactions and equilibrium constants into the gaseous phase. Using these experimental results, ab initio methods (B3LYP and G3MP2) have been tested for prediction thermodynamic functions of the five reactions under study successfully. Thermochemical investigations of tert-butylbenzenes available in the literature combined with experimental results have helped to resolve contradictions in the available thermochemical data for tert-butylbenzene and to recommend consistent and reliable enthalpies of formation for this compound in the liquid and the gaseous state.

  16. Surface sensing behavior and band edge properties of AgAlS2: Experimental observations in optical, chemical, and thermoreflectance spectroscopy

    Directory of Open Access Journals (Sweden)

    Ching-Hwa Ho

    2012-06-01

    Full Text Available Optical examination of a chaocogenide compound AgAlS2 which can spontaneously transfer to a AgAlO2 oxide has been investigated by thermoreflectance (TR spectroscopy herein. The single crystals of AgAlS2 were grown by chemical vapor transport (CVT method using ICl3 as a transport agent sealed in evacuated quartz tubes. The as-grown AgAlS2 crystals essentially possess a transparent and white color in vacuum. The crystal surface of AgAlS2 becomes darkened and brownish when putting AgAlS2 into atmosphere for reacting with water vapor or hydrogen gas. Undergoing the chemical reaction process, oxygen deficient AgAlO2-2x with brownish and reddish-like color on surface of AgAlS2 forms. The transition energy of deficient AgAlO2-2x was evaluated by TR experiment. The value was determined to be ∼2.452 eV at 300 K. If the sample is kept dry and moved away from moisture, AgAlS2 crystal can stop forming more deficient AgAlO2-2x surface oxides. The experimental TR spectra for the surface-reacted sample show clearly two transition features at EW=2.452 eV for deficient AgAlO2-2x and EU=3.186 eV for AgAlS2, respectively. The EU transition belongs to direct band-edge exciton of AgAlS2. Alternatively, for surface-oxidation process of AgAlS2 lasting for a long time, a AgAlO2 crystal with yellowish color will eventually form. The TR measurements show mainly a ground-state band edge exciton of E OX 1 detected for AgAlO2. The energy was determined to be E OX 1=2.792 eV at 300 K. The valence-band electronic structure of AgAlS2 has been detailed characterized using polarized-thermoreflectance (PTR measurements in the temperature range between 30 and 340 K. Physical chemistry behaviors of AgAlS2 and AgAlO2 have been comprehensively studied via detailed analyses of PTR and TR spectra. Based on the experimental analyses, optical and chemical behaviors of the AgAlS2 crystals under atmosphere are realized. A possible optical-detecting scheme for using AgAlS2 as a humidity

  17. Tensile capacity of loop connections grouted with concrete or mortar

    DEFF Research Database (Denmark)

    Sørensen, Jesper Harrild; Hoang, Linh Cao; Olesen, John Forbes

    2017-01-01

    This paper presents a study of grout failure in symmetric U-bar loop connections loaded in tension, with focus on the performance of two grouting materials – concrete and mortar. The study contains an experimental investigation as well as a rigid-plastic modelling of the tensile capacity. The tes...

  18. Scoping erosion flow loop test results in support of Hanford WTP

    International Nuclear Information System (INIS)

    Duignan, M.; Imrich, K.; Fowley, M.; Restivo, M.; Reigel, M.

    2015-01-01

    The Waste Treatment and Immobilization Plant (WTP) will process Hanford Site tank waste by converting the waste into a stable glass form. Before the tank waste can be vitrified, the baseline plan is to process the waste through the Pretreatment (PT) Facility where it will be mixed in various process vessels using Pulse Jet Mixers (PJM) and transferred to the High Level Waste (HLW) or Low Activity Waste (LAW) vitrification facilities. The Department of Energy (DOE) and Defense Nuclear Facility Safety Board (DNFSB), as well as independent review groups, have raised concerns regarding the design basis for piping erosion in the PT Facility. Due to the complex nature of slurry erosion/corrosion wear and the unique conditions that exist within the PT Facility, additional testing has been recommended by these entities. Pipe loop testing is necessary to analyze the potential for localized wear at elbows and bends, close the outstanding PT and HLW erosion/corrosion technical issues, and underpin BNI's design basis for a 40-year operational life for black cell piping and vessels. SRNL is consulting with the DOE Office of River Protection (ORP) to resolve technical concerns related to piping erosion/corrosion (wear) design basis for PT. SRNL was tasked by ORP to start designing, building, and testing a flow loop to obtain long-term total-wear rate data using bounding simulant chemistry, operating conditions, and prototypical materials. The initial test involved a scoping paint loop to locate experimentally the potential high-wear locations. This information will provide a basis for the placement of the many sensitive wear measurement instruments in the appropriate locations so that the principal flow-loop test has the best chance to estimate long-term erosion and corrosion. It is important to note that the scoping paint loop test only utilized a bounding erosion simulant for this test. A full chemical simulant needs to be added for the complete test flow loop. The

  19. Temperature measurement of accelerator cell solenoid loop

    International Nuclear Information System (INIS)

    Mu Fan; Dong Pan; Dai Zhiyong

    2010-01-01

    This paper presents the research on temperature measurement of solenoid loop. The measuring temperature fiber is layered in solenoid loop for the accelerator cell. When the solenoid loop is supplied with high current form a constant current source, its temperature increases rapidly. The temperature fiber can measure the temperature of the solenoid loop and get temperature measurement rule. Experiment and simulation show temperature of interior solenoid loop the highest and it decreases from the interior to the exterior of solenoid loop. To control temperature of solenoid loop under 60 degree C, simulation displays load interval of constant current source with 80 A current should be at least is 17.5 minutes. (authors)

  20. A LabVIEW model incorporating an open-loop arterial impedance and a closed-loop circulatory system.

    Science.gov (United States)

    Cole, R T; Lucas, C L; Cascio, W E; Johnson, T A

    2005-11-01

    While numerous computer models exist for the circulatory system, many are limited in scope, contain unwanted features or incorporate complex components specific to unique experimental situations. Our purpose was to develop a basic, yet multifaceted, computer model of the left heart and systemic circulation in LabVIEW having universal appeal without sacrificing crucial physiologic features. The program we developed employs Windkessel-type impedance models in several open-loop configurations and a closed-loop model coupling a lumped impedance and ventricular pressure source. The open-loop impedance models demonstrate afterload effects on arbitrary aortic pressure/flow inputs. The closed-loop model catalogs the major circulatory waveforms with changes in afterload, preload, and left heart properties. Our model provides an avenue for expanding the use of the ventricular equations through closed-loop coupling that includes a basic coronary circuit. Tested values used for the afterload components and the effects of afterload parameter changes on various waveforms are consistent with published data. We conclude that this model offers the ability to alter several circulatory factors and digitally catalog the most salient features of the pressure/flow waveforms employing a user-friendly platform. These features make the model a useful instructional tool for students as well as a simple experimental tool for cardiovascular research.

  1. Principles of agonist recognition in Cys-loop receptors

    Directory of Open Access Journals (Sweden)

    Timothy eLynagh

    2014-04-01

    Full Text Available Cys-loop receptors are ligand-gated ion channels that are activated by a structurally diverse array of neurotransmitters, including acetylcholine, serotonin, glycine and GABA. After the term chemoreceptor emerged over 100 years ago, there was some wait until affinity labeling, molecular cloning, functional studies and X-ray crystallography experiments identified the extracellular interface of adjacent subunits as the principal site of agonist binding. The question of how subtle differences at and around agonist-binding sites of different Cys-loop receptors can accommodate transmitters as chemically diverse as glycine and serotonin has been subject to intense research over the last three decades. This review outlines the functional diversity and current structural understanding of agonist-binding sites, including those of invertebrate Cys-loop receptors. Together, this provides a framework to understand the atomic determinants involved in how these valuable therapeutic targets recognize and bind their ligands.

  2. Virtual Induction Loops Based on Cooperative Vehicular Communications

    Science.gov (United States)

    Gramaglia, Marco; Bernardos, Carlos J.; Calderon, Maria

    2013-01-01

    Induction loop detectors have become the most utilized sensors in traffic management systems. The gathered traffic data is used to improve traffic efficiency (i.e., warning users about congested areas or planning new infrastructures). Despite their usefulness, their deployment and maintenance costs are expensive. Vehicular networks are an emerging technology that can support novel strategies for ubiquitous and more cost-effective traffic data gathering. In this article, we propose and evaluate VIL (Virtual Induction Loop), a simple and lightweight traffic monitoring system based on cooperative vehicular communications. The proposed solution has been experimentally evaluated through simulation using real vehicular traces. PMID:23348033

  3. Virtual Induction Loops Based on Cooperative Vehicular Communications

    Directory of Open Access Journals (Sweden)

    Maria Calderon

    2013-01-01

    Full Text Available Induction loop detectors have become the most utilized sensors in traffic management systems. The gathered traffic data is used to improve traffic efficiency (i.e., warning users about congested areas or planning new infrastructures. Despite their usefulness, their deployment and maintenance costs are expensive. Vehicular networks are an emerging technology that can support novel strategies for ubiquitous and more cost-effective traffic data gathering. In this article, we propose and evaluate VIL (Virtual Induction Loop, a simple and lightweight traffic monitoring system based on cooperative vehicular communications. The proposed solution has been experimentally evaluated through simulation using real vehicular traces.

  4. Acceleration of Feynman loop integrals in high-energy physics on many core GPUs

    International Nuclear Information System (INIS)

    Yuasa, F; Ishikawa, T; Hamaguchi, N; Koike, T; Nakasato, N

    2013-01-01

    The current and future colliders in high-energy physics require theorists to carry out a large scale computation for a precise comparison between experimental results and theoretical ones. In a perturbative approach several methods to evaluate Feynman loop integrals which appear in the theoretical calculation of cross-sections are well established in the one-loop level, however, more studies are necessary for higher-order levels. Direct Computation Method (DCM) is developed to evaluate multi-loop integrals. DCM is based on a combination of multidimensional numerical integration and extrapolation on a sequence of integrals. It is a fully numerical method and is applicable to a wide class of integrals with various physics parameters. The computation time depends on physics parameters and the topology of loop diagrams and it becomes longer for the two-loop integrals. In this paper we present our approach to the acceleration of the two-loop integrals by DCM on multiple GPU boards

  5. Thermodynamics in Loop Quantum Cosmology

    International Nuclear Information System (INIS)

    Li, L.F.; Zhu, J.Y.

    2009-01-01

    Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. Moreover, the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but also are actually found to be the thermodynamic quantities. This result comes from the energy definition in cosmology (the Misner-Sharp gravitational energy) and is consistent with thermodynamic laws. We prove that within the framework of loop quantum cosmology, the elementary equation of equilibrium thermodynamics is still valid.

  6. Aggressive chemical decontamination tests on small valves from the Garigliano BWR

    International Nuclear Information System (INIS)

    Bregani, F.

    1990-01-01

    In order to check the effectiveness of direct chemical decontamination on small and complex components, usually considered for storage without decontamination because of the small amount, some tests were performed on the DECO experimental loop. Four small stainless steel valves from the primary system of the Garigliano BWR were decontaminated using mainly aggressive chemicals such as HC1, HF, HNO 3 and their mixtures. On two valves, before the treatment with aggressive chemicals, a step with soft chemical (oxalic and citric acid mixture) was performed in order to see whether a softening action enhances the following aggressive decontamination. Moreover, in order to increase as much as possible the decontamination effectiveness, a decontamination process using ultrasounds jointly with aggressive chemicals was investigated. After an intensive laboratory testing programme, two smaller stainless steel valves from the primary system of the Garigliano BWR were decontaminated using ultrasounds in aggressive chemical solutions

  7. Virtual velocity loop based on MEMS accelerometers for optical stabilization control system

    Science.gov (United States)

    Ren, Wei; Deng, Chao; Mao, Yao; Ren, Ge

    2017-08-01

    In the optical stabilization control system (OSCS) control system based on a charge-coupled device (CCD), stabilization performance of the line-of-sight is severely limited by the mechanical resonance and the low sampling rate of the CCD. An approach to improve the stabilization performance of the OSCS control system with load restriction based on three loops, including an acceleration loop, a virtual velocity loop, and a position loop, by using MEMS accelerometers and a CCD is proposed. The velocity signal is obtained by accelerators instead of gyro sensors. Its advantages are low power, low cost, small size, and wide measuring range. A detailed analysis is provided to show how to design the virtual velocity loop and correct virtual velocity loop drift. Experimental results show that the proposed multiloop feedback control method with virtual velocity loop in which the disturbance suppression performance is better than that of the dual loop control with only an acceleration loop and a position loop at low frequency.

  8. LISA Pathfinder: OPD loop characterisation

    Science.gov (United States)

    Born, Michael; LPF Collaboration

    2017-05-01

    The optical metrology system (OMS) of the LISA Pathfinder mission is measuring the distance between two free-floating test masses with unprecedented precision. One of the four OMS heterodyne interferometers reads out the phase difference between the reference and the measurement laser beam. This phase from the reference interferometer is common to all other longitudinal interferometer read outs and therefore subtracted. In addition, the phase is fed back via the digital optical pathlength difference (OPD) control loop to keep it close to zero. Here, we analyse the loop parameters and compare them to on-ground measurement results.

  9. Fermions and loops on graphs: I. Loop calculus for determinants

    International Nuclear Information System (INIS)

    Chernyak, Vladimir Y; Chertkov, Michael

    2008-01-01

    This paper is the first in a series devoted to evaluation of the partition function in statistical models on graphs with loops in terms of the Berezin/fermion integrals. The paper focuses on a representation of the determinant of a square matrix in terms of a finite series, where each term corresponds to a loop on the graph. The representation is based on a fermion version of the loop calculus, previously introduced by the authors for graphical models with finite alphabets. Our construction contains two levels. First, we represent the determinant in terms of an integral over anti-commuting Grassmann variables, with some reparametrization/gauge freedom hidden in the formulation. Second, we show that a special choice of the gauge, called the BP (Bethe–Peierls or belief propagation) gauge, yields the desired loop representation. The set of gauge fixing BP conditions is equivalent to the Gaussian BP equations, discussed in the past as efficient (linear scaling) heuristics for estimating the covariance of a sparse positive matrix

  10. Amino-acid composition after loop deletion drives domain swapping.

    Science.gov (United States)

    Nandwani, Neha; Surana, Parag; Udgaonkar, Jayant B; Das, Ranabir; Gosavi, Shachi

    2017-10-01

    Rational engineering of a protein to enable domain swapping requires an understanding of the sequence, structural and energetic factors that favor the domain-swapped oligomer over the monomer. While it is known that the deletion of loops between β-strands can promote domain swapping, the spliced sequence at the position of the loop deletion is thought to have a minimal role to play in such domain swapping. Here, two loop-deletion mutants of the non-domain-swapping protein monellin, frame-shifted by a single residue, were designed. Although the spliced sequence in the two mutants differed by only one residue at the site of the deletion, only one of them (YEIKG) promoted domain swapping. The mutant containing the spliced sequence YENKG was entirely monomeric. This new understanding that the domain swapping propensity after loop deletion may depend critically on the chemical composition of the shortened loop will facilitate the rational design of domain swapping. © 2017 The Protein Society.

  11. Experimental examination of the Mg-silicate-carbonate system at ambient temperature: Implications for alkaline chemical sedimentation and lacustrine carbonate formation

    Science.gov (United States)

    Tutolo, Benjamin M.; Tosca, Nicholas J.

    2018-03-01

    Despite their clear economic significance, Cretaceous presalt carbonates of the South Atlantic continental margins are not well-described by published facies models. This knowledge gap arises, in part, because the chemical processes that generate distinctive sedimentary products in alkaline, non-marine environments are poorly understood. Here, we use constraints inferred from reported mineralogical and geochemical features of presalt carbonate rocks to design and perform a suite of laboratory experiments to quantify the processes of alkaline chemical sedimentation. Using real-time observations of in-situ fluid chemistry, post-experiment analysis of precipitated solids, and geochemical modeling tools, we illustrate that spherulitic carbonates and Mg-silicate clays observed in presalt carbonates were likely precipitated from elevated pH (∼10-10.5) waters with high concentrations of silica and alkali cations typical of intermediate to felsic rocks, such as Na+ and K+. Charge balance constraints require that these cations were not counterbalanced to any significant degree by anions typical of seawater, such as Cl- and SO4-, which implies minimal seawater involvement in presalt deposition. Experimental data suggest that, at this alkaline pH, only modest concentrations (i.e., ∼0.5-1 mmol/kg) of Ca++ would have been required to precipitate spheroidal CaCO3. Given the rapid rates of CaCO3 nucleation and growth under such conditions, it is unlikely that Ca++ concentrations in lake waters ever exceeded these values, and sustained chemical fluxes are therefore required for extensive sediment accumulation. Moreover, our experiments indicate that the original mineralogy of presalt CaCO3 could have been calcite or aragonite, but the differing time scales of precipitation between CaCO3 and Mg-silicates would have tended to skew the Mg/Ca ratio in solution towards elevated values which favor aragonite. Mg-silicate nucleation and growth rates measured during our experiments

  12. Combined coagulation-flocculation and sequencing batch reactor with phosphorus adjustment for the treatment of high-strength landfill leachate: experimental kinetics and chemical oxygen demand fractionation.

    Science.gov (United States)

    El-Fadel, M; Matar, F; Hashisho, J

    2013-05-01

    The treatability of high-strength landfill leachate is challenging and relatively limited. This study examines the feasibility of treating high-strength landfill leachate (chemical oxygen demand [COD]: 7,760-11,770 mg/L, biochemical oxygen demand [BOD5]: 2,760-3,569 mg/L, total nitrogen [TN] = 980-1,160 mg/L) using a sequencing batch reactor (SBR) preceded by a coagulation-flocculation process with phosphorus nutritional balance under various mixing and aeration patterns. Simulations were also conducted to define kinetic parameters and COD fractionation. Removal efficiencies reached 89% for BOD5, 60% for COD, and 72% for TN, similar to and better than reported studies, albeit with a relatively lower hydraulic retention time (HRT) and solid retention time (SRT). The coupled experimental and simulation results contribute in filling a gap toward managing high-strength landfill leachate and providing guidelines for corresponding SBR applications. The treatability of high-strength landfill leachate, which is challenging and relatively limited, was demonstrated using a combined coagulation-flocculation with SBR technology and nutrient balance adjustment. The most suitable coagulant, kinetic design parameters, and COD fractionation were defined using coupled experimental and simulation results contributing in filling a gap toward managing high-strength leachate by providing guidelines for corresponding SBR applications and anticipating potential constraints related to the non-biodegradable COD fraction. In this context, while the combined coagulation-flocculation and SBR process improved removal efficiencies, posttreatment may be required for high-strength leachate, depending on discharge standards and ultimate usage of the treated leachate.

  13. ABJM Wilson loops in arbitrary representations

    International Nuclear Information System (INIS)

    Hatsuda, Yasuyuki; Moriyama, Sanefumi; Okuyama, Kazumi

    2013-06-01

    We study vacuum expectation values (VEVs) of circular half BPS Wilson loops in arbitrary representations in ABJM theory. We find that those in hook representations are reduced to elementary integrations thanks to the Fermi gas formalism, which are accessible from the numerical studies similar to the partition function in the previous studies. For non-hook representations, we show that the VEVs in the grand canonical formalism can be exactly expressed as determinants of those in the hook representations. Using these facts, we can study the instanton effects of the VEVs in various representations. Our results are consistent with the worldsheet instanton effects studied from the topological string and a prescription to include the membrane instanton effects by shifting the chemical potential, which has been successful for the partition function.

  14. ABJM Wilson loops in arbitrary representations

    Energy Technology Data Exchange (ETDEWEB)

    Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Honda, Masazumi [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst. and Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics

    2013-06-15

    We study vacuum expectation values (VEVs) of circular half BPS Wilson loops in arbitrary representations in ABJM theory. We find that those in hook representations are reduced to elementary integrations thanks to the Fermi gas formalism, which are accessible from the numerical studies similar to the partition function in the previous studies. For non-hook representations, we show that the VEVs in the grand canonical formalism can be exactly expressed as determinants of those in the hook representations. Using these facts, we can study the instanton effects of the VEVs in various representations. Our results are consistent with the worldsheet instanton effects studied from the topological string and a prescription to include the membrane instanton effects by shifting the chemical potential, which has been successful for the partition function.

  15. The double-loop feedback for active learning with understanding

    DEFF Research Database (Denmark)

    Christensen, Hans Peter

    2004-01-01

    Learning is an active process, and in engineering education authentic projects is often used to activate the students and promote learning. However, it is not all activity that leads to deep learning; and in a rapid changing society deep understanding is necessary for life-long learning. Empirical...... findings at DTU question the direct link between high activity and a deep approach to learning. Active learning is important to obtain engineering competencies, but active learning requires more than activity. Feedback and reflection is crucial to the learning process, since new knowledge is built...... on the student’s existing understanding. A model for an active learning process with a double-loop feedback is suggested - the first loop gives the student experience through experimentation, the second conceptual understanding through reflection. Students often miss the second loop, so it is important...

  16. Quantum chemical investigation of thermal cis-to-trans isomerization of azobenzene derivatives: substituent effects, solvent effects, and comparison to experimental data.

    Science.gov (United States)

    Dokić, Jadranka; Gothe, Marcel; Wirth, Jonas; Peters, Maike V; Schwarz, Jutta; Hecht, Stefan; Saalfrank, Peter

    2009-06-18

    Quantum chemical calculations of various azobenzene (AB) derivatives have been carried out with the goal to describe the energetics and kinetics of their thermal cis --> trans isomerization. The effects of substituents, in particular their type, number, and positioning, on activation energies have been systematically studied with the ultimate goal to tailor the switching process. Trends observed for mono- and disubstituted species are discussed. A polarizable continuum model is used to study, in an approximate fashion, the cis --> trans isomerization of azobenzenes in solution. The nature of the transition state(s) and its dependence on substituents and the environment is discussed. In particular for push-pull azobenzenes, the reaction mechanism is found to change from inversion in nonpolar solvents to rotation in polar solvents. Concerning kinetics, calculations based on the Eyring transition state theory give usually reliable activation energies and enthalpies when compared to experimentally determined values. Also, trends in the resulting rate constants are correct. Other computed properties such as activation entropies and thus preexponential rate factors are in only moderate agreement with experiment.

  17. Experimental study of chemical-mechanical coupling during percolation of reactive fluid through rocks under stress, in the context of the CO2 geological sequestration

    International Nuclear Information System (INIS)

    Le Guen, Y.

    2006-10-01

    CO 2 injection into geological repositories will induce chemical and mechanical instabilities. The study of these instabilities is based on experimental deformation of natural rock samples under stress, in the presence of fluids containing, or not, dissolved CO 2 . Triaxial cells used for the experiments permitted an independent control and measurement of stress, temperature, fluid pressure and composition. Vertical strains were measured during several months, with a resolution of 1.10 -12 s -1 on the strain rate. Simultaneously, fluids were analysed in order to quantify fluid-rock interactions. For limestone samples, percolation of CO 2 -rich fluids increases strain rate by a factor 1.7 up to 5; on the other hand, sandstone deformation remained almost the same. Increase in strain rate with limestone samples was explained by injected water acidification by the CO 2 which increases rock solubility and reaction kinetics. On the opposite, small effect of CO 2 on quartz explains the absence of deformation. X-ray observations confirmed the importance of rock composition and structure on the porosity evolution. Numerical simulations of rock elastic properties showed increasing shear stress into the sample. Measured deformation showed an evolution of reservoir rocks mechanical properties. It was interpreted as the consequence of pressure solution mechanisms both at grains contacts and on grain free surfaces. (author)

  18. Feedback - closing the loop digitally

    International Nuclear Information System (INIS)

    Zagel, J.; Chase, B.

    1992-01-01

    Many feedback and feedforward systems are now using microprocessors within the loop. We describe the wide range of possibilities and problems that arise. We also propose some ideas for analysis and testing, including examples of motion control in the Flying Wire systems in Main Ring and Tevatron and Low Level RF control now being built for the Fermilab Linac upgrade. (author)

  19. Closing the Loop with Exercises

    Science.gov (United States)

    Altizer, Andy

    2008-01-01

    Conducting exercises provides a critical bridge between the theory of an Emergency Action Plan and its effective implementation. When conducted properly, exercises can fill the gap between training and after-action review to close the preparedness loop--before an actual emergency occurs. Often exercises are planned and conducted on campus based on…

  20. Two loops in eleven dimensions

    CERN Document Server

    Green, Michael B.; Vanhove, Pierre; Green, Michael B.; Kwon, Hwang-h.; Vanhove, Pierre

    2000-01-01

    The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus, T^2, is analyzed in detail. The Schwinger parameter integrations are re-expressed as integration over the moduli space of a second torus, \\hat T^2, which enables the leading low-momentum contribution to be evaluated in terms of maps of \\hat T^2 into T^2. The ultraviolet divergences associated with boundaries of moduli space are regularized in a manner that is consistent with the expected duality symmetries of string theory. This leads to an exact expression for terms of order contraction of four Weyl tensors), thereby extending earlier results for the R^4 term that were based on the one-loop eleven-dimensional amplitude. Precise agreement is found with terms in type IIA and IIB superstring theory that arise from the low energy expansion of the tree-level and one-loop string amplitudes and predictions are made for the coefficients of certain two-loop string theory terms as we...

  1. Loop quantum cosmology and singularities.

    Science.gov (United States)

    Struyve, Ward

    2017-08-15

    Loop quantum gravity is believed to eliminate singularities such as the big bang and big crunch singularity. This belief is based on studies of so-called loop quantum cosmology which concerns symmetry-reduced models of quantum gravity. In this paper, the problem of singularities is analysed in the context of the Bohmian formulation of loop quantum cosmology. In this formulation there is an actual metric in addition to the wave function, which evolves stochastically (rather than deterministically as the case of the particle evolution in non-relativistic Bohmian mechanics). Thus a singularity occurs whenever this actual metric is singular. It is shown that in the loop quantum cosmology for a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker space-time with arbitrary constant spatial curvature and cosmological constant, coupled to a massless homogeneous scalar field, a big bang or big crunch singularity is never obtained. This should be contrasted with the fact that in the Bohmian formulation of the Wheeler-DeWitt theory singularities may exist.

  2. PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS

    Energy Technology Data Exchange (ETDEWEB)

    Dahlburg, R. B.; Obenschain, K. [LCP and FD, Naval Research Laboratory, Washington, DC 20375 (United States); Laming, J. M. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Taylor, B. D. [AFRL Eglin AFB, Pensacola, FL 32542 (United States)

    2016-11-10

    Ponderomotive acceleration has been asserted to be a cause of the first ionization potential (FIP) effect, the well-known enhancement in abundance by a factor of 3–4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a “by-product” of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of coronal loops with an axial magnetic field from 0.005 to 0.02 T and lengths from 25,000 to 75,000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets, which act to heat the loop. As a consequence of coronal magnetic reconnection, small-scale, high-speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

  3. Morbidity of temporary loop ileostomies

    NARCIS (Netherlands)

    Bakx, R.; Busch, O. R. C.; Bemelman, W. A.; Veldink, G. J.; Slors, J. F. M.; van Lanschot, J. J. B.

    2004-01-01

    Background/Aims: A temporary loop ileostomy is constructed to protect a distal colonic anastomosis. Closure is usually performed not earlier than 8 - 12 weeks after the primary operation. During this period, stoma-related complications can occur and enhance the adverse effect on quality of life. The

  4. Fuzzy logic controllers and chaotic natural convection loops

    International Nuclear Information System (INIS)

    Theler, German

    2007-01-01

    The study of natural circulation loops is a subject of special concern for the engineering design of advanced nuclear reactors, as natural convection provides an efficient and completely passive heat removal system. However, under certain circumstances thermal-fluid-dynamical instabilities may appear, threatening the reactor safety as a whole.On the other hand, fuzzy logic controllers provide an ideal framework to approach highly non-linear control problems. In the present work, we develop a software-based fuzzy logic controller and study its application to chaotic natural convection loops.We numerically analyse the linguistic control of the loop known as the Welander problem in such conditions that, if the controller were not present, the circulation flow would be non-periodic unstable.We also design a Taka gi-Sugeno fuzzy controller based on a fuzzy model of a natural convection loop with a toroidal geometry, in order to stabilize a Lorenz-chaotic behaviour.Finally, we show experimental results obtained in a rectangular natural circulation loop [es

  5. Chemistry aspects of the Heva and Vercors experimental programmes

    International Nuclear Information System (INIS)

    Leveque, J.P.; Andre, B.; Ducros, G.; Le Marois, G.; Lhiaubet, G.

    1994-01-01

    The HEVA and VERCORS experimental programmes have been carried out of characterise some of the fission products (release rate coefficient, aerosol sizing, chemical species) emitted by nuclear fuel irradiated to approximately 30 GWd/tU and heated up to 2300 K (HEVA) and higher temperatures (VERCORS). Various test parameters were based on those expected in the course of a severe reactor accident. Eight test were performed during the now completed HEVA programme and four tests have been performed in the VERCORS studies. The chemical species recovered in the experimental loop are described with particular emphasis placed on the volatile fission products (caesium, iodine, tellurium), oxides (mainly molybdenum), and the components of the neutron absorbing control rods (silver, indium and cadmium). (authors)

  6. Loop exponent in DNA bubble dynamics

    Science.gov (United States)

    Kaiser, Vojtěch; Novotný, Tomáš

    2014-08-01

    Dynamics of DNA bubbles are of interest for both statistical physics and biology. We present exact solutions to the Fokker-Planck equation governing bubble dynamics in the presence of a long-range entropic interaction. The complete meeting time and meeting position probability distributions are derived from the solutions. Probability distribution functions (PDFs) reflect the value of the loop exponent of the entropic interaction. Our results extend previous results which concentrated mainly on the tails of the PDFs and open a way to determining the strength of the entropic interaction experimentally which has been a matter of recent discussions. Using numerical integration, we also discuss the influence of the finite size of a DNA chain on the bubble dynamics. Analogous results are obtained also for the case of subdiffusive dynamics of a DNA bubble in a heteropolymer, revealing highly universal asymptotics of meeting time and position probability functions.

  7. Design validation and performance of closed loop gas recirculation system

    Science.gov (United States)

    Kalmani, S. D.; Joshi, A. V.; Majumder, G.; Mondal, N. K.; Shinde, R. R.

    2016-11-01

    A pilot experimental set up of the India Based Neutrino Observatory's ICAL detector has been operational for the last 4 years at TIFR, Mumbai. Twelve glass RPC detectors of size 2 × 2 m2, with a gas gap of 2 mm are under test in a closed loop gas recirculation system. These RPCs are continuously purged individually, with a gas mixture of R134a (C2H2F4), isobutane (iC4H10) and sulphur hexafluoride (SF6) at a steady rate of 360 ml/h to maintain about one volume change a day. To economize gas mixture consumption and to reduce the effluents from being released into the atmosphere, a closed loop system has been designed, fabricated and installed at TIFR. The pressure and flow rate in the loop is controlled by mass flow controllers and pressure transmitters. The performance and integrity of RPCs in the pilot experimental set up is being monitored to assess the effect of periodic fluctuation and transients in atmospheric pressure and temperature, room pressure variation, flow pulsations, uniformity of gas distribution and power failures. The capability of closed loop gas recirculation system to respond to these changes is also studied. The conclusions from the above experiment are presented. The validations of the first design considerations and subsequent modifications have provided improved guidelines for the future design of the engineering module gas system.

  8. Vertically Polarized Omnidirectional Printed Slot Loop Antenna

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren H.; Thaysen, Jesper

    2015-01-01

    A novel vertically polarized omnidirectional printed slot loop antenna has been designed, simulated, fabricated and measured. The slot loop works as a magnetic loop. The loop is loaded with inductors to insure uniform and in-phase fields in the slot in order to obtain an omnidirectional radiation...... pattern. The antenna is designed for the 2.45 GHz Industrial, Scientific and Medical band. Applications of the antenna are many. One is for on-body applications since it is ideal for launching a creeping waves due to the polarization.......A novel vertically polarized omnidirectional printed slot loop antenna has been designed, simulated, fabricated and measured. The slot loop works as a magnetic loop. The loop is loaded with inductors to insure uniform and in-phase fields in the slot in order to obtain an omnidirectional radiation...

  9. Spectral analysis, structural elucidation, and evaluation of both nonlinear optical properties and chemical reactivity of a newly synthesized ethyl-3,5-dimethyl-4-[(toluenesulfonyl)-hydrazonomethyl]-1H-pyrrole-2-carboxylate through experimental studies and quantum chemical calculations

    Science.gov (United States)

    Singh, R. N.; Rawat, Poonam

    2013-12-01

    As part of study of hydrazide-hydrazones, we have synthesized ethyl-3,5-dimethyl-4-[(toluenesulfonyl)-hydrazonomethyl]-1H-pyrrole-2-carboxylate (EDTHMPC) and characterized by elemental analysis, FT-IR, UV-Vis, 1H, 13C NMR and Mass spectroscopy. The structure, spectral and thermodynamic parameters of EDTHMPC were quantum chemically calculated performing density functional level theory (DFT) with B3LYP functional and 6-31G (d,p) basis set. Electrophilic charge transfer (ECT) values of interacting molecules indicate that charge flows from p-toluene sulphonyl-hydrazide to ethyl-3,5-dimethyl-4-formyl-1H-pyrrole-2-carboxylate confirming the formation of product by nucleophilic attack. The calculated and experimental wavenumbers analysis confirms the formation of dimer. The calculated changes in thermodynamic quantities during dimer formation in gaseous phase have the negative values for ΔH, ΔG (kcal/mol) and ΔS (cal/mol-K) indicating that the dimer formation is exothermic and will proceed only at low temperature. The strength and nature of hydrogen bonding and weak interactions in dimer have been analyzed by 'Quantum theory of atoms in molecules' (QTAIM) and found to be five types of interactions in which three types are (C⋯N, CH⋯O and CH⋯HC) intramolecular and two types are (CO⋯HN and CH⋯OC) intermolecular. The calculated binding energy of dimer using DFT and QTAIM theory are 14.32 and 15.41 kcal/mol, respectively. The β0 value for monomer is calculated as 11.54 x 10-30 esu indicating microscopic nonlinear optical (NLO) behavior with non-zero values.

  10. Chemical Oscillations

    Indian Academy of Sciences (India)

    The law of mass-action led chemists to the belief that reactions approach equilibrium steadily. So the discovery of chemical oscillations came as a surprise. Now chemists are very familiar with reactions that oscillate in time and/or space. Experimental and theoretical studies of such reac- tions showing temporal and spatial ...

  11. Effect of Interaction between Chromatin Loops on Cell-to-Cell Variability in Gene Expression.

    Directory of Open Access Journals (Sweden)

    Tuoqi Liu

    2016-05-01

    Full Text Available According to recent experimental evidence, the interaction between chromatin loops, which can be characterized by three factors-connection pattern, distance between regulatory elements, and communication form, play an important role in determining the level of cell-to-cell variability in gene expression. These quantitative experiments call for a corresponding modeling effect that addresses the question of how changes in these factors affect variability at the expression level in a systematic rather than case-by-case fashion. Here we make such an effort, based on a mechanic model that maps three fundamental patterns for two interacting DNA loops into a 4-state model of stochastic transcription. We first show that in contrast to side-by-side loops, nested loops enhance mRNA expression and reduce expression noise whereas alternating loops have just opposite effects. Then, we compare effects of facilitated tracking and direct looping on gene expression. We find that the former performs better than the latter in controlling mean expression and in tuning expression noise, but this control or tuning is distance-dependent, remarkable for moderate loop lengths, and there is a limit loop length such that the difference in effect between two communication forms almost disappears. Our analysis and results justify the facilitated chromatin-looping hypothesis.

  12. Estimation of complex permittivity using loop antenna

    DEFF Research Database (Denmark)

    Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

    2004-01-01

    A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna.......A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna....

  13. Verifying parallel loops with separation logic

    NARCIS (Netherlands)

    Blom, Stefan; Darabi, Saeed; Huisman, Marieke

    2014-01-01

    This paper proposes a technique to specify and verify whether a loop can be parallelised. Our approach can be used as an additional step in a parallelising compiler to verify user annotations about loop dependences. Essentially, our technique requires each loop iteration to be specified with the

  14. In, On, or Out of the Loop?

    DEFF Research Database (Denmark)

    Schaub Jr, Gary John; Kristoffersen, Jens Wenzel

    being the degree of sophist ication of weapon responses to external stimuli. Such weapons can be controlled directly with a “man-in-the-loop,” managed by a “man-on-the-loop,” or supervised by a “man-out-of-the-loop.” Although all uses of force by Western militaries take place within an institution...

  15. Theory of K-loops

    CERN Document Server

    Kiechle, Hubert

    2002-01-01

    The book contains the first systematic exposition of the current known theory of K-loops, as well as some new material. In particular, big classes of examples are constructed. The theory for sharply 2-transitive groups is generalized to the theory of Frobenius groups with many involutions. A detailed discussion of the relativistic velocity addition based on the author's construction of K-loops from classical groups is also included. The first chapters of the book can be used as a text, the later chapters are research notes, and only partially suitable for the classroom. The style is concise, but complete proofs are given. The prerequisites are a basic knowledge of algebra such as groups, fields, and vector spaces with forms.

  16. Loop connectors in dentogenic diastema

    Directory of Open Access Journals (Sweden)

    Sanjna Nayar

    2015-01-01

    Full Text Available Patients with a missing tooth along with diastema have limited treatment options to restore the edentulous space. The use of a conventional fixed partial denture (FPD to replace the missing tooth may result in too wide anterior teeth leading to poor esthetics. Loss of anterior teeth with existing diastema may result in excess space available for pontic. This condition presents great esthetic challenge for prosthodontist. If implant supported prosthesis is not possible because of inadequate bone support, FPD along with loop connector may be a treatment option to maintain the diastema and provide optimal esthetic restoration. Here, we report a clinical case where FPD along with loop connector was used to achieve esthetic rehabilitation in maxillary anterior region in which midline diastema has been maintained.

  17. Experimental and analytical studies of merging plasma loops on the Caltech solar loop experiment

    Science.gov (United States)

    Pitigoi-Aron, Gabriela

    Attracting and retaining strong faculty members in dental schools have long been challenges in the United States. Faced with an emerging crisis in the availability and quality of dental educators, many researchers have focused on analyzing data and trends related to this subject. Even though there are substantial studies that provide a picture of why domestic dentists choose to become dental educators, there are no dedicated studies investigating why foreign-educated dentists want to become dental educators. This distinct area is of particular importance as we witness increasing diversity of patients and an increased need for a more diverse health care workforce. The purpose of this study was to analyze the reasons why foreign-educated dentists became dental educators in United States and furthermore, at University of the Pacific Arthur A. Dugoni School of Dentistry in San Francisco, California. The research data was collected by means of surveys and in-depth interviews of foreign-trained faculty and IDS graduates on staff at Pacific. The data analysis was performed using descriptive statistics for the survey and a process of thematic analysis for interviews. The surveys' analysis yielded the following six factors that most positively influenced foreign-educated dentists in deciding to embrace a career as an academic educator: (1) Intellectual challenges and stimulation; (2) Opportunity to always be on the cutting edge; (3) Interest in science, new discovery, exploration; (4) Opportunity for regular interaction with other faculty dentists; (5) Desire to be a teacher. (6) Collegial environment of the university. There were two most negative factors identified, as follows: (1) Income differential compared to private practice; (2) Pressure to generate income for the university. Corroborated by analysis of the interviews, the following themes emerged: (1) Drive for research; (2) Desire to be on cutting edge. (3) Desire to share knowledge through teaching; (4) Social and personal factors and perceptions with emphasis on mentors' influence; (5) Negative influence of salary difference with respect to private practitioners. The findings of this study were similar to the available studies on foreign-trained dentists and to most of the studies already done on domestically trained dentists. The major factors found were comparable with the up-to-date literature. The elevated research drive, the intellectual challenges, the work environment, the desire to teach, and the mentors' influence were among those which mirrored almost perfectly the other studies. Some fine differences were found for foreign-trained dentists, such as a lighter financial burden caused by smaller student debt and the irrelevance of military practice experience. The study provides a number of suggestions for enhancing the recruiting and retaining process for dental academia: (1) Support and enhance the research capacity of dental schools; (2) Create structures to develop mentors; (3) Invest to build prestige; (4) Find creative ways to offset lower salaries; (5) Foster a pleasant academic working environment; (6) Use international activities to recruit international dentists. The study revealed factors that have been influential in participants' decisions to choose an academic career, in general and at Pacific. It is hoped that this study will be a useful reference in the increasingly difficult endeavor of adding and retaining world-class dental educators.

  18. Laboratory of Chemical Physics

    Data.gov (United States)

    Federal Laboratory Consortium — Current research in the Laboratory of Chemical Physics is primarily concerned with experimental, theoretical, and computational problems in the structure, dynamics,...

  19. Closed-Loop Neuromorphic Benchmarks

    Directory of Open Access Journals (Sweden)

    Terrence C Stewart

    2015-12-01

    Full Text Available Evaluating the effectiveness and performance of neuromorphic hardware is difficult. It is evenmore difficult when the task of interest is a closed-loop task; that is, a task where the outputfrom the neuromorphic hardware affects some environment, which then in turn affects thehardware’s future input. However, closed-loop situations are one of the primary potential uses ofneuromorphic hardware. To address this, we present a methodology for generating closed-loopbenchmarks that makes use of a hybrid of real physical embodiment and a type of minimalsimulation. Minimal simulation has been shown to lead to robust real-world performance, whilestill maintaining the practical advantages of simulation, such as making it easy for the samebenchmark to be used by many researchers. This method is flexible enough to allow researchersto explicitly modify the benchmarks to identify specific task domains where particular hardwareexcels. To demonstrate the method, we present a set of novel benchmarks that focus on motorcontrol for an arbitrary system with unknown external forces. Using these benchmarks, we showthat an error-driven learning rule can consistently improve motor control performance across arandomly generated family of closed-loop simulations, even when there are up to 15 interactingjoints to be controlled.

  20. Results from tests of TFL Hydragard sampling loop

    International Nuclear Information System (INIS)

    Steimke, J.L.

    1995-03-01

    When the Defense Waste Processing Facility (DWPF) is operational, processed radioactive sludge will be transferred in batches to the Slurry Mix Evaporator (SME), where glass frit will be added and the contents concentrated by boiling. Batches of the slurry mixture are transferred from the SME to the Melter Feed Tank (MFT). Hydragard reg-sign sampling systems are used on the SME and the MFT for collecting slurry samples in vials for chemical analysis. An accurate replica of the Hydragard sampling system was built and tested in the thermal Fluids Laboratory (TFL) to determine the hydragard accuracy. It was determined that the original Hydragard valve frequently drew a non-representative sample stream through the sample vial that ranged from frit enriched to frit depleted. The Hydragard valve was modified by moving the plunger and its seat backwards so that the outer surface of the plunger was flush with the inside diameter of the transfer line when the valve was open. The slurry flowing through the vial accurately represented the composition of the slurry in the reservoir for two types of slurries, different dilution factors, a range of transfer flows and a range of vial flows. It was then found that the 15 ml of slurry left in the vial when the Hydragard valve was closed, which is what will be analyzed at DWPF, had a lower ratio of frit to sludge as characterized by the lithium to iron ratio than the slurry flowing through it. The reason for these differences is not understood at this time but it is recommended that additional experimentation be performed with the TFL Hydragard loop to determine the cause

  1. Protein loop modeling using a new hybrid energy function and its application to modeling in inaccurate structural environments.

    Directory of Open Access Journals (Sweden)

    Hahnbeom Park

    Full Text Available Protein loop modeling is a tool for predicting protein local structures of particular interest, providing opportunities for applications involving protein structure prediction and de novo protein design. Until recently, the majority of loop modeling methods have been developed and tested by reconstructing loops in frameworks of experimentally resolved structures. In many practical applications, however, the protein loops to be modeled are located in inaccurate structural environments. These include loops in model structures, low-resolution experimental structures, or experimental structures of different functional forms. Accordingly, discrepancies in the accuracy of the structural environment assumed in development of the method and that in practical applications present additional challenges to modern loop modeling methods. This study demonstrates a new strategy for employing a hybrid energy function combining physics-based and knowledge-based components to help tackle this challenge. The hybrid energy function is designed to combine the strengths of each energy component, simultaneously maintaining accurate loop structure prediction in a high-resolution framework structure and tolerating minor environmental errors in low-resolution structures. A loop modeling method based on global optimization of this new energy function is tested on loop targets situated in different levels of environmental errors, ranging from experimental structures to structures perturbed in backbone as well as side chains and template-based model structures. The new method performs comparably to force field-based approaches in loop reconstruction in crystal structures and better in loop prediction in inaccurate framework structures. This result suggests that higher-accuracy predictions would be possible for a broader range of applications. The web server for this method is available at http://galaxy.seoklab.org/loop with the PS2 option for the scoring function.

  2. Boosted PWM open loop control of hydraulic proportional valves

    International Nuclear Information System (INIS)

    Amirante, R.; Innone, A.; Catalano, L.A.

    2008-01-01

    This paper presents an innovative open loop control technique for direct single stage hydraulic proportional valves whose response rate is significantly higher than that obtained by standard open loop control techniques, even comparable to more costly commercial closed loop systems. Different from standard open loop techniques, which provide the coil with a constant current proportional to the target position, the control strategy proposed in this paper employs the peak and hold (P and H) technique, widely used in Diesel engine modern supply systems, to boost the duty cycle value of the pulse width modulation (PWM) signal for a short time, namely during the spool displacement, while maintaining a lower duty cycle for holding the spool in the required opening position. The developed 'boosted PWM' technique only requires a low cost microcontroller, such as a peripheral interface controller (PIC) equipped with a metal oxide semiconductor (MOS) power driver. The PWM parameters are calibrated as a function of the spool displacement so as to maximize the response rate without introducing overshoots: the collected data are stored in the PIC. Different valve opening procedures with step response have been compared to demonstrate the merits of the proposed boosted PWM technique. No overshoots have been registered. Moreover, the proposed method is characterized by a significantly higher response rate with respect to a standard open loop control, which approximately has the same cost. Similar experimental tests show that the proposed boosted PWM technique has a response rate even higher than that provided by the more costly commercial closed loop system mounted on the valve, and it produces no overshoots

  3. Optimized atomic statistical potentials: assessment of protein interfaces and loops.

    Science.gov (United States)

    Dong, Guang Qiang; Fan, Hao; Schneidman-Duhovny, Dina; Webb, Ben; Sali, Andrej

    2013-12-15

    Statistical potentials have been widely used for modeling whole proteins and their parts (e.g. sidechains and loops) as well as interactions between proteins, nucleic acids and small molecules. Here, we formulate the statistical potentials entirely within a statistical framework, avoiding questionable statistical mechanical assumptions and approximations, including a definition of the reference state. We derive a general Bayesian framework for inferring statistically optimized atomic potentials (SOAP) in which the reference state is replaced with data-driven 'recovery' functions. Moreover, we restrain the relative orientation between two covalent bonds instead of a simple distance between two atoms, in an effort to capture orientation-dependent interactions such as hydrogen bonds. To demonstrate this general approach, we computed statistical potentials for protein-protein docking (SOAP-PP) and loop modeling (SOAP-Loop). For docking, a near-native model is within the top 10 scoring models in 40% of the PatchDock benchmark cases, compared with 23 and 27% for the state-of-the-art ZDOCK and FireDock scoring functions, respectively. Similarly, for modeling 12-residue loops in the PLOP benchmark, the average main-chain root mean square deviation of the best scored conformations by SOAP-Loop is 1.5 Å, close to the average root mean square deviation of the best sampled conformations (1.2 Å) and significantly better than that selected by Rosetta (2.1 Å), DFIRE (2.3 Å), DOPE (2.5 Å) and PLOP scoring functions (3.0 Å). Our Bayesian framework may also result in more accurate statistical potentials for additional modeling applications, thus affording better leverage of the experimentally determined protein structures. SOAP-PP and SOAP-Loop are available as part of MODELLER (http://salilab.org/modeller).

  4. Modular invariance and covariant loop calculus

    International Nuclear Information System (INIS)

    Petersen, J.L.; Roland, K.O.; Sidenius, J.R.

    1988-01-01

    The covariant loop calculus provides an efficient technique for computing explicit expressions for the density on moduli space corresponding to arbitrary (bosonic string) loop diagrams. Since modular invariance is not manifest, however, we carry out a detailed comparison with known explicit two- and three-loop results derived using analytic geometry (one loop is known to be okay). We establish identity to 'high' order in some moduli and exactly in others. Agreement is found as a result of various nontrivial cancellations, in part related to number theory. We feel our results provide very strong support for the correctness of the covariant loop calculus approach. (orig.)

  5. Modular invariance and covariant loop calculus

    International Nuclear Information System (INIS)

    Petersen, J.L.; Roland, K.O.; Sidenius, J.R.

    1988-01-01

    The covariant loop calculus provides and efficient technique for computing explicit expressions for the density on moduli space corresponding to arbitrary (bosonic string) loop diagrams. Since modular invariance is not manifest, however, we carry out a detailed comparison with known explicit 2- and 3- loop results derived using analytic geometry (1 loop is known to be ok). We establish identity to 'high' order in some moduli and exactly in others. Agreement is found as a result of various non-trivial cancellations, in part related to number theory. We feel our results provide very strong support for the correctness of the covariant loop calculus approach. (orig.)

  6. SOLA-LOOP analysis of a back pressure check valve

    International Nuclear Information System (INIS)

    Travis, J.R.

    1984-01-01

    The SOLA-LOOP computer code for transient, nonequilibrium, two-phase flows in networks has been coupled with a simple valve model to analyze a feedwater pipe breakage with a back-pressure check valve. Three tests from the Superheated Steam Reactor Safety Program Project (PHDR) at Kahl, West Germany, are analyzed, and the calculated transient back-pressure check valve behavior and fluid dynamics effects are found to be in excellent agreement with the experimentally measured data

  7. Dynamic Looping of a Free-Draining Polymer

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Felix X. -F.; Stinis, Panos; Qian, Hong

    2018-01-01

    In order to investigate analytically the looping time of a free-draining polymer (Rouse model), we revisit the celebrated Wilemski-Fixman (WF) theory. The WF theory introduces a sink term in the Fokker-Planck equation to account for the complicated boundary condition satisfied by the looping effect. We use perturbation methods to make theoretical predictions of the looping time for two popular choices for the sink, namely the Delta and Heaviside sinks. For both types of sink, we show that under the condition of small capture radius (compared to the Kuhn length), WF can produce all known analytical and asymptotic results obtained by other means. This includes the mixed scaling regime which combines Doi's N2 scaling and Szabo, Schulten & Schulten's N√N/ɑ scaling. In addition, again for the case of small capture radius, we find an extra term in the analytical expression for the looping time which has not appeared previously in the literature. Numerical results obtained through Monte Carlo simulations corroborate the theoretical findings. The mathematical constructions developed here can be applied to other diffusion limited catalytically activated chemical reactions.

  8. Loop technique for mitral valve repair.

    Science.gov (United States)

    Shibata, Toshihiko

    2014-02-01

    A new artificial chordal reconstruction technique has been developed using several expanded polytetrafluoroethylene (ePTFE) loops. This technique differs from conventional artificial chordal reconstruction in the use of premeasured ePTFE loops. The loop technique involves several steps: (1) assessment of the corresponding papillary muscle; (2) measurement of the required ePTFE loop length; (3) making a loop set of the premeasured length; (4) anchoring the loop set to the papillary muscle; (5) fixing the ePTFE loops to the prolapsing leaflet; (6) adjusting the loop length if necessary; and (7) ring implantation. Favorable early and mid-term results of this loop technique have been reported in patients undergoing mitral valve repair through mini-thoracotomy and via median sternotomy, with 3-year survival and re-operation-free rates of 94.8 and 97.4 %, respectively. The loop technique using ePTFE chordal reconstruction with premeasured loops thus appears to be a safe, reliable, and reproducible technique for mitral valve repair. In addition, it is suitable for both minimally invasive and conventional sternotomy approaches, and represents a useful technique for treating posterior, anterior, and especially bi-leaflet prolapses.

  9. experimental validation of a dual loop control of two phases

    African Journals Online (AJOL)

    Kraa O, Ghodbane H, Saadi R, Ayad M.Y, Becherif M, Bahri M and Aboubou A

    2016-05-01

    May 1, 2016 ... Industrial Hybrid Vehicle Applications, France. 3. FCLab FR CNRS 3539, ... vehicles, solid electrolyte and favorable power-to-weight ratio offer an order of magnitude higher power density than ... ripple which is one of the most important required characteristics from DC/DC converters for FC electric vehicle ...

  10. Hyperstaticity and loops in frictional granular packings

    Science.gov (United States)

    Tordesillas, Antoinette; Lam, Edward; Metzger, Philip T.

    2009-06-01

    The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum of frictional forces around each loop. For even loops, the latent stresses are interior and are characterized by the alternating sum of frictional forces around each loop. The statistics of these two types of loop sums are found to be Gibbsian with a "temperature" that is linear with the friction coefficient μ when μ<1.

  11. Fast protein loop sampling and structure prediction using distance-guided sequential chain-growth Monte Carlo method.

    Directory of Open Access Journals (Sweden)

    Ke Tang

    2014-04-01

    Full Text Available Loops in proteins are flexible regions connecting regular secondary structures. They are often involved in protein functions through interacting with other molecules. The irregularity and flexibility of loops make their structures difficult to determine experimentally and challenging to model computationally. Conformation sampling and energy evaluation are the two key components in loop modeling. We have developed a new method for loop conformation sampling and prediction based on a chain growth sequential Monte Carlo sampling strategy, called Distance-guided Sequential chain-Growth Monte Carlo (DISGRO. With an energy function designed specifically for loops, our method can efficiently generate high quality loop conformations with low energy that are enriched with near-native loop structures. The average minimum global backbone RMSD for 1,000 conformations of 12-residue loops is 1:53 A° , with a lowest energy RMSD of 2:99 A° , and an average ensembleRMSD of 5:23 A° . A novel geometric criterion is applied to speed up calculations. The computational cost of generating 1,000 conformations for each of the x loops in a benchmark dataset is only about 10 cpu minutes for 12-residue loops, compared to ca 180 cpu minutes using the FALCm method. Test results on benchmark datasets show that DISGRO performs comparably or better than previous successful methods, while requiring far less computing time. DISGRO is especially effective in modeling longer loops (10-17 residues.