WorldWideScience

Sample records for based chemical looping

  1. A Polygeneration System Based on Multi-Input Chemical Looping Combustion

    Directory of Open Access Journals (Sweden)

    Xiaosong Zhang

    2014-11-01

    Full Text Available This paper proposes a polygeneration system based on a multi-input chemical looping combustion system, which generates methanol and electricity, through the use of natural gas and coal. In this system, the chemical looping hydrogen (CLH production system and the coal-based methanol production system are integrated. A high quality fuel, natural gas, is used to improve the conversion ratio of coal. The Gibbs energy of the two kinds of fuels is fully used. Benefitting from the chemical looping process, 27% CO2 can be captured without energy penalty. With the same outputs of methanol and electricity, the energy savings ratio of the new system is about 12%. Based on the exergy analyses, it is disclosed that the integration of synthetic utilization of natural gas and coal plays a significant role in reducing the exergy destruction of the new system. The promising results obtained in this paper may lead to a clean coal technology that will utilize natural gas and coal more efficiently and economically.

  2. Thermal Analysis and Investigation of NiO-Based Oxygen Carriers for Chemical-Looping Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jerndal, Erik, e-mail: erik.jerndal@chalmers.se

    2009-03-15

    Capture and storage of CO{sub 2} can be used to reduce greenhouse gas emissions from combustion of fossil fuels. Chemical-looping combustion is a two-step combustion process where CO{sub 2} is obtained in a separate stream, ready for compression and storage. The technology uses circulating oxygen carriers to transfer oxygen from an air reactor to a fuel reactor, thus avoiding an energy consuming gas separation unit. A thermal analysis of the process using a large number of possible oxygen carriers was performed by simulating chemical reactions. Based on the ability of the oxygen carriers to convert different gaseous fuels, stability in air and melting temperature some metal oxides based on Ni, Cu, Fe, Mn, Co, W and sulphates of Ba, Sr and Ca showed good thermodynamic properties and could be feasible as oxygen carriers. The promising systems were investigated further with respect to temperature changes in the fuel reactor as well as possible formation of carbon, sulphides and sulphates which may deactivate the oxygen carriers. Oxygen carriers of NiO, supported by NiAl{sub 2}O{sub 4}, were prepared and investigated experimentally with respect to parameters important for chemical-looping combustion. These oxygen carriers were based on commercially available raw materials in contrast to most of the previously tested oxygen carriers, which have been prepared from pure chemicals. Further, it was investigated if spray-drying, which is a production method suitable for large-scale particle preparation, can be used to produce high performing oxygen carriers instead of the small-scale freeze-granulation method. Generally, materials prepared from commercially available raw material showed high reactivity with methane and oxygen. Oxygen carriers prepared by spray-drying, displayed a remarkable similarity when compared to oxygen carriers prepared from the same starting material by freeze-granulation, both regarding physical properties and reactivity. Further, the up-scaling of

  3. 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.

  4. Integration of calcium and chemical looping combustion using composite CaO/CuO-based materials.

    Science.gov (United States)

    Manovic, Vasilije; Anthony, Edward J

    2011-12-15

    Calcium looping cycles (CaL) and chemical looping combustion (CLC) are two new, developing technologies for reduction of CO(2) emissions from plants using fossil fuels for energy production, which are being intensively examined. Calcium looping is a two-stage process, which includes oxy-fuel combustion for sorbent regeneration, i.e., generation of a concentrated CO(2) stream. This paper discuss the development of composite materials which can use copper(II)-oxide (CuO) as an oxygen carrier to provide oxygen for the sorbent regeneration stage of calcium looping. In other words, the work presented here involves integration of calcium looping and chemical looping into a new class of postcombustion CO(2) capture processes designated as integrated CaL and CLC (CaL-CLC or Ca-Cu looping cycles) using composite pellets containing lime (CaO) and CuO together with the addition of calcium aluminate cement as a binder. Their activity was tested in a thermogravimetric analyzer (TGA) during calcination/reduction/oxidation/carbonation cycles. The calcination/reduction typically was performed in methane (CH(4)), and the oxidation/carbonation stage was carried out using a gas mixture containing both CO(2) and O(2). It was confirmed that the material synthesized is suitable for the proposed cycles; with the very favorable finding that reduction/oxidation of the oxygen carrier is complete. Various schemes for the Ca-Cu looping process have been explored here that would be compatible with these new composite materials, along with some different possibilities for flow directions among carbonator, calciner, and air reactor.

  5. Conceptual design of a Ni-based chemical looping combustion process using fixed-beds

    International Nuclear Information System (INIS)

    Highlights: • The feasibility of fixed-bed CLC with methane and Ni-based carriers is assessed. • A conceptual design has determined operating windows for each stage of the system. • Low O2 content and low inlet gas temperature limit temperature in oxidation front. • Results show technical viability of fixed-bed CLC and its potential for further development. - Abstract: This work presents a comprehensive conceptual design of a Ni-based chemical looping combustion process (CLC) carried out in fixed bed reactors. The process is intended to exploit the well-known advantages of the Ni/NiO redox system for CLC applications in terms of high reactivity, O2 carrying capacity and chemical and thermal stability. Solutions to the problem of heat management in fixed bed reactors at high temperature and high pressure are described, while a continuous flow of nitrogen for driving a gas turbine is produced. Each reactor involved in the process goes through a cyclic sequence of five reaction and heat transfer stages. Cool product gas recirculations are incorporated into the Ni oxidation and NiO reduction stages in order to moderate the maximum temperatures in the beds and control the displacement of the reaction and heat transfer fronts. A preliminary conceptual design of the process has been carried out to determine the minimum number of reactors needed for continuous operation in typical large-scale CO2 capture systems. Basic reactor models and assumptions based on an ideal plug flow pattern have been used in all the reactors during the chemical reactions and the heat transfer operations. This has made it possible to identify reasonable operating windows for the eight fixed-bed reactors that make up the CO2 capture system, and has demonstrated not only its technical viability but also its great potential for further development

  6. Performance of Ni-based, Fe-based and Co-based Oxygen Carriers in Chemical-Looping Hydrogen Generation

    Institute of Scientific and Technical Information of China (English)

    Liang Hao; Zhang Xiwen; Fang Xiangchen; Yuan Honggang

    2013-01-01

    Ni-based, Fe-based and Co-based oxygen carriers with perovskite oxides used as the supports were prepared by citric acid complexation method. The oxygen carriers were characterized by thermal analysis, H2-temperature-programmed reduction and X-ray diffraction methods. Performance tests were evaluated through Chemical-Looping Hydrogen Genera-tion in a ifxed-bed reactor operating at atmospheric pressure. The characterization results showed that all samples were composed of metal oxides and perovskite oxides. Performance results indicated that CH4 conversion over the oxygen car-riers decreased in the following order:NiO/LaNiO3>Co2O3/LaCoO3>Fe2O3/LaFeO3. The ability of NiO/LaNiO3 and Fe2O3/LaFeO3 to decompose water was stronger than that of Co2O3/LaCoO3 as evidenced by our experiments. H2 amounting to 80 mL upon reacting on methane in every cycle could be completely oxidized by NiO/LaNiO3 at 900℃in the period from the third cycle to the eighth cycle.

  7. 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.

  8. 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

  9. Performance of coal fly-ash based oxygen carrier for the chemical looping combustion of synthesis gas

    International Nuclear Information System (INIS)

    Highlights: • Fly-ash based oxygen carriers were synthesised for chemical looping combustion of synthesis gas. • Using fly-ash as the support of the oxygen carrier enhanced the thermal stability and oxidant transfer for fuel oxidation. • Fly-ash based nickel oxide reformed hydrocarbons into carbon monoxide with the presence of carbon dioxide. - Abstract: The performance of coal fly-ash based oxygen carriers for chemical looping combustion of synthesis gas has been investigated using both a thermogravimetric analyser and a packed bed reactor. Oxygen carriers with 50 wt% active metal compounds, including copper, nickel and iron oxides, supported on coal fly-ash were synthesised using the deposition–precipitation method. Copper oxide and nickel oxide supported on fly-ash showed high oxygen transfer efficiency and oxygen carrying capacity at 800 °C. The fly-ash based nickel oxide was effective in reforming hydrocarbons and for the conversion of carbon dioxide into carbon monoxide; a nickel complex with silicate was identified as a minor phase following the reduction reaction. The fly-ash based iron oxide showed various reduction steps and resulted in an extended reduction time. The carbon emission at the oxidation stage was avoided by reducing the length of the exposure to the reduction gas

  10. 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

  11. Investigation into Syngas Generation from Solid Fuel Using CaSO4-based Chemical Looping Gasification Process

    Institute of Scientific and Technical Information of China (English)

    LIU Yongzhuo; GUO Qingjie

    2013-01-01

    Chemical-looping gasification(CLG)is a novel process for syngas generation from solid fuels,sharing the same basic principles as chemical-looping combustion(CLC).It also uses oxygen carriers(mainly metal oxide and calcium sulfate)to transfer heat and oxygen to the fuel.In this paper,the primary investigation into the CLG process with CaSO4 as oxygen carrier was carried out by thermodynamic analysis and experiments in the tube reactor.Sulfur-contained gas emission was mainly H2S rather than SO2 in the CLG process,showing some different features from the CLC.The mass and heat balance of CLG processes were calculated thermodynamically to determinate the auto-thermal operating conditions with different CaSO4/C and steam/C molar ratios.It was found that the CaSO4/C molar ratio should be higher than 0.2 to reach auto-thermal balance.The effect of temperature on the reactions between oxygen carrier and coal was investigated based on Gibbs free energy minimum method and experimental results.It indicated that high temperature favored the CLG process in the fuel reactor and part of syngas was consumed to compensate for auto-thermal system.

  12. Synthesis of iron-based chemical looping sorbents integrated with pH swing carbon mineral sequestration.

    Science.gov (United States)

    Kim, Hyung Ray; Lee, Dong Hyun; Fan, Liang-Shih; Park, Ah-Hyung Alissa

    2009-12-01

    The previously developed pH swing carbon mineral sequestration immobilizes the gaseous CO2 into a thermodynamically stable solid, MgCO3, using Mg-bearing minerals such as serpentine. This mineral carbonation technology is particularly promising since it generates value-added solid products: high surface area silica, iron oxide, and magnesium carbonate, while providing a safe and permanent storage option for CO2. By carefully controlling the pH of the system, these solids products can be produced with high purity. This study focuses on the synthesis of iron oxide particles as a chemical looping sorbent in order to achieve the integration between carbon capture and storage technologies. Since the solubility of Fe in aqueous phase is relatively low at neutral pH, the effect of the weak acid and chelating agents on the extraction of Fe from serpentine was investigated. The synthesized iron-based chemical looping sorbent was found to be as effective as commercially available iron oxide nanoparticles at converting syngas into high purity H2, while producing a sequestration-ready CO2 stream. PMID:19908801

  13. 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

  14. 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.

  15. Design and evaluation of an IGCC power plant using iron-based syngas chemical-looping (SCL) combustion

    International Nuclear Information System (INIS)

    Highlights: • A new concept for power generation including carbon capture was found. • The air reactor temperature significantly influences the net efficiency. • The use of a CO2 turbine decreases the net efficiency. • Compared to a conventional IGCC with 90% CO2 capture the net efficiency increases. - Abstract: Chemical-looping combustion (CLC) is a novel and promising combustion technology with inherent separation of the greenhouse gas CO2. This paper focuses on the design and thermodynamic evaluation of an integrated gasification combined-cycle (IGCC) process using syngas chemical looping (SCL) combustion for generating electricity. The syngas is provided by coal gasification; the gas from the gasifier is cleaned using high-temperature gas desulfurization (HGD). In this study, the oxygen carrier iron oxide (Fe2O3) is selected to oxidize the syngas in a multistage moving-bed reactor. The resulting reduced iron particles then consist of FeO and Fe3O4. To create a closed-cycle operation, these particles are partially re-oxidized with steam in a fluidized-bed regenerator to pure Fe3O4 and then fully re-oxidized in a fluidized-bed air combustor to Fe2O3. One advantage of this process is the co-production of hydrogen diluted with water vapor within the steam regenerator. Both the HGD and CLC systems are not under commercial operation so far. This mixture is fed to a gas turbine for the purpose of generating electricity. The gas turbine is expected to exhibit low NOx emissions due to the high ratio of water in the combustion chamber. Cooling the flue gas in the HRSG condenses the water vapor to yield high-purity CO2 for subsequent compression and disposal. To evaluate the net efficiency, two conventional syngas gasifiers are considered, namely the BGL slagging gasifier and the Shell entrained-flow gasifier. The option of using a CO2 turbine after the SCL-fuel reactor is also investigated. A sensitivity analysis is performed on the SCL-air reactor outlet

  16. Utilization of chemical looping strategy in coal gasification processes

    Institute of Scientific and Technical Information of China (English)

    Liangshih Fan; Fanxing Li; Shwetha Ramkumar

    2008-01-01

    Three chemical looping gasification processes, i. e. Syngas Chemical Looping (SCL) process, Coal Direct Chemical Looping (CDCL) process, and Calcium Looping process (CLP), are being developed at the Ohio State University (OSU). These processes utilize simple reaction schemes to convert carbonaceous fuels into products such as hydrogen, electricity, and synthetic fuels through the transformation of a highly reactive, highly recyclable chemical intermediate. In this paper, these novel chemical looping gasification processes are described and their advantages and potential challenges for commercialization are discussed.

  17. Chemical Looping Combustion of Rice Husk

    Directory of Open Access Journals (Sweden)

    Rashmeet Singh Monga

    2015-05-01

    Full Text Available A thermodynamic investigation of direct chemical looping combustion (CLC of rice husk is presented in this paper. Both steam and CO2 are used for gasification within the temperature range of 500–1200˚C and different amounts of oxygen carriers. Chemical equilibrium model was considered for the CLC fuel reactor. The trends in product compositions of the fuel reactor, were determined. Rice husk gasification using 3 moles H2O and 0 moles CO2 per mole carbon (in rice husk at 1 bar pressure and 900˚C was found to be the best operating point for hundred percent carbon conversion in the fuel reactor. Such detailed thermodynamic studies can be useful to design chemical looping combustion processes using different fuels.

  18. 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

    Chemical Looping Combustion (CLC) is one promising fuel-combustion technology, which can facilitate economic CO{sub 2} 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 topical report discusses the results of four complementary efforts: (5.1) the development of process and economic models to optimize important design considerations, such as oxygen carrier circulation rate, temperature, residence time; (5.2) the development of high-performance simulation capabilities for fluidized beds and the collection, parameter identification, and preliminary verification/uncertainty quantification; (5.3) the exploration of operating characteristics in the laboratoryscale bubbling bed reactor, with a focus on the oxygen carrier performance, including reactivity, oxygen carrying capacity, attrition resistance, resistance to deactivation, cost and availability; and (5.4) the identification of kinetic data for copper-based oxygen carriers as well as the development and analysis of supported copper oxygen carrier material. Subtask 5.1 focused on the development of kinetic expressions for the Chemical Looping with Oxygen Uncoupling (CLOU) process and validating them with reported literature data. The kinetic expressions were incorporated into a process model for determination of reactor size and oxygen carrier circulation for the CLOU process using ASPEN PLUS. An ASPEN PLUS process model was also developed using literature data for the CLC process employing an iron-based oxygen carrier, and the results of the process model have been utilized to perform a relative economic comparison. In Subtask 5.2, the investigators studied the trade-off between modeling approaches and available simulations tools. They quantified uncertainty in the high-performance computing (HPC) simulation tools for CLC bed applications. Furthermore

  19. Development on iron-based moving bed chemical looping process%铁基移动床化学链技术进展

    Institute of Scientific and Technical Information of China (English)

    许迪恺; Tong Andrew; 曾亮; 罗四维; 范良士

    2014-01-01

    在日益增长的能源需求与日益严峻的全球气候变化带来的双重压力下,清洁、高效且经济的能源利用方法显得尤为重要。将化学链概念用于传统化石能源的转化是一种前景广阔的新技术。化学链燃烧利用载氧体间接转化含碳燃料,同时实现二氧化碳的捕集。俄亥俄州立大学研发了采用铁基载氧体和移动床反应器的化学链技术,可实现天然气、煤、生物质等多种燃料向电力、氢、液体燃料等产品的零排放转化。目前,合成气化学链(syngas chemical looping, SCL)和煤直接化学链(coal direct chemical looping, CDCL)技术两套25 kWth级小试装置已成功运行总计超过850 h,一套250 kWth级的高压SCL装置即将投入示范运行。%Driven by increasing demands for energy and concerns for climate change, more attention are paid to the development of clean, efficient, and economical technologies for energy conversion, among which chemical looping is considered as a promising alternative for fossil fuel conversion. Chemical looping processes enable highly efficient in situ CO2 capture in oxidation of carbonaceous fuels by making use of solid oxygen carriers. The Ohio State University (OSU) has developed a unique chemical looping technology utilizing iron-based oxygen carrier and moving bed reactors. Thermodynamic analysis shows that counter-current moving bed reactor can maximize oxygen carrier conversion while fully converting fuels, enabling high purity H2 production by iron-steam reaction. OSU chemical looping is highly flexible for converting a variety of gaseous and solid fuels to electricity, H2, and chemicals with CO2 captured. To date, the syngas chemical looping (SCL) technology and the coal direct chemical looping technology has been successfully operated for more than 850 h in total on two 25 kWth sub-pilot units. A 250 kWth high pressure SCL pilot unit is constructed at National Carbon Capture Center

  20. Chemical Looping Combustion of Rice Husk

    OpenAIRE

    Rashmeet Singh Monga; Ganesh R. Kale

    2015-01-01

    A thermodynamic investigation of direct chemical looping combustion (CLC) of rice husk is presented in this paper. Both steam and CO2 are used for gasification within the temperature range of 500–1200˚C and different amounts of oxygen carriers. Chemical equilibrium model was considered for the CLC fuel reactor. The trends in product compositions of the fuel reactor, were determined. Rice husk gasification using 3 moles H2O and 0 moles CO2 per mole carbon (in rice husk) at 1 bar pr...

  1. Packed Bed Reactor Technology for Chemical-Looping Combustion

    NARCIS (Netherlands)

    Noorman, Sander; Sint Annaland, van Martin; Kuipers, Hans

    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 expressi

  2. Experimental validation of packed bed chemical-looping combustion

    NARCIS (Netherlands)

    Noorman, S.; Sint Annaland, van 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

  3. 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.

  4. 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

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

    OpenAIRE

    He Fang; Li Haibin; Zhao Zengli

    2009-01-01

    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 dur...

  6. Parametric and dynamic studies of an iron-based 25-kWth coal direct chemical looping unit using sub-bituminous coal

    International Nuclear Information System (INIS)

    Highlights: • Integrated, moving bed chemical looping reactor with iron-oxide based oxygen carrier. • Coal carbon conversion from 84.8% to 99.9%, thermal capacity 7.4 to 27.7 kWth, O2 demand less than 1.3%. • Dynamic temperature of moving bed reducer is established and tracked during coal injection. • CH4 and CO present at initial coal injection, eliminated after oxygen carrier activated. • Lower coal injection had higher volatiles residence time and conversion. - Abstract: The iron-based Coal-Direct Chemical Looping (CDCL) combustion process is an alternative to conventional oxy-combustion technologies, where the oxygen used for fuel conversion in the CDCL process is provided by an iron-oxide based oxygen carrier instead of an air separation unit. The iron oxide is reduced using coal in the reducer reactor, producing highly-pure CO2 in the flue gas, and the reduced iron oxide is regenerated in a separate combustor reactor using air. The CDCL process at Ohio State has been developed and demonstrated in a 25 kWth sub-pilot unit, and it is the first chemical looping demonstration unit with a circulating moving bed reactor for solid fuel conversion. To date, the CDCL sub-pilot unit at OSU has been operated for more than 680 h, with a 200-h continuous operation, providing important data on long term operability as well as parametric optimization. This paper discusses recent parametric operational experience with sub-bituminous coal as the fuel, where dynamic changes in variables were performed to observe the effects on the unit itself. Measurements included temperature, pressure, and gas concentrations from the reducer and combustor. Furthermore, effects of different variables, such as flue gas recycle ratios (enhancer gas flow rates), feed port injection, and temperature, were observed. Tests confirmed high coal conversions with high purity of CO2 achieved in the flue gas. Overall, the moving bed design of the reducer results in nearly full coal conversion

  7. Investigation of the performance of a copper based oxygen carrier for chemical looping combustion in a 120 kW pilot plant for gaseous fuels

    International Nuclear Information System (INIS)

    Highlights: • A Cu based oxygen carrier for chemical looping combustion has been tested. • A 120 kW pilot plant designed as dual circulating fluidized bed has been used. • Solids inventory and circulation have been identified as critical for performance. • The results are compared with other pilot plants using the same oxygen carrier. • Recommendations for improved reactor designs have been made based on the results. - Abstract: A copper based oxygen carrier prepared by impregnation on a highly porous alumina support (14.2 wt% active CuO) has been tested in a 120 kW chemical looping pilot plant. This oxygen carrier has already been under investigation in other pilot plants up to 10 kW fuel power and showed very good performance, i.e. full fuel conversion was achieved. During the experiments, natural gas has been used as fuel and variations of several process parameters like temperature, fuel power, solids inventory and solids circulation rate have been performed. The copper particles showed good performance regarding conversion of CO and H2 (almost full conversion) but only moderate conversion of CH4 (up to 80%) was achieved. The three process parameters fuel reactor temperature, solids circulation between air and fuel reactor and solids inventory have been identified as significant parameters for fuel conversion, i.e. increasing one of these parameters improves fuel conversion. Continuous analysis of the oxygen carrier particles revealed an initial decay of active CuO content caused by attrition on the external surface of the particles. The CuO content stabilized after 30 h of operation at around 9 wt% and no further decrease was observed

  8. Experimental Investigation of CaMnO3−δ Based Oxygen Carriers Used in Continuous Chemical-Looping Combustion

    Directory of Open Access Journals (Sweden)

    Peter Hallberg

    2014-01-01

    Full Text Available Three materials of perovskite structure, CaMn1−xMxO3−δ (M = Mg or Mg and Ti, have been examined as oxygen carriers in continuous operation of chemical-looping combustion (CLC in a circulating fluidized bed system with the designed fuel power 300 W. Natural gas was used as fuel. All three materials were capable of completely converting the fuel to carbon dioxide and water at 900°C. All materials also showed the ability to release gas phase oxygen when fluidized by inert gas at elevated temperature (700–950°C; that is, they were suitable for chemical looping with oxygen uncoupling (CLOU. Both fuel conversion and oxygen release improved with temperature. All three materials also showed good mechanical integrity, as the fraction of fines collected during experiments was small. These results indicate that the materials are promising oxygen carriers for chemical-looping combustion.

  9. Experiments on biomass gasification using chemical looping with nickel-based oxygen carrier in a 25 kWth reactor

    International Nuclear Information System (INIS)

    Biomass gasification using chemical looping (BGCL) is an innovative biomass gasification technology, which utilizes lattice oxygen from oxygen carrier instead of molecular oxygen from air. This work attempted to investigate the BGCL performance with nickel-based oxygen carrier in a 25 kWth reactor. The new prototype is composed of a high velocity fluidized bed as an air reactor, a cyclone, a bubbling fluidized bed as a fuel reactor, and a loop-seal. At first, the major reactions in the process were presented and chemical reaction thermodynamics in the fuel reactor was analyzed. The NiO/Al2O3 oxygen carrier was then applied in the reactor. Different variables, such as gasification temperature, steam-to-biomass (S/B) ratio and NiO content, were analyzed. The carbon conversion efficiency increased smoothly within the temperature range of 650–850 °C, while the syngas yield reached the maximum of 0.33 Nm3kg−1 at 750 °C. Additionally, based on the tradeoff between carbon conversion efficiency and syngas yield, it was concluded that 30 wt.% was the optimal NiO content. Besides, in order to get high quality syngas with low CO2 emission, CaO-decorated NiO/Al2O3 oxygen carrier was investigated. Experimental results showed that the addition of CaO enhanced the biomass gasification process and increased the syngas yield. - Highlights: • A new 25 kWth prototype was made in this study. • NiO was selected as oxygen carrier in the new prototype. • Gasification temperature, steam-to-biomass ratio and NiO content were investigated. • CaO-decorated NiO/Al2O3 was tested to produce high quality syngas

  10. Operation of fixed-bed chemical looping combustion

    NARCIS (Netherlands)

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

    2013-01-01

    Chemical Looping Combustion is an alternative technology for CO2 capture. While most systems utilize dual circulating fluidized-beds, this work shows that fixed-bed Chemical Looping Combustion is a feasible configuration for this technology. The inherent separation of the CO2 from the depleted air s

  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. 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.

  13. Progress of energy system with chemical-looping combustion

    Institute of Scientific and Technical Information of China (English)

    JIN HongGuang; HONG Hui; HAN Tao

    2009-01-01

    Chemical-looping combustion with zero energy penalty of CO2 separation is a significant breakthrough in resolving energy and environment problems for power generation systems. This paper summarizes the research on energy systems with chemical-looping combustion conducted in recent years, discloses the underlying mechanism of energy release of chemical-looping combustion, describes the trends of the key technology development, and presents the proposed chemicaMooping combustion thermal cycles. This paper may provide a new direction to the synthesis of the next-generation energy system compatible with environment.

  14. 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.

  15. Chemical Looping Pilot Plant Results Using a Nickel-Based Oxygen Carrier; Resultats de l'experimentation sur un pilote operant en boucle chimique avec un materiau transporteur d'oxygene a base de nickel

    Energy Technology Data Exchange (ETDEWEB)

    Proll, T.; Kolbitsch, P.; Bolhar-Nordenkampf, J.; Hofbauer, H. [Vienna University of Technology, Institute of Chemical Engineering, Getreidemarkt 9/166, Vienna 1060 (Austria)

    2011-03-15

    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% (CH{sub 4} conversion) and 92% (CO{sub 2} 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.% CH{sub 4}) 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 CO{sub 2}-ready coupled production of H{sub 2} and N{sub 2} can be interesting pathways for immediate scale-up of the technology. (authors)

  16. Physics-Based Loop Surface Modeling

    Institute of Scientific and Technical Information of China (English)

    秦开怀; 常正义; 王华维; 李登高

    2002-01-01

    Strongly inspired by the research on physics-based dynamic models for sur-faces, we propose a new method for precisely evaluating the dynamic parameters (mass, damp-ing and stiffness matrices, and dynamic forces) for Loop surfaces without recursive subdivisionregardless of regular or irregular faces. It is shown that the thin-plate-energy of Loop surfacescan be evaluated precisely and efficiently, even though there are extraordinary points in theinitial meshes, unlike the previous dynamic Loop surface scheme. Hence, the new methodpresented for Loop surfaces is much more efficient than the previous schemes.

  17. 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

  18. 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, foc

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

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    particles concentration in the upper section of the reactors, thus the gas solids contact. They are interconnected by means of two pneumatically controlled divided loop-seals and a bottom extraction/lift. The system is designed to be as compact as possible, to help up-scaling and enclosure into a pressurized vessel, aiming pressurization in a second phase. In addition several industrial solutions have been utilized, from highly loaded cyclones to several levels of secondary air injections.The divided loop-seals are capable to internally re-circulate part of the entrained solids, uncoupling the solids entrainment from the solids exchange. This will provide a better control on the process increasing its flexibility and helping to fulfil downstream requirements. No mechanical valves are utilized, but gas injections. The bottom extraction compensates the lower entrainment of the FR which has less fluidising gas availability and smaller cross section than the AR. The lift allows adjusting the reactors bottom inventories, thus the pressures in the bottom sections of the reactors. In this way the divided loop-seals are not exposed to large pressure unbalances and the whole system is hydrodynamically more robust. The proposed design was finally validated by means of a full scale cold flow model (CFM), without chemical reactions. A thorough evaluation of the scaling state-of-the-art in fluidization engineering has been done; two are the approaches. One consists of building a small scale model which resembles the hydrodynamics of the bigger hot setup, by keeping constant a set of dimensionless numbers. The other is based on the construction of a full scale model, being careful to be in the same fluidization regime and to utilize particles with the same fluidization properties as the hot setup. In this way the surface to volume ratio is kept the same as that one of the hot rig. The idea presented in this work combines those two strategies, building a full scale CFM. In this way, it

  20. Scale-up of fixed-bed chemical looping combustion

    NARCIS (Netherlands)

    Kimball, E.; Geerdink, P.; Goetheer, E.L.V.

    2011-01-01

    Fixed-bed chemical looping combustion is currently being studied experimentally with the optimization of systems up to 1 kW. One of the key advantages for using the fixed-bed configuration over fluidized-beds is the flexibility in operating parameters that allows for application of CLC not only to p

  1. 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).

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

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    particles concentration in the upper section of the reactors, thus the gas solids contact. They are interconnected by means of two pneumatically controlled divided loop-seals and a bottom extraction/lift. The system is designed to be as compact as possible, to help up-scaling and enclosure into a pressurized vessel, aiming pressurization in a second phase. In addition several industrial solutions have been utilized, from highly loaded cyclones to several levels of secondary air injections.The divided loop-seals are capable to internally re-circulate part of the entrained solids, uncoupling the solids entrainment from the solids exchange. This will provide a better control on the process increasing its flexibility and helping to fulfil downstream requirements. No mechanical valves are utilized, but gas injections. The bottom extraction compensates the lower entrainment of the FR which has less fluidising gas availability and smaller cross section than the AR. The lift allows adjusting the reactors bottom inventories, thus the pressures in the bottom sections of the reactors. In this way the divided loop-seals are not exposed to large pressure unbalances and the whole system is hydrodynamically more robust. The proposed design was finally validated by means of a full scale cold flow model (CFM), without chemical reactions. A thorough evaluation of the scaling state-of-the-art in fluidization engineering has been done; two are the approaches. One consists of building a small scale model which resembles the hydrodynamics of the bigger hot setup, by keeping constant a set of dimensionless numbers. The other is based on the construction of a full scale model, being careful to be in the same fluidization regime and to utilize particles with the same fluidization properties as the hot setup. In this way the surface to volume ratio is kept the same as that one of the hot rig. The idea presented in this work combines those two strategies, building a full scale CFM. In this way, it

  3. Chemical Looping Reactor System Design : Double Loop Circulating Fluidized Bed (DLCFB)

    OpenAIRE

    Bischi, Aldo

    2012-01-01

    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 ...

  4. Materials for Chemical-Looping with Oxygen Uncoupling

    OpenAIRE

    Tobias Mattisson

    2013-01-01

    Chemical-looping with oxygen uncoupling (CLOU) is a novel combustion technology with inherent separation of carbon dioxide. The process is a three-step process which utilizes a circulating oxygen carrier to transfer oxygen from the combustion air to the fuel. The process utilizes two interconnected fluidized bed reactors, an air reactor and a fuel reactor. In the fuel reactor, the metal oxide decomposes with the release of gas phase oxygen (step 1), which reacts directly with the fuel through...

  5. Chemical looping combustion of coal in interconnected fluidized beds

    Institute of Scientific and Technical Information of China (English)

    SHEN LaiHong; ZHENG Min; XIAO Jun; ZHANG Hui; XIAO Rui

    2007-01-01

    Chemical looping combustion is the indirect combustion by use of oxygen carrier.It can be used for CO2 capture in power generating processes. In this paper,chemical looping combustion of coal in interconnected fluidized beds with inherent separation of CO2 is proposed. It consists of a high velocity fluidized bed as an air reactor in which oxygen carrier is oxidized, a cyclone, and a bubbling fluidized bed as a fuel reactor in which oxygen carrier is reduced by direct and indirect reactions with coal. The air reactor is connected to the fuel reactor through the cyclone. To raise the high carbon conversion efficiency and separate oxygen carrier particle from ash, coal slurry instead of coal particle is introduced into the bottom of the bubbling fluidized bed. Coal gasification and the reduction of oxygen carrier with the water gas take place simultaneously in the fuel reactor. The flue gas from the fuel reactor is CO2 and water. Almost pure CO2 could be obtained after the condensation of water. The reduced oxygen carrier is then returned back to the air reactor, where it is oxidized with air. Thermodyanmics analysis indicates that NiO/Ni oxygen carrier is the optimal one for chemical looping combustion of coal.Simulation of the processes for chemical looping combustion of coal, including coal gasification and reduction of oxygen carrier, is carried out with Aspen Plus software. The effects of air reactor temperature, fuel reactor temperature, and ratio of water to coal on the composition of fuel gas, recirculation of oxygen carrier particles, etc., are discussed. Some useful results are achieved. The suitable temperature of air reactor should be between 1050-1150Cand the optimal temperature of the fuel reactor be between 900-950℃.

  6. Chemical looping combustion of coal in interconnected fluidized beds

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chemical looping combustion is the indirect combustion by use of oxygen carrier. It can be used for CO2 capture in power generating processes. In this paper, chemical looping combustion of coal in interconnected fluidized beds with inherent separation of CO2 is proposed. It consists of a high velocity fluidized bed as an air reactor in which oxygen carrier is oxidized, a cyclone, and a bubbling fluidized bed as a fuel reactor in which oxygen carrier is reduced by direct and indirect reactions with coal. The air reactor is connected to the fuel reactor through the cyclone. To raise the high carbon conversion efficiency and separate oxygen carrier particle from ash, coal slurry instead of coal particle is introduced into the bottom of the bubbling fluidized bed. Coal gasification and the reduction of oxygen carrier with the water gas take place simultaneously in the fuel reactor. The flue gas from the fuel reactor is CO2 and water. Almost pure CO2 could be obtained after the con- densation of water. The reduced oxygen carrier is then returned back to the air reactor, where it is oxidized with air. Thermodyanmics analysis indicates that NiO/Ni oxygen carrier is the optimal one for chemical looping combustion of coal. Simulation of the processes for chemical looping combustion of coal, including coal gasification and reduction of oxygen carrier, is carried out with Aspen Plus software. The effects of air reactor temperature, fuel reactor temperature, and ratio of water to coal on the composition of fuel gas, recirculation of oxygen carrier par- ticles, etc., are discussed. Some useful results are achieved. The suitable tem- perature of air reactor should be between 1050―1150℃and the optimal temperature of the fuel reactor be between 900―950℃.

  7. 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

  8. 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.

  9. The chemical decontamination of the Callisto PWR loop

    International Nuclear Information System (INIS)

    The CALLISTO (Capability for Light water Irradiation in Steady state and Transient Operation) is a PWR experimental facility for scientific in-pile studies installed into the BR2 Material Test Reactor. Three experimental rigs, called In-Pile Sections (IPS), are installed in three reactor channels. They are connected to a common pressurized loop, which operates with representative PWR water chemistry (typically 400 ppm boron, 3,5 ppm lithium and 30 ccSTP/kg dissolved hydrogen). The IPSs can be provided with adequate instrumentation and be modified to perform valid irradiation studies in a high neutron flux and in a relevant thermos-hydraulic environment. During more than 15 years of operation, activation products have accumulated into the loop leading to a continuous increase of the dose rates at the work area. Consequently periodic maintenance and inspection operations have become more and more expensive in terms of collective dose uptake. In consultation with the internal and external safety authorities the decision has been made to proceed to the chemical closed-loop decontamination of the most important components of CALLISTO (heater, pressurizer, main and bleed flow coolers). The objective of reducing the dose rates without compromising the integrity of the operational loop has led to the combined use of known soft chemical decontamination products as KMnO4 and H2C2O4. About 10 GBq of Co-60 activity and 250 g of corrosion products were removed from the stainless steel CALLISTO loop. The systems involved had a total volume of 0,5 m3 and a surface area of 18 m2. All released activity and corrosion products were removed by ion exchange resins, leading to the generation of 2x150 liters of radioactive waste. The dose rate reduction factors in contact with the treated components varied between 2 and 12. The collective dose uptake of the entire operation (preparation - decontamination - clean-up) was about 5,5 man.mSv, and thereby in line with the ALARA estimations

  10. Combined chemical looping for energy storage and conversion

    Science.gov (United States)

    Galvita, Vladimir V.; Poelman, Hilde; Marin, Guy B.

    2015-07-01

    Combined chemical looping was demonstrated as novel concept of energy storage in a laboratory scale test. The proposed technology is able to store and release energy from redox chemical looping reactions combined with calcium looping. This process uses Fe3O4 and CaO, two low cost and environmentally friendly materials, while CH4 + CO2 serve as feed. During the reduction of Fe3O4 by CH4, both formation of carbon and metallic iron occur. CO2 acts as mediation gas to facilitate the metal/metal oxide redox reaction and carbon gasification into CO. CaO, on the other hand, is used for storage of CO2. Upon temperature rise, CaCO3 releases CO2, which re-oxidizes the carbon deposits and reduced Fe, thus producing carbon monoxide. The amount of produced CO is higher than the theoretical amount for Fe3O4, because carbon deposits from CH4 equally contribute to the CO yield. After each redox cycle, the material is regenerated, so that it can be used repeatedly, providing a stable process.

  11. Model-based evaluation of a chemical looping combustion plant for energy generation at a pre-commercial scale of 100 MWth

    International Nuclear Information System (INIS)

    Highlights: • Scale-up considerations for a CLC reactor system are presented. • Reactor-level model was used to describe the operation of the reactor system. • Integration of the reactor system and steam turbine cycle was studied. • Plant-level model was used to evaluate the viability of CLC-integrated steam cycle. - Abstract: Chemical looping combustion (CLC) is an emerging combustion technology with an inherent separation of the greenhouse gas CO2. The feasibility of CLC has been proven in various small-scale units worldwide, but the large-scale realization of theoretical or small-scale units is still lacking due to many technical challenges. Most of the existing CLC installations use a configuration of two interacting fluidized bed reactors, and even though the fluidized bed technology is mature and well-established, a high level of uncertainty is included in the attempts to up-scale the reactor system involved in CLC. For progressive scale-up of the new technology, a preliminary design of a 100 MWth pre-commercial CLC unit for gaseous fuels is presented. A reactor-level model was used to predict the performance of such a system, and as a result, the operation of the system was characterized and valuable information of the parameters affecting the process was received. For cost-effective energy generation with efficient CO2 capture, the power plant-level integration of CLC must be conducted carefully, and different plant configurations need to be investigated to find the most optimal solution. Hence, the integration of the reactor system and steam turbine cycle for power production was studied resulting in a suggested plant layout including a CLC boiler system, a simple heat recovery setup, and an integrated steam cycle with a three pressure level steam turbine. A plant-level model was used to evaluate the viability of the plant, and without the purification and compression of CO2, the net cycle efficiency of 42.8% was obtained. It was also found that a

  12. 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

  13. 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.

  14. Fuel reactor modelling in chemical-looping combustion of coal: 1. model formulation

    OpenAIRE

    Abad Secades, Alberto; Gayán Sanz, Pilar; Diego Poza, Luis F. de; García Labiano, Francisco; Adánez Elorza, Juan

    2013-01-01

    A fundamental part of the reliability of the Chemical-Looping Combution system when a 13 solid fuel, such as coal, is fed to the reactor is based on the behaviour of the fuel reactor, which determines the conversion of the solid fuel. The objective of this work is to develop a model describing the fuel reactor in the Chemical–Looping Combustion with coal (CLCC) process. The model is used to simulate the performance of the 1 MWth CLCC rig built in the Technology University of Darmsta...

  15. Phase transition of strongly interacting matter with a chemical potential dependent Polyakov loop potential

    Science.gov (United States)

    Shao, Guo-yun; Tang, Zhan-duo; Di Toro, Massimo; Colonna, Maria; Gao, Xue-yan; Gao, Ning

    2016-07-01

    We construct a hadron-quark two-phase model based on the Walecka-quantum hadrodynamics and the improved Polyakov-Nambu-Jona-Lasinio (PNJL) model with an explicit chemical potential dependence of Polyakov loop potential (μ PNJL model). With respect to the original PNJL model, the confined-deconfined phase transition is largely affected at low temperature and large chemical potential. Using the two-phase model, we investigate the equilibrium transition between hadronic and quark matter at finite chemical potentials and temperatures. The numerical results show that the transition boundaries from nuclear to quark matter move towards smaller chemical potential (lower density) when the μ -dependent Polyakov loop potential is taken. In particular, for charge asymmetric matter, we compute the local asymmetry of u , d quarks in the hadron-quark coexisting phase, and analyze the isospin-relevant observables possibly measurable in heavy-ion collision (HIC) experiments. In general new HIC data on the location and properties of the mixed phase would bring relevant information on the expected chemical potential dependence of the Polyakov loop contribution.

  16. Design and operation of a 1 MWth chemical looping plant

    International Nuclear Information System (INIS)

    Highlights: • First chemical looping combustion tests worldwide in 1 MWth scale were performed in a pilot plant in Darmstadt. • The oxygen demand required for oxidizing unconverted gases is in line with previous experiments at smaller scale. • A system for oxygen injection to fully oxidize unconverted gases in the flue gas duct proved to work successfully. - Abstract: Chemical looping combustion (CLC) is an efficient combustion technology with inherent separation of CO2. A metal oxide is used to transport oxygen from air to the fuel, thus avoiding direct contact between fuel and air. The CLC process imposes a very low energy penalty and low CO2 capture costs. The largest CLC pilot plant worldwide with a nominal power of 1 MWth has been erected at Technische Universität Darmstadt. This paper presents the layout of the 1 MWth pilot plant and first operational results using ilmenite and hard coal as fuel. The fuel reactor was fluidized with a mixture of air and steam, so that partial CLC operation was achieved. Conversion of coal was gradually shifted from combustion to gasification by decreasing the air ratio from 1 to 0.55 in the fuel reactor, leading to production of unconverted gases at the fuel reactor exit. The oxygen demand required for fully oxidizing the unconverted gases varied between 12 and 17. Relating the unconverted gases to the remaining 45% of the fuel that have not been oxidized by air, the oxygen demand would be in the range of 26–38%. A system for oxygen injection to fully convert the unconverted gases in the flue gas duct was proven to work successfully

  17. Chemical looping combustion: A new low-dioxin energy conversion technology.

    Science.gov (United States)

    Hua, Xiuning; Wang, Wei

    2015-06-01

    Dioxin production is a worldwide concern because of its persistence and carcinogenic, teratogenic, and mutagenic effects. The pyrolysis-chemical looping combustion process of disposing solid waste is an alternative to traditional solid waste incineration developed to reduce the dioxin production. Based on the equilibrium composition of the Deacon reaction, pyrolysis gas oxidized by seven common oxygen carriers, namely, CuO, NiO, CaSO4, CoO, Fe2O3, Mn3O4, and FeTiO3, is studied and compared with the pyrolysis gas directly combusted by air. The result shows that the activity of the Deacon reaction for oxygen carriers is lower than that for air. For four typical oxygen carriers (CuO, NiO, Fe2O3, and FeTiO3), the influences of temperature, pressure, gas composition, and tar on the Deacon reaction are discussed in detail. According to these simulation results, the dioxin production in China, Europe, the United States, and Japan is predicted for solid waste disposal by the pyrolysis-chemical looping combustion process. Thermodynamic analysis results in this paper show that chemical looping combustion can reduce dioxin production in the disposal of solid waste. PMID:26040740

  18. Chemical looping combustion: A new low-dioxin energy conversion technology.

    Science.gov (United States)

    Hua, Xiuning; Wang, Wei

    2015-06-01

    Dioxin production is a worldwide concern because of its persistence and carcinogenic, teratogenic, and mutagenic effects. The pyrolysis-chemical looping combustion process of disposing solid waste is an alternative to traditional solid waste incineration developed to reduce the dioxin production. Based on the equilibrium composition of the Deacon reaction, pyrolysis gas oxidized by seven common oxygen carriers, namely, CuO, NiO, CaSO4, CoO, Fe2O3, Mn3O4, and FeTiO3, is studied and compared with the pyrolysis gas directly combusted by air. The result shows that the activity of the Deacon reaction for oxygen carriers is lower than that for air. For four typical oxygen carriers (CuO, NiO, Fe2O3, and FeTiO3), the influences of temperature, pressure, gas composition, and tar on the Deacon reaction are discussed in detail. According to these simulation results, the dioxin production in China, Europe, the United States, and Japan is predicted for solid waste disposal by the pyrolysis-chemical looping combustion process. Thermodynamic analysis results in this paper show that chemical looping combustion can reduce dioxin production in the disposal of solid waste.

  19. 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.

  20. 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. PMID:18497114

  1. 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.

  2. Phase transition of strongly interacting matter with a chemical potential dependent Polyakov loop potential

    CERN Document Server

    Shao, Guo-yun; Di Toro, Massimo; Colonna, Maria; Gao, Xue-yan; Gao, Ning

    2016-01-01

    We construct a hadron-quark two-phase model based on the Walecka-quantum hadrodynamics and the improved Polyakov-Nambu--Jona-Lasinio model with an explicit chemical potential dependence of Polyakov-loop potential ($\\mu$PNJL model). With respect to the original PNJL model, the confined-deconfined phase transition is largely affected at low temperature and large chemical potential. Using the two-phase model, we investigate the equilibrium transition between hadronic and quark matter at finite chemical potentials and temperatures. The numerical results show that the transition boundaries from nuclear to quark matter move towards smaller chemical potential (lower density) when the $\\mu$-dependent Polyakov loop potential is taken. In particular, for charge asymmetric matter, we compute the local asymmetry of $u, d$ quarks in the hadron-quark coexisting phase, and analyse the isospin-relevant observables possibly measurable in heavy-ion collision (HIC) experiments. In general new HIC data on the location and proper...

  3. CFD simulation of a chemical-looping fuel reactor utilizing solid fuel

    Energy Technology Data Exchange (ETDEWEB)

    Mahalatkar, K.; Kuhlman, J.; Huckaby, E.D.; O' Brien, T. [West Virginia University, Morgantown, WV (United States)

    2011-08-15

    A computational fluid dynamic (CFD) study has been carried out for the fuel reactor for a new type of combustion technology called chemical-looping combustion (CLC). CLC involves combustion of fuels by heterogeneous chemical reactions with an oxygen carrier, usually a granular metal oxide, exchanged between two reactors. There have been extensive experimental studies on CLC, however CFD simulations of this concept are quite limited. In the present paper we have developed a CFD model for the fuel reactor of a chemical-looping combustor described in the literature, which utilized a Fe-based carrier (ilmenite) and coal. An Eulerian multiphase continuum model was used to describe both the gas and solid phases, with detailed sub-models to account for fluid-particle and particle-particle interaction forces. Global reaction models of fuel and carrier chemistry were utilized. The transient results obtained from the simulations were compared with detailed experimental time-varying outlet species concentrations (Leion et al., 2008) and provided a reasonable match with the reported experimental data.

  4. 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.

  5. 基于化学链制氧的 O2/CO2燃烧电站性能分析%Performance analysis of an O2/CO2 power plant based on chemical looping air separation

    Institute of Scientific and Technical Information of China (English)

    顾鹏飞; 向文国

    2015-01-01

    采用 Aspen Plus 软件对基于化学链高温空分制氧技术(CLAS)的 O2/CO2燃烧电厂全过程进行建模,对化学链高温空分单元进行运行参数及功耗分析,并对化学链高温空分单元、锅炉热力发电系统和烟气冷却压缩单元(CCU)进行耦合并优化,确定高温烟气抽取温度及抽取流量.结果表明,O2/CO2燃烧系统的净效率为39.2%,仅比不能进行碳捕集的常规电厂低3.54%.然而,基于深冷空分技术的 O2/CO2燃烧系统会使得全厂净效率下降8%~10%.当采取优化措施后,O2/CO2燃烧系统效率能够提高1.65%.烟气冷却压缩单元能耗占总能耗的59.7%,泵能耗占27.1%.化学链制氧单元的供氧浓度为12.2%.%The process of an O2 /CO2 power plant based on chemical looping air separation (CLAS)is modeled using the Aspen Plus software.The operating parameters and power consumption of the CLAS unit are analyzed.The CLAS system,thermal power generation system and flue gas cooling and compression unit (CCU)are coupled and optimized,and the temperature and flow of the flue gas extraction are determined.The results indicate that the net plant efficiency of CLAS O2 /CO2 power plant is 39.2%,which is only 3.54%lower than that of the conventional power plants without carbon capture.However,the O2 /CO2 power plant based on cryogenic air separation technology brings 8% to 10%decrease in the net plant efficiency.By optimizations,the net plant efficiency increases by 1.65%.The energy consumption of the CCU accounts for 59.7% and the pump accounts for 27.1%.The oxygen concentration from the chemical looping air separation unit is 12.2%.

  6. 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.

  7. 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

  8. Adaptive feed-forward loop connection based on error signal

    Science.gov (United States)

    Hidaka, Koichi

    2005-12-01

    In this paper, we investigate effect of changing the connection of feed-forward loop based on error signal. Our motivation of this work is solution to progress of human skill. For the skill model, we study a human simple action such as arm motion. Many models that describe the human arm dynamics have been proposed in recent year. While one type does not need an inverse model of human dynamics, the system based on the model does not include feed-forward loop. On the other hand, another type model has a feed-forward loop and feedback loop systems. This type assumes feed-forward element includes an internal model by repeating action or training and this loop progress our skill. Then we usually have to exercise to get a good performance. This says that we design the internal motion model by training and we move on prediction for motion. Under the assumption, Kawato model is well known. The model proposed that learning of feed-forward element is promoted in brain so that the error of feedback loop decreases. Furthermore, we assume the connections in feedback loop and feed-forward loop are changed. We show numerical simulations and consider that the position error given by our vision changes the skill element and we confirm that the position error is the one of the estimate function for the improvement in our skill.

  9. Loop Subdivision Surface Based Progressive Interpolation

    Institute of Scientific and Technical Information of China (English)

    Fu-Hua (Frank) Cheng; Feng-Tao Fan; Shu-Hua Lai; Cong-Lin Huang; Jia-Xi Wang; Jun-Hai Yong

    2009-01-01

    A new method for constructing interpolating Loop subdivision surfaces is presented. The new method is an extension of the progressive interpolation technique for B-splines. Given a triangular mesh M, the idea is to iteratively upgrade the vertices of M to generate a new control mesh M such that limit surface of M would interpolate M. It can be shown that the iterative process is convergent for Loop subdivision surfaces. Hence, the method is well-defined. The new method has the advantages of both a local method and a global method, i.e., it can handle meshes of any size and any topology while generating smooth interpolating subdivision surfaces that faithfully resemble the shape of the given meshes. The meshes considered here can be open or closed.

  10. Equilibrium thermodynamic analyses of methanol production via a novel Chemical Looping Carbon Arrestor process

    International Nuclear Information System (INIS)

    Highlights: • A novel Chemical Looping Carbon Arrestor Reforming process has been developed. • Energy efficiency of the process is found to be ∼64–70%. • The process emits only about 0.14 mole of carbon dioxide per mole of methanol. • The process offers an efficient and low-emission option for methanol production. - Abstract: Methanol economy is considered as an alternative to hydrogen economy due to the better handling and storage characteristics of methanol fuel than liquid hydrogen. This paper is concerned about a comprehensive equilibrium thermodynamic analysis carried out on methanol production via an innovative Chemical Looping Carbon Arrestor/Reforming process being developed at the University of Newcastle in order to reduce both energy consumption and carbon emissions. The detailed simulation revealed thermodynamic limitations within the Chemical Looping Carbon Reforming process however on the other hand it also confirmed that the new concept is a low energy requirement and low emission option compared to other methanol production technologies. Specifically, the mass and energy balance study showed that the Chemical Looping Carbon Reforming process typically consumes approximately 0.76–0.77 mole methane, 0.25–0.27 mole carbon dioxide, 0.49–0.50 mole water, and 0.51 mole iron oxide (in a chemical looping manner) per mole of methanol production. Moreover, the energy efficiency of Chemical Looping Carbon Reforming process was found to be ∼64–70% and its emission profile was found as low as 0.14 mole carbon dioxide per mole of methanol, which is about 82–88% less than the conventional methanol production process and well below the emission levels of other emerging methanol production technologies

  11. Loop-mirror-based slot waveguide refractive index sensor

    OpenAIRE

    Jun-long Kou; Fei Xu; Yan-qing Lu

    2012-01-01

    Loop mirror has been widely used in fiber optical devices and systems for it provides a smart way to make use of the fiber birefringence properties and can enhance the sensitivity greatly. On the other hand, slot waveguide is very promising for optical sensing applications because of their peculiar spatial mode profile. In this paper, we propose and analyze a loop-mirror-based slot waveguide (LMSW) sensor which can be routinely fabricated in modern high-volume complementary metal-oxide–semico...

  12. 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

  13. Combined oxides as oxygen-carrier material for chemical-looping with oxygen uncoupling

    International Nuclear Information System (INIS)

    Highlights: • Manganese-based combined oxides are examined for chemical-looping combustion applications. • Promising compositions includes (MnyFe1−y)Ox, (MnySi1−y)Ox and CaMnO3−δ. • Study includes thermodynamic analysis and overview of current experimental experiences. - Abstract: Oxygen-carrier materials for chemical-looping with oxygen uncoupling (CLOU) must be capable of taking up and releasing gas-phase O2 at conditions relevant for generation of heat and power. In principle, the capability of a certain material to do so is determined by its thermodynamic properties. This paper provides an overview of the possibility to design feasible oxygen carrier materials from combined oxides, i.e. oxides with crystal structures that include several different cations. Relevant literature is reviewed and the thermodynamic properties and key characteristics of a few selected combined oxide systems are calculated and compared to experimental data. The general challenges and opportunities of the combined oxide concept are discussed. The focus is on materials with manganese as one of its components and the following families of compounds and solid solutions have been considered: (MnyFe1−y)Ox, (MnySi1−y)Ox, CaMnO3−δ, (NiyMn1−y)Ox, (MnyCu1−y)Ox and (MnyMg1−y)Ox. In addition to showing promise from a thermodynamic point of view, reactivity data from experimental investigations suggests that the rate of O2 release can be high for all systems. Thus these combined oxides could also be very suitable for practical application

  14. 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 ope

  15. Study of dimensional changes during redox cycling of oxygen carrier materials for chemical looping combustion

    NARCIS (Netherlands)

    Fossdal, A.; Darell, O.; Lambert, A.; Schols, E.; Comte, E.; Leenman, R.N.; Blom, R.

    2015-01-01

    Dimensional and phase changes of four candidate oxygen carrier materials for chemical looping combustion are investigated by dilatometry and high-temperature X-ray diffraction during four redox cycles. NiO/Ni2AlO4 does not exhibit significant dimensional changes during cycling, and it is shown that

  16. Timing Jitter Analysis for Clock recovery Circuits Based on an Optoelectronic Phase-Locked Loop (OPLL)

    DEFF Research Database (Denmark)

    Zibar, Darko; Mørk, Jesper; Oxenløwe, Leif Katsuo;

    2005-01-01

    Timing jitter of an OPLL based clock recovery is investigated. We demonstrate how loop gain, input and VCO signal jitter, loop filter bandwidth and a loop time delay influence jitter of the extracted clock signal...

  17. Three-loop HTLpt thermodynamics at finite temperature and isospin chemical potential

    CERN Document Server

    Andersen, Jens O; Mustafa, Munshi G; Strickland, Michael

    2015-01-01

    In a previous paper (JHEP {\\bf 05} (2014) 27), we calculated the three-loop thermodynamic potential of QCD at finite temperature $T$ and quark chemical potentials $\\mu_q$ using the hard-thermal-loop perturbation theory (HTLpt) reorganization of finite temperature and density QCD. The result allows us to study the thermodynamics of QCD at finite temperature and isospin chemical potential $\\mu_I$. We calculate the pressure, energy density, and entropy density, the trace anomaly, and the speed of sound at zero and nonzero $\\mu_I$. The second, fourth, and sixth-order isospin susceptibilities are calculated at zero $\\mu_I$. Our results can be directly compared to lattice QCD without Taylor expansions around $\\mu_q=0$ since QCD has no sign problem at finite isospin chemical potential.

  18. In-situ chemical decontamination of a PWR primary loop large components with the MEDOC process

    International Nuclear Information System (INIS)

    Shutdown in 1987 after 25 years of operation, the BR3-PWR was selected in 1989 as one of the four pilot decommissioning projects by the European Commission, in the framework of its five-year plan of Research and Technological Development on decommissioning of nuclear installations. The dismantling of a PWR type reactor leads to the production of large masses of contaminated metallic pieces, including structural materials, primary piping, tanks and heat exchangers. One of our main objectives is to demonstrate that we can minimise the volume of radioactive waste in an economical way by privileging alternative material routes, such as the clearance of materials after thorough decontamination. Therefore the SCK-CEN has developed its own chemical decontamination process, so-called MEDOC (MEtal Decontamination by Oxidation with Cerium), based on the use of Ce(IV) as strong oxidising species in sulphuric acid, which is continuously regenerated by ozone injection at high temperature. The industrial installation, which was designed and constructed in close collaboration with Framatome-ANP (France), started operation in September 1999. Initially designed to decontaminate stainless steel pieces, the process has been easily upgraded to allow the treatment of carbon steel using simply H2SO4. Up to now, more than 30 tons of contaminated materials, including primary pipes and primary pumps housings, have been treated batch wise with success. 69% of material can be directly cleared after treatment (Activity lower than 0.1 Bq/g in 60Co) 27% will be free released after melting (activity lower than 1 Bq/g) and less than 4% have to undergo an additional physical decontamination step prior to clearance. However, the working of our process is not restricted to batch wise operations. Thanks to minor adaptations on the existing plant, the SCK-CEN has recently performed the closed loop decontamination of the large components of the primary loop, namely the steam generator and the

  19. 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.

  20. 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.

  1. 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

  2. Loop-mirror-based slot waveguide refractive index sensor

    Science.gov (United States)

    Kou, Jun-long; Xu, Fei; Lu, Yan-qing

    2012-12-01

    Loop mirror has been widely used in fiber optical devices and systems for it provides a smart way to make use of the fiber birefringence properties and can enhance the sensitivity greatly. On the other hand, slot waveguide is very promising for optical sensing applications because of their peculiar spatial mode profile. In this paper, we propose and analyze a loop-mirror-based slot waveguide (LMSW) sensor which can be routinely fabricated in modern high-volume complementary metal-oxide-semiconductor (CMOS) process. The finite element method (FEM) simulation results show that the birefringence can be as high as 0.8 which is orders of magnitude than that in conventional birefringent fiber loop mirror. High sensitivity up to 6 × 103 nm/RIU (refractive index unit) is achieved by this scheme.

  3. Loop-mirror-based slot waveguide refractive index sensor

    Directory of Open Access Journals (Sweden)

    Jun-long Kou

    2012-12-01

    Full Text Available Loop mirror has been widely used in fiber optical devices and systems for it provides a smart way to make use of the fiber birefringence properties and can enhance the sensitivity greatly. On the other hand, slot waveguide is very promising for optical sensing applications because of their peculiar spatial mode profile. In this paper, we propose and analyze a loop-mirror-based slot waveguide (LMSW sensor which can be routinely fabricated in modern high-volume complementary metal-oxide–semiconductor (CMOS process. The finite element method (FEM simulation results show that the birefringence can be as high as 0.8 which is orders of magnitude than that in conventional birefringent fiber loop mirror. High sensitivity up to 6 × 103 nm/RIU (refractive index unit is achieved by this scheme.

  4. 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)

  5. Fuel reactor modelling in chemical-looping combustion of coal: 2. simulation and optimization

    OpenAIRE

    García Labiano, Francisco; Diego Poza, Luis F. de; Gayán Sanz, Pilar; Abad Secades, Alberto; Adánez Elorza, Juan

    2013-01-01

    Chemical-Looping Combustion of coal (CLCC) is a promising process to carry out coal combustion with carbon capture. The process should be optimized in order to maximize the carbon capture and the combustion efficiency in the fuel reactor, which will depend on the reactor design and the operational conditions. In this work, a mathematical model of the fuel reactor is used to make predictions about the performance of the CLCC process and simulate the behaviour of the system ...

  6. Comparison of carbon capture IGCC with pre-combustion decarbonisation and with chemical-looping combustion

    International Nuclear Information System (INIS)

    Carbon capture from conventional power cycles is accompanied by a significant loss of efficiency. One process concept with a potential for better performance is chemical-looping combustion (CLC). CLC uses a metal oxide to oxidize the fuel, and the reduced metal is then re-oxidized in a second reactor with air. The combustion products CO2 and water remain unmixed with nitrogen, thereby avoiding the need for energy intensive air separation. In this paper, the performance of various configurations of CLC used in integrated gasification combined cycle power plants (CLC-IGCC) are analyzed and compared to a conventional IGCC design with pre-combustion carbon capture by physical absorption. The analysis is based on process simulation using Aspen Plus and GateCycle. Key design parameters are varied, and the results are interpreted using exergy analysis. The CLC-IGCC offers the advantages of higher plant efficiency and more complete carbon capture. The efficiency is very sensitive to changes in the gas turbine inlet temperature for both the CLC and the conventional IGCC designs. The development of oxygen carrier particles with a high thermal stability is therefore crucial for capitalizing on the potential efficiency advantage of CLC.

  7. Nanocomposite oxygen carriers for chemical-looping combustion of sulfur-contaminated synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Rahul D. Solunke; Goetz Veser [United States Department of Energy, Pittsburgh, PA (United States). National Energy Technology Laboratory

    2009-09-15

    Chemical-looping combustion (CLC) is an emerging technology for clean combustion. We have previously demonstrated that the embedding of metal nanoparticles into a nanostructured ceramic matrix can result in unusually active and sinter-resistant nanocomposite oxygen carrier materials for CLC, which combine the high reactivity of metals with the high-temperature stability of ceramics. In the present study, we investigate the effect of H{sub 2}S in a typical coal-derived syngas on the stability and redox kinetics of Ni- and Cu-based nanostructured oxygen carriers. Both carriers show excellent structural stability and only mildly changed redox kinetics upon exposure to H{sub 2}S, despite a significant degree of sulfide formation. Surprisingly, partial sulfidation of the support results in a strong increase in oxygen carrier capacity in both cases because of the addition of a sulfide-sulfate cycle. Overall, the carriers show great potential for use in CLC of high-sulfur fuels. 21 refs., 13 figs. 1 tab.

  8. Chemical looping combustion in a rotating bed reactor--finding optimal process conditions for prototype reactor.

    Science.gov (United States)

    Håkonsen, Silje Fosse; Blom, Richard

    2011-11-15

    A lab-scale rotating bed reactor for chemical looping combustion has been designed, constructed, and tested using a CuO/Al(2)O(3) oxygen carrier and methane as fuel. Process parameters such as bed rotating frequency, gas flows, and reactor temperature have been varied to find optimal performance of the prototype reactor. Around 90% CH(4) conversion and >90% CO(2) capture efficiency based on converted methane have been obtained. Stable operation has been accomplished over several hours, and also--stable operation can be regained after intentionally running into unstable conditions. Relatively high gas velocities are used to avoid fully reduced oxygen carrier in part of the bed. Potential CO(2) purity obtained is in the range 30 to 65%--mostly due to air slippage from the air sector--which seems to be the major drawback of the prototype reactor design. Considering the prototype nature of the first version of the rotating reactor setup, it is believed that significant improvements can be made to further avoid gas mixing in future modified and up-scaled reactor versions.

  9. Gasification Coupled Chemical Looping Combustion of Coal: A Thermodynamic Process Design Study

    OpenAIRE

    Sonali A. Borkhade; Shriwas, Preksha A.; Ganesh R. Kale

    2013-01-01

    A thermodynamic investigation of gasification coupled chemical looping combustion (CLC) of carbon (coal) is presented in this paper. Both steam and CO2 are used for gasification within the temperature range of 500–1200°C. Chemical equilibrium model was considered for the gasifier and CLC fuel reactor. The trends in product compositions and energy requirements of the gasifier, fuel reactor, and air reactor were determined. Coal (carbon) gasification using 1.5 mol H2O and 1.5 mol CO2 per mole c...

  10. 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

  11. Relative Humidity Sensor Based on Microfiber Loop Resonator

    OpenAIRE

    Yangzi Zheng; Xinyong Dong; Chunliu Zhao; Yi Li; Liyang Shao; Shangzhong Jin

    2013-01-01

    A novel relative humidity (RH) sensor based on a microfiber loop resonator (MLR) is proposed and experimentally demonstrated. As refractive index of the microfiber in the MLR is modified by environmental humidity, resonant wavelength of the MLR changes with RH level. By detecting this wavelength shift, RH measurement is realized with a linear response sensitivity of 1.8 pm/% RH. The obvious advantage of this technique over others is that no coating of humidity-sensitive material is required.

  12. A multiple-pass ring oscillator based dual-loop phase-locked loop

    Energy Technology Data Exchange (ETDEWEB)

    Chen Danfeng; Ren Junyan; Deng Jingjing; Li Wei; Li Ning, E-mail: dfchen@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2009-10-15

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-{mu}m RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of -99 dBc/Hz - 1 MHz offset from a 5.5 GHz carrier.

  13. Modelling of Closed Loop Class E Inverter Based Induction Heater

    Directory of Open Access Journals (Sweden)

    S. Arumugam

    2011-01-01

    Full Text Available This study presents simulation of class E inverter based induction heater system using simulink. DC is converted into high frequency AC using class E inverter. This high frequency AC is used for induction heating. Closed loop systems are modeled and they are simulated using Mat lab Simulink.The results of closed loop systems are presented. The proposed amplifier with two series-parallel resonant load networks will allow sinusoidal output voltage to be achieved by associating with the positive and negative quasi-sinusoidal waveforms. The complementarily activated configuration will provide continuous high-ripple-frequency inputcurrent waveforms; this approach significantly reduces electromagnetic interference and requires very little filtering. With the symmetry of the push-pull Class-E Circuit, there is the additional benefit that the even harmonics are suppressed at the load, and thus there are fewer harmonic distortions.

  14. Mass, energy, and exergy balance analysis of chemical looping with oxygen uncoupling (CLOU) process

    International Nuclear Information System (INIS)

    Highlights: • A CLOU reactor system using a CuO-based OC and coal as fuel is analyzed. • Possible operational regions for the chosen OC are identified. • Different heat balance scenarios are investigated. • The second-law efficiency of the system is evaluated. • Various design aspects and process modelling relationships are discussed. - Abstract: Chemical looping with oxygen uncoupling (CLOU) is a promising concept for efficient combustion of solid fuels with an inherent capture of the greenhouse gas CO2. This paper presents a CLOU process scheme with stoichiometric mass, energy, and exergy balances. A CLOU reactor system using medium volatile bituminous coal as fuel and silica-supported CuO as an oxygen carrier is analyzed. The analysis includes the estimation of various design and operational parameters, thermal considerations, and evaluation of the overall performance. The operation of a reactor system of two interacting circulating fluidized beds (CFBs) is greatly influenced by the hydrodynamics. For the CuO oxygen carrier, the hydrodynamic operating range appeared feasible considering the maximum solid circulation rates in current CFB boilers. Depending upon the reactor temperatures, oxygen carrier inventories of 400–680 kg/MW in the system were found necessary for stoichiometric combustion of the fuel. The temperature difference between the reactors should not exceed 50 °C, as otherwise, problems may arise with the heat balance. Exergetic efficiencies in the range of 63–70% were obtained for different combinations of relevant design parameters. It is evident that the possible operating conditions in the system are closely related to the properties of the chosen oxygen carrier. However, the calculation procedure and design criteria presented here are applicable to any oxygen carrier to be used in the process

  15. 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...... linked by redox couples such as Fe2+/Fe3+ and I-/I-3(-) for photoelectrochemical H-2 production and H2S chemical absorption redox reactions are reported. Using functionalized Si as photoelectrodes, H2S was successfully split into elemental sulfur and H-2 with high stability and selectivity under...... simulated solar light. This new conceptual design will not only provide a possible route for using solar energy to convert H2S into valuable resources, but also sheds light on some challenging photochemical reactions such as CH4 activation and CO2 reduction....

  16. Process simulation and maximization of energy output in chemical-looping combustion using ASPEN plus

    Directory of Open Access Journals (Sweden)

    Xiao Zhang, Subhodeep Banerjee, Ling Zhou, Ramesh Agarwal

    2015-01-01

    Full Text Available Chemical-looping combustion (CLC is currently considered as a leading technology for reducing the economic cost of CO2 capture. In this paper, several process simulations of chemical-looping combustion are conducted using the ASPEN Plus software. The entire CLC process from the beginning of coal gasification to the reduction and oxidation of the oxygen carrier is modeled and validated against experimental data. The energy balance of each major component of the CLC process, e.g., the fuel and air reactors and air/flue gas heat exchangers is examined. Different air flow rates and oxygen carrier feeding rates are used in the simulations to obtain the optimum ratio of coal, air, and oxygen carrier that produces the maximum power. Two scaled-up simulations are also conducted to investigate the influence of increase in coal feeding on power generation. It is demonstrated that the optimum ratio of coal, air supply, and oxygen carrier for maximum power generation remains valid for scaled-up cases with substantially larger coal feeding rates; the maximum power generation scales up linearly by using the process simulation models in ASPEN Plus. The energy output from four different types of coals is compared, and the optimum ratio of coal, air supply and oxygen carrier for maximum power generation for each type of coal is determined.

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

    International Nuclear Information System (INIS)

    Attempting to counteract the consequences of climate change, leading industrial nations have agreed on reducing their CO2 emissions significantly. To reach these reduction goals, it is essential to reduce the CO2 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 CO2. 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 CO2 can be safely captured in a pilot plant of this scale.

  18. Adaptive Simulated Annealing Based Protein Loop Modeling of Neurotoxins

    Institute of Scientific and Technical Information of China (English)

    陈杰; 黄丽娜; 彭志红

    2003-01-01

    A loop modeling method, adaptive simulated annealing, for ab initio prediction of protein loop structures, as an optimization problem of searching the global minimum of a given energy function, is proposed. An interface-friendly toolbox-LoopModeller in Windows and Linux systems, VC++ and OpenGL environments is developed for analysis and visualization. Simulation results of three short-chain neurotoxins modeled by LoopModeller show that the method proposed is fast and efficient.

  19. Effect of Gasifying Medium on the Coal Chemical Looping Gasification with CaSO4 as Oxygen Carrier☆

    Institute of Scientific and Technical Information of China (English)

    Yongzhuo Liu; Weihua Jia; Qingjie Guo; Hojung Ryu

    2014-01-01

    The chemical looping gasification uses an oxygen carrier for solid fuel gasification by supplying insufficient lattice oxygen. The effect of gasifying medium on the coal chemical looping gasification with CaSO4 as oxygen carrier is investigated in this paper. The thermodynamical analysis indicates that the addition of steam and CO2 into the system can reduce the reaction temperature, at which the concentration of syngas reaches its maximum value. Experimental result in thermogravimetric analyzer and a fixed-bed reactor shows that the mixture sample goes through three stages, drying stage, pyrolysis stage and chemical looping gasification stage, with the temper-ature for three different gaseous media. The peak fitting and isoconversional methods are used to determine the reaction mechanism of the complex reactions in the chemical looping gasification process. It demonstrates that the gasifying medium (steam or CO2) boosts the chemical looping process by reducing the activation energy in the overall reaction and gasification reactions of coal char. However, the mechanism using steam as the gasifying medium differs from that using CO2. With steam as the gasifying medium, parallel reactions occur in the begin-ning stage, followed by a limiting stage shifting from a kinetic to a diffusion regime. It is opposite to the reaction mechanism with CO2 as the gasifying medium.

  20. Alstom's Chemical Looping Combustion Prototype for CO{sub 2} Capture from Existing Pulverized Coal-Fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Andrus, Herbert; Chiu, John; Edberg, Carl; Thibeault, Paul; Turek, David

    2012-09-30

    Alstom’s Limestone Chemical Looping (LCL™) process has the potential to capture CO{sub 2} 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 CO{sub 2} 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 plant.

  1. FPGA-Based Implementation of All-Digital QPSK Carrier Recovery Loop Combining Costas Loop and Maximum Likelihood Frequency Estimator

    Directory of Open Access Journals (Sweden)

    Kaiyu Wang

    2014-01-01

    Full Text Available This paper presents an efficient all digital carrier recovery loop (ADCRL for quadrature phase shift keying (QPSK. The ADCRL combines classic closed-loop carrier recovery circuit, all digital Costas loop (ADCOL, with frequency feedward loop, maximum likelihood frequency estimator (MLFE so as to make the best use of the advantages of the two types of carrier recovery loops and obtain a more robust performance in the procedure of carrier recovery. Besides, considering that, for MLFE, the accurate estimation of frequency offset is associated with the linear characteristic of its frequency discriminator (FD, the Coordinate Rotation Digital Computer (CORDIC algorithm is introduced into the FD based on MLFE to unwrap linearly phase difference. The frequency offset contained within the phase difference unwrapped is estimated by the MLFE implemented just using some shifter and multiply-accumulate units to assist the ADCOL to lock quickly and precisely. The joint simulation results of ModelSim and MATLAB show that the performances of the proposed ADCRL in locked-in time and range are superior to those of the ADCOL. On the other hand, a systematic design procedure based on FPGA for the proposed ADCRL is also presented.

  2. 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

  3. Simulation and validation of chemical-looping combustion using ASPEN plus

    Directory of Open Access Journals (Sweden)

    Ling Zhou, Zheming Zhang, Ramesh K. Agarwal

    2014-01-01

    Full Text Available Laboratory-scale experimental studies have demonstrated that Chemical-Looping Combustion (CLC is an advanced technology which holds great potential for high-efficiency low-cost carbon capture. The generated syngas in CLC is subsequently oxidized to CO2 and H2O by reaction with an oxygen carrier. In this paper, process-level models of CLC are established in ASPEN Plus code for detailed simulations. The entire CLC process, from the beginning of coal gasification to reduction and oxidation of the oxygen carrier is modeled. The heat content of each major component such as fuel and air reactors and air/flue gas heat exchangers is carefully examined. Large amount of energy is produced in the fuel reactor, but energy needs to be supplied to the air reactor. The overall performance and efficiency of the modeled CLC systems are also evaluated.

  4. Simulation and validation of chemical-looping combustion using ASPEN plus

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ling [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States); Zhang, Zheming; Agarwal, Ramesh K. [Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States)

    2013-07-01

    Laboratory-scale experimental studies have demonstrated that Chemical-Looping Combustion (CLC) is an advanced technology which holds great potential for high-efficiency low-cost carbon capture. The generated syngas in CLC is subsequently oxidized to CO2 and H2O by reaction with an oxygen carrier. In this paper, process-level models of CLC are established in ASPEN Plus code for detailed simulations. The entire CLC process, from the beginning of coal gasification to reduction and oxidation of the oxygen carrier is modeled. The heat content of each major component such as fuel and air reactors and air/flue gas heat exchangers is carefully examined. Large amount of energy is produced in the fuel reactor, but energy needs to be supplied to the air reactor. The overall performance and efficiency of the modeled CLC systems are also evaluated.

  5. The Physical/Chemical Closed-Loop Life Support Research Project

    Science.gov (United States)

    Bilardo, Vincent J., Jr.

    1990-01-01

    The various elements of the Physical/Chemical Closed-Loop Life Support Research Project (P/C CLLS) are described including both those currently funded and those planned for implementation at ARC and other participating NASA field centers. The plan addresses the entire range of regenerative life support for Space Exploration Initiative mission needs, and focuses initially on achieving technology readiness for the Initial Lunar Outpost by 1995-97. Project elements include water reclamation, air revitalization, solid waste management, thermal and systems control, and systems integration. Current analysis estimates that each occupant of a space habitat will require a total of 32 kg/day of supplies to live and operate comfortably, while an ideal P/C CLLS system capable of 100 percent reclamation of air and water, but excluding recycling of solid wastes or foods, will reduce this requirement to 3.4 kg/day.

  6. Effective Polyakov loop models for QCD-like theories at finite chemical potential

    CERN Document Server

    Scior, Philipp

    2016-01-01

    We study genuine finite density effects in QCD-like theories with three-dimensional Polyakov-loop effective theories for heavy quarks. These are derived from the full QCD-like theories by combined strong-coupling and hopping expansions. In particular, we investigate the cold and dense regimes of phase diagrams where we expect to find Bose-Einstein-condensation of diquark baryons or a fermionic first-order liquid-gas transition, depending on the gauge group of the theory. In two-color QCD, for example, we observe evidence of a continuous zero-temperature transition to finite diquark density when the quark chemical potential $\\mu$ reaches half the diquark mass, i.e. without binding energy. In G$_2$-QCD we observe, in addition to this "Silver Blaze" onset of diquark density, a second transition in the density towards an exponential increase by roughly $3\\mu/T$ corresponding to a finite density of G$_2$-nucleons.

  7. Parallel-cascade-based mechanisms for heating solar coronal loops: test against observations

    CERN Document Server

    Li, Bo; Li, Xing; Xia, Li-Dong

    2014-01-01

    The heating of solar coronal loops is at the center of the problem of coronal heating. Given that the origin of the fast solar wind has been tracked down to atmospheric layers with transition region or even chromospheric temperatures, it is worthy attempting to address whether the mechanisms proposed to provide the basal heating of the solar wind apply to coronal loops as well. We extend the loop studies based on a classical parallel-cascade scenario originally proposed in the solar wind context by considering the effects of loop expansion, and perform a parametric study to directly contrast the computed loop densities and electron temperatures with those measured by TRACE and YOHKOH/SXT. This comparison yields that with the wave amplitudes observationally constrained by SUMER measurements, while the computed loops may account for a significant fraction of SXT loops, they seem too hot when compared with TRACE loops. Lowering the wave amplitudes does not solve this discrepancy, introducing magnetic twist will ...

  8. Energy and exergy analysis of chemical looping combustion technology and comparison with pre-combustion and oxy-fuel combustion technologies for CO2 capture

    OpenAIRE

    Mukherjee, S.; Kumar, P.; Yang, A.; P. Fennell

    2015-01-01

    Abstract Carbon dioxide (CO2) emitted from conventional coal-based power plants is a growing concern for the environment. Chemical looping combustion (CLC), pre-combustion and oxy-fuel combustion are promising CO2 capture technologies which allow clean electricity generation from coal in an integrated gasification combined cycle (IGCC) power plant. This work compares the characteristics of the above three capture technologies to those of a conventional IGCC plant without CO2 capture. CLC tech...

  9. Optimization of H2 production with CO2 capture by steam reforming of methane integrated with a chemical-looping combustion system

    OpenAIRE

    Pans Castillo, Miguel Ángel; Abad Secades, Alberto; Diego Poza, Luis F. de; García Labiano, Francisco; Gayán Sanz, Pilar; Adánez Elorza, Juan

    2013-01-01

    Methane steam reforming (SR) integrated with a chemical-looping combustion (CLC) system is a new process for producing hydrogen from natural gas, allowing carbon dioxide capture with a low energy penalty. In this study, mass and enthalpy balances of an SR-CLC system were carried out to determine the autothermal operating conditions for optimal H2 production. The evaluation was conducted using iron-based oxygen carriers. Two configurations were analysed, firstly with the reformer tubes inside ...

  10. 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.

  11. Self-oscillating loop based piezoelectric power converter

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to a piezoelectric power converter comprising an input driver electrically coupled directly to an input or primary electrode of the piezoelectric transformer without any intervening series or parallel inductor. A feedback loop is operatively coupled between an output...... voltage of the piezoelectric transformer and the input driver to provide a self-oscillation loop around a primary section of the piezoelectric transformer oscillating at an excitation frequency. Electrical characteristics of the feedback loop are configured to set the excitation frequency of the self......- oscillation loop within a zero-voltage-switching (ZVS) operation range of the piezoelectric transformer....

  12. A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion Impact du modèle de réaction sur les simulations CFD de la combustion en boucle chimique

    Directory of Open Access Journals (Sweden)

    Kruggel-Emden H.

    2011-03-01

    Full Text Available Chemical Looping Combustion is an energy efficient combustion technology for the inherent separation of carbon dioxide for both gaseous and solid fuels. For scale up and further development of this process multi-phase CFD-based simulations have a strong potential which rely on kinetic models for the solid/gaseous reactions. Reaction models are usually simple in structure in order to keep the computational cost low. They are commonly derived from thermogravimetric experiments. With only few CFD-based simulations performed on chemical looping combustion, there is a lack in understanding of the role and of the sensitivity of the applied chemical reaction model on the outcome of a simulation. The aim of this investigation is therefore the study of three different carrier materials CaSO4, Mn3O4 and NiO with the gaseous fuels H2 and CH4 in a batch type reaction vessel. Four reaction models namely the linear shrinking core, the spherical shrinking core, the Avrami-Erofeev and a recently proposed multi parameter model are applied and compared on a case by case basis. La combustion en boucle chimique (Chemical Looping Combustion est une technologie de combustion efficace permettant le captage in situ du CO2 pour des charges gazeuses ou solides. Dans l’optique du développement et de l’extrapolation du procédé, la CFD est un outil de simulation à fort potentiel qui s’appuie notamment sur des modèles cinétiques pour décrire les réactions gaz-solide. Ces modèles décrivant les réactions sont généralement assez simples pour limiter les temps de simulation et sont obtenus à partir d’expérimentations en thermobalance. Il y a encore peu de travaux de modélisation CFD du procédé CLC et il est difficile d’estimer l’importance du modèle décrivant les réactions chimiques sur les résultats des simulations. Le but de ce travail est donc d’étudier la combustion de charges gazeuses H2 et CH4 dans des réacteurs en batch en consid

  13. A Simple Model for the Interference Between Event-Based Control Loops Using a Shared Medium

    OpenAIRE

    Henningsson, Toivo; Cervin, Anton

    2010-01-01

    Traditionally, control loops are closed using periodic sensing and actuation. When communication resources are scarce, however, much may be gained from transmitting only when something important has happened in the loop. This paper presents a simple model of the interference between event-based control loops caused by sharing a common medium, based on the coupled dynamics of a Markov chain representing the state of the medium, and the processes modeled as integrators disturbed by white noise....

  14. 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.

  15. 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.

  16. Chemical looping coal gasification with calcium ferrite and barium ferrite via solid--solid reactions

    Energy Technology Data Exchange (ETDEWEB)

    Siriwardane, Ranjani [U.S. Department of Energy/NETL; Riley, Jarrett [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); Tian, Hanjing [West Virginia Univ., Morgantown, WV (United States); Richards, George [U.S. Department of Energy/NETL

    2016-01-01

    Coal gasification to produce synthesis gas by chemical looping was investigated with two oxygen carriers, barium ferrite (BaFe2O4) and calcium ferrite (CaFe2O4). 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 BaFe2O4 and CaFe2O4 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 (H2) and carbon monoxide (CO), but carbon dioxide (CO2) remained low because these oxygen carriers have minimal reactivity with H2 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 H2 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.

  17. COGNITIVE AGENTS BASED SECURITY SCHEME TO HANDLE ROUTING LOOPS IN WIRELESS NETWORKS

    OpenAIRE

    Kumar, R.; G. Kousalya

    2014-01-01

    Routers in wireless networks are often prone to variety of attacks like a man in the middle, distributed denial of service, smurf, ping of death, routing loops, counting to infinity. Among all these attacks routing loop is the most common one and it have a harmful effect on network performance. In this study, we have proposed a novel cognitive agents based security scheme to handle routing loops in wireless networks. The proposed scheme uses Cognitive Agents (CAs) on every routers with Observ...

  18. DESIGN AND MODELLING HILBERT TRANSFORM BASED PHASE DETECTOR FOR ALL DIGITAL PHASE LOCKED LOOP

    OpenAIRE

    Anupama Patil*, Dr P.H.Tandel

    2016-01-01

    The Phase Locked Loop (PLL) is an almost always used electronics circuit for communication systems like modulator, demodulator, frequency generator and frequency synthesizer etc. All-digital phase locked loop (ADPLL) is digital version of the PLL. In this paper, a novel Hilbert transform based phase detection system for all-digital phase locked loop (ADPLL) is presented. The digital discrete time components are used to realize the phase detector system reducing the complexity of the design. T...

  19. 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

  20. Hardware platforms for MEMS gyroscope tuning based on evolutionary computation using open-loop and closed -loop frequency response

    Science.gov (United States)

    Keymeulen, Didier; Ferguson, Michael I.; Fink, Wolfgang; Oks, Boris; Peay, Chris; Terrile, Richard; Cheng, Yen; Kim, Dennis; MacDonald, Eric; Foor, David

    2005-01-01

    We propose a tuning method for MEMS gyroscopes based on evolutionary computation to efficiently increase the sensitivity of MEMS gyroscopes through tuning. The tuning method was tested for the second generation JPL/Boeing Post-resonator MEMS gyroscope using the measurement of the frequency response of the MEMS device in open-loop operation. We also report on the development of a hardware platform for integrated tuning and closed loop operation of MEMS gyroscopes. The control of this device is implemented through a digital design on a Field Programmable Gate Array (FPGA). The hardware platform easily transitions to an embedded solution that allows for the miniaturization of the system to a single chip.

  1. Inner Current Loop Analysis and Design Based on Resonant Regulators for Isolated Microgrids

    DEFF Research Database (Denmark)

    Federico, de Bosio; de Sousa Ribeiro, Luiz Antonio; Soares Lima, Marcel;

    2015-01-01

    Inner current and voltage loops are fundamental in achieving good performance of microgrids based on power electronics voltage source inverters. The analysis and design of these loops are essential for the adequate operation of these systems. This paper investigates the effect of state feedback...

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

    Energy Technology Data Exchange (ETDEWEB)

    Hamers, H.P.; Gallucci, F.; Van Sint Annaland, M. [Multiphase Reactor Group, Chemical Process Intensification, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Cobden, P.D. [Energy Research Centre of the Netherlands (ECN), P.O. Box 1, 1755 ZG Petten (Netherlands); Kimball, E. [TNO Gas Treatment, P.O. Box 6000, 2600 JA Delft (Netherlands)

    2013-08-15

    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 operation. However, high pressure operation allows the use of inherently more efficient power cycles than low pressure fluidized bed solutions. This paper quantifies the challenges in high pressure operation and introduces a novel reactor concept with which those challenges can be addressed. Continuous cyclic operation of a packed bed CLC system is simulated in a 1D numerical reactor model. Importantly, it is demonstrated that the temperature profiles that can occur in a packed bed reactor as a result of the different process steps do not accumulate, and have a negligible effect on the overall performance of the system. Moreover, it has been shown that an even higher energy efficiency can be achieved by feeding the syngas from the opposite direction during the reduction step (i.e. countercurrent operation). Unfortunately, in this configuration mode, more severe temperature fluctuations occur in the reactor exhaust, which is disadvantageous for the operation of a downstream gas turbine. Finally, a novel reactor configuration is introduced in which the desired temperature rise for obtained hot pressured air suitable for a gas turbine is obtained by carrying out the process with two packed bed reactor in series (two-stage CLC). This is shown to be a good alternative to the single bed configuration, and has the added advantage of decreasing the demands on both the oxygen carrier and the reactor materials and design specification.

  3. 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.

  4. Using Low-Cost Iron-Based Materials as Oxygen Carriers for Chemical Looping Combustion Utilisation de matériaux bon marché à base de fer comme transporteur d’oxygène dans la combustion en boucle chimique

    Directory of Open Access Journals (Sweden)

    Jerndal E.

    2011-03-01

    Full Text Available In chemical looping combustion with solid fuels, the oxygen-carrier lifetime is expected to be shorter than with gaseous fuels. Therefore, it is particularly important to use low-cost oxygen carriers in solid fuel applications. Apart from being cheap, these oxygen carriers should be able to convert the CO and H2 produced from the solid fuel gasification and be sufficiently hard to withstand fragmentation. Several low-cost iron-based materials displayed high conversion of syngas and high mechanical strength and can be used for further development of the technology. These materials include oxide scales from Sandvik and Scana and an iron ore from LKAB. All tested oxygen carriers showed higher gas conversion than a reference sample, the mineral ilmenite. Generally, softer oxygen carriers were more porous and appeared to have a higher reactivity towards syngas. When compared with ilmenite, the conversion of CO was higher for all oxygen carriers and the conversion of H2 was higher when tested for longer reduction times. The oxygen carrier Sandvik 2 displayed the highest conversion of syngas and was therefore selected for solid fuel experiments. The conversion rate of solid fuels was higher with Sandvik 2 than with the reference sample, ilmenite. Pour appliquer la combustion en boucle chimique à des charges solides, il est important d’utiliser des matériaux transporteurs d’oxygène bon marché. En effet, la durée de vie du transporteur d’oxygène risque d’être plus courte sur charge solide que sur charge gazeuse. Ces matériaux doivent également bien convertir le monoxyde de carbone et l’hydrogène résultant de la gasification, tout en étant suffisamment durs pour résister à la fragmentation. Plusieurs matériaux ont montré un potentiel de conversion élevé sur le gaz de synthèse ainsi qu’une résistance mécanique élevée, ce qui permet d’envisager leur utilisation lors des développements futurs de la technologie. Parmi ces

  5. Virtual Induction Loops Based on Cooperative Vehicular Communications

    OpenAIRE

    Maria Calderon; Bernardos, Carlos J.; Marco Gramaglia

    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 evaluat...

  6. 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

  7. A LOOP-BASED APPROACH IN CLUSTERING AND ROUTING IN MOBILE AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Li Yanping; Wang Xin; Xue Xiangyang; C.K. Toh

    2006-01-01

    Although clustering is a convenient framework to enable traffic control and service support in Mobile Ad hoc NETworks (MANETs), it is seldom adopted in practice due to the additional traffic overhead it leads to for the resource limited ad hoc network. In order to address this problem, we proposed a loop-based approach to combine clustering and routing. By employing loop topologies, topology information is disseminated with a loop instead of a single node, which provides better robustness, and the nature of a loop that there are two paths between each pair of nodes within a loop suggests smart route recovery strategy. Our approach is composed of setup procedure, regular procedure and recovery procedure to achieve clustering, routing and emergent route recovering.

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

    International Nuclear Information System (INIS)

    CLC (chemical looping combustion) promises to be a more efficient way of CO2 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 CO2 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 CO2 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

  9. Capacitively Loaded Loop-Based Antennas with Reconfigurable Radiation Patterns

    Directory of Open Access Journals (Sweden)

    Saber Dakhli

    2015-01-01

    Full Text Available A class of metamaterial-inspired antennas having reconfigurable radiation patterns is proposed. They consist of a driven monopole antenna with one- and two-capacitively loaded loop (CLL, near field resonant parasitic elements. Two configurations are studied by considering the state of these CLL elements as being either open or closed configurations. Simulation results explain the design features and demonstrate that the structure can change its beam direction simply by controlling the switched states. Two prototypes with one- and two-CLL elements were fabricated and tested. The measured impedance mismatch and radiation pattern results are presented and compared to the corresponding simulated values.

  10. Robust PCA-Based Abnormal Traffic Flow Pattern Isolation and Loop Detector Fault Detection

    Institute of Scientific and Technical Information of China (English)

    JIN Xuexiang; ZHANG Yi; LI Li; HU Jianming

    2008-01-01

    One key function of intelligent transportation systems is to automatically detect abnormal traffic phenomena and to help further investigations of the cause of the abnormality. This paper describes a robust principal components analysis (RPCA)-based abnormal traffic flow pattern isolation and loop detector fault detection method. The results show that RPCA is a useful tool to distinguish regular traffic flow from abnor-mal traffic flow patterns caused by accidents and loop detector faults. This approach gives an effective traffic flow data pre-processing method to reduce the human effort in finding potential loop detector faults. The method can also be used to further investigate the causes of the abnormality.

  11. Analysis of Applicability of ISO 9564 PIN based Authentication to Closed-Loop Mobile Payment Systems

    Directory of Open Access Journals (Sweden)

    Amal Saha

    2014-09-01

    Full Text Available Payment transactions initiated through a mobile device are growing and security concerns must be addressed. People coming from payment card industry often talk passionately about porting ISO 9564 PIN standard based authentication in open-loop card payment to closed-loop mobile financial transactions and certification of closed-loop payment product or solution against this standard. In reality, so far this standard has not been adopted in closed-loop mobile payment authentication and applicability of this ISO standard must be studied carefully before adoption. The authors do a critical analysis of the applicability of this ISO specification and make categorical statement about relevance of compliance to closed-loop mobile payment. Security requirements for authentication in closed-loop mobile payment systems are not standardised through ISO 9564 standard, Common Criteria [3], etc. Since closed-loop mobile payment is a relatively new field, the authors make a case for Common Criteria Recognition Agreement (CCRA or other standards organization to push for publication of a mobile device-agnostic Protection Profile or standard for it, incorporating the suggested authentication approaches.

  12. A closed-loop based framework for design requirement management

    DEFF Research Database (Denmark)

    Zhang, Zhinan; Li, Xuemeng; Liu, Zelin

    2014-01-01

    Requirement management plays a crucial role in determining a successful engineering design project. The focus of current requirement research is on the development of requirement elicitation, analysis and formalization methods and tools. Moreover, the existing requirement research often pays...... attention to the fuzzy front end of product design process. In fact, there exists more needs for requirement knowledge at each stage of a product lifecycle and requirement also has its own lifecycle. However, the research in the field of engineering design lack of a framework to support requirement...... management from product lifecycle, and requirement and requirement management lifecycle views. This paper highlights the importance of requirement lifecycle management and aims at closing the requirement information loop in product lifecycle. Then, it addresses the requirement management in engineering...

  13. One-Loop Renormalization of Non-Abelian Gauge Theory and \\beta Function Based on Loop Regularization Method

    OpenAIRE

    Cui, Jian-Wei; Wu, Yue-Liang(State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Zhong Guan Cun East Street 55 #, P.O. Box 2735, Beijing, 100190 P.R. China)

    2008-01-01

    All one-loop renormalization constants for Non-Abelian gauge theory are computed in details by using the symmetry-preserving Loop Regularization method proposed in\\cite{LR1,LR2}. The resulting renormalization constants are manifestly shown to satisfy Ward-Takahaski-Slavnov-Taylor identities, and lead to the well-known one loop $\\beta$ function for Non-Abelian gauge theory of QCD\\cite{GWP}. The loop regularization method is realized in the dimension of original field theories, it maintains not...

  14. Wiener's Loop Filter for PLL-Based Carrier Recovery of OQPSK and MSK-Type Modulations

    Directory of Open Access Journals (Sweden)

    Arnaldo Spalvieri

    2008-01-01

    Full Text Available This letter considers carrier recovery for offset quadrature phase shift keying (OQPSK and minimum shift keying-type (MSK-type modulations based on phase-lock loop (PLL. The concern of the letter is the optimization of the loop filter of the PLL. The optimization is worked out in the light of Wiener's theory taking into account the phase noise affecting the incoming carrier, the additive white Gaussian noise that is present on the channel, and the self-noise produced by the phase detector. Delay in the loop, which may affect the numerical implementation of the PLL, is also considered. Closed-form expressions for the loop filter and for the mean-square error are given for the case where the phase noise is characterized as a first-order process.

  15. Digitized self-oscillating loop for piezoelectric transformer-based power converters

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh; Andersen, Thomas; Zhang, Zhe;

    2016-01-01

    A new method is implemented in designing of self-oscillating loop for driving piezoelectric transformers. The implemented method is based on combining both analog and digital control systems. Digitized delay, or digitized phase shift through the self-oscillating loop results in a very precise...... frequency control and ensures an optimum operation of the piezoelectric transformer in terms of voltage gain and efficiency. In this work, additional time delay is implemented digitally for the first time through 16 bit digital-to-analog converter to the self-oscillating loop. Delay control setpoints...... updates at a rate of 417 kHz. This allows the control loop to dynamically follow frequency changes of the transformer in each resonant cycle. The operation principle behind self-oscillating is discussed in this paper. Moreover, experimental results are reported....

  16. Improving Loop Modeling of the Antibody Complementarity-Determining Region 3 Using Knowledge-Based Restraints.

    Science.gov (United States)

    Finn, Jessica A; Koehler Leman, Julia; Willis, Jordan R; Cisneros, Alberto; Crowe, James E; Meiler, Jens

    2016-01-01

    Structural restrictions are present even in the most sequence diverse portions of antibodies, the complementary determining region (CDR) loops. Previous studies identified robust rules that define canonical structures for five of the six CDR loops, however the heavy chain CDR 3 (HCDR3) defies standard classification attempts. The HCDR3 loop can be subdivided into two domains referred to as the "torso" and the "head" domains and two major families of canonical torso structures have been identified; the more prevalent "bulged" and less frequent "non-bulged" torsos. In the present study, we found that Rosetta loop modeling of 28 benchmark bulged HCDR3 loops is improved with knowledge-based structural restraints developed from available antibody crystal structures in the PDB. These restraints restrict the sampling space Rosetta searches in the torso domain, limiting the φ and ψ angles of these residues to conformations that have been experimentally observed. The application of these restraints in Rosetta result in more native-like structure sampling and improved score-based differentiation of native-like HCDR3 models, significantly improving our ability to model antibody HCDR3 loops. PMID:27182833

  17. Dissecting the chemical interactions and substrate structural signatures governing RNA polymerase II trigger loop closure by synthetic nucleic acid analogues

    DEFF Research Database (Denmark)

    Xu, Liang; Butler, Kyle Vincent; Chong, Jenny;

    2014-01-01

    The trigger loop (TL) of RNA polymerase II (Pol II) is a conserved structural motif that is crucial for Pol II catalytic activity and transcriptional fidelity. The TL remains in an inactive open conformation when the mismatched substrate is bound. In contrast, TL switches from an inactive open...... state to a closed active state to facilitate nucleotide addition upon the binding of the cognate substrate to the Pol II active site. However, a comprehensive understanding of the specific chemical interactions and substrate structural signatures that are essential to this TL conformational change...... II. This study reveals novel insights into understanding the molecular basis of TL conformational transition upon substrate binding during Pol II transcription. This synthetic chemical biology approach may be extended to understand the mechanisms of other RNA polymerases as well as other nucleic acid...

  18. Solid-Fueled Pressurized Chemical Looping with Flue-Gas Turbine Combined Cycle for Improved Plant Efficiency and CO{sub 2} Capture

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kunlei; Chen, Liangyong; Zhang, Yi; Richburg, Lisa; Simpson, James; White, Jay; Rossi, Gianalfredo

    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.

  19. FPGA-based model of an inverted pendulum hardware-in-the-loop simulations

    OpenAIRE

    Gregorio Moreno, Roberto

    2010-01-01

    An FPGA-Based Model of an Inverted Pendulum for Hardware-in-the-Loop Simulations consists of a specific study of the SCT Pendulum dynamics in order to find a realistic model and its later implementation in FPGA technology. The design flow is based on Matlab Simulink/Xilinx System Generator, final results having proven this hardware model to be a good substitute for the real pendulum, which makes it an ideal tool for testing controllers in Real-Time and Hardware-in-the-Loop Simulations. ------...

  20. Closing the loop: Captured CO2 as a feedstock in the chemical industry

    OpenAIRE

    Otto, Alexander; Grube, Thomas; Schiebahn, Sebastian; Stolten, Detlef

    2015-01-01

    The utilization of ‘captured’ CO2 as a feedstock in the chemical industry for the synthesis of certain chemical products offers an option for preventing several million tons of CO2 emissions each year while increasing independence from fossil fuels. For this reason, interest is increasing in the feasibility of deploying captured CO2 in this manner. Numerous scientific publications describe laboratory experiments in which CO2 has been successfully used as a feedstock for the synthesis of vario...

  1. Model based non-invasive estimation of PV loop from echocardiography.

    Science.gov (United States)

    Itu, Lucian; Sharma, Puneet; Georgescu, Bogdan; Kamen, Ali; Suciu, Constantin; Comaniciu, Dorin

    2014-01-01

    We introduce a model-based approach for the non-invasive estimation of patient specific, left ventricular PV loops. A lumped parameter circulation model is used, composed of the pulmonary venous circulation, left atrium, left ventricle and the systemic circulation. A fully automated parameter estimation framework is introduced for model personalization, composed of two sequential steps: first, a series of parameters are computed directly, and, next, a fully automatic optimization-based calibration method is employed to iteratively estimate the values of the remaining parameters. The proposed methodology is first evaluated for three healthy volunteers: a perfect agreement is obtained between the computed quantities and the clinical measurements. Additionally, for an initial validation of the methodology, we computed the PV loop for a patient with mild aortic valve regurgitation and compared the results against the invasively determined quantities: there is a close agreement between the time-varying LV and aortic pressures, time-varying LV volumes, and PV loops.

  2. Enthalpy-Based Thermal Evolution of Loops: III. Comparison of Zero-Dimensional Models

    Science.gov (United States)

    Cargill, P. J.; Bradshaw, Stephen J.; Klimchuk, James A.

    2012-01-01

    Zero dimensional (0D) hydrodynamic models, provide a simple and quick way to study the thermal evolution of coronal loops subjected to time-dependent heating. This paper presents a comparison of a number of 0D models that have been published in the past and is intended to provide a guide for those interested in either using the old models or developing new ones. The principal difference between the models is the way the exchange of mass and energy between corona, transition region and chromosphere is treated, as plasma cycles into and out of a loop during a heating-cooling cycle. It is shown that models based on the principles of mass and energy conservation can give satisfactory results at some, or, in the case of the Enthalpy Based Thermal Evolution of Loops (EBTEL) model, all stages of the loop evolution. Empirical models can lead to low coronal densities, spurious delays between the peak density and temperature, and, for short heating pulses, overly short loop lifetimes.

  3. Conventional Exergetic and Exergoeconomic Analyses of a Power Plant with Chemical Looping Combustion for CO2 Capture

    Directory of Open Access Journals (Sweden)

    Tatiana Morosuk

    2010-09-01

    Full Text Available

    Exergy-based methods can be used as a tool for examining, comparing and assessing thermodynamic systems. In this paper, an exergoeconomic analysis is used to evaluate a power plant with chemical looping combustion (CLC for CO2 capture. This oxy-fuel plant is compared, from an exergetic and an economic perspective, to a conventional, reference power plant without CO2 capture. The exergetic analysis shows decreased exergy destruction in the CLC reactors, compared to the exergy destruction in the conventional combustion chamber of the reference case; thus, the irreversibilities caused by combustion in the CLC are reduced. However, due to the addition of the CO2 compression unit, the overall exergetic efficiency of the plant with CLC is lower than that of the reference plant by approximately 5 percentage points. The economic analysis confirms a significant increase in the investment cost of the CO2 capture plant, due to the addition of the units for CO2 compression and CLC. Thus, the cost of electricity is 24% higher for this plant in comparison to that of the reference case. Nevertheless, when compared to the reference plant with CO2 capture with monoethanolamine, the plant with CLC was found to be a more economical option. Since CO2 abatement must be realized in the future, given expected environmental or tax measures, CLC provides relatively low cost carbon dioxide capture and it, therefore, appears to be a promising option for

  4. Enthalpy-Based Thermal Evolution of Loops: II. Improvements to the Model

    Science.gov (United States)

    Cargill, P. J.; Bradshaw, S. J.; Klimchuk, J. A.

    2011-01-01

    This paper further develops the zero-dimensional (0D) hydrodynamic coronal loop model "Enthalpy-based Thermal Evolution of Loops" (EBTEL) originally proposed by Klimchuk et al (2008), which studies the plasma response to evolving coronal heating. It has typically been applied to impulsive heating events. The basis of EBTEL is the modelling of mass exchange between the corona and transition region and chromosphere in response to heating variations, with the key parameter being the ratio of transition region to coronal radiation. We develop new models for this parameter that now include gravitational stratification and a physically motivated approach to radiative cooling. A number of examples are presented, including nanoflares in short and long loops, and a small flare. It is found that while the evolution of the loop temperature is rather insensitive to the details of the model, accurate tracking of the density requires the inclusion of our new features. In particular, we are able to now obtain highly over-dense loops in the late cooling phase and decreases to the coronal density arising due to stratification. The 0D results are compared to a 1D hydro code (Hydrad). The agreement is acceptable, with the exception of the flare case where some versions of Hydrad can give significantly lower densities. This is attributed to the method used to model the chromosphere in a flare. EBTEL is suitable for general use as a tool for (a) quick-look results of loop evolution in response to a given heating function and (b) situations where the modelling of hundreds or thousands of elemental loops is needed. A single run takes a few seconds on a contemporary laptop.

  5. Camera Based Closed Loop Control for Partial Penetration Welding of Overlap Joints

    Science.gov (United States)

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

    Welding of overlap joints with partial penetration in automotive applications is a challenging process, since the laser power must be set very precisely to achieve a proper connection between the two joining partners without damaging the backside of the sheet stack. Even minor changes in welding conditions can lead to bad results. To overcome this problem a camera based closed loop control for partial penetration welding of overlap joints was developed. With this closed loop control it is possible to weld such configurations with a stable process result even under changing welding conditions.

  6. Microwave photonic notch filter based on a dual-Sagnac-loop structure.

    Science.gov (United States)

    Wang, Xudong; Chan, Erwin H W; Minasian, Robert A

    2010-11-20

    A new single-wavelength, coherence-free microwave photonic notch filter is presented. The concept is based on a dual-Sagnac-loop structure that functions with a new principle in which the two loops operate with different free spectral ranges, and which generate noncommensurate taps. It has the ability to generate a narrow notch response and can operate to high frequencies. Experimental results demonstrate a notch filter with a narrow notch width, a flat passband, and high stop-band attenuation of over 40dB. PMID:21102681

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

    International Nuclear Information System (INIS)

    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 (800C); (ii) hydrofluoric plus nitric acid: 1.5% vol. HF + 5% vol. HNO3 at low temperature; 0.3 to 0.5% vol. HF + 2.5 to 5% vol. HNO3 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 m2 surface would typically produce 0.5 to 3.0 kg of dry waste, corresponding to 1.6 to 10 kg of concrete conditioned waste

  8. Sustainable Rent-Based Closed-Loop Supply Chain for Fashion Products

    Directory of Open Access Journals (Sweden)

    Zhi-Hua Hu

    2014-10-01

    Full Text Available The textile and clothing industry generates much pollution and consumes a large amount of resources. Improper uses and disposal of clothing products make the problems much more severe. Fast fashion products shorten the valid lifecycle and generate more waste than regular clothing products. Considering the features of fashion products, a system of a rent-based closed-loop supply chain is developed to improve the sustainability of fashion products. The supply chain processes (fashion design and manufacturing, laundry, logistics and disposal, the operations management issues (inventory management, closed-loop logistics, human-clothing matching, booking system and the rental pricing and the sustainability promotion aspects (customization, responsive system, culture and policy aspects are investigated by devising sustainable strategies. The rationalities of the developed system and strategies are reviewed and elucidated in detail. The results may contribute to building sustainable closed-loop fashion supply chains, the related information systems and operational and managerial mechanisms.

  9. Nonlinear Accelerator Problems via Wavelets; 8, Invariant Bases, Loops and KAM

    CERN Document Server

    Fedorova, A N; Fedorova, Antonina N.; Zeitlin, Michael G.

    1999-01-01

    In this series of eight papers we present the applications of methods from wavelet analysis to polynomial approximations for a number of accelerator physics problems. In this part we consider variational wavelet approach for loops, invariant bases on semidirect product, KAM calculation via FWT.

  10. Analysis of New Q-switched Erbium Doped Fiber Laser Based on Fiber Grating Loop Mirror

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An all-fiber wavelength selective Q-switching modulator based on fiber grating loop mirror is proposed. A newly configured Q-switched erbium doped fiber laser using this all-fiber modulator is numerically analyzed taking into account the effects of the spontaneous emission.

  11. Integrating a web-based system with business processes in closed loop supply chains

    NARCIS (Netherlands)

    A.I. Kokkinaki; R. Dekker (Rommert); R. Lee; C.P. Pappis (Costas)

    2001-01-01

    textabstractClosed Loop Supply Chains include operations for physical collection of end-of-use products, selection based on their configuration and/or condition and decision making for reuse, remanufacturing or recycling. Uncertainty factors regarding the time, place of origin, and status of retu

  12. 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

  13. Coal gasification integration with solid oxide fuel cell and chemical looping combustion for high-efficiency power generation with inherent CO2 capture

    International Nuclear Information System (INIS)

    Highlights: • A novel power system integrating coal gasification with SOFC and chemical looping combustion. • The plant net power efficiency reaches 49.8% with complete CO2 separation. • Energy and exergy analysis of the entire plant is conducted. • Sensitivity analysis shows a nearly constant power output when SOFC temperature and pressure vary. • NiO oxygen carrier shows higher plant efficiency than using Fe2O3 and CuO. - Abstract: Since solid oxide fuel cells (SOFC) produce electricity with high energy conversion efficiency, and chemical looping combustion (CLC) is a process for fuel conversion with inherent CO2 separation, a novel combined cycle integrating coal gasification, solid oxide fuel cell, and chemical looping combustion was configured and analyzed. A thermodynamic analysis based on energy and exergy was performed to investigate the performance of the integrated system and its sensitivity to major operating parameters. The major findings include that (1) the plant net power efficiency reaches 49.8% with ∼100% CO2 capture for SOFC at 900 °C, 15 bar, fuel utilization factor = 0.85, fuel reactor temperature = 900 °C and air reactor temperature = 950 °C, using NiO as the oxygen carrier in the CLC unit. (2) In this parameter neighborhood the fuel utilization factor, the SOFC temperature and SOFC pressure have small effects on the plant net power efficiency because changes in pressure and temperature that increase the power generation by the SOFC tend to decrease the power generation by the gas turbine and steam cycle, and v.v.; an advantage of this system characteristic is that it maintains a nearly constant power output even when the temperature and pressure vary. (3) The largest exergy loss is in the gasification process, followed by those in the CO2 compression and the SOFC. (4) Compared with the CLC Fe2O3 and CuO oxygen carriers, NiO results in higher plant net power efficiency. To the authors’ knowledge, this is the first analysis

  14. Floating Refrigerant Loop Based on R-134a Refrigerant Cooling of High-Heat Flux Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, K.T.

    2005-10-07

    The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) have been developing technologies to address the thermal issues associated with hybrid vehicles. Removal of the heat generated from electrical losses in traction motors and their associated power electronics is essential for the reliable operation of motors and power electronics. As part of a larger thermal control project, which includes shrinking inverter size and direct cooling of electronics, ORNL has developed U.S. Patent No. 6,772,603 B2, ''Methods and Apparatus for Thermal Management of Vehicle Systems and Components'' [1], and patent pending, ''Floating Loop System for Cooling Integrated Motors and Inverters Using Hot Liquid Refrigerant'' [2]. The floating-loop system provides a large coefficient of performance (COP) for hybrid-drive component cooling. This loop (based on R-134a) is integrated with a vehicle's existing air-conditioning (AC) condenser, which dissipates waste heat to the ambient air. Because the temperature requirements for cooling of power electronics and electric machines are not as low as that required for passenger compartment air, this adjoining loop can operate on the high-pressure side of the existing AC system. This arrangement also allows the floating loop to run without the need for the compressor and only needs a small pump to move the liquid refrigerant. For the design to be viable, the loop must not adversely affect the existing system. The loop should also provide a high COP, a flat-temperature profile, and low-pressure drop. To date, the floating-loop test prototype has successfully removed 2 kW of heat load in a 9 kW automobile passenger AC system with and without the automotive AC system running. The COP for the tested floating-loop system ranges from 40-45, as compared to a typical AC system COP of about 2-4. The estimated required waste-heat load for future hybrid

  15. Simple PID parameter tuning method based on outputs of the closed loop system

    Science.gov (United States)

    Han, Jianda; Zhu, Zhiqiang; Jiang, Ziya; He, Yuqing

    2016-05-01

    Most of the existing PID parameters tuning methods are only effective with pre-known accurate system models, which often require some strict identification experiments and thus infeasible for many complicated systems. Actually, in most practical engineering applications, it is desirable for the PID tuning scheme to be directly based on the input-output response of the closed-loop system. Thus, a new parameter tuning scheme for PID controllers without explicit mathematical model is developed in this paper. The paper begins with a new frequency domain properties analysis of the PID controller. After that, the definition of characteristic frequency for the PID controller is given in order to study the mathematical relationship between the PID parameters and the open-loop frequency properties of the controlled system. Then, the concepts of M-field and θ-field are introduced, which are then used to explain how the PID control parameters influence the closed-loop frequency-magnitude property and its time responses. Subsequently, the new PID parameter tuning scheme, i.e., a group of tuning rules, is proposed based on the preceding analysis. Finally, both simulations and experiments are conducted, and the results verify the feasibility and validity of the proposed methods. This research proposes a PID parameter tuning method based on outputs of the closed loop system.

  16. Looped out and perpendicular: deformation of Watson-Crick base pair associated with actinomycin D binding.

    Science.gov (United States)

    Chou, Shan-Ho; Chin, Ko-Hsin; Chen, Fu-Ming

    2002-05-14

    Many anticancer drugs interact directly with DNA to exert their biological functions. To date, all noncovalent, intercalating drugs interact with DNA exclusively by inserting their chromophores into base steps to form elongated and unwound duplex structures without disrupting the flanking base pairs. By using actinomycin D (ActD)-5'-GXC/CYG-5' complexes as examples, we have found a rather unusual interaction mode for the intercalated drug; the central Watson-Crick X/Y base pairs are looped out and displaced by the ActD chromophore. The looped-out bases are not disordered but interact perpendicularly with the base/chromophore and form specific H bonds with DNA. Such a complex structure provides intriguing insights into how ligand interacts with DNA and enlarges the repertoires for sequence-specific DNA recognition. PMID:12011426

  17. Looped out and perpendicular: Deformation of Watson–Crick base pair associated with actinomycin D binding

    Science.gov (United States)

    Chou, Shan-Ho; Chin, Ko-Hsin; Chen, Fu-Ming

    2002-01-01

    Many anticancer drugs interact directly with DNA to exert their biological functions. To date, all noncovalent, intercalating drugs interact with DNA exclusively by inserting their chromophores into base steps to form elongated and unwound duplex structures without disrupting the flanking base pairs. By using actinomycin D (ActD)-5′-GXC/CYG-5′ complexes as examples, we have found a rather unusual interaction mode for the intercalated drug; the central Watson–Crick X/Y base pairs are looped out and displaced by the ActD chromophore. The looped-out bases are not disordered but interact perpendicularly with the base/chromophore and form specific H bonds with DNA. Such a complex structure provides intriguing insights into how ligand interacts with DNA and enlarges the repertoires for sequence-specific DNA recognition. PMID:12011426

  18. Nanotube-Based Chemical and Biomolecular Sensors

    Institute of Scientific and Technical Information of China (English)

    J.Koh; B.Kim; S.Hong; H.Lim; H.C.Choi

    2008-01-01

    We present a brief review about recent results regarding carbon nanotube (CNT)-based chemical and biomolecular sensors. For the fabrication of CNT-based sensors, devices containing CNT channels between two metal electrodes are first fabricated usually via chemical vapor deposition (CVD) process or "surface programmed assembly" method. Then, the CNT surfaces are often functionalized to enhance the selectivity of the sensors. Using this process, highly-sensitive CNT-based sensors can be fabricated for the selective detection of various chemical and biological molecules such as hydrogen, ammonia, carbon monoxide, chlorine gas, DNA, glucose, alcohol, and proteins.

  19. 惰性载体Al_2O_3对Fe_2O_3及CuO氧载体煤化学链燃烧的影响%Effect of Inert Support Al_2O_3 on the Chemical Looping Combustion of Coal With Fe_2O_3 and CuO-based Oxygen Carrier

    Institute of Scientific and Technical Information of China (English)

    王保文; 赵海波; 郑瑛; 柳朝晖; 郑楚光; 晏蓉

    2011-01-01

    氧载体是煤化学链燃烧技术的基础,惰性载体则是其中的必要组成部分,起着重要的作用。以Al2O3作为典型惰性载体,采用热重分析仪、红外频谱仪、场发射扫描电镜和能谱分析仪以及X衍射仪,对六盘水贫煤与Fe2O3、CuO基氧载体的反应进行了详细的研究。研究发现,Al2O3的引入,使得Fe2O3、CuO基氧载体表面积增大、孔径分布更为优化,而且对氧载体与六盘水贫煤一次热解产物的反应是有利的,能够促进氧载体中更多晶格氧的传递,Fe2O3基氧载体中有更多的Fe2O3还原为低于Fe3O4价态的氧化物,而CuO基氧载体中CuO除了还原为Cu、Cu2O外,其中的CuAl2O4也有一定的反应活性,被还原为CuAlO2。与LPS煤反应时,Fe2O3深度还原产物与部分Al2O3及煤中的SiO2反应生成Fe3Al2(SiO4)3,而CuO则与Al2O3及六盘水贫煤反应生成了(Cu0.215Mg1.785)(Al4Si5O18)复合物。%Oxygen carrier(OC) is the basis for chemical looping combustion of coal and inert support is the necessary part of OC.Al2O3 was adopted as the typical inert support and the reaction of Liupanshui(LPS) coal with Fe2O3,CuO based OC was systematically investigated by various experimental means,including thermogravimetric analysis(TGA),Fourier transform infrared spectroscopy(FTIR),field scanning electron microscopy coupled with energy-dispersive X-ray spectrometry(FSEM-EDX) and X-ray diffraction(XRD) analysis.It was found that,the introduction of Al2O3 to Fe2O3 and CuO made the surface areas of these two OC greatly increased and the pore distribution more optimized,which benefited the primary gaseous products of LPS coal to react with Fe2O3 and CuO.Furthermore,during the reaction of LPS with these two OC,the optimized pore size distribution promoted more sufficient reaction of LPS coal with Fe2O3,and thus more Fe2O3 was reduced into lower valence oxides than Fe3O4;but for CuO based OC,their solid reduced products with

  20. Closed-loop enhancement of jet mixing with extremum-seeking and physics-based strategies

    Science.gov (United States)

    Wu, Z.; Zhou, Y.; Cao, H. L.; Li, W. J.

    2016-06-01

    The closed-loop control of a turbulent round air jet is experimentally investigated based on two unsteady minijets, with a view to enhancing jet mixing. The two minijets are placed at diametrically opposite locations upstream of the nozzle exit. The open-loop control experiments are first performed. Given the mass flow rate ratio C m of the minijets to that of the main jet, the decay rate overline{K} of jet centerline mean velocity exhibits a maximum at the frequency ratio f e/ f 0 ≈ 1.0, where f e and f 0 are the excitation frequency of minijets and the preferred mode frequency of the natural main jet, respectively. An extremum-seeking feedback control has been developed to achieve autonomously the optimal control performance. It has been found that, given C m, this closed-loop control technique may obtain automatically and rapidly the optimal value of f e and the desired or maximum overline{K}, as achieved in the open-loop control. This control technique is robust and adaptable when the Reynolds number and initial excitation frequency are changed separately. A flow-physics-based feedback control strategy has also been investigated, which could achieve the optimal control performance automatically with a shorter convergence time than the extremum-seeking control, not robust though.

  1. Transparent Runtime Migration of Loop-Based Traces of Processor Instructions to Reconfigurable Processing Units

    Directory of Open Access Journals (Sweden)

    João Bispo

    2013-01-01

    Full Text Available The ability to map instructions running in a microprocessor to a reconfigurable processing unit (RPU, acting as a coprocessor, enables the runtime acceleration of applications and ensures code and possibly performance portability. In this work, we focus on the mapping of loop-based instruction traces (called Megablocks to RPUs. The proposed approach considers offline partitioning and mapping stages without ignoring their future runtime applicability. We present a toolchain that automatically extracts specific trace-based loops, called Megablocks, from MicroBlaze instruction traces and generates an RPU for executing those loops. Our hardware infrastructure is able to move loop execution from the microprocessor to the RPU transparently, at runtime, and without changing the executable binaries. The toolchain and the system are fully operational. Three FPGA implementations of the system, differing in the hardware interfaces used, were tested and evaluated with a set of 15 application kernels. Speedups ranging from 1.26 to 3.69 were achieved for the best alternative using a MicroBlaze processor with local memory.

  2. ENTHALPY-BASED THERMAL EVOLUTION OF LOOPS. III. COMPARISON OF ZERO-DIMENSIONAL MODELS

    International Nuclear Information System (INIS)

    Zero-dimensional (0D) hydrodynamic models provide a simple and quick way to study the thermal evolution of coronal loops subjected to time-dependent heating. This paper presents a comparison of a number of 0D models that have been published in the past and is intended to provide a guide for those interested in either using the old models or developing new ones. The principal difference between the models is the way the exchange of mass and energy between corona, transition region, and chromosphere is treated, as plasma cycles into and out of a loop during a heating-cooling cycle. It is shown that models based on the principles of mass and energy conservation can give satisfactory results at some or, in the case of the Enthalpy-based Thermal Evolution of Loops model, all stages of the loop evolution. Empirical models can have significant difficulties in obtaining accurate behavior due to invocation of assumptions incompatible with the correct exchange of mass and energy between corona, transition region, and chromosphere.

  3. Enthalpy-based Thermal Evolution of Loops: II. Improvements to the Model

    CERN Document Server

    Cargill, Peter J; Klimchuk, James A

    2012-01-01

    This paper develops the zero-dimensional (0D) hydrodynamic coronal loop model "Enthalpy-based Thermal Evolution of Loops" (EBTEL) proposed by Klimchuk et al (2008), which studies the plasma response to evolving coronal heating, especially impulsive heating events. The basis of EBTEL is the modelling of mass exchange between the corona and transition region and chromosphere in response to heating variations, with the key parameter being the ratio of transition region to coronal radiation. We develop new models for this parameter that now include gravitational stratification and a physically motivated approach to radiative cooling. A number of examples are presented, including nanoflares in short and long loops, and a small flare. The new features in EBTEL are important for accurate tracking of, in particular, the density. The 0D results are compared to a 1D hydro code (Hydrad) with generally good agreement. EBTEL is suitable for general use as a tool for (a) quick-look results of loop evolution in response to ...

  4. A digital phase locked loop based signal and symbol recovery system for wireless channel

    CERN Document Server

    Purkayastha, Basab Bijoy

    2015-01-01

    The book reports two approaches of implementation of the essential components of a Digital Phase Locked Loop based system for dealing with wireless channels showing Nakagami-m fading. It is mostly observed in mobile communication. In the first approach, the structure of a Digital phase locked loop (DPLL) based on Zero Crossing (ZC) algorithm is proposed. In a modified form, the structure of a DPLL based systems for dealing with Nakagami-m fading based on Least Square Polynomial Fitting Filter is proposed, which operates at moderate sampling frequencies. A sixth order Least Square Polynomial Fitting (LSPF) block and Roots Approximator (RA) for better phase-frequency detection has been implemented as a replacement of Phase Frequency Detector (PFD) and Loop Filter (LF) of a traditional DPLL, which has helped to attain optimum performance of DPLL. The results of simulation of the proposed DPLL with Nakagami-m fading and QPSK modulation is discussed in detail which shows that the proposed method provides better pe...

  5. Study on the dynamic performance of a novel buck-boost matrix converter based on double-loop control strategy

    Science.gov (United States)

    Li, Qing; Zhang, Xiao-ping; Chen, Qi

    2011-12-01

    The dynamic performance of a novel Buck-Boost matrix converter (BBMC) based on double-loop control strategy is put forward in this paper. The fundamental principle of BBMC has been elaborated and the method of the double-loop control strategy has been built with Matlab, and then the dynamic performances of BBMC based on the double-loop control strategy are discussed. The results show that the output voltage and frequency can be almost constant with the BBMC and double-loop control strategy despite of the changeable input voltage and frequency. Moreover, a high-quality sine output wave with low harmonic distortion can be directly obtained without filtering. So it can be drawn that the BBMC based on the double-loop control strategy has perfectly dynamic performance and practical importance to the engineering.

  6. DSP based software phase locked loop for inverter stage of dynamic voltage restorer

    International Nuclear Information System (INIS)

    Phase Locked Loop (PLL) has been advantageously used as a control system tool in telecommunication engineering, radar, sonar, control and power engineering. These are crucial to grid connected power converters applied to power factor control, active power filters, grid monitoring in distributed power generation systems, Flexible AC Transmission Systems (FACTS), etc. Software PLL (SPLL) is a derivative of the PLL system with its loop components implemented entirely in computer code and is possible to implement if the signals are entirely digitized. Digital Signal Processors (DSP) based controllers with fast sampling ADCs have allowed easier implementation of the SPLLs in power converter systems. The paper illustrates the design, development and implementation of a SPLL used in the Voltage Source Inverter (VSI) stage of a Superconducting Magnetic Energy Storage System (SMES) based Dynamic Voltage Restorer (DVR) for voltage sag mitigation to provide quality power for R and D laboratories like VECC

  7. IMC-PID design based on model matching approach and closed-loop shaping.

    Science.gov (United States)

    Jin, Qi B; Liu, Q

    2014-03-01

    Motivated by the limitations of the conventional internal model control (IMC), this communication addresses the design of IMC-based PID in terms of the robust performance of the control system. The IMC controller form is obtained by solving an H-infinity problem based on the model matching approach, and the parameters are determined by closed-loop shaping. The shaping of the closed-loop transfer function is considered both for the set-point tracking and for the load disturbance rejection. The design procedure is formulated as a multi-objective optimization problem which is solved by a specific optimization algorithm. A nice feature of this design method is that it permits a clear tradeoff between robustness and performance. Simulation examples show that the proposed method is effective and has a wide applicability.

  8. IMC-PID design based on model matching approach and closed-loop shaping.

    Science.gov (United States)

    Jin, Qi B; Liu, Q

    2014-03-01

    Motivated by the limitations of the conventional internal model control (IMC), this communication addresses the design of IMC-based PID in terms of the robust performance of the control system. The IMC controller form is obtained by solving an H-infinity problem based on the model matching approach, and the parameters are determined by closed-loop shaping. The shaping of the closed-loop transfer function is considered both for the set-point tracking and for the load disturbance rejection. The design procedure is formulated as a multi-objective optimization problem which is solved by a specific optimization algorithm. A nice feature of this design method is that it permits a clear tradeoff between robustness and performance. Simulation examples show that the proposed method is effective and has a wide applicability. PMID:24280534

  9. Determination of Optimal Opening Scheme for Electromagnetic Loop Networks Based on Fuzzy Analytic Hierarchy Process

    Directory of Open Access Journals (Sweden)

    Yang Li

    2016-01-01

    Full Text Available Studying optimization and decision for opening electromagnetic loop networks plays an important role in planning and operation of power grids. First, the basic principle of fuzzy analytic hierarchy process (FAHP is introduced, and then an improved FAHP-based scheme evaluation method is proposed for decoupling electromagnetic loop networks based on a set of indicators reflecting the performance of the candidate schemes. The proposed method combines the advantages of analytic hierarchy process (AHP and fuzzy comprehensive evaluation. On the one hand, AHP effectively combines qualitative and quantitative analysis to ensure the rationality of the evaluation model; on the other hand, the judgment matrix and qualitative indicators are expressed with trapezoidal fuzzy numbers to make decision-making more realistic. The effectiveness of the proposed method is validated by the application results on the real power system of Liaoning province of China.

  10. An All-fiber Temperature Sensor Based on a Macro-bend Singlemode Fiber Loop

    OpenAIRE

    Rajan, Ginu; Semenova, Yuliya; Farrell, Gerald

    2008-01-01

    An all-fibre temperature sensor is proposed based on a macro-bend singlemode fibre loop using a ratiometric power measurement scheme. The sensor has a linear characteristic with temperature at a fixed wavelength and bend radius. A direct linear relationship between the bend loss of the singlemode fibre and temperature is reported for the first time. By measuring the change in bend loss of the system a change in temperature can be measured assuming the system is calibrated. The proposed sensor...

  11. A tunable comb filter using single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop

    Institute of Scientific and Technical Information of China (English)

    Ruan Juan; Zhang Wei-Gang; Zhang Hao; Geng Peng-Cheng; Bai Zhi-Yong

    2013-01-01

    A novel tunable comb filter composed of a single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop is proposed and experimentally demonstrated.The filter tunability is achieved by rotating the polarization controller.The spectral shift is dependent on rotation direction and the position of the polarization controller.In addition,the adjustable range achieved by rotating the half-wave-plate polarization controller is twice higher than that of the quarter-wave-plate one.

  12. Site-directed mutagenesis of the base recognition loop of ribonuclease from Bacillus intermedius (binase).

    Science.gov (United States)

    Okorokov, A L; Panov, K I; Kolbanovskaya EYu; Karpeisky MYa; Polyakov, K M; Wilkinson, A J; Dodson, G G

    1996-04-15

    Members of the microbial guanyl-specific ribonuclease family show a high level of structural homology. The structural basis for guanyl base binding by microbial ribonucleases has been established for all members of the family and the existence of a guanine recognition loop was shown. However, bacillar RNases such as binase and barnase show far less specificity towards the guanyl base in hydrolysing oligonucleotides composed of more than 4 or 5 nucleotides. Using site-directed mutagenesis we introduced a number of amino acid substitutions into the base recognition loop of binase. The donor sequence originated from the guanyl specific ribonuclease Sa. Two single, two double and one triple (entire loop substitution) mutants were constructed and overproduced in E. coli. The kinetic properties of the mutant variants are different from the wild-type protein. Amino acid substitutions R61V, G60S, S56Q/R61V, G60S/R61V show 3-fold, 7-fold, 4-fold and 12-fold increased guanyl specificity respectively. However, all mutants retain the ability to catalyse the hydrolysis of a poly(A) substrate. PMID:8612811

  13. 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.

  14. Neural-network-based two-loop control of robotic manipulators including actuator dynamics in task space

    Institute of Scientific and Technical Information of China (English)

    Liangyong WANG; Tianyou CHAI; Zheng FANG

    2009-01-01

    A neural-network-based motion controller in task space is presented in this paper. The proposed controller is addressed as a two-loop cascade control scheme. The outer loop is given by kinematic control in the task space. It provides a joint velocity reference signal to the inner one. The inner loop implements a velocity servo loop at the robot joint level. A radial basis function network (RBFN) is integrated with proportional-integral (PI) control to construct a velocity tracking control scheme for the inner loop. Finally, a prototype technology based control system is designed for a robotic manipulator. The proposed control scheme is applied to the robotic manipulator. Experimental results confirm the validity of the proposed control scheme by comparing it with other control strategies.

  15. Looped out and perpendicular: Deformation of Watson–Crick base pair associated with actinomycin D binding

    OpenAIRE

    Chou, Shan-Ho; Chin, Ko-Hsin; Chen, Fu-Ming

    2002-01-01

    Many anticancer drugs interact directly with DNA to exert their biological functions. To date, all noncovalent, intercalating drugs interact with DNA exclusively by inserting their chromophores into base steps to form elongated and unwound duplex structures without disrupting the flanking base pairs. By using actinomycin D (ActD)-5′-GXC/CYG-5′ complexes as examples, we have found a rather unusual interaction mode for the intercalated drug; the central Watson–Crick X/Y base pairs are looped ou...

  16. Tracking Positioning Algorithm for Direction of Arrival Based on Direction Lock Loop

    Directory of Open Access Journals (Sweden)

    Xiu-Zhi Cheng

    2015-06-01

    Full Text Available In order to solve the problem of poor real-time performance, low accuracy and high computational complexity in the traditional process of locating and tracking of Direction of Arrival (DOA of moving targets, this paper proposes a DOA algorithm based on the Direction Lock Loop (DILL which adopts Lock Loop structure to realize the estimation and location of DOA and can adjust the direction automatically along with the changes of a signal’s angular variation to track the position of the signal. Meanwhile, to reduce the influence of nonlinearity and noise on its performance, the UKF filter is designed for eliminating interference of the estimated target signal to improve accuracy of the signal tracking and stability of the system. Simulation results prove that the algorithm can not only get a high resolution DOA estimate signal, but can also locate and track multiple mobile targets effectively with enhanced accuracy, efficiency and stability.

  17. Hardware-in the-loop Simulator for ABS based on MATLAB/Simulink

    Institute of Scientific and Technical Information of China (English)

    Pan,Wei; Gao,jinghui; Zhou,Yafu; Song,Zhenhuan

    2003-01-01

    A method for building a Hardware-in the-loop Simulator of ABS base on MATLAB/Simulink is presented in this paper. In this method, the vehicle transmission model, the AT model and ABS algorithm is built in Simulink. This system can simulate a vehicle system in the Simulink environment. Further more, the Hardware-in the-loop Simulator system can be connected with the real ABS by I/O boards to observe the algorithm is reasonable or not. At the same time, user can simulate some different conditions by changing the parameter. The system help the user heightening the efficiency when developing the electronic device. Also, the system can be used as teaching demo software.

  18. Closed Loop Control of Active Damped Small DC-link Capacitor Based Drive

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig

    2010-01-01

    A new method of active damping for small DC-link capacitor based drive system is implemented in stator flux oriented control for an induction machine. The active damping technique is based on a detailed model of the drive system which leads to a very simple implementation. The active damping can...... be achieved either by modifying the machine current reference or by modifying the machine voltage. The correlation between these two methods is shown by using simple analysis and it is verified by experimental results in a three phase induction machine drive. The effect of current control loop bandwidth...

  19. Multi-loop adaptive internal model control based on a dynamic partial least squares model

    Institute of Scientific and Technical Information of China (English)

    Zhao ZHAO; Bin HU; Jun LIANG

    2011-01-01

    A multi-loop adaptive internal model control (IMC) strategy based on a dynamic partial least squares (PLS) framework is proposed to account for plant model errors caused by slow aging, drift in operational conditions, or environmental changes. Since PLS decomposition structure enables multi-loop controller design within latent spaces, a multivariable adaptive control scheme can be converted easily into several independent univariable control loops in the PLS space. In each latent subspace,once the model error exceeds a specific threshold, online adaptation rules are implemented separately to correct the plant model mismatch via a recursive least squares (RLS) algorithm. Because the IMC extracts the inverse of the minimum part of the internal model as its structure, the IMC controller is self-tuned by explicitly updating the parameters, which are parts of the internal model.Both parameter convergence and system stability are briefly analyzed, and proved to be effective. Finally, the proposed control scheme is tested and evaluated using a widely-used benchmark of a multi-input multi-output (MIMO) system with pure delay.

  20. Experiments of char particle segregation effect on the gas conversion behavior in the fuel reactor for chemical looping combustion

    International Nuclear Information System (INIS)

    Highlights: • This work verified the existence of char particle segregation in the fuel reactor during CLC. • The char particle segregation has detrimental effect on the conversion of the char gasification product CO. • Larger/heavier char particles located near the reactor bottom have a higher CO conversion than the smaller/lighter char. • Larger fluidizing gas velocity can reduce the effect of char segregation on CO conversion. • Oxygen carriers of high reactivity can convert CO completely although segregation effect exists. - Abstract: In solid fuel (such as lignite) chemical looping combustion, solid fuels undergo pyrolysis and gasification. The volatiles from pyrolysis and the gasification product (CO/H2) react with oxygen carriers. The gas conversion (to CO2/H2O) in the fuel reactor is a key point. However, char particles of different sizes and conversion ratios cause segregation in the fuel reactor, which influences the contact time between fuel gases and the carrier, thereby changing the gas conversion behavior. In order to gain information on obtaining a high gas conversion in the fuel reactor, this work focused on the effect of the char particle segregation on gas conversion. Different factors – the char particle size, the fluidizing gas velocity, and the oxygen carrier reactivity – were taken into account. Smaller char particles with low density would float on top of the fluidized bed, corresponding to a low gas conversion (mf in the Fe63Al bed) can reduce the segregation effect, resulting in a higher CO conversion. High reactivity carriers can convert CO completely although segregation exists, whereas low reactivity carriers exhibit the segregation effect and thus corresponds to a low CO conversion

  1. Application of Fe2O3/Al2O3 Composite Particles as Oxygen Carrier of Chemical Looping Combustion

    Institute of Scientific and Technical Information of China (English)

    Fang He; Hua Wang; Yongnian Dai

    2007-01-01

    Chemical looping combustion (CLC) of carbonaceous compounds has been proposed, in the past decade, as an efficient method for CO2 capture without cost of extra energy penalties. The technique involves the use of a metal oxide as an oxygen carrier that transfers oxygen from combustion air to fuels.The combustion is carried out in a two-step process: in the fuel reactor, the fuel is oxidized by a metal oxide, and in the air reactor, the reduced metal is oxidized back to the original phase. The use of iron oxide as an oxygen carrier has been investigated in this article. Particles composed of 80 wt% Fe2O3,together with Al2O3 as binder, have been prepared by impregnation methods. X-ray diffraction (XRD) analysis reveals that Fe2O3 does not interact with the Al2O3 binder after multi-cycles. The reactivity of the oxygen carrier particles has been studied in twenty-cycle reduction-oxidation tests in a thermal gravimetrical analysis (TGA) reactor. The components in the outlet gas have been analyzed. It has been observed that about 85% of CH4 converted to CO2 and H2O during most of the reduction periods. The oxygen carrier has kept quite a high reactivity in the twenty-cycle reactions. In the first twenty reaction cycles, the reaction rates became slightly higher with the number of cyclic reactions increasing, which was confirmed by the scanning electron microscopy (SEM) test results. The SEM analysis revealed that the pore size inside the particle had been enlarged by the thermal stress during the reaction, which was favorable for diffusion of the gaseous reactants into the particles. The experimental results suggested that the Fe2O3/Al2O3 oxygen carrier was a promising candidate for a CLC system.

  2. Clustering of HIV-1 Subtypes Based on gp120 V3 Loop electrostatic properties

    Directory of Open Access Journals (Sweden)

    López de Victoria Aliana

    2012-02-01

    Full Text Available Abstract Background The V3 loop of the glycoprotein gp120 of HIV-1 plays an important role in viral entry into cells by utilizing as coreceptor CCR5 or CXCR4, and is implicated in the phenotypic tropisms of HIV viruses. It has been hypothesized that the interaction between the V3 loop and CCR5 or CXCR4 is mediated by electrostatics. We have performed hierarchical clustering analysis of the spatial distributions of electrostatic potentials and charges of V3 loop structures containing consensus sequences of HIV-1 subtypes. Results Although the majority of consensus sequences have a net charge of +3, the spatial distribution of their electrostatic potentials and charges may be a discriminating factor for binding and infectivity. This is demonstrated by the formation of several small subclusters, within major clusters, which indicates common origin but distinct spatial details of electrostatic properties. Some of this information may be present, in a coarse manner, in clustering of sequences, but the spatial details are largely lost. We show the effect of ionic strength on clustering of electrostatic potentials, information that is not present in clustering of charges or sequences. We also make correlations between clustering of electrostatic potentials and net charge, coreceptor selectivity, global prevalence, and geographic distribution. Finally, we interpret coreceptor selectivity based on the N6X7T8|S8X9 sequence glycosylation motif, the specific positive charge location according to the 11/24/25 rule, and the overall charge and electrostatic potential distribution. Conclusions We propose that in addition to the sequence and the net charge of the V3 loop of each subtype, the spatial distributions of electrostatic potentials and charges may also be important factors for receptor recognition and binding and subsequent viral entry into cells. This implies that the overall electrostatic potential is responsible for long-range recognition of the V3

  3. A linear coherent integrated receiver based on a broadband optical phase-locked loop

    Science.gov (United States)

    Ramaswamy, Anand

    Optical Phase-Locked Loops (OPLL) have diverse applications in future communication systems. They can be used in high sensitivity homodyne phase-shift keying receivers for phase noise reduction, provided sufficient loop bandwidth is maintained. Alternative phase-locked loop applications include coherent synchronization of laser arrays and frequency synthesis by offset locking. In this work, a broadband OPLL based coherent receiver is used for linear phase demodulation. Phase modulated (PM) analog optical links have the potential to outperform conventional direct detection links. However, their progress has been stymied by the lack of a linear phase demodulator. We describe how feedback can be used to suppress non-linearities arising from the phase demodulation process. The receiver concept is demonstrated at low frequencies and is found to improve the Spurious Free Dynamic Range (SFDR) of an experimental analog link by over 20dB. In order to extend the operation of the receiver to microwave frequencies, latencies arising from physical delays in the feedback path need to be dramatically reduced. To facilitate this, monolithic and hybrid versions of the receiver based on compact integration of InP photonic integrated circuits (PIC) with InP and SiGe electronic integrated circuits (EIC) have been developed at UCSB. In this work, we develop novel measurement techniques to characterize the linearity of the individual components of the PIC, namely, the semiconductor photodiodes and optical phase modulators. We then demonstrate the operation of the receiver in a high power analog link. The OPLL based receiver has a bandwidth of 1.5GHz. The link gain and shot-noise limited SFDR at 300MHz are -2dB and 125dB-Hz2/3, respectively. Further, optical sampling downconversion is demonstrated as a viable technique to increase the operating frequency of the receiver beyond the baseband range.

  4. Low-Bandwidth Operation of TES-Based Bolometer Operation in a Resistance Locked Loop

    Science.gov (United States)

    van der Kuur, J.; Gottardi, L.; Akamatsu, H.; Bruijn, M.; den Hartog, R.; Hoevers, H.; Gao, J. R.; Hijmering, R.; Khosropanah, P.; Ridder, M.

    2014-08-01

    Operation of TES-based bolometers in a resistance locked loop (RLL), i.e. keeping the operating resistance constant by means of feedback on the bias voltage, provides a number of attractive properties for applications. In combination with frequency domain multiplexing, the technique reduces electrical cross talk, and provides a more detector load independent behaviour with respect to operation under standard voltage bias. This paper shows a quantitative estimation of the large signal properties under the RLL, and shows a comparison with the situation under voltage bias. Furthermore, an unorthodox, low-bandwidth mode of operation will be discussed, from the perspective of the electro-thermal stability in the RLL.

  5. Matlab Based Human & Hardware-in-Loop Simulation for the Study on Vehicle Stability Control

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper described an effective method to implement human & hardware in the loop simulation (HHILS), which is based on MATLAB system and can be used to study human driving actions in the abrupt situation and vehicle stability control(VSC). A hybrid control algorithm, which makes full use of the advantages of robust control and fuzzy logic, was adopted in VSC system. The results of HHILS show that HHILS' application on the vehicle handling and VSC resarch is feasible. These results also confirm that the handling performance of the vehicle with VSC is improved obviously compared to the vehicle without VSC.

  6. Principle and Implementation of an MC4044-Based Phase Locked Loop for Constant Speed Control

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An inexpensive MC4044-based phase locked loop for constant speed control of a DC motor is discussed. It operates on a principle similar to that of a frequency synthesizer. The paper introduces the system configuration with a detailed description of its operating principle, some practical design considerations are discussed with an experimental study to test the control performance of the newly designed system. The experimental result shows that the phase locked control system can regulate the speed of a DC torque motor with a precision up to 0.0022%(1σ).

  7. Low-Profile Magnetic Loop Monopole Antenna Based on a Square Substrate-Integrated Cavity

    OpenAIRE

    Thomas Kaufmann; Christophe Fumeaux

    2015-01-01

    A low-profile monopole antenna with height below λ0/16 is proposed. The antenna is based on a square substrate-integrated cavity radiating through apertures in its four side walls. This effectively creates a small square loop of magnetic currents, which radiates omnidirectionally as an electric monopole. The antenna cavity has a side length of less than λ0/3 and thus resonates in the monomode region, in a fundamental TM11 mode. This means that the structure is robust in ter...

  8. 20/30 GHz dual-band circularly polarized reflectarray antenna based on the concentric dual split-loop element

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst; Vesterdal Larsen, Niels; Vesterager Gothelf, Ulrich;

    2012-01-01

    A concentric dual split-loop element is designed and investigated for reflectarray antenna design in the emerging 20 GHz and 30 GHz Ka-band satellite communication spectrum. The element is capable of providing adjustment of the phase of reflection coefficients for circular plane waves in two...... separate frequency bands, by rotation of the individual split-loops. Cross-polar reflection is simultaneously minimized by optimizing the gaps in the split-loops. Based on the element characteristics, an iterative design procedure is proposed and used to design a front-fed reflectarray antenna...

  9. Single-phase Phase-locked Loop Based on Derivative Elements

    DEFF Research Database (Denmark)

    Guan, Qingxin; Zhang, Yu; Kang, Yong;

    2016-01-01

    High performance phase locked loops (PLLs) are critical for power control in grid-connected systems. This paper presents a new method of designing a PLL for single-phase systems based on derivative elements (DEs). The quadrature signal generator (QSG) is constructed by two DEs with the same main...... parameters. The PLL itself is realized by using the DE-based QSG. It avoids errors due to the overlap and accumulation that are present in PLLs based on integral elements, such as a PLL based on a second-order generalized integrator (SOGI-PLL). Additionally, frequency feedback is not needed which allows...... the proposed PLL to achieve high performance when the grid frequency changes rapidly. This paper presents the model of the PLL and a theoretical performance analysis with respect to both the frequency-domain and time-domain behavior. The error arising from the discretization process is also compensated...

  10. Cryogenic Phase-Locking Loop System Based on SIS Tunnel Junction

    Science.gov (United States)

    Khudchenko, A. V.; Koshelets, V. P.; Kalashnikov, K. V.

    An ultra-wideband cryogenic phase-locking loop (CPLL) system is a new cryogenic device. The CPLL is intended for phase-locking of a Flux-Flow Oscillator (FFO) in a Superconducting Integrated Receiver (SIR) but can be used for any cryogenic terahertz oscillator. The key element of the CPLL is Cryogenic Phase Detector (CPD), a recently proposed new superconducting element. The CPD is an innovative implementation of superconductor-insulator-superconductor (SIS) tunnel junction. All components of the CPLL reside inside a cryostat at 4.2 K, with the loop length of about 50 cm and the total loop delay 5.5 ns. Such a small delay results in CPLL synchronization bandwidth as wide as 40 MHz and allows phase-locking of more than 60% of the power emitted by the FFO even for FFO linewidth of about 10 MHz. This percentage of phase-locked power three times exceeds that achieved with conventional room-temperature PLLs. Such an improvement enables reducing the FFO phase noise and extending the SIR operation range.Another new approach to the FFO phase-locking has been proposed and experimentally verified. The FFO has been synchronized by a cryogenic harmonic phase detector (CHPD) based on the SIS junction. The CHPD operates simultaneously as the harmonic mixer (HM) and phase detector. We have studied the HM based on the SIS junction theoretically; in particular we calculated 3D dependences of the HM output signal power versus the bias voltage and the LO power. Results of the calculations have been compared with experimental measurements. Good qualitative and quantitative correspondence has been achieved. The FFO phase-locking by the CHPD has been demonstrated. Such a PLL system is expected to be extra wideband. This concept is very promising for building of the multi-pixel SIR array.

  11. Chemical Sensors Based on Optical Ring Resonators

    Science.gov (United States)

    Homer, Margie; Manfreda, Allison; Mansour, Kamjou; Lin, Ying; Ksendzov, Alexander

    2005-01-01

    Chemical sensors based on optical ring resonators are undergoing development. A ring resonator according to this concept is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, is a made of a polymer that (1) has an index of refraction lower than that of the waveguide core and (2) absorbs chemicals from the surrounding air. The index of refraction of the polymer changes with the concentration of absorbed chemical( s). The resonator is designed to operate with relatively strong evanescent-wave coupling between the outer polymer layer and the electromagnetic field propagating along the waveguide core. By virtue of this coupling, the chemically induced change in index of refraction of the polymer causes a measurable shift in the resonance peaks of the ring. In a prototype that has been used to demonstrate the feasibility of this sensor concept, the ring resonator is a dielectric optical waveguide laid out along a closed path resembling a racetrack (see Figure 1). The prototype was fabricated on a silicon substrate by use of standard techniques of thermal oxidation, chemical vapor deposition, photolithography, etching, and spin coating. The prototype resonator waveguide features an inner cladding of SiO2, a core of SixNy, and a chemical-sensing outer cladding of ethyl cellulose. In addition to the ring Chemical sensors based on optical ring resonators are undergoing development. A ring resonator according to this concept is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, is a made of a polymer that (1) has an index of refraction lower than that of the waveguide core and (2) absorbs chemicals from the surrounding air. The index of refraction of the polymer changes with the concentration of absorbed chemical( s). The resonator is designed to operate with relatively strong

  12. Reduced Moment-Based Models for Oxygen Precipitates and Dislocation Loops in Silicon

    Science.gov (United States)

    Trzynadlowski, Bart

    The demand for ever smaller, higher-performance integrated circuits and more efficient, cost-effective solar cells continues to push the frontiers of process technology. Fabrication of silicon devices requires extremely precise control of impurities and crystallographic defects. Failure to do so not only reduces performance, efficiency, and yield, it threatens the very survival of commercial enterprises in today's fiercely competitive and price-sensitive global market. The presence of oxygen in silicon is an unavoidable consequence of the Czochralski process, which remains the most popular method for large-scale production of single-crystal silicon. Oxygen precipitates that form during thermal processing cause distortion of the surrounding silicon lattice and can lead to the formation of dislocation loops. Localized deformation caused by both of these defects introduces potential wells that trap diffusing impurities such as metal atoms, which is highly desirable if done far away from sensitive device regions. Unfortunately, dislocations also reduce the mechanical strength of silicon, which can cause wafer warpage and breakage. Engineers must negotiate this and other complex tradeoffs when designing fabrication processes. Accomplishing this in a complex, modern process involving a large number of thermal steps is impossible without the aid of computational models. In this dissertation, new models for oxygen precipitation and dislocation loop evolution are described. An oxygen model using kinetic rate equations to evolve the complete precipitate size distribution was developed first. This was then used to create a reduced model tracking only the moments of the size distribution. The moment-based model was found to run significantly faster than its full counterpart while accurately capturing the evolution of oxygen precipitates. The reduced model was fitted to experimental data and a sensitivity analysis was performed to assess the robustness of the results. Source

  13. Efficient Closed-Loop Schemes for MIMO-OFDM-Based WLANs

    Directory of Open Access Journals (Sweden)

    Jiang Yi

    2006-01-01

    Full Text Available The single-input single-output (SISO orthogonal frequency-division multiplexing (OFDM systems for wireless local area networks (WLAN defined by the IEEE 802.11a standard can support data rates up to 54 Mbps. In this paper, we consider deploying two transmit and two receive antennas to increase the data rate up to 108 Mbps. Applying our recent multiple-input multiple-output (MIMO transceiver designs, that is, the geometric mean decomposition (GMD and the uniform channel decomposition (UCD schemes, we propose simple and efficient closed-loop MIMO-OFDM designs for much improved performance, compared to the standard singular value decomposition (SVD based schemes as well as the open-loop V-BLAST (vertical Bell Labs layered space-time based counterparts. In the explicit feedback mode, precoder feedback is needed for the proposed schemes. We show that the overhead of feedback can be made very moderate by using a vector quantization method. In the time-division duplex (TDD mode where the channel reciprocity is exploited, our schemes turn out to be robust against the mismatch between the uplink and downlink channels. The advantages of our schemes are demonstrated via extensive numerical examples.

  14. Interference-type time lens based on temporal hologram in a loop configuration.

    Science.gov (United States)

    Hu, Xiao; Li, Honggen

    2015-12-10

    An alternative scheme is proposed for implementing a time lens based on the temporal hologram concept. Instead of using edge-pass filtering, this scheme achieves the keeping of only the time-lens (quadratic phase modulation) term of interest through the interference of two modulated component beams. In this scheme, an additional linear frequency component does not have to be added to the electronic drive signal to avoid the overlapping of the target frequency component and its conjugate of the modulated signal. Thus, the proposed hologram-based time lens is not only able to relax the limitation of the bandwidth and sampling rate of the arbitrary waveform generator on the time-bandwidth product and resolution to some extent, but is also capable of processing shorter input pulse signals. These advantages make the proposed interference-type hologram time lens especially suitable for use in a loop configuration, where it can be reused when the signal pulse circulates in the loop. This promises significantly enhanced time-bandwidth product and resolution, and the temporal aperture size can be designed as large as desired theoretically.

  15. Reverse engineering of free-form surface based on the closed-loop theory.

    Science.gov (United States)

    He, Xue Ming; He, Jun Fei; Wu, Mei Ping; Zhang, Rong; Ji, Xiao Gang

    2015-01-01

    To seek better methods of measurement and more accurate model of reconstruction in the field of reverse engineering has been the focus of researchers. Based on this, a new method of adaptive measurement, real-time reconstruction, and online evaluation of free-form surface was presented in this paper. The coordinates and vectors of the prediction points are calculated according to a Bézier curve which is fitted by measured points. Final measured point cloud distribution is in agreement with the geometric characteristics of the free-form surfaces. Fitting the point cloud to a surface model by the nonuniform B-spline method, extracting some check points from the surface models based on grids and a feature on the surface, review the location of these check points on the surface with CMM and evaluate the model, and then update the surface model to meet the accuracy. Integrated measurement, reconstruction, and evaluation, with the closed-loop reverse process, established an accurate model. The results of example show that the measuring points are distributed over the surface according to curvature, and the reconstruction model can be completely expressed with micron level. Meanwhile, measurement, reconstruction and evaluation are integrated in forms of closed-loop reverse system.

  16. Amineborane Based Chemical Hydrogen Storage - Final Report

    International Nuclear Information System (INIS)

    The development of efficient and safe methods for hydrogen storage is a major hurdle that must be overcome to enable the use of hydrogen as an alternative energy carrier. The objectives of this project in the DOE Center of Excellence in Chemical Hydride Storage were both to develop new methods for on-demand, low temperature hydrogen release from chemical hydrides and to design high-conversion off-board methods for chemical hydride regeneration. Because of their reactive protic (N-H) and hydridic (B-H) hydrogens and high hydrogen contents, amineboranes such as ammonia borane, NH3BH3 (AB), 19.6-wt% H2, and ammonia triborane NH3B3H7 (AT), 17.7-wt% H2, were initially identified by the Center as promising, high-capacity chemical hydrogen storage materials with the potential to store and deliver molecular hydrogen through dehydrogenation and hydrolysis reactions. In collaboration with other Center partners, the Penn project focused both on new methods to induce amineborane H2-release and on new strategies for the regeneration the amineborane spent-fuel materials. The Penn approach to improving amineborane H2-release focused on the use of ionic liquids, base additives and metal catalysts to activate AB dehydrogenation and these studies successfully demonstrated that in ionic liquids the AB induction period that had been observed in the solid-state was eliminated and both the rate and extent of AB H2-release were significantly increased. These results have clearly shown that, while improvements are still necessary, many of these systems have the potential to achieve DOE hydrogen-storage goals. The high extent of their H2-release, the tunability of both their H2 materials weight-percents and release rates, and their product control that is attained by either trapping or suppressing unwanted volatile side products, such as borazine, continue to make AB/ionic-liquid based systems attractive candidates for chemical hydrogen storage applications. These studies also demonstrated

  17. Amineborane Based Chemical Hydrogen Storage - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sneddon, Larry G.

    2011-04-21

    The development of efficient and safe methods for hydrogen storage is a major hurdle that must be overcome to enable the use of hydrogen as an alternative energy carrier. The objectives of this project in the DOE Center of Excellence in Chemical Hydride Storage were both to develop new methods for on-demand, low temperature hydrogen release from chemical hydrides and to design high-conversion off-board methods for chemical hydride regeneration. Because of their reactive protic (N-H) and hydridic (B-H) hydrogens and high hydrogen contents, amineboranes such as ammonia borane, NH3BH3 (AB), 19.6-wt% H2, and ammonia triborane NH3B3H7 (AT), 17.7-wt% H2, were initially identified by the Center as promising, high-capacity chemical hydrogen storage materials with the potential to store and deliver molecular hydrogen through dehydrogenation and hydrolysis reactions. In collaboration with other Center partners, the Penn project focused both on new methods to induce amineborane H2-release and on new strategies for the regeneration the amineborane spent-fuel materials. The Penn approach to improving amineborane H2-release focused on the use of ionic liquids, base additives and metal catalysts to activate AB dehydrogenation and these studies successfully demonstrated that in ionic liquids the AB induction period that had been observed in the solid-state was eliminated and both the rate and extent of AB H2-release were significantly increased. These results have clearly shown that, while improvements are still necessary, many of these systems have the potential to achieve DOE hydrogen-storage goals. The high extent of their H2­-release, the tunability of both their H2 materials weight-percents and release rates, and their product control that is attained by either trapping or suppressing unwanted volatile side products, such as borazine, continue to make AB/ionic­-liquid based systems attractive candidates for chemical hydrogen storage applications. These studies also

  18. A Single Loop Vectorization Method Based on Assemble Code%一种基于汇编代码的单重循环向量化方法

    Institute of Scientific and Technical Information of China (English)

    陆洪毅; 戴葵; 王志英

    2003-01-01

    Through loops vectorization in instruction sequence, the vector power provided by hardware can be fully utilized. This paper analyzes the RISC instructton set, and presents a single loop vectorization method that is based on assemble code, it can efficiently detect single loops in instruct sequence and vectorize them.

  19. Integration of in-situ CO2-oxy coal gasification with advanced power generating systems performing in a chemical looping approach of clean combustion

    International Nuclear Information System (INIS)

    Highlights: • Integration of CO2/O2 based UCG, CLC and CCS for clean coal utilization. • Incorporation of CLC system reduces the ASU load of the power plant. • Use of CO enriched UCG gas in Ni based CLC reduces the difficulty of heat balance. • Coupling of the proposed UCG with IGCC and IGST for the efficient power generation. • Demonstration of reduced CCS energy penalty in the advanced coupled system. - Abstract: Underground coal gasification (UCG) is a clean coal technology to utilize deep coal resources effectively. In-situ CO2-oxy coal gasification may eliminate the operational difficulty of the steam gasification process and utilize CO2 (greenhouse gas) effectively. Furthermore, it is necessary to convert the clean gasified energy from the UCG into clean combustion energy for an end-use. In order to achieve efficient clean power production, the present work investigates the thermodynamic feasibility of integration of CO2 based UCG with power generating systems operating in a chemical looping combustion (CLC) of product gas. The use of CO enriched syngas from O2/CO2 based UCG reduces the difficulty of the heat balance between a fuel reactor and an air reactor in a nickel oxygen-carrier based CLC system. Thermodynamic analyses have been made for various routes of power generation systems such as subcritical, supercritical and ultra-supercritical boiler based steam turbines and gas turbines for the UCG integrated system. It is shown, based on mass and energy balance analysis, that the integration of CO2 based UCG with the CLC system reduces the energy penalty of carbon capture and storage (CCS) significantly. A net thermal efficiency of 29.42% is estimated for the CCS incorporated system, which operates in a subcritical condition based steam turbine power plant. Furthermore, it is found that the efficiency of the proposed steam turbine system increases to 35.40% for an ultra-supercritical operating condition. The effect of operating temperature of the

  20. Carbon-Nanotube-Based Chemical Gas Sensor

    Science.gov (United States)

    Kaul, Arunpama B.

    2010-01-01

    Conventional thermal conductivity gauges (e.g. Pirani gauges) lend themselves to applications such as leak detectors, or in gas chromatographs for identifying various gas species. However, these conventional gauges are physically large, operate at high power, and have a slow response time. A single-walled carbon-nanotube (SWNT)-based chemical sensing gauge relies on differences in thermal conductance of the respective gases surrounding the CNT as it is voltage-biased, as a means for chemical identification. Such a sensor provides benefits of significantly reduced size and compactness, fast response time, low-power operation, and inexpensive manufacturing since it can be batch-fabricated using Si integrated-circuit (IC) process technology.

  1. A Loop-Based Apparatus for At-Speed Self-Testing

    Institute of Scientific and Technical Information of China (English)

    LI Xiaowei; Paul Y.S. Cheung

    2001-01-01

    At-speed testing using external tester requires an expensive equip ment, thus built-in self-test (BIST) is an alternative technique due to its ability to perform on-chip at-speed self-testing. The main issue in BIST for at-speed testing is to obtain high delay fault coverage with a low hardware overhead. This pa per presents an improved loop-based BIST scheme, in which a configurable MISR (multiple-input signature register) is used to generate test-pair sequences. The struc ture and operation modes of the BIST scheme are described. The topological proper ties of the state-transition-graph of the proposed BIST scheme are analyzed. Based on it, an approach to design and efficiently implement the proposed BIST scheme is developed. Experimental results on academic benchmark circuits are presented to demonstrate the effectiveness of the proposed BIST scheme as well as the design approach.

  2. Phase-locked loop based on machine surface topography measurement using lensed fibers

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jin-Ho; Lee, ChaBum; Joo, Jae-Young; Lee, Sun-Kyu

    2011-02-01

    We present the phase-locked loop (PLL)-based metrology concept using lensed fibers for on-machine surface topography measurement. The shape of a single-mode fiber at the endface was designed using an ABCD matrix method, and two designed lensed fibers--the ball type and the tapered type--were fabricated, and the performance was evaluated, respectively. As a result, the interferometric fringe was not found in the case of the ball lensed fiber, but the machined surface could be measured by utilization of autofocusing and intensity methods. On the other hand, a very clear Fizeau interferometric fringe was observed in the case of the tapered lensed fiber. Its performance was compared with the results of the capacitance sensor and a commercially available white-light interferometer. We confirmed that PLL-based surface profile measurement using the tapered and ball lensed fibers can be applied for on-machine surface topography measurement applications.

  3. Genetic diversity of native chicken based on analysis of D-Loop mtDNA marker

    Directory of Open Access Journals (Sweden)

    Tike Sartika

    2000-06-01

    Full Text Available Production was carried out using control region/D-loop mtDNA marker. The base population of native chicken was selected from subpopulation at Cianjur, Jatiwangi, Depok, Bogor I, and Bogor 2. Samples from each population was 10 heads and 2 samples Green Jungle Fowl (Gallus various from East Java as out Group samples. Two primers binding conserved tRNA Phenylalanine gene and tRNA Glutamine gene were DNA Heavy stranded HI255 (5'-CATCTTGGCATCTTCAGTGCC-3' and DNA Light stranded Ll6750 (5'-AGGACTACGGCTTGAAAAGC-3' was used to amplify D-Ioop mtDNA chicken. PCR-RFLP methods with 6 restriction enzymes 4 cutter such as, Alul (AG↓CT, Hpall (C↓CGG, Mbol (↓GATC, Rsal (GT↓AC, NlaIII (CATG↓ and HaeIII (GG↓CC were used to detect polymorphism within and between subpopulation. Result of experiment show that mtDNA which was amplified by PCR was 1320 bp, consist of 1227 bp control region/D-loop, 45 bp tRNA Glutamine gene and 48 bp tRNA Phenylalananine gene. PCR product which were digested from 6 endonucleases enzyme show that native chicken within and between population was monomorphic and if its compare with Green Jungle Fowl was polymorphic.

  4. Thermal energy harvesting plasmonic based chemical sensors.

    Science.gov (United States)

    Karker, Nicholas; Dharmalingam, Gnanaprakash; Carpenter, Michael A

    2014-10-28

    Detection of gases such as H2, CO, and NO2 at 500 °C or greater requires materials with thermal stability and reliability. One of the major barriers toward integration of plasmonic-based chemical sensors is the requirement of multiple components such as light sources and spectrometers. In this work, plasmonic sensing results are presented where thermal energy is harvested using lithographically patterned Au nanorods, replacing the need for an external incident light source. Gas sensing results using the harvested thermal energy are in good agreement with sensing experiments, which used an external incident light source. Principal Component Analysis (PCA) was used to reduce the wavelength parameter space from 665 variables down to 4 variables with similar levels of demonstrated selectivity. The combination of a plasmonic-based energy harvesting sensing paradigm with PCA analysis offers a novel path toward simplification and integration of plasmonic-based sensing methods. PMID:25280004

  5. Waveguide-based optical chemical sensor

    Science.gov (United States)

    Grace, Karen M.; Swanson, Basil I.; Honkanen, Seppo

    2007-03-13

    The invention provides an apparatus and method for highly selective and sensitive chemical sensing. Two modes of laser light are transmitted through a waveguide, refracted by a thin film host reagent coating on the waveguide, and analyzed in a phase sensitive detector for changes in effective refractive index. Sensor specificity is based on the particular species selective thin films of host reagents which are attached to the surface of the planar optical waveguide. The thin film of host reagents refracts laser light at different refractive indices according to what species are forming inclusion complexes with the host reagents.

  6. Bending and Twisting the Embryonic Heart: A Computational Model for C-Looping Based on Realistic Geometry

    Directory of Open Access Journals (Sweden)

    Yunfei eShi

    2014-08-01

    Full Text Available The morphogenetic process of cardiac looping transforms the straight heart tube into a curved tube that resembles the shape of the future four-chambered heart. Although great progress has been made in identifying the molecular and genetic factors involved in looping, the physical mechanisms that drive this process have remained poorly understood. Recent work, however, has shed new light on this complicated problem. After briefly reviewing the current state of knowledge, we propose a relatively comprehensive hypothesis for the mechanics of the first phase of looping, termed c-looping, as the straight heart tube deforms into a c-shaped tube. According to this hypothesis, differential hypertrophic growth in the myocardium supplies the main forces that cause the heart tube to bend ventrally, while regional growth and contraction in the omphalomesenteric veins (primitive atria and compressive loads exerted by the splanchnopleuric membrane drive rightward torsion. A computational model based on realistic embryonic heart geometry is used to test this hypothesis. The behavior of the model is in reasonable agreement with available experimental data from control and perturbed embryos, offering support for our hypothesis. The results also suggest, however, that several other mechanisms contribute secondarily to normal looping, and we speculate that these mechanisms play backup roles when looping is perturbed. Finally, some outstanding questions are discussed for future study.

  7. Benchmarking of Phase Locked Loop based Synchronization Techniques for Grid-Connected Inverter Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Hadjidemetriou, Lenos; Blaabjerg, Frede;

    2015-01-01

    , becoming inevitable challenges to the synchronization of the grid-connected renewable energy systems. In order to ensure the quality of the power generation from the renewables, robust and reliable synchronization methods are in demand. Among the prior-art solutions, Phase Locked Loop (PLL) based...... synchronization methods have gained much popularity in grid-connected applications. However, an appropriate selection and thus a proper design of the selected PLL synchronization remain of interest in practice, especially for single-phase systems. Therefore, in this paper, a benchmarking of the main PLL...... synchronization methods for single-phase grid-connected inverter systems in terms of accuracy, dynamic response, harmonic immunity, etc., has been conducted. Experiments on a 1-kW single-phase grid-connected system, suffering from different grid disturbances, are performed for the benchmarking. The experimental...

  8. Chemical Sensors Based on Metal Oxide Nanostructures

    Science.gov (United States)

    Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Mike J.; Liu, Chung-Chiun

    2006-01-01

    This paper is an overview of sensor development based on metal oxide nanostructures. While nanostructures such as nanorods show significan t potential as enabling materials for chemical sensors, a number of s ignificant technical challenges remain. The major issues addressed in this work revolve around the ability to make workable sensors. This paper discusses efforts to address three technical barriers related t o the application of nanostructures into sensor systems: 1) Improving contact of the nanostructured materials with electrodes in a microse nsor structure; 2) Controling nanostructure crystallinity to allow co ntrol of the detection mechanism; and 3) Widening the range of gases that can be detected by using different nanostructured materials. It is concluded that while this work demonstrates useful tools for furt her development, these are just the beginning steps towards realizati on of repeatable, controlled sensor systems using oxide based nanostr uctures.

  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. Operational experience with a system of coupled fluidized beds for chemical looping combustion of solid fuels using ilmenite as oxygen carrier

    International Nuclear Information System (INIS)

    Highlights: • Successful operation of a coupled fluidized bed system for CLC of coal. • Two-stage design worked well, i.e. the 2nd stage has an significant effect on fuel conversion. • Solids circulation rates were determined. • High carbon capture rate (ηCC > 96%), which might be attributed to the very fine coal. - Abstract: A system of coupled fluidized beds for chemical looping combustion of solid fuels was successfully commissioned. The facility has a rated thermal power of 25 kW and consists of a circulating fluidized bed coupled with a two-stage bubbling fluidized bed. The two-stage bubbling fluidized bed is the fuel reactor and the riser of the circulating fluidized bed is the air reactor. In the experiments Australian ilmenite with a particle size in the range of 100–400 μm was used as the oxygen carrier. The solid fuel was lignite dust with more than 70% of the mass having a particle size smaller than 150 μm. The influence of the operational parameters, i.e. reactor temperature, coal feed rate and composition of the fuel reactor feed gas on the operational behaviour of the system was investigated. The two-stage fuel reactor performed well and CO2-concentrations in the dry fuel reactor off-gas of above 90 vol.% were achieved. The reason for the appearance of unconverted combustible gases in the fuel reactor off-gas needs further investigation. Solids circulation rates based on the riser cross-section were determined under hot operating conditions and turned out to be between 56 and 70 kg/m2 s. The carbon slip to the air reactor was small in all tests: only 1.5–6.5 wt.% of the fixed carbon introduced with the coal were oxidized in the air reactor

  11. Experimental Program for the validation of the design of a 150KWth Chemical looping Combustion reactor system with main focus on the reactor flexibility and operability

    OpenAIRE

    Ghorbaniyan, Masoud

    2011-01-01

    Chemical Looping Combustion is one of the most promising way to limit the CO2 release to the atmosphere among the other technologies for Carbon Capture and Storage (CCS). It constitutes an indirect fuel combustion strategy, in which metal oxide is used as oxygen carrier, to transfer oxygen from the combustion air to the fuel, avoiding direct contact between air and fuel. It is basically an unmixed combustion process (fuel and air are never mixed) whose flue gases are mainly CO2 and steam. Thu...

  12. Current control loop design and analysis based on resonant regulators for microgrid applications

    DEFF Research Database (Denmark)

    Federico, de Bosio; Pastorelli, Michelle; de Sousa Ribeiro, Luiz Antonio;

    2015-01-01

    Voltage and current control loops play an important role in the performance of microgrids employing power electronics voltage source inverters. Correct design of feedback loops is essential for the proper operation of these systems. This paper analyzes the influence of state feedback cross-coupling...... in the design of resonant regulators for inner current loops in power converters operating in standalone microgrids. It is also demonstrated that the effect of state feedback cross-coupling degrades the performance of the control loops by increasing the steady-state error. Different resonant regulators...

  13. Multiplexed readout demonstration of a TES-based detector array in a resistance locked loop

    CERN Document Server

    van der Kuur, Jan; Kiviranta, Mikko; Akamatsu, Hiroki; Khosropanah, Pourya; Hartog, Roland den; Suzuki, Toyoaki; Jackson, Brian

    2015-01-01

    TES-based bolometer and microcalorimeter arrays with thousands of pixels are under development for several space-based and ground-based applications. A linear detector response and low levels of cross talk facilitate the calibration of the instruments. In an effort to improve the properties of TES-based detectors, fixing the TES resistance in a resistance-locked loop (RLL) under optical loading has recently been proposed. Earlier theoretical work on this mode of operation has shown that the detector speed, linearity and dynamic range should improve with respect to voltage biased operation. This paper presents an experimental demonstration of multiplexed readout in this mode of operation in a TES-based detector array with noise equivalent power values (NEP) of $3.5\\cdot 10^{-19} $W/$\\sqrt{\\mathrm{Hz}}$. The measured noise and dynamic properties of the detector in the RLL will be compared with the earlier modelling work. Furthermore, the practical implementation routes for future FDM systems for the readout of ...

  14. Active-Flux-Based, V/f-with-Stabilizing-Loops Versus Sensorless Vector Control of IPMSM Drives

    DEFF Research Database (Denmark)

    Moldovan, Ana; Blaabjerg, Frede; Boldea, Ion

    2011-01-01

    . By this control strategy, a fast dynamic speed response, without steady state error and without speed or current regulators, for all AC machines is obtained. The second control method is a sensorless vector control strategy which also has been implemented and tested, just for comparison.......This paper proposes two control methods for Interior Permanent Magnet Synchronous Motor (IPMSM) Drives. The first one is a V/f control with two stabilizing loops: one loop based on active flux balance for voltage magnitude correction and a second, based on speed error, with voltage phase correction...

  15. Sheared-type G(anti).C(syn) base-pair: a unique d(GXC) loop closure motif.

    Science.gov (United States)

    Chin, Ko-Hsin; Chou, Shan-Ho

    2003-05-30

    Stable DNA loop structures closed by a novel G.C base-pair have been determined for the single-residue d(GXC) loops (X=A, T, G or C) in low-salt solution by high-resolution nuclear magnetic resonance (NMR) techniques. The closing G.C base-pair in these loops is not of the canonical Watson-Crick type, but adopts instead a unique sheared-type (trans Watson-Crick/sugar-edge) pairing, like those occurring in the sheared mismatched G.A or A.C base-pair, to draw the two opposite strands together. The cytidine residue in the closing base-pair is transformed into the rare syn domain to form two H-bonds with the guanine base and to prevent the steric clash between the G 2NH(2) and the C H-5 protons. Besides, the sugar pucker of the syn cytidine is still located in the regular C2'-endo domain, unlike the C3'-endo domain adopted for the pyrimidines of the out-of-alternation left-handed Z-DNA structure. The facile formation of the compact d(GXC) loops closed by a unique sheared-type G(anti).C(syn) base-pair demonstrates the great potential of the single-stranded d(GXC) triplet repeats to fold into stable hairpins. PMID:12758081

  16. Double loop control strategy with different time steps based on human characteristics.

    Science.gov (United States)

    Gu, Gwang Min; Lee, Jinoh; Kim, Jung

    2012-01-01

    This paper proposes a cooperative control strategy in consideration of the force sensitivity of human. The strategy consists of two loops: one is the intention estimation loop whose sampling time can be variable in order to investigate the effect of the sampling time; the other is the position control loop with fixed time step. A high sampling rate is not necessary for the intention estimation loop due to the bandwidth of the mechanoreceptors in humans. In addition, the force sensor implemented in the robot is sensitive to the noise induced from the sensor itself and tremor of the human. Multiple experiments were performed with the experimental protocol using various time steps of the intention estimation loop to find the suitable sampling times in physical human robot interaction. The task involves pull-and-push movement with a two-degree-of-freedom robot, and the norm of the interaction force was obtained for each experiment as the measure of the cooperative control performance.

  17. Deep sounding TEM investigation method based on a modified fixed central-loop system

    Science.gov (United States)

    Xue, Guo-qiang; Bai, Chao-ying; Yan, Shu; Greenhalgh, Stewart; Li, Mei-fang; Zhou, Nan-nan

    2012-01-01

    The central-loop TEM technology has been widely used in mineral exploration, engineering and environmental investigations and assorted geologic studies. For easy and efficient working conditions, a square (or rectangular) loop is generally employed instead of a circular one. Any position within the inner one ninth of the central part of the loop is often designated as the central survey location (within which the field is assumed to be uniform), and referred to as a modified central-loop configuration. However, the deduced field parameters at such non-central positions when calculated by a central-loop formula result in decreased accuracy and possibly erroneous interpretation. A large-fixed loop offers the advantage of being able to determine the induced potential at any point inside or outside the loop. In this study we provide the formula for the large-fixed loop and receiver positions within the modified central-loop system and solve the problem. Specifically, we compute the electromagnetic response of any field point by using an electric dipole integration method. The full time-domain apparent resistivity values are then extracted by using an iterative method. Both theoretical modeling and real data examples indicate that such a configuration not only improves the accuracy for the TEM survey, but also enlarges the exploration depth, due to a large loop used in the deployment. The method is used for locating the water enriched areas in coal mines in Yangquan region of Shanxi province and in Bin County of Shaanxi province, China. The interpreted results are tested by later drilling, which confirmed our combined method to be a reliable and efficient method for deep sounding.

  18. Digital self-excited loop based RF control for the superconducting resonators of IUAC Linac

    International Nuclear Information System (INIS)

    Self-excited loop (SEL) is a convenient architecture of an RF control system for setting-up and stabilization of RF field in a superconducting resonator. The existing RF control for the resonators of 97 MHz Quarter Wave Resonators of IUAC Linac is based on SEL implemented in analog domain. In order to take the benefit of the recent advancements in the field of digital technology, a digital SEL based RF control system is being developed for these resonators. In the first phase a prototype system, incorporating RF control of one resonator has been developed. The system is based on sampling the input RF signals directly without resorting to down-conversion. Sampling is carried out at 4/9 of the reference frequency and the subsequent processing is carried out in an FPGA. Tests have been performed under both free running and locked mode of operation. The results are encouraging and a compact system incorporating control of four resonators in a single digital board is under design

  19. Characterization study and five-cycle tests in a fixed-bed reactor of titania-supported nickel oxide as oxygen carriers for the chemical-looping combustion of methane.

    Science.gov (United States)

    Corbella, Beatriz M; de Diego, Luis F; García-Labiano, Francisco; Adánez, Juan; Palaciost, José M

    2005-08-01

    Recent investigations have shown that in the combustion of carbonaceous compounds CO2 and NOx emissions to the atmosphere can be substantially reduced by using a two stage chemical-looping process. In this process, the reduction stage is undertaken in a first reactor in which the framework oxygen of a reducible inorganic oxide is used, instead of the usual atmospheric oxygen, for the combustion of a carbonaceous compound, for instance, methane. The outlet gas from this reactor is mostly composed of CO2 and steam as reaction products and further separation of these two components can be carried out easily by simple condensation of steam. Then, the oxygen carrier found in a reduced state is transported to a second reactor in which carrier regeneration with air takes place at relatively low temperatures, consequently preventing the formation of thermal NOx. Afterward, the regenerated carrier is carried to the first reactor to reinitiate a new cycle and so on for a number of repetitive cycles, while the carrier is able to withstand the severe chemical and thermal stresses involved in every cycle. In this paper, the performance of titania-supported nickel oxides has been investigated in a fixed-bed reactor as oxygen carriers for chemical-looping combustion of methane. Samples with different nickel oxide contents were prepared by successive incipient wet impregnations, and their performance as oxygen carriers was investigated at 900 degrees C and atmospheric pressure in five-cycle fixed-bed reactor tests using pure methane and pure air for the respective reduction and regeneration stages. The evolution of the outlet gas composition in each stage was followed by gas chromatography, and the involved chemical, structural, and textural changes of the carrier in the reactor bed were studied by using different characterization techniques. From the study, it is deduced that the reactivity of these nickel-based oxygen carriers is in the two involved stages and almost independent

  20. Analysis of in-vivo LacR-mediated gene repression based on the mechanics of DNA looping.

    Directory of Open Access Journals (Sweden)

    Yongli Zhang

    Full Text Available Interactions of E. coli lac repressor (LacR with a pair of operator sites on the same DNA molecule can lead to the formation of looped nucleoprotein complexes both in vitro and in vivo. As a major paradigm for loop-mediated gene regulation, parameters such as operator affinity and spacing, repressor concentration, and DNA bending induced by specific or non-specific DNA-binding proteins (e.g., HU, have been examined extensively. However, a complete and rigorous model that integrates all of these aspects in a systematic and quantitative treatment of experimental data has not been available. Applying our recent statistical-mechanical theory for DNA looping, we calculated repression as a function of operator spacing (58-156 bp from first principles and obtained excellent agreement with independent sets of in-vivo data. The results suggest that a linear extended, as opposed to a closed v-shaped, LacR conformation is the dominant form of the tetramer in vivo. Moreover, loop-mediated repression in wild-type E. coli strains is facilitated by decreased DNA rigidity and high levels of flexibility in the LacR tetramer. In contrast, repression data for strains lacking HU gave a near-normal value of the DNA persistence length. These findings underscore the importance of both protein conformation and elasticity in the formation of small DNA loops widely observed in vivo, and demonstrate the utility of quantitatively analyzing gene regulation based on the mechanics of nucleoprotein complexes.

  1. M-H loop tracer based on digital signal processing for low frequency characterization of extremely thin magnetic wires

    Energy Technology Data Exchange (ETDEWEB)

    Butta, M.; Ripka, P. [Department of Measurement, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague 16627 (Czech Republic); Infante, G.; Badini-Confalonieri, G. A.; Vazquez, M. [Instituto de Ciencia de Materiales de Madrid (CSIC), Campus de Cantoblanco, Madrid 28049 (Spain)

    2009-08-15

    A high-sensitivity ac hysteresis loop tracer has been developed to measure the low frequency hysteresis loop of soft magnetic materials. It has been applied successfully to characterize straight pieces of amorphous glass-covered microwires with metallic nucleus down to 1.5 {mu}m thick. Based on the electromagnetic induction law, the proposed design is extremely simple and exploits the capabilities of commercially available data acquisition cards together with digital signal processing in order to achieve high-sensitivity without the need of expensive analog equipment.

  2. Robust PID design based on static H∞ loop-shaping method for steam generator water level control

    International Nuclear Information System (INIS)

    The problem for control of steam generator water level is complex because its complicated shrink and parameters of its model vary with operation conditions. Static H∞ loop shaping is used to design the robust PID controller for the steam generator. Simulation results show that the control efficiency of this scheme is better than that of the other three H∞ loop shaping based methods, and the derived controller has good reference tracking capability, distribution rejection ability and acceptable control performance at different operation points. (authors)

  3. A SEMI-OPEN-LOOP CODING MODE SELECTION ALGORITHM BASED ON EFM AND SELECTED AMR-WB+ FEATURES

    Institute of Scientific and Technical Information of China (English)

    Hong Ying; Zhao Shenghui; Kuang Jingming

    2009-01-01

    To solve the problems of the AMR-WB+ (Extended Adaptive Multi-Rate-WideBand) semi-open-loop coding mode selection algorithm, features for ACELP (Algebraic Code Excited Linear Prediction) and TCX (Transform Coded eXcitation) classification are investigated. 11 classifying features in the AMR-WB+ codec are selected and 2 novel classifying features, i.e., EFM (Energy Flatness Measurement) and stdEFM (standard deviation of EFM), are proposed. Consequently, a novel semi-open-loop mode selection algorithm based on EFM and selected AMR-WB+ features is proposed. The results of classifying test and listening test show that the performance of the novel algorithm is much better than that of the AMR-WB+ semi-open-loop coding mode selection algorithm.

  4. Image restoration of the open-loop adaptive optics retinal imaging system based on optical transfer function analysis

    Science.gov (United States)

    Yu, Lei; Qi, Yue; Li, Dayu; Xia, Mingliang; Xuan, Li

    2013-07-01

    The residual aberrations of the adaptive optics retinal imaging system will decrease the quality of the retinal images. To overcome this obstacle, we found that the optical transfer function (OTF) of the adaptive optics retinal imaging system can be described as the Levy stable distribution. Then a new method is introduced to estimate the OTF of the open-loop adaptive optics system, based on analyzing the residual aberrations of the open-loop adaptive optics system in the residual aberrations measuring mode. At last, the estimated OTF is applied to restore the retinal images of the open-loop adaptive optics retinal imaging system. The contrast and resolution of the restored image is significantly improved with the Laplacian sum (LS) from 0.0785 to 0.1480 and gray mean grads (GMG) from 0.0165 to 0.0306.

  5. Laser-based Online Sliding-window Approach for UAV Loop-closure Detection in Urban Environments

    Directory of Open Access Journals (Sweden)

    Anqing Wang

    2016-04-01

    Full Text Available Online loop-closure detection serves as an essential task for Unmanned Aerial Vehicles (UAVs equipped with laser scanners. Due to the inherent errors in UAVs’ pose estimation, a 3-D reconstruction algorithm is adopted to perform 3-D map building, which establishes probabilistic models of the system according to the assumption of errors. To meet the demand of online loop-closure detection using sequential 2-D laser data, a robust ISW-NDT (incremental sliding-window-based NDT approach is proposed, which compares the appearance similarity between two scans by sliding a window with fixed size. Compared with the conventional 3-D NDT approach, the proposed loop-closure detection algorithm is capable of providing superior performance in large-scale outdoor environments, achieving higher recall rate at 100% precision and ensuring successful online implementation. Experimental results show the validity and robustness of the proposed method.

  6. Wavefront response matrix for closed-loop adaptive optics system based on non-modulation pyramid wavefront sensor

    Science.gov (United States)

    Wang, Jianxin; Bai, Fuzhong; Ning, Yu; Li, Fei; Jiang, Wenhan

    2012-06-01

    Pyramid wavefront sensor (PWFS) is a kind of wavefront sensor with high spatial resolution and high energy utilization. In this paper an adaptive optics system with PWFS as wavefront sensor and liquid-crystal spatial light modulator (LC-SLM) as wavefront corrector is built in the laboratory. The wavefront response matrix is a key element in the close-loop operation. It can be obtained by measuring the real response to given aberrations, which is easily contaminated by noise and influenced by the inherent aberration in the optical system. A kind of analytic solution of response matrix is proposed, with which numerical simulation and experiment are also implemented to verify the performance of closed-loop correction of static aberration based on linear reconstruction theory. Results show that this AO system with the proposed matrix can work steadily in closed-loop operation.

  7. Data base of chemical explosions in Kazakhstan

    Energy Technology Data Exchange (ETDEWEB)

    Demin, V.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Malahova, M.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Martysevich, P.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Mihaylova, N.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Nurmagambetov, A. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Kopnichev, Yu.F. D. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Edomin, V.I. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan)

    1996-12-01

    Within the bounds of this report, the following works were done: (1) Information about explosion quarries, located in Southern, Eastern and Northern Kasakstan was summarized. (2) The general information about seismicity of areas of location of explosion quarries was adduced. (3) The system of observation and seismic apparatus, recording the local earthquakes and quarry explosions at the territory of Kazakstan were described. (4) Data base of quarry explosions, that were carried out in Southern, Eastern and Northern Kazakstan during 1995 and first half of 1996 year was adduced. (5) Upon the data of registration of explosions in Southern Kazakstan the correlative dependences between power class of explosions and summary weight of charge were constructed. (6) Seismic records of quarry explosions were adduced. It is necessary to note, that the collection of data about quarry explosions in Kazakstan in present time is very difficult task. Organizations, that makes these explosions, are always suffering reorganizations and sometimes it is actually impossible to receive all the necessary information. Some quarries are situated in remote, almost inaccessible regions, and within the bounds of supplier financing not the every quarry was in success to visit. So the present data base upon the chemical explosions for 1995 is not full and in further it`s expansion is possible.

  8. 以煤为燃料的化学链燃烧研究进展%Research and Development of Coal-fueled Chemical Looping Combustion

    Institute of Scientific and Technical Information of China (English)

    李振山; 鲍金花; 孙宏明; 徐雷; 蔡宁生

    2014-01-01

    Coal-fueled chemical looping combustion was studied from three aspects. In the aspect of oxygen carriers, the gas-solid reaction of carriers was studied. Multi-crystal Fe with smooth surface was used as the reactant to eliminate the effect of pore structure. The morphology of solid products was observed under a scanning electron microscope. The problem of directly observing the product morphology was solved. A rate equation theory was developed to describe the macroscopic kinetics based on the nucleation and growth of solid product from molecular level. A model of interaction force between active components and inert supports was developed. The method of improving the reactivity of natural limonite by introducing foreign ions was proposed. In the aspect of interaction between coal and oxygen carriers, the effect of volatiles and ash on oxygen carriers was addressed. The match of char gasification rate and reduction rate can be achieved through catalytic gasification. Fragmentation, attrition, and segregation of coal particles caused the incomplete gas conversion in the fuel reactor. In the reactor aspect, a three fluidized beds reactor with dual circulating loops was built. A steady operation of 140h in hot mode was accomplished. The concepts of downer reactor, low temperature CLC, and direct CLC were proposed for converting the un-reacted gases.%从3个方面介绍以煤为燃料的化学链燃烧的研究进展。在载氧体方面,研究载氧体的气固反应特性,采用表面光滑的Fe多晶片作为反应物,借助扫描电镜观测固体产物,剥离了孔隙结构的影响,解决固体产物微观形貌难以直接观察的问题;建立了基于分子尺度固体产物成核与生长的速率方程,从微观分子尺度来描述宏观的动力学行为;建立活性成分与惰性载体间相互作用力模型;提出通过引入外来离子提高天然钛铁矿载氧体反应活性的方法。在煤与载氧体相互作用方面,考

  9. Slice group based multiple description video coding with three motion compensation loops

    OpenAIRE

    Wang, D; Canagarajah, CN; Bull, DR

    2005-01-01

    The paper proposes a novel scheme for a multiple description video coding approach using the slice group coding tool proposed in H.264. Three motion compensation loops, one central and two side loops, are maintained for two descriptions in the encoder. The central encoder is exactly the same as the basic single description encoder, while the side encoders use information from the main encoder to do the motion compensation with an easily controlled amount of redundancy. If there is no loss, th...

  10. 3D-IN LOOP FILTER FOR VIDEO COMPRESSION BASED ON MOTION COMPENSATED TEMPORAL PIXEL TRAJECTORIES

    OpenAIRE

    E. A. Ayele*, S. B. Dhok

    2016-01-01

    For H.264 standardization, the use of a deblocking filter was introduced in order to improve the quality of video compression through blocking artifacts reduction. Subsequently, the in-loop filters such as deblocking filter, sample adaptive offset, and adaptive loop filter are launched for the present HEVC standardization. However, both filters use spatial data from a frame of the video sequence only despite the fact of temporal correlation within frames. Hence, the quality of filtering proce...

  11. Spin Interference in Rectangle Loop Based on Rashba and Dresselhaus Spin-Orbit Interactions

    Institute of Scientific and Technical Information of China (English)

    NI Jia-Ting; LIANG Xiao-Wan; CHEN Bin; T.Koga

    2009-01-01

    We demonstrate the amplitude and spin polarization of AAS oscillation changing with Rashba spin-orbit interaction(SOI)and Dresselhaus SOI.The amplitude and spin polarization of AB oscillation changing with Rashba SOI and Dresselhaus SOI are demonstrated as well.The ideal quasi-one-dimensional square loop does not exist in reality,therefore to match the experiment better we should consider the shape of the rectangle loop in theory.

  12. Analysis of genetic relationship among Indonesian native chicken breeds based on 335 D-loop sequences

    Directory of Open Access Journals (Sweden)

    Sri Sulandari

    2008-12-01

    Full Text Available he Mitochondrial DNA (mtDNA D-loop segment was PCR amplified and subsequently sequenced for a total of 335 individuals from Indonesian native chicken. The individuals were drawn from sixteen populations of native chicken and three individuals of green jungle fowls (Gallus varius. Indonesian native chicken populations were: Pelung Sembawa, PL (n = 18, Pelung Cianjur, PLC (n = 29 and Arab Silver, ARS (n=30, Cemani, CM (n = 32, Gaok, GA (n = 7, Kedu Hitam, KDH (n = 11, Wareng, T & TW (n = 10, Cemani, CMP (n = 2, Kedu, KD (n=26, Kedu Putih, KDP (n = 15, Sentul Jatiwangi, STJ (n = 27, Ayam Kate, KT (n = 29, Ayam Sentul, STC (n = 15, Arab Golden, ARG (n = 26, Ayam Merawang, MR (n = 28, Kedu Putih Jatiwangi, KDPJ (n=6 and Kapas, KPS (n = 21. Green jungle fowls were: two individuals from Flores island (FL5 and FL57 and one individual (BD42 from Sumbawa island. The sequences of the first 530 nucleotides were used for analysis. Eighty two haplotypes were identified from 78 polymorphic sites for the 335 individuals. Seventy nine haplotypes were identified in native chicken from 57 polymorphic sites while three were of jungle fowls. Phylogenetic analysis indicates that Indonesian native chicken can be grouped into five clades (Clade I, II, IIIc, IIId and IV of the previously identified seven clades (Clade I, II, IIIa, IIIb, IIIc, IIId and IV in Asian domestic chicken. Haplotypes CM10 and CM32 fall to a different category while STC12 is also on its own. Interestingly STC12 clusters together with Gallus gallus gallus (GenBank accession No. SULANDARI et al. Analysis of genetic relationship among Indonesian native chicken breeds based on 335 D-loop sequences 296 AB007720. When CM10 (same as CM14, CM32 and STC12 were removed, 77 haplotypes of domestic chicken were identified from 53 polymorphic sites. All the green jungle fowls are clustered to one clade of their own. The clades of domestic chicken are: Clade I which has three haplotypes, Clade II has 52

  13. Tunable multi-wavelength fiber ring laser based on a Hi-Bi fiber loop mirror

    Institute of Scientific and Technical Information of China (English)

    Zhaoying Wang(王肇颖); Zhiyong Hu(胡智勇); Chunfeng Ge(葛春风); Xiaojun Jiang(姜骁骏); Huanmin Bao(包焕民); Dongfang Jia(贾东方); Shichen Li(李世忱)

    2004-01-01

    A novel tunable multi-wavelength fiber ring laser based on semiconductor optical amplifier(SOA)is proposed by using a high-birefringence(Hi-Bi)fiber loop mirror(FLM)as wavelength filter.With this configuration,the wavelength spacing of this laser can be varied by using the different lengths of Hi-Bi fiber.8 wavelengths spacing on 450 GHz are experimentally obtained with more than 25-dB signal-to-noise ratio(SNR)for each channel using 1.28-m Hi-Bi fiber in Hi-Bi FLM.The output power variation between different channels is measured to be less than 5.9 dB.The linewidth of each channel is compressed from 0.347 to 0.186 nm by 1.5-m unpumped erbium-doped fiber(EDF).Meanwhile,17 wavelengths spacing on ITU-gird(100 GHz)are also obtained with 5.9-m Hi-Bi fiber in Hi-Bi FLM.All these channels can be tuned together over 0.4 nm.

  14. Mobile Target Tracking Based on Hybrid Open-Loop Monocular Vision Motion Control Strategy

    Directory of Open Access Journals (Sweden)

    Cao Yuan

    2015-01-01

    Full Text Available This paper proposes a new real-time target tracking method based on the open-loop monocular vision motion control. It uses the particle filter technique to predict the moving target’s position in an image. Due to the properties of the particle filter, the method can effectively master the motion behaviors of the linear and nonlinear. In addition, the method uses the simple mathematical operation to transfer the image information in the mobile target to its real coordinate information. Therefore, it requires few operating resources. Moreover, the method adopts the monocular vision approach, which is a single camera, to achieve its objective by using few hardware resources. Firstly, the method evaluates the next time’s position and size of the target in an image. Later, the real position of the objective corresponding to the obtained information is predicted. At last, the mobile robot should be controlled in the center of the camera’s vision. The paper conducts the tracking test to the L-type and the S-type and compares with the Kalman filtering method. The experimental results show that the method achieves a better tracking effect in the L-shape experiment, and its effect is superior to the Kalman filter technique in the L-type or S-type tracking experiment.

  15. An evaluation of multiple annealing and looping based genome amplification using a synthetic bacterial community

    Institute of Scientific and Technical Information of China (English)

    WANG Yong; GAO Zhaoming; XU Ying; LI Guangyu; HE Lisheng; QIAN Peiyuan

    2016-01-01

    The low biomass in environmental samples is a major challenge for microbial metagenomic studies. The amplification of a genomic DNA was frequently applied to meeting the minimum requirement of the DNA for a high-throughput next-generation-sequencing technology. Using a synthetic bacterial community, the amplification efficiency of the Multiple Annealing and Looping Based Amplification Cycles (MALBAC) kit that is originally developed to amplify the single-cell genomic DNA of mammalian organisms is examined. The DNA template of 10 pg in each reaction of the MALBAC amplification may generate enough DNA for Illumina sequencing. Using 10 pg and 100 pg templates for each reaction set, the MALBAC kit shows a stable and homogeneous amplification as indicated by the highly consistent coverage of the reads from the two amplified samples on the contigs assembled by the original unamplified sample. Although GenomePlex whole genome amplification kit allows one to generate enough DNA using 100 pg of template in each reaction, the minority of the mixed bacterial species is not linearly amplified. For both of the kits, the GC-rich regions of the genomic DNA are not efficiently amplified as suggested by the low coverage of the contigs with the high GC content. The high efficiency of the MALBAC kit is supported for the amplification of environmental microbial DNA samples, and the concerns on its application are also raised to bacterial species with the high GC content.

  16. 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

    ) porosity test. The performance of the prepared materials was first evaluated in a TGA reactor through a CO reduction and subsequent steam oxidation process. Then a complete redox process was conducted in a fixed-bed reactor, where the NiFe2O4 oxygen carrier was first reduced by simulated biomass pyrolysis...... gas (24% H2 + 24% CO + 12% CO2 + N2 balance), then reacted with steam to produce H2, and finally fully oxidized by air. The NiFe2O4 oxygen carrier prepared by the sol gel method showed the best capacity for hydrogen production and the highest recovery degree of lattice oxygen, in agreement with the......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...

  17. Stem-loop oligonucleotide beacons as switches for amplifying-fluorescent-polymer-based biological warfare sensors

    Science.gov (United States)

    Clinkenbeard, Kenneth D.; Ramachandran, Akhilesh; Malayer, Jerry R.; Moon, Joong Ho; Hancock, Lawrence F.

    2003-09-01

    Sensors that are exceptionally sensitive with real-time outputs and minimal consumption of reagents are needed to continuously monitor air and water against bioterrorist incidents. Amplifying fluorescent polymers (AFP) provide exceptionally sensitive real-time reagentless sensor platforms as applied to detection of nitroaromatic explosives. This platform technology has the potential to be adapted to detect biological warfare (BW) agents by covalently attaching the 5" end of stem-loop molecular beacons to AFP as DNA hybridization signal transduction switches. Molecular beacons with loop sequences specific for sequence signatures of a target BW agent are configured with a quencher on the end of the 3" arm of the stem-loop. The AFP is quenched in the absence of target DNA, but upon hybridization with target the stem is melted, the duplex loop extended, and the AFP dequenched. This signal transduction is reversible upon removal of the target sequence with the molecular beacon reforming the stem-loop conformation. Proof-of-concept research has demonstrated that molecular beacons for signature sequences of Francisella tularensis result in correct identification of the presence of this agent in samples, but no false positives were seen with Escherichia coli.

  18. Oxidation and Reduction of Iron-Titanium Oxides in Chemical Looping Combustion: A Phase-Chemical Description; Oxydation et reduction des minerais de fer-titane dans la combustion en boucle chimique

    Energy Technology Data Exchange (ETDEWEB)

    Den Hoed, P. [Anglo Research, 8 Schonland Street, Theta 2091, Johannesburg (South Africa); Luckos, A. [Sasol Technology, Sasolburg (South Africa)

    2011-03-15

    Ilmenite (FeTiO{sub 3}) is being explored as an oxygen carrier in chemical looping processes. Its reduction and oxidation are described by the system Fe-Fe{sub 2}O{sub 3}-TiO{sub 2}-Ti{sub 2}O{sub 3}. The phase diagram at 1 000 C, presented here, offers a useful tool for predicting reactions and their products. We see that Fe{sub 2}TiO{sub 5} (pseudo-brookite) and TiO{sub 2} (rutile) form a stable phase assemblage following the oxidation of FeTiO{sub 3} (ilmenite) in air. The subsequent reduction of Fe{sub 2}TiO{sub 5} at oxygen partial pressures of 10{sup -15.5} atm stabilizes Fe{sub 1.02}Ti{sub 0.98}O{sub 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)

  19. Developing an EEG based On-line Closed-loop Lapse Detection and Mitigation System

    Directory of Open Access Journals (Sweden)

    Yu-Te eWang

    2014-10-01

    Full Text Available In America, sixty percent of adults reported that they have driven a motor vehicle while feeling drowsy, and at least 15-20% of fatal car accidents are fatigue-related. This study translates previous laboratory-oriented neurophysiological research to design, develop, and test an On-line Closed-loop Lapse Detection and Mitigation (OCLDM System featuring a mobile wireless dry-sensor EEG headgear and a cell-phone based real-time EEG processing platform. Eleven subjects participated in an event-related lane-keeping task, in which they were instructed to manipulate a randomly deviated, fixed-speed cruising car on a 4-lane highway. This was simulated in a 1st person view with an 8-screen and 8-projector immersive virtual-realty environment. When the subjects experienced lapses or failed to respond to events during the experiment, auditory feedback was delivered to rectify the performance decrements. However, the arousing auditory signals were not always effective. The EEG spectra exhibited statistically significant differences between effective and ineffective arousing signals, suggesting that EEG spectra could be used as a countermeasure of the efficacy of arousing signals. In this on-line pilot study, the proposed OCLDM System was able to continuously detect EEG signatures of fatigue, deliver arousing feedback to subjects suffering momentary cognitive lapses, and assess the efficacy of the feedback in near real-time to rectify cognitive lapses. The on-line testing results of the OCLDM System validated the efficacy of the arousing signals in improving subjects' response times to the subsequent lane-departure events. This study may lead to a practical on-line lapse detection and mitigation system in real-world environments.

  20. High-quality pulse compression in a novel architecture based on a single-mode fiber cascading a nonlinear optical loop mirror

    Science.gov (United States)

    Xu, Yong-zhao; Song, Jian-xun; Zhang, Geng; Liu, Min-xia; Ling, Dong-xiong

    2016-07-01

    A novel all-fiber low-pedestal pulse compression scheme is proposed and investigated. The scheme is based on an anomalously dispersive single-mode fiber (SMF) cascading a nonlinear optical loop mirror (NOLM) with another anomalously dispersive SMF in the loop. Numerical results show that excellent pulse compression and pedestal reduction can be achieved by using the proposed scheme.

  1. AlkB recognition of a bulky DNA base adduct stabilized by chemical cross-linking

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    E.coli AlkB is a direct DNA/RNA repair protein that oxidatively reverses N1 alkylated purines and N3 alkylated pyrimidines to regular bases.Previous crystal structures have revealed N1-methyl adenine(1-meA) recognition by AlkB and a unique base flipping mechanism,but how the AlkB active site can accommodate bulky base adducts is largely unknown.Employing a previously developed chemical cross-linking technique,we crystallized AlkB with a duplex DNA containing a caged thymine base(cagedT).The structure revealed a flexible hairpin lid and a reorganized substrate recognition loop used by AlkB to accommodate cagedT.These observations demonstrate,at the molecular level,how bulky DNA adducts may be recognized and processed by AlkB.

  2. Development of GaN-based micro chemical sensor nodes

    Science.gov (United States)

    Son, Kyung-ah; Prokopuk, Nicholas; George, Thomas; Moon, Jeong S.

    2005-01-01

    Sensors based on III-N technology are gaining significant interest due to their potential for monolithic integration of RF transceivers and light sources and the capability of high temperature operations. We are developing a GaN-based micro chemical sensor node for remote detection of chemical toxins, and present electrical responses of AlGaN/GaN HEMT (High Electron Mobility Transistor) sensors to chemical toxins as well as other common gases.

  3. Recurrent-neural-network-based identification of a cascade hydraulic actuator for closed-loop automotive power transmission control

    International Nuclear Information System (INIS)

    By virtue of its ease of operation compared with its conventional manual counterpart, automatic transmissions are commonly used as automotive power transmission control system in today's passenger cars. In accordance with this trend, research efforts on closed-loop automatic transmission controls have been extensively carried out to improve ride quality and fuel economy. State-of-the-art power transmission control algorithms may have limitations in performance because they rely on the steady-state characteristics of the hydraulic actuator rather than fully exploit its dynamic characteristics. Since the ultimate viability of closed-loop power transmission control is dominated by precise pressure control at the level of hydraulic actuator, closed-loop control can potentially attain superior efficacy in case the hydraulic actuator can be easily incorporated into model-based observer/controller design. In this paper, we propose to use a recurrent neural network (RNN) to establish a nonlinear empirical model of a cascade hydraulic actuator in a passenger car automatic transmission, which has potential to be easily incorporated in designing observers and controllers. Experimental analysis is performed to grasp key system characteristics, based on which a nonlinear system identification procedure is carried out. Extensive experimental validation of the established model suggests that it has superb one-step-ahead prediction capability over appropriate frequency range, making it an attractive approach for model-based observer/controller design applications in automotive systems

  4. Recurrent-neural-network-based identification of a cascade hydraulic actuator for closed-loop automotive power transmission control

    Energy Technology Data Exchange (ETDEWEB)

    You, Seung Han [Hyundai Motor Company, Seoul (Korea, Republic of); Hahn, Jin Oh [University of Alberta, Edmonton (Canada)

    2012-05-15

    By virtue of its ease of operation compared with its conventional manual counterpart, automatic transmissions are commonly used as automotive power transmission control system in today's passenger cars. In accordance with this trend, research efforts on closed-loop automatic transmission controls have been extensively carried out to improve ride quality and fuel economy. State-of-the-art power transmission control algorithms may have limitations in performance because they rely on the steady-state characteristics of the hydraulic actuator rather than fully exploit its dynamic characteristics. Since the ultimate viability of closed-loop power transmission control is dominated by precise pressure control at the level of hydraulic actuator, closed-loop control can potentially attain superior efficacy in case the hydraulic actuator can be easily incorporated into model-based observer/controller design. In this paper, we propose to use a recurrent neural network (RNN) to establish a nonlinear empirical model of a cascade hydraulic actuator in a passenger car automatic transmission, which has potential to be easily incorporated in designing observers and controllers. Experimental analysis is performed to grasp key system characteristics, based on which a nonlinear system identification procedure is carried out. Extensive experimental validation of the established model suggests that it has superb one-step-ahead prediction capability over appropriate frequency range, making it an attractive approach for model-based observer/controller design applications in automotive systems.

  5. What Controls DNA Looping?

    Directory of Open Access Journals (Sweden)

    Pamela J. Perez

    2014-08-01

    Full Text Available The looping of DNA provides a means of communication between sequentially distant genomic sites that operate in tandem to express, copy, and repair the information encoded in the DNA base sequence. The short loops implicated in the expression of bacterial genes suggest that molecular factors other than the naturally stiff double helix are involved in bringing the interacting sites into close spatial proximity. New computational techniques that take direct account of the three-dimensional structures and fluctuations of protein and DNA allow us to examine the likely means of enhancing such communication. Here, we describe the application of these approaches to the looping of a 92 base-pair DNA segment between the headpieces of the tetrameric Escherichia coli Lac repressor protein. The distortions of the double helix induced by a second protein—the nonspecific nucleoid protein HU—increase the computed likelihood of looping by several orders of magnitude over that of DNA alone. Large-scale deformations of the repressor, sequence-dependent features in the DNA loop, and deformability of the DNA operators also enhance looping, although to lesser degrees. The correspondence between the predicted looping propensities and the ease of looping derived from gene-expression and single-molecule measurements lends credence to the derived structural picture.

  6. Dual-rate-loop control based on disturbance observer of angular acceleration for a three-axis aerial inertially stabilized platform.

    Science.gov (United States)

    Zhou, Xiangyang; Jia, Yuan; Zhao, Qiang; Cai, Tongtong

    2016-07-01

    This paper presents a dual-rate-loop control method based on disturbance observer (DOB) of angular acceleration for a three-axis ISP for aerial remote sensing applications, by which the control accuracy and stabilization of ISP are improved obviously. In stabilization loop of ISP, a dual-rate-loop strategy is designed through constituting inner rate loop and the outer rate loop, by which the capability of disturbance rejection is advanced. Further, a DOB-based on angular acceleration is proposed to attenuate the influences of the main disturbances on stabilization accuracy. Particularly, an information fusion method is suggested to obtain accurate angular acceleration in DOB design, which is the key for the disturbance compensation. The proposed methods are theoretically analyzed and experimentally validated to illustrate the effectiveness. PMID:27016450

  7. An optic fiber sensor for multiple gases based on fiber loop ring-down spectroscopy and microring resonator arrays

    Science.gov (United States)

    Zhang, Xin; Jian, Jia-wen; Zheng, Yan-gong; Jin, Han; Zou, Jie

    2016-07-01

    A high-sensitivity sensor for multiple gases based on microring array filter and fiber loop ring-down spectroscopy system is proposed and demonstrated. The parameters of the resonators are designed so that the filtered signal from a broadband light source can be tuned with an absorption spectral line of gas. Therefore, through adding microring resonators horizontally and vertically, the number of target gases and filter range are increased. In this research, in the broad spectral range of about 0.9 μm, only the absorption spectral lines of target gases are filtered. The simulation results show that three target gases, CH4, CO2 and HF, can be simultaneously detected by the sensing system. Owing to the fiber loop ring-down spectroscopy, the whole system is optimized in mini-size and sensitivity, and we can choose different sensing methods to enhance the measurement accuracy for high and low concentration conditions.

  8. Numerical Simulation of Self-Pumped Phase Conjugate Plane-Curve Loop Mirror Based on Photorefractive Nonlinearity

    Institute of Scientific and Technical Information of China (English)

    Mehran Vahdani Moghaddam; Zeynab Chenari; Hamid Latifi; Vladimir Vladimirovich Shuvalov; Konestantin Valentinovich Rudenko

    2008-01-01

    @@ We deal with computer simulation of a transient process in a self-pumped phase conjugate plane-curve loop mirror based on BaTiO3. In optimal circumstances the nonlinear reflectivity and fidelity of such a mirror respectively achieve 0.80-0.90 and 0.95-0.98. The generation of conjugate wave-front occurs due to scattering from the dynamic hologram which is produced in the region of self-intersection of forward and backward beams. In such a model the scenario of passing to unstable generation regimes is similar to the self-pumped phase conjugate plane-plane loop mirror and substantially differs from a single-crystal double phase conjugate mirror.

  9. Study on the Complexity of Closed-loop Supply Chain Based on Price Difference between New and Remanufactured Products

    Directory of Open Access Journals (Sweden)

    Bin Chen

    2013-12-01

    Full Text Available This study studied a more realistic closed-loop supply chain model, which is based on price difference between new and remanufactured products and it contains manufacturers, two recyclers and customers. In this model, assumed that new and remanufactured products have price difference, first we build a decision-making dynamic system model of the manufacturers, two recyclers and customers and then analyze the possibility of the existence of the system equilibrium points and their stability. Through numerical simulation, we use bifurcation diagram, Maximum Lyapunov index variation diagram and chaos attractor to estimate the complexity and chaos of the system comprehensively, observe the profit trends of the manufacturers and recyclers when system change from stability to chaos and analyze the system initial value sensitivity. The conclusion of the numerical simulation has a lot of guidance and reference value to the decision-makers in a closed-loop supply chain.

  10. A Novel Strategy for Thermostability Improvement of Trypsin Based on N-Glycosylation within the Ω-Loop Region.

    Science.gov (United States)

    Guo, Chao; Liu, Ye; Yu, Haoran; Du, Kun; Gan, Yiru; Huang, He

    2016-07-28

    The Ω-loop is a nonregular and flexible structure that plays an important role in molecular recognition, protein folding, and thermostability. In the present study, molecular dynamics simulation was carried out to assess the molecular stability and flexibility profile of the porcine trypsin structures. Two Ω-Loops (fragment 57-67 and fragment 78-91) were confirmed to represent the flexible region. Subsequently, glycosylation site-directed mutations (A73S, N84S, and R104S) were introduced within the Ω-loop region and its wing chain based on its potential N-glycosylation sites (Asn-Xaa-Ser/Thr consensus sequences) and structure information to improve the thermostability of trypsin. The result demonstrated that the halflife of the N84S mutant at 50°C increased by 177.89 min when compared with that of the wildtype enzyme. Furthermore, the significant increase in the thermal stability of the N84S mutant has also been proven by an increase in the Tm values determined by circular dichroism. Additionally, the optimum temperatures of the wild-type enzyme and the N84S mutant were 75°C and 80°C, respectively. In conclusion, we obtained the thermostability-improved enzyme N84S mutant, and the strategy used to design this mutant based on its structural information and N-linked glycosylation modification could be applied to engineer other enzymes to meet the needs of the biotechnological industry. PMID:27012235

  11. A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop

    Science.gov (United States)

    Reyes, Mauricio; Monzón-Hernández, David; Martínez-Ríos, Alejandro; Silvestre, Enrique; Díez, Antonio; Cruz, José Luis; Andrés, Miguel V.

    2013-01-01

    We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10−4 and a short range resolution of 2 × 10−5 for water solutions. PMID:23979478

  12. A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop

    Directory of Open Access Journals (Sweden)

    José Luis Cruz

    2013-08-01

    Full Text Available We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10−4 and a short range resolution of 2 × 10−5 for water solutions.

  13. Ultrafast Phase Comparator for Phase-Locked Loop-Based Optoelectronic Clock Recovery Systems

    DEFF Research Database (Denmark)

    Gomez-Agis, F.; Oxenløwe, Leif Katsuo; Kurimura, S.;

    2009-01-01

    The authors report on a novel application of a chi((2)) nonlinear optical device as an ultrafast phase comparator, an essential element that allows an optoelectronic phase-locked loop to perform clock recovery of ultrahigh-speed optical time-division multiplexed (OTDM) signals. Particular interes...... is devoted to a quasi-phase-matching adhered-ridge-waveguide periodically poled lithium niobate (PPLN) device, which shows a sufficient high temporal resolution to resolve a 640 Gbits OTDM signal.......The authors report on a novel application of a chi((2)) nonlinear optical device as an ultrafast phase comparator, an essential element that allows an optoelectronic phase-locked loop to perform clock recovery of ultrahigh-speed optical time-division multiplexed (OTDM) signals. Particular interest...

  14. Analysis of genetic relationship among Indonesian native chicken breeds based on 335 D-loop sequences

    OpenAIRE

    Sri Sulandari; M Syamsul Arifin Zein; Tike Sartika

    2008-01-01

    he Mitochondrial DNA (mtDNA) D-loop segment was PCR amplified and subsequently sequenced for a total of 335 individuals from Indonesian native chicken. The individuals were drawn from sixteen populations of native chicken and three individuals of green jungle fowls (Gallus varius). Indonesian native chicken populations were: Pelung Sembawa, PL (n = 18), Pelung Cianjur, PLC (n = 29) and Arab Silver, ARS (n=30), Cemani, CM (n = 32), Gaok, GA (n = 7), Kedu Hitam, KDH (n = 11), Wareng, T & TW (n ...

  15. Function Projective Synchronization of Fractional-Order Hyperchaotic System Based on Open-Plus-Closed-Looping

    Institute of Scientific and Technical Information of China (English)

    WANG Xing-Yuan; LIU Rong; ZHANG Na

    2011-01-01

    The purpose of this paper is to analyze the dynamic behavior of fractional-order four-order hyperchaotic Lii system, and use the Open-Plus-Closed-Looping (OPCL) coupling method to construct the system's corresponding response system, and then implement function projective synchronization (FPS) of fractional-order drive-response system with system parameters perturbation or not. Finally, the numerical simulations verify the effectiveness and robustness of this scheme.

  16. Protein Structure Prediction: Knowledge-based Approaches for Loop Prediction and Model Quality Assessment

    OpenAIRE

    Benkert, Pascal

    2007-01-01

    Knowledge of the three-dimensional structure of proteins is of vital importance for understanding their function and for the rational development of new drugs. Homology modelling is currently the most successful method for the prediction of the structure of a protein from its sequence. A structural model is thereby built by incorporating information from experimentally solved proteins showing an evolutionary relationship to the target protein. The accurate prediction of loop regions which fre...

  17. GENETIC DIVERSITY OF KEJOBONG GOAT BASED ON MITOCHONDRIAL DNA D-LOOP SEQUENCE

    Directory of Open Access Journals (Sweden)

    M. F. Harlistyo

    2015-09-01

    Full Text Available This study was aimed to find out the diversity of mtDNA D-loop at Kejobong goat. The completemtDNA D-loop sequence of 12 goat blood samples were analyzed from 4 different location inPurbalingga Regency, Central Java province, sub-districts Kejobong, Pangadegan, Bukateja, andKaligondang. The mtDNA D-loop was extracted from blood sample. DNA obtained were amplified byPCR (Polymerase Chain Reaction method using primers (5’-tcactatcagcacccaaagc-3’ as forward and(5’-ggcattttcagtgccttgct-3’ as reverse and subsequently sequenced. After nucleotide sequencing analysisconducted, 548 bp along was obtained. Nucleotides were then aligned with Capra hircus (GenBankAccess No.: KF952601.1 and apparently there were 11 different sites on the segment of mtDNA Dloop.Five sites could be used as a specific marker to distinguish between the Capra hircus andKejobong goat, namely at the site of 317 (A-G, 403 (T-C, 434 (T-C, 537 (C-T, and 553 (A-G.Nucleotide sequence analysis also contained seven different haplotypes. It was concluded that thedistribution of the different sites showed different haplotype patterns in Kejobong goat.

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

    OpenAIRE

    Słowiński, Grzegorz; Smoliński, Adam

    2016-01-01

    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, of...

  19. EXTENDING THE KNOWLEDGE BASE OF CHEMICAL ENGINEERING

    Institute of Scientific and Technical Information of China (English)

    Mooson Kwauk

    2005-01-01

    The obvious current reversion to micro-scale investigations in basic chemical engineering, combined with the need, of a quite different nature, in the rapid growth of high added-value and small-lot functional materials, have been pointing to an area not yet sufficiently covered by the unit operations, transport phenomena and chemical reaction engineering. Although it is difficult to define accurately this area, a cursory scan of the activities already in progress has revealed a few common attributes: multi-phased (structured), multi-scaled, multi-disciplined, nonlinear, needs for resolution to reductionism-solvable subsystems, and pervasive in the process industry. From these activities, the present paper drafts a tentative scheme for studying the related problems: first to dissect a problem into various scales - spatial, temporal or otherwise as best suits the case in hand- in order to identify pertinent parameters which are then organized into model formulations. Together with inter-scale model formulations, a zoom-in/zoom-out process is carried out between the scales, by trial-and-error and through reasoning, to arrive at a global formulation of a quantitative solution, in order to derive, eventually, the general from the particular.

  20. A Real-Time and Closed-Loop Control Algorithm for Cascaded Multilevel Inverter Based on Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Libing Wang

    2014-01-01

    Full Text Available In order to control the cascaded H-bridges (CHB converter with staircase modulation strategy in a real-time manner, a real-time and closed-loop control algorithm based on artificial neural network (ANN for three-phase CHB converter is proposed in this paper. It costs little computation time and memory. It has two steps. In the first step, hierarchical particle swarm optimizer with time-varying acceleration coefficient (HPSO-TVAC algorithm is employed to minimize the total harmonic distortion (THD and generate the optimal switching angles offline. In the second step, part of optimal switching angles are used to train an ANN and the well-designed ANN can generate optimal switching angles in a real-time manner. Compared with previous real-time algorithm, the proposed algorithm is suitable for a wider range of modulation index and results in a smaller THD and a lower calculation time. Furthermore, the well-designed ANN is embedded into a closed-loop control algorithm for CHB converter with variable direct voltage (DC sources. Simulation results demonstrate that the proposed closed-loop control algorithm is able to quickly stabilize load voltage and minimize the line current’s THD (<5% when subjecting the DC sources disturbance or load disturbance. In real design stage, a switching angle pulse generation scheme is proposed and experiment results verify its correctness.

  1. A decision analytic approach to exposure-based chemical prioritization.

    Directory of Open Access Journals (Sweden)

    Jade Mitchell

    Full Text Available The manufacture of novel synthetic chemicals has increased in volume and variety, but often the environmental and health risks are not fully understood in terms of toxicity and, in particular, exposure. While efforts to assess risks have generally been effective when sufficient data are available, the hazard and exposure data necessary to assess risks adequately are unavailable for the vast majority of chemicals in commerce. The US Environmental Protection Agency has initiated the ExpoCast Program to develop tools for rapid chemical evaluation based on potential for exposure. In this context, a model is presented in which chemicals are evaluated based on inherent chemical properties and behaviorally-based usage characteristics over the chemical's life cycle. These criteria are assessed and integrated within a decision analytic framework, facilitating rapid assessment and prioritization for future targeted testing and systems modeling. A case study outlines the prioritization process using 51 chemicals. The results show a preliminary relative ranking of chemicals based on exposure potential. The strength of this approach is the ability to integrate relevant statistical and mechanistic data with expert judgment, allowing for an initial tier assessment that can further inform targeted testing and risk management strategies.

  2. Construction of a Linux based chemical and biological information system.

    Science.gov (United States)

    Molnár, László; Vágó, István; Fehér, András

    2003-01-01

    A chemical and biological information system with a Web-based easy-to-use interface and corresponding databases has been developed. The constructed system incorporates all chemical, numerical and textual data related to the chemical compounds, including numerical biological screen results. Users can search the database by traditional textual/numerical and/or substructure or similarity queries through the web interface. To build our chemical database management system, we utilized existing IT components such as ORACLE or Tripos SYBYL for database management and Zope application server for the web interface. We chose Linux as the main platform, however, almost every component can be used under various operating systems.

  3. Investigation on an evanescent wave fiber-optic absorption sensor based on fiber loop cavity ring-down spectroscopy

    Science.gov (United States)

    Jiang, Meng; Zhang, Weigang; Zhang, Qi; Liu, Yaping; Liu, Bo

    2010-01-01

    An improved ring-down measurement principle for optical waveguides is presented. Fiber loop ring-down spectroscopy allows for measurement of minute optical losses in high-finesse fiber-optic cavities and immunity to the fluctuation of laser source. The evanescent wave absorption losses dependent on the absorption and the refractive index of ambient solution have been theoretically analyzed. The complex refractive index is introduced into our model and extinction coefficient can be calculated accurately through finite element analysis by setting the boundaries of the fiber and the ambient conditions. Using this method, the refractive index of environment can be taken into consideration. Our principle is validated by the highly-sensitive measurement of evanescent wave absorption loss. By chemically processing the surface of sensing segment along an extending ring-down cavity, the concentration of small volume Diethyl Sulphoxide solution where the etched fiber immersed into has been successfully measured and discussed.

  4. Chemical-potential-based Lattice Boltzmann Method for Nonideal Fluids

    CERN Document Server

    Wen, Binghai; He, Bing; Zhang, Chaoying; Fang, Haiping

    2016-01-01

    Chemical potential is an effective way to drive phase transition or express wettability. In this letter, we present a chemical-potential-based lattice Boltzmann model to simulate multiphase flows. The nonideal force is directly evaluated by a chemical potential. The model theoretically satisfies thermodynamics and Galilean invariance. The computational efficiency is improved owing to avoiding the calculation of pressure tensor. We have derived several chemical potentials of the popular equations of state from the free-energy density function. An effective chemical-potential boundary condition is implemented to investigate the wettability of a solid surface. Remarkably, the numerical results show that the contact angle can be linearly tuned by the surface chemical potential.

  5. Loop Heat Pipes and Capillary Pumped Loops: An Applications Perspective

    Science.gov (United States)

    Butler, Dan; Ku, Jentung; Swanson, Theodore; Obenschain, Arthur F. (Technical Monitor)

    2001-01-01

    Capillary pumped loops (CPLS) and loop heat pipes (LHPS) are versatile two-phase heat transfer devices which have recently gained increasing acceptance in space applications. Both systems work based on the same principles and have very similar designs. Nevertheless, some differences exist in the construction of the evaporator and the hydro-accumulator, and these differences lead to very distinct operating characteristics for each loop. This paper presents comparisons of the two loops from an applications perspective, and addresses their impact on spacecraft design, integration, and test. Some technical challenges and issues for both loops are also addressed.

  6. Scenario-based, closed-loop model predictive control with application to emergency vehicle scheduling

    Science.gov (United States)

    Goodwin, Graham. C.; Medioli, Adrian. M.

    2013-08-01

    Model predictive control has been a major success story in process control. More recently, the methodology has been used in other contexts, including automotive engine control, power electronics and telecommunications. Most applications focus on set-point tracking and use single-sequence optimisation. Here we consider an alternative class of problems motivated by the scheduling of emergency vehicles. Here disturbances are the dominant feature. We develop a novel closed-loop model predictive control strategy aimed at this class of problems. We motivate, and illustrate, the ideas via the problem of fluid deployment of ambulance resources.

  7. Vehicle counting system using optimized virtual loop method based on Real Time video

    Directory of Open Access Journals (Sweden)

    Asst.Prof M.Jyothirmai

    2014-03-01

    Full Text Available This paper describes a computer vision system to detect and count moving vehicles on roads. The system uses a real-time traffic video surveillance camera mounted over roads and computes the total number of vehicles which passed the road. Moving vehicle image is extracted using „double difference image „algorithm and counting is accomplished by tracking vehicle movements within a tracking zone, called virtual loop. The system was tested on a video surveillance record file of a road that has a medium-level traffic volume.

  8. Moving Average Filter-Based Phase-Locked Loops: Performance Analysis and Design Guidelines

    DEFF Research Database (Denmark)

    Golestan, Saeed; Ramezani, Malek; Guerrero, Josep M.;

    2014-01-01

    The phase locked-loops (PLLs) are probably the most widely used synchronization technique in grid-connected applications. The main challenge associated with the PLLs is how to precisely and fast estimate the phase and frequency when the grid voltage is unbalanced and/or distorted. To overcome...... this challenge, incorporating moving average filter(s) (MAF) into the PLL structure has been proposed in some recent literature. A MAF is a linear-phase finite impulse response filter which can act as an ideal low-pass filter, if certain conditions hold. The main aim of this paper is to present the control...

  9. Collier: a fortran-based Complex One-Loop LIbrary in Extended Regularizations

    CERN Document Server

    Denner, Ansgar; Hofer, Lars

    2016-01-01

    We present the library Collier for the numerical evaluation of one-loop scalar and tensor integrals in perturbative relativistic quantum field theories. The code provides numerical results for arbitrary tensor and scalar integrals for scattering processes in general quantum field theories. For tensor integrals either the coefficients in a covariant decomposition or the tensor components themselves are provided. Collier supports complex masses, which are needed in calculations involving unstable particles. Ultraviolet and infrared singularities are treated in dimensional regularization. For soft and collinear singularities mass regularization is available as an alternative.

  10. Chemical-looping gasification of biomass in a 10k Wth interconnected fluidized bed reactor using Fe2 O3/Al2 O3 oxygen carrier

    Institute of Scientific and Technical Information of China (English)

    HUSEYIN Sozen; WEI Guo-qiang; LI Hai-bin; HE Fang; HUANG Zhen

    2014-01-01

    The aim of this research is to design and operate a 10 kW hot chemical-looping gasification ( CLG) unit using Fe2 O3/Al2 O3 as an oxygen carrier and saw dust as a fuel. The effect of the operation temperature on gas composition in the air reactor and the fuel reactor, and the carbon conversion of biomass to CO2 and CO in the fuel reactor have been experimentally studied. A total 60 h run has been obtained with the same batch of oxygen carrier of iron oxide supported with alumina. The results show that CO and H2 concentrations are increased with increasing temperature in the fuel reactor. It is also found that with increasing fuel reactor temperature, both the amount of residual char in the fuel reactor and CO2 concentration of the exit gas from the air reactor are degreased. Carbon conversion rate and gasification efficiency are increased by increasing temperature and H2 production at 870 ℃reaches the highest rate. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET-surface area tests have been used to characterize fresh and reacted oxygen carrier particles. The results display that the oxygen carrier activity is not declined and the specific surface area of the oxygen carrier particles is not decreased significantly.

  11. Chemical Mixture Risk Assessment Additivity-Based Approaches

    Science.gov (United States)

    Powerpoint presentation includes additivity-based chemical mixture risk assessment methods. Basic concepts, theory and example calculations are included. Several slides discuss the use of "common adverse outcomes" in analyzing phthalate mixtures.

  12. A high-resolution time interpolator based on a delay locked loop and an RC delay line

    CERN Document Server

    Mota, M

    1999-01-01

    An architecture for a time interpolation circuit with an rms error of ~25 ps has been developed in a 0.7- mu m CMOS technology. It is based on a delay locked loop (DLL) driven by a 160-MHz reference clock and a passive RC delay line controlled by an autocalibration circuit. Start-up calibration of the RC delay line is performed using code density tests (CDT). The very small temperature/voltage dependence of R and C parameters and the self calibrating DLL results in a low- power, high-resolution time interpolation circuit in a standard digital CMOS technology. (11 refs).

  13. H∞ loop shaping based robust PID controller design and its application for water level control of steam generator

    International Nuclear Information System (INIS)

    A robust PID controller design method was proposed, which was based on PID structured weight function optimization method with linear matrix inequality techniques. By combining static H∞ loop shaping controller synthesis, a robust systematic PID iterative optimization method was given. A PID main controller of steam generator water level control system was designed by using this method. Simulation results show that the control system designed by the given method is of good robust stability and robust performance, and its synthetic control quality is better than the method of full order weight optimization (or PID structured weight optimization mentioned by this paper) combined with normal H∞ controller synthesis. (authors)

  14. Photonic multi-shape UWB pulse generation using a semiconductor optical amplifier-based nonlinear optical loop mirror

    Institute of Scientific and Technical Information of China (English)

    Luo Bo-Wen; Dong Jian-Ji; Yu Yuan; Yang Ting; Zhang Xin-Liang

    2013-01-01

    We propose and demonstrate a scheme to implement photonic multi-shape ultra-wideband (UWB) signal generation using a semiconductor optical amplifier (SOA) based nonlinear optical loop mirror (NOLM).By employing the cross phase modulation (XPM) effect,cross gain modulation (XGM),or both,multi-shape UWB waveforms are generated including monocycle,doublet,triplet,and quadruplet pulses.Both the shapes and polarities of the generated pulses are flexible to adjust,which may be very useful in UWB pulse shape modulation and pulse polarity modulation.

  15. All-optical wavelength conversion of short pulses and NRZ signals based on a nonlinear optical loop mirror

    DEFF Research Database (Denmark)

    Yu, Jianjun; Zheng, Xueyan; Peucheret, Christophe;

    2000-01-01

    Wavelength conversion of short pulses at 10 GHz based on a nonlinear optical loop mirror (NOLM) is experimentally and numerically investigated for the case of small group velocity dispersion and walkoff between the control pulses and continuous lightwaves. Experimental and numerical simulation...... results show that the pulsewidths of the converted signals at different wavelengths are almost the same, and the pulsewidths are compressed when the peak power of the control pulse is smaller than a certain value. An RZ optical source containing eight wavelengths having a high sidemode suppression ratio...

  16. Multi-wavelength fiber laser based on broadband fiber grating and HiBi fiber loop mirror

    Institute of Scientific and Technical Information of China (English)

    JIN Yan-li; LIU Yan-ge; LIU Jian-guo; LI Yan; YUAN Shu-zhong; DONG Xiao-yi

    2007-01-01

    A fiber laser based on broadband C-band fiber grating (CFG) and high birefringence (HiBi) fiber loop mirror (FLM) is demonstrated,which uses the comb-like reflection performance of the HiBi FLM. Under different polarization states,different output lasers are gained by choosing the polarization states of the light in the cavity using the polarization controller.By this method,a single wavelength or dual wavelength laser beam can be output,and multi-wavelength oscillates can be achieved.

  17. A Compiling Framework Based on Uniform Partitioning Schemes for Parallel Loops%基于规范划分集的并行循环编译框架

    Institute of Scientific and Technical Information of China (English)

    黄其军; 丁阳; 余华山; 丁文魁; 许卓群

    2002-01-01

    Compilation of parallel loops is one of the most important parts in parallel compilation and optimization. This paper mainly discusses the key techniques during the compilation implementation of parallel loops, based on the uniform partition schemes. It includes techniques in local array index generating, loop space reconstructing, communication detecting and organizing and data dependence disposing. The efficiency of this implementation has been proved by lots of experiments. The p_HPF compiler which adopts this compiling framework can obtain good speedups and efficiencies. The compiler has been applied in many fields, particularly the field of petroleum exploration.

  18. A Platform for Closing the Open Data Feedback Loop Based on Web2.0 Functionality

    Directory of Open Access Journals (Sweden)

    Charalampos Alexopoulos

    2014-11-01

    Full Text Available One essential element of open data ecosystems concerns their development through feedback loops, discussions and dynamic supplier and user interactions. These user-centric features communicate the users’ needs to the open data community as well to the public sector bodies responsible for data publication. Addressing these needs by the corresponding public sector bodies or even by utilising the power of the community as ENGAGE supports will actually accelerate innovation. However, these elements appear barely to be part of existing open data practices. We conducted a survey which showed that most professional open data users did not know at least one open data infrastructure that enabled five specific types of discussion and feedback mechanisms. The survey showed that much can still be done to improve feedback and discussion on open data infrastructures. In this paper we discuss an open data platform which has started to contribute to filling this gap and present a usage scenario explaining the sequence of the underlined functionality. The discussed ENGAGE open data infrastructure combines functionalities to close the feedback loop and to return information to public authorities for better open data use and publication as well as establishing communication channels between stakeholders. This may effectively lead to the stimulation and facilitation of value generation from open data, as such functionality position the user at the centre of the open data publication process.

  19. Closed Loop Interactions between Spiking Neural Network and Robotic Simulators Based on MUSIC and ROS

    Science.gov (United States)

    Weidel, Philipp; Djurfeldt, Mikael; Duarte, Renato C.; Morrison, Abigail

    2016-01-01

    In order to properly assess the function and computational properties of simulated neural systems, it is necessary to account for the nature of the stimuli that drive the system. However, providing stimuli that are rich and yet both reproducible and amenable to experimental manipulations is technically challenging, and even more so if a closed-loop scenario is required. In this work, we present a novel approach to solve this problem, connecting robotics and neural network simulators. We implement a middleware solution that bridges the Robotic Operating System (ROS) to the Multi-Simulator Coordinator (MUSIC). This enables any robotic and neural simulators that implement the corresponding interfaces to be efficiently coupled, allowing real-time performance for a wide range of configurations. This work extends the toolset available for researchers in both neurorobotics and computational neuroscience, and creates the opportunity to perform closed-loop experiments of arbitrary complexity to address questions in multiple areas, including embodiment, agency, and reinforcement learning. PMID:27536234

  20. Closed Loop Interactions between Spiking Neural Network and Robotic Simulators Based on MUSIC and ROS.

    Science.gov (United States)

    Weidel, Philipp; Djurfeldt, Mikael; Duarte, Renato C; Morrison, Abigail

    2016-01-01

    In order to properly assess the function and computational properties of simulated neural systems, it is necessary to account for the nature of the stimuli that drive the system. However, providing stimuli that are rich and yet both reproducible and amenable to experimental manipulations is technically challenging, and even more so if a closed-loop scenario is required. In this work, we present a novel approach to solve this problem, connecting robotics and neural network simulators. We implement a middleware solution that bridges the Robotic Operating System (ROS) to the Multi-Simulator Coordinator (MUSIC). This enables any robotic and neural simulators that implement the corresponding interfaces to be efficiently coupled, allowing real-time performance for a wide range of configurations. This work extends the toolset available for researchers in both neurorobotics and computational neuroscience, and creates the opportunity to perform closed-loop experiments of arbitrary complexity to address questions in multiple areas, including embodiment, agency, and reinforcement learning. PMID:27536234

  1. What Controls DNA Looping?

    OpenAIRE

    Perez, Pamela J.; Nicolas Clauvelin; Grosner, Michael A.; Colasanti, Andrew V.; Olson, Wilma K.

    2014-01-01

    The looping of DNA provides a means of communication between sequentially distant genomic sites that operate in tandem to express, copy, and repair the information encoded in the DNA base sequence. The short loops implicated in the expression of bacterial genes suggest that molecular factors other than the naturally stiff double helix are involved in bringing the interacting sites into close spatial proximity. New computational techniques that take direct account of the three-dimensional stru...

  2. Determinants of RNA hairpin loop-loop complex stability.

    Science.gov (United States)

    Gregorian, R S; Crothers, D M

    1995-05-19

    Complexes formed by RNA hairpin loops with complementary loop sequences derived from Escherichia coli RNA I and RNA II, which are involved in the control of DNA replication of plasmid ColE1, have been analyzed to determine the sequence and structural elements required to achieve full affinity. Of particular interest is the origin of the enhanced stability of the complex formed by hairpin loops whose loop sequences have been inverted 5' to 3' with respect to wild-type sequences. Full complementarity of the two interacting loops is required to achieve full or enhanced affinity, while the stems of the two hairpins can differ. The major determinant of enhanced affinity lies in the base-pairs formed at positions 1 and 7 of the loops, together with the two base-pairs of each stem which are closest to the loop. Sequence variation in the middle of the loops, or further down the stem away from the loops, exerts only a modest influence on complex stability. We incorporate these results into a model for the loop-loop interaction which accounts for the importance of positions one and seven and the first two nucleotides of the stem, while providing potentially unique structures for recognition by the RNA one modulator protein. PMID:7539081

  3. Primitive Non-Powerful Symmetric Loop-Free Signed Digraphs with Base 3 and Minimum Number of Arcs

    Institute of Scientific and Technical Information of China (English)

    Lihua YOU; Yuhan WU

    2013-01-01

    Let S be a primitive non-powerful symmetric loop-free signed digraph on even n vertices with base 3 and minimum number of arcs.In [Lihua YOU,Yuhan WU.Primitive nonpowerful symmetric loop-free signed digraphs with given base and minimum number of arcs.Linear Algebra Appl.,2011,434(5),1215-1227],authors conjectured that D is the underlying digraph of S with exp(D) =3 if and only if D is isomorphic to EDn,3,3,where EDn,3,3 =(V,A)is a digraph with V ={1,2,...,n},A ={(1,i),(i,1) | 3 ≤ i ≤ n} ∪ {(2i-1,2i),(2i,2i-1) |2 ≤ i ≤ n/2} ∪ {(2,3),(3,2),(2,4),(4,2)}).In this paper,we show the conjecture is true and completely characterize the underlying digraphs which have base 3 and the minimum number of arcs.

  4. Choking loops on surfaces.

    Science.gov (United States)

    Feng, Xin; Tong, Yiying

    2013-08-01

    We present a method for computing "choking" loops--a set of surface loops that describe the narrowing of the volumes inside/outside of the surface and extend the notion of surface homology and homotopy loops. The intuition behind their definition is that a choking loop represents the region where an offset of the original surface would get pinched. Our generalized loops naturally include the usual 2g handles/tunnels computed based on the topology of the genus-g surface, but also include loops that identify chokepoints or bottlenecks, i.e., boundaries of small membranes separating the inside or outside volume of the surface into disconnected regions. Our definition is based on persistent homology theory, which gives a measure to topological structures, thus providing resilience to noise and a well-defined way to determine topological feature size. More precisely, the persistence computed here is based on the lower star filtration of the interior or exterior 3D domain with the distance field to the surface being the associated 3D Morse function. PMID:23744260

  5. Thin-film chemical sensors based on electron tunneling

    Science.gov (United States)

    Khanna, S. K.; Lambe, J.; Leduc, H. G.; Thakoor, A. P.

    1985-01-01

    The physical mechanisms underlying a novel chemical sensor based on electron tunneling in metal-insulator-metal (MIM) tunnel junctions were studied. Chemical sensors based on electron tunneling were shown to be sensitive to a variety of substances that include iodine, mercury, bismuth, ethylenedibromide, and ethylenedichloride. A sensitivity of 13 parts per billion of iodine dissolved in hexane was demonstrated. The physical mechanisms involved in the chemical sensitivity of these devices were determined to be the chemical alteration of the surface electronic structure of the top metal electrode in the MIM structure. In addition, electroreflectance spectroscopy (ERS) was studied as a complementary surface-sensitive technique. ERS was shown to be sensitive to both iodine and mercury. Electrolyte electroreflectance and solid-state MIM electroreflectance revealed qualitatively the same chemical response. A modified thin-film structure was also studied in which a chemically active layer was introduced at the top Metal-Insulator interface of the MIM devices. Cobalt phthalocyanine was used for the chemically active layer in this study. Devices modified in this way were shown to be sensitive to iodine and nitrogen dioxide. The chemical sensitivity of the modified structure was due to conductance changes in the active layer.

  6. Sequence-Based Polymorphisms in the Mitochondrial D-Loop and Potential SNP Predictors for Chronic Dialysis

    OpenAIRE

    Jin-Bor Chen; Yi-Hsin Yang; Wen-Chin Lee; Chia-Wei Liou; Tsu-Kung Lin; Yueh-Hua Chung; Li-Yeh Chuang; Cheng-Hong Yang; Hsueh-Wei Chang

    2012-01-01

    BACKGROUND: The mitochondrial (mt) displacement loop (D-loop) is known to accumulate structural alterations and mutations. The aim of this study was to investigate the prevalence of single nucleotide polymorphisms (SNPs) within the D-loop among chronic dialysis patients and healthy controls. METHODOLOGY AND PRINCIPAL FINDINGS: We enrolled 193 chronic dialysis patients and 704 healthy controls. SNPs were identified by large scale D-loop sequencing and bioinformatic analysis. Chronic dialysis p...

  7. A New GPS-based Digital Protection System for Smart Grids in Loop Structure

    Directory of Open Access Journals (Sweden)

    X. Liu

    2014-12-01

    Full Text Available This paper presents a new digital protection system to solve the protection challenges in future smart grids, i.e., fast protection and fault isolation in a loop-structured system with limited magnitude of fault current. The new system combines two protection algorithms, i.e., a differential protection as the primary algorithm and an overcurrent protection as the backup one. The new system uses real-time Ethernet and digital data acquisition techniques to overcome the restriction on data transmission over large grids. The current measurements at different locations are time-synchronized by GPS clocks, and then transmitted to a central computer via the Ethernet. As opposed to digital relays which often contain PMU functionality nowadays, this approach uses time stamps on the instantaneous current values. We build a prototype of the new system on a test-bed. The results from simulations and experiments have demonstrated that the protection system achieves fast and accurate protection.

  8. Security Loop Agents for the Enterprise Applications based on Resource Description Framework

    Directory of Open Access Journals (Sweden)

    Ahmed Isam Khaleel

    2011-01-01

    Full Text Available Security loop-holes can cost a fortune to a large enterprise organization providing e-commerce services. Meanwhile, the enterprise applications have been applied widely to simplify and generate better performance in managing the business tasks. Most of these applications (Enterprise Applications unable to provide a high level of security due to the new daily threats specially when malicious agents entered into agent platforms and destroyed other active agents during the agent performance for client query. Meanwhile, the security issues in these applications left in the system unintentionally but are intruded intentionally. Hence, this study aims to come out with suitable solution for the existing question on how to secure and platform independent environment for the enterprise applications? By designing architecture to provides a secure and platform independent environment for agents' communication.

  9. Using synthetic bacterial enhancers to reveal a looping-based mechanism for quenching-like repression

    Science.gov (United States)

    Brunwasser-Meirom, Michal; Pollak, Yaroslav; Goldberg, Sarah; Levy, Lior; Atar, Orna; Amit, Roee

    2016-02-01

    We explore a model for `quenching-like' repression by studying synthetic bacterial enhancers, each characterized by a different binding site architecture. To do so, we take a three-pronged approach: first, we compute the probability that a protein-bound dsDNA molecule will loop. Second, we use hundreds of synthetic enhancers to test the model's predictions in bacteria. Finally, we verify the mechanism bioinformatically in native genomes. Here we show that excluded volume effects generated by DNA-bound proteins can generate substantial quenching. Moreover, the type and extent of the regulatory effect depend strongly on the relative arrangement of the binding sites. The implications of these results are that enhancers should be insensitive to 10-11 bp insertions or deletions (INDELs) and sensitive to 5-6 bp INDELs. We test this prediction on 61 σ54-regulated qrr genes from the Vibrio genus and confirm the tolerance of these enhancers' sequences to the DNA's helical repeat.

  10. Chemical Sensors Based on Piezoresistive Cantilever Array

    Institute of Scientific and Technical Information of China (English)

    于晓梅; 张大成; 王丛舜; 杜先锋; 王小宝; 阮勇

    2003-01-01

    U-shaped and rectangle piezoresistive cantilever arrays have been designed with the analysing results of stress,noise and sensitivity of the cantilevers. Based on silicon micromachining technology, the piezoresistive cantilevers were fabricated by using polysilicon as the piezoresistive materials. With the measurement results of noise and sensitivity, the Hooge factor is calculated to be 3 × 10-3, the gauge factor is 27, and the minimum detectable deflection of piezoresistive cantilevers are calculated to be 1.0nm for rectangle cantilever and 0.5 nm for the Ushaped cantilever at a 6 V bias voltage and a 1000 Hz measurement bandwidth. Using polymer-coated cantilevers as individual sensors, their responses to water vapour and ammonia were tested by measuring their output voltage signals. The measured results show that the sensor sensitivity to ammonia can reach a few ppm and the sensor responses are quick.

  11. Piezoresistive Chemical Sensors Based on Functionalized Hydrogels

    Directory of Open Access Journals (Sweden)

    Margarita Guenther

    2014-06-01

    Full Text Available Thin films of analyte-specific hydrogels were combined with microfabricated piezoresistive pressure transducers to obtain chemomechanical sensors that can serve as selective biochemical sensors for a continuous monitoring of metabolites. The gel swelling pressure has been monitored in simulated physiological solutions by means of the output signal of piezoresistive sensors. The interference by fructose, human serum albumin, pH, and ionic concentration on glucose sensing was studied. With the help of a database containing the calibration curves of the hydrogel-based sensors at different values of pH and ionic strength, the corrected values of pH and glucose concentration were determined using a novel calibration algorithm.

  12. 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 o......, hair spray, sunscreen lotion, insect repellent lotion). The results of the virtual experimentations will be illustrated through the (initial) base case designs that were obtained and their verification through real experiments and/or available product data analysis......., 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...

  13. Carbon Nanotube-Based Chemical Sensors.

    Science.gov (United States)

    Meyyappan, M

    2016-04-27

    The need to sense gases and vapors arises in numerous scenarios in industrial, environmental, security and medical applications. Traditionally, this activity has utilized bulky instruments to obtain both qualitative and quantitative information on the constituents of the gas mixture. It is ideal to use sensors for this purpose since they are smaller in size and less expensive; however, their performance in the field must match that of established analytical instruments in order to gain acceptance. In this regard, nanomaterials as sensing media offer advantages in sensitivity, preparation of chip-based sensors and construction of electronic nose for selective detection of analytes of interest. This article provides a review of the use of carbon nanotubes in gas and vapor sensing. PMID:26959284

  14. Limited gene flow and partial isolation phylogeography of Himalayan snowcock Tetraogallus himalayensis based on part mitochondrial D-loop sequences

    Institute of Scientific and Technical Information of China (English)

    Xiaoli WANG; Jiangyong QU; Naifa LIU; Xinkang BAO; Sen SONG

    2011-01-01

    Himalayan snowcock Tetraogallus himalayensis are distributed in alpine and subalpine areas in China.We used mitochondrial DNA control-region data to investigate the origin and past demographic change in sixty-seven Himalayan snowcock T.himalayensis.The fragments of 1155 nucleotides from the control region of mitochondrial DNA were sequenced,and 57 polymorphic positions defined 37 haplotypes.A high level of genetic diversity was detected in all populations sampled and may be associated isolation of the mountains and habitat fragmentation and deterioration from Quaternary glaciations.In the phylogenetic tree,all haplotypes grouped into four groups:clade A (Kunlun Mountains clade),clade B (Northern Qinghai-Tibetan Plateau clade),clade C (Tianshan Mountains clade) and clade D (Kalakunlun Mountains clade).We found a low level of gene flow and significant genetic differentiation among all populations.Based on divergence time we suggest that the divergence of Himalayan snowcock occurred in the middle Pleistocene inter-glaciation,and expansion occurred in the glaciation.Analysis of mtDNA D-loop sequences confirmed demographic population expansion,as did our non-significant mismatch distribution analysis.In conclusion,limited gene flow and a pattern of partial isolation phylogeographic was found in geographic populations of T.himalayansis based on the analysis on mtDNA D-loop sequences [Current Zoology 57 (6):758-767,2011 ].

  15. A fuzzy-random programming for integrated closed-loop logistics network design by using priority-based genetic algorithm

    Directory of Open Access Journals (Sweden)

    Keyvan Kamandanipour

    2013-01-01

    Full Text Available Recovery of used products has steadily become interesting issue for research due to economic reasons and growing environmental or legislative concern. This paper presents a closed-loop logistics network design based on reverse logistics models. A mixed integer linear programming model is implemented to integrate logistics network design in order to prevent the sub-optimality caused by the separate design of the forward and reverse networks. The study presents a single product and multi-stage logistics network problem for the new and return products not only to determine subsets of logistics centers to be opened, but also to determine transportation strategy, which satisfies demand imposed by facilities and minimizes fixed opening and total shipping costs. Since the deterministic estimation of some parameters such as demand and rate of return of used products in closed loop logistics models is impractical, an uncertain programming is proposed. In this case, we assume there are several economic conditions with predefined probabilities calculated from historical data. Then by means of expert's opinion, a fuzzy variable is offered as customer's demand under each economic condition. In addition, demand and rate of return of products for each customer zone is presented by fuzzy-random variables, similarly. Therefore, a fuzzy-random programming is used and a priority-based genetic algorithm is proposed to solve large-scale problems.

  16. Nondestructive inspection of chemical warfare based on API-TOF

    International Nuclear Information System (INIS)

    Background: Real-time, fast, accurate, nondestructive inspection (NDI) and quantitative analysis for chemical warfare are very imperative for chemical defense, anti-terror and nation security. Purpose: Associated Particles Technique (APT)/Neutron Time of Flight (TOF) has been developed for non-invasive inspection of sealed containers with chemical warfare agents. Methods: A prototype equipment for chemical warfare is consisted of an APT neutron generator with a 3×3 matrix of semiconductor detectors of associated alpha-particles, the shielding protection of neutron and gamma-ray, arrayed NaI(Tl)-based detectors of gamma-rays, fully-digital data acquisition electronics, data analysis, decision-making software, support platform and remote control system. Inelastic scattering gamma-ray pulse height spectra of sarin, VX, mustard gas and adamsite induced by 14-MeV neutron are measured. The energies of these gamma rays are used to identify the inelastic scattering elements, and the intensities of the peaks at these energies are used to reveal their concentrations. Results: The characteristic peaks of inelastic scattering gamma-ray pulse height spectra show that the prototype equipment can fast and accurately inspect chemical warfare. Conclusion: The equipment can be used to detect not only chemical warfare agents but also other hazardous materials, such as chemical/toxic/drug materials, if their chemical composition is in any way different from that of the surrounding materials. (authors)

  17. Intelligent Forecasting of Sintered Ore's Chemical Components Based on SVM

    Institute of Scientific and Technical Information of China (English)

    ZHONG Luo; WANG Qingbo; YUAN Jingling

    2011-01-01

    Using object mathematical model of traditional control theory can not solve the forecasting problem of the chemical components of sintered ore. In order to control complicated chemical components in the manufacturing process of sintered ore, some key techniques for intelligent forecasting of the chemical components of sintered ore are studied in this paper. A new intelligent forecasting system based on SVM is proposed and realized. The results show that the accuracy of predictive value of every component is more than 90%. The application of our system in related companies is for more than one year and has shown satisfactory results.

  18. CANCER – THE ULTIMATUM FROM OUR CHEMICAL BASED CIVILIZATION

    Directory of Open Access Journals (Sweden)

    Shibabrata Pattanayak

    2014-06-01

    Full Text Available Cumulative effect of regular consumption of low amount of a large number of synthetic chemicals may create ultimately an environment inside our body leading to gereration of several types of diseases. Moreover, either DNA molecule of some tissue may get irreversible genetic damage or mutations or some tissue may start to grow abnormally due to the effect of those chemicals, both of which can lead to cancer, slowly but inevitably. To live with lesser number of hazardous diseases and for a healthy future generation, we must have to be conscious about these dangerous aspects of our chemical based civilization

  19. Experimental Investigations on a Novel Chemical Looping Combustion Configuration Étude expérimentale d’une nouvelle configuration de combustion en boucle chimique

    Directory of Open Access Journals (Sweden)

    Yazdanpanah M.M.

    2011-04-01

    Full Text Available Chemical Looping Combustion (CLC is a promising novel combustion technology involving inherent separation of carbon dioxide with minimum energy penalty. An oxygen carrier is employed to continuously transfer oxygen from the air reactor to the fuel reactor where the oxygen is delivered to the fuel. Consequently, direct contact between the air and fuel is prevented. The resulting flue gas is CO2-rich, without N2 dilution. The reduced oxygen carrier is then transported back to the air reactor for re-oxidation purposes, hence forming a chemical loop. Various CLC configurations have already been developed and tested on laboratory scales. However, more investigations are required to achieve feasible CLC processes. Among the different points to address, control of the solid circulation rate between the two reactors is of the highest importance regarding its effect on achievement of an appropriate oxygen transfer rate and solid oxidation degrees. Moreover, minimization of gas leakage between the fuel and air reactors is another important issue to be considered. A novel CLC configuration is proposed where reactions are carried out in two interconnected bubbling fluidized beds. Solid circulation rate control is achieved independently of gas flow rate in the reactors through use of pneumatic non-mechanical valves (L-valves. Moreover, loopseals are employed to minimize gas leakage while transferring solids. Experimental results from operation of a 10 kWth equivalent cold prototype are presented in this paper. The effect of operating variables on the solid circulation rate, gas leakage between the two beds and the pressure balance on all of the process elements is studied. The results demonstrate stable solid circulation with efficient control of the solid flow rate and effective gas tightness of the system. La combustion en boucle chimique (CLC est une nouvelle technologie prometteuse qui implique la separation inherente du dioxyde de carbone avec une perte

  20. Plasmonics Based Harsh Environment Compatible Chemical Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Michael Carpenter

    2012-01-15

    Au-YSZ, Au-TiO{sub 2} and Au-CeO{sub 2} nanocomposite films have been investigated as a potential sensing element for high-temperature plasmonic sensing of H{sub 2}, CO, and NO{sub 2} in an oxygen containing environment. The Au-YSZ and Au-TiO{sub 2} films were deposited using PVD methods, while the CeO{sub 2} thin film was deposited by molecular beam epitaxy (MBE) and Au was implanted into the as-grown film at an elevated temperature followed by high temperature annealing to form well-defined Au nanoclusters. Each of the films were characterized by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). For the gas sensing experiments, separate exposures to varying concentrations of H{sub 2}, CO, and NO{sub 2} were performed at a temperature of 500°C in oxygen backgrounds of 5.0, 10, and ~21% O{sub 2}. Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidation-reduction processes that fill or create oxygen vacancies in the respective metal oxides. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles or by changes in the dielectric constant surrounding the particles. Hyperspectral multivariate analysis was used to gauge the inherent selectivity of the film between the separate analytes. From principal component analysis (PCA), unique and identifiable responses were seen for each of the analytes. Linear discriminant analysis (LDA) was also used on the Au-CeO{sub 2} results and showed separation between analytes as well as trends in gas concentration. Results indicate that each of the films are is selective towards O{sub 2}, H{sub 2}, CO, and NO{sub 2} in separate exposures. However, when the films were analyzed in a sensor array based experiment, ie simultaneous exposures to the target gases, PCA analysis of the combined response showed an even greater selective character towards the target gases. Combined

  1. Graphene Electronic Device Based Biosensors and Chemical Sensors

    OpenAIRE

    Jiang, Shan

    2014-01-01

    Two-dimensional layered materials, such as graphene and MoS2, are emerging as an exciting material system for a new generation of atomically thin electronic devices. With their ultrahigh surface to volume ratio and excellent electrical properties, 2D-layered materials hold the promise for the construction of a generation of chemical and biological sensors with unprecedented sensitivity. In my PhD thesis, I mainly focus on graphene based electronic biosensors and chemical sensors. In the first...

  2. 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.

  3. Learning of Chemical Equilibrium through Modelling-Based Teaching

    Science.gov (United States)

    Maia, Poliana Flavia; Justi, Rosaria

    2009-01-01

    This paper presents and discusses students' learning process of chemical equilibrium from a modelling-based approach developed from the use of the "Model of Modelling" diagram. The investigation was conducted in a regular classroom (students 14-15 years old) and aimed at discussing how modelling-based teaching can contribute to students learning…

  4. Comparison between solar utilization of a closed microalgae-based bio-loop and that of a stand-alone photovoltaic system.

    Science.gov (United States)

    Jin, Qiang; Chen, Lei; Li, Aimin; Liu, Fuqiang; Long, Chao; Shan, Aidang; Borthwick, Alistair G L

    2015-05-01

    This study compared the solar energy utilization of a closed microalgae-based bio-loop for energy efficient production of biogas with fertilizer recovery against that of a stand-alone photovoltaic (PV) system. The comparison was made from the perspective of broad life cycle assessment, simultaneously taking exergy to be the functional unit. The results indicated that the bio-loop was more environmentally competitive than an equivalent stand-alone PV system, but had higher economic cost due to high energy consumption during the operational phase. To fix the problem, a patented, interior pressurization scheduling method was used to operate the bio-loop, with microalgae and aerobic bacterial placed together in the same reactor. As a result, the overall environmental impact and total investment were respectively reduced by more than 75% and 84%, a vast improvement on the bio-loop.

  5. Fold classification based on secondary structure – how much is gained by including loop topology?

    Directory of Open Access Journals (Sweden)

    Przytycka Teresa

    2006-03-01

    Full Text Available Abstract Background It has been proposed that secondary structure information can be used to classify (to some extend protein folds. Since this method utilizes very limited information about the protein structure, it is not surprising that it has a higher error rate than the approaches that use full 3D fold description. On the other hand, the comparing of 3D protein structures is computing intensive. This raises the question to what extend the error rate can be decreased with each new source of information, especially if the new information can still be used with simple alignment algorithms. We consider the question whether the information about closed loops can improve the accuracy of this approach. While the answer appears to be obvious, we had to overcome two challenges. First, how to code and to compare topological information in such a way that local alignment of strings will properly identify similar structures. Second, how to properly measure the effect of new information in a large data sample. We investigate alternative ways of computing and presenting this information. Results We used the set of beta proteins with at most 30% pairwise identity to test the approach; local alignment scores were used to build a tree of clusters which was evaluated using a new log-odd cluster scoring function. In particular, we derive a closed formula for the probability of obtaining a given score by chance.Parameters of local alignment function were optimized using a genetic algorithm. Of 81 folds that had more than one representative in our data set, log-odds scores registered significantly better clustering in 27 cases and significantly worse in 6 cases, and small differences in the remaining cases. Various notions of the significant change or average change were considered and tried, and the results were all pointing in the same direction. Conclusion We found that, on average, properly presented information about the loop topology improves noticeably

  6. An Adaptive Quadrature Signal Generation Based Single-Phase Phase-Locked Loop for Grid-Connected Applications

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Abusorrah, Abdullah;

    2016-01-01

    The quadrature signal generation based phase-locked loops (QSG-PLLs) are highly popular for synchronization purposes in single-phase systems. The main difference among these PLLs often lies in the technique they use for creating the fictitious quadrature component. One of the easiest QSG approaches...... is delaying the original single-phase signal by a quarter of a cycle. The PLL with such QSG technique is often called the transfer delay based PLL (TD-PLL). The TD-PLL benefits from a simple structure, rather fast dynamic response, and a good detection accuracy when the grid frequency is at its nominal value......, but it suffers from a phase offset error and double frequency oscillatory error in the estimated phase and frequency in the presence of frequency drifts. In this paper, a simple yet effective approach to remove the aforementioned errors of the TD-PLL is proposed. The resultant PLL structure is called...

  7. Collective estimation of multiple bivariate density functions with application to angular-sampling-based protein loop modeling

    KAUST Repository

    Maadooliat, Mehdi

    2015-10-21

    This paper develops a method for simultaneous estimation of density functions for a collection of populations of protein backbone angle pairs using a data-driven, shared basis that is constructed by bivariate spline functions defined on a triangulation of the bivariate domain. The circular nature of angular data is taken into account by imposing appropriate smoothness constraints across boundaries of the triangles. Maximum penalized likelihood is used to fit the model and an alternating blockwise Newton-type algorithm is developed for computation. A simulation study shows that the collective estimation approach is statistically more efficient than estimating the densities individually. The proposed method was used to estimate neighbor-dependent distributions of protein backbone dihedral angles (i.e., Ramachandran distributions). The estimated distributions were applied to protein loop modeling, one of the most challenging open problems in protein structure prediction, by feeding them into an angular-sampling-based loop structure prediction framework. Our estimated distributions compared favorably to the Ramachandran distributions estimated by fitting a hierarchical Dirichlet process model; and in particular, our distributions showed significant improvements on the hard cases where existing methods do not work well.

  8. Model-Based Closed-Loop Glucose Control in Type 1 Diabetes: The DiaCon Experience

    DEFF Research Database (Denmark)

    Schmidt, Signe; Boiroux, Dimitri; Duun-Henriksen, Anne Katrine;

    2013-01-01

    Background: To improve type 1 diabetes mellitus (T1DM) management, we developed a model predictive control (MPC) algorithm for closed-loop (CL) glucose control based on a linear second-order deterministic-stochastic model. The deterministic part of the model is specified by three patient...... crossover studies. Study 1 compared CL with open-loop (OL) control. Study 2 compared glucose control after CL initiation in the euglycemic (CL-Eu) and hyperglycemic (CL-Hyper) ranges, respectively. Patients were studied from 22:00–07:00 on two separate nights. Results: Each study included six T1DM patients...... mg/dl (117–133 mg/dl) and 69.0% (30.7–77.9%) in CL-Eu and 149 mg/dl (140–193 mg/dl) and 48.2% (34.9–72.5%) in CL-Hyper, respectively. Conclusions: This study suggests that our novel MPC algorithm can safely and effectively control glucose overnight, also when CL control is initiated during...

  9. Variable Sampling Composite Observer Based Frequency Locked Loop and its Application in Grid Connected System

    Directory of Open Access Journals (Sweden)

    ARUN, K.

    2016-05-01

    Full Text Available A modified digital signal processing procedure is described for the on-line estimation of DC, fundamental and harmonics of periodic signal. A frequency locked loop (FLL incorporated within the parallel structure of observers is proposed to accommodate a wide range of frequency drift. The error in frequency generated under drifting frequencies has been used for changing the sampling frequency of the composite observer, so that the number of samples per cycle of the periodic waveform remains constant. A standard coupled oscillator with automatic gain control is used as numerically controlled oscillator (NCO to generate the enabling pulses for the digital observer. The NCO gives an integer multiple of the fundamental frequency making it suitable for power quality applications. Another observer with DC and second harmonic blocks in the feedback path act as filter and reduces the double frequency content. A systematic study of the FLL is done and a method has been proposed to design the controller. The performance of FLL is validated through simulation and experimental studies. To illustrate applications of the new FLL, estimation of individual harmonics from nonlinear load and the design of a variable sampling resonant controller, for a single phase grid-connected inverter have been presented.

  10. Power Hardware-in-the-Loop-Based Anti-Islanding Evaluation and Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Schoder, Karl [Florida State Univ., Tallahassee, FL (United States). Ceter for Advanced Power Systems (CAPS); Langston, James [Florida State Univ., Tallahassee, FL (United States). Ceter for Advanced Power Systems (CAPS); Hauer, John [Florida State Univ., Tallahassee, FL (United States). Ceter for Advanced Power Systems (CAPS); Bogdan, Ferenc [Florida State Univ., Tallahassee, FL (United States). Ceter for Advanced Power Systems (CAPS); Steurer, Michael [Florida State Univ., Tallahassee, FL (United States). Ceter for Advanced Power Systems (CAPS); Mather, Barry [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-10-01

    The National Renewable Energy Laboratory (NREL) teamed with Southern California Edison (SCE), Clean Power Research (CPR), Quanta Technology (QT), and Electrical Distribution Design (EDD) to conduct a U.S. Department of Energy (DOE) and California Public Utility Commission (CPUC) California Solar Initiative (CSI)-funded research project investigating the impacts of integrating high-penetration levels of photovoltaics (PV) onto the California distribution grid. One topic researched in the context of high-penetration PV integration onto the distribution system is the ability of PV inverters to (1) detect islanding conditions (i.e., when the distribution system to which the PV inverter is connected becomes disconnected from the utility power connection) and (2) disconnect from the islanded system within the time specified in the performance specifications outlined in IEEE Standard 1547. This condition may cause damage to other connected equipment due to insufficient power quality (e.g., over-and under-voltages) and may also be a safety hazard to personnel that may be working on feeder sections to restore service. NREL teamed with the Florida State University (FSU) Center for Advanced Power Systems (CAPS) to investigate a new way of testing PV inverters for IEEE Standard 1547 unintentional islanding performance specifications using power hardware-in-loop (PHIL) laboratory testing techniques.

  11. Electrochemical techniques for characterization of stem-loop probe and linear probe-based DNA sensors.

    Science.gov (United States)

    Lai, Rebecca Y; Walker, Bryce; Stormberg, Kent; Zaitouna, Anita J; Yang, Weiwei

    2013-12-15

    Here we present a summary of the sensor performance of the stem-loop probe (SLP) and linear probe (LP) electrochemical DNA sensors when interrogated using alternating current voltammetry (ACV), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). Specifically, we identified one critical parameter for each voltammetric technique that can be adjusted for optimal sensor performance. Overall, the SLP sensor displayed good sensor performance (i.e., 60+% signal attenuation in the presence of the target) over a wider range of experimental conditions when compared to the LP sensor. When used with ACV, the optimal frequency range was found to be between 5 and 5000 Hz, larger than the 5-100 Hz range observed with the LP sensor. A similar trend was observed for the two sensors in CV; the LP sensor was operational only at scan rates between 30 and 100 V/s, whereas the SLP sensor performed well at scan rates between 1 and 1000 V/s. Unlike ACV and CV, DPV has demonstrated to be a more versatile sensor interrogation technique for this class of sensors. Despite the minor differences in total signal attenuation upon hybridization to the target DNA, both SLP and LP sensors performed optimally under most pulse widths used in this study. More importantly, when used with longer pulse widths, both sensors showed "signal-on" behavior, which is generally more desirable for sensor applications.

  12. An open-loop RFOG based on harmonic division technique to suppress LD's intensity modulation noise

    Science.gov (United States)

    Ying, Diqing; Wang, Zeyu; Mao, Jianmin; Jin, Zhonghe

    2016-11-01

    A harmonic division technique is proposed for an open-loop resonator fiber optic gyro (RFOG) to suppress semiconductor laser diode's (LD's) intensity modulation noise. The theoretical study indicates the RFOG with this technique is immune to the intensity noise. The simulation and experimental results show this technique would lead to a diminished linear region, which still could be acceptable for an RFOG applied to low rotation rate detection. The tests for the gyro output signal are carried out with/without noise suppressing methods, including the harmonic division technique and previously proposed signal compensation technique. With the harmonic division technique at the rotation rate of 10 deg/s, the stability of gyro output signal is improved from 1.07 deg/s to 0.0361 deg/s, whose noise suppressing ratio is more than 3 times as that of the signal compensation technique. And especially, a 3.12 deg/s signal jump is significantly removed with the harmonic division technique; in contrast, a residual 0.36 deg/s signal jump still exists with the signal compensation technique. It is concluded the harmonic division technique does work in intensity noise suppressing under dynamic condition, and it is superior to the signal compensation technique.

  13. Spatiotemporal dynamics of a digital phase-locked loop based coupled map lattice system

    Science.gov (United States)

    Banerjee, Tanmoy; Paul, Bishwajit; Sarkar, B. C.

    2014-03-01

    We explore the spatiotemporal dynamics of a coupled map lattice (CML) system, which is realized with a one dimensional array of locally coupled digital phase-locked loops (DPLLs). DPLL is a nonlinear feedback-controlled system widely used as an important building block of electronic communication systems. We derive the phase-error equation of the spatially extended system of coupled DPLLs, which resembles a form of the equation of a CML system. We carry out stability analysis for the synchronized homogeneous solutions using the circulant matrix formalism. It is shown through extensive numerical simulations that with the variation of nonlinearity parameter and coupling strength the system shows transitions among several generic features of spatiotemporal dynamics, viz., synchronized fixed point solution, frozen random pattern, pattern selection, spatiotemporal intermittency, and fully developed spatiotemporal chaos. We quantify the spatiotemporal dynamics using quantitative measures like average quadratic deviation and spatial correlation function. We emphasize that instead of using an idealized model of CML, which is usually employed to observe the spatiotemporal behaviors, we consider a real world physical system and establish the existence of spatiotemporal chaos and other patterns in this system. We also discuss the importance of the present study in engineering application like removal of clock-skew in parallel processors.

  14. Process Design and Evaluation for Chemicals Based on Renewable Resources

    DEFF Research Database (Denmark)

    Fu, Wenjing

    One of the key steps in process design is choosing between alternative technologies, especially for processes producing bulk and commodity chemicals. Recently, driven by the increasing oil prices and diminishing reserves, the production of bulk and commodity chemicals from renewable feedstocks has...... development of chemicals based on renewable feedstocks. As an example, this thesis especially focuses on applying the methodology in process design and evaluation of the synthesis of 5-hydroxymethylfurfural (HMF) from the renewable feedstock glucose/fructose. The selected example is part of the chemoenzymatic...... gained considerable interest. Renewable feedstocks usually cannot be converted into fuels and chemicals with existing process facilities due to the molecular functionality and variety of the most common renewable feedstock (biomass). Therefore new types of catalytic methods as well as new types...

  15. Mindfulness-based cognitive therapy to treat multiple chemical sensitivities

    DEFF Research Database (Denmark)

    Skovbjerg, S; Hauge, Christian Riis; Rasmussen, Alice;

    2012-01-01

    of an 8-week mindfulness-based cognitive therapy program (MBCT) for adults with MCS and to evaluate possible effects on psychological distress and illness perception. The study design was a randomized clinical trial. The MBCT programme comprised 8 weekly sessions of 2½ hours. Forty-two adults were......Multiple chemical sensitivities (MCS) is a medically unexplained and socially disabling disorder characterized by negative health effects attributed to exposure to common airborne chemicals. Currently, there is no evidence-based treatment. The objectives of the study were to assess the feasibility...

  16. Chemical Functionalization Effects on Cubane-Based Chain Electronic Transport

    Directory of Open Access Journals (Sweden)

    Konstantin P. Katin

    2015-01-01

    Full Text Available We report electronic structure calculations in chemically functionalized linear cubane-based chains. The effects of covalent chemical attachments on chain transport properties are examined with nonorthogonal tight-binding model (NTBM considering Landauer-Büttiker formalism. The covalent bonding of even a single-type functional group is shown to considerably alter the conductance of the chain. For similar radical doping density, electronic characteristics are found to range from insulator to narrow-gap semiconductor depending on the nature of the covalent bonding. Therefore it has become possible to tune electronic properties of the cubane-based one-dimensional oligomers by the functionalization for nanoelectronic applications.

  17. Structural and Chemical Diversity of Tl-Based Cuprate Superconductors

    Institute of Scientific and Technical Information of China (English)

    信赢

    2003-01-01

    The Tl-based cuprate superconductor family is the largest family in crystal structure and chemical composition among all high Tc cuprate superconductors. The Tl family can be divided into two sub-families, the Tl single layer family and the Tl double layer family, based on their crystal structural characteristics. The Tl single layer family is an ideal material for investigating the evolution of crystalline formation, charge carrier density, chemical composition, transport properties, superconductivity and their relationships. The Tl family contains almostall possible crystal structures discovered in high-Tc cuprate superconductors. Tl cuprate superconductors are of great importance not only in studying high-temperature superconductivity but also in commercial applications.

  18. Adaptive optics in nonlinear microscopy implemented with open-loop control and EMCCD-based Shack-Hartmann wavefront sensor

    Science.gov (United States)

    Sun, Wei

    Nonlinear microscopy, with its unique advantages over conventional confocal fluorescence microscopy, has been widely adopted to study biological processes at the cellular level. However, like all other high-resolution optical imaging techniques, nonlinear microscopy suffers from focal degradation due to optical aberrations in the sample as a result of refractive index mismatch. Optical aberrations distort the wavefront of the excitation beam, causing the focal spot to be larger than the diffraction limit. Since the fluorescence efficiency scales nonlinearly with the profile of the focusing excitation beam, aberrations further degrade the image brightness in addition to resolution. In this dissertation I describe the design, characterization and experimentation of an adaptive optics (AO) nonlinear laser scanning microscope implemented with open-loop control and an EMCCD-based Shack-Hartmann wavefront sensor (EMCCD SHWFS) for aberration compensation. Adaptive optics (AO), originally designed for ground-based astronomical observatories to correct for the aberrations from atmospheric turbulence while imaging distant stars and planets, has benefited many biomedical imaging platforms. We integrated a microelectromechanical system (MEMS) deformable mirror (DM) into our nonlinear laser scanning microscope. With an accurate open-loop control mechanism, which predicts the control voltages and generates a prescribed surface shape on the MEMS DM, known aberrations in the system can be compensated for with this computationally simple and inherently fast method. The use of a nonlinear guide star imbedded within the sample can reflect the sample aberration. However, the low level of nonlinear fluorescence signal is usually detected by photomultiplier tubes (PMT) and is below the sensitivity of a conventional charge-coupled device (CCD) based Shack-Hartmann wavefront sensor. This dissertation also describes the design of an EMCCD SHWFS to measure the wavefront distortion from the

  19. THE DESIGN OF AN ALL-DIGITAL PHASE-LOCKED LOOP WITH LOW JITTER BASED ON ISF ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    Deng Xiaoying; Yang Jun; Shi Longxing; Chen Xin

    2008-01-01

    A low jitter All-Digital Phase-Locked Loop (ADPLL) used as a clock generator is designed.The Digital-Controlled Oscillator (DCO) for this ADPLL is a seven-stage ring oscillator with the delay of each stage changeable. Based on the Impulse Sensitivity Function (ISF) analysis,an effective way is proposed to reduce the ADPLL's jitter by the careful design of the sizes of the inverters used in the DCO with a simple architecture other than a complex one. The ADPLL is implemented in a 0.18μm CMOS process with 1.8V supply voltage,occupies 0.046mm2 of on-chip area. According to the measured results,the ADPLL can operate from 108MHz to 304MHz,and the peak-to-peak jitter is 139ps when the DCO's output frequency is 188MHz.

  20. Study of Flow-Assisted Corrosion of AZ91D Magnesium Alloy in Loop System Based on Array Electrode Technology

    Directory of Open Access Journals (Sweden)

    Hualiang Huang

    2015-01-01

    Full Text Available A loop system was used to investigate flow-assisted corrosion (FAC of AZ91D magnesium alloy at an elbow based on array electrode technology by potentiodynamic polarization, computational fluid dynamics, simulation and surface analysis. The experimental results demonstrate the fluid hydrodynamics plays a significant role in the FAC of AZ91D magnesium alloy. The corrosion rate increases from the outer wall to the inner wall of the elbow, with the higher corrosion rate corresponding to the higher flow velocity and larger shear stress at the elbow. The maximum corrosion rate appears at the innermost wall of the elbow, the location with the maximum flow velocity and shear stress.

  1. From Concept-to-Flight: An Active Active Fluid Loop Based Thermal Control System for Mars Science Laboratory Rover

    Science.gov (United States)

    Birur, Gajanana C.; Bhandari, Pradeep; Bame, David; Karlmann, Paul; Mastropietro, A. J.; Liu, Yuanming; Miller, Jennifer; Pauken, Michael; Lyra, Jacqueline

    2012-01-01

    The Mars Science Laboratory (MSL) rover, Curiosity, which was launched on November 26, 2011, incorporates a novel active thermal control system to keep the sensitive electronics and science instruments at safe operating and survival temperatures. While the diurnal temperature variations on the Mars surface range from -120 C to +30 C, the sensitive equipment are kept within -40 C to +50 C. The active thermal control system is based on a single-phase mechanically pumped fluid loop (MPFL) system which removes or recovers excess waste heat and manages it to maintain the sensitive equipment inside the rover at safe temperatures. This paper will describe the entire process of developing this active thermal control system for the MSL rover from concept to flight implementation. The development of the rover thermal control system during its architecture, design, fabrication, integration, testing, and launch is described.

  2. Correlation between the Cyclic Stress Behavior and Microstructure in 316LN based on the Analysis of Hysteresis Loops

    Institute of Scientific and Technical Information of China (English)

    CHANG Bo; ZHANG Zheng

    2014-01-01

    Total strain controlled cyclic test was performed on 316LN under uniaxial loadings. Through the partitioning of hysteresis loops, the evolution of two components of cyclic flow stress, the internal and effective stresses, was reported. The former one determines the cyclic stress response. Based on the transmission electron microscopic (TEM) observation on specimens loaded with scheduled cycles, it is found that planar dislocation structures prevail during the entire cyclic process at low strain amplitude, while a remarkable dislocation rearrangement from planar structures to heterogeneous spatial distributions is companied by a cyclic softening behavior at high strain amplitude. The competition between the evolution of the intergranular and the intragranular components of the internal stress caused by the transition of slip mode induces the cyclic hardening and softening at high strain levels. The intergranular internal stress represents the most part of the internal stress at low strain level.

  3. A novel fiber-laser-based fiber Bragg grating strain sensor with high-birefringence Sagnac fiber loop mirror

    Institute of Scientific and Technical Information of China (English)

    Ou Xu; Shaohua Lu; Suchun Feng; Shuisheng Jian

    2008-01-01

    A novel fiber-laser-based strain sensor is proposed and experimentally demonstrated. The laser cavity is composed of a high-birefringence Sagnac fiber loop mirror (HiBi-SFLM) and a fiher Bragg grating (FBG) which also acts as a strain-sensing element. In the linear region of the HiBi-SFI,M reflection spectrum, when the strain applied on the FBG makes the Bragg grating wavelength shift,, the laser output power changes due to reflectivity variation of the HiBi-SFLM. Experimental results show that the laser output power varies ahnost linearly with the applied strain. The measurement of the output power can be performed by a conventional photo-detector.

  4. A widely tunable fiber ring laser with closed loop control based on high-precision stepper motor

    Science.gov (United States)

    Wang, Li-li; Xin, Xiang-jun; Zhu, Lin-wei

    2016-05-01

    A tunable single-longitudinal mode erbium-doped fiber ring laser based on stepper motor and closed loop control is proposed and demonstrated. The system consists of an erbium-doped fiber (EDF), a tunable fiber Bragg grating (FBG) filter and a wavelength detector. The characteristics of output laser, such as output power, power stability and 3-dB linewidth, are investigated in the operation range of 1 531—1 569 nm. The repeated experimental results of the fiber laser show that the 3-dB linewidth is less than 17 ps, the side-mode suppression ratio ( SMSR) is up to 60 dB, the output power is up to 1.37 dBm, and the power variation is less than 0.61 dB.

  5. Point-of-care multiplexed assays of nucleic acids using microcapillary-based loop-mediated isothermal amplification.

    Science.gov (United States)

    Zhang, Yi; Zhang, Lu; Sun, Jiashu; Liu, Yulei; Ma, Xingjie; Cui, Shangjin; Ma, Liying; Xi, Jianzhong Jeff; Jiang, Xingyu

    2014-07-15

    This report demonstrates a straightforward, robust, multiplexed and point-of-care microcapillary-based loop-mediated isothermal amplification (cLAMP) for assaying nucleic acids. This assay integrates capillaries (glass or plastic) to introduce and house sample/reagents, segments of water droplets to prevent contamination, pocket warmers to provide heat, and a hand-held flashlight for a visual readout of the fluorescent signal. The cLAMP system allows the simultaneous detection of two RNA targets of human immunodeficiency virus (HIV) from multiple plasma samples, and achieves a high sensitivity of two copies of standard plasmid. As few nucleic acid detection methods can be wholly independent of external power supply and equipment, our cLAMP holds great promise for point-of-care applications in resource-poor settings. PMID:24937125

  6. The Complementarity of the Loop to the Stem in DNA Pseudoknots Gives Rise to Local TAT Base-Triplets.

    Science.gov (United States)

    Reiling-Steffensmeier, Calliste; Marky, Luis A

    2016-01-01

    Pseudoknots belong to an RNA structural motif that has significant roles in the biological function of RNA. An example is ribosomal frameshifting; in this mechanism, the formation of a local triplex changes the reading frame that allows for differences in the translation of mRNAs. In this work, we have used a combination of temperature-dependent UV spectroscopy and differential scanning calorimetry (DSC) to determine the unfolding thermodynamics of a set of DNA pseudoknots with the following sequence: d(TCTCTTnAAAAAAAAGAGAT5TTTTTTT), where "Tn" is a thymine loop with n=5 (PsK-5), 7 (PsK-7), 9 (PsK-9), or 11 (PsK-11). All four oligonucleotides form intramolecular pseudoknots, and the increase in the length of this loop yielded more stable pseudoknots due to higher transition temperatures and higher unfolding enthalpies. This indicates formation of one and three TAT/TAT stacks in PsK-9 and PsK-11, respectively. We have flipped one AT for a TA base pair in the core stem of these pseudoknots, preventing in this way the formation of these base-triplet stacks. The DSC curves of these pseudoknots yielded lower unfolding enthalpies, confirming the formation of a local triplex in PsK-9 and PsK-11. Furthermore, we have investigated the reaction of PsK-5 and PsK-9 with their partially complementary strands: directly by isothermal titration calorimetry and indirectly by creating a Hess cycle with the DSC data. Relative to the PsK-5 reaction, PsK-9 reacts with its complementary strand with less favorable free energy and enthalpy contributions; this indicates PsK-9 is more stable and more compact due to the formation of a local triplex.

  7. The Complementarity of the Loop to the Stem in DNA Pseudoknots Gives Rise to Local TAT Base-Triplets.

    Science.gov (United States)

    Reiling-Steffensmeier, Calliste; Marky, Luis A

    2016-01-01

    Pseudoknots belong to an RNA structural motif that has significant roles in the biological function of RNA. An example is ribosomal frameshifting; in this mechanism, the formation of a local triplex changes the reading frame that allows for differences in the translation of mRNAs. In this work, we have used a combination of temperature-dependent UV spectroscopy and differential scanning calorimetry (DSC) to determine the unfolding thermodynamics of a set of DNA pseudoknots with the following sequence: d(TCTCTTnAAAAAAAAGAGAT5TTTTTTT), where "Tn" is a thymine loop with n=5 (PsK-5), 7 (PsK-7), 9 (PsK-9), or 11 (PsK-11). All four oligonucleotides form intramolecular pseudoknots, and the increase in the length of this loop yielded more stable pseudoknots due to higher transition temperatures and higher unfolding enthalpies. This indicates formation of one and three TAT/TAT stacks in PsK-9 and PsK-11, respectively. We have flipped one AT for a TA base pair in the core stem of these pseudoknots, preventing in this way the formation of these base-triplet stacks. The DSC curves of these pseudoknots yielded lower unfolding enthalpies, confirming the formation of a local triplex in PsK-9 and PsK-11. Furthermore, we have investigated the reaction of PsK-5 and PsK-9 with their partially complementary strands: directly by isothermal titration calorimetry and indirectly by creating a Hess cycle with the DSC data. Relative to the PsK-5 reaction, PsK-9 reacts with its complementary strand with less favorable free energy and enthalpy contributions; this indicates PsK-9 is more stable and more compact due to the formation of a local triplex. PMID:26794363

  8. The accuracy and clinical feasibility of a new Bayesian-based closed-loop control system for propofol administration using the bispectral index as a controlled variable

    NARCIS (Netherlands)

    De Smet, Tom; Struys, Michel M. R. F.; Neckebroek, Martine M.; Van den Hauwe, Kristof; Bonte, Sjoert; Mortier, Eric P.

    2008-01-01

    BACKGROUND: Closed-loop control of the hypnotic component of anesthesia has been proposed in an attempt to optimize drug delivery. Here, we introduce a newly developed Bayesian-based, patient-individualized, model-based, adaptive control method for bispectral index (BIS) guided propofol infusion int

  9. A computerized loop based approach for identification of isomorphism and type of mobility in planar kinematic chains

    Indian Academy of Sciences (India)

    Manoj K Lohumi; Aas Mohammad; Irshad A Khan

    2015-04-01

    Some new invariants like chain string, link identification string, loop participation of joint frequency string and loop size frequency string of simple jointed kinematic chains are presented. The first step of the proposed method is to identify all possible loops of a kinematic chain and then these new invariants are developed. A modified loop-joint approach is proposed in this work as compared to the previous work in literature where loop-link matrix is formulated to search all the loops present in a kinematic chain. A computer program has been developed for formulating loop-joint matrix of kinematic chain and its all invariants. This method takes into consideration all the loops present, associated joints and links and is able to test isomorphism among kinematic chains and their inversions and also to detect type of mobility of multi degree of freedom kinematic chains. The proposed method is successfully tested for all kinematic chains upto five independent loops having any number of degree of freedom and no counter example is found. The detailed results of 9-link, M = 2 (mobility) and 10 link, M = 3 kinematic chains are provided with five types of mobility and results are in accordance with the results published in literature. The method is also explained with the help of some complex examples and presented in this paper.

  10. Durable chemical sensors based on field-effect transistors

    NARCIS (Netherlands)

    Reinhoudt, D.N.

    1995-01-01

    The design of durable chemical sensors based on field-effect transistors (FETs) is described. After modification of an ion-sensitive FET (ISFET) with a polysiloxane membrane matrix, it is possible to attach all electroactive components covalently. Preliminary results of measurements with a sodium-se

  11. Chemical Information in Scirus and BASE (Bielefeld Academic Search Engine)

    Science.gov (United States)

    Bendig, Regina B.

    2009-01-01

    The author sought to determine to what extent the two search engines, Scirus and BASE (Bielefeld Academic Search Engines), would be useful to first-year university students as the first point of searching for chemical information. Five topics were searched and the first ten records of each search result were evaluated with regard to the type of…

  12. Characterization of Chemical and Mechanical Properties of Polymer Based Nanocomposites

    OpenAIRE

    Wafy, Tamer

    2013-01-01

    Characterization of Chemical and Mechanical Properties of Polymer Based NanocompositesThe University of ManchesterTamer Wafy Doctor of Philosophy17 January, 2013One of the most significant issues in nanocomposite performance is improving the dispersion of carbon nanotubes (CNTs) in thermosetting or thermoplastic polymers in order to gain good mechanical properties. Several studies have investigated the fabrication of nanocomposites based on carbon nanotubes and analysed properties, but there ...

  13. Analysis of the effects of time delay in clock recovery circuits based on Phase-locked loops

    DEFF Research Database (Denmark)

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

    2004-01-01

    Influence of time delay in a balanced optical phase-locked loops (OPLL) with a proportional integrator (Pl) filter is investigated using a delayed differential equation (DDE) is investigated. The limitations, which a time delay imposes on the Pl filter bandwidth, at increasing values of loop gain...

  14. [Medicinal values and their chemical bases of Paris].

    Science.gov (United States)

    Wang, Yue-hu; Niu, Hong-mei; Zhang, Zhao-yun; Hu, Xiang-yang; Li, Heng

    2015-03-01

    Medicinal values and their chemical bases of Paris (Trilliaceae) are reviewed. Paris plants include 40 species and varieties. Among them, 18 ones are medicinal plants with similarity in traditional uses. Fourteen species have been studied phytochemically, which led to isolation of 207 compounds including 121 steroidal saponins. These saponins are major active constituents from Paris plants, which can explain the traditional uses of the plants to treat cancer, malignant boil, bleeding, gastritis, and so on. The similarity in medicinal uses and chemical constituents of Paris plants implies the possibility of resource substitution among these species. It is worth to further investigate Paris plants in chemical constituents, pharmacological activity, biological property, and toxicology. PMID:26087542

  15. 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.

  16. Chemical interaction matrix between reagents in a Purex based process

    International Nuclear Information System (INIS)

    The United States Department of Energy (DOE) is the responsible entity for the disposal of the United States excess weapons grade plutonium. DOE selected a PUREX-based process to convert plutonium to low-enriched mixed oxide fuel for use in commercial nuclear power plants. To initiate this process in the United States, a Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF) is under construction and will be operated by Shaw AREVA MOX Services at the Savannah River Site. This facility will be licensed and regulated by the U.S. Nuclear Regulatory Commission (NRC). A PUREX process, similar to the one used at La Hague, France, will purify plutonium feedstock through solvent extraction. MFFF employs two major process operations to manufacture MOX fuel assemblies: (1) the Aqueous Polishing (AP) process to remove gallium and other impurities from plutonium feedstock and (2) the MOX fuel fabrication process (MP), which processes the oxides into pellets and manufactures the MOX fuel assemblies. The AP process consists of three major steps, dissolution, purification, and conversion, and is the center of the primary chemical processing. A study of process hazards controls has been initiated that will provide knowledge and protection against the chemical risks associated from mixing of reagents over the life time of the process. This paper presents a comprehensive chemical interaction matrix evaluation for the reagents used in the PUREX-based process. Chemical interaction matrix supplements the process conditions by providing a checklist of any potential inadvertent chemical reactions that may take place. It also identifies the chemical compatibility/incompatibility of the reagents if mixed by failure of operations or equipment within the process itself or mixed inadvertently by a technician in the laboratories. (authors)

  17. Microstructural and Chemical Rejuvenation of a Ni-Based Superalloy

    Science.gov (United States)

    Yao, Zhiqi; Degnan, Craig C.; Jepson, Mark A. E.; Thomson, Rachel C.

    2016-10-01

    The microstructural evolution of the Ni-based superalloy CMSX-4 including the change in gamma prime morphology, size, and distribution after high-temperature degradation and subsequent rejuvenation heat treatments has been examined using field emission gun scanning electron microscopy and transmission electron microscopy. In this paper, it is shown that there are significant differences in the size of the `channels' between gamma prime particles, the degree of rafting, and the size of tertiary gamma prime particles in each of the different microstructural conditions studied. Chemical analysis has been carried out to compare rejuvenated and pre-service samples after the same subsequent degradation procedure. The results indicate that although the microstructures of pre-service and rejuvenated samples are similar, chemical differences are more pronounced in the rejuvenated samples, suggesting that chemical segregation from partitioning of the elements was not completely eliminated through the applied rejuvenation heat treatment. A number of modified rejuvenation heat treatment trials were carried out to reduce the chemical segregation prior to creep testing. The creep test results suggest that chemical segregation has an immeasurable influence on the short-term mechanical properties under the test conditions used here, indicating that further work is required to fully understand the suitability of specific rejuvenation heat treatments and their role in the extension of component life in power plant applications.

  18. Loop groups and noncommutative geometry

    CERN Document Server

    Carpi, Sebastiano

    2015-01-01

    We describe the representation theory of loop groups in terms of K-theory and noncommutative geometry. This is done by constructing suitable spectral triples associated with the level l projective unitary positive-energy representations of any given loop group LG. The construction is based on certain supersymmetric conformal field theory models associated with LG.

  19. 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

  20. Interdependent chemical-electrochemical steps in retrometabolism-based drug and safer chemical design.

    Science.gov (United States)

    Tókés, B; Suciu, G; Nagy, G

    2002-02-01

    An extension of the retrometabolic based drug (chemical) design concept, specifically the soft drug approach, to the family of nitrone compounds is presented. Nitrones oppose oxidative challenges by virtue of their ability to very rapidly trap free radical species that are more stable and biochemically less harmful than the original molecular fragments. Moreover, the spin adducts may undergo further transformations including reaction with a second radical and decomposition (hydrolysis) to hydroxylamines and carbonyl compounds. Nitrones and their spin adducts may generate nitric oxide in vivo, which, like nitrones themselves, exerts a number of diverse activities in phylogenetically distant species as well as opposing effects in related biological systems. It was described as a major messenger in the cardiovascular, immune, and nervous systems, in which it plays regulatory, signaling, cytoprotective, and cytotoxic effects. Nitrones play an important role in the synthesis of drugs belonging to chemically and pharmacologically very different classes. A combined chemical-electrochemical synthesis of nitrones has been elaborated. These compounds may be obtained from aldehydes or ketones and N-substituted hydroxylamines. These reactions were performed directly, in situ in the electrochemical cell, where phenylhydroxylamine obtained by electroreduction of nitrobenzene derivatives reacts with the carbonyl compound introduced in the cell. The kinetic and thermodynamic parameters of the processes were determined by analyzing the adequate polarographic curves. Differences between purely chemical and mixed chemical-electrochemical methods are discussed. Analysis of the experimental data permits optimization of the investigated process from a preparative point of view. Effects of structural factors were systematically evaluated. The proposed method may be useful for combinatorial chemistry as well.

  1. Closed-loop Supply Chain Information System Based on Service-oriented Architecture%基于SOA的闭环供应链信息系统研究

    Institute of Scientific and Technical Information of China (English)

    计三有; 仇艳丽

    2011-01-01

    深入分析了闭环供应链中信息管理面临的挑战和实现要求,介绍了面向服务的体系架构(SOA)的结构模型与技术,进而把SOA思想引入闭环供应链信息系统实现中,提出了一种新的闭环供应链信息系统架构方案,建立了基于SOA的闭环供应链信息系统模型,并详细分析了模型中各组成部分在整个系统中的作用,研究结果表明,该系统能够较好地解决闭环供应链信息集成的复杂性等问题.%Challenge and realization requirements of closed - loop supply chain information management were discussed. Structural model and technology of service - oriented architecture ( SOA) were introduced. The SOA idea was introduced to realize the closed - loop supply chain information system. A new architecture design for closed - loop supply chain information system was proposed. And SOA - based model for closed - loop supply chain information system was put forward. The function of each part in the model was emphatically analyzed. Research results show that the system can solve the complex problem of the closed - loop supply chain information system integration.

  2. Rapid and Sensitive Detection of RNA Viruses Based on Reverse Transcription Loop-Mediated Isothermal Amplification, Magnetic Nanoparticles, and Chemiluminescence.

    Science.gov (United States)

    Wang, Jiuhai; Lu, Peng; Yan, Jieni; Zhang, Yufan; Huang, Lanye; Ali, Zeeshan; Li, Zhiyang; He, Nongyue

    2016-04-01

    RNA viruses, particularly, the highly pathogenic avian influenza (HPAI) virus, pose serious health concerns, and cause huge economic losses worldwide. Diagnostic tools for the early detection of these deadly RNA viruses are urgently needed to implement treatment and disease control strategies. Conventional reverse transcription polymerase chain reaction (RT-PCR)-based chemiluminescent (RT-PCR-CL) detection is frequently used for the diagnosis of viral infections. However, the requirements for expensive PCR machines and longer thermocycling times are significant drawbacks. In this study, we propose a method based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) combined with chemiluminescence (CL) to detect H7N9 virus. The proposed method does not require any expensive instruments, and processing time is remarkably shortened compared to that of RT-PCR-CL. Since several factors including RT-LAMP temperature, probe concentration, hybridization temperature, and hybridization duration might affect the CL signal, each of these parameters was investigated and optimized. One thousand copies/mL of H7N9 RNA were detectable using the optimized RT-LAMP-CL method. The detection time was significantly reduced by using RT-LAMP, in comparison with conventional RT-PCR-CL. This technique holds great promise for viral detection and diagnosis, especially with regard to avian influenza virus. PMID:27301197

  3. Molecularly Imprinted Polymer/Metal Organic Framework Based Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Zhenzhong Guo

    2016-10-01

    Full Text Available The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are presented: molecularly imprinted MOF films and molecularly imprinted core-shell nanoparticles using MOF as core. The associated transduction modes are also discussed. A brief conclusion and future expectations are described herein.

  4. Model-based rational feedback controller design for closed-loop deep brain stimulation of Parkinson's disease

    Science.gov (United States)

    Gorzelic, P.; Schiff, S. J.; Sinha, A.

    2013-04-01

    Objective. To explore the use of classical feedback control methods to achieve an improved deep brain stimulation (DBS) algorithm for application to Parkinson's disease (PD). Approach. A computational model of PD dynamics was employed to develop model-based rational feedback controller design. The restoration of thalamocortical relay capabilities to patients suffering from PD is formulated as a feedback control problem with the DBS waveform serving as the control input. Two high-level control strategies are tested: one that is driven by an online estimate of thalamic reliability, and another that acts to eliminate substantial decreases in the inhibition from the globus pallidus interna (GPi) to the thalamus. Control laws inspired by traditional proportional-integral-derivative (PID) methodology are prescribed for each strategy and simulated on this computational model of the basal ganglia network. Main Results. For control based upon thalamic reliability, a strategy of frequency proportional control with proportional bias delivered the optimal control achieved for a given energy expenditure. In comparison, control based upon synaptic inhibitory output from the GPi performed very well in comparison with those of reliability-based control, with considerable further reduction in energy expenditure relative to that of open-loop DBS. The best controller performance was amplitude proportional with derivative control and integral bias, which is full PID control. We demonstrated how optimizing the three components of PID control is feasible in this setting, although the complexity of these optimization functions argues for adaptive methods in implementation. Significance. Our findings point to the potential value of model-based rational design of feedback controllers for Parkinson's disease.

  5. 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.

  6. A Criterion Based on Closed-loop Pilot-aircraft Systems for Predicting Flying Qualities

    Institute of Scientific and Technical Information of China (English)

    Tan Wenqian; A.V.Efremov; Qu Xiangju

    2010-01-01

    During the process of aircraft design,the mathematical model of pilot control behavior characteristics is always used to predict aircraft flying qualities (FQ).This is one of the important methods to avoid pilot-aircraft adverse coupling.In order to study the FQ criterion based on closedloop pilotaircraft systems,first,an experimental database is built,which includes 40 aircraft dynamics configurations and the corresponding flight simulation results.Second,the mathematical pilot models with a set of different aircraft configurations are obtained by this experimental database.Then,two FQ criteria,NealSmith criterion and Moscow Aviation Institute (MAI) criterion,are analyzed.And the relationship between the FQ level evaluated by actual pilot and the parameters of closedloop pilotaircraft systems is studied.Finally,an improved criterion of aircraft FQ is built based on the above two criteria.This new criterion is further used to predict FQ for four new aircraft dynamics configurations,and the prediction results verify its accuracy and practicability.

  7. An Adaptive Controller Based upon Continuous Estimation of the Closed Loop Frequency Response

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen

    1987-10-01

    Full Text Available An adaptive control algorithm based upon on-line estimation of the -180 degree shift frequency and the gain margin is investigated. The estimates are found by perturbing the system with a small signal and then correlating the system deviation with the excitation. As only two parameters are estimated, the algorithm is robust. Moreover, the estimator can be applied to non-minimum phase systems, including systems with a varying time-delay. The control algorithm can be of any form as long as there is a functional relationship between the estimated parameters and the control algorithm parameters. To avoid an excessive perturbation signal, the square of the amplitude of this signal is automatically adjusted to a certain ratio of the variance of the error signal. A mathematical analysis of convergence is presented and the theory is confirmed by experimental results.

  8. Closing the loop from continuous M-health monitoring to fuzzy logic-based optimized recommendations.

    Science.gov (United States)

    Benharref, Abdelghani; Serhani, Mohamed Adel; Nujum, Al Ramzana

    2014-01-01

    Continuous sensing of health metrics might generate a massive amount of data. Generating clinically validated recommendations, out of these data, to patients under monitoring is of prime importance to protect them from risk of falling into severe health degradation. Physicians also can be supported with automated recommendations that gain from historical data and increasing learning cycles. In this paper, we propose a Fuzzy Expert System that relies on data collected from continuous monitoring. The monitoring scheme implements preprocessing of data for better data analytics. However, data analytics implements the loopback feature in order to constantly improve fuzzy rules, knowledge base, and generated recommendations. Both techniques reduced data quantity, improved data quality and proposed recommendations. We evaluate our solution through a series of experiments and the results we have obtained proved that our fuzzy expert system combined with the intelligent monitoring and analytic techniques provide a high accuracy of collected data and valid advices.

  9. Modeling of sorption enhanced steam methane reforming—Part II: Simulation within a novel Ca/Cu chemical loop process for hydrogen production

    OpenAIRE

    Fernández García, José Ramón; Abanades García, Juan Carlos; Grasa Adiego, Gemma

    2012-01-01

    The initial stage of a novel Ca/Cu looping process for hydrogen production that involves the sorption enhanced reforming of methane (SER) at high pressure and at a moderate temperature is simulated using a mathematical model developed in Part I of this work. The SER reaction step has been analyzed under dynamic conditions within the framework of the following reactor parameters and operation conditions: catalyst/sorbent ratio, space time, operating temperature, operating pressure and steam/ca...

  10. Development of PLC based control system for frequency tuning loop of 31.6 MHz RF cavity

    International Nuclear Information System (INIS)

    Two storage rings, Indus-1 and Indus-2 are operational at RRCAT. Both the storage rings share a common injector system consisting of a Microtron and a Booster Synchrotron. The electrons are generated and accelerated to 20 MeV in Microtron and injected through a transfer line into the Booster Synchrotron where its energy is increased to 450 MeV/550 MeV. In Booster Synchrotron, a MHz RF system is installed. This RF System includes 1 kW RF amplifier, re-entrant type RF cavity and its tuning system. The RF system works in ramp mode. In RF cavities, resonant frequency changes due to beam loading and temperature effect. Our aim is to keep the RF Cavity at fixed resonance. Frequency Tuning Loop (FTL) will keep the cavities tuned by compensating for both beam loading and temperature effects. This is realized by means of a mechanism, driven by a stepper motor, which changes the volume of RF cavity by moving the plunger in/out and therefore its frequency. A Programmable Logic Controller (PLC) based Control system was developed to replace existing control system for FTL of RF Cavity installed in Booster Synchrotron. The main components of the control system are the phase detector, PLC with analog module, optical isolation card and touch screen interface. Control logic was developed in Step-7 MicroWin. The complete control logic, advantages over the earlier control system and scope for adaptability has been thoroughly discussed in this paper

  11. Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

    Institute of Scientific and Technical Information of China (English)

    Huang Hao; Pan Minghai; Lu Zhijun

    2015-01-01

    Hardware-in-the-loop (HWIL) simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting sig-nal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory (DRFM) system, the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile (HRRP) are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.

  12. Development and evaluation of a novel and rapid detection assay for Botrytis cinerea based on loop-mediated isothermal amplification.

    Directory of Open Access Journals (Sweden)

    Ya-Bing Duan

    Full Text Available Botrytis cinerea is a devastating plant pathogen that causes grey mould disease. In this study, we developed a visual detection method of B. cinerea based on the Bcos5 sequence using loop-mediated isothermal amplification (LAMP with hydroxynaphthol blue dye (HNB. The LAMP reaction was optimal at 63 °C for 45 min. When HNB was added prior to amplification, samples with B. cinerea DNA developed a characteristic sky blue color after the reaction but those without DNA or with DNA of other plant pathogenic fungi did not. Results of HNB staining method were reconfirmed when LAMP products were subjected to gel electrophoresis. The detection limit of this LAMP assay for B. cinerea was 10(-3 ng µL(-1 of genomic DNA per reaction, which was 10-fold more sensitive than conventional PCR (10(-2 ng µL(-1. Detection of the LAMP assay for inoculum of B. cinerea was possible in the inoculated tomato and strawberry petals. In the 191 diseased samples, 180 (94.2% were confirmed as positive by LAMP, 172 (90.1% positive by the tissue separation, while 147 (77.0% positive by PCR. Because the LAMP assay performed well in aspects of sensitivity, specificity, repeatability, reliability, and visibility, it is suitable for rapid detection of B. cinerea in infected plant materials prior to storage and during transportation, such as cut flowers, fruits and vegetables.

  13. Detection of Puccinia kuehnii Causing Sugarcane Orange Rust with a Loop-Mediated Isothermal Amplification-Based Assay.

    Science.gov (United States)

    Chandra, Amaresh; Keizerweerd, Amber T; Grisham, Michael P

    2016-03-01

    Puccinia kuehnii is a fungal pathogen that causes orange rust in sugarcane, which is now prevalent in many countries. At the early stage of disease, it is almost indistinguishable from brown rust, which is caused by Puccinia melanocephala. Although several PCR assays are available to detect these diseases, the loop-mediated isothermal amplification (LAMP)-based assay has been reported to be more economical and easier to perform. Under isothermal conditions, DNA is amplified with high specificity and rapidity. Moreover, visual judgment of color change without further post-amplification processing makes the method convenient. The present study was undertaken to detect P. kuehnii genomic DNA using four primers corresponding to a unique DNA sequence of P. kuehnii. The LAMP assay was found to be optimal when 8 mM MgSO4 was used and the reaction was incubated at 63 °C for 90 min. Positive samples showed a color change from orange to green upon SYBR Green I dye addition. Specificity of the LAMP test was checked with DNA of P. melanocephala, which showed no reaction. Sensitivity of the LAMP method was observed to be the same as real-time PCR at 0.1 ng, thus providing a rapid and more affordable option for early disease detection. PMID:26837389

  14. A sapphire fibre thermal probe based on fast Fourier transform and phase-lock loop

    Institute of Scientific and Technical Information of China (English)

    Wang Yu-Tian; Wang Dong-Sheng; Ge Wen-Qian; Cui Li-Chao

    2006-01-01

    A sapphire fibre thermal probe with Cra+ ion-doped end is developed by using the laser heated pedestal growth method. The fluorescence thermal probe offers advantages of compact structure, high performance and ability to withstand high temperature in a detection range from room temperature to 450℃. Based on the fast Fourier transform(FFT), the fluorescence lifetime is obtained from the tangent function of phase angle of the non-zeroth terms in the FFT result. This method has advantages such as quick calculation, high accuracy and immunity to the background noise. This FFT method is compared with other traditional fitting methods, indicating that the standard deviation of the FFT method is about half of that of the Prony method and about 1/6 of that of the log-fit method. And the FFT method is immune to the background noise involved in a signal. So, the FFT method is an excellent way of processing signals. In addition, a phase-lock amplifier can effectively suppress the noise.

  15. Rollercoaster loop shapes

    Science.gov (United States)

    Pendrill, Ann-Marie

    2005-11-01

    Many modern rollercoasters feature loops. Although textbook loops are often circular, real rollercoaster loops are not. In this paper, we look into the mathematical description of various possible loop shapes, as well as their riding properties. We also discuss how a study of loop shapes can be used in physics education.

  16. All-optical NOT and XOR logic operation at 2.5 Gb/s based on semiconductor optical amplifier loop mirror

    Institute of Scientific and Technical Information of China (English)

    Wang Ying; Zhang Xin-Liang; Huang De-Xiu

    2004-01-01

    All-optical XOR and NOT logic operations based on semiconductor optical amplifier loop mirror (SLALOM) are simultaneously demonstrated theoretically and experimentally. Based on a segmented semiconductor optical amplifier model, the all-optical logic operation process is simulated theoretically. In an experimental study, 2.5 Gb/s all-optical XOR operation was achieved in the output port of SLALOM, while all-optical NOT operation was achieved in the input port through a circulator at the same time.

  17. Loops: Twisting and Scaling

    Science.gov (United States)

    Walsh, R. W.

    2004-01-01

    Loop-like structures are the fundamental magnetic building blocks of the solar atmosphere. Recent space-based EUV and X-ray satellite observations (from Yohkoh SOHO and TRACE) have challenged the view that these features are simply static gravitationally stratified plasma pipes. Rather it is now surmised that each loop may consist of a bundle of fine plasma threads that are twisted around one another and can brighten independently. This invited review will outline the latest developments in ""untangling"" the topology of these features through three dimensional magnetohydrodynamic modelling and how their properties are being deduced through spectroscopic observations coupled to theoretical scaling laws. In particular recent interest has centred on how the observed thermal profile along loops can be employed as a tool to diagnose any localised energy input to the structure and hence constrain the presence of a particular coronal heating mechanism. The dynamic nature of loops will be highlighted and the implications of superior resolution plasma thread observations (whether spatial temporal or spectral) from future space missions (SolarB STEREO SDO and Solar Orbiter) will be discussed.

  18. RCD+: Fast loop modeling server.

    Science.gov (United States)

    López-Blanco, José Ramón; Canosa-Valls, Alejandro Jesús; Li, Yaohang; Chacón, Pablo

    2016-07-01

    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. PMID:27151199

  19. Predictive spectroscopy and chemical imaging based on novel optical systems

    Science.gov (United States)

    Nelson, Matthew Paul

    1998-10-01

    This thesis describes two futuristic optical systems designed to surpass contemporary spectroscopic methods for predictive spectroscopy and chemical imaging. These systems are advantageous to current techniques in a number of ways including lower cost, enhanced portability, shorter analysis time, and improved S/N. First, a novel optical approach to predicting chemical and physical properties based on principal component analysis (PCA) is proposed and evaluated. A regression vector produced by PCA is designed into the structure of a set of paired optical filters. Light passing through the paired filters produces an analog detector signal directly proportional to the chemical/physical property for which the regression vector was designed. Second, a novel optical system is described which takes a single-shot approach to chemical imaging with high spectroscopic resolution using a dimension-reduction fiber-optic array. Images are focused onto a two- dimensional matrix of optical fibers which are drawn into a linear distal array with specific ordering. The distal end is imaged with a spectrograph equipped with an ICCD camera for spectral analysis. Software is used to extract the spatial/spectral information contained in the ICCD images and deconvolute them into wave length-specific reconstructed images or position-specific spectra which span a multi-wavelength space. This thesis includes a description of the fabrication of two dimension-reduction arrays as well as an evaluation of the system for spatial and spectral resolution, throughput, image brightness, resolving power, depth of focus, and channel cross-talk. PCA is performed on the images by treating rows of the ICCD images as spectra and plotting the scores of each PC as a function of reconstruction position. In addition, iterative target transformation factor analysis (ITTFA) is performed on the spectroscopic images to generate ``true'' chemical maps of samples. Univariate zero-order images, univariate first

  20. Chemical sensors based on molecularly modified metallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Haick, Hossam [Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 32000 (Israel)

    2007-12-07

    This paper presents a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to the use of molecularly modified metal nanoparticles in or as chemical sensors. This paper attempts to pull together different views and terminologies used in sensors based on molecularly modified metal nanoparticles, including those established upon electrochemical, optical, surface Plasmon resonance, piezoelectric and electrical transduction approaches. Finally, this paper discusses briefly the main advantages and disadvantages of each of the presented class of sensors. (review article)

  1. Modified Smith Predictor Based Control Of Cascaded Chemical Reactor

    Directory of Open Access Journals (Sweden)

    Binu P. Mathew

    2014-04-01

    Full Text Available A cascade control with modified smith predictor is used for controlling an open loop unstable time delay process. It has three controllers, one is for servo response other two are for regulatory response. For two disturbance rejection controllers an analytical design method is used by proposing closed loop complementary sensitivity function. These two controllers are PID controller cascaded with second order lead/lag filter. Setpoint tracking controller is designed by using direct synthesis method. The main advantage of this control scheme is that the servo response can be decoupled from the regulatory response.

  2. Lattice Loop Quantum Gravity

    OpenAIRE

    Aastrup, Johannes; Grimstrup, Jesper M.

    2009-01-01

    We present a separable version of Loop Quantum Gravity (LQG) based on an inductive system of cubic lattices. We construct semi-classical states for which the LQG operators -- the flux, the area and the volume operators -- have the right classical limits. Also, we present the Hamilton and diffeomorphism constraints as operator constraints and show that they have the right classical limit. Finally, we speculate whether the continuum limit, which these semi-classical states probe, can be defined...

  3. 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

  4. Carbon Nanotube Based Chemical Sensors for Space and Terrestrial Applications

    Science.gov (United States)

    Li, Jing; Lu, Yijiang

    2009-01-01

    A nanosensor technology has been developed using nanostructures, such as single walled carbon nanotubes (SWNTs), on a pair of interdigitated electrodes (IDE) processed with a silicon-based microfabrication and micromachining technique. The IDE fingers were fabricated using photolithography and thin film metallization techniques. Both in-situ growth of nanostructure materials and casting of the nanostructure dispersions were used to make chemical sensing devices. These sensors have been exposed to nitrogen dioxide, acetone, benzene, nitrotoluene, chlorine, and ammonia in the concentration range of ppm to ppb at room temperature. The electronic molecular sensing of carbon nanotubes in our sensor platform can be understood by intra- and inter-tube electron modulation in terms of charge transfer mechanisms. As a result of the charge transfer, the conductance of p-type or hole-richer SWNTs in air will change. Due to the large surface area, low surface energy barrier and high thermal and mechanical stability, nanostructured chemical sensors potentially can offer higher sensitivity, lower power consumption and better robustness than the state-of-the-art systems, which make them more attractive for defense and space applications. Combined with MEMS technology, light weight and compact size sensors can be made in wafer scale with low cost. Additionally, a wireless capability of such a sensor chip can be used for networked mobile and fixed-site detection and warning systems for military bases, facilities and battlefield areas.

  5. Photonic crystal fiber based chloride chemical sensors for corrosion monitoring

    Science.gov (United States)

    Wei, Heming; Tao, Chuanyi; Krishnaswamy, Sridhar

    2016-04-01

    Corrosion of steel is one of the most important durability issues in reinforced concrete (RC) structures because aggressive ions such as chloride ions permeate concrete and corrode steel, consequently accelerating the destruction of structures, especially in marine environments. There are many practical methods for corrosion monitoring in RC structures, mostly focusing on electrochemical-based sensors for monitoring the chloride ion which is thought as one of the most important factors resulting in steel corrosion. In this work, we report a fiber-optic chloride chemical sensor based on long period gratings inscribed in a photonic crystal fiber (PCF) with a chloride sensitive thin film. Numerical simulation is performed to determine the characteristics and resonance spectral response versus the refractive indices of the analyte solution flowing through into the holes in the PCF. The effective refractive index of the cladding mode of the LPGs changes with variations of the analyte solution concentration, resulting in a shift of the resonance wavelength, hence providing the sensor signal. This fiber-optic chemical sensor has a fast response, is easy to prepare and is not susceptible to electromagnetic environment, and can therefore be of use for structural health monitoring of RC structures subjected to such aggressive environments.

  6. Modelling Amperometric Biosensors Based on Chemically Modified Electrodes

    Science.gov (United States)

    Baronas, Romas; Kulys, Juozas

    2008-01-01

    The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion layer. In order to define the main governing parameters the corresponding dimensionless mathematical model was derived. The digital simulation was carried out using the finite difference technique. The adequacy of the model was evaluated using analytical solutions known for very specific cases of the model parameters. By changing model parameters the output results were numerically analyzed at transition and steady state conditions. The influence of the substrate and mediator concentrations as well as of the thicknesses of the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially when the biosensor acts under a mixed limitation of the diffusion and the enzyme interaction with the substrate.

  7. Zirconia-based solid state chemical gas sensors

    CERN Document Server

    Zhuiykov, S

    2000-01-01

    This paper presents an overview of chemical gas sensors, based on solid state technology, that are sensitive to environmental gases, such as O sub 2 , SO sub x , NO sub x , CO sub 2 and hydrocarbons. The paper is focussed on performance of electrochemical gas sensors that are based on zirconia as a solid electrolyte. The paper considers sensor structures and selection of electrode materials. Impact of interfaces on sensor performance is discussed. This paper also provides a brief overview of electrochemical properties of zirconia and their effect on sensor performance. Impact of auxiliary materials on sensors performance characteristics, such as sensitivity, selectivity, response time and recovery time, is also discussed. Dual gas sensors that can be applied for simultaneous monitoring of the concentration of both oxygen and other gas phase components, are briefly considered

  8. The contrasting structures of mismatched DNA sequences containing looped-out bases (bulges) and multiple mismatches (bubbles).

    Science.gov (United States)

    Bhattacharyya, A; Lilley, D M

    1989-09-12

    We have studied the structure and reactivities of two kinds of mismatched DNA sequences--unopposed bases, or bulges, and multiple mismatched pairs of bases. These were generated in a constant sequence environment, in relatively long DNA fragments, using a technique based on heteroduplex formation between sequences cloned into single-stranded M13 phage. The mismatched sequences were studied from two points of view, viz 1. The mobility of the fragments on gel electrophoresis in polyacrylamide was studied in order to examine possible bending of the DNA due to the presence of the mismatch defect. Such bending would constitute a global effect on the conformation of the molecule. 2. Sequences in and around the mismatches were studied using enzyme and chemical probes of DNA structure. This would reveal more local structural effects of the mismatched sequences. We observed that the structures of the bulges and the multiple mismatches appear to be fundamentally different. The bulged sequences exhibited a large gel retardation, consistent with a significant bending of the DNA at the bulge, and whose magnitude depends on the number of mismatched bases. The larger bulges were sensitive to cleavage by single-strand specific nucleases, and modified by diethyl pyrocarbonate (adenines) or osmium tetroxide (thymines) in a non-uniform way, suggesting that the bulges have a precise structure that leads to exposure of some, but not all, of the bases. In contrast the multiple mismatches ('bubbles') cause very much less bending of the DNA fragment in which they occur, and uniform patterns of chemical reactivity along the length of the mismatched sequences, suggesting a less well defined, and possibly flexible, structure. The precise structure of the bulges suggests that such features may be especially significant for recognition by proteins.

  9. Gene expression module-based chemical function similarity search

    OpenAIRE

    Li, Yun; Hao, Pei; Zheng, Siyuan; Tu, Kang; Fan, Haiwei; Zhu, Ruixin; Ding, Guohui; Dong, Changzheng; Wang, Chuan; Li, Xuan; Thiesen, H.-J.; Chen, Y. Eugene; Jiang, HuaLiang; Liu, Lei; Li, Yixue

    2008-01-01

    Investigation of biological processes using selective chemical interventions is generally applied in biomedical research and drug discovery. Many studies of this kind make use of gene expression experiments to explore cellular responses to chemical interventions. Recently, some research groups constructed libraries of chemical related expression profiles, and introduced similarity comparison into chemical induced transcriptome analysis. Resembling sequence similarity alignment, expression pat...

  10. BMN correlators by loop equations

    International Nuclear Information System (INIS)

    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)

  11. Novel tracking loop of BOC signal based on subcarrier tracking%基于副载波跟踪的BOC信号跟踪环路设计

    Institute of Scientific and Technical Information of China (English)

    杨再秀; 黄智刚; 耿生群

    2011-01-01

    针对二进制偏移载波(BOC,Binary Offset Carrier)调制信号跟踪的模糊性问题,提出了一种新的基于副载波跟踪的环路结构.通过增加副载波跟踪模块,对副载波和扩频码进行分离跟踪,解决了BOC信号跟踪的模糊性问题;针对副载波信号周期性的特点,以正弦波作为本地信号,利用锁相环实现对副载波的稳定跟踪.通过软件仿真,分析对比了该环路的码跟踪误差、跟踪门限和平均失锁时间(MTLL,Mean Time to Lose Lock)等性能指标.结果表明,新的环路结构能在保证跟踪精度的前提下,提高对弱信号的跟踪性能,具有较高的环路稳定性.%In order to eliminate the tracking ambiguity of binary offset carrier ( BOG ) signal, a novel tracking loop based on subcarrier tracking was proposed. Compared with traditional tracking loop, the proposed architecture provides a subcarrier locked loop to track subcarrier. The innovative tracking loop architecture resolves the tracking ambiguity problem by tracking the subcarrier and spread spectrum code respectively.The subcarrier was synchronized with the local sinusoidal signal using phase lock loop (PLL), which exploits the periodic feature of the subcarrier of BOC signal. Figures of merit, such as code tracking error, tracking threshold and mean time to lose lock (MTLL) have been analyzed and evaluated through software simulations.Simulation results show that the novel tracking loop can improve the tracking performance of weak signal and enhance the tracking loop stability with little degradation in tracking accuracy.

  12. 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

  13. Modified Projective Synchronization between Different Fractional-Order Systems Based on Open-Plus-Closed-Loop Control and Its Application in Image Encryption

    OpenAIRE

    Hongjuan Liu; Zhiliang Zhu; Hai Yu; Qian Zhu

    2014-01-01

    A new general and systematic coupling scheme is developed to achieve the modified projective synchronization (MPS) of different fractional-order systems under parameter mismatch via the Open-Plus-Closed-Loop (OPCL) control. Based on the stability theorem of linear fractional-order systems, some sufficient conditions for MPS are proposed. Two groups of numerical simulations on the incommensurate fraction-order system and commensurate fraction-order system are presented to justify the theoretic...

  14. Graphene-Based Chemical Vapor Sensors for Electronic Nose Applications

    Science.gov (United States)

    Nallon, Eric C.

    chemiresistor device and used as a chemical sensor, where its resistance is temporarily modified while exposed to chemical compounds. The inherent, broad selective nature of graphene is demonstrated by testing a sensor against a diverse set of volatile organic compounds and also against a set of chemically similar compounds. The sensor exhibits excellent selectivity and is capable of achieving high classification accuracies. The kinetics of the sensor's response are further investigated revealing a relationship between the transient behavior of the response curve and physiochemical properties of the compounds, such as the molar mass and vapor pressure. This kinetic information is also shown to provide important information for further pattern recognition and classification, which is demonstrated by increased classification accuracy of very similar compounds. Covalent modification of the graphene surface is demonstrated by means of plasma treatment and free radical exchange, and sensing performance compared to an unmodified graphene sensor. Finally, the first example of a graphene-based, cross-reactive chemical sensor array is demonstrated by applying various polymers as coatings over an array of graphene sensors. The sensor array is tested against a variety of compounds, including the complex odor of Scotch whiskies, where it is capable of perfect classification of 10 Scotch whiskey variations.

  15. How to Generate Chaos from Switching System: A Saddle Focus of Index 1 and Heteroclinic Loop-Based Approach

    Directory of Open Access Journals (Sweden)

    Fang Bao

    2011-01-01

    Full Text Available There exist two different types of equilibrium points in 3-D autonomous systems, named as saddle foci of index 1 and index 2, which are crucial for chaos generation. Although saddle foci of index 2 have been usually applied for creating double-scroll or double-wing chaotic attractors, saddle foci of index 1 are further considered for chaos generation in this paper. A novel approach for constructing chaotic systems is investigated by applying the switching control strategy and yielding a heteroclinic loop which connects two saddle foci of index 1. A basic 3-D linear system with an arbitrary normal direction of the eigenplane, possessing a saddle focus of index 1 whose corresponding eigenvalues satisfy the Shil'nikov inequality, is first introduced. Then a heteroclinic loop connecting two saddle foci of index 1 will be formed by applying the switching control strategy to the basic 3-D linear system. The heteroclinic loop consists of an unstable manifold, a stable manifold, and a heteroclinic point. Under the necessary conditions for forming the heteroclinic loop, the intended two-segmented piecewise linear system which exhibits the chaotic behavior in the sense of the Smale horseshoe can be finally constructed. An illustrative example is given, confirming the effectiveness of the proposed method.

  16. Mechanism-based bioanalysis and biomarkers for hepatic chemical stress.

    Science.gov (United States)

    Antoine, D J; Mercer, A E; Williams, D P; Park, B K

    2009-08-01

    Adverse drug reactions, in particular drug-induced hepatotoxicity, represent a major challenge for clinicians and an impediment to safe drug development. Novel blood or urinary biomarkers of chemically-induced hepatic stress also hold great potential to provide information about pathways leading to cell death within tissues. The earlier pre-clinical identification of potential hepatotoxins and non-invasive diagnosis of susceptible patients, prior to overt liver disease is an important goal. Moreover, the identification, validation and qualification of biomarkers that have in vitro, in vivo and clinical transferability can assist bridging studies and accelerate the pace of drug development. Drug-induced chemical stress is a multi-factorial process, the kinetics of the interaction between the hepatotoxin and the cellular macromolecules are crucially important as different biomarkers will appear over time. The sensitivity of the bioanalytical techniques used to detect biological and chemical biomarkers underpins the usefulness of the marker in question. An integrated analysis of the biochemical, molecular and cellular events provides an understanding of biological (host) factors which ultimately determine the balance between xenobiotic detoxification, adaptation and liver injury. The aim of this review is to summarise the potential of novel mechanism-based biomarkers of hepatic stress which provide information to connect the intracellular events (drug metabolism, organelle, cell and whole organ) ultimately leading to tissue damage (apoptosis, necrosis and inflammation). These biomarkers can provide both the means to inform the pharmacologist and chemist with respect to safe drug design, and provide clinicians with valuable tools for patient monitoring. PMID:19621999

  17. Chemistry research and chemical techniques based on research reactors

    International Nuclear Information System (INIS)

    Chemistry has occupied an important position historically in the sciences associated with nuclear reactors and it continues to play a prominent role in reactor-based research investigations. This Panel of prominent scientists in the field was convened by the International Atomic Energy Agency (IAEA) to assess the present state of such chemistry research for the information of its Member States and others interested in the subject. There are two ways in which chemistry is associated with nuclear reactors: (a) general applications to many scientific fields in which chemical techniques are involved as essential service functions; and (b) specific applications of reactor facilities to the solution of chemical problems themselves. Twenty years of basic research with nuclear reactors have demonstrated a very widespread, and still increasing, demand for radioisotopes and isotopically-labelled molecules in all fields of the physical and biological sciences. Similarly, the determination of the elemental composition of a material through the analytical technique of activation analysis can be applied throughout experimental science. Refs, figs and tabs

  18. Chemical Signaling and Functional Activation in Colloidosome-Based Protocells.

    Science.gov (United States)

    Sun, Shiyong; Li, Mei; Dong, Faqin; Wang, Shengjie; Tian, Liangfei; Mann, Stephen

    2016-04-01

    An aqueous-based microcompartmentalized model involving the integration of partially hydrophobic Fe(III)-rich montmorillonite (FeM) clay particles as structural and catalytic building blocks for colloidosome membrane assembly, self-directed membrane remodeling, and signal-induced protocell communication is described. The clay colloidosomes exhibit size- and charge-selective permeability, and show dual catalytic functions involving spatially confined enzyme-mediated dephosphorylation and peroxidase-like membrane activity. The latter is used for the colloidosome-mediated synthesis and assembly of a temperature-responsive poly(N-isopropylacrylamide)(PNIPAM)/clay-integrated hybrid membrane. In situ PNIPAM elaboration of the membrane is coupled to a glucose oxidase (GOx)-mediated signaling pathway to establish a primitive model of chemical communication and functional activation within a synthetic "protocell community" comprising a mixed population of GOx-containing silica colloidosomes and alkaline phosphatase (ALP)-containing FeM-clay colloidosomes. Triggering the enzyme reaction in the silica colloidosomes gives a hydrogen peroxide signal that induces polymer wall formation in a coexistent population of the FeM-clay colloidosomes, which in turn generates self-regulated membrane-gated ALP-activity within the clay microcompartments. The emergence of new functionalities in inorganic colloidosomes via chemical communication between different protocell populations provides a first step toward the realization of interacting communities of synthetic functional microcompartments. PMID:26923794

  19. Application of Physiologically Based Pharmacokinetic Models in Chemical Risk Assessment

    Directory of Open Access Journals (Sweden)

    Moiz Mumtaz

    2012-01-01

    Full Text Available Post-exposure risk assessment of chemical and environmental stressors is a public health challenge. Linking exposure to health outcomes is a 4-step process: exposure assessment, hazard identification, dose response assessment, and risk characterization. This process is increasingly adopting “in silico” tools such as physiologically based pharmacokinetic (PBPK models to fine-tune exposure assessments and determine internal doses in target organs/tissues. Many excellent PBPK models have been developed. But most, because of their scientific sophistication, have found limited field application—health assessors rarely use them. Over the years, government agencies, stakeholders/partners, and the scientific community have attempted to use these models or their underlying principles in combination with other practical procedures. During the past two decades, through cooperative agreements and contracts at several research and higher education institutions, ATSDR funded translational research has encouraged the use of various types of models. Such collaborative efforts have led to the development and use of transparent and user-friendly models. The “human PBPK model toolkit” is one such project. While not necessarily state of the art, this toolkit is sufficiently accurate for screening purposes. Highlighted in this paper are some selected examples of environmental and occupational exposure assessments of chemicals and their mixtures.

  20. A Solar-Hybrid Power Plant Integrated With Ethanol Chemical-Looping Combustion%低温太阳热与乙醇化学链燃烧的系统研究

    Institute of Scientific and Technical Information of China (English)

    潘莹; 韩涛; 洪慧; 金红光

    2011-01-01

    In this paper, a new solar hybrid gas turbine cycle integrating ethanol-fueled chemicallooping combustion (CLC) has been proposed, and the system was investigated with the aid of the Energy-Utilization Diagram (EUD). Chemical-looping combustion consists of two successive reactions: first, ethanol fuel is oxidized by metal oxide (NiO) as an oxygen carrier (reduction of metal oxide); secondly, the reduced metal (Ni) is successively oxidized by combustion air (the oxidation of metal). The reduction of NiO with ethanol requires a relative low-grade thermal energy at 150-200℃. Then, concentrated solar thermal energy at approximately 200-300℃ can be utilized to provide the process heat for this reaction. The integration of solar thermal energy and CLC could make the exergy efficiency and the net solar-to-electric efficiency of the system more than 54% and 28% at a turbine inlet temperature (TIT) of 1288℃, respectively. The promising results obtained here indicate that this novel gas turbine cycle with ethanol-fueled chemical-looping combustion could provide a promising approach of both efficient use of alternative fuel and low-temperature solar thermal and offer a technical probability of combining the chemical-looping combustion with inherent CO2 capture for the alternative fuel.%探索并提出低温太阳热能与乙醇一氧化镍化学链燃烧相结合的新颖能量动力系统。该系统利用中低温太阳热能提供乙醇和氧化镍反应热,将低温太阳能转换为高品位化学能储存在固体金属氧化物中。基于图像[火用]分析方法,明确地指出乙醇化学链燃烧能量释放过程燃烧[火用]损失减小和低温太阳热品位提升的机理。本文对新循环进行了分析,相比常规联合循环,新系统热效率提高约8个百分点,同时可以实现CO2无能耗分离。

  1. Limiting factors for carbon based chemical double layer capacitors

    Science.gov (United States)

    Rose, M. Frank; Johnson, C.; Owens, T.; Stevens, B.

    1993-01-01

    The Chemical Double Layer (CDL) capacitor improves energy storage density dramatically when compared with conventional electrolytic capacitors. When compared to batteries, the CDL Capacitor is much less energy dense; however, the power density is orders of magnitude better. As a result, CDL-battery combinations present an interesting pulse power system with many potential applications. Due to the nature of the CDL it is inherently a low voltage device. The applications of the CDL can be tailored to auxiliary energy and burst mode storages which require fast charge/discharge cycles. Typical of the applications envisioned are power system backup, directed energy weapons concepts, electric automobiles, and electric actuators. In this paper, we will discuss some of the general characteristics of carbon-based CDL technology describing the structure, performance parameters, and methods of construction. Further, analytical and experimental results which define the state of the art are presented and described in terms of impact on applications.

  2. Evaluation of Artificial Intelligence Based Models for Chemical Biodegradability Prediction

    Directory of Open Access Journals (Sweden)

    Aleksandar Sabljic

    2004-12-01

    Full Text Available This study presents a review of biodegradability modeling efforts including a detailed assessment of two models developed using an artificial intelligence based methodology. Validation results for these models using an independent, quality reviewed database, demonstrate that the models perform well when compared to another commonly used biodegradability model, against the same data. The ability of models induced by an artificial intelligence methodology to accommodate complex interactions in detailed systems, and the demonstrated reliability of the approach evaluated by this study, indicate that the methodology may have application in broadening the scope of biodegradability models. Given adequate data for biodegradability of chemicals under environmental conditions, this may allow for the development of future models that include such things as surface interface impacts on biodegradability for example.

  3. Trends in information theory-based chemical structure codification.

    Science.gov (United States)

    Barigye, Stephen J; Marrero-Ponce, Yovani; Pérez-Giménez, Facundo; Bonchev, Danail

    2014-08-01

    This report offers a chronological review of the most relevant applications of information theory in the codification of chemical structure information, through the so-called information indices. Basically, these are derived from the analysis of the statistical patterns of molecular structure representations, which include primitive global chemical formulae, chemical graphs, or matrix representations. Finally, new approaches that attempt to go "back to the roots" of information theory, in order to integrate other information-theoretic measures in chemical structure coding are discussed.

  4. Chemical fingerprinting of silicone-based breast implants.

    Science.gov (United States)

    Keizers, Peter H J; Vredenbregt, Marjo J; Bakker, Frank; de Kaste, Dries; Venhuis, Bastiaan J

    2015-01-01

    With millions of women worldwide carrying them, silicone-based breast implants represent a large market. Even though silicone breast implants already have a history of use of more than 50 years, the discussion on their safety has not yet come to an end. To improve safety assessment, regulatory authorities should have the availability of a set of tests to be able to determine parameters of implant identity and quality. Therefore, the gels and envelopes of various brands and types of silicone-based breast implants have been subjected to infrared, Raman and NMR spectroscopy. We show that by using a combination of complementary spectroscopic techniques breast implants of various origins can be distinguished on typical chemical hallmarks. It was found that typical silicone-based implants display a surplus of vinyl signals in the gel, cyclosiloxane impurities are tolerable at low levels only and a barrier layer is present in the implant envelope. The techniques presented here and the results obtained offer a good starting point for market surveillance studies. PMID:25459933

  5. Chemical fingerprinting of silicone-based breast implants.

    Science.gov (United States)

    Keizers, Peter H J; Vredenbregt, Marjo J; Bakker, Frank; de Kaste, Dries; Venhuis, Bastiaan J

    2015-01-01

    With millions of women worldwide carrying them, silicone-based breast implants represent a large market. Even though silicone breast implants already have a history of use of more than 50 years, the discussion on their safety has not yet come to an end. To improve safety assessment, regulatory authorities should have the availability of a set of tests to be able to determine parameters of implant identity and quality. Therefore, the gels and envelopes of various brands and types of silicone-based breast implants have been subjected to infrared, Raman and NMR spectroscopy. We show that by using a combination of complementary spectroscopic techniques breast implants of various origins can be distinguished on typical chemical hallmarks. It was found that typical silicone-based implants display a surplus of vinyl signals in the gel, cyclosiloxane impurities are tolerable at low levels only and a barrier layer is present in the implant envelope. The techniques presented here and the results obtained offer a good starting point for market surveillance studies.

  6. Sequence-based polymorphisms in the mitochondrial D-loop and potential SNP predictors for chronic dialysis.

    Directory of Open Access Journals (Sweden)

    Jin-Bor Chen

    Full Text Available BACKGROUND: The mitochondrial (mt displacement loop (D-loop is known to accumulate structural alterations and mutations. The aim of this study was to investigate the prevalence of single nucleotide polymorphisms (SNPs within the D-loop among chronic dialysis patients and healthy controls. METHODOLOGY AND PRINCIPAL FINDINGS: We enrolled 193 chronic dialysis patients and 704 healthy controls. SNPs were identified by large scale D-loop sequencing and bioinformatic analysis. Chronic dialysis patients had lower body mass index, blood thiols, and cholesterol levels than controls. A total of 77 SNPs matched with the positions in reference of the Revised Cambridge Reference Sequence (CRS were found in the study population. Chronic dialysis patients had a significantly higher incidence of 9 SNPs compared to controls. These include SNP5 (16108Y, SNP17 (16172Y, SNP21 (16223Y, SNP34 (16274R, SNP35 (16278Y, SNP55 (16463R, SNP56 (16519Y, SNP64 (185R, and SNP65 (189R in D-loop of CRS. Among these SNPs with genotypes, SNP55-G, SNP56-C, and SNP64-A were 4.78, 1.47, and 5.15 times more frequent in dialysis patients compared to controls (P<0.05, respectively. When adjusting the covariates of demographics and comorbidities, SNP64-A was 5.13 times more frequent in dialysis patients compared to controls (P<0.01. Furthermore, SNP64-A was found to be 35.80, 3.48, 4.69, 5,55, and 4.67 times higher in female patients and in patients without diabetes, coronary artery disease, smoking, and hypertension in an independent significance manner (P<0.05, respectively. In patients older than 50 years or with hypertension, SNP34-A and SNP17-C were found to be 7.97 and 3.71 times more frequent (P<0.05 compared to patients younger than 50 years or those without hypertension, respectively. CONCLUSIONS AND SIGNIFICANCE: The results of large-scale sequencing suggest that specific SNPs in the mtDNA D-loop are significantly associated with chronic dialysis. These SNPs can be considered

  7. Evidence-Based Approaches to Improving Chemical Equilibrium Instruction

    Science.gov (United States)

    Davenport, Jodi L.; Leinhardt, Gaea; Greeno, James; Koedinger, Kenneth; Klahr, David; Karabinos, Michael; Yaron, David J.

    2014-01-01

    Two suggestions for instruction in chemical equilibrium are presented, along with the evidence that supports these suggestions. The first is to use diagrams to connect chemical reactions to the effects of reactions on concentrations. The second is the use of the majority and minority species (M&M) strategy to analyze chemical equilibrium…

  8. Effect of the presence of HCl on cyclic CO2 capture of calcium-based sorbent in calcium looping process

    International Nuclear Information System (INIS)

    Highlights: • HCl improves CO2 capture capacity of limestone in the previous a dozen cycles. • HCl sharply decreases limestone reactivity after a dozen cycles. • HCl intensifies effects of carbonation and calcination temperature on CO2 capture. • HCl enlarges effects of particle size on CO2 capture. • HCl severely aggravates the sintering of limestone after a dozen cycles. - Abstract: The effect of the presence of HCl on cyclic CO2 capture behavior of calcium-based sorbent in the calcium looping process was investigated. When HCl was present in the carbonation atmosphere, the effects of carbonation temperature, calcination temperature, HCl concentration and particle size on CO2 capture of the limestone in the multiple calcination/carbonation cycles were studied in a dual fixed-bed reactor. The presence of HCl in the carbonation atmosphere improves CO2 capture capacity of the limestone in the previous a dozen cycles, but sharply decreases its reactivity with further increasing the cycle number above a dozen. The presence of HCl intensifies the effects of carbonation temperature and calcination temperature on CO2 capture capacity of the limestone. The optimum carbonation temperature and the feasible calcination temperature for cyclic CO2 capture of the limestone in the presence of HCl should be 700 °C and below 900 °C, respectively. The cyclic CO2 capture capacity of the limestone in the previous a dozen cycles achieves the maximum in the presence of 300 ppm HCl with increasing the HCl concentration from 100 to 1000 ppm. The higher CO2 capture capacity of the limestone is achieved with smaller particle size in the presence of HCl. The presence of HCl may destroy the compact CaCO3 product layer and it is beneficial to CO2 diffusion through the layer in the initial cycles. The chlorination conversion and the molten CaCl2–CaCO3 product layer thickness of the limestone in the presence of HCl increase with the number of calcination/carbonation cycles. It

  9. Development of Oilfield Chemicals Based on Advantages in Petrochemical Feedstocks

    Institute of Scientific and Technical Information of China (English)

    Wang Xieqing; Peng Pu

    2002-01-01

    This article focuses on the routes for development of oilfield chemicals by making use of the feedstock advantages of the petrochemical industry. The diversification of oilfield chemicals has re sulted in thousand product grades. Because there are hundred domestic producers of oilfield chemicals,mostly medium and small producers, the fluctuations of feedstock prices and product quality cannot be conducive to the application and development of oilfield chemicals. This article illustrates the feasibility of oilfield chemical production by state-run medium and large petrochemical enterprises by allowing full play to their own advantages in petrochemical feedstocks.

  10. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure.

    Directory of Open Access Journals (Sweden)

    Bo Zhao

    Full Text Available This paper considers a decentralized fault tolerant control (DFTC scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO. Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations.

  11. A closed-loop causal model of workload based on a comparison of fuzzy and crisp measurements techniques

    Science.gov (United States)

    Moray, Neville; King, Barbara; Turksen, Burhan; Waterton, Keith

    1987-01-01

    Fuzzy and crisp measurements of workload are compared for a tracking task that varied in bandwidth and order of control. Fuzzy measures are as powerful as crisp measures, and can under certain conditions give extra insights into workload causality. Both methods suggest that workload arises in a system in which effort, performance, difficulty, and task variables are linked in a closed loop. Marked individual differences were found. Future work on the fuzzy measurement of workload is justified.

  12. MRFT-based design of robust and adaptive controllers for gas loop of oil–gas separator

    OpenAIRE

    Hamdati Al Shehhi; Igor Boiko

    2015-01-01

    The modified relay feedback test (MRFT), which was recently proposed as a continuous oscillation method for identification of the process parameters and controller tuning, is used for the design of a robust and an adaptive Proportional-Integral (PI) controller for a gas loop in the oil–gas separator. The gas normally found in the separator is the natural gas (mostly methane) which is contained in crude oil coming from the reservoir. The robust and adaptive PI controllers are developed from an...

  13. A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular Velocity Error Modeling

    OpenAIRE

    Yanshun Zhang; Yajing Guo; Chunyu Li; Yixin Wang; Zhanqing Wang

    2015-01-01

    With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage  and temperature  as the input variables and angular velocity error  as the output variable. Firstly, the angular ve...

  14. A new model based on adaptation of the external loop to compensate the hysteresis of tactile sensors.

    Science.gov (United States)

    Sánchez-Durán, José A; Vidal-Verdú, Fernando; Oballe-Peinado, Óscar; Castellanos-Ramos, Julián; Hidalgo-López, José A

    2015-10-15

    This paper presents a novel method to compensate for hysteresis nonlinearities observed in the response of a tactile sensor. The External Loop Adaptation Method (ELAM) performs a piecewise linear mapping of the experimentally measured external curves of the hysteresis loop to obtain all possible internal cycles. The optimal division of the input interval where the curve is approximated is provided by the error minimization algorithm. This process is carried out off line and provides parameters to compute the split point in real time. A different linear transformation is then performed at the left and right of this point and a more precise fitting is achieved. The models obtained with the ELAM method are compared with those obtained from three other approaches. The results show that the ELAM method achieves a more accurate fitting. Moreover, the involved mathematical operations are simpler and therefore easier to implement in devices such as Field Programmable Gate Array (FPGAs) for real time applications. Furthermore, the method needs to identify fewer parameters and requires no previous selection process of operators or functions. Finally, the method can be applied to other sensors or actuators with complex hysteresis loop shapes.

  15. A New Model Based on Adaptation of the External Loop to Compensate the Hysteresis of Tactile Sensors

    Directory of Open Access Journals (Sweden)

    José A. Sánchez-Durán

    2015-10-01

    Full Text Available This paper presents a novel method to compensate for hysteresis nonlinearities observed in the response of a tactile sensor. The External Loop Adaptation Method (ELAM performs a piecewise linear mapping of the experimentally measured external curves of the hysteresis loop to obtain all possible internal cycles. The optimal division of the input interval where the curve is approximated is provided by the error minimization algorithm. This process is carried out off line and provides parameters to compute the split point in real time. A different linear transformation is then performed at the left and right of this point and a more precise fitting is achieved. The models obtained with the ELAM method are compared with those obtained from three other approaches. The results show that the ELAM method achieves a more accurate fitting. Moreover, the involved mathematical operations are simpler and therefore easier to implement in devices such as Field Programmable Gate Array (FPGAs for real time applications. Furthermore, the method needs to identify fewer parameters and requires no previous selection process of operators or functions. Finally, the method can be applied to other sensors or actuators with complex hysteresis loop shapes.

  16. The extended loop representation of quantum gravity

    CERN Document Server

    Di Bartolo, C; Griego, J R

    1995-01-01

    A new representation of Quantum Gravity is developed. This formulation is based on an extension of the group of loops. The enlarged group, that we call the Extended Loop Group, behaves locally as an infinite dimensional Lie group. Quantum Gravity can be realized on the state space of extended loop dependent wavefunctions. The extended representation generalizes the loop representation and contains this representation as a particular case. The resulting diffeomorphism and hamiltonian constraints take a very simple form and allow to apply functional methods and simplify the loop calculus. In particular we show that the constraints are linear in the momenta. The nondegenerate solutions known in the loop representation are also solutions of the constraints in the new representation. The practical calculation advantages allows to find a new solution to the Wheeler-DeWitt equation. Moreover, the extended representation puts in a precise framework some of the regularization problems of the loop representation. We sh...

  17. Modelling Amperometric Biosensors Based on Chemically Modified Electrodes

    Directory of Open Access Journals (Sweden)

    Juozas Kulys

    2008-08-01

    Full Text Available The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion layer. In order to define the main governing parameters the corresponding dimensionless mathematical model was derived. The digital simulation was carried out using the finite difference technique. The adequacy of the model was evaluated using analytical solutions known for very specific cases of the model parameters. By changing model parameters the output results were numerically analyzed at transition and steady state conditions. The influence of the substrate and mediator concentrations as well as of the thicknesses of the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially when the biosensor acts under a mixed limitation of the diffusion and the enzyme interaction with the substrate.

  18. Comments and Remarks over Classic Linear Loop-Gain Method for Oscillator Design and Analysis. New Proposed Method Based on NDF/RRT

    Directory of Open Access Journals (Sweden)

    J. L. Jimenez-Martin

    2012-04-01

    Full Text Available Present paper describes a new method for designing oscillators based on the Normalized Determinant Function (NDF and Return Relations (RRT . First a review of the loop-gain method will be performed, showing pros, cons and including some examples for exploring wrong so- lutions provided by this method. Wrong solutions, because some conditions have to be previously fulfilled in order to obtain right ones, which will be described and finally, demonstrate that NDF analysis is necessary, including Return Relations (RRT usefulness, which in fact are related with the True Loop-Gain. Finally concluding this paper, steps for oscillator design and analysis, using the proposed NDF/RRT method will be presented, compared to wrong previous solutions pointing out new accuracy achieved on oscillation frequency and QL prediction. Also, more new examples, of plane reference oscillators (Z/Y/rho, will be added for which loop gain method application is clearly difficult or even impossible, solving them with the new proposed NDF/RRT method.

  19. Closed-Loop Control and Advisory Mode Evaluation of an Artificial Pancreatic β Cell: Use of Proportional–Integral–Derivative Equivalent Model-Based Controllers

    Science.gov (United States)

    Percival, Matthew W.; Zisser, Howard; Jovanovič, Lois; Doyle, Francis J.

    2008-01-01

    Background Using currently available technology, it is possible to apply modern control theory to produce a closed-loop artificial β cell. Novel use of established control techniques would improve glycemic control, thereby reducing the complications of diabetes. Two popular controller structures, proportional–integral–derivative (PID) and model predictive control (MPC), are compared first in a theoretical sense and then in two applications. Methods The Bergman model is transformed for use in a PID equivalent model-based controller. The internal model control (IMC) structure, which makes explicit use of the model, is compared with the PID controller structure in the transfer function domain. An MPC controller is then developed as an optimization problem with restrictions on its tuning parameters and is shown to be equivalent to an IMC controller. The controllers are tuned for equivalent performance and evaluated in a simulation study as a closed-loop controller and in an advisory mode scenario on retrospective clinical data. Results Theoretical development shows conditions under which PID and MPC controllers produce equivalent output via IMC. The simulation study showed that the single tuning parameter for the equivalent controllers relates directly to the closed-loop speed of response and robustness, an important result considering system uncertainty. The risk metric allowed easy identification of instances of inadequate control. Results of the advisory mode simulation showed that suitable tuning produces consistently appropriate delivery recommendations. Conclusion The conditions under which PID and MPC are equivalent have been derived. The MPC framework is more suitable given the extensions necessary for a fully closed-loop artificial β cell, such as consideration of controller constraints. Formulation of the control problem in risk space is attractive, as it explicitly addresses the asymmetry of the problem; this is done easily with MPC. PMID:19885240

  20. Graphene Electronic Device Based Biosensors and Chemical Sensors

    Science.gov (United States)

    Jiang, Shan

    Two-dimensional layered materials, such as graphene and MoS2, are emerging as an exciting material system for a new generation of atomically thin electronic devices. With their ultrahigh surface to volume ratio and excellent electrical properties, 2D-layered materials hold the promise for the construction of a generation of chemical and biological sensors with unprecedented sensitivity. In my PhD thesis, I mainly focus on graphene based electronic biosensors and chemical sensors. In the first part of my thesis, I demonstrated the fabrication of graphene nanomesh (GNM), which is a graphene thin film with a periodic array of holes punctuated in it. The periodic holes introduce long periphery active edges that provide a high density of functional groups (e.g. carboxylic groups) to allow for covalent grafting of specific receptor molecules for chemical and biosensor applications. After covalently functionalizing the GNM with glucose oxidase, I managed to make a novel electronic sensor which can detect glucose as well as pH change. In the following part of my thesis I demonstrate the fabrication of graphene-hemin conjugate for nitric oxide detection. The non-covalent functionalization through pi-pi stacking interaction allows reliable immobilization of hemin molecules on graphene without damaging the graphene lattice to ensure the highly sensitive and specific detection of nitric oxide. The graphene-hemin nitric oxide sensor is capable of real-time monitoring of nitric oxide concentrations, which is of central importance for probing the diverse roles of nitric oxide in neurotransmission, cardiovascular systems, and immune responses. Our studies demonstrate that the graphene-hemin sensors can respond rapidly to nitric oxide in physiological environments with sub-nanomolar sensitivity. Furthermore, in vitro studies show that the graphene-hemin sensors can be used for the detection of nitric oxide released from macrophage cells and endothelial cells, demonstrating their

  1. Bio-based C-3 Platform Chemical: Biotechnological Production and -Conversion of 3-Hydroxypropionaldehyde

    OpenAIRE

    Rezaei, Roya

    2013-01-01

    Demands for efficient, greener, economical and sustainable production of chemicals, materials and energy have led to development of industrial biotechnology as a key technology area to provide such products from bio-based raw materials from agricultural-, forestry- and related industrial residues and by-products. For the bio-based industry, it is essential to develop a number of building blocks or platform chemicals for C2-C6 chemicals and even aromatic chemicals. 3-hydroxypropionaldehyde (3H...

  2. 基于SDG图的化工过程初步设计方案的错误侦破方法%A Signed Digraphs Based Method for Detecting Inherently Unsafe Factors of Chemical Process at Conceptual Design Stage

    Institute of Scientific and Technical Information of China (English)

    王杭州; 陈丙珍; 何小荣; 邱彤; 章龙江

    2008-01-01

    Digraph-based causal models have been widely used to model the cause and effect behavior of process systems. Signed digraphs (SDG) capture the direction of the effect. It should be mentioned that there are loops in SDG generated from chemical process. From the point of the inherent operability, the worst unsafe factor is the SDG having positive loops that means any disturbance occurring within the loop will propagate through the nodes one by one and are amplified gradually, so the system may lose control, which may lead to an accident. So finding the positive loops in a SDG and treating these unsafe factors in a proper manner can improve the inherent safety of a chemical process. This article proposed a method that can detect the above-mentioned unsafe factors in the proc-ess conceptual design stage automatically through the analysis of the SDG generated from the chemical process. A case study is illustrated to show the working of the algorithm, and then a complicated case from industry is studied to depict the effectiveness of the proposed algorithm.

  3. Reference field effect transistor based on chemically modified ISFETs

    NARCIS (Netherlands)

    Skowronska-Ptasinska, Maria; Wal, van der Peter D.; Berg, van den Albert; Bergveld, Piet; Sudhölter, Ernst J.R.; Reinhoudt, David N.

    1990-01-01

    Different hydrophobic polymers were used for chemical modification of ion-sensitive field effect transistors (ISFETs) in order to prepare a reference FET (REFET). Chemical attachment of the polymer to the ISFET gate results in a long lifetime of the device. Properties of polyacrylate (polyACE) REFET

  4. Inverse Kinematics and Control of a 7-DOF Redundant Manipulator Based on the Closed-Loop Algorithm

    Directory of Open Access Journals (Sweden)

    Jingguo Wang

    2011-01-01

    Full Text Available Closed-loop inverse kinematics (CLIK algorithm mostly resolves the redundancy at the velocity level. In this paper we extend the CLIK algorithm to the acceleration level to meet some applications that require the joint accelerations. The redundancy resolutions at the velocities and acceleration levels via pseudoinverse method are analyzed respectively. The objective function of joint limits avoidance (JLA is combined into the redundancy resolution as an optimization approach of the null space motion. A seven-DOF redundant manipulator is designed to do the computer simulations and the real experiments are carried out on a Powercube modular manipulator. Their results demonstrated the effectiveness of the proposed algorithm.

  5. Empirical potential simulations of interstitial dislocation loops in uranium dioxide

    Science.gov (United States)

    Le Prioux, Arno; Fossati, Paul; Maillard, Serge; Jourdan, Thomas; Maugis, Philippe

    2016-10-01

    Stoichiometric circular shaped interstitial dislocation loop energies are calculated in stoichiometric UO2 by empirical potential simulation. The Burgers vector directions studied are and . The main structural properties of each type of interstitial dislocation loop are determined, including stacking fault energy. Defect energies are compared and a maximum size for stable dislocation loops before transition to dislocation loops is given. A model of dislocation loop energy based on elasticity theory is then fitted on the basis of these simulation results.

  6. Chemical looping technology and its applications in fossil fuel conversion and CO2 capture%化学链技术及其在化石能源转化与二氧化碳捕集领域的应用

    Institute of Scientific and Technical Information of China (English)

    曾亮; 罗四维; 李繁星; 范良士

    2012-01-01

    Chemical looping is a reaction scheme to decompose one reaction into multiple subreactions via chemical intermediates. The concept of chemical looping has been applied to the generation of hydrogen through the steam iron reaction, as well as the production of carbon dioxide since the 20th Century. However, there are currently no chemical looping processes in commercial operation. Under the circumstances of growing global warming and energy crisis, chemical looping processes have attracted extensive interests for the unique ability to convert carbonaceous fuel to energy or chemicals with affordable CO2 control. Recent developments in chemical looping technology have overcome some of the earlier shortcomings. New research on direct conversion of solid feedstock, such as coal has also been conducted. Through the current sub-pilot/pilot scale tests and process analysis, it has been demonstrated that chemical looping process can effectively reduce the energy cost for CO2 separation with enhanced energy efficiency. This paper presents the status of existing research activities on chemical looping development for fossil fuel conversion, with emphasis on large scale demonstration of chemical looping combustion (CLC) and chemical looping gasification (CLG). The opportunities as well as the challenges on the way to commercialize chemical looping processes have also been briefly discussed.%化学链是指将某一特定的化学反应通过化学介质的作用分多步反应完成的过程.这一概念在20世纪初就曾被用于以水蒸气与铁反应制备氢气,并于20世纪中期被提出用于二氧化碳的商业化生产.然而,时至今日,尚无商业化的化学链工艺用于化石燃料的转化.在近年来全球气候变暖及能源危机的急迫形势下,化学链循环过程由于其具有可以将碳基燃料直接转化为可供封存的二氧化碳的独特能力而格外受到关注,人们因而加大了对化学链工艺的研究开发力度.现代

  7. 10 and 20 Gb/s all-optical RZ to NRZ modulation format and wavelength converter based on nonlinear optical loop mirror

    OpenAIRE

    Honzátko, P. (Pavel); Karásek, M. (Miroslav)

    2010-01-01

    We present experimental and theoretical results on all-optical 10 and 20 Gb/s RZ to NRZ modulation format and wavelength converter based on a nonlinear optical loop mirror (NOLM). A vector model of converter was developed and the shape of converted pulses was found analytically for particular choice of polarization states. In the experiment, non-zero dispersion shifted fiber with a length 1200 m was used as a nonlinear medium. Pulses from a 10 GHz mode-locked semiconductor laser diode were mo...

  8. A 1.97 μm multiwavelength thulium-doped silica fiber laser based on a nonlinear amplifier loop mirror

    International Nuclear Information System (INIS)

    A 1.97 μm multiwavelength Tm-doped fiber laser based on a nonlinear amplifier loop mirror (NALM) has been experimentally demonstrated. The NALM with 500 m standard single mode fiber introduces intensity-dependent gain to alleviate mode competition caused by homogeneous gain broadening in Tm-doped fibers. At room temperature, up to 42 wavelengths with a wavelength spacing of 0.33 nm oscillate within a 10-dB bandwidth simultaneously. Repeat measurement of the laser spectrum shows the wavelength drift of a multiwavelength Tm-doped fiber laser is less than 0.05 nm in 40 min. (letter)

  9. Multiple-Complex Coefficient-Filter-Based Phase-Locked Loop and Synchronization Technique for Three-phase Grid-Interfaced Converters in Distributed Utility Networks

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Wu, Weiyang; Chen, Zhe

    2011-01-01

    Synchronization with the utility networks is crucial for operating three-phase grid-interfaced converters. A challenge of synchronization is how to fast and precisely extract the fundamental positive and negative sequences under the distorted and unbalanced conditions. Many phase-locked loop (PLL......) and synchronization techniques have been presented in the past decades. Most of them make a tradeoff between the accuracy and dynamic response under severe distorted and unbalanced conditions. In this paper, a multiple-complex coefficient-filter-based PLL is presented, and its unique feature lies in the accurate...

  10. MRFT-based design of robust and adaptive controllers for gas loop of oil–gas separator

    Directory of Open Access Journals (Sweden)

    Hamdati Al Shehhi

    2015-12-01

    Full Text Available The modified relay feedback test (MRFT, which was recently proposed as a continuous oscillation method for identification of the process parameters and controller tuning, is used for the design of a robust and an adaptive Proportional-Integral (PI controller for a gas loop in the oil–gas separator. The gas normally found in the separator is the natural gas (mostly methane which is contained in crude oil coming from the reservoir. The robust and adaptive PI controllers are developed from analysis of 64 operating modes corresponding to certain ranges of the gas inflow and liquid-level values. It is shown through the developed model and simulations that these operating modes have significant effect on the dynamics of the gas loop. Dynamic properties of the process in each mode are studied through MRFT. The controllers are designed in order to maintain the pressure during the change of the operating conditions. Performance of the designed control system is studied by simulations.

  11. Comparative Analysis of QSAR-based vs. Chemical Similarity Based Predictors of GPCRs Binding Affinity.

    Science.gov (United States)

    Luo, Man; Wang, Xiang S; Tropsha, Alexander

    2016-01-01

    Ligand based virtual screening (LBVS) approaches could be broadly divided into those relying on chemical similarity searches and those employing Quantitative Structure-Activity Relationship (QSAR) models. We have compared the predictive power of these approaches using some datasets of compounds tested against several G-Protein Coupled Receptors (GPCRs). The k-Nearest Neighbors (kNN) QSAR models were built for known ligands of each GPCR target independently, with a fraction of tested ligands for each target set aside as a validation set. The prediction accuracies of QSAR models for making active/inactive calls for compounds in both training and validation sets were compared to those achieved by the Prediction of Activity Spectra for Substances' (PASS) and the Similarity Ensemble Approach (SEA) tools both available online. Models developed with the kNN QSAR method showed the highest predictive power for almost all tested GPCR datasets. The PASS software, which incorporates multiple end-point specific QSAR models demonstrated a moderate predictive power, while SEA, a chemical similarity based approach, had the lowest prediction power. Our studies suggest that when sufficient amount of data is available to develop and rigorously validate QSAR models such models should be chosen as the preferred virtual screening tool in ligand-based computational drug discovery as compared to chemical similarity based approaches. PMID:27491652

  12. SOIL QUALITY ASSESSMENT BASED ON CHEMICAL, ENZYMATIC AND BACTERIOLOGICAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Sofia-Paulina BALAURE

    2012-01-01

    Full Text Available This study highlights the problem of soil pollution as the result of human activities. Soil pollutans may be either chemicals or biological in nature. microbial enzymatic activities are often proposed as indicators of environmental stress. The soil samples were submitted by chemical, microbiological and enzymatic analyses. Chemical analyses were been made for determinating the heavy metals. Heavy metals from the forest soil were represented by Cu, Zn, Mn, Ni, Pb, Cd and Cr. To evaluate the concentration in heavy metals from the filtrate, we used a acetylene-nitrous oxide flame atomic absorption spectrophotometry. Potential dehydrogenase activity, the only indicator of the possible sources of pollution, excluded the presence of either chemical or biological pollution. The number of bacteria involved in the biogeochemical cycle of nitrogen in the analyzed soil indicated a high efficiency regarding the mineralization of the organic residues of plant and animal origin.

  13. Property Model-based Tailor-made Design of Chemical-based Products

    DEFF Research Database (Denmark)

    Kalakul, Sawitree

    on experiment are reduced leading to faster and cheaper to market the products. The tools also help to manage the solution of product design problems, which usually require efficient handling of model-data-knowledge from different sources and at different time and size scales. The main contribution...... framework for chemical product design and analysis and its implementation as architecture for VPPD-Lab. From many test problems, eight application examples are presented to illustrate the use of the software. For two of these examples, the prediction of product properties and the use of virtual experiments...... of this project is: (1) the development of a systematic model-based framework for chemical product design; (2) its implementation as a computer-aided tool based on a specially developed architecture; (3) the creation of product design template together with their algorithms, models, tools and data for various...

  14. Polyakov loop potential at finite density

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Christian S. [Institut für Theoretische Physik, JLU Gießen, Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Fister, Leonard [Department of Mathematical Physics, National University of Ireland Maynooth, Maynooth, County Kildare (Ireland); Luecker, Jan [Institut für Theoretische Physik, JLU Gießen, Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Pawlowski, Jan M. [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung mbH, 64291 Darmstadt (Germany)

    2014-05-01

    The Polyakov loop potential serves to distinguish between the confined hadronic and the deconfined quark–gluon plasma phases of QCD. For N{sub f}=2+1 quark flavors with physical masses we determine the Polyakov loop potential at finite temperature and density and extract the location of the deconfinement transition. We find a crossover at small values of the chemical potential running into a critical end-point at μ/T>1.

  15. Polyakov loop potential at finite density

    OpenAIRE

    Fischer, Christian S.; Leonard Fister; Jan Luecker; Pawlowski, Jan M.

    2014-01-01

    The Polyakov loop potential serves to distinguish between the confined hadronic and the deconfined quark–gluon plasma phases of QCD. For Nf=2+1 quark flavors with physical masses we determine the Polyakov loop potential at finite temperature and density and extract the location of the deconfinement transition. We find a crossover at small values of the chemical potential running into a critical end-point at μ/T>1 .

  16. 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...

  17. K-loops: Loop Transformations for Reconfigurable Architectures

    NARCIS (Netherlands)

    Dragomir, O.S.

    2011-01-01

    The focus of this dissertation is on kernel loops (K-loops), which are loop nests that contain hardware mapped kernels in the loop body. In this thesis, we propose methods for improving the performance of such K-loops, by using standard loop transformations for exposing and exploiting the coarse gr

  18. Kalman Orbit Optimized Loop Tracking

    Science.gov (United States)

    Young, Lawrence E.; Meehan, Thomas K.

    2011-01-01

    Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.

  19. Regulation of apoptotic c-Jun N-terminal kinase signaling by a stabilization-based feed-forward loop.

    Science.gov (United States)

    Xu, Zhiheng; Kukekov, Nikolay V; Greene, Lloyd A

    2005-11-01

    A sequential kinase cascade culminating in activation of c-Jun N-terminal kinases (JNKs) plays a fundamental role in promoting apoptotic death in many cellular contexts. The mechanisms by which this pathway is engaged in response to apoptotic stimuli and suppressed in viable cells are largely unknown. Here, we show that apoptotic stimuli increase endogenous cellular levels of pathway components, including POSH, mixed lineage kinases (MLKs), and JNK interacting protein 1, and that this effect occurs through protein stabilization and requires the presence of POSH as well as activation of MLKs and JNKs. Our findings suggest a self-amplifying, feed-forward loop mechanism by which apoptotic stimuli promote the stabilization of JNK pathway components, thereby contributing to cell death. PMID:16260609

  20. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    Science.gov (United States)

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1988-01-01

    A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  1. Complete subsite mapping of a "loopful" GH19 chitinase from rye seeds based on its crystal structure.

    Science.gov (United States)

    Ohnuma, Takayuki; Umemoto, Naoyuki; Kondo, Kaori; Numata, Tomoyuki; Fukamizo, Tamo

    2013-08-19

    Crystallographic analysis of a mutated form of "loopful" GH19 chitinase from rye seeds a double mutant RSC-c, in which Glu67 and Trp72 are mutated to glutamine and alanine, respectively, (RSC-c-E67Q/W72A) in complex with chitin tetrasaccharide (GlcNAc)₄ revealed that the entire substrate-binding cleft was completely occupied with the sugar residues of two (GlcNAc)₄ molecules. One (GlcNAc)₄ molecule bound to subsites -4 to -1, while the other bound to subsites +1 to +4. Comparisons of the main chain conformation between liganded RSC-c-E67Q/W72A and unliganded wild type RSC-c suggested domain motion essential for catalysis. This is the first report on the complete subsite mapping of GH19 chitinase.

  2. A CCD-based fluorescence imaging system for real-time loop-mediated isothermal amplification-based rapid and sensitive detection of waterborne pathogens on microchips.

    Science.gov (United States)

    Ahmad, Farhan; Seyrig, Gregoire; Tourlousse, Dieter M; Stedtfeld, Robert D; Tiedje, James M; Hashsham, Syed A

    2011-10-01

    Rapid, sensitive, and low-cost pathogen diagnostic systems are needed for early disease diagnosis and treatment, especially in resource-limited settings. This study reports a low-cost charge-coupled device (CCD)-based fluorescence imaging system for rapid detection of waterborne pathogens by isothermal gene amplification in disposable microchips. Fluorescence imaging capability of this monochromatic CCD camera is evaluated by optimizing the gain, offset, and exposure time. This imaging system is validated for 12 virulence genes of major waterborne pathogens on cyclic olefin polymer (COP) microchips, using SYTO-82 dye and real time fluorescence loop-mediated isothermal amplification referred here as microRT(f)-LAMP. Signal-to-noise ratio (SNR) and threshold time (Tt) of microRT(f)-LAMP assays are compared with those from a commercial real-time polymerase chain reaction (PCR) instrument. Applying a CCD exposure of 5 s to 10(5) starting DNA copies of microRT(f)-LAMP assays increases the SNR by 8-fold and reduces the Tt by 9.8 min in comparison to a commercial real-time PCR instrument. Additionally, single copy level sensitivity for Campylobacter jejuni 0414 gene is obtained for microRT(f)-LAMP with a Tt of 19 min, which is half the time of the commercial real-time PCR instrument. Due to the control over the exposure time and the wide field imaging capability of CCD, this low-cost fluorescence imaging system has the potential for rapid and parallel detection of pathogenic microorganisms in high throughput microfluidic chips.

  3. Loop functions in thermal QCD

    OpenAIRE

    Vairo Antonio

    2014-01-01

    We discuss divergences of loop functions in thermal QCD and compute perturbatively the Polyakov loop, the Polyakov loop correlator and the cyclic Wilson loop. We show how these functions get mixed under renormalization.

  4. Loop functions in thermal QCD

    Directory of Open Access Journals (Sweden)

    Vairo Antonio

    2014-01-01

    Full Text Available We discuss divergences of loop functions in thermal QCD and compute perturbatively the Polyakov loop, the Polyakov loop correlator and the cyclic Wilson loop. We show how these functions get mixed under renormalization.

  5. Origin and genetic diversity of Egyptian native chickens based on complete sequence of mitochondrial DNA D-loop region.

    Science.gov (United States)

    Osman, Sayed A-M; Yonezawa, Takahiro; Nishibori, Masahide

    2016-06-01

    Domestic chickens (Gallus gallus) play a significant role, ranging from food and entertainment to religion and ornamentation. However, the details on their domestication process are still controversial, especially the origin and evolution of African chickens. Egypt is thought to be important place for this event because of its geographic location as well as its long history of civilization. However, the genetic component and structure of Egyptian native chicken (ENC) have not been studied so far. The aim of this study is to clarify the origin and evolution of African chickens through assessing the genetic diversities and structure of five ENC breeds using the mitochondrial D-loop sequences. Our results suggest there is genetic differentiation between the pure native breeds and the improved native breeds. The latter breeds were established by the hybridization of the pure native and the exotic breeds. The pure native breeds were estimated to be established about 800 years ago. Subsequently, we extensively analyzed the D-loop sequences from the ENC as well as the globally collected chickens (2,010 individuals in total). Our phylogenetic tree among the regional populations shows African chickens can be separated to two distinct clades. The first clade consists of North African (Egypt), Central African (Sudan and Cameroon), European, and West (and Central) Asian chickens. The second clade consists of East African (Kenya, Malawi, and Zimbabwe) and Pacific chickens. It suggests the dual origins of African native chickens. The first group was probably originated from South Asia, and then migrated to West Asia, and finally arrived to Africa thorough Egypt. The second group migrated from Pacific to East Africa via Indian Ocean probably by Austronesian people. This dual origin hypothesis as well as estimated divergence times in this study is harmonious with the archaeological and historical evidences. Our migration analysis suggests there is limited gene flow within African

  6. 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

  7. A neuro-inspired model-based closed-loop neuroprosthesis for the substitution of a cerebellar learning function in anesthetized rats

    Science.gov (United States)

    Hogri, Roni; Bamford, Simeon A.; Taub, Aryeh H.; Magal, Ari; Giudice, Paolo Del; Mintz, Matti

    2015-02-01

    Neuroprostheses could potentially recover functions lost due to neural damage. Typical neuroprostheses connect an intact brain with the external environment, thus replacing damaged sensory or motor pathways. Recently, closed-loop neuroprostheses, bidirectionally interfaced with the brain, have begun to emerge, offering an opportunity to substitute malfunctioning brain structures. In this proof-of-concept study, we demonstrate a neuro-inspired model-based approach to neuroprostheses. A VLSI chip was designed to implement essential cerebellar synaptic plasticity rules, and was interfaced with cerebellar input and output nuclei in real time, thus reproducing cerebellum-dependent learning in anesthetized rats. Such a model-based approach does not require prior system identification, allowing for de novo experience-based learning in the brain-chip hybrid, with potential clinical advantages and limitations when compared to existing parametric ``black box'' models.

  8. A paradigm-based evolution of chemical engineering

    Institute of Scientific and Technical Information of China (English)

    Alexandru Woinaroschy

    2016-01-01

    A short presentation of chemical engineering evolution, as guided by its paradigms, is exposed. The first paradigm–unit operations–has emerged as a necessity of systematization due to the explosion of chemical industrial applica-tions at the end of 19th century. The birth in the late 1950s of the second paradigm–transport phenomena–was the consequence of the need for a deep, scientific knowledge of the phenomena that explain what happens inside of unit operations. In the second part of 20th century, the importance of chemical product properties and qualities has become essential y in the market fights. Accordingly, it was required with additional and even new fundamen-tal approaches, and product engineering was recognized as the third paradigm. Nowadays chemical industry, as a huge materials and energy consumer, and with a strong ecological impact, couldn't remain outside of sustainability requirements. The basics of the fourth paradigm–sustainable chemical engineering–are now formulated.

  9. PANET: a GPU-based tool for fast parallel analysis of robustness dynamics and feed-forward/feedback loop structures in large-scale biological networks.

    Directory of Open Access Journals (Sweden)

    Hung-Cuong Trinh

    Full Text Available It has been a challenge in systems biology to unravel relationships between structural properties and dynamic behaviors of biological networks. A Cytoscape plugin named NetDS was recently proposed to analyze the robustness-related dynamics and feed-forward/feedback loop structures of biological networks. Despite such a useful function, limitations on the network size that can be analyzed exist due to high computational costs. In addition, the plugin cannot verify an intrinsic property which can be induced by an observed result because it has no function to simulate the observation on a large number of random networks. To overcome these limitations, we have developed a novel software tool, PANET. First, the time-consuming parts of NetDS were redesigned to be processed in parallel using the OpenCL library. This approach utilizes the full computing power of multi-core central processing units and graphics processing units. Eventually, this made it possible to investigate a large-scale network such as a human signaling network with 1,609 nodes and 5,063 links. We also developed a new function to perform a batch-mode simulation where it generates a lot of random networks and conducts robustness calculations and feed-forward/feedback loop examinations of them. This helps us to determine if the findings in real biological networks are valid in arbitrary random networks or not. We tested our plugin in two case studies based on two large-scale signaling networks and found interesting results regarding relationships between coherently coupled feed-forward/feedback loops and robustness. In addition, we verified whether or not those findings are consistently conserved in random networks through batch-mode simulations. Taken together, our plugin is expected to effectively investigate various relationships between dynamics and structural properties in large-scale networks. Our software tool, user manual and example datasets are freely available at http://panet-csc.sourceforge.net/.

  10. 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

  11. My contribution to broadening the base of chemical engineering.

    Science.gov (United States)

    Sargent, Roger W H

    2011-01-01

    This paper is a short account, from a personal viewpoint, of the various contributions I have made to expand the academic basis of chemical engineering from its origin in the unifying concept of unit operations, focussed on process design, to encompassing all the professional activities of industrial chemical engineers. This includes all aspects of planning and scheduling the operations as well as designing and controlling the process plant. The span of my career also happens to include the birth of the age of computing, with all the consequential implications. PMID:22432607

  12. The Duel Strings versus Loops

    CERN Document Server

    Vaas, R

    2004-01-01

    Physicists in search of the foundation of the world: how tiny objects can create matter, energy and even space and time - and possibly countless other universes. -- This article is meant as an introduction into quantum geometry (loop quantum gravity) and string theory, written for the general audience. Partly, this article is also a conference report and review, based on the "Strings Meet Loops" conference at the Max-Planck-Institute for Gravitational Physics (Albert Einstein Institute), Golm/Germany, in October 2003. -- Keywords: quantum geometry, loop quantum gravity, string theory, string cosmology, spin networks, spin foams, anthropic principle, theory of everything, Abhay Ashtekar, Martin Bojowald, Michael Douglas, Jerzy Lewandowski, Hermann Nicolai, Robert Oeckl, Fernando Quevedo, Carlo Rovelli, Amitabha Sen, Lee Smolin, Leonard Susskind.

  13. Chemical Response of CESM/CAM-Chem to MOPITT CO Ensemble-based Chemical Data Assimilation

    Science.gov (United States)

    Gaubert, B.; Arellano, A. F.; Barré, J.; Worden, H. M.; Emmons, L. K.; Tilmes, S.; Buchholz, R. R.; Wiedinmyer, C.; Vitt, F.; Anderson, J. L.; Deeter, M. N.; Edwards, D. P.

    2015-12-01

    Carbon Monoxide is a key component in tropospheric chemistry. It plays an important role by affecting the oxidative capacity through its reaction with OH and being a precursor of tropospheric ozone. One year of multispectral retrievals of CO partial columns obtained from the MOPITT instrument have been assimilated into the Community Atmosphere Model with Chemistry (CAM-Chem). The assimilation is carried out using an Ensemble Adjustment Kalman Filter algorithm within the Data Assimilation Research Testbed (DART) package. Two assimilation experiments have been performed: 1) assimilation of meteorological observations and 2) joint assimilation of meteorological observations and MOPITT CO. We first evaluate the assimilation performance by investigating skill scores and other statistics for the two experiments, and comparing to independent CO datasets such as surface (WDCGG), aircraft (MOZAIC-IAGOS), and FTS (NDACC). Our results clearly demonstrate an overall improvement for spatio-temporal magnitude and variability in representing CO abundance in CAM-Chem. We then investigate the response of CAM-Chem to changes in CO fields (via CO assimilation) focusing mainly on the oxidative capacity (i.e., OH distribution, methane lifetime) and CO chemical production and loss (i.e., regional to global budget). This is carried out by analyzing the mean 6-hourly forecast adjustments as reflected between the two experiments. We show that changes in CO directly impact OH abundance, with subsequent non-linear responses in CO chemical production (CO from methane and VOCs) and CO loss. This is clearly evident in NOx-limited regions (e.g., Southern Hemisphere, remote sites). Such analysis has direct implications on the consistencies in inverse modeling estimates of CO sources through improved representation of chemical response (including full chemistry) in atmospheric chemistry models and through multi-species constraints.

  14. Electronic and chemical properties of graphene-based structures:

    DEFF Research Database (Denmark)

    Vanin, Marco

    are easier to remove and therefore only zigzag edges are left. Finally, functionalized graphene has been investigated as catalyst for the electrochemical reduction of CO2 to chemical fuels and comparisons are made with traditional transition-metal surfaces. The investigated porphyrin-like structures...... are attractive candidates although issues regarding the poisoning of the active site remain to be addressed....

  15. Holonomy loops, spectral triples and quantum gravity

    DEFF Research Database (Denmark)

    Johannes, Aastrup; Grimstrup, Jesper Møller; Nest, Ryszard

    2009-01-01

    We review the motivation, construction and physical interpretation of a semi-finite spectral triple obtained through a rearrangement of central elements of loop quantum gravity. The triple is based on a countable set of oriented graphs and the algebra consists of generalized holonomy loops...

  16. Amplifying the SERS signal of DNA bases via the chemical resonance

    Science.gov (United States)

    Freeman, Lindsay M.; Pang, Lin; Fainman, Yeshaiahu

    2015-03-01

    Label-free detection methods of DNA bases using surface-enhanced Raman spectroscopy (SERS) have yet to be successfully utilized due to inconsistent signal readouts. We have identified the primary reason for the discrepancies in the SERS signals of nucleic acids as being caused by the charge-transfer chemical resonance of the base silver system which is dependent on excitation wavelength. Time-dependent density functional theory (TD-DFT) methods to calculate the electronic transitions and resonance Raman spectra of base silver complexes are performed, and the optimal excitation wavelength for the charge-transfer electronic transition is found for each base silver complex. The enhancement caused by the chemical resonance is then experimentally measured for adenine, cytosine, guanine and thymine at multiple excitation wavelengths. The dependence of the Raman intensity on excitation wavelength shows good agreement with the TD-DFT calculations. In order to fully achieve the maximum Raman intensity, both the electromagnetic and chemical resonance must be enhanced by the appropriate wavelength selection. Based on the optimal chemical resonance Raman wavelength, we design a SERS substrate which has an electromagnetic maximum wavelength that matches the chemical resonance wavelength. By aligning both resonances, the highest Raman intensity can be found for each base silver system. We have proven that the variance in DNA bases' Raman intensities are caused by chemical enhancement. By incorporating the chemical resonance and optimizing both the chemical and electromagnetic resonance, we believe a label-free DNA SERS based detection method can be realized.

  17. Degenerate four-wave mixing based all-optical wavelength conversion in a semiconductor optical amplifier and highly-nonlinear photonic crystal fiber parametric loop mirror

    Science.gov (United States)

    Liu, Jianguo; Cheng, Tee Hiang; Yeo, Yong kee; Wang, Yixin; Xue, Lifang; Wang, Dawei; Yu, Xiaojun

    2008-11-01

    The idler is separated from the co-propagating pump in a degenerate four-wave mixing (DFWM) with a symmetrical parametric loop mirror (PALM), which is composed of two identical SOAs and a 70 m highly-nonlinear photonic crystal fiber (HN-PCF). The signal and pump are coupled into the symmetrical PALM from different ports, respectively. After the DFWM based wavelength conversion (WC) in the clockwise and anticlockwise, the idler exits from the signal port, while the pump outputs from its input port. Therefore, the pump is effectively suppressed in the idler channel without a high-speed tunable filter. Contrast to a traditional PALM, the DFWM based conversion efficiency is increased greatly, and the functions of the amplification and the WC are integrated in the smart SOA and HN-PCF PALM.

  18. 基于边光滑度的Loop自适应细分曲面算法%Adaptive Subdivision Algorithm Based on the Loop Subdivision

    Institute of Scientific and Technical Information of China (English)

    吴元翠

    2013-01-01

    The traditional Loop subdivision surface algorithm is studied at first, the analysis show that the increase of the number of triangular mesh is growing too fast in the traditional Loop subdivision algorithm. In order to solve this problem ,an adaptive sub?division surface algorithm is given. This algorithm bases on the included angle of the two normal vector of the two adjacent triangles to judge the more smooth and nonsmooth area in subdivision grid ,than subdivides the nonsmooth area only. The experimental re?sults show that this algorithm improves the speed of subdivision processing, and the model is easy to implement.%首先研究了传统的Loop细分曲面算法,通过分析发现随着细分次数的增多细分算法中三角形网格片数增长过快.针对这一问题提出一种自适应细分曲面算法.算法根据相邻两个三角形面上的法向量的夹角,判断细分网格中较为光滑和非光滑的区域.实验结果表明,算法提高了数据处理速度,并且模型简单易实现.

  19. A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular Velocity Error Modeling

    Directory of Open Access Journals (Sweden)

    Yanshun Zhang

    2015-02-01

    Full Text Available With the open-loop fiber optic gyro (OFOG model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage  and temperature  as the input variables and angular velocity error  as the output variable. Firstly, the angular velocity error  is extracted from OFOG output signals, and then the output voltage , temperature  and angular velocity error  are used as the learning samples to train a Radial-Basis-Function (RBF neural network model. Then the nonlinear mapping model over T,  and  is established and thus  can be calculated automatically to compensate OFOG errors according to  and . The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by ,  and  relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by ,  and , respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity.

  20. Testable two-loop radiative neutrino mass model based on an LLQd^cQd^c effective operator

    CERN Document Server

    Angel, Paul W; Rodd, Nicholas L; Schmidt, Michael A; Volkas, Raymond R

    2013-01-01

    A new two-loop radiative Majorana neutrino mass model is constructed from the gauge- invariant effective operator L^i L^j Q^k d^c Q^l d^c \\epsilon_{ik} \\epsilon_{jl} that violates lepton number conservation by two units. The ultraviolet completion features two scalar leptoquark flavors and a color-octet Majorana fermion. We show that there exists a region of parameter space where the neutrino oscillation data can be fitted while simultaneously meeting flavor-violation and collider bounds. The model is testable through lepton flavor-violating processes such as {\\mu} -> e{\\gamma}, {\\mu} -> eee, and {\\mu}N -> eN conversion, as well as collider searches for the scalar leptoquarks and color-octet fermion. We computed and compiled a list of necessary Passarino-Veltman integrals up to boxes in the approximation of vanishing external momenta and made them available as a Mathematica package, denoted as ANT.

  1. Efficient and Specific Detection of Salmonella in Food Samples Using a stn-Based Loop-Mediated Isothermal Amplification Method

    Directory of Open Access Journals (Sweden)

    Mevaree Srisawat

    2015-01-01

    Full Text Available The Salmonella enterotoxin (stn gene exhibits high homology among S. enterica serovars and S. bongori. A set of 6 specific primers targeting the stn gene were designed for detection of Salmonella spp. using the loop-mediated isothermal amplification (LAMP method. The primers amplified target sequences in all 102 strains of 87 serovars of Salmonella tested and no products were detected in 57 non-Salmonella strains. The detection limit in pure cultures was 5 fg DNA/reaction when amplified at 65°C for 25 min. The LAMP assay could detect Salmonella in artificially contaminated food samples as low as 220 cells/g of food without a preenrichment step. However, the sensitivity was increased 100-fold (~2 cells/g following 5 hr preenrichment at 35°C. The LAMP technique, with a preenrichment step for 5 and 16 hr, was shown to give 100% specificity with food samples compared to the reference culture method in which 67 out of 90 food samples gave positive results. Different food matrixes did not interfere with LAMP detection which employed a simple boiling method for DNA template preparation. The results indicate that the LAMP method, targeting the stn gene, has great potential for detection of Salmonella in food samples with both high specificity and high sensitivity.

  2. Loops and trees

    Science.gov (United States)

    Caron-Huot, S.

    2011-05-01

    We investigate relations between loop and tree amplitudes in quantum field theory that involve putting on-shell some loop propagators. This generalizes the so-called Feynman tree theorem which is satisfied at 1-loop. Exploiting retarded boundary conditions, we give a generalization to ℓ-loop expressing the loops as integrals over the on-shell phase space of exactly ℓ particles. We argue that the corresponding integrand for ℓ > 2 does not involve the forward limit of any physical tree amplitude, except in planar gauge theories. In that case we explicitly construct the relevant physical amplitude. Beyond the planar limit, abandoning direct integral representations, we propose that loops continue to be determined implicitly by the forward limit of physical connected trees, and we formulate a precise conjecture along this line. Finally, we set up technology to compute forward amplitudes in supersymmetric theories, in which specific simplifications occur.

  3. Aperture-Tolerant, Chemical-Based Methods to Reduce Channeling

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Seright

    2007-09-30

    This final technical progress report describes work performed from October 1, 2004, through May 16, 2007, for the project, 'Aperture-Tolerant, Chemical-Based Methods to Reduce Channeling'. We explored the potential of pore-filling gels for reducing excess water production from both fractured and unfractured production wells. Several gel formulations were identified that met the requirements--i.e., providing water residual resistance factors greater than 2,000 and ultimate oil residual resistance factors (F{sub rro}) of 2 or less. Significant oil throughput was required to achieve low F{sub rro} values, suggesting that gelant penetration into porous rock must be small (a few feet or less) for existing pore-filling gels to provide effective disproportionate permeability reduction. Compared with adsorbed polymers and weak gels, strong pore-filling gels can provide greater reliability and behavior that is insensitive to the initial rock permeability. Guidance is provided on where relative-permeability-modification/disproportionate-permeability-reduction treatments can be successfully applied for use in either oil or gas production wells. When properly designed and executed, these treatments can be successfully applied to a limited range of oilfield excessive-water-production problems. We examined whether gel rheology can explain behavior during extrusion through fractures. The rheology behavior of the gels tested showed a strong parallel to the results obtained from previous gel extrusion experiments. However, for a given aperture (fracture width or plate-plate separation), the pressure gradients measured during the gel extrusion experiments were much higher than anticipated from rheology measurements. Extensive experiments established that wall slip and first normal stress difference were not responsible for the pressure gradient discrepancy. To explain the discrepancy, we noted that the aperture for gel flow (for mobile gel wormholing through concentrated

  4. Calculations of NMR chemical shifts with APW-based methods

    Science.gov (United States)

    Laskowski, Robert; Blaha, Peter

    2012-01-01

    We present a full potential, all electron augmented plane wave (APW) implementation of first-principles calculations of NMR chemical shifts. In order to obtain the induced current we follow a perturbation approach [Pickard and Mauri, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.63.245101 63, 245101 (2001)] and extended the common APW + local orbital (LO) basis by several LOs at higher energies. The calculated all-electron current is represented in traditional APW manner as Fourier series in the interstitial region and with a spherical harmonics representation inside the nonoverlapping atomic spheres. The current is integrated using a “pseudocharge” technique. The implementation is validated by comparison of the computed chemical shifts with some “exact” results for spherical atoms and for a set of solids and molecules with available published data.

  5. Design of LTCC-based Ceramic Structure for Chemical Microreactor

    OpenAIRE

    D. Belavic; Hrovat, M.; G. Dolanc; Santo Zarnik, M.; Holc, J.; Makarovic, K.

    2012-01-01

    The design of ceramic chemical microreactor for the production of hydrogen needed in portable polymer-electrolyte membrane (PEM) fuel cells is presented. The microreactor was developed for the steam reforming of liquid fuels with water into hydrogen. The complex three-dimensional ceramic structure of the microreactor includes evaporator(s), mixer(s), reformer and combustor. Low-temperature co-fired ceramic (LTCC) technology was used to fabricate the ceramic structures with buried cavities and...

  6. Diffusion of Wilson Loops

    OpenAIRE

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

    2004-01-01

    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 i...

  7. Erythromycin binding is reduced in ribosomes with conformational alterations in the 23 S rRNA peptidyl transferase loop

    DEFF Research Database (Denmark)

    Douthwaite, S; Aagaard, C

    1993-01-01

    that are induced by mutations in the peptidyl transferase loop, and to determine how these changes affect drug interaction. Mutations at positions 2057 (G-->A) and 2058 (A-->G, or -->U), all of which confer drug resistance, induce a more open conformation in the peptidyl transferase loop. Erythromycin still......The antibiotic erythromycin inhibits protein synthesis by binding to the 50 S ribosomal subunit, where the drug interacts with the unpaired bases 2058A and 2059A in the peptidyl transferase loop of 23 S rRNA. We used a chemical modification approach to analyse conformational changes...... previously been shown to alter drug tolerances, gave no detectable effects on the structure of the peptidyl transferase loop or on erythromycin binding. Dual mutations at positions 2032 and 2058, however, induce a marked change in the rRNA conformation with opening of the phylogenetically conserved base...

  8. Examination of Perovskite Structure CaMnO3-δ with MgO Addition as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Using Methane and Syngas

    Directory of Open Access Journals (Sweden)

    Dazheng Jing

    2013-01-01

    Full Text Available Perovskite structure oxygen carriers with the general formula CaMnxMg1-xO3-δ were spray-dried and examined in a batch fluidized bed reactor. The CLOU behavior, reactivity towards methane, and syngas were investigated at temperature 900°C to 1050°C. All particles showed CLOU behavior at these temperatures. For experiments with methane, a bed mass corresponding to 57 kg/MW was used in the reactor, and the average CH4 to CO2 conversion was above 97% for most materials. Full syngas conversion was achieved for all materials utilizing a bed mass corresponding to 178 kg/MW. SEM/EDX and XRD confirmed the presence of MgO in the fresh and used samples, indicating that the Mg cation is not incorporated into the perovskite structure and the active compound is likely pure CaMnO3-δ. The very high reactivity with fuel gases, comparable to that of baseline oxygen carriers of NiO, makes these perovskite particles highly interesting for commercial CLC application. Contrary to NiO, oxygen carriers based on CaMnO3-δ have no thermodynamic limitations for methane oxidation to CO2 and H2O, not to mention that the materials are environmentally friendly and can utilize much cheaper raw materials for production. The physical properties, crystalline phases, and morphology information were also determined in this work.

  9. Genetic Diversity and Phylogenetic Evolution of Tibetan Sheep Based on mtDNA D-Loop Sequences

    Science.gov (United States)

    Yue, Yaojing; Guo, Xian; Guo, Tingting; Chu, Min; Wang, Fan; Han, Jilong; Feng, Ruilin; Sun, Xiaoping; Niu, Chune; Yang, Bohui; Guo, Jian; Yuan, Chao

    2016-01-01

    The molecular and population genetic evidence of the phylogenetic status of the Tibetan sheep (Ovis aries) is not well understood, and little is known about this species’ genetic diversity. This knowledge gap is partly due to the difficulty of sample collection. This is the first work to address this question. Here, the genetic diversity and phylogenetic relationship of 636 individual Tibetan sheep from fifteen populations were assessed using 642 complete sequences of the mitochondrial DNA D-loop. Samples were collected from the Qinghai-Tibetan Plateau area in China, and reference data were obtained from the six reference breed sequences available in GenBank. The length of the sequences varied considerably, between 1031 and 1259 bp. The haplotype diversity and nucleotide diversity were 0.992±0.010 and 0.019±0.001, respectively. The average number of nucleotide differences was 19.635. The mean nucleotide composition of the 350 haplotypes was 32.961% A, 29.708% T, 22.892% C, 14.439% G, 62.669% A+T, and 37.331% G+C. Phylogenetic analysis showed that all four previously defined haplogroups (A, B, C, and D) were found in the 636 individuals of the fifteen Tibetan sheep populations but that only the D haplogroup was found in Linzhou sheep. Further, the clustering analysis divided the fifteen Tibetan sheep populations into at least two clusters. The estimation of the demographic parameters from the mismatch analyses showed that haplogroups A, B, and C had at least one demographic expansion in Tibetan sheep. These results contribute to the knowledge of Tibetan sheep populations and will help inform future conservation programs about the Tibetan sheep native to the Qinghai-Tibetan Plateau. PMID:27463976

  10. Genetic Diversity and Phylogenetic Evolution of Tibetan Sheep Based on mtDNA D-Loop Sequences.

    Directory of Open Access Journals (Sweden)

    Jianbin Liu

    Full Text Available The molecular and population genetic evidence of the phylogenetic status of the Tibetan sheep (Ovis aries is not well understood, and little is known about this species' genetic diversity. This knowledge gap is partly due to the difficulty of sample collection. This is the first work to address this question. Here, the genetic diversity and phylogenetic relationship of 636 individual Tibetan sheep from fifteen populations were assessed using 642 complete sequences of the mitochondrial DNA D-loop. Samples were collected from the Qinghai-Tibetan Plateau area in China, and reference data were obtained from the six reference breed sequences available in GenBank. The length of the sequences varied considerably, between 1031 and 1259 bp. The haplotype diversity and nucleotide diversity were 0.992±0.010 and 0.019±0.001, respectively. The average number of nucleotide differences was 19.635. The mean nucleotide composition of the 350 haplotypes was 32.961% A, 29.708% T, 22.892% C, 14.439% G, 62.669% A+T, and 37.331% G+C. Phylogenetic analysis showed that all four previously defined haplogroups (A, B, C, and D were found in the 636 individuals of the fifteen Tibetan sheep populations but that only the D haplogroup was found in Linzhou sheep. Further, the clustering analysis divided the fifteen Tibetan sheep populations into at least two clusters. The estimation of the demographic parameters from the mismatch analyses showed that haplogroups A, B, and C had at least one demographic expansion in Tibetan sheep. These results contribute to the knowledge of Tibetan sheep populations and will help inform future conservation programs about the Tibetan sheep native to the Qinghai-Tibetan Plateau.

  11. Genetic Diversity and Phylogenetic Evolution of Tibetan Sheep Based on mtDNA D-Loop Sequences.

    Science.gov (United States)

    Liu, Jianbin; Ding, Xuezhi; Zeng, Yufeng; Yue, Yaojing; Guo, Xian; Guo, Tingting; Chu, Min; Wang, Fan; Han, Jilong; Feng, Ruilin; Sun, Xiaoping; Niu, Chune; Yang, Bohui; Guo, Jian; Yuan, Chao

    2016-01-01

    The molecular and population genetic evidence of the phylogenetic status of the Tibetan sheep (Ovis aries) is not well understood, and little is known about this species' genetic diversity. This knowledge gap is partly due to the difficulty of sample collection. This is the first work to address this question. Here, the genetic diversity and phylogenetic relationship of 636 individual Tibetan sheep from fifteen populations were assessed using 642 complete sequences of the mitochondrial DNA D-loop. Samples were collected from the Qinghai-Tibetan Plateau area in China, and reference data were obtained from the six reference breed sequences available in GenBank. The length of the sequences varied considerably, between 1031 and 1259 bp. The haplotype diversity and nucleotide diversity were 0.992±0.010 and 0.019±0.001, respectively. The average number of nucleotide differences was 19.635. The mean nucleotide composition of the 350 haplotypes was 32.961% A, 29.708% T, 22.892% C, 14.439% G, 62.669% A+T, and 37.331% G+C. Phylogenetic analysis showed that all four previously defined haplogroups (A, B, C, and D) were found in the 636 individuals of the fifteen Tibetan sheep populations but that only the D haplogroup was found in Linzhou sheep. Further, the clustering analysis divided the fifteen Tibetan sheep populations into at least two clusters. The estimation of the demographic parameters from the mismatch analyses showed that haplogroups A, B, and C had at least one demographic expansion in Tibetan sheep. These results contribute to the knowledge of Tibetan sheep populations and will help inform future conservation programs about the Tibetan sheep native to the Qinghai-Tibetan Plateau. PMID:27463976

  12. A new open-loop fiber optic gyro error compensation method based on angular velocity error modeling.

    Science.gov (United States)

    Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing

    2015-01-01

    With the open-loop fiber optic gyro (OFOG) model, output voltage and angular velocity can effectively compensate OFOG errors. However, the model cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular velocities. This paper puts forward a modeling scheme with OFOG output voltage u and temperature T as the input variables and angular velocity error Δω as the output variable. Firstly, the angular velocity error Δω is extracted from OFOG output signals, and then the output voltage u, temperature T and angular velocity error Δω are used as the learning samples to train a Radial-Basis-Function (RBF) neural network model. Then the nonlinear mapping model over T, u and Δω is established and thus Δω can be calculated automatically to compensate OFOG errors according to T and u. The results of the experiments show that the established model can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular velocity are decreased by 97.0%, 97.1% and 96.5% relative to their initial values, respectively. Compared with the direct modeling of gyro angular velocity, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by 1.6%, 1.4% and 1.42%, respectively, so the performance of this method is better than that of the direct modeling for gyro angular velocity. PMID:25734642

  13. DEVELOPMENT ASSESSMENT OF ALTERNATIVE PRACTICUM II BASIC CHEMICAL THROUGH CHEMISTRY FAIR PROJECT ( CFP BASED CONSERVATION USING CHEMICAL DAILY

    Directory of Open Access Journals (Sweden)

    I. Urwatin Wusqo

    2015-11-01

    Full Text Available This study aims to (1 develop an alternative assessment on the 2nd General Chemistry Experiment through conservation-based chemistry fair project by utilizing the daily chemical (2 Determine the level of validity, practicality and effectiveness. This research is the development (Research Development development model applied Dick and Carey (1985. The subject of limited testing and field trials is subject lecturers and students of Science Education UNNES. Determined by purposive sample, the lecturers and the students who take the course 2nd General Chemistry Experiment. The data obtained from this trial are: (1 input from experts, to determine the content and construct validity of the assessment feature; (2 input from a limited sample testing, to determine the practicality of chemistry clue fair project (CFP based conservation by utilizing chemical daily; Instrument data collectors in the form of a questionnaire legibility chemistry making instructions fair project (CFP based conservation by utilizing daily chemical, scoring guidelines. (3 student learning outcomes data to determine the effectiveness of the assessment. Input from experts student questionnaire, and the value of chemistry fair project (CFP limited test samples analyzed qualitatively and quantitatively. Assessment of 2nd General Chemistry Experiment alternative developed is successful well-developed assessment if valid, practical, and effective.

  14. Neutron transport in irradiation loops (IRENE loop)

    International Nuclear Information System (INIS)

    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

  15. Loop Quantum Cosmology from Loop Quantum Gravity

    OpenAIRE

    Alesci, Emanuele; Cianfrani, Francesco

    2014-01-01

    We show how Loop Quantum Cosmology can be derived as an effective semiclassical description of Loop Quantum Gravity. Using the tools of QRLG, a gauge fixed version of LQG, we take the coherent states of the fundamental microscopic theory suitable to describe a Bianchi I Universe and we find a mapping between the expectation value of the Hamiltonian and the dynamics of LQC. Our results are in agreement with a lattice refinement framework for LQC, thus the so called ``old'' and ``improved-dynam...

  16. Raman-spectroscopy-based chemical contaminant detection in milk powder

    Science.gov (United States)

    Dhakal, Sagar; Chao, Kuanglin; Qin, Jianwei; Kim, Moon S.

    2015-05-01

    Addition of edible and inedible chemical contaminants in food powders for purposes of economic benefit has become a recurring trend. In recent years, severe health issues have been reported due to consumption of food powders contaminated with chemical substances. This study examines the effect of spatial resolution used during spectral collection to select the optimal spatial resolution for detecting melamine in milk powder. Sample depth of 2mm, laser intensity of 200mw, and exposure time of 0.1s were previously determined as optimal experimental parameters for Raman imaging. Spatial resolution of 0.25mm was determined as the optimal resolution for acquiring spectral signal of melamine particles from a milk-melamine mixture sample. Using the optimal resolution of 0.25mm, sample depth of 2mm and laser intensity of 200mw obtained from previous study, spectral signal from 5 different concentration of milk-melamine mixture (1%, 0.5%, 0.1%, 0.05%, and 0.025%) were acquired to study the relationship between number of detected melamine pixels and corresponding sample concentration. The result shows that melamine concentration has a linear relation with detected number of melamine pixels with correlation coefficient of 0.99. It can be concluded that the quantitative analysis of powder mixture is dependent on many factors including physical characteristics of mixture, experimental parameters, and sample depth. The results obtained in this study are promising. We plan to apply the result obtained from this study to develop quantitative detection model for rapid screening of melamine in milk powder. This methodology can also be used for detection of other chemical contaminants in milk powders.

  17. CuO/Al2O3作为载氧剂的流化床化学链燃烧数值模拟%Numerical Simulation of Fluidized Bed Chemical Looping Combustion Using CuO/Al2O3 as Oxygen Carrier

    Institute of Scientific and Technical Information of China (English)

    李俊; 郭雪岩

    2012-01-01

    Based on the Eulerian-Eulerian bi-fluid model and the kinetic model of the gas-solid heterogeneous chemical reactions,by adding the UDF (user defined function) code into Fluent 6.3 flow solver to integrate the chemical reaction mechanism and heat source term, the gas-solid flow processes and chemical reactions of the chemical looping combustion in the fuel reactor-the spouted fluidized bed were modeled. The influences of methane gas inlet velocities on gas-solid flow feature,heat transfer and chemical reaction rates were analyzed. With an increasing methane inlet velocity, the gas and solids are found to be mixed more intensely and the uneven distribution of gas-solid, lower quality of fluidization,and non-uniform chemical reaction rates and temperature will take place due to the formation,collision and burst of the bubbles. It is also found that there are some spots of higher temperature in local regions, which may lead to particles agglomeration and lower efficiencies of methane combustion.%以欧拉-欧拉双流体模型和气固非均相化学反应动力学为基础,嵌入了气固化学反应速率方程和反应内热源项的UDF(自定义函数)程序,对化学链燃烧燃料反应器——鼓泡流化床内气固两相流动及化学反应过程进行了数值模拟,并分析了甲烷进气速度对床内气固两相流动、传热及化学反应速率的影响.结果表明:随着甲烷进气速度增加,床内气固混合更加剧烈,气泡的产生、碰撞和破碎使得气固分布不均,流化质量下降,导致反应器内化学反应速率以及温度分布不均,床内局部存在的高温区域将使颗粒温度过高而烧结,降低了甲烷燃烧效率.

  18. Modified Projective Synchronization between Different Fractional-Order Systems Based on Open-Plus-Closed-Loop Control and Its Application in Image Encryption

    Directory of Open Access Journals (Sweden)

    Hongjuan Liu

    2014-01-01

    Full Text Available A new general and systematic coupling scheme is developed to achieve the modified projective synchronization (MPS of different fractional-order systems under parameter mismatch via the Open-Plus-Closed-Loop (OPCL control. Based on the stability theorem of linear fractional-order systems, some sufficient conditions for MPS are proposed. Two groups of numerical simulations on the incommensurate fraction-order system and commensurate fraction-order system are presented to justify the theoretical analysis. Due to the unpredictability of the scale factors and the use of fractional-order systems, the chaotic data from the MPS is selected to encrypt a plain image to obtain higher security. Simulation results show that our method is efficient with a large key space, high sensitivity to encryption keys, resistance to attack of differential attacks, and statistical analysis.

  19. Controller development of photo bioreactor for closed-loop regulation of O2 production based on ANN model reference control and computer simulation

    Science.gov (United States)

    Hu, Dawei; Zhang, Houkai; Zhou, Rui; Li, Ming; Sun, Yi

    2013-02-01

    When Bioregenerative Life Support System (BLSS) is used for long-term deep space exploration in the future, it is possible to perform closed-loop control on growth of microalgae to effectively regulate O2 production process in emergencies. However, designing controller of microalgae cultivating device (MCD) by means of traditional methods is very difficult or even impossible due to its highly nonlinearity and large operation scope. In our research, the Artificial Neural Network Model Reference Control (ANN-MRC) method was therefore utilized for model identification and controller design for O2 production process of a specific MCD prototype—photo bioreactor (PBR), based on actual experiment and computer simulation. The results demonstrated that the ANN-MRC servo controller could robustly and self-adaptively control and regulate the light intensity of PBR to make O2 concentrations in vent pipe be in line with step reference concentrations with prescribed dynamic response performance.

  20. A multiwavelength Er-doped fiber laser using a nonlinear optical loop mirror and a twin-core fiber-based Mach–Zehnder interferometer

    International Nuclear Information System (INIS)

    A multiwavelength Er-doped fiber (EDF) laser was proposed and experimentally demonstrated using a nonlinear optical loop mirror (NOLM) and a twin-core fiber-based Mach–Zehnder interferometer (TCF MZI). A total of 40 lasing wavelengths around the wavelength of 1560 nm with an average signal-to-noise ratio (SNR) of 28 dB and 30 lasing wavelengths around the wavelength of 1530 nm with an average SNR of 20 dB were achieved when the EDF length was 6 and 2 m, respectively. To the best of our knowledge, this is the first time that multiwavelength oscillations have been obtained in the wavelength range of 1530 nm by using a NOLM. The wavelength spacing is ∼0.19 nm which is determined by the TCF MZI. In addition, the effects of the pump power and the state of polarization on the performance of the multiwavelength EDF laser were investigated. (letter)

  1. Optical single sideband modulation based on a high-order birefringent filter using cascaded Solc-Sagnac and Lyot-Sagnac loops.

    Science.gov (United States)

    Feng, Danqi; Sun, Junqiang

    2016-08-01

    We propose and experimentally demonstrate a simple and flexible photonic approach to implementing single sideband (SSB) modulation based on optical spectral filtering. The high-order birefringent filter is realized through the cascaded Solc-Sagnac and Lyot-Sagnac loops. By adjusting the rotation angle of the polarization controller (PC), the notch position to remove undesired sidebands changes. The frequency for SSB modulation varies accordingly. The periodical response of the filter spectrum allows both the carrier wavelength and the optical carrier to sideband ratio (OCSR) to be tunable. SSB modulation over a frequency range from 5 to 40 GHz and tunable OCSR ranging from -9.174 to 34.408 dB are obtained. The significant merits of the proposed approach are the simple structure, easy operation, large frequency range, tunable OCSR, and wavelength independence. The approach has potential applications in optimizing the transmission performance of photonic microwave signal processing systems. PMID:27472643

  2. AC bias characterization of low noise bolometers for SAFARI using an Open-Loop Frequency Domain SQUID-based multiplexer operating between 1 and 5 MHz

    CERN Document Server

    Gottardi, Luciano; Gao, Jan-R; Hartog, Roland den; Hijmering, Richard; Hoevers, Henk; Khosropanah, Pourya; de Korte, Piet; van der Kuur, Jan; Lindeman, Mark; Ridder, Marcel

    2016-01-01

    SRON is developing the Frequency Domain Multiplexing (FDM) readout and the ultra low NEP TES bolometers array for the infrared spectrometer SAFARI on board of the Japanese space mission SPICA. The FDM prototype of the instrument requires critical and complex optimizations. For single pixel characterization under AC bias we are developing a simple FDM system working in the frequency range from 1 to 5 MHz, based on the open loop read-out of a linearized two-stage SQUID amplifier and high Q lithographic LC resonators. We describe the details of the experimental set-up required to achieve low power loading (< 1 fW) and low noise (NEP $\\sim 10^{-19} W/Hz^{1/2}$) in the TES bolometers. We conclude the paper by comparing the performance of a $4 \\cdot 10^{-19} W/Hz^{1/2}$ TES bolometer measured under DC and AC bias.

  3. Frequency comb-based microwave transfer over fiber with $7 \\times 10^{-19}$ instability using fiber-loop optical-microwave phase detectors

    CERN Document Server

    Jung, Kwangyun; Kang, Jinho; Hunziker, Stephan; Min, Chang-Ki; Kim, Jungwon

    2013-01-01

    We demonstrate a remote microwave/radio-frequency (RF) transfer technique based on the stabilization of a fiber link using a fiber-loop optical-microwave phase detector (FLOM-PD). This method compensates for the excess phase fluctuations introduced in fiber transfer by direct phase comparison between the optical pulse train reflected from the remote site and the local microwave/RF signal using the FLOM-PD. This enables sub-fs resolution and long-term stable link stabilization while having wide timing detection range and less demand in fiber dispersion compensation. The demonstrated relative frequency instability between 2.856-GHz RF oscillators separated by a 2.3-km fiber link is $7.6 \\times 10^{-18}$ and $6.5 \\times 10^{-19}$ at 1000 s and 82500 s averaging time, respectively.

  4. Uranyl Nitrate Flow Loop

    Energy Technology Data Exchange (ETDEWEB)

    Ladd-Lively, Jennifer L [ORNL

    2008-10-01

    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{sub 2}), uranium tetrafluoride (UF{sub 4}), and uranium hexafluoride (UF{sub 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{sub 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

  5. Mammalian models of chemically induced primary malignancies exploitable for imaging-based preclinical theragnostic research

    OpenAIRE

    Liu, Yewei; YIN Ting; Feng, Yuanbo; Cona, Marlein Miranda; Huang, Gang; Liu, Jianjun; Song, Shaoli; Jiang, Yansheng; Xia, Qian; Swinnen, Johannes V; Bormans, Guy; Himmelreich, Uwe; Oyen, Raymond; Ni, Yicheng

    2015-01-01

    Compared with transplanted tumor models or genetically engineered cancer models, chemically induced primary malignancies in experimental animals can mimic the clinical cancer progress from the early stage on. Cancer caused by chemical carcinogens generally develops through three phases namely initiation, promotion and progression. Based on different mechanisms, chemical carcinogens can be divided into genotoxic and non-genotoxic ones, or complete and incomplete ones, usually with an organ-spe...

  6. Inferential protein structure determination and refinement using fast, electronic structure based backbone amide chemical shift predictions

    CERN Document Server

    Christensen, Anders S

    2015-01-01

    This report covers the development of a new, fast method for calculating the backbone amide proton chemical shifts in proteins. Through quantum chemical calculations, structure-based forudsiglese the chemical shift for amidprotonen in protein has been parameterized. The parameters are then implemented in a computer program called Padawan. The program has since been implemented in protein folding program Phaistos, wherein the method andvendes to de novo folding of the protein structures and to refine the existing protein structures.

  7. Carbon Nanostructure-Based Field-Effect Transistors for Label-Free Chemical/Biological Sensors

    OpenAIRE

    PingAn Hu; Jia Zhang; Le Li; Zhenlong Wang; William O’Neill; Pedro Estrela

    2010-01-01

    Over the past decade, electrical detection of chemical and biological species using novel nanostructure-based devices has attracted significant attention for chemical, genomics, biomedical diagnostics, and drug discovery applications. The use of nanostructured devices in chemical/biological sensors in place of conventional sensing technologies has advantages of high sensitivity, low decreased energy consumption and potentially highly miniaturized integration. Owing to their particular structu...

  8. The Loop Algorithm

    Science.gov (United States)

    Evertz, Hans Gerd

    1998-03-01

    Exciting new investigations have recently become possible for strongly correlated systems of spins, bosons, and fermions, through Quantum Monte Carlo simulations with the Loop Algorithm (H.G. Evertz, G. Lana, and M. Marcu, Phys. Rev. Lett. 70, 875 (1993).) (For a recent review see: H.G. Evertz, xxx.lanl.gov/abs/cond-mat/9707221>cond- mat/9707221.) and its generalizations. A review of this new method, its generalizations and its applications is given, including some new results. The Loop Algorithm is based on a formulation of physical models in an extended ensemble of worldlines and graphs, and is related to Swendsen-Wang cluster algorithms. It performs nonlocal changes of worldline configurations, determined by local stochastic decisions. It overcomes many of the difficulties of traditional worldline simulations. Computer time requirements are reduced by orders of magnitude, through a corresponding reduction in autocorrelations. The grand-canonical ensemble (e.g. varying winding numbers) is naturally simulated. The continuous time limit can be taken directly. Improved Estimators exist which further reduce the errors of measured quantities. The algorithm applies unchanged in any dimension and for varying bond-strengths. It becomes less efficient in the presence of strong site disorder or strong magnetic fields. It applies directly to locally XYZ-like spin, fermion, and hard-core boson models. It has been extended to the Hubbard and the tJ model and generalized to higher spin representations. There have already been several large scale applications, especially for Heisenberg-like models, including a high statistics continuous time calculation of quantum critical exponents on a regularly depleted two-dimensional lattice of up to 20000 spatial sites at temperatures down to T=0.01 J.

  9. Water loop for training

    International Nuclear Information System (INIS)

    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.)

  10. Designing of the chemical composition of steels basing on the hardenability of constructional steels

    International Nuclear Information System (INIS)

    The paper presents the original method of modelling of the relationships between chemical composition of alloy constructional steel and its hardenability, employing neural networks. Basing on the experimental results of the hardenability investigations, which employed Jominy method, the model of the neural networks was developed and fully verified experimentally. The model makes it possible to obtain Jominy hardenability curves basing on the steel chemical composition. The model of neural networks, making it possible to design the steel chemical composition, basing on the known Jominy hardenability curve shape, was developed also and fully verified numerically. (author)

  11. The role of the Polyakov loop in finite density QCD

    OpenAIRE

    de Forcrand, Ph.; Laliena, V.

    1999-01-01

    We study the behavior of the fermion determinant at finite temperature and chemical potential, as a function of the Polyakov loop. The phase of the determinant is correlated with the imaginary part of the Polyakov loop. This correlation and its consequences are considered in static QCD, in a toy model of free quarks in a constant $A_0$ background, and in simulations constraining the imaginary part of the Polyakov loop to zero.

  12. Design of LTCC-based Ceramic Structure for Chemical Microreactor

    Directory of Open Access Journals (Sweden)

    D. Belavic

    2012-04-01

    Full Text Available The design of ceramic chemical microreactor for the production of hydrogen needed in portable polymer-electrolyte membrane (PEM fuel cells is presented. The microreactor was developed for the steam reforming of liquid fuels with water into hydrogen. The complex three-dimensional ceramic structure of the microreactor includes evaporator(s, mixer(s, reformer and combustor. Low-temperature co-fired ceramic (LTCC technology was used to fabricate the ceramic structures with buried cavities and channels, and thick-film technology was used to make electrical heaters, temperature sensors and pressure sensors. The final 3D ceramic structure consists of 45 LTCC tapes. The dimensions of the structure are 75 × 41 × 9 mm3 and the weight is about 73 g.

  13. Chemical Sensors Based on Molecularly Imprinted Sol-Gel Materials

    Directory of Open Access Journals (Sweden)

    Franz L. Dickert

    2010-03-01

    Full Text Available The sol-gel technique is earning the worldwide attention of researchers in the field of material science, due to its versatility in synthesizing inorganic ceramic materials at mild conditions. High purity, homogeneity, controlled porosity, stable temperature and nanoscale structuring are the most remarkable features offered by this method for generating highly sensitive and selective matrices to incorporate analyte molecules. The crafting of sol-gel sensors through molecular imprinting has put great influence on the development of innovative chemical sensors, which can be seen from the growing number of publications in this field. The review provides a brief overview of sol-gel sensor applications, and discusses the contribution of molecular imprinting in exploring the new world of sensors.

  14. SDG-based Model Validation in Chemical Process Simulation

    Institute of Scientific and Technical Information of China (English)

    张贝克; 许欣; 马昕; 吴重光

    2013-01-01

    Signed direct graph (SDG) theory provides algorithms and methods that can be applied directly to chemical process modeling and analysis to validate simulation models, and is a basis for the development of a soft-ware environment that can automate the validation activity. This paper is concentrated on the pretreatment of the model validation. We use the validation scenarios and standard sequences generated by well-established SDG model to validate the trends fitted from the simulation model. The results are helpful to find potential problems, as-sess possible bugs in the simulation model and solve the problem effectively. A case study on a simulation model of boiler is presented to demonstrate the effectiveness of this method.

  15. Stem-loop DNA-assisted silicon nanowires-based biochemical sensors with ultra-high sensitivity, specificity, and multiplexing capability

    Science.gov (United States)

    Xie, Juan; Jiang, Xiangxu; Zhong, Yiling; Lu, Yimei; Wang, Siyi; Wei, Xinpan; Su, Yuanyuan; He, Yao

    2014-07-01

    A class of stem-loop DNA-assisted silicon nanowires (SiNWs)-based fluorescent biosensor is presented in this report. Significantly, the sensor enables rapid and sensitive detection of DNA targets with a concentration as low as 1 pM. Moreover, the large planar surface of SiNWs facilitates simultaneous assembly with different DNA strands, which is favorable for multiplexed DNA detection. On the other hand, the SiNWs-based sensor is highly efficacious for detecting heavy metal ions. Mercury ions (Hg2+) of low concentrations (e.g., 5 pM) are readily identified from its mixture with over 10 kinds of interfering metal ions, even in real water samples. Given that SiNWs can be fabricated in a facile, reproducible and low-cost manner, this kind of SiNWs-based high-performance sensor is expected to be a practical analytical tool for a variety of biological and environment-protection applications.A class of stem-loop DNA-assisted silicon nanowires (SiNWs)-based fluorescent biosensor is presented in this report. Significantly, the sensor enables rapid and sensitive detection of DNA targets with a concentration as low as 1 pM. Moreover, the large planar surface of SiNWs facilitates simultaneous assembly with different DNA strands, which is favorable for multiplexed DNA detection. On the other hand, the SiNWs-based sensor is highly efficacious for detecting heavy metal ions. Mercury ions (Hg2+) of low concentrations (e.g., 5 pM) are readily identified from its mixture with over 10 kinds of interfering metal ions, even in real water samples. Given that SiNWs can be fabricated in a facile, reproducible and low-cost manner, this kind of SiNWs-based high-performance sensor is expected to be a practical analytical tool for a variety of biological and environment-protection applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01097c

  16. Effectiveness of Instruction Based on the Constructivist Approach on Understanding Chemical Equilibrium Concepts

    Science.gov (United States)

    Akkus, Huseyin; Kadayifci, Hakki; Atasoy, Basri; Geban, Omer

    2003-01-01

    The purpose of this study was to identify misconceptions concerning chemical equilibrium concepts and to investigate the effectiveness of instruction based on the constructivist approach over traditional instruction on 10th grade students' understanding of chemical equilibrium concepts. The subjects of this study consisted of 71 10th grade…

  17. Introduction to Chemical Engineering Reactor Analysis: A Web-Based Reactor Design Game

    Science.gov (United States)

    Orbey, Nese; Clay, Molly; Russell, T.W. Fraser

    2014-01-01

    An approach to explain chemical engineering through a Web-based interactive game design was developed and used with college freshman and junior/senior high school students. The goal of this approach was to demonstrate how to model a lab-scale experiment, and use the results to design and operate a chemical reactor. The game incorporates both…

  18. Damped transverse oscillations of interacting coronal loops

    CERN Document Server

    Soler, Roberto

    2015-01-01

    Damped transverse oscillations of magnetic loops are routinely observed in the solar corona. This phenomenon is interpreted as standing kink magnetohydrodynamic waves, which are damped by resonant absorption owing to plasma inhomogeneity across the magnetic field. The periods and damping times of these oscillations can be used to probe the physical conditions of the coronal medium. Some observations suggest that interaction between neighboring oscillating loops in an active region may be important and can modify the properties of the oscillations compared to those of an isolated loop. Here we theoretically investigate resonantly damped transverse oscillations of interacting non-uniform coronal loops. We provide a semi-analytic method, based on the T-matrix theory of scattering, to compute the frequencies and damping rates of collective oscillations of an arbitrary configuration of parallel cylindrical loops. The effect of resonant damping is included in the T-matrix scheme in the thin boundary approximation. ...

  19. Inquiry-Based Examination of Chemical Disruption of Bacterial Biofilms

    Science.gov (United States)

    Redelman, Carly V.; Hawkins, Misty A. W.; Drumwright, Franklin R.; Ransdell, Beverly; Marrs, Kathleen; Anderson, Gregory G.

    2012-01-01

    Inquiry-based instruction in the sciences has been demonstrated as a successful educational strategy to use for both high school and college science classrooms. As participants in the NSF Graduate STEM Fellows in K-12 Education (GK-12) Program, we were tasked with creating novel inquiry-based activities for high school classrooms. As a way to…

  20. 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

  1. Gardner定时同步环路参数设计及性能分析%Parameters design and performance analysis of the timing recovery loop based on Gardner timing detector

    Institute of Scientific and Technical Information of China (English)

    付永明; 朱江; 琚瑛珏

    2012-01-01

    In-depth research was carried out into parameters design in the feedback timing recovery loop based on Gardner timing error detector,according to the theory of digital phase-lock loop. MATLAB based simulation was performed for both first-order and second-order loop. Comprehensive analysis of the influence from loop order and noise- equivalent bandwidth on synchronization performance indicates the relationship between synchronization performance and noise-equivalent bandwidth,which provides a theoretic reference for timing recovery loop design.%以数字锁相环理论为依据,对Gardner定时误差检测器反馈定时环路参数的设计进行了深入研究,基于MATLAB对一阶、二阶环路性能进行了仿真,重点分析了环路阶数和等效噪声带宽对系统性能的影响,得到了等效噪声带宽与定时同步环路性能的关系,为定时同步环路的设计提供了理论依据.

  2. 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.

  3. PI Closed-Loop Feedback Terminal Voltage Control Scheme based on Static VAR Compensator for Three-Phase Self-Excited Induction Generator

    Science.gov (United States)

    Ahmed, Tarek; Noro, Osamu; Nakaoka, Mutsuo

    In this paper, the practical impedance approach steady-state analysis in the frequency domain of the three-phase self-excited induction generator (SEIG) with a squirrel cage rotor is presented, along with its operating performance evaluations. The three-phase SEIG is driven by a variable-speed prime mover (VSPM) in addition to a constant-speed prime mover (CSPM) such as a wind turbine and a micro gas turbine for the clean alternative renewable energy in rural areas. The basic steady-state characteristics of the VSPM are considered in the three-phase SEIG approximate electro-mechanical equivalent circuit and the operating performances of the three-phase SEIG coupled by a VSPM and/or a CSPM in the steady-state analysis are evaluated and discussed on line under the conditions related to the speed changes of the prime mover and the electrical inductive load power variations with simple computation processing procedures. A three-phase SEIG prototype setup with a VSPM as well as a CSPM is implemented for the small-scale clean renewable and alternative energy utilizations. The experimental performance results give good agreements with those ones obtained from the simulation results. Furthermore, a PI controlled feedback closed-loop voltage regulation of the three-phase SEIG driven by the VSPM on the basis of the static VAR compensator (SVC) composed of the thyristor phase controlled reactor (TCR) in parallel with the thyristor switched capacitor (TSC) and the fixed excitation capacitor bank (FC) is designed and considered for the wind generation as a renewable power conditioner. The simulation analysis and experimental results obtained from the three-phase SEIG with the SVC for its voltage regulation prove the practical effectiveness of the additional SVC with the PI controller-based feedback loop in the steady-state operations in terms of the fast response and the high performances.

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

    International Nuclear Information System (INIS)

    Highlights: • Full material characterization as far as hydrogen transport properties are concern. • Quantification of permeator leaks and material degasification. • Analysis of H2 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

  5. Qingtongxia Aluminum Carrying Out Off-site Renovation in Ningdong Energy & Chemical Base

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Recently,the off-site renovation project of Qingtongxia Aluminum commenced the con- struction in Linhe General Industrial Park of Ningdong Energy & Chemical Base,symboliz- ing a concrete step of Qingtongxia Aluminum

  6. CHEMICALLY MODIFIED FIELD-EFFECT TRANSISTORS - POTENTIOMETRIC AG+ SELECTIVITY OF PVC MEMBRANES BASED ON MACROCYCLIC THIOETHERS

    NARCIS (Netherlands)

    BRZOZKA, Z; COBBEN, PLHM; REINHOUDT, DN; EDEMA, JJH; KELLOGG, RM

    1993-01-01

    A chemically modified field-effect transistor (CHEMFET) with satisfactory Ag+ selectivity is described. The potentiometric Ag+ selectivities of CHEMFETs with plasticized PVC membranes based on macrocyclic thioethers have been determined. All the macrocyclic thioethers tested showed silver response a

  7. Application of chemical mechanical polishing process on titanium based implants.

    Science.gov (United States)

    Ozdemir, Z; Ozdemir, A; Basim, G B

    2016-11-01

    Modification of the implantable biomaterial surfaces is known to improve the biocompatibility of metallic implants. Particularly, treatments such as etching, sand-blasting or laser treatment are commonly studied to understand the impact of nano/micro roughness on cell attachment. Although, the currently utilized surface modification techniques are known to improve the amount of cell attachment, it is critical to control the level of attachment due to the fact that promotion of bioactivity is needed for prosthetic implants while the cardiac valves, which are also made of titanium, need demotion of cells attachment to be able to function. In this study, a new alternative is proposed to treat the implantable titanium surfaces by chemical mechanical polishing (CMP) technique. It is demonstrated that the application of CMP on the titanium surface helps in modifying the surface roughness of the implant in a controlled manner (inducing nano-scale smoothness or controlled nano/micro roughness). Simultaneously, it is observed that the application of CMP limits the bacteria growth by forming a protective thin surface oxide layer on titanium implants. It is further shown that there is an optimal level of surface roughness where the cell attachment reaches a maximum and the level of roughness is controllable through CMP. PMID:27524033

  8. Analysis of Thermal Desorption System for the Chemical Treatment of Old Storages of Oil Based Mud

    OpenAIRE

    Tanweer Hussain; Abdul Rehman Memon; Javed Larik

    2013-01-01

    This paper presents an analysis for the chemical treatment of OBM (Oil Based Mud) used in the drilling process in the oil and gas industry. The analysis is based on OBM stored at ENI (Italian National Energy) gas fields at Bhit mount district Jamshoro since the last ten years that has been chemically and physically deteriorated. Characterization of various OBM samples was performed and these samples were processed in order to evaluate the best characteristics of the OBM for optimum treatment ...

  9. Mindfulness-based cognitive therapy for multiple chemical sensitivity

    DEFF Research Database (Denmark)

    Hauge, Christian R; Bonde, Jens Peter E; Rasmussen, Alice;

    2012-01-01

    no evidence-based treatments for MCS. Nevertheless, there is a substantial need for a treatment, because the condition can be severely disabling and can greatly reduce the quality of life (QOL) for those affected.In this study, we aim to assess the effects of a mindfulness-based cognitive therapy (MBCT.......5 hour sessions, and 45 minutes of mindfulness home practice 6 days each week. Participants will be asked to complete questionnaires at baseline, post-treatment, and at 6 and 12 months' follow-up. Based on sample size estimation, 82 participants will be randomized to either the MBCT intervention...... is mediated by level of mindfulness, perceived stress, and rumination. DISCUSSION: This trial will provide important information on the effects of MBCT on MCS.Trials registrationClinical trials identifier NCT01240395....

  10. Advances and trends in ionophore-based chemical sensors

    Science.gov (United States)

    Mikhelson, K. N.; Peshkova, M. A.

    2015-06-01

    The recent advances in the theory and practice of potentiometric, conductometric and optical sensors based on ionophores are critically reviewed. The role of the heterogeneity of the sensor/sample systems is emphasized, and it is shown that due to this heterogeneity such sensors respond to the analyte activities rather than to concentrations. The basics of the origin of the response of all three kinds of ionophore-based sensors are briefly described. The use of novel sensor materials, new preparation and application techniques of the sensors as well as advances in theoretical treatment of the sensor response are analyzed using literature sources published mainly from 2012 to 2014. The basic achievements made in the past are also addressed when necessary for better understanding of the trends in the field of ionophore-based sensors. The bibliography includes 295 references.

  11. Paper-based chemical and biological sensors: Engineering aspects.

    Science.gov (United States)

    Ahmed, Snober; Bui, Minh-Phuong Ngoc; Abbas, Abdennour

    2016-03-15

    Remarkable efforts have been dedicated to paper-based chemosensors and biosensors over the last few years, mainly driven by the promise of reaching the best trade-off between performance, affordability and simplicity. Because of the low-cost and rapid prototyping of these sensors, recent research has been focused on providing affordable diagnostic devices to the developing world. The recent progress in sensitivity, multi-functionality and integration of microfluidic paper-based analytical devices (µPADs), increasingly suggests that this technology is not only attractive in resource-limited environments but it also represents a serious challenger to silicon, glass and polymer-based biosensors. This review discusses the design, chemistry and engineering aspects of these developments, with a focus on the past few years.

  12. Semiconductor device-based sensors for gas, chemical, and biomedical applications

    CERN Document Server

    Ren, Fan

    2011-01-01

    Sales of U.S. chemical sensors represent the largest segment of the multi-billion-dollar global sensor market, which includes instruments for chemical detection in gases and liquids, biosensors, and medical sensors. Although silicon-based devices have dominated the field, they are limited by their general inability to operate in harsh environments faced with factors such as high temperature and pressure. Exploring how and why these instruments have become a major player, Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications presents the latest research, including or

  13. Bent helix formation between RNA hairpins with complementary loops.

    Science.gov (United States)

    Marino, J P; Gregorian, R S; Csankovszki, G; Crothers, D M

    1995-06-01

    The initial interaction between the ColE1 plasmid specific transcripts RNA I and RNA II, which function as antisense regulators of plasmid replication, comprises a transient complex between complementary loops found within the RNA secondary structures. Multidimensional heteronuclear magnetic resonance spectroscopy was used to characterize complexes formed between model RNA hairpins having seven nucleotide complementary loops. Seven base pairs are formed in the loop-loop helix, with continuous helical stacking of the loop residues on the 3' side of their helical stems. A sharp bend in the loop-loop helix, documented by gel electrophoresis, narrows the major groove and allows bridging of the phosphodiester backbones across the major groove in order to close the hairpin loops at their 5'-ends. The bend is further enhanced by the binding of Rom, a ColE1 encoded protein that regulates replication. PMID:7539549

  14. COMPUTER SIMULATION OP FRANK LOOP CONTRAST IN FIELD IONIMAGES

    Energy Technology Data Exchange (ETDEWEB)

    Stolt, Kaj Gunnar

    1973-09-01

    A computer model for simulation of the image contrast caused by Frank dislocation loops in field ion tips of fcc materials is presented. The model is based on the shell model for ion image simulation, whereas the displacement field of Frank loops is computed from the exact displacement equation for a closed dislocation loop in an isotropically elastic continuum. A method for taking surface effects into account by superposition of the displacement field of an image loop is introduced. The results indicate that Frank loops will cause image contrast while wholly beneath the surface of the tip, and that vacancy and interstitial loops will cause qualitatively different contrast. The effect of surface relaxation, while quantitatively substantial, does not qualitatively alter these results. Special emphasis is placed on small loops, with respect to which existing contrast theory is inadequate. Some micrographs of ion bombarded iridium tips are presented. These micrographs display contrast effects in excellent agreement with computer plots of interstitial loop contrast.

  15. Natively unstructured loops differ from other loops.

    Directory of Open Access Journals (Sweden)

    Avner Schlessinger

    2007-07-01

    Full Text Available Natively unstructured or disordered protein regions may increase the functional complexity of an organism; they are particularly abundant in eukaryotes and often evade structure determination. Many computational methods predict unstructured regions by training on outliers in otherwise well-ordered structures. Here, we introduce an approach that uses a neural network in a very different and novel way. We hypothesize that very long contiguous segments with nonregular secondary structure (NORS regions differ significantly from regular, well-structured loops, and that a method detecting such features could predict natively unstructured regions. Training our new method, NORSnet, on predicted information rather than on experimental data yielded three major advantages: it removed the overlap between testing and training, it systematically covered entire proteomes, and it explicitly focused on one particular aspect of unstructured regions with a simple structural interpretation, namely that they are loops. Our hypothesis was correct: well-structured and unstructured loops differ so substantially that NORSnet succeeded in their distinction. Benchmarks on previously used and new experimental data of unstructured regions revealed that NORSnet performed very well. Although it was not the best single prediction method, NORSnet was sufficiently accurate to flag unstructured regions in proteins that were previously not annotated. In one application, NORSnet revealed previously undetected unstructured regions in putative targets for structural genomics and may thereby contribute to increasing structural coverage of large eukaryotic families. NORSnet found unstructured regions more often in domain boundaries than expected at random. In another application, we estimated that 50%-70% of all worm proteins observed to have more than seven protein-protein interaction partners have unstructured regions. The comparative analysis between NORSnet and DISOPRED2 suggested

  16. Natively unstructured loops differ from other loops.

    Science.gov (United States)

    Schlessinger, Avner; Liu, Jinfeng; Rost, Burkhard

    2007-07-01

    Natively unstructured or disordered protein regions may increase the functional complexity of an organism; they are particularly abundant in eukaryotes and often evade structure determination. Many computational methods predict unstructured regions by training on outliers in otherwise well-ordered structures. Here, we introduce an approach that uses a neural network in a very different and novel way. We hypothesize that very long contiguous segments with nonregular secondary structure (NORS regions) differ significantly from regular, well-structured loops, and that a method detecting such features could predict natively unstructured regions. Training our new method, NORSnet, on predicted information rather than on experimental data yielded three major advantages: it removed the overlap between testing and training, it systematically covered entire proteomes, and it explicitly focused on one particular aspect of unstructured regions with a simple structural interpretation, namely that they are loops. Our hypothesis was correct: well-structured and unstructured loops differ so substantially that NORSnet succeeded in their distinction. Benchmarks on previously used and new experimental data of unstructured regions revealed that NORSnet performed very well. Although it was not the best single prediction method, NORSnet was sufficiently accurate to flag unstructured regions in proteins that were previously not annotated. In one application, NORSnet revealed previously undetected unstructured regions in putative targets for structural genomics and may thereby contribute to increasing structural coverage of large eukaryotic families. NORSnet found unstructured regions more often in domain boundaries than expected at random. In another application, we estimated that 50%-70% of all worm proteins observed to have more than seven protein-protein interaction partners have unstructured regions. The comparative analysis between NORSnet and DISOPRED2 suggested that long

  17. On the Chemical Emergence of Phosphate-Based Biochemistry

    Science.gov (United States)

    Kee, Terence

    Contemporary organisms use orthophosphate derivatives (PO43-) in their cell biochemistry,1 yet questions remain as to how Nature was able to accumulate, activate and exploit the or-thophosphate group from geological sources with both poorly solubility and low chemical activ-ity.2 Gulick argued3 a central role for reduced oxidation state phosphorus (P) oxyacids such as H-phosphonates (H2PO3-) and especially H-phosphinates (H2PO2-) in prebiotic chemistry on account of the greater water solubility of their metal salts and, with the presence of P-H bonds, a different reactivity profile to that expected of orthophosphate. The recent demonstration that hydrothermal corrosion of P-rich mineral phases such as schreibersite (Fe,Ni)3P within iron meteorites leads to production of various P-oxyacids including H-phosphonic (H3PO3)4 and H-phosphinic5 acids as well as orthophosphate has reignited interest in reduced oxida-tion state P chemistry in prebiotic environments. We are examining the prebiotic potential of reduced oxidation state P-chemistry through reactions with carbonyl substrates with rea-sonable prebiotic provenance including formaldehyde glycolaldehyde, both intimately involved in the formose reaction for sugar synthesis6 and pyruvic acid,7 a product of glycolysis and feed-stock for the citric acid cycle, a fundamental cellular metablic process whose heritage is considered an ancient one. In this contribution we present some of our latest results on the H-phosphinate-pyruvate system. References: [1] Lodish H et al. (2000) Molecular Cell Biology, 4th Ed., W. H. Freeman Co., New York. [2] Gulick A. (1955) Am. Sci., 43, 479. [3] Gulick A. (1957) Ann. N. Y. Acad. Sci. 69, 309. [4] Pasek M. A. (2008) Proc. Nat. Acad. Sci. USA, 105, 853. [5] Bryant D. E.and Kee T. P. (2006) Chem. Commun. 2344. [6] Weber A. L. (2000) Origins of Life and Evol. Biosph., 30, 33. [7] Cody G. D. et. al. (2000) Science 289, 1337.

  18. The EDKB: an established knowledge base for endocrine disrupting chemicals

    OpenAIRE

    Bearden Edward D; Harris Steve; Perkins Roger; Hong Huixiao; Fang Hong; Xu Lei; Ding Don; Shi Leming; Tong Weida

    2010-01-01

    Abstract Background Endocrine disruptors (EDs) and their broad range of potential adverse effects in humans and other animals have been a concern for nearly two decades. Many putative EDs are widely used in commercial products regulated by the Food and Drug Administration (FDA) such as food packaging materials, ingredients of cosmetics, medical and dental devices, and drugs. The Endocrine Disruptor Knowledge Base (EDKB) project was initiated in the mid 1990’s by the FDA as a resource for the ...

  19. The structure of the isolated, central hairpin of the HDV antigenomic ribozyme: novel structural features and similarity of the loop in the ribozyme and free in solution.

    Science.gov (United States)

    Kolk, M H; Heus, H A; Hilbers, C W

    1997-01-01

    The structure of an RNA hairpin containing a seven-nucleotide loop that is present in the self-cleaving sequence of hepatitis delta virus antigenomic RNA was determined by high resolution NMR spectroscopy. The loop, which is composed of only one purine and six pyrimidines, has a suprisingly stable structure, mainly supported by sugar hydroxyl hydrogen bonds and base-base and base-phosphate stacking interactions. Compared with the structurally well-determined, seven-membered anticodon loop in tRNA, the sharp turn which affects the required 180 degrees change in direction of the sugar-phosphate backbone in the loop is shifted one nucleotide in the 3' direction. This change in direction can be characterized as a reversed U-turn. It is expected that the reversed U-turn may be found frequently in other molecules as well. There is evidence for a new non-Watson-Crick UC base pair formed between the first and the last residue in the loop, while most of the other bases in the loop are pointing outwards making them accessible to solvent. From chemical modification, mutational and photocrosslinking studies, a similar picture develops for the structure of the hairpin in the active ribozyme indicating that the loop structure in the isolated hairpin and in the ribozyme is very similar. PMID:9218809

  20. Learning Loops--Interactions between Guided Reflection and Experience-Based Learning in a Serious Game Activity

    Science.gov (United States)

    Cowley, B.; Heikura, T.; Ravaja, N.

    2013-01-01

    In a study on experience-based learning in serious games, 45 players were tested for topic comprehension by a questionnaire administered before and after playing the single-player serious game Peacemaker (Impact Games 2007). Players were divided into two activity conditions: 20 played a 1-h game with a 3-min half-time break to complete an affect…