WorldWideScience

Sample records for based working fluids

  1. Evaluation of Working Fluids for Organic Rankine Cycle Based on Exergy Analysis

    Science.gov (United States)

    Setiawan, D.; Subrata, I. D. M.; Purwanto, Y. A.; Tambunan, A. H.

    2018-05-01

    One of the crucial aspects to determine the performance of Organic Rankine Cycle (ORC) is the selection of appropriate working fluids. This paper describes the simulative performance of several organic fluid and water as working fluid of an ORC based on exergy analysis with a heat source from waste heat recovery. The simulation was conducted by using Engineering Equation Solver (EES). The effect of several parameters and thermodynamic properties of working fluid was analyzed, and part of them was used as variables for the simulation in order to determine their sensitivity to the exergy efficiency changes. The results of this study showed that water is not appropriate to be used as working fluid at temperature lower than 130 °C, because the expansion process falls in saturated area. It was also found that Benzene had the highest exergy efficiency, i.e. about 10.49%, among the dry type working fluid. The increasing turbine inlet temperature did not lead to the increase of exergy efficiency when using organic working fluids with critical temperature near heat source temperature. Meanwhile, exergy efficiency decreasing linearly with the increasing condenser inlet temperature. In addition, it was found that working fluid with high latent heat of vaporization and specific heat exert in high exergy efficiency.

  2. The interior working mechanism and temperature characteristics of a fluid based micro-vibration isolator

    Science.gov (United States)

    Wang, Jie; Zhao, Shougen; Wu, Dafang; Jing, Xingjian

    2016-01-01

    Micro-vibration isolation is a hot topic in spacecraft vibration control, and fluid based vibration isolators alternatively provide a good and reliable solution to this challenging issue. In this paper, a novel fluid based micro-vibration isolator (FBMVI) is investigated. According to its inherent working principle and deformation pattern, the generation mechanisms of the damping and stiffness characteristics are derived, which are nonlinear functions of the environmental temperature. Then a lumped parameter model which is expressed by the physical design parameters (PDPs) is constructed, and the corresponding performance objective indices (POIs) are also obtained by applying the equivalence of mechanical impedance. Based on the finite element analysis of the internal damping component, a single variable method is further adopted to carry out the parametric study, and the influences of each PDP on the POIs are analyzed in details. Finally, experiments are conducted to identify the variation of fluid bulk modulus with the outside environmental temperature, and to validate the performance of the isolator under different temperature environments. The tested results show great consistence compared with the predicted tendencies of the parametric study. The results of this study can provide a very useful insight into and/or an important guidance for the design and application of this type of FBMVIs in engineering practice.

  3. Hazards of organic working fluids

    International Nuclear Information System (INIS)

    Silberstein, S.

    1977-08-01

    We present several brief reviews on working fluids proposed for use in organic Rankine and bi-phase bottoming cycles. There are several general problems with many organic working fluids: flammability, toxicity, and a tendency to leak through seals. Besides, two of the proposed working fluids are to be used at temperatures above the manufacturer's maximum recommended temperature, and one is to be used in a way different from its customary usage. It may, in some cases, be more profitable to first seek alternative working fluids before committing large amounts of time and money to research projects on unsafe working fluids

  4. A new method used to evaluate organic working fluids

    International Nuclear Information System (INIS)

    Zhang, Xinxin; He, Maogang; Wang, Jingfu

    2014-01-01

    In this paper, we propose a method named “Weight Classification-Hasse Dominance” to evaluate organic working fluids. This new method combines the advantages of both the method of weight determination and the Hasse Diagram Technique (HDT). It can be used to evaluate the thermodynamic performance, environmental protection indicator, and safety requirement of organic working fluid simultaneously. This evaluation method can offer good reference for working fluid selection. Using this method, the organic working fluids which have been phased out and will be phased out by the Montreal Protocol including CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), and HFCs (hydrofluorocarbons) were evaluated. Moreover, HCs (hydrocarbons) can be considered as a completely different kind of organic working fluid from CFCs, HCFCs, and HFCs according to the comparison based on this new evaluation method. - Highlights: • We propose a new method used to evaluate organic working fluids. • This evaluation method can offer good reference for working fluid selection. • CFC, HCFC, and HFC working fluids were evaluated using this evaluation method. • HC can be considered as a totally different working fluid from CFC, HCFC, and HFC

  5. Closed-cycle gas turbine working fluids

    International Nuclear Information System (INIS)

    Lee, J.C.; Campbell, J. Jr.; Wright, D.E.

    1981-01-01

    Characteristic requirements of a closed-cycle gas turbine (CCGT) working fluid were identified and the effects of their thermodynamic and transport properties on the CCGT cycle performance, required heat exchanger surface area and metal operating temperature, cycle operating pressure levels, and the turbomachinery design were investigated. Material compatibility, thermal and chemical stability, safety, cost, and availability of the working fluid were also considered in the study. This paper also discusses CCGT working fluids utilizing mixtures of two or more pure gases. Some mixtures of gases exhibit pronounced synergetic effects on their characteristic properties including viscosity, thermal conductivity and Prandtl number, resulting in desirable heat transfer properties and high molecular weights. 21 refs

  6. Stirling engine with air working fluid

    Science.gov (United States)

    Corey, John A.

    1985-01-01

    A Stirling engine capable of utilizing air as a working fluid which includes a compact heat exchange module which includes heating tube units, regenerator and cooler positioned about the combustion chamber. This arrangement has the purpose and effect of allowing the construction of an efficient, high-speed, high power-density engine without the use of difficult to seal light gases as working fluids.

  7. Selection of working fluids for a novel low-temperature geothermally-powered ORC based cogeneration system

    International Nuclear Information System (INIS)

    Guo, T.; Wang, H.X.; Zhang, S.J.

    2011-01-01

    Highlights: → Performances of a novel cogeneration system using low-temperature geothermal sources under disturbance conditions were investigated. → It aimed at identifying appropriate fluids yielding high PPR and QQR values. → Fluids group presenting higher normal boiling point values showed averagely 7.7% higher PPR with a larger variation than QQR values under disturbance conditions. → Smaller T P value, higher η t value, higher geothermal source parameters and lower heating supply parameters led to higher PPR values but lower QQR values. -- Abstract: A novel cogeneration system driven by low-temperature geothermal sources was investigated in this study. This system consists of a low-temperature geothermally-powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger and a commercial R134a-based heat pump subsystem. The main purpose is to identify appropriate fluids which may yield high PPR (the ratio of power produced by the power generation subsystem to power consumed by the heat pump subsystem) value and QQR (the ratio of heat supplied to the user to heat produced by the geothermal source) value. Performances of the novel cogeneration system under disturbance conditions have also been studied. Results indicate that fluids group presenting higher normal boiling point values shows averagely 7.7% higher PPR values and R236ea and R245ca outstand among the group. ΔT P (pinch temperature difference in heat exchangers) and η t (turbine efficiency) values play more important roles on the variation of PPR values. QQR values change slightly with various ΔT P , η t and η rp (refrigerant pump efficiency) values while the variation range is larger under various geothermal source and heating supply parameters. Smaller ΔT P value, higher η t value, higher geothermal source parameters and lower heating supply parameters lead to higher PPR values but lower QQR values.

  8. Performance analysis of organic Rankine cycles using different working fluids

    Directory of Open Access Journals (Sweden)

    Zhu Qidi

    2015-01-01

    Full Text Available Low-grade heat from renewable or waste energy sources can be effectively recovered to generate power by an organic Rankine cycle (ORC in which the working fluid has an important impact on its performance. The thermodynamic processes of ORCs using different types of organic fluids were analyzed in this paper. The relationships between the ORC’s performance parameters (including evaporation pressure, condensing pressure, outlet temperature of hot fluid, net power, thermal efficiency, exergy efficiency, total cycle irreversible loss, and total heat-recovery efficiency and the critical temperatures of organic fluids were established based on the property of the hot fluid through the evaporator in a specific working condition, and then were verified at varied evaporation temperatures and inlet temperatures of the hot fluid. Here we find that the performance parameters vary monotonically with the critical temperatures of organic fluids. The values of the performance parameters of the ORC using wet fluids are distributed more dispersedly with the critical temperatures, compared with those of using dry/isentropic fluids. The inlet temperature of the hot fluid affects the relative distribution of the exergy efficiency, whereas the evaporation temperature only has an impact on the performance parameters using wet fluid.

  9. Compression in Working Memory and Its Relationship With Fluid Intelligence.

    Science.gov (United States)

    Chekaf, Mustapha; Gauvrit, Nicolas; Guida, Alessandro; Mathy, Fabien

    2018-06-01

    Working memory has been shown to be strongly related to fluid intelligence; however, our goal is to shed further light on the process of information compression in working memory as a determining factor of fluid intelligence. Our main hypothesis was that compression in working memory is an excellent indicator for studying the relationship between working-memory capacity and fluid intelligence because both depend on the optimization of storage capacity. Compressibility of memoranda was estimated using an algorithmic complexity metric. The results showed that compressibility can be used to predict working-memory performance and that fluid intelligence is well predicted by the ability to compress information. We conclude that the ability to compress information in working memory is the reason why both manipulation and retention of information are linked to intelligence. This result offers a new concept of intelligence based on the idea that compression and intelligence are equivalent problems. Copyright © 2018 Cognitive Science Society, Inc.

  10. Fluid discrimination based on rock physics templates

    International Nuclear Information System (INIS)

    Liu, Qian; Yin, Xingyao; Li, Chao

    2015-01-01

    Reservoir fluid discrimination is an indispensable part of seismic exploration. Reliable fluid discrimination helps to decrease the risk of exploration and to increase the success ratio of drilling. There are many kinds of fluid indicators that are used in fluid discriminations, most of which are single indicators. But single indicators do not always work well under complicated reservoir conditions. Therefore, combined fluid indicators are needed to increase accuracies of discriminations. In this paper, we have proposed an alternative strategy for the combination of fluid indicators. An alternative fluid indicator, the rock physics template-based indicator (RPTI) has been derived to combine the advantages of two single indicators. The RPTI is more sensitive to the contents of fluid than traditional indicators. The combination is implemented based on the characteristic of the fluid trend in the rock physics template, which means few subjective factors are involved. We also propose an inversion method to assure the accuracy of the RPTI input data. The RPTI profile is an intuitionistic interpretation of fluid content. Real data tests demonstrate the applicability and validity. (paper)

  11. Parametric investigation of working fluids for organic Rankine cycle applications

    International Nuclear Information System (INIS)

    Brown, J. Steven; Brignoli, Riccardo; Quine, Timothy

    2015-01-01

    This paper investigates working fluids for organic Rankine cycle (ORC) applications with a goal of identifying “ideal” working fluids for five renewable/alternative energy sources. It employs a methodology for screening and comparing with good engineering accuracy the thermodynamic performance potential of ORC operating with working fluids that are not well characterized experimentally or by high-accuracy equations of state. A wide range of “theoretical” working fluids are investigated with the goals to identify potential alternative working fluids and to guide future research and development efforts of working fluids. The “theoretical” working fluids investigated are described in terms of critical state properties, acentric factor, and ideal gas specific heat capacity at constant pressure and are obtained by parametrically varying each of these parameters. The performances of these “theoretical” working fluids are compared to the performances of several “real” working fluids. The study suggests a working fluid's critical temperature and its critical ideal gas molar heat capacity have the largest impact on the cycle efficiency and volumetric work output, with “ideal” working fluids for high efficiency possessing critical temperatures on the order of 100%–150% of the source temperature and possessing intermediate values of critical ideal gas molar heat capacity. - Highlights: • “Ideal” working fluids are investigated for organic Rankine cycles (ORC). • The thermodynamic space of “ideal” working fluids is parametrically investigated. • Five low- and high-temperature ORC applications are investigated. • 1620 “ideal” and several “real” working fluids per application are investigated.

  12. Dust as a Working Fluid for Heat Transfer Project

    Science.gov (United States)

    Mantovani, James G.

    2015-01-01

    The project known as "Dust as a Working Fluid" demonstrates the feasibility of a dust-based system for transferring heat radiatively into space for those space applications requiring higher efficiency, lower mass, and the need to operate in extreme vacuum and thermal environments - including operating in low or zero gravity conditions in which the dust can be conveyed much more easily than on Earth.

  13. Working fluid selection for organic Rankine cycles - Impact of uncertainty of fluid properties

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Andreasen, Jesper Graa; Liu, Wei

    2016-01-01

    of processmodels and constraints 2) selection of property models, i.e. Penge Robinson equation of state 3)screening of 1965 possible working fluid candidates including identification of optimal process parametersbased on Monte Carlo sampling 4) propagating uncertainty of fluid parameters to the ORC netpower output......This study presents a generic methodology to select working fluids for ORC (Organic Rankine Cycles)taking into account property uncertainties of the working fluids. A Monte Carlo procedure is described as a tool to propagate the influence of the input uncertainty of the fluid parameters on the ORC....... The net power outputs of all the feasible working fluids were ranked including their uncertainties. The method could propagate and quantify the input property uncertainty of the fluidproperty parameters to the ORC model, giving an additional dimension to the fluid selection process. In the given analysis...

  14. Thermophysical Properties of Aqueous Solutions Used as Secondary Working Fluids

    OpenAIRE

    Melinder, Åke

    2007-01-01

    Secondary working fluids (secondary refrigerants, heat transfer fluids, antifreezes, brines) have long been used in various indirect re-frigeration and heat pump systems. Aqueous solutions (water solu-tions) have long been used as single phase (liquid only) secondary working fluids for cooling in supermarkets, ice rinks, heat recovery systems, heat pumps and other applications. However, aqueous solutions are increasingly used also for freezers in supermarkets and other applications in low tem...

  15. Working fluid selection for organic Rankine cycles - Impact of uncertainty of fluid properties

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Andreasen, Jesper Graa; Liu, Wei

    2016-01-01

    This study presents a generic methodology to select working fluids for ORC (Organic Rankine Cycles)taking into account property uncertainties of the working fluids. A Monte Carlo procedure is described as a tool to propagate the influence of the input uncertainty of the fluid parameters on the ORC...... modeloutput, and provides the 95%-confidence interval of the net power output with respect to the fluid property uncertainties. The methodology has been applied to a molecular design problem for an ORCusing a low-temperature heat source and consisted of the following four parts: 1) formulation...... of processmodels and constraints 2) selection of property models, i.e. Penge Robinson equation of state 3)screening of 1965 possible working fluid candidates including identification of optimal process parametersbased on Monte Carlo sampling 4) propagating uncertainty of fluid parameters to the ORC netpower output...

  16. Theoretical aspects concerning working fluids in hydraulic systems

    Directory of Open Access Journals (Sweden)

    Tița Irina

    2017-01-01

    Full Text Available Among the properties of working fluid, viscosity is the most important as it regards especially to pumps. In order to study the behavior of hydrostatic transmission it is important to create a reliable research instrument for dynamic simulation. Our research expertise being in SimHydraulics consequently this instrument is the suitable block diagram. The purpose of this paper is to present the possible ways to customize the properties of the working fluid in the block diagram.

  17. Molecular Entropy, Thermal Efficiency, and Designing of Working Fluids for Organic Rankine Cycles

    Science.gov (United States)

    Wang, Jingtao; Zhang, Jin; Chen, Zhiyou

    2012-06-01

    A shortage of fossil energy sources boosts the utilization of renewable energy. Among numerous novel techniques, recovering energy from low-grade heat sources through power generation via organic Rankine cycles (ORCs) is one of the focuses. Properties of working fluids are crucial for the ORC's performance. Many studies have been done to select proper working fluids or to design new working fluids. However, no researcher has systematically investigated the relationship between molecular structures and thermal efficiencies of various working fluids for an ideal ORC. This paper has investigated the interrelations of molecular structures, molecular entropies, and thermal efficiencies of various working fluids for an ideal ORC. By calculating thermal efficiencies and molecular entropies, we find that the molecular entropy is the most appropriate thermophysical property of a working fluid to determine how much energy can be converted into work and how much cannot in a system. Generally speaking, working fluids with low entropies will generally have high thermal efficiency for an ideal ORC. Based on this understanding, the direct interrelations of molecular structures and entropies provide an explicit interrelation between molecular structures and thermal efficiencies, and thus provide an insightful direction for molecular design of novel working fluids for ORCs.

  18. High Temperature Heat Pump Integration using Zeotropic Working Fluids for Spray Drying Facilities

    DEFF Research Database (Denmark)

    Zühlsdorf, Benjamin; Bühler, Fabian; Mancini, Roberta

    2017-01-01

    source and sink best possibly. Therefore, a set of six common working fluids is defined and the possible binary mixtures of these fluids are analyzed. The performance of the fluids is evaluated based on the energetic performance (COP) and the economic potential (NPV). The results show...... and show a large potential to reuse the excess heat from exhaust gases. This study analyses a heat pump application with an improved integration by choosing the working fluid as a mixture in such a way, that the temperature glide during evaporation and condensation matches the temperature glide of the heat...

  19. Working Fluids for Increasing Capacities of Heat Pipes

    Science.gov (United States)

    Chao, David F.; Zhang, Nengli

    2004-01-01

    A theoretical and experimental investigation has shown that the capacities of heat pipes can be increased through suitable reformulation of their working fluids. The surface tensions of all of the working fluids heretofore used in heat pipes decrease with temperature. As explained in more detail below, the limits on the performance of a heat pipe are associated with the decrease in the surface tension of the working fluid with temperature, and so one can enhance performance by reformulating the working fluid so that its surface tension increases with temperature. This improvement is applicable to almost any kind of heat pipe in almost any environment. The heat-transfer capacity of a heat pipe in its normal operating-temperature range is subject to a capillary limit and a boiling limit. Both of these limits are associated with the temperature dependence of surface tension of the working fluid. In the case of a traditional working fluid, the decrease in surface tension with temperature causes a body of the liquid phase of the working fluid to move toward a region of lower temperature, thus preventing the desired spreading of the liquid in the heated portion of the heat pipe. As a result, the available capillary-pressure pumping head decreases as the temperature of the evaporator end of the heat pipe increases, and operation becomes unstable. Water has widely been used as a working fluid in heat pipes. Because the surface tension of water decreases with increasing temperature, the heat loads and other aspects of performance of heat pipes that contain water are limited. Dilute aqueous solutions of long-chain alcohols have shown promise as substitutes for water that can offer improved performance, because these solutions exhibit unusual surface-tension characteristics: Experiments have shown that in the cases of an aqueous solution of an alcohol, the molecules of which contain chains of more than four carbon atoms, the surface tension increases with temperature when the

  20. Operation characteristic of a R123-based organic Rankine cycle depending on working fluid mass flow rates and heat source temperatures

    International Nuclear Information System (INIS)

    Feng, Yong-Qiang; Hung, Tzu-Chen; Wu, Shang-Lun; Lin, Chih-Hung; Li, Bing-Xi; Huang, Kuo-Chen; Qin, Jiang

    2017-01-01

    Highlights: • The operation characteristic of an Organic Rankine Cycle using R123 and a scroll expander have been investigated. • The behaviors and detailed discussion for those four major components are examined. • The expander isentropic efficiency presents a slight decrease first and then a sharp increase with mass flow rate. • The maximum electrical power and system generation efficiency are 2.01 kW and 3.25%, respectively. - Abstract: The test and operation characteristic of an organic Rankine cycle using R123 and a scroll expander have been investigated. The steady-state operation characteristic is addressed with the varying working fluid mass flow rates ranging of 0.124–0.222 kg/s and heat source temperatures ranging of 383.15–413.15 K. The behaviors and detailed discussion for those four major components (pump, evaporator, expander and condenser) are examined. The experimental results show that the environmental temperature presents a higher influence on the pump behaviors. The range of pump power consumption, isentropic efficiency and back work ratio are 0.21–0.32 kW, 26.76–53.96%, and 14–32%, respectively. The expander isentropic efficiency presents a slight decrease first and then a sharp increase with mass flow rate, while a degree of superheating more than 3 K is necessary to avoid expander cavitation. The expander isentropic and generator efficiencies are in range of 69.10–85.17% and 60–73%, respectively, while the respective heat transfer coefficients for evaporator and condenser are ranging of 200–400 and 450–2000 W/m"2 K. The maximum expander shaft power and electrical power are 2.78 kW and 2.01 kW, respectively, while the maximum system generating efficiency is 3.25%. Moreover, the tested thermal efficiency presents a slight decrease trend with mass flow rate.

  1. FORMATE-BASED FLUIDS: FORMULATION AND APPLICATION

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2008-12-01

    Full Text Available Formate-based fluids has been successfully used in over hunders HPHT well operations since they introduced in field practice. They have many advantages when compared with conventional HPHT drilling and completion fluids such as: minimal formation damage, maintenance of additve properties at high temperatures, reduced hydraulic flow resistance, low potential for differential sticking, naturally lubricating, very low corrosion rates, biodegradable and pose little risk to the environment etc. Formate-based fluids can be applied during deep slim hole drilling, shale drilling, reservoir drilling, salt and gas hydrate formations drilling. The laboratory research was carried out to evaluate the rheological behavior of formate-based fluids as a function of temperature. Formate-based fluids were formulated using potassium formate brine, xanthan polymer, PAC, starch and calcium carbonate. Experimental results show that potassium formate improves the thermal stability of polymers.

  2. Natural working fluids for solar-boosted heat pumps

    Energy Technology Data Exchange (ETDEWEB)

    Chaichana, C.; Lu Aye [University of Melbourne, Victoria (Australia). International Technologies Centre, Department of Civil and Environmental Engineering; Charters, W.W.S. [University of Melbourne, Victoria (Australia). Department of Mechanical and Manufacturing Engineering

    2003-09-01

    The option of using natural working fluids as a substitute of R-22 for solar-boosted heat pumps depends not only upon thermal performance and hazardous rating but also on potential impacts on the environment. This paper presents the comparative assessment of natural working fluids with R-22 in terms of their characteristics and thermophysical properties, and thermal performance. Some justification is given for using natural working fluids in a solar boosted heat pump water heater. The results show that R-744 is not suitable for solar-boosted heat pumps because of its low critical temperature and high operational pressures. On the other hand, R-717 seems to be a more appropriate substitute in terms of operational parameters and overall performance. However, major changes in the heat pumps are required. R-290 and R-1270 are identified as candidates for direct drop-in substitutes for R-22. (author)

  3. New era for CO2 as a working fluid

    International Nuclear Information System (INIS)

    Stene, Joern

    2000-01-01

    During the past decade there has been extensive international activity to find acceptable alternatives to ozone-depleting CFC and HCFC substances that have been widely used as working fluids in refrigerating and heat pump plants. At present, the so-called natural working fluids constitute the most environmentally friendly alternative, and they include first of all ammonia, hydrocarbons and carbon dioxide (CO2). NTNU and SINTEF Energy Research, Norway, have been pioneers in the development of refrigerating and heat pump systems that use CO2 as a working fluid. The favourable technical and environmental properties of CO2 as well as the promising results have now led to considerable international interest in CO2 technology for refrigerating and heat pump applications. Two examples are international licensing for Norwegian CO2 technology and co-operation with Indonesia on CO2 for refrigeration

  4. A sealed turbo-alternator using any working-fluid

    International Nuclear Information System (INIS)

    Chollet, Maurice.

    1973-01-01

    The invention relates to a sealed turbo-alternator operating with a working fluid other than water. The turbo-alternator and the feed and lubricating pumps thereof are housed in a sealed casing. The latter constitutes, with the heat pump and the heat sink, a sealed enclosure containing the working and lubricating fluid. The alternator, which comprises neither collector nor brushes, is dipped in the working fluid vapor. Electric energy leaves the sealed enclosure through insulating sealed passager. In view of the absence of leakage it is possible to select (e.g. among freons) a working fluid well suited to the temperature differential between the heat source and the heat sink, and, accordingly to use temperature drops which could be too small in the case of steam. The various applications are as follows: recovery of calories at the exhaust of diesels and of gas turbines or in the cooling water of diesels; equipment of isotopic generators; recovery of calories from factory waste thrown into rivers (anti-pollution effect in view of the lowering of water temperature); non-polluting engine for special electrical vehicles [fr

  5. Tailored Working Fluids for Enhanced Binary Geothermal Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Ahmad [United Technologies Research Center, East Hartford, CT (United States)

    2013-01-29

    United Technologies Research Center (UTRC), in collaboration with the Georgia Institute of Technology and the National Institute of Standards and Technology will evaluate and develop fundamental and component level models, conduct experiments and generate data to support the use of mixed or enhanced working fluids for geothermal power generation applications.

  6. Working fluid charge oriented off-design modeling of a small scale Organic Rankine Cycle system

    International Nuclear Information System (INIS)

    Liu, Liuchen; Zhu, Tong; Ma, Jiacheng

    2017-01-01

    Highlights: • Organic Rankine Cycle model considering working fluid charge has been established. • Overall solution algorithm of system off-design performance is proposed. • Variation trend of different zones in both heat exchangers can be observed. • Optimal working fluid charge volume for different output work has been estimated. - Abstract: Organic Rankine Cycle system is one of the most widely used technique for low-grade waste heat recovery. Developing of dynamic Organic Rankine Cycle models played an increasingly important part in system performance prediction. The present paper developed a working fluid charge oriented model for an small scale Organic Rankine Cycle to calculate the theoretical value of working fluid charge level for the system under rated condition. The two heat exchangers are divided into three different zones and related heat transfer correlations are employed to estimate the length variation of each zones. Steady state models have been applied to describe the performance of pump and expander. Afterwards, an overall solution algorithm based on the established model has been proposed in order to exact simulate the system’s off-design performance. Additionally, the impact of different working fluid charge volumes has also been discussed. Simulation results clearly shows the variation trend of different zones in both heat exchangers, as well as the variation trend of system operating parameters under various expander output work. Furthermore, the highest thermal efficiency can be reached 6.37% under rated conditions with a working fluid charge volume of 34.6 kg.

  7. New knowledge on the temperature-entropy saturation boundary slope of working fluids

    International Nuclear Information System (INIS)

    Su, Wen; Zhao, Li; Deng, Shuai

    2017-01-01

    The slope of temperature-entropy saturation boundary of working fluids has a significant effect on the thermodynamic performance of cycle processes. However, for the working fluids used in cycles, few studies have been conducted to analyze the saturated slope from the molecular structure and mixture composition. Thus, in this contribution, an analytical expression on the slope of saturated curve is obtained based on the highly accurate Helmholtz energy equation. 14 pure working fluids and three typical binary mixtures are employed to analyze the influence of molecular groups and mixture compositions on the saturated slope, according to the correlated parameters of Helmholtz energy equation. Based on the calculated results, a preliminary trend is demonstrated that with an increase of the number of molecular groups, the positive liquid slope of pure fluids increases and the vapor slope appears positive sign in a narrow temperature range. Particularly, for the binary mixtures, the liquid slope is generally located between the corresponding pure fluids', while the vapor slope can be infinity by mixing dry and wet fluids ingeniously. It can be proved through the analysis of mixtures' saturated slope that three types of vapor slope could be obtained by regulating the mixture composition. - Highlights: • The saturated slope is derived from the Helmholtz function for working fluids. • The effect of molecular structure on the saturated slope is analyzed. • The variation of saturated slope with the mixture composition is investigated.

  8. Working Memory Capacity and Fluid Intelligence: Maintenance and Disengagement.

    Science.gov (United States)

    Shipstead, Zach; Harrison, Tyler L; Engle, Randall W

    2016-11-01

    Working memory capacity and fluid intelligence have been demonstrated to be strongly correlated traits. Typically, high working memory capacity is believed to facilitate reasoning through accurate maintenance of relevant information. In this article, we present a proposal reframing this issue, such that tests of working memory capacity and fluid intelligence are seen as measuring complementary processes that facilitate complex cognition. Respectively, these are the ability to maintain access to critical information and the ability to disengage from or block outdated information. In the realm of problem solving, high working memory capacity allows a person to represent and maintain a problem accurately and stably, so that hypothesis testing can be conducted. However, as hypotheses are disproven or become untenable, disengaging from outdated problem solving attempts becomes important so that new hypotheses can be generated and tested. From this perspective, the strong correlation between working memory capacity and fluid intelligence is due not to one ability having a causal influence on the other but to separate attention-demanding mental functions that can be contrary to one another but are organized around top-down processing goals. © The Author(s) 2016.

  9. Simulation based engineering in fluid flow design

    CERN Document Server

    Rao, J S

    2017-01-01

    This volume offers a tool for High Performance Computing (HPC). A brief historical background on the subject is first given. Fluid Statics dealing with Pressure in fluids at rest, Buoyancy and Basics of Thermodynamics are next presented. The Finite Volume Method, the most convenient process for HPC, is explained in one-dimensional approach to diffusion with convection and pressure velocity coupling. Adiabatic, isentropic and supersonic flows in quasi-one dimensional flows in axisymmetric nozzles is considered before applying CFD solutions. Though the theory is restricted to one-dimensional cases, three-dimensional CFD examples are also given. Lastly, nozzle flows with normal shocks are presented using turbulence models. Worked examples and exercises are given in each chapter. Fluids transport thermal energy for its conversion to kinetic energy, thus playing a major role that is central to all heat engines. With the advent of rotating machinery in the 20th century, Fluid Engineering was developed in the form o...

  10. Working memory training may increase working memory capacity but not fluid intelligence.

    Science.gov (United States)

    Harrison, Tyler L; Shipstead, Zach; Hicks, Kenny L; Hambrick, David Z; Redick, Thomas S; Engle, Randall W

    2013-12-01

    Working memory is a critical element of complex cognition, particularly under conditions of distraction and interference. Measures of working memory capacity correlate positively with many measures of real-world cognition, including fluid intelligence. There have been numerous attempts to use training procedures to increase working memory capacity and thereby performance on the real-world tasks that rely on working memory capacity. In the study reported here, we demonstrated that training on complex working memory span tasks leads to improvement on similar tasks with different materials but that such training does not generalize to measures of fluid intelligence.

  11. Clay-based geothermal drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Guven, N.; Carney, L.L.; Lee, L.J.; Bernhard, R.P.

    1982-11-01

    The rheological properties of fluids based on fibrous clays such as sepiolite and attapulgite have been systematically examined under conditions similar to those of geothermal wells, i.e. at elevated temperatures and pressures in environments with concentrated brines. Attapulgite- and sepiolite-based fluids have been autoclaved at temperatures in the range from 70 to 800/sup 0/F with the addition of chlorides and hydroxides of Na, K, Ca, and Mg. The rheological properties (apparent and plastic viscosity, fluid loss, gel strength, yield point, and cake thickness) of the autoclaved fluids have been studied and correlated with the chemical and physical changes that occur in the clay minerals during the autoclaving process.

  12. Characteristics of Plasma Probes in an MHD Working Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Whitman, A. M.; Hsuan, Yeh [Towne School of Civil and Mechanical Engineering, University of Pennsylvania (United States)

    1966-10-15

    In this paper an attempt is made to formulate a theory of electrostatic probes in a high-pressure plasma in which an external electrical field may be imposed. Such a situation exists in high-pressure arc discharges and in MHD channels. First, it is shown that an adequate theory must include the ionization and recombination phenomena which were ignored in almost all previous theories. Secondly, due to the preferred direction induced by the presence of the electric field, the probe problem is no longer a symmetrical one. The analysis is based on the assumption that the three-body recombination and ionization is the dominant process. In a typical MHD working fluid, say an argon gas seeded with caesium at 2000 Degree-Sign K and one atmosphere of pressure, the penetration length I of ions and electrons, i.e. the distance that an ion or electron diffuses before recombination, is of the order of 10{sup -3} cm. (It is to be noted that ambipolar diffusion prevents the electrons from travelling much faster than the ions. ) We thus have a situation where Script-Small-L /L << 1, d/ Script-Small-L << 1, {lambda}/L <<1, and {lambda}/d >> 1, where L is the characteristic dimension of the probe {lambda} is the mean free path and d the Debye length. Because of the last condition, i. e, d << {lambda}, the space charge region is contained wholly in a ''free-falling'' zone in the immediate neighbourhood of the probe. Since, also, (d/ Script-Small-L ) << 1, the region outside of the ''free-falling'' zone is in a state of ''quasi-neutrality'', i.e. the number densities of electrons and ions are approximately equal. In this latter region, the mechanisms of diffusion and recombination are both important. The two regions must of course be matched at their connecting boundaries. Furthermore, the external boundary of the ''quasi-neutrality'' region must be matched to the discharge field. Using the approximations of the classical boundary layer theory, analytic solutions are obtained in

  13. Project report: Experimental planning and verification of working fluids (WP 5)

    DEFF Research Database (Denmark)

    Babi, Deenesh Kavi

    working fluid candidates a database is required that can be simultaneously searched in order to differentiate and determine whether the generated candidates are existing or novel. Also, the next step upon selection of the candidates is performing experiments in order to test and verify the generated...... working fluids. If performed properly, the experimental step is solely verification. Experiments can either be performed virtually (in order to further reduce the number of required experiments) and/or physically. Therefore the objective of this work was the development of a database of existing working......Computer-aided molecular design (CAMD) helps in the reduction of experiments for the selection/design of optimal working fluids. In reducing the number of experiments, solutions obtain by trial and error is replaced by solutions that are based on mixture-process properties. In generating optimal...

  14. Gas inflow in oil base fluids; Influxo de gas em fluidos a base de oleo

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro, Welmar [PETROBRAS, Rio de Janeiro (Brazil). Dept. de Perfuracao. Div. de Fluidos de Perfuracao; Boas, Mario Barbosa V [PETROBRAS, Rio de Janeiro (Brazil). Centro de Pesquisas. Div. de Explotacao

    1990-12-31

    One of the major problems related to the use of oil base fluids is the dissolution of the natural gas in the fluid. This paper attempts initially at making a bibliographical review of all that was written on the subject of drilling fluids up to now. It also mentions some theoretical aspects regarding the process of gas dissolution in diesel oils, in order to produce an understanding of how the dissolution mechanism is processed. For a same increase in measured volume on the surface, the amount of gas incorporated into the fluid is significantly larger if the gas is dissolved in the oil phase than if it is emulsified in the fluid, as occurs when the fluid is water base. A rig team used to working with water-base fluids may be surprised with the fact that an increase of 20 bbl of fluid on the surface of a 5000 m well can mean the incorporation of about 1800 m{sup 3} of gas, if the fluid is oil-base and all the gas is in solution instead of the incorporation of 900 m{sup 3} if the fluid is water base. This paper has the goal of warning drilling engineers and technicians about this problem, as well as presenting charts and equations that allow for a more realistic evaluation of the amount of gas incorporated into oil fluids. (author) 16 refs., 7 figs., 2 tabs.

  15. Reviews on Physically Based Controllable Fluid Animation

    Directory of Open Access Journals (Sweden)

    Pizzanu Kanongchaiyos

    2010-04-01

    Full Text Available In computer graphics animation, animation tools are required for fluid-like motions which are controllable by users or animator, since applying the techniques to commercial animations such as advertisement and film. Many developments have been proposed to model controllable fluid simulation with the need in realistic motion, robustness, adaptation, and support more required control model. Physically based models for different states of substances have been applied in general in order to permit animators to almost effortlessly create interesting, realistic, and sensible animation of natural phenomena such as water flow, smoke spread, etc. In this paper, we introduce the methods for simulation based on physical model and the techniques for control the flow of fluid, especially focus on particle based method. We then discuss the existing control methods within three performances; control ability, realism, and computation time. Finally, we give a brief of the current and trend of the research areas.

  16. Thermo-economic analysis and selection of working fluid for solar organic Rankine cycle

    International Nuclear Information System (INIS)

    Desai, Nishith B.; Bandyopadhyay, Santanu

    2016-01-01

    Highlights: • Concentrating solar power plant with organic Rankine cycle. • Thermo-economic analysis of solar organic Rankine cycle. • Performance evaluation for different working fluids. • Comparison diagram to select appropriate working fluid. - Graphical Abstract: Display Omitted - Abstract: Organic Rankine cycle (ORC), powered by line-focusing concentrating solar collectors (parabolic trough collector and linear Fresnel reflector), is a promising option for modular scale. ORC based power block, with dry working fluids, offers higher design and part-load efficiencies compared to steam Rankine cycle (SRC) in small-medium scale, with temperature sources up to 400 °C. However, the cost of ORC power block is higher compared to the SRC power block. Similarly, parabolic trough collector (PTC) system has higher optical efficiency and higher cost compared to linear Fresnel reflector (LFR) system. The thermodynamic efficiencies and power block costs also vary with working fluids of the Rankine cycle. In this paper, thermo-economic comparisons of organic Rankine and steam Rankine cycles powered by line-focusing concentrating solar collectors are reported. A simple selection methodology, based on thermo-economic analysis, and a comparison diagram for working fluids of power generating cycles are also proposed. Concentrating solar power plants with any collector technology and any power generating cycle can be compared using the proposed methodology.

  17. Dependence of cycle optimal configuration for closed gas turbines on thermodynamic properties of working fluids

    International Nuclear Information System (INIS)

    Andryushchenko, A.I.; Dubinin, A.B.; Krylov, E.E.

    1988-01-01

    The problem of choice of working fluids for NPP closed gas turbines (CGT) is discussed. Thermostable in the working temperature range, chemically inert relatively to structural materials, fire- and explosion - proof substances, radiation-resistant and having satisfactory neutron-physical characteristics are used as the working fluids. Final choice of a gas as a working fluid is exercised based on technical and economic comparison of different variants at optimum thermodynamic cycle and parameters for each gas. The character and degree of the effect of thermodynamic properties of gases on configuration of reference cycles of regenerative CGT are determined. It is established that efficiency and optimum parameters in nodal points of the reference cycle are specified by the degree of removing the compression processes from the critical point. Practical importance of the obtained results presupposes the possibility of rapid estimation of the efficiency of using a gas without multiparametric optimization

  18. Introduction to supercritical fluids a spreadsheet-based approach

    CERN Document Server

    Smith, Richard; Peters, Cor

    2013-01-01

    This text provides an introduction to supercritical fluids with easy-to-use Excel spreadsheets suitable for both specialized-discipline (chemistry or chemical engineering student) and mixed-discipline (engineering/economic student) classes. Each chapter contains worked examples, tip boxes and end-of-the-chapter problems and projects. Part I covers web-based chemical information resources, applications and simplified theory presented in a way that allows students of all disciplines to delve into the properties of supercritical fluids and to design energy, extraction and materials formation systems for real-world processes that use supercritical water or supercritical carbon dioxide. Part II takes a practical approach and addresses the thermodynamic framework, equations of state, fluid phase equilibria, heat and mass transfer, chemical equilibria and reaction kinetics of supercritical fluids. Spreadsheets are arranged as Visual Basic for Applications (VBA) functions and macros that are completely (source code) ...

  19. Potential of organic Rankine cycle technology in India: Working fluid selection and feasibility study

    International Nuclear Information System (INIS)

    Sarkar, Jahar; Bhattacharyya, Souvik

    2015-01-01

    India has great potential to employ the ORC (organic Rankine cycle) technology for conversion of low temperature waste heat and renewable energy. In this study, available waste heat and relevant renewable heat sources in India are reviewed and suitable working fluids for ORC have been selected based on operational, environmental and safety criteria. A feasibility study and comparison of selected fluids for ORC is also presented for Indian climates along with discussions on component, operation and cost related aspects. A comprehensive review on available heat sources and sinks shows that India has plenty of waste heat and renewable energy sources for electricity generation by means of ORC; however, condenser operation may be challenging due to wide ambient temperature variation. Appropriate performance comparison among selected working fluids shows that ammonia is the best fluid in terms of net power generation and compactness of turbo-machineries, whereas n-Pentane is the best fluid in terms of thermal efficiency and heat exchanger compactness. Both are recommended as working fluids for ORC installations in India. The study reveals that there is a great opportunity to employ this technology in India provided we have to overcome some challenges related to component selection, finance and maintenance. - Highlights: • Available waste heat and renewable heat energies, and sinks in India are reviewed. • Suitable working fluids are selected by operational, environmental and safety criteria. • A feasibility study and comparison of selected fluids are presented for Indian climates. • Ammonia and n-Pentane are recommended for ORC installation in India. • Challenges related to plant component, operation and cost are discussed.

  20. Miniature magnetic fluid seal working in liquid environments

    Energy Technology Data Exchange (ETDEWEB)

    Mitamura, Yoshinori, E-mail: ymitamura@par.odn.ne.jp [Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814 (Japan); Durst, Christopher A., E-mail: chris@procyrion.com [Procyrion, Inc., Houston, TX 77027 (United States)

    2017-06-01

    This study was carried out to develop a miniature magnetic fluid (MF) seal working in a liquid environment. The miniature MF seal is intended for use in a catheter blood pump. The requirements for the MF seal included a size of less than Ø4×4.5 mm, shaft diameter of 1 mm, sealing pressure of 200 mmHg, shaft speed of up to 40000 rpm, and life of one month. The miniature MF seal was composed of an NdFeB magnet (Ø4×Ø2×1) sandwiched between two pole pieces (Ø4×Ø1.1×0.5). A shield (Ø4×Ø1.2×1.5) was placed on the pole piece facing the liquid to minimize the influence of pump flow on the MF. The seal was installed on a Ø1 shaft. A seal was formed by injecting MF (Ms: 47.8 kA/m and η: 0.5 Pa·sec) into the gap between the pole pieces and the shaft. Total volume of the MF seal was 44 μL. A sealing pressure of 370 mmHg was obtained at motor speeds of 0-40,000 rpm. The seal remained perfect for 10 days in saline under the condition of a pump flow of 1.5 L/min (The test was terminated in accordance with plans). The seal remained intact after ethylene oxide sterilization during which the seal was exposed to high pressures. In conclusion, the newly developed MF seal will be useful for a catheter pump. - Highlights: • A miniature magnetic fluid seal working in a liquid environment was developed. • The seal can be installed on Ø1 mm shaft and can seal against 370 mmHg at 40000 rpm. • The magnetic fluid seal will be useful for a catheter blood pump.

  1. Touch sensitive electrorheological fluid based tactile display

    Science.gov (United States)

    Liu, Yanju; Davidson, Rob; Taylor, Paul

    2005-12-01

    A tactile display is programmable device whose controlled surface is intended to be investigated by human touch. It has a great number of potential applications in the field of virtual reality and elsewhere. In this research, a 5 × 5 tactile display array including electrorheological (ER) fluid has been developed and investigated. Force responses of the tactile display array have been measured while a probe was moved across the upper surface. The purpose of this was to simulate the action of touch performed by human finger. Experimental results show that the sensed surface information could be controlled effectively by adjusting the voltage activation pattern imposed on the tactels. The performance of the tactile display is durable and repeatable. The touch sensitivity of this ER fluid based tactile display array has also been investigated in this research. The results show that it is possible to sense the touching force normal to the display's surface by monitoring the change of current passing through the ER fluid. These encouraging results are helpful for constructing a new type of tactile display based on ER fluid which can act as both sensor and actuator at the same time.

  2. Design and development of a four-cell sorption compressor based J-T cooler using R134a as working fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, R. N. [Mechanical Engineering Department, Indian Institute of Technology Bombay, Mumbai - 400076, India and Government Engineering College Bharuch, Gujarat - 392002 (India); Bapat, S. L.; Atrey, M. D. [Mechanical Engineering Department, Indian Institute of Technology Bombay, Mumbai - 400076 (India)

    2014-01-29

    The need of a cooler with no electromagnetic interference and practically zero vibration has led to sorption compressor based Joule-Thomson (J-T) coolers. These are useful for sophisticated electronic, ground based and space borne systems. In a Sorption compressor, adsorbed gases are desorbed into a confined volume by raising temperature of the sorption bed resulting in an increase in pressure of the liberated gas. In order to have the system (compressor) functioning on a continuous basis, with almost a constant gas flow rate, multiple cells are used with the adaptation of Temperature Swing Adsorption (TSA) process. As the mass of the desorbed gas dictates the compressor throughput, a combination of sorbent material with high adsorption capacity for a chosen gas or gas mixture has to be selected for efficient operation of the compressor. Commercially available (coconut-shell base) activated carbon has been selected for the present application. The characterization study for variation of discharge pressure is used to design the Four-cell sorption compressor based cryocooler with a desired output. Apart from compressor, the system includes a) After cooler b) Return gas heat exchanger c) capillary tube as the J-T expansion device and d) Evaporator.

  3. Environmental pollution from working fluids of ORC processes; Umweltbelastung durch Arbeitsstoffe fuer organische Rankine-Prozesse

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, K.

    2006-07-01

    The contribution quantifies the negative environmental effects of the potential loss of working fluids and/or refrigerants and the positive environmental effect of power generation without working fluids. The TEWI (Total Equivalent Warming Impact)concept which is common in refrigeration and air conditioning was modified for ORc systems and was used for assessing the environmental effects of potential working fluids. (orig.)

  4. Power cycles with ammonia-water mixtures as working fluid

    Energy Technology Data Exchange (ETDEWEB)

    Thorin, Eva

    2000-05-01

    It is of great interest to improve the efficiency of power generating processes, i.e. to convert more of the energy in the heat source to power. This is favorable from an environmental point of view and can also be an economic advantage. To use an ammonia-water mixture instead of water as working fluid is a possible way to improve the efficiency of steam turbine processes. This thesis includes studies of power cycles with ammonia-water mixtures as working fluid utilizing different kinds of heat sources for power and heat generation. The thermophysical properties of the mixture are also studied. They play an important role in the calculations of the process performance and for the design of its components, such as heat exchangers. The studies concern thermodynamic simulations of processes in applications suitable for Swedish conditions. Available correlations for the thermophysical properties are compared and their influence on simulations and heat exchanger area predictions is investigated. Measurements of ammonia-water mixture viscosities using a vibrating wire viscometer are also described. The studies performed show that power cycles with ammonia-water mixtures as the working fluid are well suited for utilization of waste heat from industry and from gas engines. The ammonia-water power cycles can give up to 32 % more power in the industrial waste heat application and up to 54 % more power in the gas engine bottoming cycle application compared to a conventional Rankine steam cycle. However, ammonia-water power cycles in small direct-fired biomass-fueled cogeneration plants do not show better performance than a conventional Rankine steam cycle. When different correlations for the thermodynamic properties are used in simulations of a simple ammonia-water power cycle the difference in efficiency is not larger than 4 %, corresponding to about 1.3 percentage points. The differences in saturation properties between the correlations are, however, considerable at high

  5. Working Fluid Stability in Large-Scale Organic Rankine Cycle-Units Using Siloxanes—Long-Term Experiences and Fluid Recycling

    Directory of Open Access Journals (Sweden)

    Tobias G. Erhart

    2016-05-01

    Full Text Available The results in this work show the influence of long-term operation on the decomposition of working fluids in eight different organic rankine cycle (ORC power plants (both heat-led and electricity-led in a range of 900 kW el to 2 MW el . All case study plants are using octamethyltrisiloxane (MDM as a working fluid; the facilities are between six to 12 years old. Detailed analyses, including the fluid distribution throughout the cycle, are conducted on one system. All presented fluid samples are analyzed via head space gas chromatography mass spectrometry (HS-GC-MS. Besides the siloxane composition, the influence of contaminants, such as mineral oil-based lubricants (and their components, is examined. In most cases, the original working fluid degrades to fractions of siloxanes with a lower boiling point (low boilers and fractions with a higher boiling point (high boilers. As a consequence of the analyses, a new fluid recycling and management system was designed and tested in one case study plant (Case Study #8. Pre-post comparisons of fluid samples prove the effectiveness of the applied methods. The results show that the recovery of used working fluid offers an alternative to the purchase of fresh fluid, since operating costs can be significantly reduced. For large facilities, the prices for new fluid range from € 15 per liter (in 2006 to € 22 per liter (in 2013, which is a large reinvestment, especially in light of filling volumes of 4000 liters to 7000 liters per unit. Using the aforementioned method, a price of € 8 per liter of recovered MDM can be achieved.

  6. Making Work-Based Learning Work

    Science.gov (United States)

    Cahill, Charlotte

    2016-01-01

    Americans seeking employment often face a conundrum: relevant work experience is a prerequisite for many jobs, but it is difficult to gain the required experience without being in the workplace. Work-based learning--activities that occur in workplaces through which youth and adults gain the knowledge, skills, and experience needed for entry or…

  7. Variable flexure-based fluid filter

    Science.gov (United States)

    Brown, Steve B.; Colston, Jr., Billy W.; Marshall, Graham; Wolcott, Duane

    2007-03-13

    An apparatus and method for filtering particles from a fluid comprises a fluid inlet, a fluid outlet, a variable size passage between the fluid inlet and the fluid outlet, and means for adjusting the size of the variable size passage for filtering the particles from the fluid. An inlet fluid flow stream is introduced to a fixture with a variable size passage. The size of the variable size passage is set so that the fluid passes through the variable size passage but the particles do not pass through the variable size passage.

  8. Metal working fluid exposure and diseases in Switzerland.

    Science.gov (United States)

    Koller, Michael F; Pletscher, Claudia; Scholz, Stefan M; Schneuwly, Philippe

    2016-07-01

    Exposure to metal working fluids (MWF) is common in machining processes worldwide and may lead to diseases of the skin and the respiratory tract. The aim of the study was to investigate exposure and diseases due to MWF in Switzerland between 2004 and 2013. We performed descriptive statistics including determination of median and 90th percentile values of MWF concentrations listed in a database of Suva. Moreover, we clustered MWF-induced occupational diseases listed in a database from the Swiss Central Office for Statistics in Accident Insurance, and performed linear regression over time to investigate temporal course of the illnesses. The 90th percentile for MWF air concentration was 8.1 mg (aerosol + vapor)/m 3 and 0.9 mg aerosol/m 3 (inhalable fraction). One thousand two hundred and eighty skin diseases and 96 respiratory diseases were observed. This is the first investigation describing exposure to and diseases due to MWF in Switzerland over a timeframe of 10 years. In general, working conditions in the companies of this investigation were acceptable. Most measured MWF concentrations were below both the Swiss and most international occupational exposure limits of 2014. The percentage of workers declared unfit for work was 17% compared to the average of other occupational diseases (12%).

  9. Accurate fluid force measurement based on control surface integration

    Science.gov (United States)

    Lentink, David

    2018-01-01

    Nonintrusive 3D fluid force measurements are still challenging to conduct accurately for freely moving animals, vehicles, and deforming objects. Two techniques, 3D particle image velocimetry (PIV) and a new technique, the aerodynamic force platform (AFP), address this. Both rely on the control volume integral for momentum; whereas PIV requires numerical integration of flow fields, the AFP performs the integration mechanically based on rigid walls that form the control surface. The accuracy of both PIV and AFP measurements based on the control surface integration is thought to hinge on determining the unsteady body force associated with the acceleration of the volume of displaced fluid. Here, I introduce a set of non-dimensional error ratios to show which fluid and body parameters make the error negligible. The unsteady body force is insignificant in all conditions where the average density of the body is much greater than the density of the fluid, e.g., in gas. Whenever a strongly deforming body experiences significant buoyancy and acceleration, the error is significant. Remarkably, this error can be entirely corrected for with an exact factor provided that the body has a sufficiently homogenous density or acceleration distribution, which is common in liquids. The correction factor for omitting the unsteady body force, {{{ {ρ f}} {1 - {ρ f} ( {{ρ b}+{ρ f}} )}.{( {{{{ρ }}b}+{ρ f}} )}}} , depends only on the fluid, {ρ f}, and body, {{ρ }}b, density. Whereas these straightforward solutions work even at the liquid-gas interface in a significant number of cases, they do not work for generalized bodies undergoing buoyancy in combination with appreciable body density inhomogeneity, volume change (PIV), or volume rate-of-change (PIV and AFP). In these less common cases, the 3D body shape needs to be measured and resolved in time and space to estimate the unsteady body force. The analysis shows that accounting for the unsteady body force is straightforward to non

  10. A graphical criterion for working fluid selection and thermodynamic system comparison in waste heat recovery

    International Nuclear Information System (INIS)

    Xi, Huan; Li, Ming-Jia; He, Ya-Ling; Tao, Wen-Quan

    2015-01-01

    In the present study, we proposed a graphical criterion called CE diagram by achieving the Pareto optimal solutions of the annual cash flow and exergy efficiency. This new graphical criterion enables both working fluid selection and thermodynamic system comparison for waste heat recovery. It's better than the existing criterion based on single objective optimization because it is graphical and intuitionistic in the form of diagram. The features of CE diagram were illustrated by studying 5 examples with different heat-source temperatures (ranging between 100 °C to 260 °C), 26 chlorine-free working fluids and two typical ORC systems including basic organic Rankine cycle(BORC) and recuperative organic Rankine cycle (RORC). It is found that the proposed graphical criterion is feasible and can be applied to any closed loop waste heat recovery thermodynamic systems and working fluids. - Highlights: • A graphical method for ORC system comparison/working fluid selection was proposed. • Multi-objectives genetic algorithm (MOGA) was applied for optimizing ORC systems. • Application cases were performed to demonstrate the usage of the proposed method.

  11. Temperature dependence of photonic crystals based on thermoresponsive magnetic fluids

    International Nuclear Information System (INIS)

    Pu Shengli; Bai Xuekun; Wang Lunwei

    2011-01-01

    The influence mechanisms of temperature on the band gap properties of the magnetic fluids based photonic crystals are elaborated. A method has been developed to obtain the temperature-dependent structure information (A sol /A) from the existing experimental data and then two critical parameters, i.e. the structure ratio (d/a) and the refractive index contrast (Δn) of the magnetic fluids photonic crystals are deduced for band diagram calculations. The temperature-dependent band gaps are gained for z-even and z-odd modes. Band diagram calculations display that the mid frequencies and positions of the existing forbidden bands are not very sensitive to the temperature, while the number of the forbidden bands at certain strengths of magnetic field may change with the temperature variation. The results presented in this work give a guideline for designing the potential photonic devices based on the temperature characteristics of the magnetic fluids based photonic crystals and are helpful for improving their quality. - Highlights: → Mechanisms of temperature dependence of magnetic fluids based photonic crystals are elaborated. → Properties of existing forbidden bands have relatively fine temperature stability. → Disappearance of existing forbidden band is found for some magnetic fields. → Emergence of new forbidden band with temperature is found for some magnetic fields.

  12. Influence of working fluids on startup mechanism and thermal performance of a closed loop pulsating heat pipe

    International Nuclear Information System (INIS)

    Patel, Vipul M.; Gaurav; Mehta, Hemantkumar B.

    2017-01-01

    Highlights: • Startup mechanism and thermal performance of a CLPHP is reported. • Influence of pure fluids, water-based binary fluids and surfactant solutions are investigated. • Startup heat flux is observed lower for acetone and higher for water compared to all other working fluids. • Thermal resistance is observed to decrease with increase in heat input irrespective of working fluids. • CLPHP is observed to perform better with acetone, water-acetone, water-45 PPM and water-60 PPM surfactant solutions. - Abstract: Development of efficient cooling system is a tricky and challenging task in the field of electronics. Pulsating heat pipe has a great prospect in the upcoming days for an effective cooling solution due to its excellent heat transfer characteristics. Experimental investigations are reported on a Closed Loop Pulsating Heat Pipe (CLPHP). The influence of working fluids on startup mechanism and thermal performance of a CLPHP are carried out on 2 mm, nine turn copper capillary. Total eleven (11) working fluids are prepared and investigated. Deionized (DI) Water (H_2O), ethanol (C_2H_6O), methanol (CH_3OH) and acetone (C_3H_6O) are used as pure fluids. The water-based mixture (1:1) of acetone, methanol and ethanol are used as binary fluids. Sodium Dodecyl Sulphate (SDS, NaC_1_2H_2_5SO_4) is used as a surfactant to prepare the water-based surfactant solutions of 30 PPM, 45 PPM, 60 PPM and 100 PPM. The filling ratio is kept as 50%. The vertical bottom heating position of a CLPHP is considered. Heat input is varied in the range of 10–110 W. Significant influence is observed for water-based binary fluids and surfactant solutions on startup mechanism and thermal performance of a CLPHP compared to DI water used as the pure working fluid.

  13. Thermo-economic evaluation of ORCs for various working fluids

    International Nuclear Information System (INIS)

    Garg, Pardeep; Orosz, Matthew S.; Kumar, Pramod

    2016-01-01

    An inclusive component-level technical and economic assessment procedure for the general design and operating strategy of Organic Rankine Cycles (ORC) for use across major application categories (waste heat recovery, solar thermal, geothermal) and sub-MW scales can be an important tool for leveraging the cost-effective deployment of low and medium temperature power cycles. Previous analyses and design approaches tended to focus on thermodynamic efficiency rather than financial performance. To bridge this gap, a general thermo-economic optimization of sub 500 kWe ORCs is developed using a 7-dimensional design space with minimum investment cost per unit of nameplate electricity production as an objective function. Parameters used include working fluid, heat source temperature, pinch in condenser, boiler (HEX) and regenerator, expander inlet pressure and air cooled condenser area. Optimized power block configurations are presented for the application of ORCs with waste or “free” heat sources and solar heat input for power scales of 5, 50 and 500 kWe to facilitate rapid selection of design parameters across a wide range of thermal regimes. While R152a yields the lowest cost ORCs in the case of the former, isopentane is found to be more cost effective in the latter case for heat source temperatures between 125 and 275 °C.

  14. Improving fluid intelligence with training on working memory.

    Science.gov (United States)

    Jaeggi, Susanne M; Buschkuehl, Martin; Jonides, John; Perrig, Walter J

    2008-05-13

    Fluid intelligence (Gf) refers to the ability to reason and to solve new problems independently of previously acquired knowledge. Gf is critical for a wide variety of cognitive tasks, and it is considered one of the most important factors in learning. Moreover, Gf is closely related to professional and educational success, especially in complex and demanding environments. Although performance on tests of Gf can be improved through direct practice on the tests themselves, there is no evidence that training on any other regimen yields increased Gf in adults. Furthermore, there is a long history of research into cognitive training showing that, although performance on trained tasks can increase dramatically, transfer of this learning to other tasks remains poor. Here, we present evidence for transfer from training on a demanding working memory task to measures of Gf. This transfer results even though the trained task is entirely different from the intelligence test itself. Furthermore, we demonstrate that the extent of gain in intelligence critically depends on the amount of training: the more training, the more improvement in Gf. That is, the training effect is dosage-dependent. Thus, in contrast to many previous studies, we conclude that it is possible to improve Gf without practicing the testing tasks themselves, opening a wide range of applications.

  15. Self-rewetting carbon nanofluid as working fluid for space and terrestrial heat pipes

    Science.gov (United States)

    Di Paola, R.; Savino, R.; Mirabile Gattia, D.; Marazzi, R.; Vittori Antisari, M.

    2011-11-01

    Thermal management is very important in modern electronic systems. Recent researches have been dedicated to the study of the heat transfer performances of binary heat transfer fluids with peculiar surface tension properties and in particular to that of "self-rewetting fluids", i.e., liquids with a surface tension increasing with temperature and concentration. Since in the course of liquid/vapor-phase change, self-rewetting fluids behavior induces a rather strong liquid inflow (caused by both temperature and concentration gradients) from the cold region (where liquid condensates) to the hot evaporator region, this fluids have been proposed and investigated as new heat transfer fluids for advanced heat transfer devices, e.g., heat pipes or heat spreaders for terrestrial and space applications (Savino et al. in Space Technol 25(1):59-61, 2009). The present work is dedicated to the study of the thermophysical properties of a new class of heat transfer fluids based on water/alcohol solutions with suspended carbon nanostructures, in particular single-wall carbon nanohorns (SWNH), synthesized by a homemade apparatus with an AC arc discharge in open air (Mirabile Gattia et al. in Nanotechnology 18:255604, 2007). SWNHs are cone-shaped nanoparticles with diameters between 1 and 5 nm and lengths in the range of 20-100 nm. SWNHs could be found in the form of quite-spherical aggregates with diameters ranging from 20 to 100 nm. The paper also discusses the results of these investigations and laboratory characterization tests of different heat pipes, including reference ordinary heat pipes and innovative pipes filled with self-rewetting fluids and self-rewetting nanofluids. The potential interest of the proposed studies stems from the large number of possible industrial applications, including space technologies and terrestrial applications, such as cooling of electronic components.

  16. Choice of optimal working fluid for binary power plants at extremely low temperature brine

    Science.gov (United States)

    Tomarov, G. V.; Shipkov, A. A.; Sorokina, E. V.

    2016-12-01

    The geothermal energy development problems based on using binary power plants utilizing lowpotential geothermal resources are considered. It is shown that one of the possible ways of increasing the efficiency of heat utilization of geothermal brine in a wide temperature range is the use of multistage power systems with series-connected binary power plants based on incremental primary energy conversion. Some practically significant results of design-analytical investigations of physicochemical properties of various organic substances and their influence on the main parameters of the flowsheet and the technical and operational characteristics of heat-mechanical and heat-exchange equipment for binary power plant operating on extremely-low temperature geothermal brine (70°C) are presented. The calculation results of geothermal brine specific flow rate, capacity (net), and other operation characteristics of binary power plants with the capacity of 2.5 MW at using various organic substances are a practical interest. It is shown that the working fluid selection significantly influences on the parameters of the flowsheet and the operational characteristics of the binary power plant, and the problem of selection of working fluid is in the search for compromise based on the priorities in the field of efficiency, safety, and ecology criteria of a binary power plant. It is proposed in the investigations on the working fluid selection of the binary plant to use the plotting method of multiaxis complex diagrams of relative parameters and characteristic of binary power plants. Some examples of plotting and analyzing these diagrams intended to choose the working fluid provided that the efficiency of geothermal brine is taken as main priority.

  17. Miniature magnetic fluid seal working in liquid environments

    Science.gov (United States)

    Mitamura, Yoshinori; Durst, Christopher A.

    2017-06-01

    This study was carried out to develop a miniature magnetic fluid (MF) seal working in a liquid environment. The miniature MF seal is intended for use in a catheter blood pump. The requirements for the MF seal included a size of less than Ø4×4.5 mm, shaft diameter of 1 mm, sealing pressure of 200 mmHg, shaft speed of up to 40000 rpm, and life of one month. The miniature MF seal was composed of an NdFeB magnet (Ø4×Ø2×1) sandwiched between two pole pieces (Ø4×Ø1.1×0.5). A shield (Ø4×Ø1.2×1.5) was placed on the pole piece facing the liquid to minimize the influence of pump flow on the MF. The seal was installed on a Ø1 shaft. A seal was formed by injecting MF (Ms: 47.8 kA/m and η: 0.5 Pa·sec) into the gap between the pole pieces and the shaft. Total volume of the MF seal was 44 μL. A sealing pressure of 370 mmHg was obtained at motor speeds of 0-40,000 rpm. The seal remained perfect for 10 days in saline under the condition of a pump flow of 1.5 L/min (The test was terminated in accordance with plans). The seal remained intact after ethylene oxide sterilization during which the seal was exposed to high pressures. In conclusion, the newly developed MF seal will be useful for a catheter pump.

  18. Finned Carbon-Carbon Heat Pipe with Potassium Working Fluid

    Science.gov (United States)

    Juhasz, Albert J.

    2010-01-01

    This elemental space radiator heat pipe is designed to operate in the 700 to 875 K temperature range. It consists of a C-C (carbon-carbon) shell made from poly-acrylonitride fibers that are woven in an angle interlock pattern and densified with pitch at high process temperature with integrally woven fins. The fins are 2.5 cm long and 1 mm thick, and provide an extended radiating surface at the colder condenser section of the heat pipe. The weave pattern features a continuous fiber bath from the inner tube surface to the outside edges of the fins to maximize the thermal conductance, and to thus minimize the temperature drop at the condenser end. The heat pipe and radiator element together are less than one-third the mass of conventional heat pipes of the same heat rejection surface area. To prevent the molten potassium working fluid from eroding the C C heat pipe wall, the shell is lined with a thin-walled, metallic tube liner (Nb-1 wt.% Zr), which is an integral part of a hermetic metal subassembly which is furnace-brazed to the inner surface of the C-C tube. The hermetic metal liner subassembly includes end caps and fill tubes fabricated from the same Nb-1Zr alloy. A combination of laser and electron beam methods is used to weld the end caps and fill tubes. A tungsten/inert gas weld seals the fill tubes after cleaning and charging the heat pipes with potassium. The external section of this liner, which was formed by a "Uniscan" rolling process, transitions to a larger wall thickness. This section, which protrudes beyond the C-C shell, constitutes the "evaporator" part of the heat pipe, while the section inside the shell constitutes the condenser of the heat pipe (see figure).

  19. Fluid, solid and fluid-structure interaction simulations on patient-based abdominal aortic aneurysm models.

    Science.gov (United States)

    Kelly, Sinead; O'Rourke, Malachy

    2012-04-01

    This article describes the use of fluid, solid and fluid-structure interaction simulations on three patient-based abdominal aortic aneurysm geometries. All simulations were carried out using OpenFOAM, which uses the finite volume method to solve both fluid and solid equations. Initially a fluid-only simulation was carried out on a single patient-based geometry and results from this simulation were compared with experimental results. There was good qualitative and quantitative agreement between the experimental and numerical results, suggesting that OpenFOAM is capable of predicting the main features of unsteady flow through a complex patient-based abdominal aortic aneurysm geometry. The intraluminal thrombus and arterial wall were then included, and solid stress and fluid-structure interaction simulations were performed on this, and two other patient-based abdominal aortic aneurysm geometries. It was found that the solid stress simulations resulted in an under-estimation of the maximum stress by up to 5.9% when compared with the fluid-structure interaction simulations. In the fluid-structure interaction simulations, flow induced pressure within the aneurysm was found to be up to 4.8% higher than the value of peak systolic pressure imposed in the solid stress simulations, which is likely to be the cause of the variation in the stress results. In comparing the results from the initial fluid-only simulation with results from the fluid-structure interaction simulation on the same patient, it was found that wall shear stress values varied by up to 35% between the two simulation methods. It was concluded that solid stress simulations are adequate to predict the maximum stress in an aneurysm wall, while fluid-structure interaction simulations should be performed if accurate prediction of the fluid wall shear stress is necessary. Therefore, the decision to perform fluid-structure interaction simulations should be based on the particular variables of interest in a given

  20. Graphene nanoplatelets as high-performance filtration control material in water-based drilling fluids

    Science.gov (United States)

    Ridha, Syahrir; Ibrahim, Arif; Shahari, Radzi; Fonna, Syarizal

    2018-05-01

    The main objective of this work is to evaluate the effectiveness of graphene nanoplatelets (GNP) as filtration control materials in water based drilling fluids. Three (3) general samples of water based drilling fluids were prepared including basic potassium chloride (KCl) drilling fluids, nanosilica (NS) drilling fluids and GNP drilling fluids. Several concentrations of NS and GNP were dispersed in controlled formulations of water based drilling fluids. Standard API filtration tests were carried out for comparison purposes as well as High Temperature High Pressure (HTHP) filtration tests at 150 °F (∼66 °C), 250 °F (∼121 °C) and 350 °F (∼177 °C) at a fixed 500 (∼3.45MPa) psi to study the filtration trend as a function of temperature. Mud cake samples from several tests were selectively chosen and analyzed under Field Emission Scanning Electron Microscope (FESEM) for its morphology. Results from this work show that nanoparticle concentrations play a factor in filtration ability of colloid materials in water based drilling fluids when studied at elevated temperature. Low temperature filtration, however, shows only small differences in volume in all the drilling fluid samples. 0.1 ppb concentrations of GNP reduced the fluid loss of 350 °F by 4.6 mL as compared to the similar concentration of NS drilling fluids.

  1. Synthetic-based fluid replacement: excellent drilling efficiency and imaging evaluation achieved with inhibitive water-based fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Ricardo; Fernandez, Jovan Andrade [PETROBRAS, Rio de Janeiro, RJ (Brazil); Anderson, Tom; Loureiro, Mario; Pereira, Alex; Shah, Fayyaz [Halliburton Baroid, Aracaju, SE (Brazil)

    2004-07-01

    The highly reactive Calumbi shale is encountered in wells drilled by PETROBRAS in the Sergipe area. Normally an invert emulsion fluid would be used. However, the ability to run high resolution imaging logs was crucial to determining the potential of the offshore Sergipe fields, and these tools work best in water-based fluids. PETROBRAS selected a new high performance water-based fluid (WBF) to drill the Poco 3-GA-73-SES well. The fluid selection was based on the results of X-ray diffraction, dispersion/erosion and linear swell meter testing of Calumbi formation samples. The new WBF incorporates a unique polymer chemistry that can provide shale inhibition very similar to that achieved with an invert emulsion fluid, without sacrificing drilling performance. The polymeric additives can effectively flocculate and encapsulate colloidal drill solids so that they can be easily removed mechanically. The polymers also help prevent hole erosion and bit balling. After the high-performance WBF was used, the following results were obtained on the Poco 3- GA-73-SES well: 805 m drilled in 65 hr (12.65 m/hr) in a single bit run; trips completed with minimal use of the pumps or back reaming, considered exceptional for a WBF while drilling the Calumbi shale; imaging logs run successfully with no delays or obstructions while tripping or logging; the average hole diameter was 8.63-in. per the caliper log for the 8 1/2-in. section; no accretion on the bit or drill string observed; no flow line plugging or shaker screen blinding. (author)

  2. Base fluid in improving heat transfer for EV car battery

    Science.gov (United States)

    Bin-Abdun, Nazih A.; Razlan, Zuradzman M.; Shahriman, A. B.; Wan, Khairunizam; Hazry, D.; Ahmed, S. Faiz; Adnan, Nazrul H.; Heng, R.; Kamarudin, H.; Zunaidi, I.

    2015-05-01

    This study examined the effects of base fluid (as coolants) channeling inside the heat exchanger in the process of the increase in thermal conductivity between EV car battery and the heat exchanger. The analysis showed that secondary cooling system by means of water has advantages in improving the heat transfer process and reducing the electric power loss on the form of thermal energy from batteries. This leads to the increase in the efficiency of the EV car battery, hence also positively reflecting the performance of the EV car. The present work, analysis is performed to assess the design and use of heat exchanger in increasing the performance efficiency of the EV car battery. This provides a preface to the use this design for nano-fluids which increase and improve from heat transfer.

  3. Self-rewetting carbon nanofluid as working fluid for space and terrestrial heat pipes

    International Nuclear Information System (INIS)

    Di Paola, R.; Savino, R.; Mirabile Gattia, D.; Marazzi, R.; Vittori Antisari, M.

    2011-01-01

    Thermal management is very important in modern electronic systems. Recent researches have been dedicated to the study of the heat transfer performances of binary heat transfer fluids with peculiar surface tension properties and in particular to that of “self-rewetting fluids”, i.e., liquids with a surface tension increasing with temperature and concentration. Since in the course of liquid/vapor-phase change, self-rewetting fluids behavior induces a rather strong liquid inflow (caused by both temperature and concentration gradients) from the cold region (where liquid condensates) to the hot evaporator region, this fluids have been proposed and investigated as new heat transfer fluids for advanced heat transfer devices, e.g., heat pipes or heat spreaders for terrestrial and space applications (Savino et al. in Space Technol 25(1):59–61, 2009). The present work is dedicated to the study of the thermophysical properties of a new class of heat transfer fluids based on water/alcohol solutions with suspended carbon nanostructures, in particular single-wall carbon nanohorns (SWNH), synthesized by a homemade apparatus with an AC arc discharge in open air (Mirabile Gattia et al. in Nanotechnology 18:255604, 2007). SWNHs are cone-shaped nanoparticles with diameters between 1 and 5 nm and lengths in the range of 20–100 nm. SWNHs could be found in the form of quite-spherical aggregates with diameters ranging from 20 to 100 nm. The paper also discusses the results of these investigations and laboratory characterization tests of different heat pipes, including reference ordinary heat pipes and innovative pipes filled with self-rewetting fluids and self-rewetting nanofluids. The potential interest of the proposed studies stems from the large number of possible industrial applications, including space technologies and terrestrial applications, such as cooling of electronic components.

  4. Model identification methodology for fluid-based inerters

    Science.gov (United States)

    Liu, Xiaofu; Jiang, Jason Zheng; Titurus, Branislav; Harrison, Andrew

    2018-06-01

    Inerter is the mechanical dual of the capacitor via the force-current analogy. It has the property that the force across the terminals is proportional to their relative acceleration. Compared with flywheel-based inerters, fluid-based forms have advantages of improved durability, inherent damping and simplicity of design. In order to improve the understanding of the physical behaviour of this fluid-based device, especially caused by the hydraulic resistance and inertial effects in the external tube, this work proposes a comprehensive model identification methodology. Firstly, a modelling procedure is established, which allows the topological arrangement of the mechanical networks to be obtained by mapping the damping, inertance and stiffness effects directly to their respective hydraulic counterparts. Secondly, an experimental sequence is followed, which separates the identification of friction, stiffness and various damping effects. Furthermore, an experimental set-up is introduced, where two pressure gauges are used to accurately measure the pressure drop across the external tube. The theoretical models with improved confidence are obtained using the proposed methodology for a helical-tube fluid inerter prototype. The sources of remaining discrepancies are further analysed.

  5. A multi-objective optimization approach for the selection of working fluids of geothermal facilities: Economic, environmental and social aspects.

    Science.gov (United States)

    Martínez-Gomez, Juan; Peña-Lamas, Javier; Martín, Mariano; Ponce-Ortega, José María

    2017-12-01

    The selection of the working fluid for Organic Rankine Cycles has traditionally been addressed from systematic heuristic methods, which perform a characterization and prior selection considering mainly one objective, thus avoiding a selection considering simultaneously the objectives related to sustainability and safety. The objective of this work is to propose a methodology for the optimal selection of the working fluid for Organic Rankine Cycles. The model is presented as a multi-objective approach, which simultaneously considers the economic, environmental and safety aspects. The economic objective function considers the profit obtained by selling the energy produced. Safety was evaluated in terms of individual risk for each of the components of the Organic Rankine Cycles and it was formulated as a function of the operating conditions and hazardous properties of each working fluid. The environmental function is based on carbon dioxide emissions, considering carbon dioxide mitigation, emission due to the use of cooling water as well emissions due material release. The methodology was applied to the case of geothermal facilities to select the optimal working fluid although it can be extended to waste heat recovery. The results show that the hydrocarbons represent better solutions, thus among a list of 24 working fluids, toluene is selected as the best fluid. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Comparative performance analysis of low-temperature Organic Rankine Cycle (ORC) using pure and zeotropic working fluids

    International Nuclear Information System (INIS)

    Aghahosseini, S.; Dincer, I.

    2013-01-01

    In this paper, a comprehensive thermodynamic analysis of the low-grade heat source Organic Rankine Cycle (ORC) is conducted and the cycle performance is analyzed and compared for different pure and zeotropic-mixture working fluids. The comparative performance evaluation of the cycle using a combined energy and exergy analysis is carried out by sensitivity assessment of the cycle certain operating parameters such as efficiency, flow rate, irreversibility, and heat input requirement at various temperatures and pressures. The environmental characteristics of the working fluids such as toxicity, flammability, ODP and GWP are studied and the cycle CO 2 emission is compared with different fuel combustion systems. R123, R245fa, R600a, R134a, R407c, and R404a are considered as the potential working fluids. Results from this analysis provide valuable insight into selection of the most suitable working fluids for power generating application at different operating conditions with a minimal environmental impact. -- Highlights: ► Combined energy and exergy analysis is conducted for Organic Rankine Cycle. ► Comparative assessment is performed for different pure and zeotropic working fluids. ► Exergy and energy efficiency, cycle irreversibility, and required external heat are analyzed. ► Toxicity, flammability, ODP and GWP of considered working fluids are studied. ► Environmental benefits of the renewable/waste heat-based ORC are investigated

  7. Theoretical study of effect of working fluid on the performance of 77–100 K adsorption cryocooler

    International Nuclear Information System (INIS)

    Luo, B.J.; Wang, Z.L.; Yan, T.; Hong, G.T.; Li, Y.L.; Liang, J.T.

    2015-01-01

    Highlights: • Investigate the effects of nitrogen, argon and oxygen on the performance of adsorption cryocooler in the range 77–100 K. • A model of adsorption compressor with a two-stage adsorption compressor is constructed and optimized with genetic algorithm. • Working fluid has larger effects on the adsorption compressor than on the cold stage. • The best selection of working fluid depends on the operating parameters. - Abstract: The aim of this study is to investigate the effects of working fluid (nitrogen, argon and oxygen) on the performance of adsorption cryocooler in the range 77–100 K. A thermodynamic model of adsorption cryocooler with two-stage compressor has been constructed. The model is based on quasi-static conditions without considering the temperature profiles and pressure drops across the compressor. It is then analyzed with an optimization toolbox to determine the optimum operating conditions to obtain the optimum performance of adsorption cryocooler. The Coefficient of Performance (COP) for each working fluid in the range 77–100 K is obtained and compared. It is found that working fluid has larger effects on adsorption compressor than on cold stage, and the optimum selection of working fluid depends on the operating parameters

  8. Study of working fluid selection of organic Rankine cycle (ORC) for engine waste heat recovery

    International Nuclear Information System (INIS)

    Wang, E.H.; Zhang, H.G.; Fan, B.Y.; Ouyang, M.G.; Zhao, Y.; Mu, Q.H.

    2011-01-01

    Organic Rankine Cycle (ORC) could be used to recover low-grade waste heat. When a vehicle is running, the engine exhaust gas states have a wide range of variance. Defining the operational conditions of the ORC that achieve the maximum utilization of waste heat is important. In this paper the performance of different working fluids operating in specific regions was analyzed using a thermodynamic model built in Matlab together with REFPROP. Nine different pure organic working fluids were selected according to their physical and chemical properties. The results were compared in the regions when net power outputs were fixed at 10 kW. Safety levels and environmental impacts were also evaluated. The outcomes indicate that R11, R141b, R113 and R123 manifest slightly higher thermodynamic performances than the others; however, R245fa and R245ca are the most environment-friendly working fluids for engine waste heat-recovery applications. The optimal control principle of ORC under the transient process is discussed based on the analytical results. -- Highlights: → R11, R141b, R113 and R123 manifest the best thermodynamic performances. → R245fa and R245ca are the most environment-friendly working fluids for the engine waste heat-recovery application. → The condensing temperature has more important effect than the evaporating pressure to the performance of ORC. → The optimal control principle of ORC under the transient process was defined according to the calculation results for the vehicle engine waste heat-recovery application. → ORC thermodynamic model was built in Matlab together with REFPROP.

  9. Sensitivity analysis of molecular design problem for the development of novel working fluids for power cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    . Multi-criteria database search and Computer Aided Molecular Design (CAMD) can be applied to generate, test and evaluate promising pure component/mixture candidate as process fluids to help optimize cycle design and performance [1]. The problem formulation for the development of novel working fluids...... a certain working fluid property parameter on the performance of the power cycle, i.e. the net power output, can facilitate the identification key properties for working fluids. In that sense a sensitivity analysis of the different parameters is suggested in this work as a systematic method to efficiently...... technology to convert such waste heat sources into usable energy. So far the low-temperature heat is not utilized efficiently for electricity generation. To optimize the heat transfer process and the power generation, the influence of the working fluid, the cycle designs and the operating conditions is vital...

  10. Improving fluid intelligence with training on working memory

    OpenAIRE

    Jaeggi, Susanne M.; Buschkuehl, Martin; Jonides, John; Perrig, Walter J.

    2008-01-01

    Fluid intelligence (Gf) refers to the ability to reason and to solve new problems independently of previously acquired knowledge. Gf is critical for a wide variety of cognitive tasks, and it is considered one of the most important factors in learning. Moreover, Gf is closely related to professional and educational success, especially in complex and demanding environments. Although performance on tests of Gf can be improved through direct practice on the tests themselves, there is no evidence ...

  11. Design and testing of high temperature micro-ORC test stand using Siloxane as working fluid

    Science.gov (United States)

    Turunen-Saaresti, Teemu; Uusitalo, Antti; Honkatukia, Juha

    2017-03-01

    Organic Rankine Cycle is a mature technology for many applications e.g. biomass power plants, waste heat recovery and geothermal power for larger power capacity. Recently more attention is paid on an ORC utilizing high temperature heat with relatively low power. One of the attractive applications of such ORCs would be utilization of waste heat of exhaust gas of combustion engines in stationary and mobile applications. In this paper, a design procedure of the ORC process is described and discussed. The analysis of the major components of the process, namely the evaporator, recuperator, and turbogenerator is done. Also preliminary experimental results of an ORC process utilizing high temperature exhaust gas heat and using siloxane MDM as a working fluid are presented and discussed. The turbine type utilized in the turbogenerator is a radial inflow turbine and the turbogenerator consists of the turbine, the electric motor and the feed pump. Based on the results, it was identified that the studied system is capable to generate electricity from the waste heat of exhaust gases and it is shown that high molecular weight and high critical temperature fluids as the working fluids can be utilized in high-temperature small-scale ORC applications. 5.1 kW of electric power was generated by the turbogenerator.

  12. Potential of organic Rankine cycle using zeotropic mixtures as working fluids for waste heat recovery

    International Nuclear Information System (INIS)

    Li, You-Rong; Du, Mei-Tang; Wu, Chun-Mei; Wu, Shuang-Ying; Liu, Chao

    2014-01-01

    The performance of the ORC (organic Rankine cycle) systems using zeotropic mixtures as working fluids for recovering waste heat of flue gas from industrial boiler is examined on the basis of thermodynamics and thermo-economics under different operating conditions. In order to explore the potential of the mixtures as the working fluids in the ORC, the effects of various mixtures with different components and composition proportions on the system performance have been analyzed. The results show that the compositions of the mixtures have an important effect on the ORC system performance, which is associated with the temperature glide during the phase change of mixtures. From the point of thermodynamics, the performance of the ORC system is not always improved by employing the mixtures as the working fluids. The merit of the mixtures is related to the restrictive conditions of the ORC, different operating conditions results in different conclusions. At a fixed pinch point temperature difference, the small mean heat transfer temperature difference in heat exchangers will lead to a larger heat transfer area and the larger total cost of the ORC system. Compared with the ORC with pure working fluids, the ORC with the mixtures presents a poor economical performance. - Highlights: • Organic Rankine cycle system with the mixture working fluids for recovering waste heat is analyzed. • The performance of the mixture-fluid ORC is related to temperature glide in phase change of mixture working fluids. • The relative merit of the mixture working fluids depends on the restrictive operation conditions of the ORC. • The ORC with mixture working fluid presents a poor economical performance compared with the pure working fluid case

  13. Performance analysis a of solar driven organic Rankine cycle using multi-component working fluids

    DEFF Research Database (Denmark)

    Baldasso, E.; Andreasen, J. G.; Modi, A.

    2015-01-01

    suitable control strategy and both the overall annual production and the average solar to electrical efficiency are estimated with an annual simulation. The results suggest that the introduction of binary working fluids enables to increase the solar system performance both in design and part-load operation....... cycle. The purpose of this paper is to optimize a low temperature organic Rankine cycle tailored for solar applications. The objective of the optimization is the maximization of the solar to electrical efficiency and the optimization parameters are the working fluid and the turbine inlet temperature...... and pressure. Both pure fluids and binary mixtures are considered as possible working fluids and thus one of the primary aims of the study is to evaluate whether the use of multi-component working fluids might lead to increased solar to electrical efficiencies. The considered configuration includes a solar...

  14. A MEMS SOI-based piezoresistive fluid flow sensor

    Science.gov (United States)

    Tian, B.; Li, H. F.; Yang, H.; Song, D. L.; Bai, X. W.; Zhao, Y. L.

    2018-02-01

    In this paper, a SOI (silicon-on-insulator)-based piezoresistive fluid flow sensor is presented; the presented flow sensor mainly consists of a nylon sensing head, stainless steel cantilever beam, SOI sensor chip, printed circuit board, half-cylinder gasket, and stainless steel shell. The working principle of the sensor and some detailed contrastive analysis about the sensor structure were introduced since the nylon sensing head and stainless steel cantilever beam have distinct influence on the sensor performance; the structure of nylon sensing head and stainless steel cantilever beam is also discussed. The SOI sensor chip was fabricated using micro-electromechanical systems technologies, such as reactive ion etching and low pressure chemical vapor deposition. The designed fluid sensor was packaged and tested; a calibration installation system was purposely designed for the sensor experiment. The testing results indicated that the output voltage of the sensor is proportional to the square of the fluid flow velocity, which is coincident with the theoretical derivation. The tested sensitivity of the sensor is 3.91 × 10-4 V ms2/kg.

  15. Microscope-Based Fluid Physics Experiments in the Fluids and Combustion Facility on ISS

    Science.gov (United States)

    Doherty, Michael P.; Motil, Susan M.; Snead, John H.; Malarik, Diane C.

    2000-01-01

    At the NASA Glenn Research Center, the Microgravity Science Program is planning to conduct a large number of experiments on the International Space Station in both the Fluid Physics and Combustion Science disciplines, and is developing flight experiment hardware for use within the International Space Station's Fluids and Combustion Facility. Four fluids physics experiments that require an optical microscope will be sequentially conducted within a subrack payload to the Fluids Integrated Rack of the Fluids and Combustion Facility called the Light Microscopy Module, which will provide the containment, changeout, and diagnostic capabilities to perform the experiments. The Light Microscopy Module is planned as a fully remotely controllable on-orbit microscope facility, allowing flexible scheduling and control of experiments within International Space Station resources. This paper will focus on the four microscope-based experiments, specifically, their objectives and the sample cell and instrument hardware to accommodate their requirements.

  16. Working memory capacity and fluid abilities: The more difficult the item, the more more is better

    OpenAIRE

    Daniel R Little; Stephan eLewandowsky; Stephan eLewandowsky; Stewart eCraig

    2014-01-01

    The relationship between fluid intelligence and working memory is of fundamental importance to understanding how capacity-limited structures such as working memory interact with inference abilities to determine intelligent behaviour. Recent evidence has suggested that the relationship between a fluid abilities test, Raven's Progressive Matrices, and working memory capacity (WMC) may be invariant across difficulty levels of the Raven's items. We show that this invariance can only be observed i...

  17. Boiling of multicomponent working fluids used in refrigeration and cryogenic systems

    Science.gov (United States)

    Mogorychny, V. I.; Dolzhikov, A. S.

    2017-11-01

    Working fluids based on mixtures are widely used in cryogenic and refrigeration engineering. One of the main elements of low-temperature units is a recuperative heat exchanger where the return flow cools the direct (cold regeneration is carrying out) resulting in continuous boiling and condensation of the multicomponent working fluid in the channels. The temperature difference between the inlet and outlet of the heat exchanger can be more than 100K, which leads to a strong change in thermophysical properties along its length. In addition, the fraction of the liquid and vapor phases in the flow varies very much, which affects the observed flow regimes in the heat exchanger channels. At the moment there are not so many experimental data and analytical correlations that would allow to estimate the heat transfer coefficient during the flow of a two-phase mixture flow at low temperatures. The work is devoted to the study of the boiling process of multicomponent working fluids used in refrigeration and cryogenic engineering. The description of the method of determination of heat transfer coefficient during boiling of mixtures in horizontal heated channel is given as well as the design of the experimental stand allowing to make such measurements. This stand is designed on the basis of a refrigeration unit operating on the Joule-Thomson throttle cycle and makes it possible to measure the heat transfer coefficient with a good accuracy. Also, the calculated values of the heat transfer coefficient, obtained with the use of various correlations, are compared with the existing experimental data. Knowing of the heat transfer coefficient will be very useful in the design of heat exchangers for low-temperature units operating on a mixture refrigerant.

  18. Second law analysis of novel working fluid pairs for waste heat recovery by the Kalina cycle

    International Nuclear Information System (INIS)

    Eller, Tim; Heberle, Florian; Brüggemann, Dieter

    2017-01-01

    The organic Rankine cycle (ORC) and the Kalina cycle (KC) are potential thermodynamic concepts for decentralized power generation from industrial waste heat at a temperature level below 500 °C. The aim of this work is to investigate in detail novel zeotropic mixtures as working fluid for the KC and compare to sub- and supercritical ORC based on second law efficiency. Heat source temperature is varied between 200 °C and 400 °C. The results show that second law efficiency of KC can be increased by applying alcohol/alcohol mixtures as working fluid instead of ammonia/water mixtures; especially for heat source temperatures above 250 °C. Efficiency increase is in the range of 16% and 75%. Despite this efficiency improvements, ORC with zeotropic mixtures in sub- and supercritical operation mode proves to be superior to KC in the examined temperature range. Second law efficiency is up to 13% higher than for KC. A maximum second law efficiency of 59.2% is obtained for supercritical ORC with benzene/toluene 36/64 at 400 °C heat source temperature. The higher level of efficiency and the lower complexity of ORC in comparison to KC indicate that ORC with zeotropic mixtures offers the greater potential for waste heat recovery. - Highlights: • Kalina Cycle with novel alcohol mixtures as working fluid is investigated. • Results are compared to ammonia/water-Kalina Cycle and ORC. • Second law efficiency of Kalina Cycle can be increased by novel alcohol mixtures. • Efficiency increase is in the range of 16% and 75%. • ORC with zeotropic mixtures proves to be superior to Kalina Cycle.

  19. Prospects of the use of nanofluids as working fluids for organic Rankine cycle power systems

    DEFF Research Database (Denmark)

    Mondejar, Maria E.; Andreasen, Jesper G.; Regidor, Maria

    2017-01-01

    The search of novel working fluids for organic Rankine cycle power systems is driven by the recent regulations imposing additional phase-out schedules for substances with adverse environmental characteristics. Recently, nanofluids (i.e. colloidal suspensions of nanoparticles in fluids) have been...... suggested as potential working fluids for organic Rankine cycle power systems due to their enhanced thermal properties, potentially giving advantages with respect to the design of the components and the cycle performance. Nevertheless, a number of challenges concerning the use of nanofluids must...... the prospects of using nanofluids as working fluids for organic Rankine cycle power systems. As a preliminary study, nanofluids consisting of a homogenous and stable mixture of different nanoparticles types and a selected organic fluid are simulated on a case study organic Rankine cycle unit for waste heat...

  20. VIBRATION ANALYSIS OF TURBINE BASED ON FLUID-STRUCTURE COUPLING

    Institute of Scientific and Technical Information of China (English)

    LIU Demin; LIU Xiaobing

    2008-01-01

    The vibration of a Francis turbine is analyzed with the additional quality matrix method based on fluid-structure coupling (FSC). Firstly, the vibration frequency and mode of blade and runner in air and water are calculated. Secondly, the influences to runner frequency domain by large flow, small flow and design flow working conditions are compared. Finally the influences to runner modes by centrifugal forces under three rotating speeds of 400 r/min, 500 r/min and 600 r/min are compared. The centrifugal force and small flow working condition have greatly influence on the vibration of small runner. With the increase of centrifugal force, the vibration frequency of the runner is sharply increased. Some order frequencies are even close to the runner natural frequency in the air. Because the low frequency vibration will severely damage the stability of the turbine, low frequency vibration of units should be avoided as soon as possible.

  1. Properties of forced convection experimental with silicon carbide based nano-fluids

    Science.gov (United States)

    Soanker, Abhinay

    With the advent of nanotechnology, many fields of Engineering and Science took a leap to the next level of advancements. The broad scope of nanotechnology initiated many studies of heat transfer and thermal engineering. Nano-fluids are one such technology and can be thought of as engineered colloidal fluids with nano-sized colloidal particles. There are different types of nano-fluids based on the colloidal particle and base fluids. Nano-fluids can primarily be categorized into metallic, ceramics, oxide, magnetic and carbon based. The present work is a part of investigation of the thermal and rheological properties of ceramic based nano-fluids. alpha-Silicon Carbide based nano-fluid with Ethylene Glycol and water mixture 50-50% volume concentration was used as the base fluid here. This work is divided into three parts; Theoretical modelling of effective thermal conductivity (ETC) of colloidal fluids, study of Thermal and Rheological properties of alpha-SiC nano-fluids, and determining the Heat Transfer properties of alpha-SiC nano-fluids. In the first part of this work, a theoretical model for effective thermal conductivity (ETC) of static based colloidal fluids was formulated based on the particle size, shape (spherical), thermal conductivity of base fluid and that of the colloidal particle, along with the particle distribution pattern in the fluid. A MATLAB program is generated to calculate the details of this model. The model is specifically derived for least and maximum ETC enhancement possible and thereby the lower and upper bounds was determined. In addition, ETC is also calculated for uniform colloidal distribution pattern. Effect of volume concentration on ETC was studied. No effect of particle size was observed for particle sizes below a certain value. Results of this model were compared with Wiener bounds and Hashin- Shtrikman bounds. The second part of this work is a study of thermal and rheological properties of alpha-Silicon Carbide based nano-fluids

  2. Working fluid selection for an Organic Rankine Cycle utilizing high and low temperature energy of an LNG engine

    International Nuclear Information System (INIS)

    He, Sinian; Chang, Huawei; Zhang, Xiaoqing; Shu, Shuiming; Duan, Chen

    2015-01-01

    This study proposed a combined Organic Rankine Cycle (ORC) system utilizing exhaust waste as its heat source and liquid natural gas (LNG) as its heat sink to provide alternative power for an LNG-fired vehicle. This system, consisting of a regenerator and a dual heat source composite heat exchanger, was designed to efficiently recover the engine waste heat (EWH) and to guarantee vaporizing LNG steadily. Five potential applicable organic working fluids are analyzed: C4F10, CF3I, R236EA, R236FA and RC318. Each fluid was analyzed at various evaporation temperatures and condensation temperatures using a thermodynamic model, and a self-made MATLAB program based on the physical properties on REFPROP data was applied to run the simulation. Analytical results showed that fluid R236FA has the highest thermal efficiency η_t_h of 21.6%, and that of the others are also around 21%. Based on a twelve-cylinder four stroke stationary natural gas engine, the simulated calculations show that the selected five working fluids can improve the fuel economy by more than 14.7% compared to that without ORC. - Highlights: • We design an ORC utilizing LNG cold energy and engine waste heat. • Five working fluids are examined at various working conditions. • The maximum thermal efficient of our proposed cycle can reach 20.3%–21.6%. • This system can decrease the brake specific fuel consumption by more than 14.7%.

  3. Scanning Probe Microscope-Based Fluid Dispensing

    NARCIS (Netherlands)

    Ghatkesar, M.K.; Perez Garza, H.H.; Heuck, F.; Staufer, U.

    2014-01-01

    Advances in micro and nano fabrication technologies have enabled fabrication of smaller and more sensitive devices for applications not only in solid-state physics but also in medicine and biology. The demand for devices that can precisely transport material, specifically fluids are continuously

  4. Numerical study of shear thickening fluid with discrete particles embedded in a base fluid

    Directory of Open Access Journals (Sweden)

    W Zhu

    2016-09-01

    Full Text Available The Shear Thickening Fluid (STF is a dilatant material, which displays non-Newtonian characteristics in its unique ability to transit from a low viscosity fluid to a high viscosity fluid. The research performed investigates the STF behavior by modeling and simulation of the interaction between the base flow and embedded rigid particles when subjected to shear stress. The model considered the Lagrangian description of the rigid particles and the Eulerian description of fluid flow. The numerical analysis investigated key parameters such as applied flow acceleration, particle distribution and arrangement, volume concentration of particles, particle size, shape and their behavior in a Newtonian and non-Newtonian fluid base. The fluid-particle interaction model showed that the arrangement, size, shape and volume concentration of the particles had a significant effect on the behavior of the STF. Although non-conclusive, the addition of particles in non-Newtonian fluids showed a promising trend of improved shear thickening effects at high shear strain rates.

  5. High-potential Working Fluids for Next Generation Binary Cycle Geothermal Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Zia, Jalal [GE Global Research; Sevincer, Edip; Chen, Huijuan; Hardy, Ajilli; Wickersham, Paul; Kalra, Chiranjeev; Laursen, Anna Lis; Vandeputte, Thomas

    2013-06-29

    hours of exposure?only 3% of the initial charge degraded into by products. The main degradation products being an isomer and a dimer. 3. In a comparative experiment between R245fa and the new fluid under subcritical conditions, it was found that the new fluid operated at 1 bar lower than R245fa for the same power output, which was also predicted in the Aspen HSYSY model. As a drop-in replacement fluid for R245fa, this new fluid was found to be at least as good as R245fa in terms of performance and stability. Further optimization of the subcritical cycle may lead to a significant improvement in performance for the new fluid. 4. For supercritical conditions, the experiment found a good match between the measured and model predicted state point property data and duties from the energy balance. The largest percent differences occurred with densities and evaporator duty (see Figure 78). It is therefore reasonable to conclude that the state point model was experimentally validated with a realistic ORC system. 5. The team also undertook a preliminary turbo-expander design study for a supercritical ORC cycle with the new working fluid. Variants of radial and axial turbo expander geometries went through preliminary design and rough costing. It was found that at 15MWe or higher power rating, a multi-stage axial turbine is most suitable providing the best performance and cost. However, at lower power ratings in the 5MWe range, the expander technology to be chosen depends on the application of the power block. For EGS power blocks, it is most optimal to use multi-stage axial machines. In conclusion, the predictions of the LCOE model that showed a supercritical cycle based on the new fluid to be most advantageous for geothermal power production at a resource temperature of ~ 200C have been experimentally validated. It was found that the cycle based on the new fluid is lower in LCOE and higher in net power output (for the same boundary conditions). The project, therefore has found a

  6. The development of working memory capacity and fluid intelligence in children

    OpenAIRE

    Engel de Abreu, Pascale; Gathercole, S; Conway, A

    2010-01-01

    A longitudinal study was conducted to investigate the relationship between working memory capacity and fluid intelligence and how this relationship develops in early childhood. The major aim was to determine which aspect of the working memory system – short-term storage or executive attention – drives the relationship with fluid intelligence. A sample of 119 children was followed from kindergarten to second grade and completed multiple assessments of short-term memory, wor...

  7. Agarwood Waste as A New Fluid Loss Control Agent in Water-based Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Azlinda Azizi

    2013-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Agarwood has been used widely in various ways, including traditional medicine and art. The usage of agarwood has grown broader in modern times include in therapeutic medicines and perfumery. In this paper the agarwood waste has been explored to be used as a fluid loss control agent to control fluid loss without affecting the drilling fluid rheological properties which are density, pH, viscosity, yield point and gel strength. Agarwood waste was used as an additive in the drilling fluid system due to its unique characteristic. Rheological and filtration measurements were performed on the formulated water-based drilling fluid. Formulations of a base solution of fresh water, sodium hydroxide, bentonite, barite, and xanthan gum were presented. The performance of the agarwood waste as the fluid loss control agent was compared with based fluid formulation and water-based drilling fluid with treating with conventional fluid loss control agent (starch. The filtrate volume of drilling fluid with agarwood waste was about 13 ml while for drilling fluid with conventional fluid loss control agent, starch gave 12 ml of filtrate volume after undergoing filtration test by using LPLT filter press. The performance of drilling fluid with agarwood was efficient as drilling fluid with starch. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso

  8. A study of organic working fluids of an organic Rankine cycle for solar concentrating power plant

    International Nuclear Information System (INIS)

    Saifaoui, D.; Elmaanaoui, Y.; Faik, A.

    2014-01-01

    This work is a comparative study between four different configurations of an organic Rankine cycle (ORC) in order to find the configuration that gives the best performances. This study also made a comparison between seven organic fluids used as working fluids in the four ORC configurations. These fluids are all hydrocarbons. Then we made a parametric analysis of the results obtained in this first part. In a second part, we developed the binary mixtures of the seven pure hydrocarbons with the NIST software REFPROP 9 and we used them in our four ORC configurations. The obtained results are given and discussed. (author)

  9. Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids

    DEFF Research Database (Denmark)

    Andreasen, Jesper Graa; Kærn, Martin Ryhl; Pierobon, Leonardo

    2016-01-01

    , which is beneficial for cycle performance. On the other hand, larger heat transfer surface areas are typically required for evaporation and condensation when zeotropic mixtures are used as working fluids. In order to assess the feasibility of using zeotropic mixtures, it is, therefore, important......For zeotropic mixtures, the temperature varies during phase change, which is opposed to the isothermal phase change of pure fluids. The use of such mixtures as working fluids in organic Rankine cycle power plants enables a minimization of the mean temperature difference of the heat exchangers...

  10. An Efficient Sleepy Algorithm for Particle-Based Fluids

    Directory of Open Access Journals (Sweden)

    Xiao Nie

    2014-01-01

    Full Text Available We present a novel Smoothed Particle Hydrodynamics (SPH based algorithm for efficiently simulating compressible and weakly compressible particle fluids. Prior particle-based methods simulate all fluid particles; however, in many cases some particles appearing to be at rest can be safely ignored without notably affecting the fluid flow behavior. To identify these particles, a novel sleepy strategy is introduced. By utilizing this strategy, only a portion of the fluid particles requires computational resources; thus an obvious performance gain can be achieved. In addition, in order to resolve unphysical clumping issue due to tensile instability in SPH based methods, a new artificial repulsive force is provided. We demonstrate that our approach can be easily integrated with existing SPH based methods to improve the efficiency without sacrificing visual quality.

  11. Sensitivity analysis of Computer-aided molecular design problem for the development of novel working fluids for power cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    is vital. Multi-criteria database search and Computer Aided Molecular Design(CAMD) can be applied to generate, test and evaluate promising pure component/mixture candidate as process fluids to help optimize cycle design and performance. The problem formulation for the development of novel working fluids...... is anadvanced CAMD challenge both in terms of data and computational demand, because includes process related as wellas property related equations.In CAMD problems the identification of target properties is often based on expert knowledge. To support identification of relevant target properties, in this study...... allows the ranking ofsignificance of properties and also the identification of a set of properties which are relevant for the design of a workingfluids.In this study the CAMD problem for the development of novel working fluids for organic Rankine cycles (ORC) isformulated as a mathematical optimization...

  12. A fluid density sensor based on a resonant tube

    International Nuclear Information System (INIS)

    Zhu, Yong; Dao, Dzung Viet; Woodfield, Peter

    2014-01-01

    A fluid density sensor based on resonance frequency change of a metallic tube is presented. The sensor has been developed without using a complex micro-fabrication process. The sensor is able to identify fluid types/contaminations and improve the performance by reducing testing time, decreasing complexity of testing equipment and reducing sample sizes. The sensor can measure the resonance frequency of its own structure and determine the change in resonance frequency due to the subsequent sample inside the tube. Numerical modelling, analytical modelling and physical testing of a prototype sensor showed comparable results for both the magnitude and resonance frequency shift. The modelling results yielded a resonance frequency shift of 200 Hz from 9.87 kHz to 9.67 kHz after the water was filled into the tube. The actual testing illustrated a resonance frequency change of 280 Hz from 9.11 kHz to 8.83 kHz. The ultimate aim of the work is to determine resonance frequencies of desired samples at a level that could detect genetic disease on a cellular level. (paper)

  13. Mechanism of chain formation in nanofluid based MR fluids

    International Nuclear Information System (INIS)

    Patel, Rajesh

    2011-01-01

    Mechanism of structure formation in bidispersed colloids is important for its physical and optical properties. It is microscopically observed that the mechanism of chain formation in magnetic nanofluid based magnetorheological (MR) fluid is quite different from that in the conventional MR fluid. Under the application of magnetic field the magnetic nanoparticles are filled inside the structural microcavities formed due to the association of large magnetic particles, and some of the magnetic nanoparticles are attached at the end of the chains formed by the large particles. The dipolar energy of the large particles in a magnetic nanofluid matrix becomes effective magnetic permeability (μ eff ) times smaller than that of the neutral medium. Inclusion of magnetic nanoparticles (∼10 nm) with large magnetic particles (∼3-5 μm) restricts the aggregation of large particles, which causes the field induced phase separation in MR fluids. Hence, nanofluid based MR fluids are more stable than conventional MR fluids, which subsequently increase their application potentiality. - Research highlights: → In bidispersed magnetic colloids nanoparticles are attached at the end of the chains formed by the large particles. → Inclusion of magnetic nanoparticles (∼10 nm) with large magnetic particles (∼3-5 m) restricts the aggregation of large particles. → Nanofluid based MR fluids are more stable than conventional MR fluids.

  14. Experimental Analysis of the Effects of Inclination Angle and Working Fluid Amount on the Performance of a Heat Pipe

    Science.gov (United States)

    Mahdavi, Mahboobe; Tiari, Saeed; Qiu, Songgang

    2016-11-01

    Heat pipes are two-phase heat transfer devices, which operate based on evaporation and condensation of a working fluid inside a sealed container. In the current work, an experimental study was conducted to investigate the performance of a copper-water heat pipe. The performance was evaluated by calculating the corresponding thermal resistance as the ratio of temperature difference between evaporator and condenser to heat input. The effects of inclination angle and the amount of working fluid were studied on the equivalent thermal resistance. The results showed that if the heat pipe is under-filled with the working fluid, energy transferring capacity of the heat pipe decreases dramatically. However, overfilling heat pipe causes over flood and degrades heat pipe performance. The minimum thermal resistances were obtained for the case that 30% of the heat pipe volume was filled with working fluid. It was also found that in gravity-assisted orientations, the inclination angle does not have significant effect on the performance of the heat pipe. However, for gravity-opposed orientations, as the inclination angle increases, the temperature difference between the evaporator and condensation increases and higher thermal resistances are obtained. Authors appreciate the financial support by a research Grant from Temple University.

  15. Thermodynamic analysis of high-temperature regenerative organic Rankine cycles using siloxanes as working fluids

    International Nuclear Information System (INIS)

    Fernandez, F.J.; Prieto, M.M.; Suarez, I.

    2011-01-01

    A recent novel adjustment of the Span-Wagner equation of state for siloxanes, used as working fluids in high-temperature organic Rankine cycles, is applied in a mathematical model to solve cycles under several working conditions. The proposed scheme includes a thermo-oil intermediate heat circuit between the heat source and the organic Rankine cycle. Linear and cyclic siloxanes are assayed in saturated, superheated and supercritical cycles. The cycle includes an internal heat exchanger (regenerative cycle), although a non-regenerative scheme is also solved. In the first part of the study, a current of combustion gases cooled to close to their dew point temperature is taken as the reference heat source. In the second part, the outlet temperature of the heat source is varied over a wide range, determining appropriate fluids and schemes for each thermal level. Simple linear (MM, MDM) siloxanes in saturated regenerative schemes show good efficiencies and ensure thermal stability of the working fluid. -- Highlights: → Organic Rankine cycles with polymethylsiloxanes as working fluids were modelled. → The cycle scheme is regenerative and includes an intermediate heat transfer fluid. → The fluid properties were calculated by means of the Span-Wagner equation of state. → Vapour conditions to the expander and source thermal level were analysed. → Siloxanes MM, MDM and D 4 under saturated conditions were the best options.

  16. Performance of V-type Stirling-cycle refrigerator for different working fluids

    Energy Technology Data Exchange (ETDEWEB)

    Tekin, Yusuf; Ataer, Omer Ercan [Erciyes University, Engineering Faculty, Mechanical Engineering Department, Melikgazi, 38 039 Kayseri (Turkey)

    2010-01-15

    The thermodynamic analysis of a V-type Stirling-cycle Refrigerator (VSR) is performed for air, hydrogen and helium as the working fluid and the performance of the VSR is investigated. The V-type Stirling-cycle refrigerator consists of expansion and compression spaces, cooler, heater and regenerator, and it is assumed that the control volumes are subjected to a periodic mass flow. The basic equations of the VSR are derived for per unit crank angle, so time does not appear in the equations. A computer program is prepared in FORTRAN, and the basic equations are solved iteratively. The mass, temperature and density of working fluid in each control volume are calculated for different charge pressures, engine speeds, and for fixed heater and cooler surface temperatures. The work, instantaneous pressure and the COP of the VSR are calculated. The results are obtained for different working fluids, and given by diagrams. (author)

  17. The Contribution of Working Memory to Fluid Reasoning: Capacity, Control, or Both?

    Science.gov (United States)

    Chuderski, Adam; Necka, Edward

    2012-01-01

    Fluid reasoning shares a large part of its variance with working memory capacity (WMC). The literature on working memory (WM) suggests that the capacity of the focus of attention responsible for simultaneous maintenance and integration of information within WM, as well as the effectiveness of executive control exerted over WM, determines…

  18. Carbon dioxide as working fluid for medium and high-temperature concentrated solar thermal systems

    Directory of Open Access Journals (Sweden)

    Van Duong

    2014-03-01

    Full Text Available This paper explores the benefits and drawbacks of using carbon dioxide in solar thermal systems at medium and high operating temperatures. For medium temperatures, application of CO2 in non-imaging-optics based compound parabolic concentrators (CPC combined with evacuated-tube collectors is studied. These collectors have been shown to obtain efficiencies higher than 40% operating at around 200℃ without the need of tracking. Validated numerical models of external compound parabolic concentrators (XCPCs are used to simulate their performance using CO2 as working fluid. For higher temperatures, a mathematical model is implemented to analyze the operating performance of a parabolic trough solar collector (PTC using CO2 at temperatures between 100℃ and 600℃.

  19. Local composition shift of mixed working fluid in gas–liquid flow with phase transition

    International Nuclear Information System (INIS)

    Xu Xiongwen; Liu Jinping; Cao Le; Li Zeyu

    2012-01-01

    Local composition shift is an important characteristic of gas-liquid mixture flow with phase transition. It affects the heat transfer process, stream sonic velocity and the mixture distribution in the thermodynamic cycle. Presently, it is mainly calculated through the empirical models of the void fraction from pure fluid experiments. In this paper, we made efforts to obtain it and its rules basing on conservation equations derivation. The result calculated with propane/i-butane binary mixture was verified by the experiment in the evaporator of a refrigerator. As an extending, it was applied to a ternary mixture with components of methane, propane and butane and more information was presented and analyzed. The calculation approach presented in this paper can be applied any multicomponent mixture, and the rules will be helpful to improve the composition shift theory. - Highlights: ► Local composition shift of mixed working fluid in gas–liquid flow was modelled. ► A solution method for local composition of gas–liquid flow was proposed. ► The solution method was verified by the experimental result. ► Local composition shift mechanism of gas–liquid flow was studied

  20. Cognitive predictors of a common multitasking ability: Contributions from working memory, attention control, and fluid intelligence.

    Science.gov (United States)

    Redick, Thomas S; Shipstead, Zach; Meier, Matthew E; Montroy, Janelle J; Hicks, Kenny L; Unsworth, Nash; Kane, Michael J; Hambrick, D Zachary; Engle, Randall W

    2016-11-01

    Previous research has identified several cognitive abilities that are important for multitasking, but few studies have attempted to measure a general multitasking ability using a diverse set of multitasks. In the final dataset, 534 young adult subjects completed measures of working memory (WM), attention control, fluid intelligence, and multitasking. Correlations, hierarchical regression analyses, confirmatory factor analyses, structural equation models, and relative weight analyses revealed several key findings. First, although the complex tasks used to assess multitasking differed greatly in their task characteristics and demands, a coherent construct specific to multitasking ability was identified. Second, the cognitive ability predictors accounted for substantial variance in the general multitasking construct, with WM and fluid intelligence accounting for the most multitasking variance compared to attention control. Third, the magnitude of the relationships among the cognitive abilities and multitasking varied as a function of the complexity and structure of the various multitasks assessed. Finally, structural equation models based on a multifaceted model of WM indicated that attention control and capacity fully mediated the WM and multitasking relationship. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  1. A Comparison of Laboratory and Clinical Working Memory Tests and Their Prediction of Fluid Intelligence

    Science.gov (United States)

    Shelton, Jill T.; Elliott, Emily M.; Hill, B. D.; Calamia, Matthew R.; Gouvier, Wm. Drew

    2010-01-01

    The working memory (WM) construct is conceptualized similarly across domains of psychology, yet the methods used to measure WM function vary widely. The present study examined the relationship between WM measures used in the laboratory and those used in applied settings. A large sample of undergraduates completed three laboratory-based WM measures (operation span, listening span, and n-back), as well as the WM subtests from the Wechsler Adult Intelligence Scale-III and the Wechsler Memory Scale-III. Performance on all of the WM subtests of the clinical batteries shared positive correlations with the lab measures; however, the Arithmetic and Spatial Span subtests shared lower correlations than the other WM tests. Factor analyses revealed that a factor comprising scores from the three lab WM measures and the clinical subtest, Letter-Number Sequencing (LNS), provided the best measurement of WM. Additionally, a latent variable approach was taken using fluid intelligence as a criterion construct to further discriminate between the WM tests. The results revealed that the lab measures, along with the LNS task, were the best predictors of fluid abilities. PMID:20161647

  2. A field application of nanoparticle-based invert emulsion drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, Alexey S.; Husein, Maen, E-mail: mhusein@ucalgary.ca [University of Calgary, Department of Chemical & Petroleum Engineering (Canada); Hareland, Geir [Oklahoma State University, Department of Chemical Engineering (United States)

    2015-08-15

    Application of nanotechnology in drilling fluids for the oil and gas industry has been a focus of several recent studies. A process for the in situ synthesis of nanoparticles (NPs) into drilling fluids has been developed previously in our group and showed that calcium-based NPs (CNPs) and iron-based NPs (INPs), respectively, with concentrations of 0.5–2.0 wt% can dramatically improve filtration properties of commercial drilling fluids in a laboratory environment. In this work, a modified process for the emulsion-based synthesis of NPs on a 20 m{sup 3} volume and its subsequent full-scale field testing are presented. Comparison between NP carrier fluids prepared under controlled environment in the laboratory and those prepared on a large scale in a mixing facility revealed very little variation in the main characteristics of the drilling fluid; including the size of the solid constituents. Transmission electron microscopy photographs suggest an average CNP particle size in the carrier fluid of 51 ± 11 nm. Results from the full-scale field test showed that total mud losses while drilling with CNP-based invert emulsion were on average 27 % lower than in the case of conventional fluids. This loss prevention falls within the range observed in the laboratory.

  3. Magnetorheological fluid based on thixotropic PTFE-oil organogel

    Science.gov (United States)

    Zhang, Hansong; Yan, Hua; Hu, Zhide; Yang, Jianjian; Niu, Fanghao

    2018-04-01

    Polytetrafluoroethylene (PTFE) micropowders were employed in this work to fabricate PTFE-oil organogel, then carbonyl iron particles were dispersed in this thixotropic organogel to prepare magnetorheological fluids without any other additives. By performing a comparative investigation of MRFs' performances, enhanced magnetorheological response, suspension stability and tribological performance were obtained contrast to pure silicon oil based MRFs. The experimental results revealed a changeable viscosity of organogel, considerable increases in thixotropy also can be observed with the increase of PTFE content. Sedimentation tests demonstrated a much better suspension stability of MRFs based on organogel, suggesting that the internal network microstructures formed by hydrogen bonds between PTFE microparticles and oil molecular chains are likely to impose the gaps among magnetic particles thus hinder the particle aggregation and sedimentation. Moreover, a critical PTFE volume fraction about 4.7 vol% was recognized in this study, lower content organogels tended to display enhanced yield stresses contrast to pure silicon oil based MRFs while high content organogels showed slightly lower ones. It may suggest a compromise between nonmagnetic particle adsorption and the reinforcement effect of network microstructures. The adsorption is likely to decrease the saturation magnetization of carbonyl iron particles and to hinder the formation of field-induced chains, however, the reinforcement effect tends to strengthen these magnetic chains. Besides, the tribological tests confirmed the lubricant effects of PTFE-oil organogel by acquiring rather sharp decreases in friction coefficients of organogel based MRFs especially in the presence of magnetic field.

  4. Analysis of thermal cycles and working fluids for power generation in space

    International Nuclear Information System (INIS)

    Tarlecki, Jason; Lior, Noam; Zhang Na

    2007-01-01

    Production of power in space for terrestrial use is of great interest in view of the rapidly rising power demand and its environmental impacts. Space also offers a very low temperature, making it a perfect heat sink for power plants, thus offering much higher efficiencies. This paper focuses on the evaluation and analysis of thermal Brayton, Ericsson and Rankine power cycles operating at space conditions on several appropriate working fluids. Under the examined conditions, the thermal efficiency of Brayton cycles reaches 63%, Ericsson 74%, and Rankine 85%. These efficiencies are significantly higher than those for the computed or real terrestrial cycles: by up to 45% for the Brayton, and 17% for the Ericsson; remarkably 44% for the Rankine cycle even when compared with the best terrestrial combined cycles. From the considered working fluids, the diatomic gases (N 2 and H 2 ) produce somewhat better efficiencies than the monatomic ones in the Brayton and Rankine cycles. The Rankine cycles require radiator areas that are larger by up to two orders of magnitude than those required for the Brayton and Ericsson cycles. The results of the analysis of the sensitivity of the cycle performance parameters to major parameters such as turbine inlet temperature and pressure ratio are presented, equations or examining the effects of fluid properties on the radiator area and pressure drop were developed, and the effects of the working fluid properties on cycle efficiency and on the power production per unit radiator area were explored to allow decisions on the optimal choice of working fluids

  5. Evaluation of a solar-powered organic Rankine cycle using dry organic working fluids

    Directory of Open Access Journals (Sweden)

    Emily Spayde

    2015-12-01

    Full Text Available This paper presents a model to evaluate the performance of a solar-powered organic Rankine cycle (ORC. The system was evaluated in Jackson, MS, using five dry organic working fluids, R218, R227ea, R236ea, R236fa, and RC318. The purpose of this study is to investigate how hourly temperature change affects the electricity production and exergy destruction rates of the solar ORC, and to determine the effect of the working fluid on the proposed system. The system was also evaluated in Tucson, AZ, to investigate the effect of average hourly outdoor temperatures on its performance. The potential of the system to reduce primary energy consumption and carbon dioxide emissions is also investigated. A parametric analysis to determine how temperature and pressure of the organic working fluid, the solar collector area, and the turbine efficiency affect the electricity production is performed. Results show that the ORC produces the most electricity during the middle of the day, when the temperatures are the highest and when the solar collectors have the highest efficiency. Also, R-236ea is the working fluid that shows the best performance of the evaluated fluids. An economic analysis was performed to determine the capital cost available for the proposed system.

  6. Selection of Optimum Working Fluid for Organic Rankine Cycles by Exergy and Exergy-Economic Analyses

    Directory of Open Access Journals (Sweden)

    Kamyar Darvish

    2015-11-01

    Full Text Available The thermodynamic performance of a regenerative organic Rankine cycle that utilizes low temperature heat sources to facilitate the selection of proper organic working fluids is simulated. Thermodynamic models are used to investigate thermodynamic parameters such as output power, and energy efficiency of the ORC (Organic Rankine Cycle. In addition, the cost rate of electricity is examined with exergo-economic analysis. Nine working fluids are considered as part of the investigation to assess which yields the highest output power and exergy efficiency, within system constraints. Exergy efficiency and cost rate of electricity are used as objective functions for system optimization, and each fluid is assessed in terms of the optimal operating condition. The degree of superheat and the pressure ratio are independent variables in the optimization. R134a and iso-butane are found to exhibit the highest energy and exergy efficiencies, while they have output powers in between the systems using other working fluids. For a source temperature was equal to 120 °C, the exergy efficiencies for the systems using R134a and iso-butane are observed to be 19.6% and 20.3%, respectively. The largest exergy destructions occur in the boiler and the expander. The electricity cost rates for the system vary from 0.08 USD/kWh to 0.12 USD/kWh, depending on the fuel input cost, for the system using R134a as a working fluid.

  7. Property Uncertainty Analysis and Methods for Optimal Working Fluids of Thermodynamic Cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome

    in the context of an industrial organic Rankine cycle, used for the recovery of waste heat from an engine of a marine container ship. The study illustrates that the model structure is vital for the uncertainties of equations of state and suggests that uncertainty becomes a criterion (along with e.g. goodness......-of-fit or ease of use) for the selection of an equation of state for a specific application. Furthermore, two studies on the identification of suitable working fluids for thermodynamic cycles are presented. The first one selects and assesses working fluid candidates for an organic Rankine cycle system to recover......There is an increasing interest in recovering industrial waste heat at low tempera-tures (70-250◦C). Thermodynamic cycles, such as heat pumps or organic Rankine cycles, can recover this heat and transfer it to other process streams or convert it into electricity. The working fluid, circulating...

  8. Planning Decrements in Healthy Aging: Mediation Effects of Fluid Reasoning and Working Memory Capacity.

    Science.gov (United States)

    Köstering, Lena; Leonhart, Rainer; Stahl, Christoph; Weiller, Cornelius; Kaller, Christoph P

    2016-03-01

    Although age-related differences in planning ability are well known, their cognitive foundations remain a matter of contention. To elucidate the specific processes underlying planning decrements in older age, the relative contributions of fluid reasoning, working memory (WM) capacity, and processing speed to accuracy on the Tower of London (TOL) planning task were investigated. Mediation analyses were used to relate overall and search depth-related TOL accuracy from older (N = 106; 60-89 years) and younger adults (N = 69; 18-54 years) to age and measures of fluid reasoning, WM capacity, and speed. For overall planning, fluid abilities mediated the effects of age, WM capacity, and speed in older adults. By contrast, fluid abilities and WM capacity mediated each other in younger adults. For planning accuracy under low demands on the depth of search, WM capacity was specifically important in older age, whereas younger adults recruited both WM capacity and fluid reasoning. Under high search-depth-demands, fluid abilities underlay the cognitive operations critical for resolving move interdependencies in both age groups. Fluid abilities and WM capacity undergo significant changes from younger to older age in their unique contribution to planning, which might represent a mechanism whereby planning decrements in older age are brought about. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Performance analysis and binary working fluid selection of combined flash-binary geothermal cycle

    International Nuclear Information System (INIS)

    Zeyghami, Mehdi

    2015-01-01

    Performance of the combined flash-binary geothermal power cycle for geofluid temperatures between 150 and 250 °C is studied. A thermodynamic model is developed, and the suitable binary working fluids for different geofluid temperatures are identified from a list of thirty working fluid candidates, consisting environmental friendly refrigerants and hydrocarbons. The overall system exergy destruction and Vapor Expansion Ratio across the binary cycle turbine are selected as key performance indicators. The results show that for low-temperature heat sources using refrigerants as binary working fluids result in higher overall cycle efficiency and for medium and high-temperature resources, hydrocarbons are more suitable. For combined flash-binary cycle, secondary working fluids; R-152a, Butane and Cis-butane show the best performances at geofluid temperatures 150, 200 and 250 °C respectively. The overall second law efficiency is calculated as high as 0.48, 0.55 and 0.58 for geofluid temperatures equal 150, 200 and 250 °C respectively. The flash separator pressure found to has important effects on cycle operation and performance. Separator pressure dictates the work production share of steam and binary parts of the system. And there is an optimal separator pressure at which overall exergy destruction of the cycle achieves its minimum value. - Highlights: • Performance of the combined flash-binary geothermal cycle is investigated. • Thirty different fluids are screened to find the most suitable ORC working fluid. • Optimum cycle operation conditions presented for geofluids between 150 °C and 250 °C. • Refrigerants are more suitable for the ORC at geothermal sources temperature ≤200 °C. • Hydrocarbons are more suitable for the ORC at geothermal sources temperature >200 °C

  10. High-water-base hydraulic fluid-irradiation experiments

    International Nuclear Information System (INIS)

    Bradley, E.C.; Meacham, S.A.

    1981-10-01

    A remote system for shearing spent nuclear fuel assemblies is being designed under the direction of the Consolidated Fuel Reprocessing Program (CFRP). The design incorporates a dual hydraulic fluid actuation system in which only one of the fluids, a high-water-base (HWBF), would be exposed to ionizing radiation and radioactive contamination. A commercially available synthetic, solution-type HWBF was selected as the reference. Single-sample irradiation experiments were conducted with three commercial fluids over a range of irradiation exposures. The physical and chemical properties of the irradiated HWBFs were analyzed and compared with unirradiated samples. In general, the results of the analyses showed increasing degradation of fluid properties with increasing irradiation dose. The results also indicated that a synthetic solution-type HWBF would perform satisfactorily in the remote shear system where irradiation doses up to 10 6 Gy (10 8 rad) are expected

  11. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong

    2015-12-28

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil "electrical sensitivity." Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems. © ASCE.

  12. Fines classification based on sensitivity to pore-fluid chemistry

    Science.gov (United States)

    Jang, Junbong; Santamarina, J. Carlos

    2016-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil “electrical sensitivity.” Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems.

  13. High-water-base hydraulic fluid-irradiation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, E.C.; Meacham, S.A.

    1981-10-01

    A remote system for shearing spent nuclear fuel assemblies is being designed under the direction of the Consolidated Fuel Reprocessing Program (CFRP). The design incorporates a dual hydraulic fluid actuation system in which only one of the fluids, a high-water-base (HWBF), would be exposed to ionizing radiation and radioactive contamination. A commercially available synthetic, solution-type HWBF was selected as the reference. Single-sample irradiation experiments were conducted with three commercial fluids over a range of irradiation exposures. The physical and chemical properties of the irradiated HWBFs were analyzed and compared with unirradiated samples. In general, the results of the analyses showed increasing degradation of fluid properties with increasing irradiation dose. The results also indicated that a synthetic solution-type HWBF would perform satisfactorily in the remote shear system where irradiation doses up to 10/sup 6/ Gy (10/sup 8/ rad) are expected.

  14. Experimental study of high-performance cooling system pipeline diameter and working fluid amount

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan; Hrabovsky, Peter; Papučík, Štefan

    2016-03-01

    This work deals with heat transfer resulting from the operation of power electronic components. Heat is removed from the mounting plate, which is the evaporator of the loop thermosyphon to the condenser and by natural convection is transferred to ambient. This work includes proposal of cooling device - loop thermosyphon, with its construct and follow optimization of cooling effect. Optimization proceeds by selecting the quantity of working fluid and selection of diameters vapour line and liquid line of loop thermosyphon.

  15. Influence of working fluids on Organic Rankine Cycle for waste heat recovery applications

    Energy Technology Data Exchange (ETDEWEB)

    Struzyna, Ralf; Eifler, Wolfgang; Steinmill, Jens [Bochum Univ. (Germany). Lehrstuhl fuer Verbrennungsmotoren

    2012-11-01

    More than 50% of the energy contained in fuel is lost due to the loss of heat content to the exhaust gas, the cooling water or the charge air cooler medium. Therefore, one of the most promising attempts to further increase the efficiency of internal combustion engines is waste heat recovery by means of a combined process. The Organic Rankine Cycle (ORC) is a promising process for waste heat recovery systems. The main purpose is to identify suitable working fluids to achieve best system performance. Therefore an analysis of the influence of different working fluids on system output is required. (orig.)

  16. A Quality Function Deployment-Based Model for Cutting Fluid Selection

    Directory of Open Access Journals (Sweden)

    Kanika Prasad

    2016-01-01

    Full Text Available Cutting fluid is applied for numerous reasons while machining a workpiece, like increasing tool life, minimizing workpiece thermal deformation, enhancing surface finish, flushing away chips from cutting surface, and so on. Hence, choosing a proper cutting fluid for a specific machining application becomes important for enhanced efficiency and effectiveness of a manufacturing process. Cutting fluid selection is a complex procedure as the decision depends on many complicated interactions, including work material’s machinability, rigorousness of operation, cutting tool material, metallurgical, chemical, and human compatibility, reliability and stability of fluid, and cost. In this paper, a decision making model is developed based on quality function deployment technique with a view to respond to the complex character of cutting fluid selection problem and facilitate judicious selection of cutting fluid from a comprehensive list of available alternatives. In the first example, HD-CUTSOL is recognized as the most suitable cutting fluid for drilling holes in titanium alloy with tungsten carbide tool and in the second example, for performing honing operation on stainless steel alloy with cubic boron nitride tool, CF5 emerges out as the best honing fluid. Implementation of this model would result in cost reduction through decreased manpower requirement, enhanced workforce efficiency, and efficient information exploitation.

  17. A contemporary look at Hermann Hankel's 1861 pioneering work on Lagrangian fluid dynamics

    Science.gov (United States)

    Frisch, Uriel; Grimberg, Gérard; Villone, Barbara

    2017-12-01

    The present paper is a companion to the paper by Villone and Rampf (2017), titled "Hermann Hankel's On the general theory of motion of fluids, an essay including an English translation of the complete Preisschrift from 1861" together with connected documents [Eur. Phys. J. H 42, 557-609 (2017)]. Here we give a critical assessment of Hankel's work, which covers many important aspects of fluid dynamics considered from a Lagrangian-coordinates point of view: variational formulation in the spirit of Hamilton for elastic (barotropic) fluids, transport (we would now say Lie transport) of vorticity, the Lagrangian significance of Clebsch variables, etc. Hankel's work is also put in the perspective of previous and future work. Hence, the action spans about two centuries: from Lagrange's 1760-1761 Turin paper on variational approaches to mechanics and fluid mechanics problems to Arnold's 1966 founding paper on the geometrical/variational formulation of incompressible flow. The 22-year-old Hankel - who was to die 12 years later — emerges as a highly innovative master of mathematical fluid dynamics, fully deserving Riemann's assessment that his Preisschrift contains "all manner of good things."

  18. Preliminary assessment of water-based nano-fluids for use as coolants in PWRs

    International Nuclear Information System (INIS)

    Jacopo Buongiorno

    2005-01-01

    Full text of publication follows: The impact of using water-based fluids with small additions (<2% vol.) of nano-sized (10-100 nm) particle populations as coolants for current and advanced PWRs is evaluated. Such 'engineered' fluids (known as nano-fluids) are attractive because the presence of the nano-particles enhances energy transport considerably. As a result, nano-fluids are known to have (i) higher thermal conductivity than water (up to 20% depending on nano-particle material, size and volumetric fraction), (ii) higher heat transfer coefficients (up to 40%), (iii) higher CHF (up to 300% in pool boiling), and (iv) comparable pressure drop. Furthermore, nano-fluids appear to be very stable suspensions with little or no sedimentation, because of the small size of the dispersed particles and their typically low volumetric fractions. The ultimate objective of this work is to assess whether existing PWRs could be retro-fitted with a water-based nano-fluid coolant, to increase safety margins, reduce stored energy, and/or allow for power up-rates. Also, advanced PWRs could be designed with nano-fluids. The linear heat generation rate in PWRs is limited by a) fuel centerline melting, b) cladding overheating (CHF), and c) stored energy release following a large-break LOCA. Mechanisms b) and c) are usually the most limiting. For given geometry and linear power, it is obvious that the core with the nano-fluid coolant will have higher margins to CHF and LOCA limits. Conversely, for given margins, a higher linear power can be accommodated by the nano-fluid-cooled core. Standard thermal-hydraulic models for the PWR hot fuel pin (including a RELAP model for the LOCA) have been used to quantify the benefit of using nano-fluid coolants on the performance of a PWR. (author)

  19. Working regime identification for natural circulation loops by comparative thermalhydraulic analyses with three fluids under identical operating conditions

    International Nuclear Information System (INIS)

    Sarkar, Milan K.S.; Basu, Dipankar N.

    2015-01-01

    Highlights: • Thermalhydraulic analyses of NCL to justify the use of supercritical condition. • Mass flow rate of supercritical loop increases with heater power till a maxima. • Supercritical loop suffer from HTD beyond the maxima with jump in fluid temperature. • HTD is pronounced at higher sink temperatures and pressures just above critical. • Supercritical CO_2 is preferred fluid till the HTD and single-phase water afterwards. - Abstract: Computational investigation for comparative thermalhydraulic analyses of rectangular natural circulation loops is performed to propose a guideline for selecting the working fluid and nature of the loop, subcritical or supercritical, under identical levels of operating parameters like pressure, heating power and coolant temperature. A 3-d uniform-diameter loop geometry is developed with horizontal heating and cooling. Heating is provided in constant heat flux mode, whereas cooling is through a constant temperature sink. Due to favourable thermophysical properties and environmental conformity, water, CO_2 and R134a are selected as possible working fluids. Operational parameters are set so as to have sub- to supercritical condition for CO_2, supercritical for R134a and single-phase liquid for water. Mass flow rate for supercritical fluid rapidly increases with heater power, when the fluid is allowed to cross the pseudocritical point during its passage through the heater, and exhibits a maxima. Drastic fall in mass flow rate can be observed beyond the maxima, accompanied by a jump in maximum fluid temperature and a rapid decline in sink-side heat transfer coefficient. That can be identified as heat transfer deterioration in supercritical natural circulation loops, a highly undesirable situation from loop safety point of view. Allowable working range of heater power can be enhanced by increasing system pressure and decreasing sink temperature. For any specified set of operating conditions, CO_2-based supercritical loops

  20. Working regime identification for natural circulation loops by comparative thermalhydraulic analyses with three fluids under identical operating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Milan K.S.; Basu, Dipankar N., E-mail: dipankar.n.basu@gmail.com

    2015-11-15

    Highlights: • Thermalhydraulic analyses of NCL to justify the use of supercritical condition. • Mass flow rate of supercritical loop increases with heater power till a maxima. • Supercritical loop suffer from HTD beyond the maxima with jump in fluid temperature. • HTD is pronounced at higher sink temperatures and pressures just above critical. • Supercritical CO{sub 2} is preferred fluid till the HTD and single-phase water afterwards. - Abstract: Computational investigation for comparative thermalhydraulic analyses of rectangular natural circulation loops is performed to propose a guideline for selecting the working fluid and nature of the loop, subcritical or supercritical, under identical levels of operating parameters like pressure, heating power and coolant temperature. A 3-d uniform-diameter loop geometry is developed with horizontal heating and cooling. Heating is provided in constant heat flux mode, whereas cooling is through a constant temperature sink. Due to favourable thermophysical properties and environmental conformity, water, CO{sub 2} and R134a are selected as possible working fluids. Operational parameters are set so as to have sub- to supercritical condition for CO{sub 2}, supercritical for R134a and single-phase liquid for water. Mass flow rate for supercritical fluid rapidly increases with heater power, when the fluid is allowed to cross the pseudocritical point during its passage through the heater, and exhibits a maxima. Drastic fall in mass flow rate can be observed beyond the maxima, accompanied by a jump in maximum fluid temperature and a rapid decline in sink-side heat transfer coefficient. That can be identified as heat transfer deterioration in supercritical natural circulation loops, a highly undesirable situation from loop safety point of view. Allowable working range of heater power can be enhanced by increasing system pressure and decreasing sink temperature. For any specified set of operating conditions, CO{sub 2}-based

  1. Comparative investigation of working fluids for an organic Rankine cycle with geothermal water

    Directory of Open Access Journals (Sweden)

    Liu Yan-Na

    2015-06-01

    Full Text Available In this paper, the thermodynamic investigation on the use of geothermal water (130 °C as maximum for power generation through a basic Rankine has been presented together with obtained main results. Six typical organic working fluids (i.e., R245fa, R141b, R290, R600, R152a, and 134a were studied with modifying the input pressure and temperature to the turbine. The results show that there are no significant changes taking place in the efficiency for these working fluids with overheating the inlet fluid to the turbine, i.e., efficiency is a weak function of temperature. However, with the increasing of pressure ratio in the turbine, the efficiency rises more sharply. The technical viability is shown of implementing this type of process for recovering low temperature heat resource.

  2. Replacement of petroleum based hydraulic fluids with renewable and environmental friendly resource

    International Nuclear Information System (INIS)

    Wan Sani Wan Nik; Noraini Ali

    2000-01-01

    Rational self-interest and good environmental citizenship are forcing the development of renewable and environmentally acceptable hydraulic fluids. Fluids that are at least equivalent in performance plus biodegradable have been formulated in Europe and USA using vegetable oils as base stocks for innovative additive packages. While many of the differences in using vegetable based stocks in place of mineral oils have been adapted to by straightforward formulating changes, the oxidation stability of vegetable-based stock is still a challenging area. This work initiates the investigation in Malaysia in the use of environmentally friendly resource to replace partially the petroleum based hydraulic fluid. The study concentrates more in improving the oxidation stability of the vegetable based stocks. (Author)

  3. Working Memory Capacity and Fluid Abilities: Examining the Correlation between Operation Span and Raven

    Science.gov (United States)

    Unsworth, N.; Engle, R.W.

    2005-01-01

    The correlation between a measure of working memory capacity (WMC) (Operation Span) and a measure of fluid abilities (Raven Advanced Progressive Matrices) was examined. Specifically, performance on Raven problems was decomposed by difficulty, memory load, and rule type. The results suggest that the relation between Operation Span and Raven is…

  4. Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids

    Directory of Open Access Journals (Sweden)

    Jesper G. Andreasen

    2016-04-01

    Full Text Available For zeotropic mixtures, the temperature varies during phase change, which is opposed to the isothermal phase change of pure fluids. The use of such mixtures as working fluids in organic Rankine cycle power plants enables a minimization of the mean temperature difference of the heat exchangers, which is beneficial for cycle performance. On the other hand, larger heat transfer surface areas are typically required for evaporation and condensation when zeotropic mixtures are used as working fluids. In order to assess the feasibility of using zeotropic mixtures, it is, therefore, important to consider the additional costs of the heat exchangers. In this study, we aim at evaluating the economic feasibility of zeotropic mixtures compared to pure fluids. We carry out a multi-objective optimization of the net power output and the component costs for organic Rankine cycle power plants using low-temperature heat at 90 ∘ C to produce electrical power at around 500 kW. The primary outcomes of the study are Pareto fronts, illustrating the power/cost relations for R32, R134a and R32/R134a (0.65/0.35 mole . The results indicate that R32/R134a is the best of these fluids, with 3.4 % higher net power than R32 at the same total cost of 1200 k$.

  5. Transfer effects after working memory training lead to improved fluid intelligence

    OpenAIRE

    Onken, Johanna

    2013-01-01

    Fluid intelligence describes the ability to think abstract, to adapt to new situations and to solve unknown problems. It is important for learning as well as for academic and professional success. Working memory is characterized as a cognitive system, that saves information over a short period of time in spite of possible distractions. More- over, working memory is able to assess the relevance of information while requirements change. Effective implicit training is able to increase the workin...

  6. A potential spatial working memory training task to improve both episodic memory and fluid intelligence.

    Directory of Open Access Journals (Sweden)

    Sarah R Rudebeck

    Full Text Available One current challenge in cognitive training is to create a training regime that benefits multiple cognitive domains, including episodic memory, without relying on a large battery of tasks, which can be time-consuming and difficult to learn. By giving careful consideration to the neural correlates underlying episodic and working memory, we devised a computerized working memory training task in which neurologically healthy participants were required to monitor and detect repetitions in two streams of spatial information (spatial location and scene identity presented simultaneously (i.e. a dual n-back paradigm. Participants' episodic memory abilities were assessed before and after training using two object and scene recognition memory tasks incorporating memory confidence judgments. Furthermore, to determine the generalizability of the effects of training, we also assessed fluid intelligence using a matrix reasoning task. By examining the difference between pre- and post-training performance (i.e. gain scores, we found that the trainers, compared to non-trainers, exhibited a significant improvement in fluid intelligence after 20 days. Interestingly, pre-training fluid intelligence performance, but not training task improvement, was a significant predictor of post-training fluid intelligence improvement, with lower pre-training fluid intelligence associated with greater post-training gain. Crucially, trainers who improved the most on the training task also showed an improvement in recognition memory as captured by d-prime scores and estimates of recollection and familiarity memory. Training task improvement was a significant predictor of gains in recognition and familiarity memory performance, with greater training improvement leading to more marked gains. In contrast, lower pre-training recollection memory scores, and not training task improvement, led to greater recollection memory performance after training. Our findings demonstrate that practice

  7. Multiphase numerical analysis of heat pipe with different working fluids for solar applications

    Science.gov (United States)

    Aswath, S.; Netaji Naidu, V. H.; Padmanathan, P.; Raja Sekhar, Y.

    2017-11-01

    Energy crisis is a prognosis predicted in many cases with the indiscriminate encroachment of conventional energy sources for applications on a massive scale. This prediction, further emboldened by the marked surge in global average temperatures, attributed to climate change and global warming, the necessity to conserve the environment and explore alternate sources of energy is at an all-time high. Despite being among the lead candidates for such sources, solar energy is utilized far from its vast potential possibilities due to predominant economic constraints. Even while there is a growing need for solar panels at more affordable rates, the other options to harness better out of sun’s energy is to optimize and improvise existing technology. One such technology is the heat pipe used in Evacuated Tube Collectors (ETC). The applications of heat pipe have been gaining momentum in various fields since its inception and substantial volumes of research have explored optimizing and improving the technology which is proving effective in heat recovery and heat transfer better than conventional systems. This paper carries out a computational analysis on a comparative simulation between two working fluids within heat pipe of same geometry. It further endeavors to study the multiphase transitions within the heat pipe. The work is carried out using ANSYS Fluent with inputs taken from solar data for the location of Vellore, Tamil Nadu. A wickless, gravity-assisted heat pipe (GAHP) is taken for the simulation. Water and ammonia are used as the working fluids for comparative multiphase analysis to arrive at the difference in heat transfer at the condenser section. It is demonstrated that a heat pipe ETC with ammonia as working fluid showed higher heat exchange (temperature difference) as against that of water as working fluid. The multiphase model taken aided in study of phase transitions within both cases and supported the result of ammonia as fluid being a better candidate.

  8. Multi-objective optimization of organic Rankine cycle power plants using pure and mixed working fluids

    DEFF Research Database (Denmark)

    Andreasen, Jesper Graa; Kærn, Martin Ryhl; Pierobon, Leonardo

    2015-01-01

    For zeotropic mixtures, the temperature varies during phase change, which is opposed to the isothermalphase change of pure fluids. The use of such mixtures as working fluids in organic Rankine cyclepower plants enables a minimization of the mean temperature difference of the heat exchangers whenthe...... minimum pinch point temperature difference is kept fixed. A low mean temperature differencemeans low heat transfer irreversibilities, which is beneficial for cycle performance, but it also results inlarger heat transfer surface areas. Moreover, the two-phase heat transfer coefficients for zeotropic...

  9. Polyalkylene glycols, base fluids for special lubricants and hydraulic fluids; Polyalkylenglykole, Basisoele fuer Spezialschmierstoffe und Hydraulikfluessigkeiten

    Energy Technology Data Exchange (ETDEWEB)

    Poellmann, K. [Clariant GmbH (Germany)

    2004-08-01

    For many years polyalkylene glycols have been used as base fluids for special lubricants. In this matter they compete with polyol esters and polyalphaolefines. Synthesis of polyalkylen glycols is founded upon the anionic polymerisation of ethyleneoxid, propyleneoxid and if necessary of other oxigen-containing monomeres. The flexibility of this synthesis is the reason that polyalkylene glycole is a collective term, including a broad group of base fluids with partly extreme different properties. Typical for polyalkylene glycols is a high viscosity-index, watersolubility and adsorbing power for water, low friction numbers, but also the incompatibility with current mineral-oil-soluble additive systems. Because of this quality profile there has been developped specific niche-applications in the lubricant-area for polyalkylene glycols in the last 30 years, where each of the specific benefits has been used. Among them are watercontaining HFC hydraulicfluids, refrigerator oils, and oils for ethylene-compressors. HFC fluids are formulated with high-viscous, water-soluble polyalkylene glycols. For refrigerator oils in motor-car conditioning the R 134A compatibility of water-insoluble polyalkylene glycols is essential. For the use in ethylene-compressors the crucial point is the insolubility of polyalkylene glycol in ethylene. (orig.)

  10. Performances of cutting fluids in turning. Vegetable based oil - RV

    DEFF Research Database (Denmark)

    Axinte, Dragos Aurelian; Belluco, Walter

    1999-01-01

    Scope of the present measurement campaign is the evaluation of the cutting fluid performance. The report presents the standard routine and the results obtained when turning stainless steel and brass with a commercial vegetable based oil called RV. The methods were developed to be applicable...

  11. A Study Of Magnetic Fluid Based Squeeze Film Between Porous ...

    African Journals Online (AJOL)

    Efforts have been made to study and analyze the effect of surface roughness on the performance of magnetic fluid based squeeze film between porous elliptic plates. The transverse roughness of the bearing surface is characterized by a stochastic random variable with non-zero mean, variance and skewness.

  12. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong; Santamarina, Carlos

    2015-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing

  13. Drilling fluid base oil biodegradation potential of a soil ...

    African Journals Online (AJOL)

    Staphylococcus sp. isolated from oil-contaminated soil was grown in 1% drilling fluid base oil, HDF- 2000, as a sole source of carbon and energy. The organism has strong affinity for the substrate, growing at the rate of 0.16 h-1. It uses adherence and emulsification as mechanisms for oil uptake. In a nutrient-rich marine ...

  14. Mixture of working fluids in ORC plants with pool boiler evaporator

    International Nuclear Information System (INIS)

    Rajabloo, Talieh; Iora, Paolo; Invernizzi, Costante

    2016-01-01

    Highlights: • We assess the feasibility of pool boiler in ORCs operating with mixture working fluids. • We consider hydrocarbon and siloxane mixtures for low and high temperature ORCs. • Plants with pool boiler show comparable performances to once through evaporator. - Abstract: Power generation using Organic Rankine Cycle was studied in this paper in case of both low and high temperature cycles, exploiting respectively a geothermal heat source available at 167 °C, and heat available at 300 °C from the combustion of biomass. In particular we assess the feasibility of employing mixture of working fluids, in the case of replacing the typical once-through (OT) evaporator with the pool boiler (PB) technology, typically adopted for pure fluids. The analysis evidenced that in general the OT evaporator shows a slightly improved cycle performance in comparison to the PB and it results in some cases advantageous with respect to the pure working fluid. For instance in case of low temperature cycle, the best thermodynamic performances are obtained with mixture of i-C_5 and 75% n-C_4 in case of OT evaporator, yielding a recovery efficiency higher than the case with pure i-C_5 (7.7 vs. 7.4%) given the relatively higher values of both the recovery factor and cycle efficiency. Implementation of PB did not affect the plant performance significantly which shows the feasibility of having PB with potentially easier control.

  15. Optimization of morphing flaps based on fluid structure interaction modeling

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Akay, Busra

    2018-01-01

    This article describes the design optimization of morphing trailing edge flaps for wind turbines with ‘smart blades’. A high fidelity Fluid Structure Interaction (FSI) simulation framework is utilized, comprised of 2D Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) models....... A coupled aero-structural simulation of a 10% chordwise length morphing trailing edge flap for a 4 MW wind turbine rotor is carried out and response surfaces are produced with respect to the flap internal geometry design parameters for the design conditions. Surrogate model based optimization is applied...

  16. Numerical Study on Heat Transfer Performance of PCHE With Supercritical CO2 as Working Fluid

    International Nuclear Information System (INIS)

    Jeon, Sang Woo; Ngo, Ich-long; Byon, Chan

    2016-01-01

    The printed circuit heat exchanger (PCHE) is regarded as a promising candidate for advanced heat exchangers for the next-generation supercritical CO 2 power generation owing to its high compactness and rigid structure. In this study, an innovative type of PCHE, in which the channel sizes for the heat source fluid and heat sink fluid are different, is considered for analysis. The thermal performance of the PCHE, with supercritical CO 2 as the working fluid, is numerically analyzed. The results have shown that the thermal performance of the PCHE decreases monotonically when the channel size of either the heat source channel or the heat sink channel, because of the decreased flow velocity. On the other hand, the thermal performance of the PCHE is found to be almost independent of the spacing between the channels. In addition, it was found that the channel cross sectional shape has little effect on the thermal performance when the hydraulic diameter of the channel remains constant.

  17. The thermodynamic cycle models for geothermal power plants by considering the working fluid characteristic

    Science.gov (United States)

    Mulyana, Cukup; Adiprana, Reza; Saad, Aswad H.; M. Ridwan, H.; Muhammad, Fajar

    2016-02-01

    The scarcity of fossil energy accelerates the development of geothermal power plant in Indonesia. The main issue is how to minimize the energy loss from the geothermal working fluid so that the power generated can be increased. In some of geothermal power plant, the hot water which is resulted from flashing is flown to injection well, and steam out from turbine is condensed in condenser, while the temperature and pressure of the working fluid is still high. The aim of this research is how the waste energy can be re-used as energy source to generate electric power. The step of the research is started by studying the characteristics of geothermal fluid out from the well head. The temperature of fluid varies from 140°C - 250°C, the pressure is more than 7 bar and the fluid phase are liquid, gas, or mixing phase. Dry steam power plant is selected for vapor dominated source, single or multiple flash power plant is used for dominated water with temperature > 225°C, while the binary power plant is used for low temperature of fluid enthalpy, the calculated power of these double and triple flash power plant are 50% of W1+W2. At the last step, the steam out from the turbine of unit 3 with the temperature 150°C is used as a heat source for binary cycle power plant named unit 4, while the hot water from the flasher is used as a heat source for the other binary cycle named unit 5 resulted power W5+W6 or 15% of W1+W2. Using this integrated model the power increased 75% from the original one.

  18. Effect of Mixed Working Fluid Composition on Binary Cycle Condenser Heat Transfer Coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Dan Wendt; Greg Mines

    2011-10-01

    Effect of Mixed Working Fluid Composition on Binary Cycle Condenser Heat Transfer Coefficients Dan Wendt, Greg Mines Idaho National Laboratory The use of mixed working fluids in binary power plants can provide significant increases in plant performance, provided the heat exchangers are designed to take advantage of these fluids non-isothermal phase changes. In the 1980's testing was conducted at DOE's Heat Cycle Research Facility (HCRF) where mixtures of different compositions were vaporized at supercritical pressures and then condensed. This testing had focused on using the data collected to verify that Heat Transfer Research Incorporated (HTRI) codes were suitable for the design of heat exchangers that could be used with mixtures. The HCRF data includes mixture compositions varying from 0% to 40% isopentane and condenser tube orientations of 15{sup o}, 60{sup o}, and 90{sup o} from horizontal. Testing was performed over a range of working fluid and cooling fluid conditions. Though the condenser used in this testing was water cooled, the working fluid condensation occurred on the tube-side of the heat exchanger. This tube-side condensation is analogous to that in an air-cooled condenser. Tube-side condensing heat transfer coefficient information gleaned from the HCRF testing is used in this study to assess the suitability of air-cooled condenser designs for use with mixtures. Results of an air-cooled binary plant process model performed with Aspen Plus indicate that that the optimal mixture composition (producing the maximum net power for the scenario considered) is within the range of compositions for which data exist. The HCRF data is used to assess the impact of composition, tube orientation, and process parameters on the condensing heat transfer coefficients. The sensitivity of the condensing coefficients to these factors is evaluated and the suitability of air-cooled condenser designs with mixtures is assessed. This paper summarizes the evaluation

  19. Design and numerical study of turbines operating with MDM as working fluid

    Science.gov (United States)

    Klonowicz, Piotr; Surwiło, Jan; Witanowski, Łukasz; Suchocki, Tomasz K.; Kozanecki, Zbigniew; Lampart, Piotr

    2015-12-01

    Design processes and numerical simulations have been presented for a few cases of turbines designated to work in ORC systems. The chosen working fluid isMDM. The considered design configurations include single stage centripetal reaction and centrifugal impulse turbines as well as multistage axial turbines. The power outputs vary from about 75 kW to 1 MW. The flow in single stage turbines is supersonic and requires special design of blades. The internal efficiencies of these configurations exceed 80% which is considered high for these type of machines. The efficiency of axial turbines exceed 90%. Possible turbine optimization directions have been also outlined in the work.

  20. Working memory and fluid intelligence are both identical to g?! Reanalyses and critical evaluation

    Directory of Open Access Journals (Sweden)

    GILLES E. GIGNAC

    2007-09-01

    Full Text Available In this investigation, two previously published confirmatory factor analytic studies that separately reported working memory and fluid intelligence higher-order loadings so large as to suggest isomor-phism with g were evaluated critically within the context of internal consistency reliability. Specifi-cally, based on two data analytic approaches, the previously reported higher-order loadings which suggested isomorphism with g were demonstrated to have been achieved via the substantial disattenua-tion effects observed within structural equation modeling, when the latent variable corresponding composite scores are associated with low levels of reliability. The two approaches were: (1 the obverse of the disattenuation procedure for imperfect reliability, and (2 the implied correlation between a corresponding phantom composite variable and a higher-order g factor. The results derived from the two approaches were found to correspond very closely. To allow for a more informative evaluation, researchers are encouraged to report the internal consistency reliabilities associated with the composite scores which correspond to their latent variables, as well as to report both the disattenuated and attenu-ated higher-order loadings within their multi-factor models.

  1. A Latent Variable Analysis of Working Memory Capacity, Short-Term Memory Capacity, Processing Speed, and General Fluid Intelligence.

    Science.gov (United States)

    Conway, Andrew R. A.; Cowan, Nelsin; Bunting, Michael F.; Therriault, David J.; Minkoff, Scott R. B.

    2002-01-01

    Studied the interrelationships among general fluid intelligence, short-term memory capacity, working memory capacity, and processing speed in 120 young adults and used structural equation modeling to determine the best predictor of general fluid intelligence. Results suggest that working memory capacity, but not short-term memory capacity or…

  2. An organic group contribution approach to radiative efficiency estimation of organic working fluid

    International Nuclear Information System (INIS)

    Zhang, Xinxin; Kobayashi, Noriyuki; He, Maogang; Wang, Jingfu

    2016-01-01

    Highlights: • We use group contribution method to estimate radiative efficiency. • CFC, HCFC, HFC, HFE, and PFC were estimated using this method. • In most cases, the estimation value has a good precision. • The method is reliable for the estimation of molecule with a symmetric structure. • This estimation method can offer good reference for working fluid development. - Abstract: The ratification of the Montreal Protocol in 1987 and the Kyoto Protocol in 1997 mark an environment protection era of the development of organic working fluid. Ozone depletion potential (ODP) and global warming potential (GWP) are two most important indices for the quantitative comparison of organic working fluid. Nowadays, more and more attention has been paid to GWP. The calculation of GWP is an extremely complicated process which involves interactions between surface and atmosphere such as atmospheric radiative transfer and atmospheric chemical reactions. GWP of a substance is related to its atmospheric abundance and is a variable in itself. However, radiative efficiency is an intermediate parameter for GWP calculation and it is a constant value used to describe inherent property of a substance. In this paper, the group contribution method was adopted to estimate the radiative efficiency of the organic substance which contains more than one carbon atom. In most cases, the estimation value and the standard value are in a good agreement. The biggest estimation error occurs in the estimation of the radiative efficiency of fluorinated ethers due to its plenty of structure groups and its complicated structure compared with hydrocarbon. This estimation method can be used to predict the radiative efficiency of newly developed organic working fluids.

  3. Performance Characteristics of Hero's Turbine Using Hot Water as a Working Fluid

    OpenAIRE

    藤井, 照重; 太田, 淳一; 赤川, 浩爾; 中村, 登志; 浅野, 等

    1990-01-01

    From the view point of energy saving and the development of new energy resources,it is important to utilize geothermal resources and waste heat from factories. As one of the energy conversion expanders,there is a radial outflow reaction turbine(that is,Hero's turbine). Performance characteristics of Hero's turbine using subcooled hot water as a working fluid are clarified analytically and experimentally. It is found that:(a)there is an optimum rotational speed at which maximum turbine efficie...

  4. Evaluation of carbon fiber composites fabricated using ionic liquid based epoxies for cryogenic fluid applications

    Directory of Open Access Journals (Sweden)

    R.N. Grugel

    Full Text Available Utilizing tanks fabricated from fiber reinforced polymeric composites for storing cryogenic fluids such as liquid oxygen and liquid hydrogen is of great interest to NASA as considerable weight savings can be gained. Unfortunately such composites, especially at cryogenic temperatures, develop a mismatch that initiates detrimental delamination and crack growth, which promotes leaking. On-going work with ionic liquid-based epoxies appears promising in mitigating these detrimental effects. Some recent results are presented and discussed. Keywords: Ionic liquid, Carbon fiber, Epoxy, COPV, Cryogenic fluids

  5. The role of fluid pressure on frictional behavior at the base of the seismogenic zone

    Science.gov (United States)

    Hirth, Greg; Beeler, Nicholas M.

    2015-01-01

    To characterize stress and deformation style at the base of the seismogenic zone, we investigate how the mechanical properties of fluid-rock systems respond to variations in temperature and strain rate. The role of fluids on the processes responsible for the brittle-ductile transition in quartz-rich rocks has not been explored at experimental conditions where the kinetic competition between microcracking and viscous flow is similar to that expected in the Earth. Our initial analysis of this competition suggests that the effective stress law for sliding friction should not work as efficiently near the brittle-ductile transition as it does at shallow conditions

  6. Open Loop Heat Pipe Radiator Having a Free-Piston for Wiping Condensed Working Fluid

    Science.gov (United States)

    Weinstein, Leonard M. (Inventor)

    2015-01-01

    An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

  7. Performance Study of Solar Heat Pipe with Different Working Fluids and Fill Ratios

    Science.gov (United States)

    Harikrishnan, S. S.; Kotebavi, Vinod

    2016-09-01

    This paper elaborates on the testing of solar heat pipes using different working fluids, fill ratios and tilt angles. Methanol, Acetone and water are used as working fluids, with fill ratios 25%, 50%, 75% and 100%. Experiments were carried out at 600 and 350 inclinations. Heat pipe condenser section is placed inside a water basin containing 200ml of water. The evaporator section is exposed to sunlight where the working fluid gets heated and it becomes vapour and moves towards the condenser section. In the condenser section the heat is given to the water in the basin and the vapour becomes liquid and comes back to the evaporator section due to gravitational force. Two modes of experiments are carried out: 1) using a parabolic collector and 2) using heat pipe with evacuated tubes. On comparative study, optimum fill ratio is been found to be 25% in every case and acetone exhibited slightly more efficiency than methanol and water. As far as the heat pipe orientation is concerned, 600 inclination of the heat pipe showed better performance than 350

  8. Thermal Characterisation of Micro Flat Aluminium Heat Pipe Arrays by Varying Working Fluid and Inclination Angle

    Directory of Open Access Journals (Sweden)

    Guanghan Huang

    2018-06-01

    Full Text Available A micro heat pipe array is desirable owing to its high heat transfer capacity, compact size, and high surface–volume ratio compared with conventional heat pipes. In this study, micro flat aluminium heat pipe arrays (MF-AHPA were developed and systematically characterised by varying working fluid and inclination angle. Three MF-AHPAs with different working fluids, i.e., acetone, cyclopentane, and n-hexane, were fabricated. The acetone MF-AHPA achieved the best thermal performance. The underlying mechanism is the small flow viscous friction and small shearing force of liquid vapour. Additionally, the experimental results show a strong dependence of MF-AHPAs’ thermal resistance on the orientation due to the gravitational effect on axial liquid distribution. Finally, a criterion is proposed to determine the optimal inclination angle of the MF-AHPA. In the present study, a volumetric fraction (αa,c of 74 ± 7% has been shown to well predict an optimal inclination angle of the MF-AHPAs with various working fluids and heat loads.

  9. Experimental evaluation of a non-azeotropic working fluid for geothermal heat pump system

    International Nuclear Information System (INIS)

    Zhao, L.

    2004-01-01

    Geothermal energy resources are found in many countries. A reasonable and efficient utilization of these resources has been a worldwide concern. The application of geothermal heat pump systems (GHPS) can help increase the efficiency of using geothermal energy and reduce the thermal pollution to the earth surface. However, this is only possible with a proper working fluid. In this paper, a non-azeotropic working fluid (R290/R600a/R123) is presented for a GHPS where geothermal water at 40-45 deg. C and heating network water at 70-80 deg. C serve as the low and high temperature heat sources. Experimental results show that the coefficient of performance (COP) of a GHPS using the working fluid is above 3.5 with the condensation temperature above 80 deg. C and the condensation pressure below 18 bar, while the temperature of the geothermal water is reduced from 40-46 deg. C to 31-36 deg. C

  10. Fluid Dynamic Models for Bhattacharyya-Based Discriminant Analysis.

    Science.gov (United States)

    Noh, Yung-Kyun; Hamm, Jihun; Park, Frank Chongwoo; Zhang, Byoung-Tak; Lee, Daniel D

    2018-01-01

    Classical discriminant analysis attempts to discover a low-dimensional subspace where class label information is maximally preserved under projection. Canonical methods for estimating the subspace optimize an information-theoretic criterion that measures the separation between the class-conditional distributions. Unfortunately, direct optimization of the information-theoretic criteria is generally non-convex and intractable in high-dimensional spaces. In this work, we propose a novel, tractable algorithm for discriminant analysis that considers the class-conditional densities as interacting fluids in the high-dimensional embedding space. We use the Bhattacharyya criterion as a potential function that generates forces between the interacting fluids, and derive a computationally tractable method for finding the low-dimensional subspace that optimally constrains the resulting fluid flow. We show that this model properly reduces to the optimal solution for homoscedastic data as well as for heteroscedastic Gaussian distributions with equal means. We also extend this model to discover optimal filters for discriminating Gaussian processes and provide experimental results and comparisons on a number of datasets.

  11. Relationships among processing speed, working memory, and fluid intelligence in children.

    Science.gov (United States)

    Fry, A F; Hale, S

    2000-10-01

    The present review focuses on three issues, (a) the time course of developmental increases in cognitive abilities; (b) the impact of age on individual differences in these abilities, and (c) the mechanisms by which developmental increases in different aspects of cognition affect each other. We conclude from our review of the literature that the development of processing speed, working memory, and fluid intelligence, all follow a similar time course, suggesting that all three abilities develop in concert. Furthermore, the strength of the correlation between speed and intelligence does not appear to change with age, and most of the effect of the age-related increase in speed on intelligence appears to be mediated through the effect of speed on working memory. Finally, most of the effect of the age-related improvement in working memory on intelligence is itself attributable to the effect of the increase in speed on working memory, providing evidence of a cognitive developmental cascade.

  12. Fluid-based radon mitigation technology development for industrial applications

    International Nuclear Information System (INIS)

    Liu, K.V.; Gabor, J.D.; Holtz, R.E.; Gross, K.C.

    1996-01-01

    The objective of the radon mitigation technology development effort is to develop an efficient and economical radon gas removal technology based on a fluid absorption process. The technology must be capable of cleaning up a wide range of radon gas stream concentrations to a level that meets EPA gas emission standards for residential and industrial applications. Argonne has recently identified a phenomenon that offers the possibility of radon recovery from the atmosphere with high efficiency at room temperature, and radon release at slightly elevated temperatures (50-60 degrees C.) such a device would offer numerous substantial advantages over conventional cryogenic charcoal systems for the removal of radon. Controlled sources of radon in Argonne's radon research facility are being used to quantitatively assess the performance of a selected class of absorbing fluids over a range of radon concentrations. This paper will discuss the design of laboratory- and engineering-scale radon absorption units and present some preliminary experimental test results

  13. Reliable gains? Evidence for substantially underpowered designs in studies of working memory training transfer to fluid intelligence.

    Science.gov (United States)

    Bogg, Tim; Lasecki, Leanne

    2014-01-01

    In recent years, cognitive scientists and commercial interests (e.g., Fit Brains, Lumosity) have focused research attention and financial resources on cognitive tasks, especially working memory tasks, to explore and exploit possible transfer effects to general cognitive abilities, such as fluid intelligence. The increased research attention has produced mixed findings, as well as contention about the disposition of the evidence base. To address this contention, Au et al. (2014) recently conducted a meta-analysis of extant controlled experimental studies of n-back task training transfer effects on measures of fluid intelligence in healthy adults; the results of which showed a small training transfer effect. Using several approaches, the current review evaluated and re-analyzed the meta-analytic data for the presence of two different forms of small-study effects: (1) publication bias in the presence of low power and; (2) low power in the absence of publication bias. The results of these approaches showed no evidence of selection bias in the working memory training literature, but did show evidence of small-study effects related to low power in the absence of publication bias. While the effect size estimate identified by Au et al. (2014) provided the most precise estimate to date, it should be interpreted in the context of a uniformly low-powered base of evidence. The present work concludes with a brief set of considerations for assessing the adequacy of a body of research findings for the application of meta-analytic techniques.

  14. Design of a broadband ultra-large area acoustic cloak based on a fluid medium

    Science.gov (United States)

    Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

    2014-10-01

    A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

  15. Effect of Working Fluids on the Thermal Performance of a Bi-directional Solar Thermodiode

    International Nuclear Information System (INIS)

    Ko, Yung Joo

    2008-02-01

    (Smart Module System) were made. Six kinds of working fluids were used to investigate their effects on the thermal performance of a bi-directional solar thermo diode. Two kinds of thermo diodes were studied. The first one is the mono-directional thermo diode that allows heat flow in the desired direction but blocks in the opposite direction. The second one is the bi-directional thermo diode of which the direction of heat flow, surface absorptivity and heat capacity of the module can be adjusted for maximum energy efficiency. This hi-directional can be used both for the summer cooling and winter heating of buildings and shelters. Usually, the thermo diodes are simple beam shape, but in this study, they were redesigned a s two L-shaped loops mounted between a collector plate and a Storage tank. Rotable joints between the horizontal and inclined segments of the loop enable easy alteration of geat transfer direction. The loops and tank were filled with a working fluid for effective heat transfer when the solar thermo diode was forwarded biased. The solar thermo diode was heated by a radiant heater that consisted of 20 halogen lamps that generates a heat flux of about 1000W/m 2 on the collector surface. The working fluids used in the study were water, acetone, ethylalcohol. In addition, three kinds of silicon oil with different viscosity were studied. And three mixtures of water and ethylalcohol of different volume ratio were used. Finally, the nano fluids were also studied. Working fluids were tested with thermal conductivity values ranging from 0.1 to 0.56 W/m- .deg. C, thermal expansion coefficient values ranging from 1.8 x 10 -4 to 1.3 x 10 -3 K -1 , and kinematic viscosity values ranging from 0.65 x 10 -6 to 100 x 10 -6 m 2 /s. Through the study, it was found that the circulation point(CP) at the onset of fluid flow is very important. for a given working fluid, the heat transfer and heated stability of the system depends strongly on the circulation point of the fluid

  16. Lemna minor tolerance to metal-working fluid residues: implications for rhizoremediation.

    Science.gov (United States)

    Grijalbo, L; Becerril, J M; Barrutia, O; Gutierrez-Mañero, J; Lucas Garcia, J A

    2016-07-01

    For the first time in the literature, duckweed (Lemna minor) tolerance (alone or in combination with a consortium of bacteria) to spent metal-working fluid (MWF) was assessed, together with its capacity to reduce the chemical oxygen demand (COD) of this residue. In a preliminary study, L. minor response to pre-treated MWF residue (ptMWF) and vacuum-distilled MWF water (MWFw) was tested. Plants were able to grow in both residues at different COD levels tested (up to 2300 mg·l(-1) ), showing few toxicity symptoms (mainly growth inhibition). Plant response to MWFw was more regular and dose responsive than when exposed to ptMWF. Moreover, COD reduction was less significant in ptMWF. Thus, based on these preliminary results, a second study was conducted using MWFw to test the effectiveness of inoculation with a bacterial consortium isolated from a membrane bioreactor fed with the same residue. After 5 days of exposure, COD in solutions containing inoculated plants was significantly lower than in non-inoculated ones. Moreover, inoculation reduced β+γ-tocopherol levels in MWFw-exposed plants, suggesting pollutant imposed stress was reduced. We therefore conclude from that L. minor is highly tolerant to spent MWF residues and that this species can be very useful, together with the appropriate bacterial consortium, in reducing COD of this residue under local legislation limits and thus minimise its potential environmental impact. Interestingly, the lipophilic antioxidant tocopherol (especially the sum of β+γ isomers) proved to be an effective plant biomarker of pollution. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  17. Metalworking and machining fluids

    Science.gov (United States)

    Erdemir, Ali; Sykora, Frank; Dorbeck, Mark

    2010-10-12

    Improved boron-based metal working and machining fluids. Boric acid and boron-based additives that, when mixed with certain carrier fluids, such as water, cellulose and/or cellulose derivatives, polyhydric alcohol, polyalkylene glycol, polyvinyl alcohol, starch, dextrin, in solid and/or solvated forms result in improved metalworking and machining of metallic work pieces. Fluids manufactured with boric acid or boron-based additives effectively reduce friction, prevent galling and severe wear problems on cutting and forming tools.

  18. High viscosity fluid simulation using particle-based method

    KAUST Repository

    Chang, Yuanzhang

    2011-03-01

    We present a new particle-based method for high viscosity fluid simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke\\'s law, is included in the traditional Navier-Stokes equation to simulate the movements of the high viscosity fluids. Benefiting from the Lagrangian nature of Smoothed Particle Hydrodynamics method, large flow deformation can be well handled easily and naturally. In addition, in order to eliminate the particle deficiency problem near the boundary, ghost particles are employed to enforce the solid boundary condition. Compared with Finite Element Methods with complicated and time-consuming remeshing operations, our method is much more straightforward to implement. Moreover, our method doesn\\'t need to store and compare to an initial rest state. The experimental results show that the proposed method is effective and efficient to handle the movements of highly viscous flows, and a large variety of different kinds of fluid behaviors can be well simulated by adjusting just one parameter. © 2011 IEEE.

  19. Numerical Comparison of NASA's Dual Brayton Power Generation System Performance Using CO2 or N2 as the Working Fluid

    Science.gov (United States)

    Ownens, Albert K.; Lavelle, Thomas M.; Hervol, David S.

    2010-01-01

    A Dual Brayton Power Conversion System (DBPCS) has been tested at the NASA Glenn Research Center using Nitrogen (N2) as the working fluid. This system uses two closed Brayton cycle systems that share a common heat source and working fluid but are otherwise independent. This system has been modeled using the Numerical Propulsion System Simulation (NPSS) environment. This paper presents the results of a numerical study that investigated system performance changes resulting when the working fluid is changed from gaseous (N2) to gaseous carbon dioxide (CO2).

  20. Selection and optimization of pure and mixed working fluids for low grade heat utilization using organic Rankine cycles

    DEFF Research Database (Denmark)

    Andreasen, Jesper Graa; Larsen, Ulrik; Knudsen, Thomas

    2014-01-01

    We present a generic methodology for organic Rankine cycle optimization, where the working fluid is included as an optimization parameter, in order to maximize the net power output of the cycle. The method is applied on two optimization cases with hot fluid inlet temperatures at 120°C and 90°C. P...

  1. Working memory capacity and fluid abilities: the more difficult the item, the more more is better.

    Science.gov (United States)

    Little, Daniel R; Lewandowsky, Stephan; Craig, Stewart

    2014-01-01

    The relationship between fluid intelligence and working memory is of fundamental importance to understanding how capacity-limited structures such as working memory interact with inference abilities to determine intelligent behavior. Recent evidence has suggested that the relationship between a fluid abilities test, Raven's Progressive Matrices, and working memory capacity (WMC) may be invariant across difficulty levels of the Raven's items. We show that this invariance can only be observed if the overall correlation between Raven's and WMC is low. Simulations of Raven's performance revealed that as the overall correlation between Raven's and WMC increases, the item-wise point bi-serial correlations involving WMC are no longer constant but increase considerably with item difficulty. The simulation results were confirmed by two studies that used a composite measure of WMC, which yielded a higher correlation between WMC and Raven's than reported in previous studies. As expected, with the higher overall correlation, there was a significant positive relationship between Raven's item difficulty and the extent of the item-wise correlation with WMC.

  2. Working memory capacity and fluid abilities: The more difficult the item, the more more is better

    Directory of Open Access Journals (Sweden)

    Daniel R Little

    2014-03-01

    Full Text Available The relationship between fluid intelligence and working memory is of fundamental importance to understanding how capacity-limited structures such as working memory interact with inference abilities to determine intelligent behaviour. Recent evidence has suggested that the relationship between a fluid abilities test, Raven's Progressive Matrices, and working memory capacity (WMC may be invariant across difficulty levels of the Raven's items. We show that this invariance can only be observed if the overall correlation between Raven's and WMC is low. Simulations of Raven's performance revealed that as the overall correlation between Raven's and WMC increases, the item-wise point bi-serial correlations involving WMC are no longer constant but increase considerably with item difficulty. The simulation results were confirmed by two studies that used a composite measure of WMC, which yielded a higher correlation between WMC and Raven's than reported in previous studies. As expected, with the higher overall correlation, there was a signifi□cant positive relationship between Raven's item difficulty and the extent of the item-wise correlation with WMC.

  3. FLUOROETHERS AS A WORKING FLUIDS FOR LOW TEMPERATURE ORGANIC RANKINE CYCLE

    Directory of Open Access Journals (Sweden)

    Artemenko S.V

    2014-12-01

    Full Text Available Hydrofluoroethers as a new class of working fluids for the organic Rankine cycle have been considered to utilize the low-potential waste heat. Temperature range 300…400 K was chosen to provide energy conversion of waste heat from fuel cells. The direct assessment of the efficiency criteria for the Rankine cycle via artificial neural networks (ANN was used. To create ANN the critical parameters of substance and normal boiling temperature as input were chosen. The forecast of efficiency criteria for the Rankine cycle as output parameter which reproduces the coefficient of performance with high accuracy and without thermodynamic property calculations was presented.

  4. Experimental Comparison Of Working Fluids For Organic Rankine Cycle With Single-Screw Expander

    OpenAIRE

    Gusev, Sergei; Ziviani, Davide; Bell, Ian; De Paepe, Michel; van den Broek, Martijn

    2014-01-01

    This paper describes the behavior of an Organic Rankine Cycle (ORC) fed by a heat source with adaptable temperature and mass flow. For a suitable choice of working fluid, the setting of its evaporation pressure is crucial for the performance of an ORC installation. The higher the evaporation pressure, the higher the cycle efficiency on the one hand, but the lower the energy recovered from the heat source due to a higher outlet temperature on the other hand. An optimum has to be found to achie...

  5. Morphing-Based Shape Optimization in Computational Fluid Dynamics

    Science.gov (United States)

    Rousseau, Yannick; Men'Shov, Igor; Nakamura, Yoshiaki

    In this paper, a Morphing-based Shape Optimization (MbSO) technique is presented for solving Optimum-Shape Design (OSD) problems in Computational Fluid Dynamics (CFD). The proposed method couples Free-Form Deformation (FFD) and Evolutionary Computation, and, as its name suggests, relies on the morphing of shape and computational domain, rather than direct shape parameterization. Advantages of the FFD approach compared to traditional parameterization are first discussed. Then, examples of shape and grid deformations by FFD are presented. Finally, the MbSO approach is illustrated and applied through an example: the design of an airfoil for a future Mars exploration airplane.

  6. Performance analyses of geothermal organic Rankine cycles with selected hydrocarbon working fluids

    International Nuclear Information System (INIS)

    Liu, Qiang; Duan, Yuanyuan; Yang, Zhen

    2013-01-01

    ORC (organic Rankine cycles) are promising systems for conversion of low temperature geothermal energy to electricity. The thermodynamic performance of the ORC with a wet cooling system is analyzed here using hydrocarbon working fluids driven by geothermal water from 100 °C to 150 °C and reinjection temperatures not less than 70 °C. The hydrocarbon working fluids are butane (R600), isobutane (R600a), pentane (R601), isopentane (R601a) and hexane. For each fluid, the ORC net power output first increases and then decreases with increasing turbine inlet temperature. The turbine inlet parameters are then optimized for the maximum power output. The ORC net power output increases as the condensation temperature decreases but the circulating pump power consumption increases especially for lower condensation temperatures at higher cooling water flow rates. The optimal condensation temperatures for the maximum plant power output are 29.45–29.75 °C for a cooling water inlet temperature of 20 °C and a pinch point temperature difference of 5 °C in the condenser. The maximum power is produced by an ORC using R600a at geothermal water inlet temperatures higher than 120 °C, followed by R245fa and R600 for reinjection temperatures not less than 70 °C. R600a also has the highest plant exergetic efficiency with the lowest turbine size factor. - Highlights: • ORC (organic Rankine cycles) using geothermal water from 100 to 150 °C and reinjection temperatures not less than 70 °C are analyzed. • Condensation temperatures optimized to maximize the plant power output. • An IHE (internal heat exchanger) gives higher plant power at low geothermal water temperatures and high reinjection temperatures. • ORC performance optimized considering the condensation and reinjection temperature. • R600a gives the best performance at the optimal turbine operating parameters

  7. Tailoring peritoneal dialysis fluid for optimal acid-base targets.

    Science.gov (United States)

    Feriani, Mariano

    2009-01-01

    Mild derangements of acid-base status are common features in peritoneal dialysis patients, metabolic acidosis being the most frequent alteration. One of the main tasks of dialysis is to correct these derangements and the target is the normalization of the acid-base parameters since they affect several organs and functions. Since factors affecting acid-base homeostasis are intrinsic characteristics of the individual patient (metabolic acid production, distribution space for bicarbonate, dialytic prescription, etc.), it is not surprising that only relatively few patients achieve the normal range. Only a certain modulation of buffer infusion by using different buffer concentrations in the dialysis fluid may ensure a good correction in a large percentage of patients.

  8. Screening of hydrocarbons as supercritical ORCs working fluids by thermal stability

    International Nuclear Information System (INIS)

    Dai, Xiaoye; Shi, Lin; An, Qingsong; Qian, Weizhong

    2016-01-01

    Highlights: • A rapid evaluation method for thermal stability of hydrocarbons for ORCs. • Methane and hydrogen are confirmed to be decomposition indicators. • The decomposition temperatures for some hydrocarbons using the rapid method. • Long carbon chain hydrocarbons are not suitable for supercritical ORCs. - Abstract: Organic Rankine Cycle (ORC) systems are widely used for industrial waste heat recovery and renewable energy utilization. The supercritical ORC is currently one of the main development directions due to its low exergy loss, high thermal efficiency and high work output. The thermal stability is the major limitation of organic working fluid selection with high temperature heat sources. This paper presents a rapid experimental method for assessing the thermal stability of hydrocarbons for ORCs. The fluids were tested in a high temperature reactor with methane and hydrogen theoretically and experimentally confirmed to be the indicators of thermal decomposition. The thermal decomposition temperatures were obtained for n-hexane, n-pentane, isopentane, cyclopentane, n-butane and isobutane using the rapid experimental method. The results show that cycloalkanes are not the good choices by thermal stability and long carbon chain hydrocarbons (longer than C6) are not suitable for supercritical ORCs due to the thermal stability limitation.

  9. Binary blend of carbon dioxide and fluoro ethane as working fluid in transcritical heat pump systems

    Directory of Open Access Journals (Sweden)

    Zhang Xian-Ping

    2015-01-01

    Full Text Available As an eco-friendly working fluid, carbon dioxide or R744 is expected to substitute for the existing working fluids used in heat pump systems. It is, however, challenged by the much higher heat rejection pressure in transcritical cycle compared with the traditional subcritical cycle using freons. There exists a worldwide tendency to utilize blend refrigerants as alternatives. Therefore, a new binary blend R744/R161 in this research is proposed in order to decrease the heat rejection pressure. Meanwhile, on mixing R744 with R161, the flammability and explosivity of R161 can be suppressed because of the extinguishing effect of R744. A transcritical thermodynamic model is developed, and then the system performances of heat pump using R744/R161 blend are investigated and compared with those of pure R744 system under the same operation conditions. The variations of heat rejection pressure, heating coefficient of performance, unit volumetric heating capacity, discharge temperature of compressor and the mass fraction of R744/R161 are researched. The results show that R744/R161 mixture can reduce the heat rejection pressure of transcritical heat pump system.

  10. Feasibility study for application of mixture working fluid cycle to nuclear reactor power plant

    International Nuclear Information System (INIS)

    Takeuchi, Yutaka; Ohshima, Iwao; Shiomi, Hirozo; Miyamae, Nobuhiko; Hiramatsu, Miki; Montani, Mitsuto

    1999-01-01

    There exists a large amount of unused energy in nuclear power plants. However, it consists of relatively low temperature energy, so it is difficult to generate electricity by the conventional water-steam cycle. In order to utilize such low temperature energy, we applied a mixture working fluid cycle called as the Kalina cycle to a light water nuclear reactor power plant. The Kalina cycle uses a working fluid composed of ammonia and water to create a variable temperature boiling process. We applied a saturation type Kalina cycle with single stage ammonia-water separation process as a bottoming cycle to a conventional water-steam cycle of a 1100MWe class BWR as an example case. The input heat source is the exhaust or the partial extraction of a low pressure turbine (LPT). A steady state chemical process modeling code ASPENPLUS was used for the sensitivity analyses. The maximum efficiency was calculated to be realized when using the lowest heat sink temperature, 8degC. The additional electrical output is about 95 MWe when using the exhaust of LPT and is about 127 MWe when using the partial extraction of LPT. Namely, about 4.3% of the exhaust heat for the former case and about 5.8% for the latter case can be utilized as electrical power, respectively. (author)

  11. Fluid Analysis and Improved Structure of an ATEG Heat Exchanger Based on Computational Fluid Dynamics

    Science.gov (United States)

    Tang, Z. B.; Deng, Y. D.; Su, C. Q.; Yuan, X. H.

    2015-06-01

    In this study, a numerical model has been employed to analyze the internal flow field distribution in a heat exchanger applied for an automotive thermoelectric generator based on computational fluid dynamics. The model simulates the influence of factors relevant to the heat exchanger, including the automotive waste heat mass flow velocity, temperature, internal fins, and back pressure. The result is in good agreement with experimental test data. Sensitivity analysis of the inlet parameters shows that increase of the exhaust velocity, compared with the inlet temperature, makes little contribution (0.1 versus 0.19) to the heat transfer but results in a detrimental back pressure increase (0.69 versus 0.21). A configuration equipped with internal fins is proved to offer better thermal performance compared with that without fins. Finally, based on an attempt to improve the internal flow field, a more rational structure is obtained, offering a more homogeneous temperature distribution, higher average heat transfer coefficient, and lower back pressure.

  12. Preparations and properties of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials.

    Science.gov (United States)

    Watanabe, Shoji

    2008-01-01

    This short review describes various types of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials. It is concerned with synthetic additives classified according to their functional groups; silicone compounds, carboxylic acids and dibasic acids, esters, Diels-Alder adducts, various polymers, nitrogen compounds, phosphoric esters, phosphonic acids, and others. Testing methods for water-soluble metal working fluids for aluminum alloy materials are described for a practical application in a laboratory.

  13. Potential performance improvement using a reacting gas (nitrogin tetroxide) as the working fluid in a closed Brayton cycle

    Science.gov (United States)

    Stochl, R. J.

    1979-01-01

    The results of an analysis to estimate the performance that could be obtained by using a chemically reacting gas (nitrogen tetroxide) as the working fluid in a closed Brayton cycle are presented. Compared with data for helium as the working fluid, these results indicate efficiency improvements from 4 to 90 percent, depending on turbine inlet temperature, pressures, and gas residence time in heat transfer equipment.

  14. Offshore disposal of oil-based drilling fluid waste

    International Nuclear Information System (INIS)

    Malachosky, E.; Shannon, B.E.; Jackson, J.E.

    1991-01-01

    Offshore drilling operations in the Gulf of Mexico may use oil-based drilling fluids to mitigate drilling problems. The result is the generation of a significant quantity of oily cuttings and mud. The transportation of this waste for onshore disposal is a concern from a standpoint of both personnel safety and potential environmental impact. A process for preparing a slurry of this waste and the subsequent disposal of the slurry through annular pumping has been put into use by ARCO Oil and Gas Company. The disposal technique has been approved by the Minerals Management Service (MMS). The slurried waste is displaced down a casing annulus into a permeable zone at a depth below the surface casing setting depth. The annular disposal includes all cuttings and waste oil mud generated during drilling with oil-based fluids. This disposal technique negates the need for cuttings storage on the platform, transportation to shore, and the environmental effects of onshore surface disposal. The paper describes the environmental and safety concerns with onshore disposal, the benefits of annular disposal, and the equipment and process used for the preparation and pumping of the slurry

  15. Water and clay based drilling fluids for oil wells; Fluidos hidroargilosos para perfuracao de pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, R.C.A. de; Amorim, L.V.; Santana, L.N. de L. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)], e-mail: nalealves@hotmail.com

    2008-07-01

    In the onshore drilling of wells are commonly used aqueous fluids containing bentonite clays. However, to perform their functions generally there is the necessity of additives to drilling fluids, like viscositying, filtered reducer and lubricant. Thus, this work aims to develop water and clay base drilling fluids with low solid text, and with polymeric and lubricants additives. Were studied a sample of industrialized sodium bentonite clays, three polymeric compounds in the ternary form and a sample of lubricant, in different concentrations. Were determined the flow curves, the apparent and plastic viscosities, the yield limit and gel force in Fann 35A viscometer, the filtered volume in API filter-press and the lubricity coefficient in Ofite lubricimeter. The results showed that the fluid had pseudoplastic behavior, the polymeric additives adjusts their rheological properties and filtration and the addition of 1% of lubricant is sufficient to improve the lubricity of fluids. (author)

  16. Integrated working fluid-thermodynamic cycle design of organic Rankine cycle power systems for waste heat recovery

    DEFF Research Database (Denmark)

    Cignitti, Stefano; Andreasen, Jesper Graa; Haglind, Fredrik

    2017-01-01

    recovery. Inthis paper, an organic Rankine cycle process and its pure working fluid are designed simultaneously forwaste heat recovery of the exhaust gas from a marine diesel engine. This approach can overcome designissues caused by the high sensitivity between the fluid and cycle design variables......Today, some established working fluids are being phased out due to new international regulations on theuse of environmentally harmful substances. With an ever-increasing cost to resources, industry wants toconverge on improved sustainability through resource recovery, and in particular waste heat...

  17. Study on Mixed Working Fluids with Different Compositions in Organic Rankine Cycle (ORC Systems for Vehicle Diesel Engines

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2014-08-01

    Full Text Available One way to increase the thermal efficiency of vehicle diesel engines is to recover waste heat by using an organic Rankine cycle (ORC system. Tests were conducted to study the running performances of diesel engines in the whole operating range. The law of variation of the exhaust energy rate under various engine operating conditions was also analyzed. A diesel engine-ORC combined system was designed, and relevant evaluation indexes proposed. The variation of the running performances of the combined system under various engine operating conditions was investigated. R245fa and R152a were selected as the components of the mixed working fluid. Thereafter, six kinds of mixed working fluids with different compositions were presented. The effects of mixed working fluids with different compositions on the running performances of the combined system were revealed. Results show that the running performances of the combined system can be improved effectively when mass fraction R152a in the mixed working fluid is high and the engine operates with high power. For the mixed working fluid M1 (R245fa/R152a, 0.1/0.9, by mass fraction, the net power output of the combined system reaches the maximum of 34.61 kW. Output energy density of working fluid (OEDWF, waste heat recovery efficiency (WHRE, and engine thermal efficiency increasing ratio (ETEIR all reach their maximum values at 42.7 kJ/kg, 10.90%, and 11.29%, respectively.

  18. Acoustic Velocity and Attenuation in Magnetorhelogical fluids based on an effective density fluid model

    Directory of Open Access Journals (Sweden)

    Shen Min

    2016-01-01

    Full Text Available Magnetrohelogical fluids (MRFs represent a class of smart materials whose rheological properties change in response to the magnetic field, which resulting in the drastic change of the acoustic impedance. This paper presents an acoustic propagation model that approximates a fluid-saturated porous medium as a fluid with a bulk modulus and effective density (EDFM to study the acoustic propagation in the MRF materials under magnetic field. The effective density fluid model derived from the Biot’s theory. Some minor changes to the theory had to be applied, modeling both fluid-like and solid-like state of the MRF material. The attenuation and velocity variation of the MRF are numerical calculated. The calculated results show that for the MRF material the attenuation and velocity predicted with this effective density fluid model are close agreement with the previous predictions by Biot’s theory. We demonstrate that for the MRF material acoustic prediction the effective density fluid model is an accurate alternative to full Biot’s theory and is much simpler to implement.

  19. Experimental analysis to improving thermosyphon (TPCT) thermal efficiency using nanoparticles/based fluids (water)

    Science.gov (United States)

    Hoseinzadeh, S.; Sahebi, S. A. R.; Ghasemiasl, R.; Majidian, A. R.

    2017-05-01

    In the present study an experimental set-up is used to investigate the effect of a nanofluid as a working fluid to increase thermosyphon efficiency. Nanofluids are a new form of heat transfer media prepared by suspending metallic and nonmetallic nanoparticles in a base fluid. The nanoparticles added to the fluid enhance the thermal characteristics of the base fluid. The nanofluid used in this experiment was a mixture of water and nanoparticles prepared with 0.5%, 1%, 1.5%, or 2% (v) concentration of silicon carbide (SiC) nanoparticles and 1%, 2% and 3% (v) concentration of aluminum oxide (Al2O3) in an ultrasonic homogenizer. The results indicate that the SiC/water and Al2O3/water nanofluids increase the thermosyphon performance. The efficiency of the thermosyphon using the 2% (v) (SiC) nanoparticles nanofluid was 1.11 times that of pure water and the highest efficiency occurs for the 3% (Al2O3) nanoparticle concentration with input power of 300 W. The decrease in the temperature difference between the condenser and evaporator confirms these enhancements.

  20. Fluid model of inductively coupled plasma etcher based on COMSOL

    International Nuclear Information System (INIS)

    Cheng Jia; Ji Linhong; Zhu Yu; Shi Yixiang

    2010-01-01

    Fluid dynamic models are generally appropriate for the investigation of inductively coupled plasmas. A commercial ICP etcher filled with argon plasma is simulated in this study. The simulation is based on a multiphysical software, COMSOL(TM), which is a partial differential equation solver. Just as with other plasma fluid models, there are drift-diffusion approximations for ions, the quasi-neutrality assumption for electrons movements, reduced Maxwell equations for electromagnetic fields, electron energy equations for electron temperatures and the Navier-Stokes equation for neutral background gas. The two-dimensional distribution of plasma parameters are shown at 200 W of power and 1.33 Pa (10 mTorr) of pressure. Then the profile comparison of the electron number density and temperature with respect to power is illustrated. Finally we believe that there might be some disagreement between the predicted values and the real ones, and the reasons for this difference would be the Maxwellian eedf assumption and the lack of the cross sections of collisions and the reaction rates. (semiconductor physics)

  1. Working memory - not processing speed - mediates fluid intelligence deficits associated with attention deficit/hyperactivity disorder symptoms.

    Science.gov (United States)

    Brydges, Christopher R; Ozolnieks, Krista L; Roberts, Gareth

    2017-09-01

    Attention deficit/hyperactivity disorder (ADHD) is a psychological condition characterized by inattention and hyperactivity. Cognitive deficits are commonly observed in ADHD patients, including impaired working memory, processing speed, and fluid intelligence, the three of which are theorized to be closely associated with one another. In this study, we aimed to determine if decreased fluid intelligence was associated with ADHD, and was mediated by deficits in working memory and processing speed. This study tested 142 young adults from the general population on a range of working memory, processing speed, and fluid intelligence tasks, and an ADHD self-report symptoms questionnaire. Results showed that total and hyperactive ADHD symptoms correlated significantly and negatively with fluid intelligence, but this association was fully mediated by working memory. However, inattentive symptoms were not associated with fluid intelligence. Additionally, processing speed was not associated with ADHD symptoms at all, and was not uniquely predictive of fluid intelligence. The results provide implications for working memory training programs for ADHD patients, and highlight potential differences between the neuropsychological profiles of ADHD subtypes. © 2015 The British Psychological Society.

  2. A general framework to select working fluid and configuration of ORCs for low-to-medium temperature heat sources

    International Nuclear Information System (INIS)

    Vivian, Jacopo; Manente, Giovanni; Lazzaretto, Andrea

    2015-01-01

    Highlights: • General guidelines are proposed to select ORC working fluid and cycle layout. • Distance between critical and heat source temperature for optimal fluid selection. • Separate contributions of cycle efficiency and heat recovery factor. - Abstract: The selection of the most suitable working fluid and cycle configuration for a given heat source is a fundamental step in the search for the optimum design of Organic Rankine Cycles. In this phase cycle efficiency and heat source recovery factor lead to opposite design choices in the achievement of maximum system efficiency and, in turn, maximum power output. In this work, both separate and combined effects of these two performance factors are considered to supply a thorough understanding of the compromise resulting in maximum performance. This goal is pursued by carrying out design optimizations of four different ORC configurations operating with twenty-seven working fluids and recovering heat from sensible heat sources in the temperature range 120–180 °C. Optimum working fluids and thermodynamic parameters are those which simultaneously allow high cycle efficiency and high heat recovery from the heat source to be obtained. General guidelines are suggested to reach this target for any system configuration. The distance between fluid critical temperature and inlet temperature of the heat source is found to play a key role in predicting the optimum performance of all system configurations regardless of the inlet temperature of the heat source

  3. Working research codes into fluid dynamics education: a science gateway approach

    Science.gov (United States)

    Mason, Lachlan; Hetherington, James; O'Reilly, Martin; Yong, May; Jersakova, Radka; Grieve, Stuart; Perez-Suarez, David; Klapaukh, Roman; Craster, Richard V.; Matar, Omar K.

    2017-11-01

    Research codes are effective for illustrating complex concepts in educational fluid dynamics courses, compared to textbook examples, an interactive three-dimensional visualisation can bring a problem to life! Various barriers, however, prevent the adoption of research codes in teaching: codes are typically created for highly-specific `once-off' calculations and, as such, have no user interface and a steep learning curve. Moreover, a code may require access to high-performance computing resources that are not readily available in the classroom. This project allows academics to rapidly work research codes into their teaching via a minimalist `science gateway' framework. The gateway is a simple, yet flexible, web interface allowing students to construct and run simulations, as well as view and share their output. Behind the scenes, the common operations of job configuration, submission, monitoring and post-processing are customisable at the level of shell scripting. In this talk, we demonstrate the creation of an example teaching gateway connected to the Code BLUE fluid dynamics software. Student simulations can be run via a third-party cloud computing provider or a local high-performance cluster. EPSRC, UK, MEMPHIS program Grant (EP/K003976/1), RAEng Research Chair (OKM).

  4. Advanced working fluids: Thermodynamic properties. Final report, 1 December 1987-30 November 1989

    Energy Technology Data Exchange (ETDEWEB)

    Lee, L.L.; Gering, K.L.

    1990-09-01

    Electrolytes are used as working fluids in gas-fired heat pump-chiller engine cycles. To find out which molecular parameters of the electrolytes impact on cycle performance, a molecular theory, the EXP-MSA correlation, is developed for calculating solution properties, enthalpies, vapor-liquid equilibria, and engine cycle performance. Aqueous and ammoniac single and mixed salt solutions in single and multisolvent systems are investigated. The outcomes are: (1) an accurate correlation is developed to evaluate properties for concentrated electrolyte solutions (e.g., for aqueous LiBr to 19 molal); (2) sensitivity analysis is used to determine the impact of molecular parameters on the thermodynamic properties and cycle performance. The preferred electrolytes are of 1-1 valence type, small ion size, high molecular weight, and in a strongly colligative cosolvent; (3) the abilities of correlation on single-effect and double-effect engine cycles are demonstrated; (4) the operating windows are determined for a number of absorption fluids of industrial importance.

  5. Reliable gains? Evidence for substantially underpowered designs in studies of working memory training transfer to fluid intelligence

    Directory of Open Access Journals (Sweden)

    Tim eBogg

    2015-01-01

    Full Text Available In recent years, cognitive scientists and commercial interests (e.g., Fit Brains, Lumosity have focused research attention and financial resources on cognitive tasks, especially working memory tasks, to explore and exploit possible transfer effects to general cognitive abilities, such as fluid intelligence. The increased research attention has produced mixed findings, as well as contention about the disposition of the evidence base. To address this contention, J. Au and colleagues (2014; doi:10.3758/s13423-014-0699-x recently conducted a meta-analysis of extant controlled experimental studies of n-back task training transfer effects on measures of fluid intelligence in healthy adults; the results of which showed a small training transfer effect. Using several approaches, the current review evaluated and re-analyzed the meta-analytic data for the presence of two different forms of small-study effects: 1 publication bias in the presence of low power and; 2 low power in the absence of publication bias. The results of these approaches showed no evidence of selection bias in the working memory training literature, but did show evidence of small-study effects related to low power in the absence of publication bias. While the effect size estimate identified by Au and colleagues provided the most precise estimate to date, it should be interpreted in the context of a uniformly low-powered base of evidence. The present work concludes with a brief set of considerations for assessing the adequacy of a body of research findings for the application of meta-analytic techniques.

  6. [Present status and trend of heart fluid mechanics research based on medical image analysis].

    Science.gov (United States)

    Gan, Jianhong; Yin, Lixue; Xie, Shenghua; Li, Wenhua; Lu, Jing; Luo, Anguo

    2014-06-01

    With introduction of current main methods for heart fluid mechanics researches, we studied the characteristics and weakness for three primary analysis methods based on magnetic resonance imaging, color Doppler ultrasound and grayscale ultrasound image, respectively. It is pointed out that particle image velocity (PIV), speckle tracking and block match have the same nature, and three algorithms all adopt block correlation. The further analysis shows that, with the development of information technology and sensor, the research for cardiac function and fluid mechanics will focus on energy transfer process of heart fluid, characteristics of Chamber wall related to blood fluid and Fluid-structure interaction in the future heart fluid mechanics fields.

  7. Fluid mechanics of human fetal right ventricles from image-based computational fluid dynamics using 4D clinical ultrasound scans.

    Science.gov (United States)

    Wiputra, Hadi; Lai, Chang Quan; Lim, Guat Ling; Heng, Joel Jia Wei; Guo, Lan; Soomar, Sanah Merchant; Leo, Hwa Liang; Biwas, Arijit; Mattar, Citra Nurfarah Zaini; Yap, Choon Hwai

    2016-12-01

    There are 0.6-1.9% of US children who were born with congenital heart malformations. Clinical and animal studies suggest that abnormal blood flow forces might play a role in causing these malformation, highlighting the importance of understanding the fetal cardiovascular fluid mechanics. We performed computational fluid dynamics simulations of the right ventricles, based on four-dimensional ultrasound scans of three 20-wk-old normal human fetuses, to characterize their flow and energy dynamics. Peak intraventricular pressure gradients were found to be 0.2-0.9 mmHg during systole, and 0.1-0.2 mmHg during diastole. Diastolic wall shear stresses were found to be around 1 Pa, which could elevate to 2-4 Pa during systole in the outflow tract. Fetal right ventricles have complex flow patterns featuring two interacting diastolic vortex rings, formed during diastolic E wave and A wave. These rings persisted through the end of systole and elevated wall shear stresses in their proximity. They were observed to conserve ∼25.0% of peak diastolic kinetic energy to be carried over into the subsequent systole. However, this carried-over kinetic energy did not significantly alter the work done by the heart for ejection. Thus, while diastolic vortexes played a significant role in determining spatial patterns and magnitudes of diastolic wall shear stresses, they did not have significant influence on systolic ejection. Our results can serve as a baseline for future comparison with diseased hearts. Copyright © 2016 the American Physiological Society.

  8. Personal Computer (PC) based image processing applied to fluid mechanics

    Science.gov (United States)

    Cho, Y.-C.; Mclachlan, B. G.

    1987-01-01

    A PC based image processing system was employed to determine the instantaneous velocity field of a two-dimensional unsteady flow. The flow was visualized using a suspension of seeding particles in water, and a laser sheet for illumination. With a finite time exposure, the particle motion was captured on a photograph as a pattern of streaks. The streak pattern was digitized and processed using various imaging operations, including contrast manipulation, noise cleaning, filtering, statistical differencing, and thresholding. Information concerning the velocity was extracted from the enhanced image by measuring the length and orientation of the individual streaks. The fluid velocities deduced from the randomly distributed particle streaks were interpolated to obtain velocities at uniform grid points. For the interpolation a simple convolution technique with an adaptive Gaussian window was used. The results are compared with a numerical prediction by a Navier-Stokes computation.

  9. Propositions for a PDF model based on fluid particle acceleration

    International Nuclear Information System (INIS)

    Minier, J.P.; Pozorski, J.

    1997-05-01

    This paper describes theoretical propositions to model the acceleration of a fluid particle in a turbulent flow. Such a model is useful for the PDF approach to turbulent reactive flows as well as for the Lagrangian modelling of two-phase flows. The model developed here draws from ideas already put forward by Sawford but which are generalized to the case of non-homogeneous flows. The model is built so as to revert continuously to Pope's model, which uses a Langevin equation for particle velocities, when the Reynolds number becomes very high. The derivation is based on the technique of fast variable elimination. This technique allow a careful analysis of the relations between different levels of modelling. It also allows to address certain problems in a more rigorous way. In particular, application of this technique shows that models presently used can in principle simulate bubbly flows including the pressure-gradient and added-mass forces. (author)

  10. Molecular simulation studies on thermophysical properties with application to working fluids

    CERN Document Server

    Raabe, Gabriele

    2017-01-01

    This book discusses the fundamentals of molecular simulation, starting with the basics of statistical mechanics and providing introductions to Monte Carlo and molecular dynamics simulation techniques. It also offers an overview of force-field models for molecular simulations and their parameterization, with a discussion of specific aspects. The book then summarizes the available know-how for analyzing molecular simulation outputs to derive information on thermophysical and structural properties. Both the force-field modeling and the analysis of simulation outputs are illustrated by various examples. Simulation studies on recently introduced HFO compounds as working fluids for different technical applications demonstrate the value of molecular simulations in providing predictions for poorly understood compounds and gaining a molecular-level understanding of their properties. This book will prove a valuable resource to researchers and students alike.

  11. Working fluid selection for the Organic Rankine Cycle (ORC) exhaust heat recovery of an internal combustion engine power plant

    Science.gov (United States)

    Douvartzides, S.; Karmalis, I.

    2016-11-01

    Organic Rankine cycle technology is capable to efficiently convert low-grade heat into useful mechanical power. In the present investigation such a cycle is used for the recovery of heat from the exhaust gases of a four stroke V18 MAN 51/60DF internal combustion engine power plant operating with natural gas. Design is focused on the selection of the appropriate working fluid of the Rankine cycle in terms of thermodynamic, environmental and safety criteria. 37 candidate fluids have been considered and all Rankine cycles examined were subcritical. The thermodynamic analysis of all fluids has been comparatively undertaken and the effect of key operation conditions such as the evaporation pressure and the superheating temperature was taken into account. By appropriately selecting the working fluid and the Rankine cycle operation conditions the overall plant efficiency was improved by 5.52% and fuel consumption was reduced by 12.69%.

  12. Preparation and Characterization of Water-Based Nano-fluids for Nuclear Applications

    International Nuclear Information System (INIS)

    Williams, W.C.; Forrest, E.; Hu, L.W.; Buongiorno, J.

    2006-01-01

    As part of an effort to evaluate water-based nano-fluids for nuclear applications, preparation and characterization has been performed for nano-fluids being considered for MIT's nano-fluid heat transfer experiments. Three methods of generating these nano-fluids are available: creating them from chemical precipitation, purchasing the nano-particles in powder form and mixing them with the base fluid, and direct purchase of prepared nano-fluids. Characterization of nano-fluids includes colloidal stability, size distribution, concentration, and elemental composition. Quality control of the nano-fluids to be used for heat transfer testing is crucial; an exact knowledge of the fluid constituents is essential to uncovering mechanisms responsible for heat transport enhancement. Testing indicates that nano-fluids created by mixing a liquid with nano-particles in powder form are often not stable, although some degree of stabilization is obtainable with pH control and/or surfactant addition. Some commercially available prepared nano-fluids have been found to contain unacceptable levels of impurities and/or include a different weight percent of nano-particles compared to vendor specifications. Tools utilized to characterize and qualify nano-fluids for this study include neutron activation analysis (NAA), inductively-coupled plasma spectroscopy (ICP), transmission electron microscopy (TEM) imaging, thermogravimetric analysis (TGA) and dynamic light scattering (DLS). Preparation procedures and characterization results for selected nano-fluids will be discussed in detail. (authors)

  13. Impact of the amount of working fluid in loop heat pipe to remove waste heat from electronic component

    Directory of Open Access Journals (Sweden)

    Smitka Martin

    2014-03-01

    Full Text Available One of the options on how to remove waste heat from electronic components is using loop heat pipe. The loop heat pipe (LHP is a two-phase device with high effective thermal conductivity that utilizes change phase to transport heat. It was invented in Russia in the early 1980’s. The main parts of LHP are an evaporator, a condenser, a compensation chamber and a vapor and liquid lines. Only the evaporator and part of the compensation chamber are equipped with a wick structure. Inside loop heat pipe is working fluid. As a working fluid can be used distilled water, acetone, ammonia, methanol etc. Amount of filling is important for the operation and performance of LHP. This work deals with the design of loop heat pipe and impact of filling ratio of working fluid to remove waste heat from insulated gate bipolar transistor (IGBT.

  14. Amniotic fluid volume: Rapid MR-based assessment at 28-32 weeks gestation

    Energy Technology Data Exchange (ETDEWEB)

    Hilliard, N.J.; Hawkes, R.; Patterson, A.J.; Graves, M.J.; Priest, A.N.; Hunter, S.; Set, P.A.; Lomas, D.J. [Cambridge University Hospitals NHS Foundation Trust, Department of Radiology, Cambridge (United Kingdom); Lees, C. [Imperial College Healthcare NHS Trust, Department of Obstetrics and Fetal Medicine, London (United Kingdom)

    2016-10-15

    This work evaluates rapid magnetic resonance projection hydrography (PH) based amniotic fluid volume (AFV) estimates against established routine ultrasound single deepest vertical pocket (SDVP) and amniotic fluid index (AFI) measurements, in utero at 28-32 weeks gestation. Manual multi-section planimetry (MSP) based measurement of AFV is used as a proxy reference standard. Thirty-five women with a healthy singleton pregnancy (20-41 years) attending routine antenatal ultrasound were recruited. SDVP and AFI were measured using ultrasound, with same day MRI assessing AFV with PH and MSP. The relationships between the respective techniques were assessed using linear regression analysis and Bland-Altman method comparison statistics. When comparing estimated AFV, a highly significant relationship was observed between PH and the reference standard MSP (R{sup 2} = 0.802, p < 0.001). For the US measurements, SDVP measurement related most closely to amniotic fluid volume, (R{sup 2} = 0.470, p < 0.001), with AFI demonstrating a weaker relationship (R{sup 2} = 0.208, p = 0.007). This study shows that rapid MRI based PH measurement is a better predictor of AFV, relating more closely to our proxy standard than established US techniques. Although larger validation studies across a range of gestational ages are required this approach could form part of MR fetal assessment, particularly where poly- or oligohydramnios is suspected. (orig.)

  15. Amniotic fluid volume: Rapid MR-based assessment at 28-32 weeks gestation

    International Nuclear Information System (INIS)

    Hilliard, N.J.; Hawkes, R.; Patterson, A.J.; Graves, M.J.; Priest, A.N.; Hunter, S.; Set, P.A.; Lomas, D.J.; Lees, C.

    2016-01-01

    This work evaluates rapid magnetic resonance projection hydrography (PH) based amniotic fluid volume (AFV) estimates against established routine ultrasound single deepest vertical pocket (SDVP) and amniotic fluid index (AFI) measurements, in utero at 28-32 weeks gestation. Manual multi-section planimetry (MSP) based measurement of AFV is used as a proxy reference standard. Thirty-five women with a healthy singleton pregnancy (20-41 years) attending routine antenatal ultrasound were recruited. SDVP and AFI were measured using ultrasound, with same day MRI assessing AFV with PH and MSP. The relationships between the respective techniques were assessed using linear regression analysis and Bland-Altman method comparison statistics. When comparing estimated AFV, a highly significant relationship was observed between PH and the reference standard MSP (R"2 = 0.802, p < 0.001). For the US measurements, SDVP measurement related most closely to amniotic fluid volume, (R"2 = 0.470, p < 0.001), with AFI demonstrating a weaker relationship (R"2 = 0.208, p = 0.007). This study shows that rapid MRI based PH measurement is a better predictor of AFV, relating more closely to our proxy standard than established US techniques. Although larger validation studies across a range of gestational ages are required this approach could form part of MR fetal assessment, particularly where poly- or oligohydramnios is suspected. (orig.)

  16. Investigation into the Use of Water Based Brake Fluid for Light Loads

    Directory of Open Access Journals (Sweden)

    W. A. Akpan

    2012-12-01

    Full Text Available This paper addresses the possibility of using water based fluid as a brake fluid for light loads. Characterization of both standard and water based braked fluids formulated was carried out. The properties of the latter were compared with that of a standard commercial brake fluid. The actual test of the formulated brake fluid was carried out with a Nissan Sunny vehicle model 1.5 within the speed range of 20km/hr to 80km/hr at the permanent campus of University of Uyo and the braking efficiency obtained attest to its suitability for light loads.

  17. Thermodynamic performance of a double-effect absorption heat-transformer using TFE/E181 as the working fluid

    International Nuclear Information System (INIS)

    Zhao Zongchang; Zhang Xiaodong; Ma Xuehu

    2005-01-01

    Trifluoroethanol(TFE)-tetraethylenglycol dimethylether (TEGDME or E181) is a new organic working-pair which is non-corrosive, completely miscible and thermally stable up to 250 deg C. It is suitable for upgrading low-temperature level industrial waste-heat to a higher temperature level for reuse. In this paper, the thermodynamic performance of the double-effect absorption heat-transformer (DEAHT) using TFE/E181 as the working fluid is simulated, based on the thermodynamic properties of TFE/E181 solution. The results show that, when the temperature in the high-pressure generator exceeds 100 deg C and the gross temperature lift is 30 deg C, the coefficient of performance (COP) of the DEAHT is about 0.58, which is larger than the 0.48 of the single-stage absorption heat-transformer (SAHT), the increase of COP is about 20%. But it is still less than 0.64 of the DEAHT using LiBr-H 2 O as the working fluid. Meanwhile, the COP of the DEAHT decreases more rapidly with increases of the absorption temperature than that for the SAHT. The range of available gross temperature-lift for the DEAHT is narrower than that of the SAHT. The higher the temperature in the high-pressure generator, the larger the gross temperature-lift could be. So the double-effect absorption heat-transformer is more suitable for being applied in those circumstances of having a higher-temperature heat-resource and when a higher temperature-lift is not needed

  18. Emulsifiers performance on the stability of the drilling fluid base biodiesel; Desempenho de emulsificantes sobre a estabilidade de fluido de perfuracao a base de biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Giselle P.; Costa, Marta [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    This work was prepared six (6) formulations of biodiesel based drilling fluids. Three formulations in the proportion oil-water 70/30 and other three in 60/40, just varying the employed surfactants: new product derived the citric acid (developed at our laboratory) and two other commercial surfactants. After production the fluids, It was analyzed them performance of the products through rheological properties to 135 deg F , filtrate volume in HPHT to 500 psi and to 200 deg F, electric stability to 135 deg F and phase separation during seven days of rest. The rheological analyses allowed to determine the behavior every fluids, though flow curves. Those fluids presented same behavior of the fluids used in oil field (Binghamianos). The laboratory tests demonstrated that new surfactant reduced the filtrated volume and provided mechanics and thermic stability. (author)

  19. Thermodynamic analysis of an absorption refrigeration system with ionic-liquid/refrigerant mixture as a working fluid

    International Nuclear Information System (INIS)

    Kim, Yoon Jo; Kim, Sarah; Joshi, Yogendra K.; Fedorov, Andrei G.; Kohl, Paul A.

    2012-01-01

    Thermodynamics of an ionic-liquid (IL) based absorption refrigeration system has been numerically analyzed. It provides an alternative to the normally toxic working fluids, such as the ammonia in conventional absorption systems. The use of ILs also eliminates crystallization and metal-compatibility problems of the water/LiBr system. Mixtures of refrigerants and imidazolium-based ILs are theoretically explored as the working fluid pairs in a miniature absorption refrigeration system, so as to utilize waste-heat to power a refrigeration/heat pump system for electronics cooling. A non-random two-liquid (NRTL) model was built and used to predict the solubility of the mixtures. Saturation temperatures at the evaporator and condenser were set at 25 °C and 50 °C, respectively, with the power dissipation of 100 W. Water in combination with [emim][BF 4 ] (1-ethyl-3-methylimidazolium tetrafluoroborate) gave the highest coefficient of performance (COP) around 0.9. The refrigerant/IL compatibility indicated by the circulation ratio, alkyl chain length of the IL, and thermodynamic properties of the refrigerants, such as latent heat of evaporation were proven to be important factors in determining the performance of the absorption system. The negative effect of high viscosity was mitigated by dilution of the IL with the refrigerant and the use of slightly larger microfluidic channel heat exchangers. -- Highlights: ► Mixtures of refrigerant/ionic-liquid are studied for absorption system. ► We carry out comprehensive theoretical thermodynamic analysis. ► The essential factors of refrigerant/IL affecting the performance are identified. ► Water/[emim][BF 4 ] showed the best performance of COP. ► The effects of high viscosity ILs on the system performance are not significant.

  20. CO{sub 2}-based supercritical fluids as environmentally-friendly processing solvents

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Davenhall, L.B.; Taylor, C.M.V.; Pierce, T. [Los Alamos National Lab., NM (United States). Physical Organic Chemistry Group; Tiefert, K. [Hewlett-Packard Co., Inc., Santa Clara, CA (United States)

    1999-03-01

    The production of integrated circuits involves a number of discrete steps that utilize hazardous or regulated solvents. Environmental, safety and health considerations associated with these chemicals have prompted a search for alternative, more environmentally benign, solvent systems. An emerging technology for conventional solvent replacement is the use of supercritical fluids based on carbon dioxide (CO{sub 2}). Supercritical CO{sub 2} (SCCO{sub 2}) is an excellent choice for IC manufacturing processes since it is non-toxic, non-flammable, inexpensive, and is compatible with all substrate and metallizations systems. Also, conditions of temperature and pressure needed to achieve the supercritical state are easily achievable with existing process equipment. The authors first describe the general properties of supercritical fluids, with particular emphasis on their application as alternative solvents. Next, they review some of the work which has been published involving the use of supercritical fluids, and particularly CO{sub 2}, as they may be applied to the various steps of IC manufacture, including wafer cleaning, thin film deposition, etching, photoresist stripping, and waste treatment. Next, they describe the research work conducted at Los Alamos, on behalf of Hewlett-Packard, on the use of SCCO{sub 2} in a specific step of the IC manufacturing process: the stripping of hard-baked photoresist.

  1. Jobs to Manufacturing Careers: Work-Based Courses. Work-Based Learning in Action

    Science.gov (United States)

    Kobes, Deborah

    2016-01-01

    This case study, one of a series of publications exploring effective and inclusive models of work-based learning, finds that work-based courses bring college to the production line by using the job as a learning lab. Work-based courses are an innovative way to give incumbent workers access to community college credits and degrees. They are…

  2. Effects of heat loss as percentage of fuel's energy, friction and variable specific heats of working fluid on performance of air standard Otto cycle

    International Nuclear Information System (INIS)

    Lin, J.-C.; Hou, S.-S.

    2008-01-01

    The objective of this study is to analyze the effects of heat loss characterized by a percentage of the fuel's energy, friction and variable specific heats of working fluid on the performance of an air standard Otto cycle with a restriction of maximum cycle temperature. A more realistic and precise relationship between the fuel's chemical energy and the heat leakage that is based on a pair of inequalities is derived through the resulting temperature. The variations in power output and thermal efficiency with compression ratio, and the relations between the power output and the thermal efficiency of the cycle are presented. The results show that the power output as well as the efficiency where maximum power output occurs will increase with increase of the maximum cycle temperature. The temperature dependent specific heats of the working fluid have a significant influence on the performance. The power output and the working range of the cycle increase with the increase of specific heats of the working fluid, while the efficiency decreases with the increase of specific heats of the working fluid. The friction loss has a negative effect on the performance. Therefore, the power output and efficiency of the cycle decrease with increasing friction loss. It is noteworthy that the effects of heat loss characterized by a percentage of the fuel's energy, friction and variable specific heats of the working fluid on the performance of an Otto cycle engine are significant and should be considered in practical cycle analysis. The results obtained in the present study are of importance to provide good guidance for performance evaluation and improvement of practical Otto engines

  3. Optimization-based Fluid Simulation on Unstructured Meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Bridson, Robert; Erleben, Kenny

    2010-01-01

    for solving the fluid dynamics equations as well as direct access to the interface geometry data, making in- clusion of a new surface energy term feasible. Furthermore, using an unstructured mesh makes it straightforward to handle curved solid boundaries and gives us a possibility to explore several fluid...

  4. Seismoelectric Effects based on Spectral-Element Method for Subsurface Fluid Characterization

    Science.gov (United States)

    Morency, C.

    2017-12-01

    Present approaches for subsurface imaging rely predominantly on seismic techniques, which alone do not capture fluid properties and related mechanisms. On the other hand, electromagnetic (EM) measurements add constraints on the fluid phase through electrical conductivity and permeability, but EM signals alone do not offer information of the solid structural properties. In the recent years, there have been many efforts to combine both seismic and EM data for exploration geophysics. The most popular approach is based on joint inversion of seismic and EM data, as decoupled phenomena, missing out the coupled nature of seismic and EM phenomena such as seismoeletric effects. Seismoelectric effects are related to pore fluid movements with respect to the solid grains. By analyzing coupled poroelastic seismic and EM signals, one can capture a pore scale behavior and access both structural and fluid properties.Here, we model the seismoelectric response by solving the governing equations derived by Pride and Garambois (1994), which correspond to Biot's poroelastic wave equations and Maxwell's electromagnetic wave equations coupled electrokinetically. We will show that these coupled wave equations can be numerically implemented by taking advantage of viscoelastic-electromagnetic mathematical equivalences. These equations will be solved using a spectral-element method (SEM). The SEM, in contrast to finite-element methods (FEM) uses high degree Lagrange polynomials. Not only does this allow the technique to handle complex geometries similarly to FEM, but it also retains exponential convergence and accuracy due to the use of high degree polynomials. Finally, we will discuss how this is a first step toward full coupled seismic-EM inversion to improve subsurface fluid characterization. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  5. Physically-Based Rendering of Particle-Based Fluids with Light Transport Effects

    Science.gov (United States)

    Beddiaf, Ali; Babahenini, Mohamed Chaouki

    2018-03-01

    Recent interactive rendering approaches aim to efficiently produce images. However, time constraints deeply affect their output accuracy and realism (many light phenomena are poorly or not supported at all). To remedy this issue, in this paper, we propose a physically-based fluid rendering approach. First, while state-of-the-art methods focus on isosurface rendering with only two refractions, our proposal (1) considers the fluid as a heterogeneous participating medium with refractive boundaries, and (2) supports both multiple refractions and scattering. Second, the proposed solution is fully particle-based in the sense that no particles transformation into a grid is required. This interesting feature makes it able to handle many particle types (water, bubble, foam, and sand). On top of that, a medium with different fluids (color, phase function, etc.) can also be rendered.

  6. Effects of heat transfer, friction and variable specific heats of working fluid on performance of an irreversible dual cycle

    International Nuclear Information System (INIS)

    Chen Lingen; Ge Yanlin; Sun Fengrui; Wu Chih

    2006-01-01

    The thermodynamic performance of an air standard dual cycle with heat transfer loss, friction like term loss and variable specific heats of working fluid is analyzed. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle, are derived by detailed numerical examples. Moreover, the effects of variable specific heats of the working fluid and the friction like term loss on the irreversible cycle performance are analyzed. The results show that the effects of variable specific heats of working fluid and friction like term loss on the cycle performance are obvious, and they should be considered in practical cycle analysis. The results obtained in this paper may provide guidance for the design of practical internal combustion engines

  7. Performance of an Atkinson cycle with heat transfer, friction and variable specific-heats of the working fluid

    International Nuclear Information System (INIS)

    Ge Yanlin; Chen Lingen; Sun, Fengrui; Wu Chih

    2006-01-01

    The performance of an air standard Atkinson cycle with heat-transfer loss, friction-like term loss and variable specific-heats of the working fluid is analyzed using finite-time thermodynamics. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between the power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of variable specific-heats of the working fluid and the friction-like term loss on the irreversible cycle performance are analyzed. The results show that the effects of variable specific-heats of working fluid and friction-like term loss on the irreversible cycle performance should be considered in cycle analysis. The results obtained in this paper provide guidance for the design of Atkinson engines

  8. Mineral oil metal working fluids (MWFs)-development of practical criteria for mist sampling.

    Science.gov (United States)

    Simpson, A T; Groves, J A; Unwin, J; Piney, M

    2000-05-01

    Not all mineral oil metalworking fluids (MWFs) in common use form stable airborne mists which can be sampled quantitatively onto a filter. This much has been known for some time but no simple method of identifying oils too volatile for customary filter sampling has been developed. Past work was reviewed and experiments were done to select simple criteria which would enable such oils to be identified. The sampling efficiency for a range of commercial mineral oil MWF were assessed by drawing clean air through spiked filters at 2 l. min(-1) for periods up to 6 h before analysis. The physical properties of MWF are governed by their composition and kinematic viscosity was found to be the most practical and easily available index of the potential for sample loss from the filter. Oils with viscosities greater that 18 cSt (at 40 degrees C) lost less than 5% of their weight, whereas those with viscosities less than 18 cSt gave losses up to 71%. The losses from the MWF were mostly aliphatic hydrocarbons (C(10)-C(18)), but additives such as alkyl benzenes, esters, phenols and terpene odorants were also lost. The main recommendation to arise from the work is that filter sampling can be performed on mineral oils with viscosities of 18 cSt (at 40 degrees C) or more with little evaporative losses from the filter. However, sampling oils with viscosities less than 18 cSt will produce results which may significantly underestimate the true value. Over a quarter of UK mineral oil MWFs are formulated from mineral oils with viscosities less than 18 cSt (at 40 degrees C). The problem of exposure under-estimation and inappropriate exposure sampling could be widespread. Further work is being done on measurement of mixed phase mineral oil mist exposure.

  9. Improving the economy-of-scale of small organic rankine cycle systems through appropriate working fluid selection

    International Nuclear Information System (INIS)

    White, Martin; Sayma, Abdulnaser I.

    2016-01-01

    Highlights: • Novel system model coupling turbine and ORC system performance. • Contour plots to characterise working fluid and turbine performance. • Changing working fluid can expand pump and turbine operating envelope. • Possible to improve the economy-of-scale through optimal working fluid selection. - Abstract: Organic Rankine cycles (ORC) are becoming a major research area within the field of sustainable energy systems. However, a major challenge facing the widespread implementation of small and mini-scale ORC systems is the economy-of-scale. To overcome this challenge requires single components that can be manufactured in large volumes and then implemented into a wide variety of different applications where the heat source conditions may vary. The aim of this paper is to investigate whether working fluid selection can improve the current economy-of-scale by enabling the same system components to be used in multiple ORC systems. This is done through coupling analysis and optimisation of the energy process, with a performance map for a small-scale ORC radial turbine. The performance map, obtained using CFD, is adapted to account for additional loss mechanisms not accounted for in the original CFD simulation before being non-dimensionalised using a modified similitude theory developed for subsonic ORC turbines. The updated performance map is then implemented into a thermodynamic model, enabling the construction of a single performance contour that displays the range of heat source conditions that can be accommodated by the existing turbine whilst using a particular working fluid. Constructing this performance map for a range of working fluids, this paper demonstrates that through selecting a suitable working fluid, the same turbine can efficiently utilise heat sources between 360 and 400 K, with mass flow rates ranging between 0.5 and 2.75 kg/s respectively. This corresponds to using the same turbine in ORC applications where the heat available ranges

  10. Thermodynamic and economic optimizations of a waste heat to power plant driven by a subcritical ORC (Organic Rankine Cycle) using pure or zeotropic working fluid

    International Nuclear Information System (INIS)

    Le, Van Long; Kheiri, Abdelhamid; Feidt, Michel; Pelloux-Prayer, Sandrine

    2014-01-01

    This paper carried out the thermodynamic and economic optimizations of a subcritical ORC (Organic Rankine Cycle) using a pure or a zeotropic mixture working fluid. Two pure organic compounds, i.e. n-pentane and R245fa, and their mixtures with various concentrations were used as ORC working fluid for this study. Two optimizations, i.e. exergy efficiency maximization and LCOE (Levelized Cost of Electricity) minimization, were performed to find out the optimum operating conditions of the system and to determine the best working fluid from the studied media. Hot water at temperature of 150 °C and pressure of 5 bars was used to simulate the heat source medium. Whereas, cooling water at temperature of 20 °C was considered to be the heat sink medium. The mass flow rate of heat source is fixed at 50 kg/s for the optimizations. According to the results, the n-pentane-based ORC showed the highest maximized exergy efficiency (53.2%) and the lowest minimized LCOE (0.0863 $/kWh). Regarding ORCs using zeotropic working fluids, 0.05 and 0.1 R245fa mass fraction mixtures present the comparable economic features and thermodynamic performances to the system using n-pentane at minimum LCOE. The ORC using R245fa represents the least profitable system. - Highlights: • Thermoeconomic optimization is carried out for a subcritical ORC. • Exergy efficiency and Levelized Cost of Electricity are optimized. • R245fa, n-Pentane and their mixtures are used as ORC working fluid. • CO 2 emissions can be substantially reduced by waste heat recovery using an ORC

  11. Drivers of choice for fluid milk versus plant-based alternatives: What are consumer perceptions of fluid milk?

    Science.gov (United States)

    McCarthy, K S; Parker, M; Ameerally, A; Drake, S L; Drake, M A

    2017-08-01

    Fluid milk consumption has declined for decades while consumption of nondairy alternatives has increased. A better understanding of why consumers purchase fluid milk or nondairy alternatives is needed to assist increased sales of milk or maintain sales without further decline. The objective of this study was to determine the extrinsic attributes that drive purchase within each product category. The second objective was to determine the personal values behind the purchase of each beverage type to give further understanding why particular attributes are important. An online conjoint survey was launched with 702 dairy consumers, 172 nondairy consumers, and 125 consumers of both beverages. Individual means-end chain interviews were conducted with fluid milk consumers (n = 75), plant-based alternative consumers (n = 68), and consumers of both beverages (n = 78). Fat content was the most important attribute for dairy milk followed by package size and label claims. Consumers of fluid milk preferred 1 or 2% fat content, gallon, or half-gallon packaging, conventionally pasteurized store-brand milk. Sugar level was the most important attribute for plant-based beverages, followed by plant source and package size. Almond milk was the most desirable plant source, and half-gallon packaging was the most preferred packaging. Means-end chain interviews results suggested that maintaining a balanced diet and healthy lifestyle was important to all consumer groups. Lactose free was an important attribute for plant-based alternative consumers and consumers of both dairy and nondairy. A distinguishing characteristic of those who only drank nondairy plant-based alternatives was that plant-based beverages contributed to a goal to consume less animal products, beliefs about animal mistreatment, and perceived lesser effect on the environment than fluid milk. Unique to fluid milk consumers was that fluid milk was perceived as a staple food item. These results suggest that the dairy industry

  12. Crystallization from a milk-based revised simulated body fluid

    International Nuclear Information System (INIS)

    Dorozhkin, Sergey V; Dorozhkina, Elena I

    2007-01-01

    A milk-based revised simulated body fluid (milk-rSBF) was prepared by a conventional route but instead of deionized water, all necessary chemicals were dissolved in whole cow's milk (3.2% fat). In order to accelerate crystallization and increase the amount of precipitates, the influence of milk was studied from condensed solutions equal to four times the ionic concentrations of rSBF (4rSBF). The experiments were performed under physiological conditions (solution pH = 7.35-7.40, temperature 37.0 ± 0.2 deg. C, duration 7 days) in a constant-composition double-diffusion device, which provided a slow crystallization under strictly controlled conditions. Similar experiments with 4rSBF but dissolved in deionized water were used as a control. An extra set of experiments with 4rSBF dissolved in deionized water but with an addition of 40 g l -1 bovine serum albumin (BSA) was used as another control. The influence of milk appeared to be similar to that of dissolved BSA: some components of milk (presumably albumins and proteins) were found to co-precipitate with calcium phosphates, which had a strong negative influence on both the crystallinity and the crystal sizes of the precipitates. In addition, both milk and BSA strongly inhibited crystallization of calcium phosphates: the precipitates turned out to contain a minor amount of calcium phosphates and a substantial amount of organic phase

  13. Organic Rankine-cycle power systems working fluids study. Topical report No. 1: Fluorinol 85

    Science.gov (United States)

    Jain, M. L.; Demirgian, J. C.; Cole, R. L.

    1986-09-01

    The thermal stability limits and degradation rates of Fluorinol 85 as a function of maximum cycle temperatures are determined. Following the design and construction of a dynamic test loop capable of simulating the thermodynamic conditions of possible prototypical organic Rankine-cycle (ORC) power systems, several test runs were completed. The Fluorinol 85 test loop was operated for about 3800 h at a temperature range of 525 to 600 F. Both liquid and noncondensable vapor (gas) samples were drawn periodically and analyzed using capillary column gas chromatography, gas chromatography/mass spectrometry and mass spectrometry. Results indicate that Fluorinol 85 would not decompose significantly over an extended period, up to a maximum cycle temperature of 550 F. However, 506-h data at 575 F show initiation of significant degradation. The 770-h data at 600 F, using a fresh charge of Fluorinol 85, indicate an annual degradation rate of more than 17.2%. The most significant degradation product observed is hydrofluoric acid, which could cause severe corrosion in an ORC system. Removal of the hydrofluoric acid and prevention of temperature extremes are necessary for an ORC system using Fluorinol 85 as a working fluid.

  14. Brush seal leakage performance with gaseous working fluids at static and low rotor speed conditions

    Science.gov (United States)

    Carlile, Julie A.; Hendricks, Robert C.; Yoder, Dennis A.

    1992-01-01

    The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied. The leakage results included for air, helium, and carbon dioxide at several bristle/rotor interferences. Also, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in.), a fence height of 0.0635 cm (0.025 in.), and 1800 bristles/cm circumference (4500 bristles/in. circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.

  15. Generation of cross section data of heat pipe working fluids for compact nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Slewinski, Anderson; Ribeiro, Guilherme B. [Instituto Tecnológico de Aeronáutica (ITA), São José dos Campos, SP (Brazil); Caldeira, Alexandre D., E-mail: anderson_sle@live.com, E-mail: alexdc@ieav.cta.br, E-mail: gbribeiro@ieav.cta.br [Instituto de Estudos Avançados (IEAv), São José dos Campos, SP (Brazil). Divisão de Energia Nuclear

    2017-07-01

    For compact nuclear power plants, such as the nuclear space propulsion proposed by the TERRA project, aspects like mass, size and efficiency are essential drivers that must be managed during the project development. Moreover, for high temperature reactors, the use of liquid metal heat pipes as the heat removal mechanism provides some important advantages as simplicity and reliability. Considering these aforementioned aspects, this paper aims the development of the procedure necessary to calculate the microscopic absorption cross section data of several liquid metal to be used as working fluids with heat pipes; which will be later compared with the given data from JEF Report ⧣14. The information necessary to calculate the cross section data will be obtained from the latest ENDF library version. The NJOY system will be employed with the following modules: RECONR, BROADR, UNRESR and GROUPR, using the same specifications used to calculate the cross section data encountered in the JEF Report ⧣14. This methodology allows a comparison with published values, verifying the procedure developed to calculate the microscopic absorption cross section for selected isotopes using the TERRA reactor spectrum. Liquid metals isotopes of Sodium (Na), Lithium (Li), Thallium (TI) and Mercury (Hg) are part of this study. (author)

  16. Novel and conventional working fluid mixtures for solar Rankine cycles: Performance assessment and multi-criteria selection

    International Nuclear Information System (INIS)

    Mavrou, Paschalia; Papadopoulos, Athanasios I.; Stijepovic, Mirko Z.; Seferlis, Panos; Linke, Patrick; Voutetakis, Spyros

    2015-01-01

    This work investigates the performance of working fluid mixtures for use in solar ORC (Organic Rankine Cycle systems) with heat storage employing FPC (Flat Plate Collectors). Several mixtures are considered including conventional choices often utilized in ORC as well as novel mixtures previously designed using advanced computer aided molecular design methods (Papadopoulos et al., 2013). The impact of heat source variability on the ORC performance is assessed for different working fluid mixtures. Solar radiation is represented in detail through actual, hourly averaged data for an entire year. A multi-criteria mixture selection methodology unveils important trade-offs among several important system operating parameters and efficiently highlights optimum operating ranges. Such parameters include the ORC thermal efficiency, the net generated power, the volume ratio across the turbine, the mass flow rate of the ORC working fluid, the evaporator temperature glide, the temperature drop in the storage tank, the ORC total yearly operating duration, the required collector aperture area to generate 1 kW of power and the irreversibility. A mixture of neopentane – 2-fluoromethoxy-2-methylpropane at 70% neopentane is found to be the most efficient in all the considered criteria simultaneously. - Highlights: • Investigation of novel and conventional working fluid mixtures for solar ORCs. • Systematic, multi-criteria assessment methodology for mixture selection. • Simultaneous consideration of multiple important mixture performance criteria. • Effects of year-round solar variability in a solar ORC with heat storage tank

  17. Influence of thermophysical properties of working fluid on the design of cryogenic turboexpanders using nsds diagram

    International Nuclear Information System (INIS)

    Sam, Ashish A; Ghosh, Parthasarathi

    2015-01-01

    Cryogenic turboexpanders are an essential part of liquefaction and refrigeration plants. The thermodynamic efficiency of these plants depends upon the efficiency of the turboexpander, which is the main cold generating component of these plants, and therefore, they should be designed for high thermodynamic efficiencies. Balje's [1] n s d s chart, which is a contour of isentropic efficiencies plotted against specific speed and specific diameter, is commonly used for the preliminary design of cryogenic turboexpanders. But, these charts were developed based on calculations for a specific heat ratio (γ) of 1.4, and studies show that care should be taken while implementing the same for gases which have a higher γ of 1.67. Hence there is a need to investigate the extent of applicability of n s d s diagram in designing expansion turbines for higher specific heat ratios. In this paper, Computational Fluid Dynamics (CFD) analysis of cryogenic turboexpanders was carried out using Ansys CFX®. The turboexpanders were designed based on the methodologies prescribed by Kun and Sentz [2] following the n s d s diagram of Balje and Hasselgruber's technique for generating blade profile. The computational results of the two cases were analysed to investigate the applicability of Balje's n s d s diagram for the design of turboexpanders for refrigeration and liquefaction cycles. (paper)

  18. [Study of work accidents related to human body fluids exposure among health workers at a university hospital].

    Science.gov (United States)

    Balsamo, Ana Cristina; Felli, Vanda Elisa Andres

    2006-01-01

    This descriptive and exploratory study from a quantitative approach aimed to characterize workers who were victims of work accidents related to human body fluids exposure and to evaluate the accident victim care protocol. The population consisted of 48 workers who were victims of work accidents involving exposure to human body fluids, from July 2000 to June 2001. Data were collected through a form and interviews. Results showed that nursing workers presented higher accident risk levels and that 87.50% involved piercing and cutting material, such as needles and butterflies (70%). As to the accident-related situation/activity, the workers indicated that 25% were due to an "inadequate act during the procedure"; 19.64% mentioned that "it happened" and 29.17% answered that they did not have any suggestion. This study provided important tools to review and elaborate strategies to prevent accidents involving exposure to human body fluids.

  19. Waste-aware fluid volume assignment for flow-based microfluidic biochips

    DEFF Research Database (Denmark)

    Schneider, Alexander Rüdiger; Pop, Paul; Madsen, Jan

    2017-01-01

    complex Fluidic Units (FUs) such as switches, micropumps, mixers and separators can be constructed. When running a biochemical application on a FBMB, fluid volumes are dispensed from input reservoirs and used by the FUs. Given a biochemical application and a biochip, we are interested in determining...... the fluid volume assignment for each operation of the application, such that the FUs volume requirements are satisfied, while over- and underflow are avoided and the total volume of fluid used is minimized. We propose an algorithm for this fluid assignment problem. Compared to previous work, our method...

  20. Effect of condensation temperature glide on the performance of organic Rankine cycles with zeotropic mixture working fluids

    International Nuclear Information System (INIS)

    Liu, Qiang; Duan, Yuanyuan; Yang, Zhen

    2014-01-01

    Highlights: • A condensation pressure determination method for ORC with zeotropic mixture is given. • The effects of condensation temperature glide on the ORC performance are analyzed. • Mixture mole fractions for the maximum power output of a geothermal ORC are identified. • The biomass ORC performance with part of the latent heat transferred in the IHE is analyzed. - Abstract: The organic Rankine cycle (ORC) has been widely used to convert low-grade ( 2 M) selected as working fluids for the cogenerative ORC driven by the biomass energy. Two optimal working fluid mole fractions maximize the cycle efficiency, exergy efficiency and net power output for cooling water temperature increases less than the maximum condensation temperature glide, while the highest net power output appears at the higher mole fraction of the more volatile component for the geothermal ORC when the condensation temperature glide of the working fluid mixture matches the cooling water temperature increase. Higher condensation temperature glides result in large thermal loss to the heat sink and exergy destruction in the condenser. There is only one optimal working fluid mole fraction that maximizes the thermal efficiency, exergy efficiency and net power output when the cooling water temperature increase is greater than the condensation temperature glide

  1. Analysis of temperature glide matching of heat pumps with zeotropic working fluid mixtures for different temperature glides

    DEFF Research Database (Denmark)

    Zühlsdorf, Benjamin; Jensen, Jonas Kjær; Cignitti, Stefano

    2018-01-01

    refrigerants. This approach enables a match of the temperature glide of sink and source with the temperature of the working fluid during phase change and thus, a reduction of the exergy destruction due to heat transfer. The model was evaluated for four different boundary conditions. The exergy destruction due...

  2. Performance Analysis and Working Fluid Selection of a Supercritical Organic Rankine Cycle for Low Grade Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Yourong Li

    2012-08-01

    Full Text Available The performance analysis of a supercritical organic Rankine cycle system driven by exhaust heat using 18 organic working fluids is presented. Several parameters, such as the net power output, exergy efficiency, expander size parameter (SP, and heat exchanger requirement of evaporator and the condenser, were used to evaluate the performance of this recovery cycle and screen the working fluids. The results reveal that in most cases, raising the expander inlet temperature is helpful to improve the net power output and the exergy efficiency. However, the effect of the expander inlet pressure on those parameters is related to the expander inlet temperature and working fluid used. Either lower expander inlet temperature and pressure, or higher expander inlet temperature and pressure, generally makes the net power output more. Lower expander inlet temperature results in larger total heat transfer requirement and expander size. According to the screening criteria of both the higher output and the lower investment, the following working fluids for the supercritical ORC system are recommended: R152a and R143a.

  3. Collaborative Communication in Work Based Learning Programs

    Science.gov (United States)

    Wagner, Stephen Allen

    2017-01-01

    This basic qualitative study, using interviews and document analysis, examined reflections from a Work Based Learning (WBL) program to understand how utilizing digital collaborative communication tools influence the educational experience. The Community of Inquiry (CoI) framework was used as a theoretical frame promoting the examination of the…

  4. Mathematical modeling of the dynamic stability of fluid conveying pipe based on integral equation formulations

    International Nuclear Information System (INIS)

    Elfelsoufi, Z.; Azrar, L.

    2016-01-01

    In this paper, a mathematical modeling of flutter and divergence analyses of fluid conveying pipes based on integral equation formulations is presented. Dynamic stability problems related to fluid pressure, velocity, tension, topography slope and viscoelastic supports and foundations are formulated. A methodological approach is presented and the required matrices, associated to the influencing fluid and pipe parameters, are explicitly given. Internal discretizations are used allowing to investigate the deformation, the bending moment, slope and shear force at internal points. Velocity–frequency, pressure-frequency and tension-frequency curves are analyzed for various fluid parameters and internal elastic supports. Critical values of divergence and flutter behaviors with respect to various fluid parameters are investigated. This model is general and allows the study of dynamic stability of tubes crossed by stationary and instationary fluid on various types of supports. Accurate predictions can be obtained and are of particular interest for a better performance and for an optimal safety of piping system installations. - Highlights: • Modeling the flutter and divergence of fluid conveying pipes based on RBF. • Dynamic analysis of a fluid conveying pipe with generalized boundary conditions. • Considered parameters fluid are the pressure, tension, slopes topography, velocity. • Internal support increase the critical velocity value. • This methodologies determine the fluid parameters effects.

  5. Benchmark Simulation of Natural Circulation Cooling System with Salt Working Fluid Using SAM

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, K. K.; Scarlat, R. O.; Hu, R.

    2017-09-03

    Liquid salt-cooled reactors, such as the Fluoride Salt-Cooled High-Temperature Reactor (FHR), offer passive decay heat removal through natural circulation using Direct Reactor Auxiliary Cooling System (DRACS) loops. The behavior of such systems should be well-understood through performance analysis. The advanced system thermal-hydraulics tool System Analysis Module (SAM) from Argonne National Laboratory has been selected for this purpose. The work presented here is part of a larger study in which SAM modeling capabilities are being enhanced for the system analyses of FHR or Molten Salt Reactors (MSR). Liquid salt thermophysical properties have been implemented in SAM, as well as properties of Dowtherm A, which is used as a simulant fluid for scaled experiments, for future code validation studies. Additional physics modules to represent phenomena specific to salt-cooled reactors, such as freezing of coolant, are being implemented in SAM. This study presents a useful first benchmark for the applicability of SAM to liquid salt-cooled reactors: it provides steady-state and transient comparisons for a salt reactor system. A RELAP5-3D model of the Mark-1 Pebble-Bed FHR (Mk1 PB-FHR), and in particular its DRACS loop for emergency heat removal, provides steady state and transient results for flow rates and temperatures in the system that are used here for code-to-code comparison with SAM. The transient studied is a loss of forced circulation with SCRAM event. To the knowledge of the authors, this is the first application of SAM to FHR or any other molten salt reactors. While building these models in SAM, any gaps in the code’s capability to simulate such systems are identified and addressed immediately, or listed as future improvements to the code.

  6. Mathematical foundation of the optimization-based fluid animation method

    DEFF Research Database (Denmark)

    Erleben, Kenny; Misztal, Marek Krzysztof; Bærentzen, Jakob Andreas

    2011-01-01

    We present the mathematical foundation of a fluid animation method for unstructured meshes. Key contributions not previously treated are the extension to include diffusion forces and higher order terms of non-linear force approximations. In our discretization we apply a fractional step method to ...

  7. A refractometry-based glucose analysis of body fluids.

    Science.gov (United States)

    Zirk, Kai; Poetzschke, Harald

    2007-05-01

    In principle, refractometry appears to be a suitable method for the measurement of glucose concentrations in body fluids (such as blood and the intercellular fluid), even though the refractive index of the measured samples, as an additive property, is not specific. But, if certain conditions are fulfilled, the glucose content can be calculated using the refractive index in combination with values from a further measurement. This study describes the determination of the glucose content using refractometry in human blood serum derivates, which were selected - due to their ready availability - to be used as a model for interstitial fluid. Refractometry of body fluids requires the elimination of disturbing components from the measurement sample. First of all, a homogenous fluid (i.e. consisting of one phase) is required, so that all cells and components in suspension need to be separated out. Furthermore, certain dissolved macromolecular components which are known to disturb the measurement process must also be removed. In human serum samples which had been ultrafiltrated with a range of ultrafilters of different pore sizes, a comparative evaluation showed that only ultrafiltration through a filter with a separation limit of between 3 and 30kDa resulted in maximal reduction of the refractive index (compared to native serum), whereas ultrafilters with greater separation limits did not. The total content of osmotically active solutes (the tonicity) also exerts a clear influence. However, exemplary measurements in blood plasma fluid from one volunteer showed that the electrical conductivity is (without an additive component) directly proportional to the osmolality: physiological changes in the state of body hydration (hyperhydration and dehydration) do not lead to any considerable changes in the relation between ionised and uncharged solute particles, but instead result in a sufficiently clear dilution or concentration of the blood fluid's low molecular components. This

  8. Effect of working fluids on the performance of a novel direct vapor generation solar organic Rankine cycle system

    International Nuclear Information System (INIS)

    Li, Jing; Alvi, Jahan Zeb; Pei, Gang; Ji, Jie; Li, Pengcheng; Fu, Huide

    2016-01-01

    Highlights: • A novel, flexible direct vapor generation solar ORC is proposed. • Technical feasibility of the system is discussed. • Fluid effect on collector efficiency is explored. • The system is more efficient than solar ORC with HTF. - Abstract: A novel solar organic Rankine cycle (ORC) system with direct vapor generation (DVG) is proposed. A heat storage unit is embedded in the ORC to guarantee the stability of power generation. Compared with conventional solar ORCs, the proposed system avoids the secondary heat transfer intermediate and shows good reaction to the fluctuation of solar radiation. The technical feasibility of the system is discussed. Performance is analyzed by using 17 dry and isentropic working fluids. Fluid effects on the efficiencies of ORC, collectors and the whole system are studied. The results indicate that the collector efficiency generally decreases while the ORC and system efficiencies increase with the increment in fluid critical temperature. At evaporation temperature of 120 °C and solar radiation of 800 Wm −2 , the ORC, collector and overall thermal efficiencies of R236fa are 10.59, 56.14 and 5.08% while their values for Benzene are 12.5, 52.58 and 6.57% respectively. The difference between collector efficiencies using R236fa and Benzene gets larger at lower solar radiation. The heat collection is strongly correlated with latent and sensible heat of the working fluid. Among the fluids, R123 exhibits the highest overall performance and seems to be suitable for the proposed system in the short term.

  9. RED WINE EXTRACT OBTAINED BY MEMBRANE-BASED SUPERCRITICAL FLUID EXTRACTION: PRELIMINARY CHARACTERIZATION OF CHEMICAL PROPERTIES.

    Directory of Open Access Journals (Sweden)

    W. Silva

    Full Text Available ABSTRACT This study aims to obtain an extract from red wine by using membrane-based supercritical fluid extraction. This technique involves the use of porous membranes as contactors during the dense gas extraction process from liquid matrices. In this work, a Cabernet Sauvignon wine extract was obtained from supercritical fluid extraction using pressurized carbon dioxide as solvent and a hollow fiber contactor as extraction setup. The process was continuously conducted at pressures between 12 and 18 MPa and temperatures ranged from 30 to 50ºC. Meanwhile, flow rates of feed wine and supercritical CO2 varied from 0.1 to 0.5 mL min-1 and from 60 to 80 mL min-1 (NCPT, respectively. From extraction assays, the highest extraction percentage value obtained from the total amount of phenolic compounds was 14% in only one extraction step at 18MPa and 35ºC. A summarized chemical characterization of the obtained extract is reported in this work; one of the main compounds in this extract could be a low molecular weight organic acid with aromatic structure and methyl and carboxyl groups. Finally, this preliminary characterization of this extract shows a remarkable ORAC value equal to 101737 ± 5324 µmol Trolox equivalents (TE per 100 g of extract.

  10. The rheological responds of the superparamagnetic fluid based on Fe{sub 3}O{sub 4} hollow nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, Xiaohui; Pei, Lei; Xuan, Shouhu, E-mail: xuansh@ustc.edu.cn; Yan, Qifan; Gong, Xinglong, E-mail: gongxl@ustc.edu.cn

    2017-05-01

    In this work, a superparamagnetic fluid based on Fe{sub 3}O{sub 4} hollow nanospheres was developed and the influence of the particle structure on the rheological properties was investigated. The Fe{sub 3}O{sub 4} hollow nanospheres which were prepared by using the hydrothermal method presented the superparamagnetic characteristic, and the magnetic fluid thereof showed well magnetorheological (MR) effect. The stable magnetic fluid had a high yield stress even at low shear rate and its maximal yield stress was dramatically influenced by the measurement gap. In comparison to the Fe{sub 3}O{sub 4} nanoparticles based magnetic fluid (MF), the Fe{sub 3}O{sub 4} hollow nanospheres based MF exhibited better MR effect and higher stability since the unique hollow nanostructure. The shear stress of the hollow nanospheres is about 1.85 times larger than the nanoparticles based MF because it formed stronger chains structure under applying a magnetic field. To further investigate the enhancing mechanism, a molecule dynamic simulation was conducted to analyze the shear stress and the structure evolution of the Fe{sub 3}O{sub 4} hollow nanospheres based MF and the simulation matched well with the experimental results. - Highlights: • A superparamagnetic fluid based on Fe{sub 3}O{sub 4} hollow nanospheres was investigated. • The stable magnetic fluid had a high yield stress even at low shear rate. • The shear stress of the hollow nanospheres is large. • A molecule dynamic simulation was conducted to analyze the shear stress.

  11. Complex fluid network optimization and control integrative design based on nonlinear dynamic model

    International Nuclear Information System (INIS)

    Sui, Jinxue; Yang, Li; Hu, Yunan

    2016-01-01

    In view of distribution according to complex fluid network’s needs, this paper proposed one optimization computation method of the nonlinear programming mathematical model based on genetic algorithm. The simulation result shows that the overall energy consumption of the optimized fluid network has a decrease obviously. The control model of the fluid network is established based on nonlinear dynamics. We design the control law based on feedback linearization, take the optimal value by genetic algorithm as the simulation data, can also solve the branch resistance under the optimal value. These resistances can provide technical support and reference for fluid network design and construction, so can realize complex fluid network optimization and control integration design.

  12. Implementation of an evidence-based guideline on fluid resuscitation: lessons learnt for future guidelines

    NARCIS (Netherlands)

    Tabbers, M.M.; Boluyt, N.; Offringa, M.

    2010-01-01

    There is little experience with the nationwide implementation of an evidence-based pediatric guideline on first-choice fluid for resuscitation in hypovolemia. We investigated fluid prescribing behavior at (1) guideline development, (2) after guideline development, and (3) after active implementation

  13. A Generalised Assessment of Working Fluids and Radial Turbines for Non-Recuperated Subcritical Organic Rankine Cycles

    Directory of Open Access Journals (Sweden)

    Martin T. White

    2018-03-01

    Full Text Available The aim of this paper is to conduct a generalised assessment of both optimal working fluids and radial turbine designs for small-scale organic Rankine cycle (ORC systems across a range of heat-source temperatures. The former has been achieved by coupling a thermodynamic model of subcritical, non-recperated cycles with the Peng–Robinson equation of state, and optimising the working-fluid and cycle parameters for heat-source temperatures ranging between 80 ° C and 360 ° C . The critical temperature of the working fluid is found to be an important parameter governing working-fluid selection. Moreover, a linear correlation between heat-source temperature and the optimal critical temperature that achieves maximum power output has been found for heat-source temperatures below 300 ° C ( T cr = 0.830 T hi + 41.27 . This correlation has been validated against cycle calculations completed for nine predefined working fluids using both the Peng–Robinson equation of state and using the REFPROP program. Ultimately, this simple correlation can be used to identify working-fluid candidates for a specific heat-source temperature. In the second half of this paper, the effect of the heat-source temperature on the optimal design of a radial-inflow turbine rotor for a 25 kW subcritical ORC system has been studied. As the heat-source temperature increases, the optimal blade-loading coefficient increases, whilst the optimal flow coefficient reduces. Furthermore, passage losses are dominant in turbines intended for low-temperature applications. However, at higher heat-source temperatures, clearance losses become more dominant owing to the reduced blade heights. This information can be used to identify the most direct route to efficiency improvements in these machines. Finally, it is observed that the transition from a conventional converging stator to a converging-diverging stator occurs at heat-source temperatures of approximately 165 ° C , whilst radially

  14. Analysis and optimization of three main organic Rankine cycle configurations using a set of working fluids with different thermodynamic behaviors

    Science.gov (United States)

    Hamdi, Basma; Mabrouk, Mohamed Tahar; Kairouani, Lakdar; Kheiri, Abdelhamid

    2017-06-01

    Different configurations of organic Rankine cycle (ORC) systems are potential thermodynamic concepts for power generation from low grade heat. The aim of this work is to investigate and optimize the performances of the three main ORC systems configurations: basic ORC, ORC with internal heat exchange (IHE) and regenerative ORC. The evaluation for those configurations was performed using seven working fluids with typical different thermodynamic behaviours (R245fa, R601a, R600a, R227ea, R134a, R1234ze and R1234yf). The optimization has been performed using a genetic algorithm under a comprehensive set of operative parameters such as the fluid evaporating temperature, the fraction of flow rate or the pressure at the steam extracting point in the turbine. Results show that there is no general best ORC configuration for all those fluids. However, there is a suitable configuration for each fluid. Contribution to the topical issue "Materials for Energy harvesting, conversion and storage II (ICOME 2016)", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  15. Selection of appropriate working fluids for Rankine cycles used for recovery of heat from exhaust gases of ICE in heavy-duty series hybrid electric vehicles

    International Nuclear Information System (INIS)

    Jung, Daebong; Park, Sungjin; Min, Kyoungdoug

    2015-01-01

    Recently, the waste heat recovery system is studied for application in vehicles to improve fuel economy. Especially, Rankine cycle is representative and attractive technology as waste heat recovery system. In order to maximize efficiency of Rankine cycle in the vehicle application, selection of optimal working fluid is important. Thus, in this study, thermodynamic analysis with consideration of practical operating condition was conducted to find out optimal working fluids. Thermodynamic efficiency, recovery efficiency, and overall cycle efficiency were adopted to estimate Rankine cycle performance. In order to reflect practical operating condition on the analysis, limitations due to working fluid physical properties and components specifications are taken into account. 5 working fluids including dry and wet fluid were used to estimate efficiency. Consequently, R245fa which shows high efficiency and environment-friendly is suggested as optimal working fluid in vehicle application. - Highlights: • 5 different working fluids were analyzed in respect of hybrid electric vehicle waste heat recovery system. • Real world operational conditions and limits are applied. • Optimal heating temperature of each working fluid show different trend. • R245fa is preferable among other fluids due to its high efficiency and impact on environment

  16. DNA hydrogel-based supercapacitors operating in physiological fluids

    Science.gov (United States)

    Hur, Jaehyun; Im, Kyuhyun; Hwang, Sekyu; Choi, ByoungLyong; Kim, Sungjee; Hwang, Sungwoo; Park, Nokyoung; Kim, Kinam

    2013-01-01

    DNA nanostructures have been attractive due to their structural properties resulting in many important breakthroughs especially in controlled assemblies and many biological applications. Here, we report a unique energy storage device which is a supercapacitor that uses nanostructured DNA hydrogel (Dgel) as a template and layer-by-layer (LBL)-deposited polyelectrolyte multilayers (PEMs) as conductors. Our device, named as PEM-Dgel supercapacitor, showed excellent performance in direct contact with physiological fluids such as artificial urine and phosphate buffered saline without any need of additional electrolytes, and exhibited almost no cytotoxicity during cycling tests in cell culture medium. Moreover, we demonstrated that the PEM-Dgel supercapacitor has greater charge-discharge cycling stability in physiological fluids than highly concentrated acid electrolyte solution which is normally used for supercapacitor operation. These conceptually new supercapacitors have the potential to be a platform technology for the creation of implantable energy storage devices for packageless applications directly utilizing biofluids. PMID:23412432

  17. Hypersensitivity pneumonitis due to metal working fluids: Sporadic or under reported?

    Science.gov (United States)

    Gupta, Amit; Rosenman, Kenneth D

    2006-06-01

    Occupational exposure to metal working fluids (MWF) is common with over 1.2 million workers in the United States involved in machine finishing, machine tooling, and other metalworking operations. MWF is a known cause of hypersensitivity pneumonitis (HP). Recent reports of outbreaks of hypersensitivity HP secondary to exposure to MWF are reported. Cases were identified through the Occupational Disease surveillance system in the State of Michigan and from referrals for evaluation to the Division of Occupational and Environmental Medicine at Michigan State University (MSU). Each patient underwent a clinical examination including an occupational history, lung function studies, radiographic imaging, and in some cases lung biopsies. Following the diagnosis of definite HP, an industrial hygiene investigation was carried out, which included a plant walk-through, and review of the "Injury and Illness" log. Air monitoring and microbial sampling results were reviewed. As part of Michigan's mandatory surveillance system for occupational illnesses, seven cases of suspected HP were identified in 2003-2004 from three facilities manufacturing automobile parts in Michigan. Each plant used semi-synthetic MWFs, and conducted a MWF management program including biocide additions. Two facilities had recently changed the MWF before the cases arose. Growth of mycobacteria was found in these two MWFs. Breathing zone samples for particulates of two employees in plant A (two cases) ranged from 0.48 to 0.56 mg/m3. In plant B (four cases), two employees' sampling results ranged from 0.10 to 0.14 mg/m3. No air sampling data were available from plant C. Hypersensitivity pneumonitis due to exposure to MWFs is under-recognized by health care providers, and current surveillance systems are inadequate to provide a true estimate of its occurrence. HP arose from environments with exposures well below the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for MWF, and

  18. Fluid emulsion base potential of shea butter | Oyedele | Journal of ...

    African Journals Online (AJOL)

    SB emulsion formulations were prepared from the fluid SB/LP blends by homogenizing each at 1:9 ratio (v/v) with potassium hydroxide (KOH) aqueous solution (0.1, 0.2, 0.4, or 0.6 M concentration, respectively), and with 0.2 M KOH at different mixing ratios (2:8, 3:7, 4:6, or 5:5 v/v), respectively. The physical consistency and ...

  19. Development of drilling fluids based on polysaccharides and natural minerals

    Directory of Open Access Journals (Sweden)

    Zhanar Nurakhmetova

    2016-03-01

    Full Text Available The technology of oil well drilling in complex geological conditions by applying the drilling muds based on the polysaccharides – gellan, xanthan and their mixture which potentially possess a good flocculation properties and the ability to reversible sol-gel transition in dependence of temperature and concentration of low molecular weight cations in water has been justified in this work. For the preparation of drilling muds, gellan and xanthan were used, these polymers were obtained from biomass by an aerobic fermentation using microorganisms Sphingomonas elodea and Xanthomonas campestris. Bentonite was used as a natural mineral. Physical and chemical characteristics of aqueous and aqueous-salt solutions of natural polysaccharide gellan including: density, intrinsic and effective viscosity, static shear stress, dynamic shear stress, sedimentation stability and other parameters were determined while varying polymer compositions and concentrations, ionic strength of the solution, nature of low molecular weight salts, concentration of dispersion phase, pH of the medium and temperature.

  20. Computational Fluid Dynamics Based Extraction of Heat Transfer Coefficient in Cryogenic Propellant Tanks

    Science.gov (United States)

    Yang, H. Q.; West, Jeff

    2015-01-01

    Current reduced-order thermal model for cryogenic propellant tanks is based on correlations built for flat plates collected in the 1950's. The use of these correlations suffers from: inaccurate geometry representation; inaccurate gravity orientation; ambiguous length scale; and lack of detailed validation. The work presented under this task uses the first-principles based Computational Fluid Dynamics (CFD) technique to compute heat transfer from tank wall to the cryogenic fluids, and extracts and correlates the equivalent heat transfer coefficient to support reduced-order thermal model. The CFD tool was first validated against available experimental data and commonly used correlations for natural convection along a vertically heated wall. Good agreements between the present prediction and experimental data have been found for flows in laminar as well turbulent regimes. The convective heat transfer between tank wall and cryogenic propellant, and that between tank wall and ullage gas were then simulated. The results showed that commonly used heat transfer correlations for either vertical or horizontal plate over predict heat transfer rate for the cryogenic tank, in some cases by as much as one order of magnitude. A characteristic length scale has been defined that can correlate all heat transfer coefficients for different fill levels into a single curve. This curve can be used for the reduced-order heat transfer model analysis.

  1. Bartter syndrome prenatal diagnosis based on amniotic fluid biochemical analysis.

    Science.gov (United States)

    Garnier, Arnaud; Dreux, Sophie; Vargas-Poussou, Rosa; Oury, Jean-François; Benachi, Alexandra; Deschênes, Georges; Muller, Françoise

    2010-03-01

    Bartter syndrome is an autosomic recessive disease characterized by severe polyuria and sodium renal loss. The responsible genes encode proteins involved in electrolyte tubular reabsorption. Prenatal manifestations, mainly recurrent polyhydramnios because of fetal polyuria, lead to premature delivery. After birth, polyuria leads to life-threatening dehydration. Prenatal genetic diagnosis needs an index case. The aim of this study was to analyze amniotic fluid biochemistry for the prediction of Bartter syndrome. We retrospectively studied 16 amniotic fluids of Bartter syndrome-affected fetuses diagnosed after birth, only six of them being genetically proven. We assayed total proteins, alpha-fetoprotein, and electrolytes and defined a Bartter index corresponding to the multiplication of total protein and of alpha-fetoprotein. Results were compared with two control groups matched for gestational age-non-Bartter polyhydramnios (n = 30) and nonpolyhydramnios (n = 60). In Bartter syndrome, we observed significant differences (p Bartter index (0.16, 0.82, and 1.0, respectively). No statistical difference was observed for electrolytes. In conclusion, Bartter syndrome can be prenatally suspected on amniotic fluid biochemistry (sensitivity 93% and specificity 100%), allowing appropriate management before and after birth.

  2. Numerical analysis of splashing fluid using hybrid method of mesh-based and particle-based modelings

    International Nuclear Information System (INIS)

    Tanaka, Nobuatsu; Ogawara, Takuya; Kaneda, Takeshi; Maseguchi, Ryo

    2009-01-01

    In order to simulate splashing and scattering fluid behaviors, we developed a hybrid method of mesh-based model for large-scale continuum fluid and particle-based model for small-scale discrete fluid particles. As for the solver of the continuum fluid, we adopt the CIVA RefIned Multiphase SimulatiON (CRIMSON) code to evaluate two phase flow behaviors based on the recent computational fluid dynamics (CFD) techniques. The phase field model has been introduced to the CRIMSON in order to solve the problem of loosing phase interface sharpness in long-term calculation. As for the solver of the discrete fluid droplets, we applied the idea of Smoothed Particle Hydrodynamics (SPH) method. Both continuum fluid and discrete fluid interact each other through drag interaction force. We verified our method by applying it to a popular benchmark problem of collapse of water column problems, especially focusing on the splashing and scattering fluid behaviors after the column collided against the wall. We confirmed that the gross splashing and scattering behaviors were well reproduced by the introduction of particle model while the detailed behaviors of the particles were slightly different from the experimental results. (author)

  3. Computer analysis of an adiabatic Stirling cryocooler using a two-phase two-component working fluid

    International Nuclear Information System (INIS)

    Renfroe, D.A.; Cheung, C.M.

    1992-01-01

    This paper describes the performance and behavior of a Stirling cyrocooler incorporating a working fluid composed of helium and nitrogen. At the operating temperature of the cryocooler (80 K), the nitrogen component will condense in the freezer section. It is shown that the phase change in the working fluid increased the heat lifted for a given size and weight of machine and the coefficient of performance. The magnitude of these effects was dependent on the mass ratio of nitrogen to helium, phase angle between the compression and expansion processes, and the ratio of the compression space volume to the expansion space volume. The optimum heat lifted performance was obtained for a mass ratio of four parts of nitrogen to one part of helium, a phase angle of approximately 100 degrees, and a volume ratio of two which resulted in a heat lifted increase of 75% over the single phase, 90 degree phase angle configuration. The coefficient of performance showed a 20% improvement

  4. Performance of Partially-Hydrolyzed Polyacrylamide in Water Based Drilling Fluids

    Directory of Open Access Journals (Sweden)

    Ali Reza Nasiri*

    2013-05-01

    Full Text Available Fluid properties with constant improvement in efficiency have been noticeable as important criteria in drilling operation. The main drilling fluid properties highly depend on utilization of new polymers with high efficiency in drilling fluid composition. In this paper, the performance of a new polymer, called partially hydrolyzed polyacrylamide polymer (PHPA, is studied which has recently entered the drilling fluids industry in Iran. Hence viscosity property, fluid loss control and shale inhibition of this polymer have been evaluated based on an international standard method of API-13-I by considering the drilling and operational priorities of thecountry. Then the thermal effect, salt contaminants such as sodium chloride, calcium chloride, magnesium chloride and pH tolerance effect as major pollution indicators are also investigated in relation to polymeric fluid properties. The results obtained by the tests show that furthermore polymer PHPA increases rheological properties (apparent viscosity, plastic fluidity and yield point and it plays important role in increases in fluid loss. This polymer has also demonstrated acceptable resistance toward sodium chloride contaminants, but its efficiency decreases toward calcium and magnesium ion contaminants. The thermal tests show that polymer PHPA has high thermal stability up to 150°C. This polymer improves shale inhibition property and by encapsulation mechanism prevents dispersion of shale cuttings into the drilling fluid system as it stops any changes in fluid properties which will finally results inwellbore stability.

  5. Theoretical research on working fluid selection for a high-temperature regenerative transcritical dual-loop engine organic Rankine cycle

    International Nuclear Information System (INIS)

    Tian, Hua; Liu, Lina; Shu, Gequn; Wei, Haiqiao; Liang, Xingyu

    2014-01-01

    Highlights: • Among all examined working fluids, toluene possesses the maximum W net , highest η e and η ec . • The increase of T 3 worsens system performance, decreasing W net , η e and η ec . • Condenser C LT and turbine T LT possesses the least system irreversibility. • Turbines and exhaust evaporators are optimization components. - Abstract: In this paper, a regenerative transcritical dual-loop organic Rankine cycle is proposed to recover the waste heat of the exhaust, engine coolant and all the residual heat of the HT loop. Double regenerators are adopted in this system. Transcritical cycles are used in both loops. Hexamethyldisiloxane (MM), octamethyl cyclotetrasiloxane (D 4 ), octamethyltrisiloxane (MDM), cyclohexane, toluene and n-decane are chosen as the candidate working fluids of the HT loop and R143a is chosen as the working fluid of the LT loop. Influences of inlet temperature of turbine T HT (T 3 ) on mass flow rates (m f,HT and m f,LT ), net output power (W net ), energy conversion efficiency (η ec ), volumetric expansion ratio (VER), ratio of power consumed to power output (COR) and component irreversibility are analyzed and performance comparison of these working fluids is also evaluated. Results show that toluene possesses the maximum W net (42.46 kW), highest η e (51.92%) and η ec (12.77%). The increase of T 3 worsens system performance, decreasing W net , η e and η ec . Condenser C LT and turbine T LT possess the least system irreversibility. In addition, turbines and exhaust evaporators are optimized components

  6. Estimation and Uncertainty Analysis of Flammability Properties for Computer-aided molecular design of working fluids for thermodynamic cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    Computer Aided Molecular Design (CAMD) is an important tool to generate, test and evaluate promising chemical products. CAMD can be used in thermodynamic cycle for the design of pure component or mixture working fluids in order to improve the heat transfer capacity of the system. The safety......, there is no information about the reliability of the data. Furthermore, the global optimality of the GC parameters estimation is often not ensured....

  7. Thermo-Economic Analysis of Zeotropic Mixtures and Pure Working Fluids in Organic Rankine Cycles for Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Florian Heberle

    2016-03-01

    Full Text Available We present a thermo-economic analysis of an Organic Rankine Cycle (ORC for waste heat recovery. A case study for a heat source temperature of 150 °C and a subcritical, saturated cycle is performed. As working fluids R245fa, isobutane, isopentane, and the mixture of isobutane and isopentane are considered. The minimal temperature difference in the evaporator and the condenser, as well as the mixture composition are chosen as variables in order to identify the most suitable working fluid in combination with optimal process parameters under thermo-economic criteria. In general, the results show that cost-effective systems have a high minimal temperature difference ΔTPP,C at the pinch-point of the condenser and a low minimal temperature difference ΔTPP,E at the pinch-point of the evaporator. Choosing isobutane as the working fluid leads to the lowest costs per unit exergy with 52.0 €/GJ (ΔTPP,E = 1.2 K; ΔTPP,C = 14 K. Considering the major components of the ORC, specific costs range between 1150 €/kW and 2250 €/kW. For the zeotropic mixture, a mole fraction of 90% isobutane leads to the lowest specific costs per unit exergy. A further analysis of the ORC system using isobutane shows high sensitivity of the costs per unit exergy for the selected cost estimation methods and for the isentropic efficiency of the turbine.

  8. Is an alcoholic fixative fluid used for manual liquid-based cytology accurate to perform HPV tests?

    Directory of Open Access Journals (Sweden)

    Garbar C

    2011-12-01

    Full Text Available Christian Garbar1, Corinne Mascaux1, Philippe De Graeve2, Philippe Delvenne31Department of Biopathology, Institute Jean Godinot, Reims Cedex, France; 2Centre de Pathologie des Coteaux, Toulouse, France; 3Department of Pathology, University of Liege, Tour de Pathologie, Domaine Universitaire du Sart Tilman, Liège, BelgiumAbstract: In Europe, the alternative centrifuge method of liquid-based cytology is widely used in cervical screening. Turbitec® (Labonord SAS, Templemars, France is a centrifuge method of liquid-based cytology using an alcoholic fixative fluid, Easyfix® (Labonord. It is now well accepted that the association of liquid-based cytology and human papillomavirus test is indissociable of cervical screening. The aim of this work was to demonstrate that Easyfix alcoholic fluid is reliable to perform Hybrid Capture® 2 (QIAGEN SAS, Courtaboeuf, France. In this study, 75 patients with colposcopy for cervical lesions served as gold standard. A sample was collected, at random, for Easyfix fixative cytological fluid and for Digene Cervical Sampler (QIAGEN. The results of Hybrid Capture 2 (with relative light unit >1 showed no statistical difference, a positive Spearman’s correlation (r = 0.82, P < 0.0001, and a kappa value of 0.87 (excellent agreement between the two fluids. It was concluded that Easyfix is accurate to use in human papillomavirus tests with Hybrid Capture 2.Keywords: human papillomavirus, hybrid capture 2, Turbitec®, cervix cytology, liquid-based cytology

  9. Risk-based Comparative Study of Fluid Power Pitch Concepts

    DEFF Research Database (Denmark)

    Liniger, Jesper; Pedersen, Henrik Clemmensen; N. Soltani, Mohsen

    2017-01-01

    Proper functioning of the pitch system is essential to both normal operation and safety critical shut down of modern multi megawatt wind turbines. Several studies on field failure rates for such turbines show that pitch systems are a major contributor to failures which entails an increased risk....... Thus, more reliable and safe concepts are needed. A review of patents and patent applications covering fluid power pitch concepts, reveals that many propose closed-type hydraulic systems. This paper proposes a closed-type concept with a bootstrap reservoir. In contrary to a conventional system where...

  10. Respiratory Adaptations in Acid-base Disturbances: Role of Cerebral Fluids,

    Science.gov (United States)

    1979-06-19

    The respiratory and metabolic components of acid-base homeostasis are defined. A quantitative empirical description of the (incomplete) mutual...literature. Respiratory adaptations in steady acid-base disturbances of metabolic origin (hyperventilation with hypocapnia in primary metabolic acidosis, and...hypoventilation with hypercapnia in metabolic alkalosis ) are analyzed as a function of the acidity of the cerebral fluids (cerebrospinal and cerebral interstitial fluid). (Author)

  11. On the relationship between executive functions of working memory and components derived from fluid intelligence measures.

    Science.gov (United States)

    Ren, Xuezhu; Schweizer, Karl; Wang, Tengfei; Chu, Pei; Gong, Qin

    2017-10-01

    The aim of the current study is to provide new insights into the relationship between executive functions and intelligence measures in considering the item-position effect observed in intelligence items. Raven's Advanced Progressive Matrices (APM) and Horn's LPS reasoning test were used to assess fluid intelligence which served as criterion in investigating the relationship between intelligence and executive functions. A battery of six experimental tasks measured the updating, shifting, and inhibition processes of executive functions. Data were collected from 205 university students. Fluid intelligence showed substantial correlations with the updating and inhibition processes and no correlation with the shifting process without considering the item-position effect. Next, the fixed-link model was applied to APM and LPS data separately to decompose them into an ability component and an item-position component. The results of relating the components to executive functions showed that the updating and shifting processes mainly contributed to the item-position component whereas the inhibition process was mainly associated with the ability component of each fluid intelligence test. These findings suggest that improvements in the efficiency of updating and shifting processes are likely to occur during the course of completing intelligence measures and inhibition is important for intelligence in general. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Predicting fluid responsiveness with transthoracic echocardiography is not yet evidence based

    DEFF Research Database (Denmark)

    Wetterslev, M; Haase, N; Johansen, R R

    2013-01-01

    an integrated tool in the intensive care unit, this systematic review examined studies evaluating the predictive value of TTE for fluid responsiveness. In October 2012, we searched Pubmed, EMBASE and Web of Science for studies evaluating the predictive value of TTE-derived variables for fluid responsiveness...... responsiveness. Of the 4294 evaluated citations, only one study fully met our inclusion criteria. In this study, the predictive value of variations in inferior vena cava diameter (> 16%) for fluid responsiveness was moderate with sensitivity of 71% [95% confidence interval (CI) 44-90], specificity of 100% (95......% CI 73-100) and an area under the receiver operating curve of 0.90 (95% CI 0.73-0.98). Only one study of TTE-based methods fulfilled the criteria for valid assessment of fluid responsiveness. Before recommending the use of TTE in predicting fluid responsiveness, proper evaluation including...

  13. Optimization of organo clay production for applications in based oil drilling fluid; Otimizacao do processo de organofilizacao para aplicacoes em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Heber S; Martins, Alice B; Costa, Danubia L. da; Ferreira, Heber C; Neves, Gelmires de A; Melo, Tomas J.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Teixeira Neto, Erico [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2008-07-01

    The organophilic clays are widely used as an agent dispersed in the composition of oil based drilling fluids. The organophilic clays are gotten from bentonite clays treated, in watery way, with ionic surfactants, that are adsorbed in the surface of interlayer of the clays, re-covered them with a organic layer. A fundamental stage of production of the organophilic clays is the dispersion of bentonite clays, in way that variables like: speed of agitation, temperature and time of cure, influences directly in plastic and apparent viscosities of these dispersions, together with other variables of organophilization process, like, temperature and time of cure of organophilization, has direct influence in efficiency of the organophilization process. This work considers a study of these variable, using bentonite clays: Brasgel PA{sup R} and Cloisite Na{sup +R}, treated with the ionic surfactant Praepagem WB{sup R}. The organophilic clays gotten had been characterized by rays X diffraction, Foster's swelling, and the results were compared with the commercial organophilic clay VG-69{sup R}, industrially treated with ionic surfactant. Viscosities plastic and apparent of the dispersions had been measured in the midst of organic dispersant diesel oil used to obtain the oil based drilling fluids. Preliminary results of Foster's swelling and preparation of fluids show that the clays have affinity with the means liquid organic dispersants, and the fluids meet specifications of PETROBRAS (N-22581-1997 and N-2259 to 1997) for use in the of diesel oil based drilling fluids. (author)

  14. Oil base fluids without tensoactive additives; Fluidos a base de oleo sem tensoativos

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Jose Carlos V; Aragao, Atila Fernando L [PETROBRAS, XX (Brazil). Centro de Desenvolvimento de Recursos Humanos Norte e Nordeste

    1990-12-31

    The goal of this paper is to define an ideal oil base fluid composition without tensoactive additives, since these may cause damage to producing formation during drilling or well completion. We investigated the rheological, filtrating and phase separation properties of the systems composed of diesel oil, organophilic clay and a polar agent (water or ethyl alcohol). In order to to that, we used the 286 Baroid digital rotating viscometer, filtrating cells standardized according to the American Petroleum Institute (AP) for temperatures of 25 deg C to 149 deg C and pressures of 6,89 x 10{sup 5} Pa (100 psig) to 3,44 x 10{sup 6} (500 psig), and the setting method, according to the determinations of respectively rheological, filtrating and phase separation parameters. Results proved that the composition: diesel oil-94% v/v, Na Cl saturated solution - 6% v/v and bentone - 17,1 to 22,8 kg/m{sup 3} (6 to 8 lb/bbl), is ideal to meet the properties required for drilling and well completion operations for low densities, that is 0,84% to 1,02 (6,9 to 8,5 ib/gal). In order to obtain densities in the interval of 1,02 to 1,14 (8,5 to 9,5 ib/gal) the system should be condensed with calcite (Ca CO{sub 3}) and the base fluid composition should be : diesel oil-94 to 98% v/v, Na Cl saturated solution - 2 to 6% v/v and bentone 17,1 to 22,8 kg/m{sup 3} (6 to 8 ib/bbl). The average cost per barrel for the systems studied here is of the same order of conventional oil base fluids (with tensoactive additives). (author) 13 refs., 7 figs., 3 tabs.

  15. Oil base fluids without tensoactive additives; Fluidos a base de oleo sem tensoativos

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Jose Carlos V.; Aragao, Atila Fernando L. [PETROBRAS, XX (Brazil). Centro de Desenvolvimento de Recursos Humanos Norte e Nordeste

    1989-12-31

    The goal of this paper is to define an ideal oil base fluid composition without tensoactive additives, since these may cause damage to producing formation during drilling or well completion. We investigated the rheological, filtrating and phase separation properties of the systems composed of diesel oil, organophilic clay and a polar agent (water or ethyl alcohol). In order to to that, we used the 286 Baroid digital rotating viscometer, filtrating cells standardized according to the American Petroleum Institute (AP) for temperatures of 25 deg C to 149 deg C and pressures of 6,89 x 10{sup 5} Pa (100 psig) to 3,44 x 10{sup 6} (500 psig), and the setting method, according to the determinations of respectively rheological, filtrating and phase separation parameters. Results proved that the composition: diesel oil-94% v/v, Na Cl saturated solution - 6% v/v and bentone - 17,1 to 22,8 kg/m{sup 3} (6 to 8 lb/bbl), is ideal to meet the properties required for drilling and well completion operations for low densities, that is 0,84% to 1,02 (6,9 to 8,5 ib/gal). In order to obtain densities in the interval of 1,02 to 1,14 (8,5 to 9,5 ib/gal) the system should be condensed with calcite (Ca CO{sub 3}) and the base fluid composition should be : diesel oil-94 to 98% v/v, Na Cl saturated solution - 2 to 6% v/v and bentone 17,1 to 22,8 kg/m{sup 3} (6 to 8 ib/bbl). The average cost per barrel for the systems studied here is of the same order of conventional oil base fluids (with tensoactive additives). (author) 13 refs., 7 figs., 3 tabs.

  16. Performance of the mineral blended ester oil-based drilling fluid systems

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, A.R.; Kamis, A.; Foo, K.S. [University Teknologi (Malaysia)

    2001-06-01

    A study was conducted in which the properties of ester oil-based drilling fluid systems were examined using a blended mixture of ester and synthetic mineral oil. Biodegradable invert emulsion ester-based fluids are preferred over mineral oil-based drilling fluids for environmental reasons, but they tend to cause alkaline hydrolysis resulting in solidification of the drilling fluid systems. The drilling fluid examined here consisted of Malaysian palm oil ester derivatives (methyl laureate ester or isopropyl laureate ester) blended with commercially available synthetic mineral oil. This mineral oil was added to reduce the problem of alkaline hydrolysis. This mixture, however, was found to be unstable and could not solve the problem at high temperature. The isopropyl laureate and mineral oil blended system was more stable towards the hydrolysis process up to 250 degrees F. In order to enhance the performance of an invert emulsion drilling fluid system, it was recommended that brine water content of the fluid system be lowered. 3 refs., 2 figs.

  17. A magneto-rheological fluid-based torque sensor for smart torque wrench application

    Science.gov (United States)

    Ahmadkhanlou, Farzad; Washington, Gregory N.

    2013-04-01

    In this paper, the authors have developed a new application where MR fluid is being used as a sensor. An MR-fluid based torque wrench has been developed with a rotary MR fluid-based damper. The desired set torque ranges from 1 to 6 N.m. Having continuously controllable yield strength, the MR fluid-based torque wrench presents a great advantage over the regular available torque wrenches in the market. This design is capable of providing continuous set toque from the lower limit to the upper limit while regular torque wrenches provide discrete set torques only at some limited points. This feature will be especially important in high fidelity systems where tightening torque is very critical and the tolerances are low.

  18. Microdroplet-based universal logic gates by electrorheological fluid

    KAUST Repository

    Zhang, Mengying

    2011-01-01

    We demonstrate a uniquely designed microfluid logic gate with universal functionality, which is capable of conducting all 16 logic operations in one chip, with different input voltage combinations. A kind of smart colloid, giant electrorheological (GER) fluid, functions as the translation media among fluidic, electronic and mechanic information, providing us with the capability of performing large integrations either on-chip or off-chip, while the on-chip hybrid circuit is formed by the interconnection of the electric components and fluidic channels, where the individual microdroplets travelling in a channel represents a bit. The universal logic gate reveals the possibilities of achieving a large-scale microfluidic processor with more complexity for on-chip processing for biological, chemical as well as computational experiments. © 2011 The Royal Society of Chemistry.

  19. A single photon emission computed tomograph based on a limited dumber of detectors for fluid flow visualization

    International Nuclear Information System (INIS)

    Legoupil, S.

    1999-01-01

    We present in this work a method for fluid flow visualization in a system using radioactive tracers. The method is based on single photon emission computed tomography techniques, applied to a limited number of discrete detectors. We propose in this work a method for the estimation of the transport matrix of photons, associated to the acquisition system. This method is based on the modelization of profiles acquired for a set of point sources located in the imaged volume. Monte Carlo simulations allow to separate scattered photons from those directly collected by the system. The influence of the energy tracer is exposed. The reconstruction method is based on the maximum likelihood - expectation maximization algorithm. An experimental device, based on 36 detectors was realised for the visualization of water circulation in a vessel. A video monitoring allows to visualize the dye water tracer. Dye and radioactive tracers are injected simultaneously in a water flow circulating in the vessel. Reconstructed and video images are compared. Quantitative and qualitative analysis show that fluid flow visualization is feasible with a limited number of detectors. This method can be applied for system involving circulations of fluids. (author)

  20. Sensory ERPs predict differences in working memory span and fluid intelligence.

    Science.gov (United States)

    Brumback, Carrie R; Low, Kathy A; Gratton, Gabriele; Fabiani, Monica

    2004-02-09

    The way our brain reacts to sensory stimulation may provide important clues about higher-level cognitive function and its operation. Here we show that short-latency (memory span, as well as between subjects scoring high and low on a fluid intelligence test. Our findings also suggest that this link between sensory responses and complex cognitive tasks is modality specific (visual sensory measures correlate with visuo-spatial tasks whereas auditory sensory measures correlate with verbal tasks). We interpret these findings as indicating that people's effectiveness in controlling attention and gating sensory information is a critical determinant of individual differences in complex cognitive abilities.

  1. Contourlet domain multiband deblurring based on color correlation for fluid lens cameras.

    Science.gov (United States)

    Tzeng, Jack; Liu, Chun-Chen; Nguyen, Truong Q

    2010-10-01

    Due to the novel fluid optics, unique image processing challenges are presented by the fluidic lens camera system. Developed for surgical applications, unique properties, such as no moving parts while zooming and better miniaturization than traditional glass optics, are advantages of the fluid lens. Despite these abilities, sharp color planes and blurred color planes are created by the nonuniform reaction of the liquid lens to different color wavelengths. Severe axial color aberrations are caused by this reaction. In order to deblur color images without estimating a point spread function, a contourlet filter bank system is proposed. Information from sharp color planes is used by this multiband deblurring method to improve blurred color planes. Compared to traditional Lucy-Richardson and Wiener deconvolution algorithms, significantly improved sharpness and reduced ghosting artifacts are produced by a previous wavelet-based method. Directional filtering is used by the proposed contourlet-based system to adjust to the contours of the image. An image is produced by the proposed method which has a similar level of sharpness to the previous wavelet-based method and has fewer ghosting artifacts. Conditions for when this algorithm will reduce the mean squared error are analyzed. While improving the blue color plane by using information from the green color plane is the primary focus of this paper, these methods could be adjusted to improve the red color plane. Many multiband systems such as global mapping, infrared imaging, and computer assisted surgery are natural extensions of this work. This information sharing algorithm is beneficial to any image set with high edge correlation. Improved results in the areas of deblurring, noise reduction, and resolution enhancement can be produced by the proposed algorithm.

  2. Fluid, electrolyte, and acid-base balances in three-day, combined-training horses.

    Science.gov (United States)

    White, S L

    1998-04-01

    Horses competing in 3-day, combined-training events develop a metabolic acidosis that is partially compensated for by a respiratory alkalosis immediately after phases B and D. By the end of phase C and 30 minutes to 2 hours after phase D, the acidosis is resolved by the oxidation of lactate, and a metabolic alkalosis prevails. A reduction in TBW and cation content occurs, which often is not replenished 12 to 24 hours after the event, even though the serum or plasma concentration of various constituents may be within normal limits. Hypochloremia and hypocalcemia, however, may persist 12 or more hours after the speed and endurance test. All of the data cited in this article are from horses that successfully completed their respective tests. Nevertheless, some horses developed substantial fluid and cation losses. In horses that are not well conditioned or in competitions in which terrain, footing, or hot environments increase the thermal load or decrease heat loss, greater losses of fluids and electrolytes can be expected. Body weight losses exceeding 5% and cation losses exceeding 4000 mEq/L occur in endurance horses suffering from exhaustion and synchronous diaphragmatic flutter. In one study, two thirds of the Na+ lost during exercise-induced sweating in cool, dry conditions was replenished from salt supplements added to a balanced forage and concentrated diet. Consequently, horses in regular training and competition may benefit from salt supplementation. The composition of the salt supplement and the amount fed should be based on the composition of the horse's diet, degree of work, and environmental conditions. Horses competing in a 3-day, combined-training event may be expected to have persistent losses of weight and cations, particularly if conditions result in heavy sweating. Many horses in the field studies had minimal changes in weight and cation balance compared with pre-event values. The diet and electrolyte supplementation of the horses in the majority of

  3. Optimum performance analysis of an irreversible Diesel heat engine affected by variable heat capacities of working fluid

    International Nuclear Information System (INIS)

    Zhao, Yingru; Chen, Jincan

    2007-01-01

    An irreversible cycle model of the Diesel heat engine is established in which the temperature dependent heat capacities of the working fluid, the irreversibilities resulting from non-isentropic compression and expansion processes and heat leak losses through the cylinder wall are taken into account. The adiabatic equation of ideal gases with temperature dependent heat capacity is strictly deduced without using the additional approximation condition in the relevant literature and is used to analyze the performance of the Diesel heat engine. Expressions for the work output and efficiency of the cycle are derived by introducing the pressure ratio and the compression and expansion efficiencies. The performance characteristic curves of the Diesel heat engine are presented for a set of given parameters. The optimum criteria of some important parameters such as the work output, efficiency, pressure ratio and temperatures of the working fluid are obtained. Moreover, the influence of the compression and expansion efficiencies, variable heat capacities, heat leak and other parameters on the performance of the cycle is discussed in detail. The results obtained may provide a theoretical basis for both optimal design and operation of real Diesel heat engines

  4. Metal-Organic Frameworks in Adsorption-Driven Heat Pumps: The Potential of Alcohols as Working Fluids.

    Science.gov (United States)

    de Lange, Martijn F; van Velzen, Benjamin L; Ottevanger, Coen P; Verouden, Karlijn J F M; Lin, Li-Chiang; Vlugt, Thijs J H; Gascon, Jorge; Kapteijn, Freek

    2015-11-24

    A large fraction of global energy is consumed for heating and cooling. Adsorption-driven heat pumps and chillers could be employed to reduce this consumption. MOFs are often considered to be ideal adsorbents for heat pumps and chillers. While most published works to date on this topic have focused on the use of water as a working fluid, the instability of many MOFs to water and the fact that water cannot be used at subzero temperatures pose certain drawbacks. The potential of using alcohol-MOF pairs in adsorption-driven heat pumps and chillers is investigated. To this end, 18 different selected MOF structures in combination with either methanol or ethanol as a working fluid are considered, and their potential is assessed on the basis of adsorption measurements and thermodynamic efficiencies. If alcohols are used instead of water, then (1) adsorption occurs at lower relative pressures for methanol and even lower pressure for ethanol, (2) larger pores can be utilized efficiently, as hysteresis is absent for pores smaller than 3.4 nm (2 nm for water), (3) larger pore sizes need to be employed to ensure the desired stepwise adsorption, (4) the effect of (polar/apolar) functional groups in the MOF is far less pronounced, (5) the energy released or taken up per cycle is lower, but heat and mass transfer may be enhanced, (6) stability of MOFs seems to be less of an issue, and (7) cryogenic applications (e.g., ice making) become feasible. From a thermodynamic perspective, UiO-67, CAU-3, and ZIF-8 seem to be the most promising MOFs for both methanol and ethanol as working fluids. Although UiO-67 might not be completely stable, both CAU-3 and ZIF-8 have the potential to be applied, especially in subzero-temperature adsorption chillers (AC).

  5. Characterization of working fluid in vertically mounted finned U-shape twin heat pipe for electronic cooling

    International Nuclear Information System (INIS)

    Elnaggar, Mohamed H.A.; Abdullah, M.Z.; Abdul Mujeebu, M.

    2012-01-01

    Highlights: ► Detailed characterization of working fluid of vertical finned U-shape heat pipe. ► The present configuration, considering the working fluid, was not studied previously. ► The low difference in evaporator and condenser temperatures enhances heat transfer. ► The high pressure drop across the porous wick causes easy return flow of the liquid. ► The predicted evaporator and condenser temperatures are validated by experiment. - Abstract: As part of the ongoing research on finned U-shape heat pipes for CPU cooling, the present work focuses on the characterization of working fluid in vertically oriented twin U-shape heat pipe, by taking into account the gravity of flow. Two-dimensional FE simulation is performed under natural and forced convection modes, by using ANSYS-FLOTRAN. The best heat input and coolant velocity for the simulations are determined experimentally, corresponding to the least thermal resistance. The wall temperatures at the evaporator, adiabatic and condenser sections, and the velocity and pressure distributions of vapor and liquid, are analyzed. The total heat input for minimum thermal resistance in both natural and forced convection is found to be 50 W, and the coolant velocity is 3 m/s. The predicted and experimental wall temperatures are found in excellent match. It is observed that for the present U-shape heat pipe configuration, the difference in evaporator and condenser temperatures is significantly small, resulting in enhanced heat transfer compared to the conventional heat pipes. The sintered copper wick has a small pore size, resulting in low wick permeability, leading to the generation of high capillary forces for anti-gravity applications.

  6. Numerical Analysis of an Organic Rankine Cycle with Adjustable Working Fluid Composition, a Volumetric Expander and a Recuperator

    Directory of Open Access Journals (Sweden)

    Peter Collings

    2017-03-01

    Full Text Available Conventional Organic Rankine Cycles (ORCs using ambient air as their coolant cannot fully utilize the greater temperature differential available to them during the colder months. However, changing the working fluid composition so its boiling temperature matches the ambient temperature as it changes has been shown to have potential to increase year-round electricity generation. Previous research has assumed that the cycle pressure ratio is able to vary without a major loss in the isentropic efficiency of the turbine. This paper investigates if small scale ORC systems that normally use positive-displacement expanders with fixed expansion ratios could also benefit from this new concept. A numerical model was firstly established, based on which a comprehensive analysis was then conducted. The results showed that it can be applied to systems with positive-displacement expanders and improve their year-round electricity generation. However, such an improvement is less than that of the systems using turbine expanders with variable expansion ratios. Furthermore, such an improvement relies on heat recovery via the recuperator. This is because expanders with a fixed expansion ratio have a relatively constant pressure ratio between their inlet and outlet. The increase of pressure ratio between the evaporator and condenser by tuning the condensing temperature to match colder ambient condition in winter cannot be utilised by such expanders. However, with the recuperator in place, the higher discharging temperature of the expander could increase the heat recovery and consequently reduce the heat input at the evaporator, increasing the thermal efficiency and the specific power. The higher the amount of heat energy transferred in the recuperator, the higher the efficiency improvement.

  7. Evaluation of glycerol derivative as emulsifier for oil based drilling fluids; Avaliacao de derivados de glicerina como emulsificante para fluidos de perfuracao de base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Susan A. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Escola de Quimica; Cavalcanti, Milena Y.; Rodrigues Junior, Jorge; Lachter, Elizabeth R.; Nascimento, Regina Sandra V. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Inst. de Quimica

    2008-07-01

    In view of the growing search for new applications for the surplus glycerine of biodiesel production, the use of a glycerine derivative as emulsifier in oil based muds is proposed in this work. Glycerine monooleate was synthesized through esterification reaction, and characterized by NMR{sup 13}C. Its applicability as emulsifier was verified through electric stability tests performed on inverted phase drilling fluids. The obtained results were compared with two formulations containing different emulsifiers (sorbitol monooleate and trimethylolpropane monooleate). It was also evaluated the rheological properties of the formulated fluids through standard tests. It was verified that the fluid that contained the glycerine derivative showed considerably better electric stability results than the other systems. It also presented rheological properties similar to the ones shown by the system that contained the commercial emulsifier (sorbitol monooleate). Thus, it was found that glycerine monooleate is a potential substitute to the currently emulsifiers (author)

  8. Magnetic resonance study of maghemite-based magnetic fluid

    International Nuclear Information System (INIS)

    Figueiredo, L.C.; Lacava, B.M.; Skeff Neto, K.; Pelegrini, F.; Morais, P.C.

    2008-01-01

    This study reports on the magnetic resonance (MR) data (X-band experiment) of 10.2 nm average diameter maghemite nanoparticle in the temperature range of 100-230 K. Maghemite nanoparticles were suspended as low-pH ionic magnetic fluid containing 2.3x10 17 particles/cm 3 . The temperature dependence of both resonance linewidth and resonance field of the zero-field-cooled sample as well as the resonance field of the field-cooled sample (angular variation experiment) was analyzed using well-established methodology. Information regarding particle size, particle clusterization and surface magnetic anisotropy were obtained from the analysis of the MR data. The number of magnetic sites per particle from the MR data is in excellent agreement with the number provided by the transmission electron microscopy (TEM) data. The demagnetizing field value obtained from the MR data indicates cluster of particles containing on average 1.42 particles. The MR angular variation data suggest that magnetoelastic effect accounts for the non-linearity observed for the surface component of the magnetic anisotropy

  9. Investigation into the use of water based brake fluid for light loads ...

    African Journals Online (AJOL)

    The actual test of the formulated brake fluid was carried out with a Nissan Sunny vehicle model 1.5 within the speed range of 20km/hr to 80km/hr at the permanent campus· of University of Uyo and the· braking effiqiency obtained at test to its suitability for light loads. Keywords·: Water-based, Brake fluid properties, Light loads ...

  10. Comparison of theories of anisotropy in transformer oil-based magnetic fluids

    OpenAIRE

    Kúdelčík, Jozef; Bury, Peter; Drga, Jozef; Kopčanský, Peter; Závišová, Vlasta; Timko, Milan

    2013-01-01

    The external magnetic field in transformer oil-based magnetic fluids leads to the aggregation of magnetic nanoparticles and formation of clusters. These aggregations are the result of the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs. However, the temperature of magnetic fluids has also very important influence on the structural changes because the mechanism of thermal motion acts against the cluster creation. The acoustic spectroscopy ...

  11. Improvement in the Performance of Potato Starch Used in the Water-Based Drilling Fluid via Its Chemical Modification by Grafting Copolymerization

    Directory of Open Access Journals (Sweden)

    M. Abdollahi

    2013-01-01

    Full Text Available Increasing the thermal stability and resistance to bacterial attack (bioresistance of the potato starch used in the water-based drilling fluid is the aim of this work. Four types of potato starch grafted with acrylamide and a mixture of each one with acrylic acid, 2-acrylamido-2-methyl-1-propane sulfuric acid and itaconic acid were synthesized by manganese (IV-induced redox system at the suitable concentrations of initiator and monomer(s. FTIR spectroscopy was used to verify the grafting of monomers onto the starch. The effect of grafted starches on the rheological and fluid loss properties before and after aging of the water-based drilling fluid prepared with fresh water, 4% saline and the South applied method were investigated. The results showed that temperature and aging of fluid enhance the rheological and fluid loss control properties of water-based drilling fluids prepared in the presence of grafted starches. In other words, grafted starches are stable against thermal degradation and can be used in the formulation of water-based drilling fluids for drilling of deep wells.

  12. Fluid mechanics

    International Nuclear Information System (INIS)

    Paraschivoiu, I.; Prud'homme, M.; Robillard, L.; Vasseur, P.

    2003-01-01

    This book constitutes at the same time theoretical and practical base relating to the phenomena associated with fluid mechanics. The concept of continuum is at the base of the approach developed in this work. The general advance proceeds of simple balances of forces as into hydrostatic to more complex situations or inertias, the internal stresses and the constraints of Reynolds are taken into account. This advance is not only theoretical but contains many applications in the form of solved problems, each chapter ending in a series of suggested problems. The major part of the applications relates to the incompressible flows

  13. Study of smectite clays of the city Pedra Lavrada - PB for use in water-based drilling fluids

    International Nuclear Information System (INIS)

    Silva, I.A. da; Costa, J.M.R.; Cardoso, M.A.F.; Neves, G.A.; Ferreira, H.C.

    2011-01-01

    Paraiba has large reserves of bentonite clays, with the largest deposits in Boa Vista, PB. Recently new deposits were discovered in the cities of Cubati and Pedra Lavrada-PB, creating great expectations for further expansion of reserves for industrial production. The aim of this work is the study of smectite clays from the city of Pedra Lavrada, PB for use in drilling fluids water based. The characterization was made by the diffraction of laser (AG), thermogravimetric and differential thermal analysis (TGA and DTA), chemical composition by X-ray fluorescence (EDX), X-ray diffraction (XRD), exchange capacity of cations (ECC) and surface area (SA). The results obtained so far showed that the samples presented at its mineral composition smectite, kaolinite and quartz. In relation to rheological properties showed that the bentonite clay sample Dark presents promising features for use in water based drilling fluids. (author)

  14. Organophilization of bentonite clays with non-ionic surfactants aiming their use in drilling fluids base oil

    International Nuclear Information System (INIS)

    Silva, I.A.; Costa, J.M.R.; Neves, G.A.; Ferreira, H.C.; Ferreira, H.S.

    2010-01-01

    The use of nonionic surfactants has been replacing the traditional ionic surfactants among others by its high potential for resistance to thermal degradation. This work aims at the development of organoclay by the addition of nonionic surfactants for use in drilling fluids for oil wells based oil. The bentonite clay was organophilized and then characterized by X-ray diffraction and swelling Foster, seeking the most appropriate choice of surfactant to liquid organic dispersing media: ester, diesel and paraffin. With the obtained dispersions were measured apparent viscosities and plastic. The results showed that incorporation of surfactants used in the clay interlayer spacing increased significantly and that the dispersions showed rheological properties within the specifications of PETROBRAS, for the use of organophilic clays in drilling fluids in a non-aqueous base. (author)

  15. Evaluation of absorbents for an absorption heat pump using natural organic working fluids (eco-energy city project)

    Energy Technology Data Exchange (ETDEWEB)

    Hisajima, Daisuke; Sakiyama, Ryoko; Nishiguchi, Akira [Hitachi Ltd., Tsuchiura (Japan). Mechanical Engineering Research Lab.

    1999-07-01

    The present situation of electric power supply and energy consumption in Japan has made it necessary to develop a new absorption air conditioning system which has low electric energy consumption, uses natural organic refrigerants, and can work as a heat pump in winter. Estimating vapor and liquid equilibrium of new pairs of working fluids is prerequisite to developing the new absorption heat pump system. In this phase of the work, methods for estimating vapor and liquid equilibrium that take into account intermolecular force were investigated. Experimental and calculated data on natural organic materials mixtures were considered to find optimum candidates, and then a procedure for evaluation was chosen. Several candidate absorbents were selected that used isobutane and dimethyl ether as refrigerants. (orig.)

  16. Fluid approximation analysis of a call center model with time-varying arrivals and after-call work

    Directory of Open Access Journals (Sweden)

    Yosuke Kawai

    2015-12-01

    Full Text Available Important features to be included in queueing-theoretic models of the call center operation are multiple servers, impatient customers, time-varying arrival process, and operator’s after-call work (ACW. We propose a fluid approximation technique for the queueing model with these features by extending the analysis of a similar model without ACW recently developed by Liu and Whitt (2012. Our model assumes that the service for each quantum of fluid consists of a sequence of two stages, the first stage for the conversation with a customer and the second stage for the ACW. When the duration of each stage has exponential, hyperexponential or hypo-exponential distribution, we derive the time-dependent behavior of the content of fluid in each stage of service as well as that in the waiting room. Numerical examples are shown to illustrate the system performance for the cases in which the input rate and/or the number of servers vary in sinusoidal fashion as well as in adaptive ways and in stationary cases.

  17. Numerical Study on Heat Transfer Performance of PCHE With Supercritical CO{sub 2} as Working Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Sang Woo; Ngo, Ich-long; Byon, Chan [Yeungnam Univ., Gyeongsan (Korea, Republic of)

    2016-11-15

    The printed circuit heat exchanger (PCHE) is regarded as a promising candidate for advanced heat exchangers for the next-generation supercritical CO{sub 2} power generation owing to its high compactness and rigid structure. In this study, an innovative type of PCHE, in which the channel sizes for the heat source fluid and heat sink fluid are different, is considered for analysis. The thermal performance of the PCHE, with supercritical CO{sub 2} as the working fluid, is numerically analyzed. The results have shown that the thermal performance of the PCHE decreases monotonically when the channel size of either the heat source channel or the heat sink channel, because of the decreased flow velocity. On the other hand, the thermal performance of the PCHE is found to be almost independent of the spacing between the channels. In addition, it was found that the channel cross sectional shape has little effect on the thermal performance when the hydraulic diameter of the channel remains constant.

  18. Exergetic and thermodynamic comparison of R12 and R134a as vapour compression refrigeration working fluids

    Energy Technology Data Exchange (ETDEWEB)

    De Rossi, Filippo; Mastrullo, Rita; Mazzei, Pietro [Naples Univ. (Italy)

    1993-05-01

    A software package for both the computation of thermodynamic properties and the analysis of the usual vapour compression plant schemes is a useful tool for air conditioning and refrigeration researchers and manufacturers. At present, it could make an important contribution to the search for CFC substitutes; in fact, comparisons between two or more working fluids could be accomplished more easily. A program created by the authors is presented by means of some demonstrative diagrams referring to a comparison between the ''ozone killer'' R12 and its substitute R134a. An R134a exergy-enthalpy chart is also provided. (Author)

  19. Microgravity Fluids for Biology, Workshop

    Science.gov (United States)

    Griffin, DeVon; Kohl, Fred; Massa, Gioia D.; Motil, Brian; Parsons-Wingerter, Patricia; Quincy, Charles; Sato, Kevin; Singh, Bhim; Smith, Jeffrey D.; Wheeler, Raymond M.

    2013-01-01

    Microgravity Fluids for Biology represents an intersection of biology and fluid physics that present exciting research challenges to the Space Life and Physical Sciences Division. Solving and managing the transport processes and fluid mechanics in physiological and biological systems and processes are essential for future space exploration and colonization of space by humans. Adequate understanding of the underlying fluid physics and transport mechanisms will provide new, necessary insights and technologies for analyzing and designing biological systems critical to NASAs mission. To enable this mission, the fluid physics discipline needs to work to enhance the understanding of the influence of gravity on the scales and types of fluids (i.e., non-Newtonian) important to biology and life sciences. In turn, biomimetic, bio-inspired and synthetic biology applications based on physiology and biology can enrich the fluid mechanics and transport phenomena capabilities of the microgravity fluid physics community.

  20. Numerical simulation of nanofluids based on power-law fluids with flow and heat transfer

    Science.gov (United States)

    Li, Lin; Jiang, Yongyue; Chen, Aixin

    2017-04-01

    In this paper, we investigate the heat transfer of nanofluids based on power-law fluids and movement of nanoparticles with the effect of thermophoresis in a rotating circular groove. The velocity of circular groove rotating is a constant and the temperature on the wall is kept to be zero all the time which is different from the temperature of nanofluids in the initial time. The effects of thermophoresis and Brownian diffusion are considered in temperature and concentration equations, and it is assumed that the thermal conductivity of nanofluids is a function of concentration of nanoparticles. Based on numerical results, it can be found that nanofluids improve the process of heat transfer than base fluids in a rotating circular groove. The enhancement of heat transfer increases as the power law index of base fluids decreases.

  1. Study of methane solubility in oil base used in oil base drilling fluid; Estudo da solubilidade de metano em base oleo utilizada em fluido de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Carolina Teixeira da; Mariolani, Jose Ricardo Lenzi [Universidade Estadual de Campinas, SP (Brazil); Ribeiro, Paulo Roberto; Lomba, Rosana Fatima Teixeira; Bonet, Euclides Jose

    2004-07-01

    During drilling a well, it is necessary to prevent and control high pressurized zones because while drilling on those zones, could occur a kick if the formation pressure were higher then downhole pressure, allowing the entering of undesirables fluids from the formation to the wellbore. If the well is not controlled this kick could became a blowout, generating damages to the environment, to the equipment and the human life. When drilling using oil-based mud, the concern related to the well control would be higher due the gas solubility in the mud, which could make it hard to detect the kick, especially in deep and ultra deep waters. In this work we have studied the interaction between methane and organic liquids used in drilling fluids, and the measurement and analysis of the thermodynamic properties of those gas liquid mixtures. There have been measured parameters like the oil formation volume factor (FVF{sub o}), bubble pressure, solubility (Rs) and the density of the saturated liquid in function of methane mole fraction and temperature. The results have shown that the gas solubility, at downhole conditions and during kick circulation, is a factor very important to the safety during well drilling in deep and ultra deep waters. (author)

  2. Teaching statics of fluids in bioengineering: a multidisciplinary proposal based on competences

    Science.gov (United States)

    Alborch, A.; Puzzella, A.; Lopez, N.; Cabrera, L.; Zabala, A.; Demartini, H.

    2007-11-01

    The aim of this work is to share the findings of an educational experience undertaken by first-year university students of bioengineering, oriented towards the model of Competence-based Education. Different aspects on integrative education pursued in the subject goals are explicitly focused here by designing a strategy within a contextualized and multidisciplinary approach that combines knowledge from Physics, Chemistry and Biology. The topic chosen for the work is Static of Fluids, because it allows relating pressure to its biological effects on human beings. After evaluating a pre-test, new interrelated strategies are implemented. Due to the motivation audiovisuals generate in adolescents, we start showing an argumentative film entitled 'The Big Blue', and continue with different individual and/or group activities, finishing with a post-test to assess the development of the competences proposed. Results are encouraging as regards the level of specific competences acquired and, complementarily, basic and professional competences in general. Besides, the experience met expectations as regards student motivation, interest and commitment to learning, which ensured the path taken by the academicians by means of implementing innovative strategies.

  3. Teaching statics of fluids in bioengineering: a multidisciplinary proposal based on competences

    International Nuclear Information System (INIS)

    Alborch, A; Puzzella, A; Lopez, N; Cabrera, L; Zabala, A; Demartini, H

    2007-01-01

    The aim of this work is to share the findings of an educational experience undertaken by first-year university students of bioengineering, oriented towards the model of Competence-based Education. Different aspects on integrative education pursued in the subject goals are explicitly focused here by designing a strategy within a contextualized and multidisciplinary approach that combines knowledge from Physics, Chemistry and Biology. The topic chosen for the work is Static of Fluids, because it allows relating pressure to its biological effects on human beings. After evaluating a pre-test, new interrelated strategies are implemented. Due to the motivation audiovisuals generate in adolescents, we start showing an argumentative film entitled 'The Big Blue', and continue with different individual and/or group activities, finishing with a post-test to assess the development of the competences proposed. Results are encouraging as regards the level of specific competences acquired and, complementarily, basic and professional competences in general. Besides, the experience met expectations as regards student motivation, interest and commitment to learning, which ensured the path taken by the academicians by means of implementing innovative strategies

  4. Fluid-electrolyte shifts and thermoregulation - Rest and work in heat with head cooling

    Science.gov (United States)

    Greenleaf, J. E.; Van Beaumont, W.; Brock, P. J.; Montgomery, L. D.; Morse, J. T.; Shvartz, E.; Kravik, S.

    1980-01-01

    The effects of head cooling on thermoregulation and associated plasma fluid and electrolyte shifts during rest and submaximal exercise in the heat are investigated. Thermoregulatory responses and plasma volume were measured in four male subjects fitted with liquid-cooled neoprene headgear during 60 min of rest, 60 min of ergometer exercise at 45% maximal oxygen uptake and 30 min of recovery in the supine position at 40.1 C and 40% relative humidity. It is found that, compared to control responses, head cooling decreased thigh sweating and increased mean skin temperature at rest and attenuated increases in thigh sweating, heart rate, rectal temperature and ventilation during exercise. During recovery, cooling is observed to facilitate decreases in sweat rate, heart rate, rectal temperature and forearm blood flow and enhance the increase in average temperature. Cooling had no effect on plasma protein, osmotic or electrolyte shifts, and decreased plasma volume losses. The findings indicate the effectiveness of moderate head cooling for the improvement of human performance during exercise in heat.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-12

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

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

    Science.gov (United States)

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

    2016-07-01

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

  8. Thermal resistance of rotating closed-loop pulsating heat pipes: Effects of working fluids and internal diameters

    Directory of Open Access Journals (Sweden)

    Kammuang-Lue Niti

    2017-01-01

    Full Text Available The objective of this study was to experimentally investigate the effects of working fluids and internal diameters on the thermal resistance of rotating closed-loop pul¬sating heat pipes (RCLPHP. The RCLPHP were made of a copper tube with internal diameters of 1.50 mm and 1.78 mm, bent into the shape of a flower petal, and arranged into a circle with 11 turns. The evaporator section was located at the outer end of the tube bundle. R123, ethanol, and water were filled as the working fluids. The RCLPHP was rotated at centrifugal accelerations 0.5, 1, 3, 5, 10, and 20 times of the gravitational acceleration considered at the connection between the evaporator and the condenser sections. The heat input was varied from 30 W to 50 W, and then to 100 W, 150 W, and 200 W. It can be concluded that when the latent heat of evaporation increases, the pressure difference between the evaporator and the condenser sections decreases, and the thermal resistance increases. Moreover, when the internal diameter increases, the driving force increases and the frictional force proportionally decreases, or the Karman number increases, and the thermal resistance decreases.

  9. HIDE working groups: synchrotron based system: summary

    International Nuclear Information System (INIS)

    Barton, M.Q.

    1978-01-01

    A brief overview is given of the work resulting from a one-week workshop on the use of synchrotrons in heavy ion fusion, i.e., a Heavy Ion Demonstration Experiment (HIDE). Topics discussed concerned the number of beams on target, space charge limitations, choice of ion charge state, and areas identified as needing further work

  10. Neural mechanisms of interference control in working memory: effects of interference expectancy and fluid intelligence.

    Directory of Open Access Journals (Sweden)

    Gregory C Burgess

    2010-09-01

    Full Text Available A critical aspect of executive control is the ability to limit the adverse effects of interference. Previous studies have shown activation of left ventrolateral prefrontal cortex after the onset of interference, suggesting that interference may be resolved in a reactive manner. However, we suggest that interference control may also operate in a proactive manner to prevent effects of interference. The current study investigated the temporal dynamics of interference control by varying two factors - interference expectancy and fluid intelligence (gF - that could influence whether interference control operates proactively versus reactively.A modified version of the recent negatives task was utilized. Interference expectancy was manipulated across task blocks by changing the proportion of recent negative (interference trials versus recent positive (facilitation trials. Furthermore, we explored whether gF affected the tendency to utilize specific interference control mechanisms. When interference expectancy was low, activity in lateral prefrontal cortex replicated prior results showing a reactive control pattern (i.e., interference-sensitivity during probe period. In contrast, when interference expectancy was high, bilateral prefrontal cortex activation was more indicative of proactive control mechanisms (interference-related effects prior to the probe period. Additional results suggested that the proactive control pattern was more evident in high gF individuals, whereas the reactive control pattern was more evident in low gF individuals.The results suggest the presence of two neural mechanisms of interference control, with the differential expression of these mechanisms modulated by both experimental (e.g., expectancy effects and individual difference (e.g., gF factors.

  11. Purification of bentonitics of the city Cubati-PB to obtaining organoclays for use in oil-based drilling fluids

    International Nuclear Information System (INIS)

    Costa, J.M.R.; Vitorino, I.J.F.; Silva, I.A.; Neves, G.A.; Ferreira, H.C.

    2011-01-01

    In Boa Vista, PB, are located deposits of bentonite clays commonly used in the preparation of drilling fluids. The disorderly exploitation of the deposits of Boa Vista is causing the depletion of these clays, which will cause a very serious problem for the national oil industry. This work aims to characterize new deposits of bentonite clays Cubati, PB, for the development of organoclay from its refining using a hydrocyclone for use in oil based drilling fluids. The characterization of samples of the clays was performed through the techniques: AG, XRD, EDX, TGA and DTA. The characterization is typical of bentonite for the purification process was determined the best configuration of the hydrocyclone, and the environment organic diesel fuel, the best affinity was obtained with clays organophilizated with surfactant Praepagen WB. (author)

  12. Water drilling fluids: evaluation of lubricity and clay swelling control; Fluidos de perfuracao a base de agua: avaliacao de lubricidade e controle de inchamento de argilas

    Energy Technology Data Exchange (ETDEWEB)

    Felix, Thiago de Freitas; Arruda, Jefferson Teixeira; Medeiros, Ana Catarina; Garcia, Rosangela Balaban [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    During the oil well drilling, drilling fluids are used in order to transport the cuttings until the surface. This fluid is also responsible for the mechanical sustentation of the well walls, the control of undesirable production of fluids in the formation, the lubricity and the cooling of the bit. The drilling fluids based on water are extensively applied due to their lower cost, thermal stability, biodegradability, easiness of pumping and treatment, resulting in smaller environmental impacts. However, some situations, such as hydrophilic shale drilling, request the use of additives to avoid the hydration of them and, consequently, the tool imprisonment or migration (filtration) of the drilling fluids into the rock. The goal of this work was to develop and test formulations of water-base drilling fluids with high capacity of inhibition of clay swelling and lubricity, obtaining drillings with larger penetration rate and calipers without enlargements. The results showed that the appropriate combination of commonly used commercial products can promote the obtaining of fluids with equal or better performance than those used by world companies. (author)

  13. A magnetorheological fluid-based multifunctional haptic device for vehicular instrument controls

    International Nuclear Information System (INIS)

    Han, Young-Min; Kim, Chan-Jung; Choi, Seung-Bok

    2009-01-01

    This paper presents control performances of a magnetorheological (MR) fluid-based multifunctional haptic device which is applicable to vehicular instrument controls. By combining in-vehicle functions into a single device, the proposed haptic device can transmit various reflection forces for each comfort function to a driver without requiring the driver's visual attention. As a multifunctional haptic device, a MR knob is proposed in this work and then devised to be capable of both rotary and push motions with a single knob. Under consideration of the spatial limitations of vehicle dashboards, design parameters are optimally determined by finite element analysis, and the objective function is to maximize a relative control torque. The proposed haptic device is then manufactured, and in-vehicle comfort functions are constructed in a virtual environment which makes the functions to communicate with the haptic device. Subsequently, a feed-forward controller using torque/force maps is formulated for the force tracking control. Control performances such as reflection force of the haptic device are experimentally evaluated via the torque/force map-based feed-forward controller

  14. Curvature computation in volume-of-fluid method based on point-cloud sampling

    Science.gov (United States)

    Kassar, Bruno B. M.; Carneiro, João N. E.; Nieckele, Angela O.

    2018-01-01

    This work proposes a novel approach to compute interface curvature in multiphase flow simulation based on Volume of Fluid (VOF) method. It is well documented in the literature that curvature and normal vector computation in VOF may lack accuracy mainly due to abrupt changes in the volume fraction field across the interfaces. This may cause deterioration on the interface tension forces estimates, often resulting in inaccurate results for interface tension dominated flows. Many techniques have been presented over the last years in order to enhance accuracy in normal vectors and curvature estimates including height functions, parabolic fitting of the volume fraction, reconstructing distance functions, coupling Level Set method with VOF, convolving the volume fraction field with smoothing kernels among others. We propose a novel technique based on a representation of the interface by a cloud of points. The curvatures and the interface normal vectors are computed geometrically at each point of the cloud and projected onto the Eulerian grid in a Front-Tracking manner. Results are compared to benchmark data and significant reduction on spurious currents as well as improvement in the pressure jump are observed. The method was developed in the open source suite OpenFOAM® extending its standard VOF implementation, the interFoam solver.

  15. Structure of nanoparticles in transformer oil-based magnetic fluids, anisotropy of acoustic attenuation

    International Nuclear Information System (INIS)

    Kúdelčík, Jozef; Bury, Peter; Kopčanský, Peter; Timko, Milan

    2015-01-01

    The anisotropy of acoustic attenuation in transformer oil-based magnetic fluids upon the external magnetic field was studied to discover the structure of nanoparticles. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles leads to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids and the concentration of nanoparticles also have very important influence on the structural changes. The measurement of the dependence of the acoustic attenuation on the angle between the magnetic field direction and acoustic wave vector (anisotropy) can give the useful information about the structure of magnetic nanoparticles formations. In the present, the results of anisotropy measurements of the transformer oil-based magnetic fluids are described and using appropriate theory the basic parameters of clusters are calculated. On the basis of the performed calculations, the proportion of the acoustic wave energy used for excitation of the translational and rotational degrees of freedom was also established. - Highlights: • Nanoparticles formation in transformer oil-based magnetic fluids was investigated. • The anisotropy acoustic spectroscopy as the method of investigation was used. • The external conditions on the structure of magnetic fluids were studied. • The structure parameters using suitable theoretical model were determined

  16. Structure of nanoparticles in transformer oil-based magnetic fluids, anisotropy of acoustic attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Kúdelčík, Jozef, E-mail: kudelcik@fyzika.uniza.sk [Department of Physics, University of Žilina, Univerzitná 1, 010 01 Žilina (Slovakia); Bury, Peter [Department of Physics, University of Žilina, Univerzitná 1, 010 01 Žilina (Slovakia); Kopčanský, Peter; Timko, Milan [Department of Magnetism, IEP SAS, Watsonova 47, 040 01 Košice (Slovakia)

    2015-08-15

    The anisotropy of acoustic attenuation in transformer oil-based magnetic fluids upon the external magnetic field was studied to discover the structure of nanoparticles. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles leads to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids and the concentration of nanoparticles also have very important influence on the structural changes. The measurement of the dependence of the acoustic attenuation on the angle between the magnetic field direction and acoustic wave vector (anisotropy) can give the useful information about the structure of magnetic nanoparticles formations. In the present, the results of anisotropy measurements of the transformer oil-based magnetic fluids are described and using appropriate theory the basic parameters of clusters are calculated. On the basis of the performed calculations, the proportion of the acoustic wave energy used for excitation of the translational and rotational degrees of freedom was also established. - Highlights: • Nanoparticles formation in transformer oil-based magnetic fluids was investigated. • The anisotropy acoustic spectroscopy as the method of investigation was used. • The external conditions on the structure of magnetic fluids were studied. • The structure parameters using suitable theoretical model were determined.

  17. A volume of fluid method based on multidimensional advection and spline interface reconstruction

    International Nuclear Information System (INIS)

    Lopez, J.; Hernandez, J.; Gomez, P.; Faura, F.

    2004-01-01

    A new volume of fluid method for tracking two-dimensional interfaces is presented. The method involves a multidimensional advection algorithm based on the use of edge-matched flux polygons to integrate the volume fraction evolution equation, and a spline-based reconstruction algorithm. The accuracy and efficiency of the proposed method are analyzed using different tests, and the results are compared with those obtained recently by other authors. Despite its simplicity, the proposed method represents a significant improvement, and compares favorably with other volume of fluid methods as regards the accuracy and efficiency of both the advection and reconstruction steps

  18. The neural bases of orthographic working memory

    Directory of Open Access Journals (Sweden)

    Jeremy Purcell

    2014-04-01

    First, these results reveal a neurotopography of OWM lesion sites that is well-aligned with results from neuroimaging of orthographic working memory in neurally intact participants (Rapp & Dufor, 2011. Second, the dorsal neurotopography of the OWM lesion overlap is clearly distinct from what has been reported for lesions associated with either lexical or sublexical deficits (e.g., Henry, Beeson, Stark, & Rapcsak, 2007; Rapcsak & Beeson, 2004; these have, respectively, been identified with the inferior occipital/temporal and superior temporal/inferior parietal regions. These neurotopographic distinctions support the claims of the computational distinctiveness of long-term vs. working memory operations. The specific lesion loci raise a number of questions to be discussed regarding: (a the selectivity of these regions and associated deficits to orthographic working memory vs. working memory more generally (b the possibility that different lesion sub-regions may correspond to different components of the OWM system.

  19. Work-based resources as moderators of the relationship between work hours and satisfaction with work-family balance.

    Science.gov (United States)

    Valcour, Monique

    2007-11-01

    This study reports an investigation of the relationships of work hours, job complexity, and control over work time to satisfaction with work-family balance. Based on data from a sample of 570 telephone call center representatives, a moderated hierarchical regression analysis revealed that work hours were negatively related to satisfaction with work-family balance, consistent with the resource drain perspective. Job complexity and control over work time were positively associated with satisfaction with work-family balance. Control over work time moderated the relationship such that as work hours rose, workers with low control experienced a decline in work-family balance satisfaction, while workers with high control did not. Results encourage greater research attention to work characteristics, such as job complexity and control over work time, and skills that represent resources useful to the successful integration of work and family demands. (c) 2007 APA

  20. Methods of increasing net work output of organic Rankine cycles for low-grade waste heat recovery with a detailed analysis using a zeotropic working fluid mixture and scroll expander

    Science.gov (United States)

    Woodland, Brandon Jay

    performance to cost ratio of this machine lends significant credence to the economic viability of small-scale, low-temperature ORCs. The experimental campaign covered two heat source temperatures, the full range of pump and expander speeds, a full range of heat source and heat sink fluid flow rates, and various charge levels for the three working fluids. This resulted in 366 steady-state measurements. The steady state measurements are used to develop a detailed ORC model. The model is based on multi-fluid performance maps for the pump and expander and a robust moving-boundary heat exchanger model. It is validated against the measured data and predicts the net power output of the tested ORC with a mean absolute percent error of 7.16%. Comparisons made with the detailed model confirm the predictions of the design-stage model. Using a conservative estimate of the condenser fan power, 19.1% improvement of the ZRC over the baseline ORC is indicated for a source temperature of 80 °C. For a 100 °C source temperature, 13.8% improvement is indicated. A key feature of the detailed ORC model is that it calculates the charge inventory of the working fluid in each heat exchanger and line set. Total system charge can also be specified as a model input. The model can represent the total charge well for R134a at low measured charge levels. As the measured charge level increases, the model becomes less accurate. Reasons for the deviation of the model at higher charge are investigated. It is expected that a charge tuning scheme could be employed to improve the accuracy of model-predicted charge.

  1. A heterogeneous system based on GPU and multi-core CPU for real-time fluid and rigid body simulation

    Science.gov (United States)

    da Silva Junior, José Ricardo; Gonzalez Clua, Esteban W.; Montenegro, Anselmo; Lage, Marcos; Dreux, Marcelo de Andrade; Joselli, Mark; Pagliosa, Paulo A.; Kuryla, Christine Lucille

    2012-03-01

    Computational fluid dynamics in simulation has become an important field not only for physics and engineering areas but also for simulation, computer graphics, virtual reality and even video game development. Many efficient models have been developed over the years, but when many contact interactions must be processed, most models present difficulties or cannot achieve real-time results when executed. The advent of parallel computing has enabled the development of many strategies for accelerating the simulations. Our work proposes a new system which uses some successful algorithms already proposed, as well as a data structure organisation based on a heterogeneous architecture using CPUs and GPUs, in order to process the simulation of the interaction of fluids and rigid bodies. This successfully results in a two-way interaction between them and their surrounding objects. As far as we know, this is the first work that presents a computational collaborative environment which makes use of two different paradigms of hardware architecture for this specific kind of problem. Since our method achieves real-time results, it is suitable for virtual reality, simulation and video game fluid simulation problems.

  2. CFD Analysis of a Centrifugal Pump with Supercritical Carbon Dioxide as a Working Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Gu; Lee, Jeong Ik; Ahn, Yoonhan; Lee, Jekyoung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Cha, Jae Eun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Addad, Yacine [Khalifa Univ. of Science Technology and Research, Abu Dhabi (United Arab Emirates)

    2013-05-15

    The research team is conducting a S-CO{sub 2} pump experiment to obtain fundamental data for the advanced pump design and measure the overall performance of the pump near the critical point. The S-CO{sub 2} pump testing loop configuration is similar to SNL and JAEA testing loop while the operating conditions and focus of experiment are different from other test facilities. This paper presents the methodology of a 3-dimensional flow analysis for the S-CO{sub 2} pump by using the commercial CFD code. In Figure 2, the results at the 1.5kg/s mass flow rate seems to be close agreement between the CFD efficiency and S-CO{sub 2} test results. In the low mass flow rate of 1.0kg/s, CFD predicted 17∼25% higher efficiency than the test result. In the real test facility, the steel structure of pump is not an adiabatic wall and also the mechanical losses such as suction, blade loading and leakage exist in the pump. The reason why CFD analysis showed higher pump efficiency at the low mass flow is the above mentioned losses were excluded from the model. However, as the mass flow rate increases these have less effect on the efficiency. If the heat transfer through the structure and pump losses are applied in the analysis, other losses can be estimated. From the S-CO{sub 2} pump experiment, more data will be obtained and compared to the CFD analyses under the methodology presented in this paper. After the fluid behavior in the pump are well understood, these analysis results will be used for optimizing impeller for advanced S-CO{sub 2} compressor design in the future. However, it is very encouraging that even at very small mass flow rate the efficiency of S-CO{sub 2} pump near the critical point operation is very high compared to the manufacturer water test. The reason behind such phenomenon will be more carefully studied in the future.

  3. Experimental determination of nanofluid specific heat with SiO2 nanoparticles in different base fluids

    Science.gov (United States)

    Akilu, S.; Baheta, A. T.; Sharma, K. V.; Said, M. A.

    2017-09-01

    Nanostructured ceramic materials have recently attracted attention as promising heat transfer fluid additives owing to their outstanding heat storage capacities. In this paper, experimental measurements of the specific heats of SiO2-Glycerol, SiO2-Ethylene Glycol, and SiO2-Glycerol/Ethylene Glycol mixture 60:40 ratio (by mass) nanofluids with different volume concentrations of 1.0-4.0% have been carried out using differential scanning calorimeter at temperatures of 25 °C and 50 °C. Experimental results indicate lower specific heat capacities are found with SiO2 nanofluids compared to their respective base fluids. The specific heat was decreasing with the increase of concentration, and this decrement depends on upon the type of the base fluid. It is observed that temperature has a positive impact on the specific heat capacity. Furthermore, the experimental values were compared with the theoretical model predictions, and a satisfactory agreement was established.

  4. FluidCam 1&2 - UAV-based Fluid Lensing Instruments for High-Resolution 3D Subaqueous Imaging and Automated Remote Biosphere Assessment of Reef Ecosystems

    Science.gov (United States)

    Chirayath, V.; Instrella, R.

    2016-02-01

    We present NASA ESTO FluidCam 1 & 2, Visible and NIR Fluid-Lensing-enabled imaging payloads for Unmanned Aerial Vehicles (UAVs). Developed as part of a focused 2014 earth science technology grant, FluidCam 1&2 are Fluid-Lensing-based computational optical imagers designed for automated 3D mapping and remote sensing of underwater coastal targets from airborne platforms. Fluid Lensing has been used to map underwater reefs in 3D in American Samoa and Hamelin Pool, Australia from UAV platforms at sub-cm scale, which has proven a valuable tool in modern marine research for marine biosphere assessment and conservation. We share FluidCam 1&2 instrument validation and testing results as well as preliminary processed data from field campaigns. Petabyte-scale aerial survey efforts using Fluid Lensing to image at-risk reefs demonstrate broad applicability to large-scale automated species identification, morphology studies and reef ecosystem characterization for shallow marine environments and terrestrial biospheres, of crucial importance to improving bathymetry data for physical oceanographic models and understanding climate change's impact on coastal zones, global oxygen production, carbon sequestration.

  5. Acoustic investigation of structure of magnetic fluids based on transformer oil mogul

    International Nuclear Information System (INIS)

    Kudelcik, J.; Bury, P.; Kopcansky, P.; Timko, M.

    2013-01-01

    In this paper the authors study the influence of temperature on the changes of the acoustic attenuation in magnetic fluids based on transformer oil MOGUL caused by an external magnetic field measured. The influences of both magnetic field and temperature on the structures of investigated magnetic fluids based on the transformer oil MOGUL were observed using acoustic spectroscopy. The effect of external magnetic field on the creation of clusters of nanoparticles in magnetic fluids was confirmed and their influence on the development of attenuation was described. In this type of magnetic fluid complicated structures of clusters at magnetic field over 100 mT are created. These structures are than at higher magnetic field almost stable. This state of equilibrium is not function of time. Measurements also confirmed that the lifetime of these structures or clusters is very short. The further investigation of the time and temperature dependences of the acoustic attenuation on the magnetic field at different concentrations of magnetic nanoparticles and various direction of magnetic field are necessary to understand all processes in this magnetic fluid. (authors)

  6. Dispersability of Carbon Nanotubes in Biopolymer-Based Fluids

    Directory of Open Access Journals (Sweden)

    Franco Tardani

    2015-01-01

    Full Text Available In this review the dispersability of carbon nanotubes in aqueous solutions containing proteins, or nucleic acids, is discussed. Data reported previously are complemented by unpublished ones. In the mentioned nanotube-based systems several different phases are observed, depending on the type and concentration of biopolymer, as well as the amount of dispersed nanotubes. The phase behavior depends on how much biopolymers are adsorbing, and, naturally, on the molecular details of the adsorbents. Proper modulation of nanotube/biopolymer interactions helps switching between repulsive and attractive regimes. Dispersion or phase separation take place, respectively, and the formation of liquid crystalline phases or gels may prevail with respect to dispersions. We report on systems containing ss-DNA- and lysozyme-stabilized nanotubes, representative of different organization modes. In the former case, ss-DNA rolls around CNTs and ensures complete coverage. Conversely, proteins randomly and non-cooperatively adsorb onto nanotubes. The two functionalization mechanisms are significantly different. A fine-tuning of temperature, added polymer, pH, and/or ionic strength conditions induces the formation of a given supra-molecular organization mode. The biopolymer physico-chemical properties are relevant to induce the formation of different phases made of carbon nanotubes.

  7. Working memory components that predict word problem solving: Is it merely a function of reading, calculation, and fluid intelligence?

    Science.gov (United States)

    Fung, Wenson; Swanson, H Lee

    2017-07-01

    The purpose of this study was to assess whether the differential effects of working memory (WM) components (the central executive, phonological loop, and visual-spatial sketchpad) on math word problem-solving accuracy in children (N = 413, ages 6-10) are completely mediated by reading, calculation, and fluid intelligence. The results indicated that all three WM components predicted word problem solving in the nonmediated model, but only the storage component of WM yielded a significant direct path to word problem-solving accuracy in the fully mediated model. Fluid intelligence was found to moderate the relationship between WM and word problem solving, whereas reading, calculation, and related skills (naming speed, domain-specific knowledge) completely mediated the influence of the executive system on problem-solving accuracy. Our results are consistent with findings suggesting that storage eliminates the predictive contribution of executive WM to various measures Colom, Rebollo, Abad, & Shih (Memory & Cognition, 34: 158-171, 2006). The findings suggest that the storage component of WM, rather than the executive component, has a direct path to higher-order processing in children.

  8. HIDE working groups. A. Synchrotron based system

    International Nuclear Information System (INIS)

    Barton, M.Q.

    1977-01-01

    A summary is given of a week's discussions on an ion source to target scenario for a synchrotron for heavy ion fusion. Topics considered include: the number of beams on the target; beam dynamics; and a number of areas explicitly identified as needing further work

  9. A new class of variable capacitance generators based on the dielectric fluid transducer

    Science.gov (United States)

    Duranti, Mattia; Righi, Michele; Vertechy, Rocco; Fontana, Marco

    2017-11-01

    This paper introduces the novel concept of dielectric fluid transducer (DFT), which is an electrostatic variable capacitance transducer made by compliant electrodes, solid dielectrics and a dielectric fluid with variable volume and/or shape. The DFT can be employed in actuator mode and generator mode. In this work, DFTs are studied as electromechanical generators able to convert oscillating mechanical energy into direct current electricity. Beside illustrating the working principle of dielectric fluid generators (DFGs), we introduce different architectural implementations and provide considerations on limitations and best practices for their design. Additionally, the proposed concept is demonstrated in a preliminary experimental test campaign conducted on a first DFG prototype. During experimental tests a maximum energy per cycle of 4.6 {mJ} and maximum power of 0.575 {mW} has been converted, with a conversion efficiency up to 30%. These figures correspond to converted energy densities of 63.8 {mJ} {{{g}}}-1 with respect to the displaced dielectric fluid and 179.0 {mJ} {{{g}}}-1 with respect to the mass of the solid dielectric. This promising performance can be largely improved through the optimization of device topology and dimensions, as well as by the adoption of more performing conductive and dielectric materials.

  10. Comparison of CFD results for a supercritical CO{sub 2} compressor with compressible and incompressible working fluids

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Gu; Baik, Seungjoon; Cho, Seong Kuk; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of); Kwon, Jinsu [Hanyang University, Seoul (Korea, Republic of)

    2015-10-15

    enhance understand how S-CO{sub 2} can behave from conventional working fluid.

  11. Fluid transport due to nonlinear fluid-structure interaction

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    1997-01-01

    This work considers nonlinear fluid-structure interaction for a vibrating pipe containing fluid. Transverse pipe vibrations will force the fluid to move relative to the pipe creating unidirectional fluid flow towards the pipe end. The fluid flow induced affects the damping and the stiffness...... of the pipe. The behavior of the system in response to lateral resonant base excitation is analysed numerically and by the use of a perturbation method (multiple scales). Exciting the pipe in the fundamental mode of vibration seems to be most effective for transferring energy from the shaker to the fluid......, whereas higher modes of vibration can be used to transport fluid with pipe vibrations of smaller amplitude. The effect of the nonlinear geometrical terms is analysed and these terms are shown to affect the response for higher modes of vibration. Experimental investigations show good agreement...

  12. A dynamic organic Rankine cycle using a zeotropic mixture as the working fluid with composition tuning to match changing ambient conditions

    International Nuclear Information System (INIS)

    Collings, Peter; Yu, Zhibin; Wang, Enhua

    2016-01-01

    Highlights: • A dynamic ORC using a zeotropic mixture with composition tuning is proposed. • The working principle is verified theoretically, based on a thermodynamic model. • Improvements in the resultant power plant’s annual power production are analysed. • The economic benefits have been demonstrated by an economic analysis. - Abstract: Air-cooled condensers are widely used for Organic Rankine Cycle (ORC) power plants where cooling water is unavailable or too costly, but they are then vulnerable to changing ambient air temperatures especially in continental climates, where the air temperature difference between winter and summer can be over 40 °C. A conventional ORC system using a single component working fluid has to be designed according to the maximum air temperature in summer and thus operates far from optimal design conditions for most of the year, leading to low annual average efficiencies. This research proposes a novel dynamic ORC that uses a binary zeotropic mixture as the working fluid, with mechanisms in place to adjust the mixture composition dynamically during operation in response to changing heat sink conditions, significantly improving the overall efficiency of the plant. The working principle of the dynamic ORC concept is analysed. The case study results show that the annual average thermal efficiency can be improved by up to 23% over a conventional ORC when the heat source is 100 °C, while the evaluated increase of the capital cost is less than 7%. The dynamic ORC power plants are particularly attractive for low temperature applications, delivering shorter payback periods compared to conventional ORC systems.

  13. Morphological analysis of mouse lungs after treatment with magnetite-based magnetic fluid stabilized with DMSA

    International Nuclear Information System (INIS)

    Pereira Garcia, Monica; Miranda Parca, Renata; Braun Chaves, Sacha; Paulino Silva, Luciano; Djalma Santos, Antonio; Guerrero Marques Lacava, Zulmira; Cesar Morais, Paulo; Azevedo, Ricardo Bentes

    2005-01-01

    Mouse lungs injected with magnetic fluids based on magnetite nanoparticles stabilized by 2,3-dimercaptosuccinic acid were studied. We observed clusters of magnetic nanoparticles inside blood vessels, within the organ parenchyma and cells, as well as increased numbers of leukocytes in the organ. Both the particle concentration and organ inflammation diminished in a time-dependent manner

  14. investigation into the use of water based brake fluid for light loads

    African Journals Online (AJOL)

    2012-12-19

    Dec 19, 2012 ... The dry boiling point of glycol based fluid seldom exceeds 304°C . ... by means of a brake, the kinetic energy must be absorbed (Shigley, ... Similarly, when the moving body is broughtto rest after the braking, then v2 is zero.

  15. Computational Fluid Dynamics based Fault Simulations of a Vertical Axis Wind Turbines

    International Nuclear Information System (INIS)

    Park, Kyoo-seon; Asim, Taimoor; Mishra, Rakesh

    2012-01-01

    Due to depleting fossil fuels and a rapid increase in the fuel prices globally, the search for alternative energy sources is becoming more and more significant. One of such energy source is the wind energy which can be harnessed with the use of wind turbines. The fundamental principle of wind turbines is to convert the wind energy into first mechanical and then into electrical form. The relatively simple operation of such turbines has stirred the researchers to come up with innovative designs for global acceptance and to make these turbines commercially viable. Furthermore, the maintenance of wind turbines has long been a topic of interest. Condition based monitoring of wind turbines is essential to maintain continuous operation of wind turbines. The present work focuses on the difference in the outputs of a vertical axis wind turbine (VAWT) under different operational conditions. A Computational Fluid Dynamics (CFD) technique has been used for various blade configurations of a VAWT. The results indicate that there is significant degradation in the performance output of wind turbines as the number of blades broken or missing from the VAWT increases. The study predicts the faults in the blades of VAWTs by monitoring its output.

  16. Optimization of Cycle and Expander Design of an Organic Rankine Cycle Unit using Multi-Component Working Fluids

    DEFF Research Database (Denmark)

    Meroni, Andrea; Andreasen, Jesper Graa; Pierobon, Leonardo

    2016-01-01

    Organic Rankine cycle (ORC) power systems represent at-tractive solutions for power conversion from low temperatureheat sources, and the use of these power systems is gaining increasing attention in the marine industry. This paper proposesthe combined optimal design of cycle and expander...... for an organic Rankine cycle unit utilizing waste heat from low temperature heat sources. The study addresses a case where the minimum temperature of the heat source is constrained and a case where no constraint is imposed. The former case is the wasteheat recovery from jacket cooling water of a marine diesel...... engine onboard a large ship, and the latter is representative of a low-temperature geothermal, solar or waste heat recovery application. Multi-component working fluids are investigated, as they allow improving the match between the temperature pro-files in the heat exchangers and, consequently, reducing...

  17. Photosynthetic and Ultrastructure Parameters of Maize Plants are Affected During the Phyto-Rhizoremediation Process of Degraded Metal Working Fluids.

    Science.gov (United States)

    Grijalbo, Lucía; Gutierrez Mañero, Francisco Javier; Fernandez-Pascual, Mercedes; Lucas, Jose Antonio

    2015-01-01

    A phyto-rhizoremediation system using corn and esparto fiber as rooting support to remediate degraded metal working fluids (dMWFs) has been developed in the present study. In order to improve the process, plants were inoculated at the root level with bacteria either individually, and with a consortium of strains. All strains used were able to grow with MWFs. The results show that this system significantly lowers the Chemical Oxygen Demand below legal limits within 5 days. However, results were only improved with the bacterial consortium. Despite the effectiveness of the phyto-rhizoremediation process, plants are damaged at the photosynthetic level according to the photosynthetic parameters measured, as well as at the ultrastructure of the vascular cylinder and the Bundle Sheath Cells. Interestingly, the bacterial inoculation protects against this damage. Therefore, it seems that that the inoculation with bacteria can protect the plants against these harmful effects.

  18. Optimization of organo clay production for applications in based oil drilling fluid; Otimizacao do processo de organofilizacao para aplicacoes em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Heber S.; Martins, Alice B.; Costa, Danubia L. da; Ferreira, Heber C.; Neves, Gelmires de A.; Melo, Tomas J.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Teixeira Neto, Erico [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2008-07-01

    The organophilic clays are widely used as an agent dispersed in the composition of oil based drilling fluids. The organophilic clays are gotten from bentonite clays treated, in watery way, with ionic surfactants, that are adsorbed in the surface of interlayer of the clays, re-covered them with a organic layer. A fundamental stage of production of the organophilic clays is the dispersion of bentonite clays, in way that variables like: speed of agitation, temperature and time of cure, influences directly in plastic and apparent viscosities of these dispersions, together with other variables of organophilization process, like, temperature and time of cure of organophilization, has direct influence in efficiency of the organophilization process. This work considers a study of these variable, using bentonite clays: Brasgel PA{sup R} and Cloisite Na{sup +R}, treated with the ionic surfactant Praepagem WB{sup R}. The organophilic clays gotten had been characterized by rays X diffraction, Foster's swelling, and the results were compared with the commercial organophilic clay VG-69{sup R}, industrially treated with ionic surfactant. Viscosities plastic and apparent of the dispersions had been measured in the midst of organic dispersant diesel oil used to obtain the oil based drilling fluids. Preliminary results of Foster's swelling and preparation of fluids show that the clays have affinity with the means liquid organic dispersants, and the fluids meet specifications of PETROBRAS (N-22581-1997 and N-2259 to 1997) for use in the of diesel oil based drilling fluids. (author)

  19. Fabrication and characterization of mesoporous TiO2/polypyrrole-based nanocomposite for electrorheological fluid

    International Nuclear Information System (INIS)

    Wei Chuan; Zhu Yihua; Jin Yi; Yang Xiaoling; Li Chunzhong

    2008-01-01

    Mesoporous TiO 2 /polypyrrole (PPy)-based nanocomposite for electrorheological fluid was synthesized through one-pot method. By exploiting the combination conductivity of PPy and high dielectric constant of TiO 2 , the ER fluid exhibited an enhanced effect. The shear stress was 3.3 times as high as that of mesoporous TiO 2 . Powder X-ray diffraction (XRD), TEM and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize the as-made samples. Using a modified rotational viscometer, the electrorheological effect was measured. Dielectric spectra were also given to explain the mechanism

  20. Studying effect of carrier fluid viscosity in magnetite based ferrofluids using optical tweezers

    Science.gov (United States)

    Savitha, S.; Iyengar, Shruthi S.; Ananthamurthy, Sharath; Bhattacharya, Sarbari

    2018-02-01

    Ferrofluids with varying viscosities of carrier fluids have been prepared with magnetite (Fe3O4) nanoparticles. The nanoparticles were synthesized by chemical co-precipitation and characterized using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). They were found to be nearly spherical in shape with an almost uniform size of 13nm. The superparamagnetic nature of the water based ferrofluids at room temperature was established by SQUID magnetometry. Dynamic light scattering (DLS) was carried out to establish the size of the nanoparticle clusters in the ferrofluids synthesized. The results indicate an increase in cluster size with increase in carrier fluid viscosity. This is supported by results from Raman Spectroscopy. A further attempt to characterise these ferrofluids was made by studying the behaviour of well characterised non-magnetic micron sized probes that are optically trapped while suspended in the ferrofluid. An increase in carrier fluid viscosity results in a decrease in corner frequency when only the carrier fluid is used as the suspending medium. When the magnetic component is also present the corner frequency is higher than with just the carrier fluid. This relative increase happens at all laser powers at the trapping plane. This trend is also found to be independent of the size and material of the probe particle. Comparisons of various parameters that influence optical trapping lead us to believe that the enhancement could be due to a directed motion of the magnetic clusters in the presence of an optical trap.

  1. Dielectrophoresis-magnetophoresis force driven magnetic nanoparticle movement in transformer oil based magnetic fluids.

    Science.gov (United States)

    Lee, Jong-Chul; Lee, Sangyoup

    2013-09-01

    Magnetic fluid is a stable colloidal mixture contained magnetic nanoparticles coated with a surfactant. Recently, it was found that the fluid has properties to increase heat transfer and dielectric characteristics due to the added magnetic nanoparticles in transformer oils. The magnetic nanoparticles in the fluid experience an electrical force directed toward the place of maximum electric field strength when the electric field is applied. And when the external magnetic field is applied, the magnetic nanoparticles form long chains oriented along the direction of the field. The behaviors of magnetic nanoparticles in both the fields must play an important role in changing the heat transfer and dielectric characteristics of the fluids. In this study, we visualized the movement of magnetic nanoparticles influenced by both the fields applied in-situ. It was found that the magnetic nanoparticles travel in the region near the electrode by the electric field and form long chains along the field direction by the magnetic field. It can be inferred that the movement of magnetic nanoparticles appears by both the fields, and the breakdown voltage of transformer oil based magnetic fluids might be influenced according to the dispersion of magnetic nanoparticles.

  2. A vorticity based approach to handle the fluid-structure interaction problems

    Energy Technology Data Exchange (ETDEWEB)

    Farahbakhsh, Iman; Ghassemi, Hassan [Department of Ocean Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sabetghadam, Fereidoun, E-mail: i.farahbakhsh@aut.ac.ir [Mechanical and Aerospace Engineering Department, Science and Research Branch, Islamic Azad University (IAU), Tehran (Iran, Islamic Republic of)

    2016-02-15

    A vorticity based approach for the numerical solution of the fluid-structure interaction problems is introduced in which the fluid and structure(s) can be viewed as a continuum. Retrieving the vorticity field and recalculating a solenoidal velocity field, specially at the fluid-structure interface, are the kernel of the proposed algorithm. In the suggested method, a variety of constitutive equations as a function of left Cauchy–Green deformation tensor can be applied for modeling the structure domain. A nonlinear Mooney–Rivlin and Saint Venant–Kirchhoff model are expressed in terms of the left Cauchy–Green deformation tensor and the presented method is able to model the behavior of a visco-hyperelastic structure in the incompressible flow. Some numerical experiments, with considering the neo-Hookean model for structure domain, are executed and the results are validated via the available results from literature. (paper)

  3. An EQT-based cDFT approach for a confined Lennard-Jones fluid mixture

    Energy Technology Data Exchange (ETDEWEB)

    Motevaselian, M. H.; Mashayak, S. Y.; Aluru, N. R., E-mail: aluru@illinois.edu [Department of Mechanical Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2015-09-28

    Empirical potential-based quasi-continuum theory (EQT) provides a route to incorporate atomistic detail into continuum framework such as the Nernst-Planck equation. EQT can also be used to construct a grand potential functional for classical density functional theory (cDFT). The combination of EQT and cDFT provides a simple and fast approach to predict the inhomogeneous density, potential profiles, and thermodynamic properties of confined fluids. We extend the EQT-cDFT approach to confined fluid mixtures and demonstrate it by simulating a mixture of methane and hydrogen inside slit-like channels of graphene. We show that the EQT-cDFT predictions for the structure of the confined fluid mixture compare well with the molecular dynamics simulation results. In addition, our results show that graphene slit nanopores exhibit a selective adsorption of methane over hydrogen.

  4. Fluid region segmentation in OCT images based on convolution neural network

    Science.gov (United States)

    Liu, Dong; Liu, Xiaoming; Fu, Tianyu; Yang, Zhou

    2017-07-01

    In the retinal image, characteristics of fluid have great significance for diagnosis in eye disease. In the clinical, the segmentation of fluid is usually conducted manually, but is time-consuming and the accuracy is highly depend on the expert's experience. In this paper, we proposed a segmentation method based on convolution neural network (CNN) for segmenting the fluid from fundus image. The B-scans of OCT are segmented into layers, and patches from specific region with annotation are used for training. After the data set being divided into training set and test set, network training is performed and a good segmentation result is obtained, which has a significant advantage over traditional methods such as threshold method.

  5. Dielectric properties of transformer paper impregnated by mineral oil based magnetic fluid

    International Nuclear Information System (INIS)

    Timko, M; Marton, K; Tomco, L; Kopcansky, P; Koneracka, M

    2010-01-01

    The influence of combined magnetic and electric field on permittivity of transformer paper used in power transformers was observed. Transformer paper was impregnated by pure transformer oil ITO 100 and magnetic fluids based on transformer oil ITO 100 with different concentrations of magnetite nanoparticles. The measurements were carried out with help of high precision capacitance bridge. The electric intensity between circular planar electrodes was in the region of weak electric field (E > 10 6 V/m). The increase of electric permittivity of transformer paper impregnated by magnetic fluid opposite pure transformer paper was observed. The experiments showed that permittivity of insulator system consisting of pure transformer paper and impregnated transformer paper naturally depends on number of paper layers. The magnetodielectric effect was found to be dependent on magnetite nanoparticles concentration in magnetic fluids.

  6. Phase-resolved fluid dynamic forces of a flapping foil energy harvester based on PIV measurements

    Science.gov (United States)

    Liburdy, James

    2017-11-01

    Two-dimensional particle image velocimetry measurements are performed in a wind tunnel to evaluate the spatial and temporal fluid dynamic forces acting on a flapping foil operating in the energy harvesting regime. Experiments are conducted at reduced frequencies (k = fc/U) of 0.05 - 0.2, pitching angle of, and heaving amplitude of A / c = 0.6. The phase-averaged pressure field is obtained by integrating the pressure Poisson equation. Fluid dynamic forces are then obtained through the integral momentum equation. Results are compared with a simple force model based on the concept of flow impulse. These results help to show the detailed force distributions, their transient nature and aide in understanding the impact of the fluid flow structures that contribute to the power production.

  7. Investigation of the touch sensitivity of ER fluid based tactile display

    Science.gov (United States)

    Liu, Yanju; Davidson, Rob; Taylor, Paul

    2005-05-01

    A tactile display is programmable device whose controlled surface is intended to be investigated by human touch. It has a great number of potential applications in the field of virtual reality and elsewhere. In this research, a 5x5 touch sensitive tactile display array including electrorheological (ER) fluid has been developed and investigated. Experimental results show that the sensed surface information could be controlled effectively by adjusting the voltage activation pattern imposed on the tactels. In the meantime, it is possible to sense the touching force normal to the display"s surface by monitoring the change of current passing through the ER fluid. These encouraging results are helpful for constructing a new type of tactile display based on ER fluid which can act as both sensor and actuator at the same time.

  8. Working Memory and Fluid Intelligence: Capacity, Attention Control, and Secondary Memory Retrieval

    Science.gov (United States)

    Unsworth, Nash; Fukuda, Keisuke; Awh, Edward; Vogel, Edward K.

    2015-01-01

    Several theories have been put forth to explain the relation between working memory (WM) and gF. Unfortunately, no single factor has been shown to fully account for the relation between these two important constructs. In the current study we tested whether multiple factors (capacity, attention control, and secondary memory) would collectively account for the relation. A large number of participants performed multiple measures of each construct and latent variable analyses were used to examine the data. The results demonstrated that capacity, attention control, and secondary memory were uniquely related to WM storage, WM processing, and gF. Importantly, the three factors completely accounted for the relation between WM (both processing and storage) and gF. Thus, although storage and processing make independent contributions to gF, both of these contributions are accounted for by variation in capacity, attention control and secondary memory. These results are consistent with the multifaceted view of WM, suggesting that individual differences in capacity, attention control, and secondary memory jointly account for individual differences in WM and its relation with gF. PMID:24531497

  9. Working memory and fluid intelligence: capacity, attention control, and secondary memory retrieval.

    Science.gov (United States)

    Unsworth, Nash; Fukuda, Keisuke; Awh, Edward; Vogel, Edward K

    2014-06-01

    Several theories have been put forth to explain the relation between working memory (WM) and gF. Unfortunately, no single factor has been shown to fully account for the relation between these two important constructs. In the current study we tested whether multiple factors (capacity, attention control, and secondary memory) would collectively account for the relation. A large number of participants performed multiple measures of each construct and latent variable analyses were used to examine the data. The results demonstrated that capacity, attention control, and secondary memory were uniquely related to WM storage, WM processing, and gF. Importantly, the three factors completely accounted for the relation between WM (both processing and storage) and gF. Thus, although storage and processing make independent contributions to gF, both of these contributions are accounted for by variation in capacity, attention control and secondary memory. These results are consistent with the multifaceted view of WM, suggesting that individual differences in capacity, attention control, and secondary memory jointly account for individual differences in WM and its relation with gF. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Performance analysis of an organic Rankine cycle with internal heat exchanger having zeotropic working fluid

    Directory of Open Access Journals (Sweden)

    Thoranis Deethayat

    2015-09-01

    Full Text Available In this study, performance of a 50 kW organic Rankine cycle (ORC with internal heat exchanger (IHE having R245fa/R152a zeotropic refrigerant with various compositions was investigated. The IHE could reduce heat rate at the ORC evaporator and better cycle efficiency could be obtained. The zeotropic mixture could reduce the irreversibilities during the heat exchanges at the ORC evaporator and the ORC condenser due to its gliding temperature; thus the cycle working temperatures came closer to the temperatures of the heat source and the heat sink. In this paper, effects of evaporating temperature, mass fraction of R152a and effectiveness of internal heat exchanger on the ORC performances for the first law and the second law of thermodynamics were considered. The simulated results showed that reduction of R245fa composition could reduce the irreversibilities at the evaporator and the condenser. The suitable composition of R245fa was around 80% mass fraction and below this the irreversibilities were nearly steady. Higher evaporating temperature and higher internal heat exchanger effectiveness also increased the first law and second law efficiencies. A set of correlations to estimate the first and the second law efficiencies with the mass fraction of R245fa, the internal heat exchanger effectiveness and the evaporating temperature were also developed.

  11. Well successfully drilled with high performance water-based fluid: Santos Basins, offshore Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Fornasier, Frank C.; Luzardo, Juan P. [Halliburton Company, Houston, TX (United States); Bishnoi, M.L. [Oil and Natural Gas Corporation Ltda. (ONGC), Dehradun (India)

    2012-07-01

    Santos Basin is a 352,260 square kilometers (136,010 sq mi) offshore pre-salt basin. It is located in the South Atlantic Ocean, some 300 kilometers (190 mi) South East of Sao Paulo, Brazil. One of the largest Brazilian sedimentary basins, it is the site of several recent significant oil fields, including Tupi and Jupiter. The criteria for drilling fluid selection is based upon the following factors: maximum cost efficiency, environmental friendliness, optimum borehole stability, and ease of use. The recommended drilling fluid formulation takes into consideration the experience gained during the drilling of wells in the Santos Basin area. The operator wanted to use a high-performance water-based fluid (HPWBF) that could provide shale inhibition, wellbore stability, lubricity and improved rate of penetration (ROP) as an alternative to synthetic-based drilling fluids to present value in terms of economics and environmental friendliness. The HPWBF consists of three synergistic products: a hydration suppressant, a dispersion suppressant, and an accretion suppressant. The system is formulated based on customized solutions for managing the clay reactivity. High logistics costs require drilling fluids that can be prepared with sea water and discharged to the sea without environmental impact. The HPWBF is a clay-free system designed for maximum shale inhibition in highly reactive formations. The system can provide wellbore stability, high rates of penetration, and acceptable rheological properties over a wide range of temperatures, with the added benefit of allowing cuttings discharge based upon water base environmental restrictions. Since no oil is used in the formulation, the HPWBF eliminates the need for cuttings processing and monitoring equipment, and exceeds the environmental requirements by achieving an LC50 value of 345,478.22 ppm in comparison with the minimum requirement (LC50 > 30,000 ppm in 96 hr), permitting use and discharge to the sea. The HPWBF selected

  12. Interim LCA comparison of metal working fluids with and without Chlorinated paraffins

    DEFF Research Database (Denmark)

    Olsen, Stig Irving; Christensen, Frans Møller

    2002-01-01

    tube with an outer diameter of 19.5 mm and material thickness of 1.65 mm (corresponding to approx. 1340 m tube). The tube is used as a heat-exchanger tube and the quality named 2205. The study has focused on European based operations since most known processes in the product system takes place...... raw materials to the producer of MWF. Transport from MWF supplier to the company is assumed to be identical for the two alternatives. All energy data has been taken from the LCAiT database, so e.g. electricity is European average from 1994. The MWFs used are produced in Sweden and data has been....... The results of the impact assessment show that there are only minor differences between the two alternative systems. The differences are due to a slightly larger use of energy and steel in the production of tubes when using the non-chlorinated alternative to MCCP based MWF, i.e. a slightly less environmental...

  13. Numerical analysis of an air condenser working with the refrigerant fluid R407C

    International Nuclear Information System (INIS)

    Aprea, Ciro; Maiorino, Angelo

    2007-01-01

    As CFC (clorofluorocarbon) and HCFC (hydrochlorofluorocarbon) refrigerants which have been used as refrigerants in a vapour compression refrigeration system were know to provide a principal cause to ozone depletion and global warming, production and use of these refrigerants have been restricted. Therefore, new alternative refrigerants should be searched for, which fit to the requirements in an air conditioner or a heat pump, and refrigerant mixtures which are composed of HFC (hydrofluorocarbon) refrigerants having zero ODP (ozone depletion potential) are now being suggested as drop-in or mid-term replacement. However also these refrigerants, as the CFC and HCFC refrigerants, present a greenhouse effect. The zeotropic mixture designated as R407C (R32/R125/R134a 23/25/52% in mass) represents a substitute of the HCFC22 for high evaporation temperature applications as the air-conditioning. Aim of the paper is a numerical-experimental analysis for an air condenser working with the non azeotropic mixture R407C in steady-state conditions. A homogeneous model for the condensing refrigerant is considered to forecast the performances of the condenser; this model is capable of predicting the distributions of the refrigerant temperature, the velocity, the void fraction, the tube wall temperature and the air temperature along the test condenser. Obviously in the refrigerant de-superheating phase the numerical analysis becomes very simple. A comparison with the measurements on an air condenser mounted in an air channel linked to a vapour compression plant is discussed. The results show that the simplified model provides a reasonable estimation of the steady-state response and that this model is useful to design purposes

  14. Beyond fluid intelligence and personality traits in social support: the role of ability based emotional intelligence.

    Science.gov (United States)

    Fabio, Annamaria Di

    2015-01-01

    Social support represents an important individual resource that has been associated with multiple indices of adaptive functioning and resiliency. Existing research has also identified an association between emotional intelligence (EI) and social support. The present study builds on prior research by investigating the contributions of ability based EI to social support, beyond the effects of fluid intelligence and personality traits. The Advanced Progressive Matrices, the Big Five Questionnaire, the Mayer Salovey Caruso EI test (MSCEIT), and the Multidimensional Scale of Perceived Social Support were administered to 149 Italian high school students. The results showed that ability based EI added significant incremental variance in explaining perceived social support, beyond the variance due to fluid intelligence and personality traits. The results underline the role of ability based EI in relation to perceived social support. Since ability based EI can be increased through specific training, the results of the present study highlight new possibilities for research and intervention in a preventive framework.

  15. Performance-Based Rewards and Work Stress

    Science.gov (United States)

    Ganster, Daniel C.; Kiersch, Christa E.; Marsh, Rachel E.; Bowen, Angela

    2011-01-01

    Even though reward systems play a central role in the management of organizations, their impact on stress and the well-being of workers is not well understood. We review the literature linking performance-based reward systems to various indicators of employee stress and well-being. Well-controlled experiments in field settings suggest that certain…

  16. Reliably measuring the condition of mineral-based transfer fluids using a permittivity sensor – practical application to thermal fluid heat transfer

    Directory of Open Access Journals (Sweden)

    Christopher Ian Wright

    2015-09-01

    Full Text Available This article describes a series of experiments to assess the performance and suitability of a permittivity sensor in the area of heat transfer. The permittivity sensor measures condition index and temperature of a fluid. A series of 5 experiments was conducted. They assessed the reproducibility of the sensor using both clean and dirty fluid samples, and showed the sensor had good reproducibility based on calculations of coefficients of variation. The sensor also detected water contamination, assessed from construction of a stimulus-response curve to step-wise increases in water and from real-life samples where water content was reported to be out of specification. Further experiments tested the association between condition index and both water content and fluid cleanliness in a real-life setting. Results demonstrated the sensor that condition index reflected changes in fluid water and cleanliness and was therefore a measure of fluid condition. The implication of these findings is that the sensor can be used to make rapid and reliable assessments of fluid condition using only small samples (i.e., <50 ml. The sensor may be of benefit to customers that need to make a lot of regular samples over a large processing site, such as concentrated solar power plants.

  17. Work, Train, Win: Work-Based Learning Design and Management for Productivity Gains. OECD Education Working Papers, No. 135

    Science.gov (United States)

    Kis, Viktoria

    2016-01-01

    Realising the potential of work-based learning schemes as a driver of productivity requires careful design and support. The length of work-based learning schemes should be adapted to the profile of productivity gains. A scheme that is too long for a given skill set might be unattractive for learners and waste public resources, but a scheme that is…

  18. Computational fluid dynamics simulation of a single cylinder research engine working with biodiesel

    Directory of Open Access Journals (Sweden)

    Moldovanu Dan

    2013-01-01

    Full Text Available The main objective of the paper is to present the results of the CFD simulation of a DI single cylinder engine using diesel, biodiesel, or different mixture proportions of diesel and biodiesel and compare the results to a test bed measurement in the same functioning point. The engine used for verifying the results of the simulation is a single cylinder research engine from AVL with an open ECU, so that the injection timings and quantities can be controlled and analyzed. In Romania, until the year 2020 all the fuel stations are obliged to have mixtures of at least 10% biodiesel in diesel [14]. The main advantages using mixtures of biofuels in diesel are: the fact that biodiesel is not harmful to the environment; in order to use biodiesel in your engine no modifications are required; the price of biodiesel is smaller than diesel and also if we compare biodiesel production to the classic petroleum based diesel production, it is more energy efficient; biodiesel assures more lubrication to the engine so the life of the engine is increased; biodiesel is a sustainable fuel; using biodiesel helps maintain the environment and it keeps the people more healthy [1-3].

  19. Helping fluid teams work: A research agenda for effective team adaptation in healthcare.

    Science.gov (United States)

    Bedwell, Wendy L; Ramsay, P Scott; Salas, Eduardo

    2012-12-01

    Although membership changes within teams are a common practice, research into this phenomenon is relatively nascent (Summers et al.; Acad Manag J 55:314-338, 2012). The small literature base, however, does provide insight into skills required for effective adaptation. The purpose of this effort is to provide a brief research synopsis, leading to research hypotheses about medical team training. By generalizing previous scientific findings regarding skills required for effective membership adaptation in different kinds of teams, we posit mechanisms whereby teamwork training might also support adaptation among medical teams (Burke et al.; Qual & Saf Health Care 13:i96-i104, 2004 and Salas et al.; Theor Issues Ergon Sci 8:381-394, 2007). We provide an overview of the membership change literature. Drawing upon literature from both within and outside of the medical domain, we suggest a framework and research propositions to aid in research efforts designed to determine the best content for helping to create adaptable medical teams through team training efforts. For effective adaptation, we suggest ad hoc teams should be trained on generalizable teamwork skills, to share just "enough" and the "right" information, to engage in shared leadership, and to shift from explicit to implicit coordination. Our overarching goal was to present what is known from the general research literature on successful team adaptation to membership changes, and to propose a research agenda to evaluate whether findings generalize to member changes in medical teams.

  20. Numerical Modeling and Investigation of Fluid-Driven Fracture Propagation in Reservoirs Based on a Modified Fluid-Mechanically Coupled Model in Two-Dimensional Particle Flow Code

    Directory of Open Access Journals (Sweden)

    Jian Zhou

    2016-09-01

    Full Text Available Hydraulic fracturing is a useful tool for enhancing rock mass permeability for shale gas development, enhanced geothermal systems, and geological carbon sequestration by the high-pressure injection of a fracturing fluid into tight reservoir rocks. Although significant advances have been made in hydraulic fracturing theory, experiments, and numerical modeling, when it comes to the complexity of geological conditions knowledge is still limited. Mechanisms of fluid injection-induced fracture initiation and propagation should be better understood to take full advantage of hydraulic fracturing. This paper presents the development and application of discrete particle modeling based on two-dimensional particle flow code (PFC2D. Firstly, it is shown that the modeled value of the breakdown pressure for the hydraulic fracturing process is approximately equal to analytically calculated values under varied in situ stress conditions. Furthermore, a series of simulations for hydraulic fracturing in competent rock was performed to examine the influence of the in situ stress ratio, fluid injection rate, and fluid viscosity on the borehole pressure history, the geometry of hydraulic fractures, and the pore-pressure field, respectively. It was found that the hydraulic fractures in an isotropic medium always propagate parallel to the orientation of the maximum principal stress. When a high fluid injection rate is used, higher breakdown pressure is needed for fracture propagation and complex geometries of fractures can develop. When a low viscosity fluid is used, fluid can more easily penetrate from the borehole into the surrounding rock, which causes a reduction of the effective stress and leads to a lower breakdown pressure. Moreover, the geometry of the fractures is not particularly sensitive to the fluid viscosity in the approximate isotropic model.

  1. Evidence of improved fluid management in patients receiving haemodialysis following a self-affirmation theory-based intervention: A randomised controlled trial.

    Science.gov (United States)

    Wileman, Vari; Chilcot, Joseph; Armitage, Christopher J; Farrington, Ken; Wellsted, David M; Norton, Sam; Davenport, Andrew; Franklin, Gail; Da Silva Gane, Maria; Horne, Robert; Almond, Mike

    2016-01-01

    Haemodialysis patients are at risk of serious health complications; yet, treatment non-adherence remains high. Warnings about health risks associated with non-adherence may trigger defensive reactions. We studied whether an intervention based on self-affirmation theory reduced resistance to health-risk information and improved fluid treatment adherence. In a cluster randomised controlled trial, 91 patients either self-affirmed or completed a matched control task before reading about the health-risks associated with inadequate fluid control. Patients' perceptions of the health-risk information, intention and self-efficacy to control fluid were assessed immediately after presentation of health-risk information. Interdialytic weight gain (IDWG), excess fluid removed during haemodialysis, is a clinical measure of fluid treatment adherence. IDWG data were collected up to 12 months post-intervention. Self-affirmed patients had significantly reduced IDWG levels over 12 months. However, contrary to predictions derived from self-affirmation theory, self-affirmed participants and controls did not differ in their evaluation of the health-risk information, intention to control fluid or self-efficacy. A low-cost, high-reach health intervention based on self-affirmation theory was shown to reduce IDWG over a 12-month period, but the mechanism by which this apparent behaviour change occurred is uncertain. Further work is still required to identify mediators of the observed effects.

  2. Work-Based Learning, Identity and Organisational Culture

    Science.gov (United States)

    Ahlgren, Linda; Tett, Lyn

    2010-01-01

    This paper discusses the ways in which employers view the contribution of work-based learning, how participating learners' experience the provision offered to them and how far work-based programmes can contribute to changing the discourse about learning from one of deficit to one of strengths. It draws on two complementary studies of work based…

  3. Work-Based Learning: A New Higher Education?

    Science.gov (United States)

    Boud, David, Ed.; Solomon, Nicky, Ed.

    This three-part book contains 16 chapters exploring work-based learning from a theoretical and case-study perspective in the United Kingdom. Part 1, Framing Work-based Learning, contains the following four chapters: "New Practices for New Times" (David Boud, Nicky Solomon, and Colin Symes); "Repositioning Universities and Work"…

  4. Structure of transformer oil-based magnetic fluids studied using acoustic spectroscopy

    International Nuclear Information System (INIS)

    Kúdelčík, Jozef; Bury, Peter; Drga, Jozef; Kopčanský, Peter; Závišová, Vlasta; Timko, Milan

    2013-01-01

    The structural changes in transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature were studied by acoustic spectroscopy. The attenuation of acoustic wave was measured as a function of the magnetic field in the range of 0–300 mT and in the temperature range of 15–35 °C for various magnetic nanoparticles concentrations. The effect of anisotropy of the acoustic attenuation was determined, too. The both strong influence of the magnetic field on the acoustic attenuation and its hysteresis were observed. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs, leading to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids also has very important influence on the structural changes because of the mechanism of thermal motion that acts against the cluster creation. The observed influences of both magnetic field and temperature on the investigated magnetic fluid structure are discussed. - Highlights: ► Structural changes in transformer oil-based magnetic fluids were investigated. ► The acoustic spectroscopy as the method of investigation was used. ► The influence of magnetic field on the structural was studied. ► The influence of temperatures on the structures was investigated, too. ► The influence of external conditions on the structure of MF is interpreted.

  5. Comparison of Theories of Anisotropy in Transformer Oil-Based Magnetic Fluids

    Directory of Open Access Journals (Sweden)

    Jozef Kudelcik

    2013-01-01

    Full Text Available The external magnetic field in transformer oil-based magnetic fluids leads to the aggregation of magnetic nanoparticles and formation of clusters. These aggregations are the result of the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs. However, the temperature of magnetic fluids has also very important influence on the structural changes because the mechanism of thermal motion acts against the cluster creation. The acoustic spectroscopy was used to study the anisotropy of transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature. In present the anisotropy of the magnetic fluids can be described by two theories. Taketomi theory assumes the existence of spherical clusters. These clusters form long chains, aligned in a magnetic field direction. Shliomis in his theory supposed that only nanoparticles formed chains. A comparison of the experimental results with the predictions of the Taketomi theory allowed a determination of the cluster radius and the number density of the colloidal particles. The proportions of the acoustic wave energy used for excitation of the translational and rotational motion were determined.

  6. Structure of transformer oil-based magnetic fluids studied using acoustic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kudelcik, Jozef, E-mail: kudelcik@fyzika.uniza.sk [Department of Physics, University of Zilina, Univerzitna 1, 010 01 Zilina (Slovakia); Bury, Peter; Drga, Jozef [Department of Physics, University of Zilina, Univerzitna 1, 010 01 Zilina (Slovakia); Kopcansky, Peter; Zavisova, Vlasta; Timko, Milan [Department of Magnetism, IEP SAS, Watsonova 47, 040 01 Kosice (Slovakia)

    2013-01-15

    The structural changes in transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature were studied by acoustic spectroscopy. The attenuation of acoustic wave was measured as a function of the magnetic field in the range of 0-300 mT and in the temperature range of 15-35 Degree-Sign C for various magnetic nanoparticles concentrations. The effect of anisotropy of the acoustic attenuation was determined, too. The both strong influence of the magnetic field on the acoustic attenuation and its hysteresis were observed. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs, leading to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids also has very important influence on the structural changes because of the mechanism of thermal motion that acts against the cluster creation. The observed influences of both magnetic field and temperature on the investigated magnetic fluid structure are discussed. - Highlights: Black-Right-Pointing-Pointer Structural changes in transformer oil-based magnetic fluids were investigated. Black-Right-Pointing-Pointer The acoustic spectroscopy as the method of investigation was used. Black-Right-Pointing-Pointer The influence of magnetic field on the structural was studied. Black-Right-Pointing-Pointer The influence of temperatures on the structures was investigated, too. Black-Right-Pointing-Pointer The influence of external conditions on the structure of MF is interpreted.

  7. Buffer fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mirzadzhanzade, A Kh; Dedusanko, G Ya; Dinaburg, L S; Markov, Yu M; Rasizade, Ya N; Rozov, V N; Sherstnev, N M

    1979-08-30

    A drilling fluid is suggested for separating the drilling and plugging fluids which contains as the base increased solution of polyacrylamide and additive. In order to increase the viscoelastic properties of the liquid with simultaneous decrease in the periods of its fabrication, the solution contains as an additive dry bentonite clay. In cases of the use of a buffer fluid under conditions of negative temperatures, it is necessary to add to it table salt or ethylene glycol.

  8. Phantom-based experimental validation of computational fluid dynamics simulations on cerebral aneurysms

    Energy Technology Data Exchange (ETDEWEB)

    Sun Qi; Groth, Alexandra; Bertram, Matthias; Waechter, Irina; Bruijns, Tom; Hermans, Roel; Aach, Til [Philips Research Europe, Weisshausstrasse 2, 52066 Aachen (Germany) and Institute of Imaging and Computer Vision, RWTH Aachen University, Sommerfeldstrasse 24, 52074 Aachen (Germany); Philips Research Europe, Weisshausstrasse 2, 52066 Aachen (Germany); Philips Healthcare, X-Ray Pre-Development, Veenpluis 4-6, 5684PC Best (Netherlands); Institute of Imaging and Computer Vision, RWTH Aachen University, Sommerfeldstrasse 24, 52074 Aachen (Germany)

    2010-09-15

    Purpose: Recently, image-based computational fluid dynamics (CFD) simulation has been applied to investigate the hemodynamics inside human cerebral aneurysms. The knowledge of the computed three-dimensional flow fields is used for clinical risk assessment and treatment decision making. However, the reliability of the application specific CFD results has not been thoroughly validated yet. Methods: In this work, by exploiting a phantom aneurysm model, the authors therefore aim to prove the reliability of the CFD results obtained from simulations with sufficiently accurate input boundary conditions. To confirm the correlation between the CFD results and the reality, virtual angiograms are generated by the simulation pipeline and are quantitatively compared to the experimentally acquired angiograms. In addition, a parametric study has been carried out to systematically investigate the influence of the input parameters associated with the current measuring techniques on the flow patterns. Results: Qualitative and quantitative evaluations demonstrate good agreement between the simulated and the real flow dynamics. Discrepancies of less than 15% are found for the relative root mean square errors of time intensity curve comparisons from each selected characteristic position. The investigated input parameters show different influences on the simulation results, indicating the desired accuracy in the measurements. Conclusions: This study provides a comprehensive validation method of CFD simulation for reproducing the real flow field in the cerebral aneurysm phantom under well controlled conditions. The reliability of the CFD is well confirmed. Through the parametric study, it is possible to assess the degree of validity of the associated CFD model based on the parameter values and their estimated accuracy range.

  9. Computational Fluid Dynamics Analysis Method Developed for Rocket-Based Combined Cycle Engine Inlet

    Science.gov (United States)

    1997-01-01

    Renewed interest in hypersonic propulsion systems has led to research programs investigating combined cycle engines that are designed to operate efficiently across the flight regime. The Rocket-Based Combined Cycle Engine is a propulsion system under development at the NASA Lewis Research Center. This engine integrates a high specific impulse, low thrust-to-weight, airbreathing engine with a low-impulse, high thrust-to-weight rocket. From takeoff to Mach 2.5, the engine operates as an air-augmented rocket. At Mach 2.5, the engine becomes a dual-mode ramjet; and beyond Mach 8, the rocket is turned back on. One Rocket-Based Combined Cycle Engine variation known as the "Strut-Jet" concept is being investigated jointly by NASA Lewis, the U.S. Air Force, Gencorp Aerojet, General Applied Science Labs (GASL), and Lockheed Martin Corporation. Work thus far has included wind tunnel experiments and computational fluid dynamics (CFD) investigations with the NPARC code. The CFD method was initiated by modeling the geometry of the Strut-Jet with the GRIDGEN structured grid generator. Grids representing a subscale inlet model and the full-scale demonstrator geometry were constructed. These grids modeled one-half of the symmetric inlet flow path, including the precompression plate, diverter, center duct, side duct, and combustor. After the grid generation, full Navier-Stokes flow simulations were conducted with the NPARC Navier-Stokes code. The Chien low-Reynolds-number k-e turbulence model was employed to simulate the high-speed turbulent flow. Finally, the CFD solutions were postprocessed with a Fortran code. This code provided wall static pressure distributions, pitot pressure distributions, mass flow rates, and internal drag. These results were compared with experimental data from a subscale inlet test for code validation; then they were used to help evaluate the demonstrator engine net thrust.

  10. Phantom-based experimental validation of computational fluid dynamics simulations on cerebral aneurysms

    International Nuclear Information System (INIS)

    Sun Qi; Groth, Alexandra; Bertram, Matthias; Waechter, Irina; Bruijns, Tom; Hermans, Roel; Aach, Til

    2010-01-01

    Purpose: Recently, image-based computational fluid dynamics (CFD) simulation has been applied to investigate the hemodynamics inside human cerebral aneurysms. The knowledge of the computed three-dimensional flow fields is used for clinical risk assessment and treatment decision making. However, the reliability of the application specific CFD results has not been thoroughly validated yet. Methods: In this work, by exploiting a phantom aneurysm model, the authors therefore aim to prove the reliability of the CFD results obtained from simulations with sufficiently accurate input boundary conditions. To confirm the correlation between the CFD results and the reality, virtual angiograms are generated by the simulation pipeline and are quantitatively compared to the experimentally acquired angiograms. In addition, a parametric study has been carried out to systematically investigate the influence of the input parameters associated with the current measuring techniques on the flow patterns. Results: Qualitative and quantitative evaluations demonstrate good agreement between the simulated and the real flow dynamics. Discrepancies of less than 15% are found for the relative root mean square errors of time intensity curve comparisons from each selected characteristic position. The investigated input parameters show different influences on the simulation results, indicating the desired accuracy in the measurements. Conclusions: This study provides a comprehensive validation method of CFD simulation for reproducing the real flow field in the cerebral aneurysm phantom under well controlled conditions. The reliability of the CFD is well confirmed. Through the parametric study, it is possible to assess the degree of validity of the associated CFD model based on the parameter values and their estimated accuracy range.

  11. Demands–abilities fit, work beliefs, meaningful work and engagement in nature-based jobs

    Directory of Open Access Journals (Sweden)

    Nellie de Crom

    2018-03-01

    Full Text Available Orientation: Meaningful work and personal engagement are important dimensions of flourishing of employees, especially when individuals work in challenging jobs. Research purpose: This study aimed to investigate the relationship between demands–abilities fit, work beliefs, meaningful work and engagement in individuals in nature-based jobs. Motivation for the study: Individuals working in nature often work under challenging circumstances without the necessary resources. A research gap exists regarding the effects of demands–abilities fit and work beliefs on meaningful work. It is also not clear how these antecedents and meaningful work will impact the engagement of individuals working in nature. Research approach, design and method: A cross-sectional survey was used with a convenience sample of 161 nature-based employees. Data were collected using a structured online questionnaire consisting of items from the demands–abilities fit scale, work–life questionnaire, work and meaning Inventory, work engagement scale and a biographical questionnaire. Main findings: Work beliefs (calling, career and job and demands–abilities fit predicted a large percentage of the variance in meaning making. Work beliefs (calling and job and demands–abilities fit also predicted a large percentage of the variance in greater good motivations. Demands–abilities fit and a calling work orientation indirectly affected work engagement via meaningful work. The scales which measured calling and job orientations showed insufficient discriminant validity in relation to the scales which measured positive meaning and work engagement. Practical and managerial implications: Managers should consider implementing interventions to affect the demands–abilities fit (through human resource management interventions and work beliefs of individuals working in nature (through job crafting. Promoting perceptions of meaningful work might contribute to higher personal engagement

  12. Influence of non-edible vegetable based oil as cutting fluid on chip, surface roughness and cutting force during drilling operation of Mild Steel

    Science.gov (United States)

    Susmitha, M.; Sharan, P.; Jyothi, P. N.

    2016-09-01

    Friction between work piece-cutting tool-chip generates heat in the machining zone. The heat generated reduces the tool life, increases surface roughness and decreases the dimensional sensitiveness of work material. This can be overcome by using cutting fluids during machining. They are used to provide lubrication and cooling effects between cutting tool and work piece and cutting tool and chip during machining operation. As a result, important benefits would be achieved such longer tool life, easy chip flow and higher machining quality in the machining processes. Non-edible vegetable oils have received considerable research attention in the last decades owing to their remarkable improved tribological characteristics and due to increasing attention to environmental issues, have driven the lubricant industry toward eco friendly products from renewable sources. In the present work, different non-edible vegetable oils are used as cutting fluid during drilling of Mild steel work piece. Non-edible vegetable oils, used are Karanja oil (Honge), Neem oil and blend of these two oils. The effect of these cutting fluids on chip formation, surface roughness and cutting force are investigated and the results obtained are compared with results obtained with petroleum based cutting fluids and dry conditions.

  13. Physics based simulation of seismicity induced in the vicinity of a high-pressure fluid injection

    Science.gov (United States)

    McCloskey, J.; NicBhloscaidh, M.; Murphy, S.; O'Brien, G. S.; Bean, C. J.

    2013-12-01

    High-pressure fluid injection into subsurface is known, in some cases, to induce earthquakes in the surrounding volume. The increasing importance of ';fracking' as a potential source of hydrocarbons has made the seismic hazard from this effect an important issue the adjudication of planning applications and it is likely that poor understanding of the process will be used as justification of refusal of planning in Ireland and the UK. Here we attempt to understand some of the physical controls on the size and frequency of induced earthquakes using a physics-based simulation of the process and examine resulting earthquake catalogues The driver for seismicity in our simulations is identical to that used in the paper by Murphy et al. in this session. Fluid injection is simulated using pore fluid movement throughout a permeable layer from a high-pressure point source using a lattice Boltzmann scheme. Diffusivities and frictional parameters can be defined independently at individual nodes/cells allowing us to reproduce 3-D geological structures. Active faults in the model follow a fractal size distribution and exhibit characteristic event size, resulting in a power-law frequency-size distribution. The fluid injection is not hydraulically connected to the fault (i.e. fluid does not come into physical contact with the fault); however stress perturbations from the injection drive the seismicity model. The duration and pressure-time function of the fluid injection can be adjusted to model any given injection scenario and the rate of induced seismicity is controlled by the local structures and ambient stress field as well as by the stress perturbations resulting from the fluid injection. Results from the rate and state fault models of Murphy et al. are incorporated to include the effect of fault strengthening in seismically quite areas. Initial results show similarities with observed induced seismic catalogues. Seismicity is only induced where the active faults have not been

  14. Scaling of Lift Degradation Due to Anti-Icing Fluids Based Upon the Aerodynamic Acceptance Test

    Science.gov (United States)

    Broeren, Andy P.; Riley, James T.

    2012-01-01

    In recent years, the FAA has worked with Transport Canada, National Research Council Canada (NRC) and APS Aviation, Inc. to develop allowance times for aircraft operations in ice-pellet precipitation. These allowance times are critical to ensure safety and efficient operation of commercial and cargo flights. Wind-tunnel testing with uncontaminated anti-icing fluids and fluids contaminated with simulated ice pellets had been carried out at the NRC Propulsion and Icing Wind Tunnel (PIWT) to better understand the flowoff characteristics and resulting aerodynamic effects. The percent lift loss on the thin, high-performance wing model tested in the PIWT was determined at 8 angle of attack and used as one of the evaluation criteria in determining the allowance times. Because it was unclear as to how performance degradations measured on this model were relevant to an actual airplane configuration, some means of interpreting the wing model lift loss was deemed necessary. This paper describes how the lift loss was related to the loss in maximum lift of a Boeing 737-200ADV airplane through the Aerodynamic Acceptance Test (AAT) performed for fluids qualification. A loss in maximum lift coefficient of 5.24 percent on the B737-200ADV airplane (which was adopted as the threshold in the AAT) corresponds to a lift loss of 7.3 percent on the PIWT model at 8 angle of attack. There is significant scatter in the data used to develop the correlation related to varying effects of the anti-icing fluids that were tested and other factors. A statistical analysis indicated the upper limit of lift loss on the PIWT model was 9.2 percent. Therefore, for cases resulting in PIWT model lift loss from 7.3 to 9.2 percent, extra scrutiny of the visual observations is required in evaluating fluid performance with contamination.

  15. Influence of the type of working fluid in the lower cycle and superheated steam parameters in the upper cycle on effectiveness of operation of binary power plant

    Directory of Open Access Journals (Sweden)

    Stachel Aleksander A.

    2015-03-01

    Full Text Available In the paper presented have been the results of the analysis of effectiveness of operation of binary power plant consisting of combined two Clausius-Rankine cycles, namely the binary cycle with water as a working fluid in the upper cycle and organic substance as a working fluid in the lower cycle, as well as a single fluid component power plant operating also in line with the C-R cycle for superheated steam, with water as a working fluid. The influence of the parameters of superheated steam in the upper cycle has been assessed as well as the type of working fluid in the lower cycle. The results of calculations have been referred to the single-cycle classical steam power plant operating at the same parameters of superheated steam and the same mass flow rate of water circulating in both cycles. On the basis of accomplished analysis it has been shown that the binary power plant shows a greater power with respect to the reference power plant.

  16. Effort-Based Career Opportunities and Working Time

    OpenAIRE

    Bratti, M.; Staffolani, S.

    2005-01-01

    The authors evaluate the economic effects of the hypothesis of effort-based career opportunities, described as a situation in which a firm creates incentives for employees to work longer hours than bargained (or desired), by making career prospects depend on relative working hours. Firms' personnel management policies may tend to increase working time (or workers' effort) in order to maximize profits. Effort-based career opportunities raise working time, production and output per worker, and ...

  17. Thermodynamic analysis of a thermal storage unit under the influence of nano-particles added to the phase change material and/or the working fluid

    Science.gov (United States)

    Abolghasemi, Mehran; Keshavarz, Ali; Mehrabian, Mozaffar Ali

    2012-11-01

    The thermal storage unit consists of two concentric cylinders where the working fluid flows through the internal cylinder and the annulus is filled with a phase change material. The system carries out a cyclic operation; each cycle consists of two processes. In the charging process the hot working fluid enters the internal cylinder and transfers heat to the phase change material. In the discharging process the cold working fluid enters the internal cylinder and absorbs heat from the phase change material. The differential equations governing the heat transfer between the two media are solved numerically. The numerical results are compared with the experimental results available in the literature. The performance of an energy storage unit is directly related to the thermal conductivity of nano-particles. The energy consumption of a residential unit whose energy is supplied by a thermal storage system can be reduced by 43 % when using nano-particles.

  18. Ubbelohde viscometer measurement of water-based Fe{sub 3}O{sub 4} magnetic fluid prepared by coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Gu, H. [School of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Tang, X. [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); Hong, R.Y., E-mail: rhong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002 (China); Feng, W.G. [Suzhou Nanocomp Inc., Suzhou New District, Suzhou 215011 (China); Xie, H.D.; Chen, D.X. [Suzhou YouNuo Plastic Industry Co., Ltd., Suzhou 215021 (China); Badami, D. [Department of Chemical Engineering, University of Waterloo, Waterloo, Canada ON N2L 3G1 (Canada)

    2013-12-15

    Fe{sub 3}O{sub 4} nanoparticles were prepared by co-precipitation and coated by sodium dodecyl benzene sulfonate (SDBS) to obtain water-based magnetic fluid. The viscosity of the magnetic fluid was measured using an Ubbelohde viscometer. The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity were studied. Experimental results showed that the magnetic fluid with low magnetic particle volume fraction behaved as a Newtonian fluid and the viscosity of the magnetic fluid increased with an increase of the suspended magnetic particles volume fraction. The experimental data was compared with the results of a theoretically derived equation. The viscosity of the magnetic fluid also increased with an increase in surfactant mass portion, while it decreased with increasing temperature. Moreover, the viscosity increased with increasing the magnetic field intensity. Increasing the temperature and the surfactant mass fraction weakened the influence of the magnetic field on the viscosity of the magnetic fluid. - Highlights: • Fe{sub 3}O{sub 4} nanoparticles were prepared using co-precipitation and coated by sodium dodecyl benzene sulfonate to obtain water-based magnetic fluid. • The viscosity of different magnetic fluids was measured using an Ubbelohde viscometer. • The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity of magnetic fluids were studied.

  19. Dynamic characteristics of Semi-active Hydraulic Engine Mount Based on Fluid-Structure Interaction FEA

    Directory of Open Access Journals (Sweden)

    Tian Jiande

    2015-01-01

    Full Text Available A kind of semi-active hydraulic engine mount is studied in this paper. After careful analysis of its structure and working principle, the FEA simulation of it was divided into two cases. One is the solenoid valve is open, so the air chamber connects to the atmosphere, and Fluid-Structure Interaction was used. Another is the solenoid valve is closed, and the air chamber has pressure, so Fluid-Structure-Gas Interaction was used. The test of this semi-active hydraulic engine mount was carried out to compare with the simulation results, and verify the accuracy of the model. Then the dynamic characteristics-dynamic stiffness and damping angle were analysed by simulation and test. This paper provides theoretical support for the development and optimization of the semi-active hydraulic engine mount.

  20. Performance optimization of low-temperature power generation by supercritical ORCs (organic Rankine cycles) using low GWP (global warming potential) working fluids

    International Nuclear Information System (INIS)

    Le, Van Long; Feidt, Michel; Kheiri, Abdelhamid; Pelloux-Prayer, Sandrine

    2014-01-01

    This paper presents the system efficiency optimization scenarios of basic and regenerative supercritical ORCs (organic Rankine cycles) using low-GWP (global warming potential) organic compounds as working fluid. A more common refrigerant, i.e. R134a, was also employed to make the comparison. A 150-°C, 5-bar-pressurized hot water is used to simulate the heat source medium. Power optimization was equally performed for the basic configuration of supercritical ORC. Thermodynamic performance comparison of supercritical ORCs using different working fluids was achieved by ranking method and exergy analysis method. The highest optimal efficiency of the system (η sys ) is always obtained with R152a in both basic (11.6%) and regenerative (13.1%) configurations. The highest value of optimum electrical power output (4.1 kW) is found with R1234ze. By using ranking method and considering low-GWP criterion, the best working fluids for system efficiency optimization of basic and regenerative cycles are R32 and R152a, respectively. The best working fluid for net electrical power optimization of basic cycle is R1234ze. Although CO 2 has many desirable environmental and safety properties (e.g. zero ODP (Ozone Depletion Potential), ultra low-GWP, non toxicity, non flammability, etc.), the worst thermodynamic performance is always found with the cycle using this compound as working fluid. - Highlights: • Performance optimizations were carried out for the supercritical ORCs using low-GWP working fluids. • Heat regeneration was used to improve the system efficiency of the supercritical ORC. • Thermodynamic performances of supercritical ORCs at the optima were evaluated by ranking method and exergy analysis

  1. A diffusion tensor imaging tractography algorithm based on Navier-Stokes fluid mechanics.

    Science.gov (United States)

    Hageman, Nathan S; Toga, Arthur W; Narr, Katherine L; Shattuck, David W

    2009-03-01

    We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color images of the DTI dataset.

  2. Yield shear stress model of magnetorheological fluids based on exponential distribution

    International Nuclear Information System (INIS)

    Guo, Chu-wen; Chen, Fei; Meng, Qing-rui; Dong, Zi-xin

    2014-01-01

    The magnetic chain model that considers the interaction between particles and the external magnetic field in a magnetorheological fluid has been widely accepted. Based on the chain model, a yield shear stress model of magnetorheological fluids was proposed by introducing the exponential distribution to describe the distribution of angles between the direction of magnetic field and the chain formed by magnetic particles. The main influencing factors were considered in the model, such as magnetic flux density, intensity of magnetic field, particle size, volume fraction of particles, the angle of magnetic chain, and so on. The effect of magnetic flux density on the yield shear stress was discussed. The yield stress of aqueous Fe 3 O 4 magnetreological fluids with volume fraction of 7.6% and 16.2% were measured by a device designed by ourselves. The results indicate that the proposed model can be used for calculation of yield shear stress with acceptable errors. - Highlights: • A yield shear stress model of magnetorheological fluids was proposed. • Use exponential distribution to describe the distribution of magnetic chain angles. • Experimental and predicted results were in good agreement for 2 types of MR

  3. Investigations of alteration zones based on fluid inclusion microthermometry at Sungun porphyry copper deposit, Iran

    Directory of Open Access Journals (Sweden)

    Omid ASGHARI

    2010-06-01

    Full Text Available The Sungun porphyry copper deposit is located in East Azerbaijan, NW of Iran. The porphyries occur as stocks and dikes ranging in composition from quartz monzodiorite to quartz monzonite. Four types of hypogene alteration are developed; potassic, phyllic, propylitic and argillic. Three types of fluid inclusions are typically observed at Sungun; (1 vapor-rich, (2 liquid-rich and (3 multi-phase. Halite is the principal solid phase in the latter. The primary multiphase inclusions within the quartz crystals were chosen for micro-thermometric analyses and considered to calculate the geological pressure and hydrothermal fluid density. In potassic zone, the average of homogenization temperature is 413.6 °C while in phyllic alteration, 375.9 °C. As expected in potassic alteration, the temperature of hydrothermal solutions is higher than that in the phyllic zone. The salinity of the hydrothermal fluids has a high coherency with homogenization temperature, so the average of salinity in potassic samples is 46.3 (wt% NaCl which is higher than phyllic samples. Based on the location of potassic alteration, as expected, the lithostatic pressure is much more than the phyllic one. Finally, the average density of hydrothermal fluids in the potassically altered samples is 1.124 (gr/cm3 which is higher than the ones in phyllic zone (1.083 gr/cm3 .

  4. New generation of membrane efficient water-based drilling fluids: pragmatic and cost-effective solutions to borehole stability problems

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U.A. [Haliburton, Calgary, AB (Canada); Mody, F.K. [Shell International E and P Inc., Calgary, AB (Canada); Tan, C.P. [CSIRO Petroleum, Kensington, WA (Australia)

    2002-06-01

    Drilling and completion operations in shales often suffer as a result of wellbore instability. Mechanical failure of the rock around a wellbore is the primary cause of shale instability. This process can be exacerbated by physico-chemical interactions between drilling fluids and shales. Water-based drilling fluids are used more and more due to environmental awareness that becomes more prevalent. Wellbore instability problems can however result from an improper application of water-based drilling fluids in those cases where drilling occurs in sensitive clay-rich formations. To meet the requirements of the petroleum industry, considerable collaborative efforts were expanded in the development of innovative environmentally acceptable water-based drilling fluids. In this paper, the authors describe the process that leads to the development of these drilling fluids. It is possible to achieve shale stability through an osmotic outflow of pore fluid and prevention/minimization of mud pressure penetration, as laboratory experiments on shale samples under realistic downhole conditions exposed to these drilling fluids prove. High membrane efficiencies, in excess of 80 per cent, were generated by this new generation of membrane efficient water-based drilling fluids. Drilling objectives resulting from an improved application of water-based drilling fluids are made possible by a fundamental understanding of the main drilling fluid-shale interaction mechanisms for shale stability and the application of experimental data to field conditions. The authors indicate that the achievement of trouble-free drilling of shales and notable reductions in non-productive time is accomplished by following the practical guidelines included in this paper for maintaining shale stability with the new generation of water-based drilling fluids. 8 refs., 2 tabs., 4 figs.

  5. Signal-based Gas Leakage Detection for Fluid Power Accumulators in Wind Turbines

    DEFF Research Database (Denmark)

    Liniger, Jesper; Sepehri, Nariman; N. Soltani, Mohsen

    2017-01-01

    This paper describes the development and application of a signal-based fault detection method for identifying gas leakage in hydraulic accumulators used in wind turbines. The method uses Multiresolution Signal Decomposition (MSD) based on wavelets for feature extraction from a~single fluid pressure...... measurement located close to the accumulator. Gas leakage is shown to create increased variations in this pressure signal. The Root Mean Square (RMS) of the detail coefficient Level 9 from the MSD is found as the most sensitive and robust fault indicator of gas leakage. The method is verified...... on an experimental setup allowing for the replication of the conditions for accumulators in wind turbines. Robustness is tested in a multi-fault environment where gas and external fluid leakage occurs simultaneously. In total, 24 experiments are performed, which show that the method is sensitive to gas leakage...

  6. Long Working Hours in Korea: Based on the 2014 Korean Working Conditions Survey

    OpenAIRE

    Park, Jungsun; Kim, Yangho; Han, Boyoung

    2017-01-01

    Background: Long working hours adversely affect worker safety and health. In 2004, Korea passed legislation that limited the work week to 40 hours, in an effort to improve quality-of-life and increase business competitiveness. This regulation was implemented in stages, first for large businesses and then for small businesses, from 2004 to 2011. We previously reported that average weekly working hours decreased from 2006 to 2010, based on the Korean Working Conditions Survey. Methods: In the p...

  7. Viscometric characterization of cobalt nanoparticle-based magnetorheological fluids using genetic algorithms

    International Nuclear Information System (INIS)

    Chaudhuri, Anirban; Wereley, Norman M.; Kotha, Sanjay; Radhakrishnan, Ramachandran; Sudarshan, Tirumalai S.

    2005-01-01

    The rheological flow curves (shear stress vs. shear rate) of a nanoparticle cobalt-based magnetorheological fluid can be modeled using Bingham-plastic and Herschel-Bulkley constitutive models. Steady-state rheological flow curves were measured using a parallel disk rheometer for constant shear rates as a function of applied magnetic field. Genetic algorithms were used to identify constitutive model parameters from the flow curve data

  8. Thermo-Economic and Heat Transfer Optimization of Working-Fluid Mixtures in a Low-Temperature Organic Rankine Cycle System

    Directory of Open Access Journals (Sweden)

    Oyeniyi A. Oyewunmi

    2016-06-01

    Full Text Available In the present paper, we consider the employment of working-fluid mixtures in organic Rankine cycle (ORC systems with respect to thermodynamic and heat-transfer performance, component sizing and capital costs. The selected working-fluid mixtures promise reduced exergy losses due to their non-isothermal phase-change behaviour, and thus improved cycle efficiencies and power outputs over their respective pure-fluid components. A multi-objective cost-power optimization of a specific low-temperature ORC system (operating with geothermal water at 98 °C reveals that the use of working-fluid-mixtures does indeed show a thermodynamic improvement over the pure-fluids. At the same time, heat transfer and cost analyses, however, suggest that it also requires larger evaporators, condensers and expanders; thus, the resulting ORC systems are also associated with higher costs. In particular, 50% n-pentane + 50% n-hexane and 60% R-245fa + 40% R-227ea mixtures lead to the thermodynamically optimal cycles, whereas pure n-pentane and pure R-245fa have lower plant costs, both estimated as having ∼14% lower costs per unit power output compared to the thermodynamically optimal mixtures. These conclusions highlight the importance of using system cost minimization as a design objective for ORC plants.

  9. Optimizing the multimodal approach to pancreatic cyst fluid diagnosis: developing a volume-based triage protocol.

    Science.gov (United States)

    Chai, Siaw Ming; Herba, Karl; Kumarasinghe, M Priyanthi; de Boer, W Bastiaan; Amanuel, Benhur; Grieu-Iacopetta, Fabienne; Lim, Ee Mun; Segarajasingam, Dev; Yusoff, Ian; Choo, Chris; Frost, Felicity

    2013-02-01

    The objective of this study was to develop a triage algorithm to optimize diagnostic yield from cytology, carcinoembryonic antigen (CEA), and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) testing on different components of a single pancreatic cyst fluid specimen. The authors also sought to determine whether cell block supernatant was suitable for CEA and KRAS testing. Fifty-four pancreatic cysts were triaged according to a volume-dependent protocol to generate fluid (neat and supernatant) and cell block specimens for cytology, comparative CEA, and KRAS testing. Follow-up histology, diagnostic cytology, or a combined clinicopathologic interpretation was recorded as the final diagnosis. There were 26 mucinous cystic lesions and 28 nonmucinous cystic lesions with volumes ranging from 0.3 mL to 55 mL. Testing different components of the specimens (cell block, neat, and/or supernatant) enabled all laboratory investigations to be performed on 50 of 54 cyst fluids (92.6%). Interpretive concordance was observed in 17 of 17 cases (100%) and in 35 of 40 cases (87.5%) that had multiple components tested for CEA and KRAS mutations, respectively. An elevated CEA level (>192 ng/mL) was the most sensitive test for the detection of a mucinous cystic lesion (62.5%) versus KRAS mutation (56%) and "positive" cytology (61.5%). KRAS mutations were identified in 2 of 25 mucinous cystic lesions (8%) in which cytology and CEA levels were not contributory. A volume-based protocol using different components of the specimen was able to optimize diagnostic yield in pancreatic cyst fluids. KRAS mutation testing increased diagnostic yield when combined with cytology and CEA analysis. The current results demonstrated that supernatant is comparable to neat fluid and cell block material for CEA and KRAS testing. Copyright © 2012 American Cancer Society.

  10. Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

    Science.gov (United States)

    Smith, Douglas D.; Hiller, John M.

    1998-01-01

    The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration.

  11. Modeling Mental Speed: Decomposing Response Time Distributions in Elementary Cognitive Tasks and Correlations with Working Memory Capacity and Fluid Intelligence

    Directory of Open Access Journals (Sweden)

    Florian Schmitz

    2016-10-01

    Full Text Available Previous research has shown an inverse relation between response times in elementary cognitive tasks and intelligence, but findings are inconsistent as to which is the most informative score. We conducted a study (N = 200 using a battery of elementary cognitive tasks, working memory capacity (WMC paradigms, and a test of fluid intelligence (gf. Frequently used candidate scores and model parameters derived from the response time (RT distribution were tested. Results confirmed a clear correlation of mean RT with WMC and to a lesser degree with gf. Highly comparable correlations were obtained for alternative location measures with or without extreme value treatment. Moderate correlations were found as well for scores of RT variability, but they were not as strong as for mean RT. Additionally, there was a trend towards higher correlations for slow RT bands, as compared to faster RT bands. Clearer evidence was obtained in an ex-Gaussian decomposition of the response times: the exponential component was selectively related to WMC and gf in easy tasks, while mean response time was additionally predictive in the most complex tasks. The diffusion model parsimoniously accounted for these effects in terms of individual differences in drift rate. Finally, correlations of model parameters as trait-like dispositions were investigated across different tasks, by correlating parameters of the diffusion and the ex-Gaussian model with conventional RT and accuracy scores.

  12. Performance and energy saving analysis of a refrigerator using hydrocarbon mixture (HC-R134a) as working fluid

    Science.gov (United States)

    Mohtar, M. N.; Nasution, H.; Aziz, A. A.

    2015-12-01

    The use of hydrocarbon mixture as a working fluid in a refrigerator system is rarely explored. Almost all domestic refrigerators use hydroflourocarbon R134a (HFC-R134a) as refrigerants. In this study, hydrocarbon gas (HC-R134a) is used as the alternative refrigerant to replace HFC-R134a. It has a composition of R290 (56%), R600a (54.39%) and additive (0.1%wt) blended for the trials. The experiments were conducted with 105 g and 52.5 g refrigerant mass charge, subjected to internal heat load of 0, 1, 2, 3 and 4 kg respectively. The study investigates the coefficient of performance of the refrigerator (COPR) and energy consumption. The results show that the use of HC-R134a as the replaceable refrigerant can save energy ranging from 2.04% to 7.09%, as compared to the conventional HFC-R134a refrigerant. Naturally, the COPR improvement and temperature distribution using HC-R134a are much better than HFC-R134a

  13. Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

    Science.gov (United States)

    Smith, D.D.; Hiller, J.M.

    1998-02-24

    The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.

  14. Working memory capacity and fluid intelligence are strongly related constructs: comment on Ackerman, Beier, and Boyle (2005).

    Science.gov (United States)

    Kane, Michael J; Hambrick, David Z; Conway, Andrew R A

    2005-01-01

    The authors agree with P. L. Ackerman, M. E. Beier, and M. O. Boyle (2005; see record 2004-22408-002) that working memory capacity (WMC) is not isomorphic with general fluid intelligence (Gf) or reasoning ability. However, the WMC and Gf/reasoning constructs are more strongly associated than Ackerman et al. (2005) indicate, particularly when considering the outcomes of latent-variable studies. The authors' reanalysis of 14 such data sets from 10 published studies, representing more than 3,100 young-adult subjects, suggests a strong correlation between WMC and Gf/reasoning factors (median r=.72), indicating that the WMC and Gf constructs share approximately 50% of their variance. This comment also clarifies the authors' "executive attention" view of WMC, it demonstrates that WMC has greater discriminant validity than Ackerman et al. (2005) implied, and it suggests some future directions and challenges for the scientific study of the convergence of WMC, attention control, and intelligence. Copyright (c) 2005 APA, all rights reserved.

  15. Competency-Based Education and the World of Work.

    Science.gov (United States)

    Huff, Sheila M.

    Some issues in connection with competency-based education (CBE) and the world of work discussed by the author include the relevance of CBE programs to work, the changing attitudes of students and young workers toward work, "credentialism" or the continual upgrading of educational requirements for employment, underemployment and CBE, and others.…

  16. Evaluation of the thermal performance of a solar water heating thermosyphon versus a two-phase closed thermosyphon using different working fluids

    Energy Technology Data Exchange (ETDEWEB)

    Ordaz-Flores, A. [Posgrado en Ingenieria (Energia), Univ. Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Garcia-Valladares, O.; Gomez, V.H. [Centro de Investigacion en Energia, Univ. Nacional Autonoma de Mexico, Temixco, Morelos (Mexico)

    2008-07-01

    A water heating closed two-phase thermosyphon solar system was designed and built. The system consists of a flat plate solar collector coupled to a thermotank by a continuous copper tubing in which the working fluid circulates. The working fluid evaporates in the collector and condensates in the thermotank transferring its latent heat to the water through a coil heat exchanger. The tested fluids are acetone and R134a. The thermal performance of the proposed systems is compared with a conventional solar water thermosyphon under the same operating conditions. Advantages of a two-phase system include the elimination of freezing, fouling, scaling and corrosion. Geometry and construction materials are the same except for the closed circuit presented in the two-phase system. Data were collected from temperature and pressure sensors throughout the two systems. Early results suggest that R134a may provide a better performance than acetone for this kind of systems. (orig.)

  17. Microfluidic-based Broadband Measurements of Fluid Permittivity and Permeability to 100 GHz

    Science.gov (United States)

    Little, Charles A. E.

    This dissertation concerns the development of unique microfluidic microwave devices and associated microwave calibrations to quantitatively extract the broadband permittivity and permeability of fluids between 100 kHz and 110 GHz. The devices presented here consist of SU-8- and PDMS-based microfluidic channels integrated lithographically with coplanar waveguides (CPWs), measured via an external vector network analyzer (VNA). By applying our hybrid set of microwave calibrations to the raw data we extract distributed circuit parameters, representative of the electromagnetic response of the microfluidic channel. We then correlate these parameters to the permittivity and permeability of the fluid within the channels. We are primarily focused on developing devices, calibrations, and analyses to characterize various chemical and biological systems. The small fluid volumes and overall scale of our devices lends the technique to point-of-care blood and cell analysis, as well as to the analysis of high-value chemicals. Broadband microwave microfluidics is sensitive to three primary categories of phenomena: Ionic, dipolar, and magnetic resonances. All three can occur in complex fluids such as blood, proteins and particle suspensions. In order to make quantitative measurements, we need to be able to model and separate all three types of responses. Here we first measure saline solutions (NaCl and water) as an ideal system to better understanding both the ionic and dipolar response. Specifically, we are targeting the electrical double-layer (EDL) response, an ionic effect, which dominates over the intrinsic fluid response at lower frequencies. We have found that the EDL response for saline obeys a strict Debye-type relaxation model, the frequency response of which is dependent solely on the conductivity of the solution. To develop a better understanding of the magnetic response, we first measure magnetic nanoparticles; showing it is possible to detect the magnetic resonances of

  18. Laboratory testing of extravascular body fluids in Croatia: a survey of the Working group for extravascular body fluids of the Croatian Society of Medical Biochemistry and Laboratory Medicine.

    Science.gov (United States)

    Kopcinovic, Lara Milevoj; Vogrinc, Zeljka; Kocijan, Irena; Culej, Jelena; Aralica, Merica; Jokic, Anja; Antoncic, Dragana; Bozovic, Marija

    2016-10-15

    We hypothesized that extravascular body fluid (EBF) analysis in Croatia is not harmonized and aimed to investigate preanalytical, analytical and postanalytical procedures used in EBF analysis in order to identify key aspects that should be addressed in future harmonization attempts. An anonymous online survey created to explore laboratory testing of EBF was sent to secondary, tertiary and private health care Medical Biochemistry Laboratories (MBLs) in Croatia. Statements were designed to address preanalytical, analytical and postanalytical procedures of cerebrospinal, pleural, peritoneal (ascites), pericardial, seminal, synovial, amniotic fluid and sweat. Participants were asked to declare the strength of agreement with proposed statements using a Likert scale. Mean scores for corresponding separate statements divided according to health care setting were calculated and compared. The survey response rate was 0.64 (58 / 90). None of the participating private MBLs declared to analyse EBF. We report a mean score of 3.45 obtained for all statements evaluated. Deviations from desirable procedures were demonstrated in all EBF testing phases. Minor differences in procedures used for EBF analysis comparing secondary and tertiary health care MBLs were found. The lowest scores were obtained for statements regarding quality control procedures in EBF analysis, participation in proficiency testing programmes and provision of interpretative comments on EBF's test reports. Although good laboratory EBF practice is present in Croatia, procedures for EBF analysis should be further harmonized to improve the quality of EBF testing and patient safety.

  19. Night work, long work weeks, and risk of accidental injuries. A register-based study

    DEFF Research Database (Denmark)

    Larsen, Ann D; Hannerz, Harald; Møller, Simone V

    2017-01-01

    of the European Labour Force Survey from 1999-2013. The current study was based on 150 438 participants (53% men and 47% women). Data on accidental injuries were obtained at individual level from national health registers. We included all 20-59-year-old employees working ≥32 hours a week at the time...... of the interview. We used Poisson regression to estimate the relative rates (RR) of accidental injuries as a function of night work or long work weeks (>40 hours per week) adjusted for year of interview, sex, age, socioeconomic status (SES), industry, and weekly working hours or night work. Age, sex and SES were....... No associations were found between long work weeks (>40 hours) and accidental injuries. Conclusion: We found a modest increased risk of accidental injuries when reporting night work. No associations between long work weeks and risk of accidental injuries were observed. Age, sex and SES showed no trends when...

  20. Magnetic field sensor based on cascaded microfiber coupler with magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Lianmin; Su, Delong; Wang, Zhaofang [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Pu, Shengli, E-mail: shlpu@usst.edu.cn [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zeng, Xianglong [The Key Lab of Specialty Fiber Optics and Optical Access Network, Shanghai University, Shanghai 200072 (China); Lahoubi, Mahieddine [Laboratory L.P.S., Department of Physics, Faculty of Sciences, Badji-Mokhtar Annaba University, Annaba 23000 (Algeria)

    2016-09-07

    A kind of magnetic field sensor based on cascaded microfiber coupler with magnetic fluid is proposed and experimentally demonstrated. The magnetic fluid is utilized as the cladding of the fused regions of the cascaded microfiber coupler. As the interference valley wavelength of the sensing structure is sensitive to the ambient variation, considering the magnetic-field-dependent refractive index of magnetic fluid, the proposed structure is employed for magnetic field sensing. The effective coupling length for each coupling region of the as-fabricated cascaded microfiber coupler is 6031 μm. The achieved sensitivity is 125 pm/Oe, which is about three times larger than that of the previously similar structure based on the single microfiber coupler. Experimental results indicate that the sensing sensitivity can be easily improved by increasing the effective coupling length or cascading more microfiber couplers. The proposed magnetic field sensor is attractive due to its low cost, immunity to electromagnetic interference, as well as high sensitivity, which also has the potentials in other tunable all-fiber photonic devices, such as filter.

  1. Methods for simulation-based analysis of fluid-structure interaction.

    Energy Technology Data Exchange (ETDEWEB)

    Barone, Matthew Franklin; Payne, Jeffrey L.

    2005-10-01

    Methods for analysis of fluid-structure interaction using high fidelity simulations are critically reviewed. First, a literature review of modern numerical techniques for simulation of aeroelastic phenomena is presented. The review focuses on methods contained within the arbitrary Lagrangian-Eulerian (ALE) framework for coupling computational fluid dynamics codes to computational structural mechanics codes. The review treats mesh movement algorithms, the role of the geometric conservation law, time advancement schemes, wetted surface interface strategies, and some representative applications. The complexity and computational expense of coupled Navier-Stokes/structural dynamics simulations points to the need for reduced order modeling to facilitate parametric analysis. The proper orthogonal decomposition (POD)/Galerkin projection approach for building a reduced order model (ROM) is presented, along with ideas for extension of the methodology to allow construction of ROMs based on data generated from ALE simulations.

  2. Simulations of fluid flow through porous media based on cellular automata and non-linear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Paulson, K V

    1992-05-15

    A study is being carried out to apply cellular automata and non-linear dynamics in the construction of efficient and accurate computer simulations of multiphase fluid flow through porous media, with the objective of application to reservoir modelling for hydrocarbon recovery. An algorithm based on Boolean operations has been developed which transforms a PC clone into a highly efficient vector processor capable of cellular automata simulation of single fluid flow through two-dimensional rock matrix models of varying porosities. Macroscopic flow patterns have been established through spatial and temporal averaging with no floating point operations. Permeabilities of the different models have been calculated. Hardware allows the algorithm to function on dual processors on a PC platform using a video recording and editing facility. Very encouraging results have been obtained. 4 figs.

  3. Fast Virtual Fractional Flow Reserve Based Upon Steady-State Computational Fluid Dynamics Analysis

    Directory of Open Access Journals (Sweden)

    Paul D. Morris, PhD

    2017-08-01

    Full Text Available Fractional flow reserve (FFR-guided percutaneous intervention is superior to standard assessment but remains underused. The authors have developed a novel “pseudotransient” analysis protocol for computing virtual fractional flow reserve (vFFR based upon angiographic images and steady-state computational fluid dynamics. This protocol generates vFFR results in 189 s (cf >24 h for transient analysis using a desktop PC, with <1% error relative to that of full-transient computational fluid dynamics analysis. Sensitivity analysis demonstrated that physiological lesion significance was influenced less by coronary or lesion anatomy (33% and more by microvascular physiology (59%. If coronary microvascular resistance can be estimated, vFFR can be accurately computed in less time than it takes to make invasive measurements.

  4. Image-based computational fluid dynamics in the lung: virtual reality or new clinical practice?

    Science.gov (United States)

    Burrowes, Kelly S; De Backer, Jan; Kumar, Haribalan

    2017-11-01

    The development and implementation of personalized medicine is paramount to improving the efficiency and efficacy of patient care. In the respiratory system, function is largely dictated by the choreographed movement of air and blood to the gas exchange surface. The passage of air begins in the upper airways, either via the mouth or nose, and terminates at the alveolar interface, while blood flows from the heart to the alveoli and back again. Computational fluid dynamics (CFD) is a well-established tool for predicting fluid flows and pressure distributions within complex systems. Traditionally CFD has been used to aid in the effective or improved design of a system or device; however, it has become increasingly exploited in biological and medical-based applications further broadening the scope of this computational technique. In this review, we discuss the advancement in application of CFD to the respiratory system and the contributions CFD is currently making toward improving precision medicine. The key areas CFD has been applied to in the pulmonary system are in predicting fluid transport and aerosol distribution within the airways. Here we focus our discussion on fluid flows and in particular on image-based clinically focused CFD in the ventilatory system. We discuss studies spanning from the paranasal sinuses through the conducting airways down to the level of the alveolar airways. The combination of imaging and CFD is enabling improved device design in aerosol transport, improved biomarkers of lung function in clinical trials, and improved predictions and assessment of surgical interventions in the nasal sinuses. WIREs Syst Biol Med 2017, 9:e1392. doi: 10.1002/wsbm.1392 For further resources related to this article, please visit the WIREs website. © 2017 Wiley Periodicals, Inc.

  5. Sampling guidelines for oral fluid-based surveys of group-housed animals.

    Science.gov (United States)

    Rotolo, Marisa L; Sun, Yaxuan; Wang, Chong; Giménez-Lirola, Luis; Baum, David H; Gauger, Phillip C; Harmon, Karen M; Hoogland, Marlin; Main, Rodger; Zimmerman, Jeffrey J

    2017-09-01

    Formulas and software for calculating sample size for surveys based on individual animal samples are readily available. However, sample size formulas are not available for oral fluids and other aggregate samples that are increasingly used in production settings. Therefore, the objective of this study was to develop sampling guidelines for oral fluid-based porcine reproductive and respiratory syndrome virus (PRRSV) surveys in commercial swine farms. Oral fluid samples were collected in 9 weekly samplings from all pens in 3 barns on one production site beginning shortly after placement of weaned pigs. Samples (n=972) were tested by real-time reverse-transcription PCR (RT-rtPCR) and the binary results analyzed using a piecewise exponential survival model for interval-censored, time-to-event data with misclassification. Thereafter, simulation studies were used to study the barn-level probability of PRRSV detection as a function of sample size, sample allocation (simple random sampling vs fixed spatial sampling), assay diagnostic sensitivity and specificity, and pen-level prevalence. These studies provided estimates of the probability of detection by sample size and within-barn prevalence. Detection using fixed spatial sampling was as good as, or better than, simple random sampling. Sampling multiple barns on a site increased the probability of detection with the number of barns sampled. These results are relevant to PRRSV control or elimination projects at the herd, regional, or national levels, but the results are also broadly applicable to contagious pathogens of swine for which oral fluid tests of equivalent performance are available. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Long Working Hours in Korea: Based on the 2014 Korean Working Conditions Survey

    Directory of Open Access Journals (Sweden)

    Jungsun Park

    2017-12-01

    Full Text Available Background: Long working hours adversely affect worker safety and health. In 2004, Korea passed legislation that limited the work week to 40 hours, in an effort to improve quality-of-life and increase business competitiveness. This regulation was implemented in stages, first for large businesses and then for small businesses, from 2004 to 2011. We previously reported that average weekly working hours decreased from 2006 to 2010, based on the Korean Working Conditions Survey. Methods: In the present study, we examine whether average weekly working hours continued to decrease in 2014 based on the 2014 Korean Working Conditions Survey. Results: The results show that average weekly working hours among all groups of workers decreased in 2014 relative to previous years; however, self-employed individuals and employers (who are not covered by the new legislation in the specific service sectors worked > 60 h/wk in 2014. Conclusion: The Korean government should prohibit employees from working excessive hours and should also attempt to achieve social and public consensus regarding work time reduction to improve the safety, health, and quality-of-life of all citizens, including those who are employers and self-employed. Keywords: employee, employer, Korea, self-employed, working hours

  7. Towards needs-based work environments : Psychological needs affecting the use and appreciation of activity-based work environments

    NARCIS (Netherlands)

    Jan Gerard Hoendervanger

    2015-01-01

    Activity-Based Working (ABW) is supported by work environments that combine hot-desking with a variety of workplaces, designed to support different types of activities. While the advantages of these work environments in terms of efficiency are undisputed, their effectiveness with respect to job

  8. Towards needs-based work environments: psychological needs affecting the use and appreciation of activity-based work environments

    NARCIS (Netherlands)

    Hoendervanger, Jan Gerard

    2015-01-01

    Activity-Based Working (ABW) is supported by work environments that combine hot-desking with a variety of workplaces, designed to support different types of activities. While the advantages of these work environments in terms of efficiency are undisputed, their effectiveness with respect to job

  9. Long Working Hours in Korea: Based on the 2014 Korean Working Conditions Survey.

    Science.gov (United States)

    Park, Jungsun; Kim, Yangho; Han, Boyoung

    2017-12-01

    Long working hours adversely affect worker safety and health. In 2004, Korea passed legislation that limited the work week to 40 hours, in an effort to improve quality-of-life and increase business competitiveness. This regulation was implemented in stages, first for large businesses and then for small businesses, from 2004 to 2011. We previously reported that average weekly working hours decreased from 2006 to 2010, based on the Korean Working Conditions Survey. In the present study, we examine whether average weekly working hours continued to decrease in 2014 based on the 2014 Korean Working Conditions Survey. The results show that average weekly working hours among all groups of workers decreased in 2014 relative to previous years; however, self-employed individuals and employers (who are not covered by the new legislation) in the specific service sectors worked > 60 h/wk in 2014. The Korean government should prohibit employees from working excessive hours and should also attempt to achieve social and public consensus regarding work time reduction to improve the safety, health, and quality-of-life of all citizens, including those who are employers and self-employed.

  10. Individual differences in working memory, secondary memory, and fluid intelligence: evidence from the levels-of-processing span task.

    Science.gov (United States)

    Rose, Nathan S

    2013-12-01

    Individual differences in working memory (WM) are related to performance on secondary memory (SM), and fluid intelligence (gF) tests. However, the source of the relation remains unclear, in part because few studies have controlled for the nature of encoding; therefore, it is unclear whether individual variation is due to encoding, maintenance, or retrieval processes. In the current study, participants performed a WM task (the levels-of-processing span task; Rose, Myerson, Roediger III, & Hale, 2010) and a SM test that tested for both targets and the distracting processing words from the initial WM task. Deeper levels of processing at encoding did not benefit WM, but did benefit subsequent SM, although the amount of benefit was smaller for those with lower WM spans. This result suggests that, despite encoding cues that facilitate retrieval from SM, low spans may have engaged in shallower, maintenance-focused processing to maintain the words in WM. Low spans also recalled fewer targets, more distractors, and more extralist intrusions than high spans, although this was partially due to low spans' poorer recall of targets, which resulted in a greater number of opportunities to commit recall errors. Delayed recall of intrusions and commission of source errors (labeling targets as processing words and vice versa) were significant negative predictors of gF. These results suggest that the ability to use source information to recall relevant information and withhold recall of irrelevant information is a critical source of both individual variation in WM and the relation between WM, SM, and gF. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

  11. Design and dynamic modeling of electrorheological fluid-based variable-stiffness fin for robotic fish

    Science.gov (United States)

    Bazaz Behbahani, Sanaz; Tan, Xiaobo

    2017-08-01

    Fish actively control their stiffness in different swimming conditions. Inspired by such an adaptive behavior, in this paper we study the design, prototyping, and dynamic modeling of compact, tunable-stiffness fins for robotic fish, where electrorheological (ER) fluid serves as the enabling element. A multi-layer composite fin with an ER fluid core is prototyped and utilized to investigate the influence of electrical field on its performance. Hamilton's principle is used to derive the dynamic equations of motion of the flexible fin, and Lighthill's large-amplitude elongated-body theory is adopted to estimate the hydrodynamic force when the fin undergoes base-actuated rotation. The dynamic equations are then discretized using the finite element method, to obtain an approximate numerical solution. Experiments are conducted on the prototyped flexible ER fluid-filled beam for parameter identification and validation of the proposed model, and for examining the effectiveness of electrically controlled stiffness tuning. In particular, it is found that the natural frequency is increased by almost 40% when the applied electric field changes from 0 to 1.5× {10}6 {{V}} {{{m}}}-1.

  12. Correlating contact line capillarity and dynamic contact angle hysteresis in surfactant-nanoparticle based complex fluids

    Science.gov (United States)

    Harikrishnan, A. R.; Dhar, Purbarun; Agnihotri, Prabhat K.; Gedupudi, Sateesh; Das, Sarit K.

    2018-04-01

    Dynamic wettability and contact angle hysteresis can be correlated to shed insight onto any solid-liquid interaction. Complex fluids are capable of altering the expected hysteresis and dynamic wetting behavior due to interfacial interactions. We report the effect of capillary number on the dynamic advancing and receding contact angles of surfactant-based nanocolloidal solutions on hydrophilic, near hydrophobic, and superhydrophobic surfaces by performing forced wetting and de-wetting experiments by employing the embedded needle method. A segregated study is performed to infer the contributing effects of the constituents and effects of particle morphology. The static contact angle hysteresis is found to be a function of particle and surfactant concentrations and greatly depends on the nature of the morphology of the particles. An order of estimate of line energy and a dynamic flow parameter called spreading factor and the transient variations of these parameters are explored which sheds light on the dynamics of contact line movement and response to perturbation of three-phase contact. The Cox-Voinov-Tanner law was found to hold for hydrophilic and a weak dependency on superhydrophobic surfaces with capillary number, and even for the complex fluids, with a varying degree of dependency for different fluids.

  13. Modern fluid dynamics

    CERN Document Server

    Kleinstreuer, Clement

    2018-01-01

    Modern Fluid Dynamics, Second Edition provides up-to-date coverage of intermediate and advanced fluids topics. The text emphasizes fundamentals and applications, supported by worked examples and case studies. Scale analysis, non-Newtonian fluid flow, surface coating, convection heat transfer, lubrication, fluid-particle dynamics, microfluidics, entropy generation, and fluid-structure interactions are among the topics covered. Part A presents fluids principles, and prepares readers for the applications of fluid dynamics covered in Part B, which includes computer simulations and project writing. A review of the engineering math needed for fluid dynamics is included in an appendix.

  14. Novel cavitation fluid jet polishing process based on negative pressure effects.

    Science.gov (United States)

    Chen, Fengjun; Wang, Hui; Tang, Yu; Yin, Shaohui; Huang, Shuai; Zhang, Guanghua

    2018-04-01

    Traditional abrasive fluid jet polishing (FJP) is limited by its high-pressure equipment, unstable material removal rate, and applicability to ultra-smooth surfaces because of the evident air turbulence, fluid expansion, and a large polishing spot in high-pressure FJP. This paper presents a novel cavitation fluid jet polishing (CFJP) method and process based on FJP technology. It can implement high-efficiency polishing on small-scale surfaces in a low-pressure environment. CFJP uses the purposely designed polishing equipment with a sealed chamber, which can generate a cavitation effect in negative pressure environment. Moreover, the collapse of cavitation bubbles can spray out a high-energy microjet and shock wave to enhance the material removal. Its feasibility is verified through researching the flow behavior and the cavitation results of the negative pressure cavitation machining of pure water in reversing suction flow. The mechanism is analyzed through a computational fluid dynamics simulation. Thus, its cavitation and surface removal mechanisms in the vertical CFJP and inclined CFJP are studied. A series of polishing experiments on different materials and polishing parameters are conducted to validate its polishing performance compared with FJP. The maximum removal depth increases, and surface roughness gradually decreases with increasing negative outlet pressures. The surface becomes smooth with the increase of polishing time. The experimental results confirm that the CFJP process can realize a high material removal rate and smooth surface with low energy consumption in the low-pressure environment, together with compatible surface roughness to FJP. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Hydrodynamic bearing lubricated with magnetic fluids

    International Nuclear Information System (INIS)

    Urreta, H; Leicht, Z; Sanchez, A; Agirre, A; Kuzhir, P; Magnac, G

    2009-01-01

    This paper summarizes the work carried out in the development of hydrodynamic lubricated journal bearings with magnetic fluids. Two different fluids have been analyzed, one ferrofluid from FERROTEC APG s10n and one magnetorheological fluid from LORD Corp., MRF122-2ED. Theoretical analysis has been carried out with numerical solutions of Reynolds equation, based on apparent viscosity modulation for ferrofluid and Bingham model for MR fluid. To validate this model, one test bench has been designed, manufactured and set up, where preliminary results shown in this paper demonstrate that magnetic fluids can be used to develop active journal bearings.

  16. Enthalpy-based equation of state for highly porous materials employing modified soft sphere fluid model

    Science.gov (United States)

    Nayak, Bishnupriya; Menon, S. V. G.

    2018-01-01

    Enthalpy-based equation of state based on a modified soft sphere model for the fluid phase, which includes vaporization and ionization effects, is formulated for highly porous materials. Earlier developments and applications of enthalpy-based approach had not accounted for the fact that shocked states of materials with high porosity (e.g., porosity more than two for Cu) are in the expanded fluid region. We supplement the well known soft sphere model with a generalized Lennard-Jones formula for the zero temperature isotherm, with parameters determined from cohesive energy, specific volume and bulk modulus of the solid at normal condition. Specific heats at constant pressure, ionic and electronic enthalpy parameters and thermal excitation effects are calculated using the modified approach and used in the enthalpy-based equation of state. We also incorporate energy loss from the shock due to expansion of shocked material in calculating porous Hugoniot. Results obtained for Cu, even up to initial porosities ten, show good agreement with experimental data.

  17. Evaluation of some natural water-insoluble cellulosic material as lost circulation control additives in water-based drilling fluid

    Directory of Open Access Journals (Sweden)

    Ahmed Mohamed Alsabagh

    2015-12-01

    In this work, three natural water-insoluble cellulosic materials; peanut hulls, bagasse and sawdust were investigated as lost circulation control materials. One hundred and eight different LCM samples made of various materials were tested with mud. The experiments were conducted in a permeability plugging apparatus (PPA at a differential pressure of 100 psi and 300 psi, using 10, 60 and 90 ceramic discs. The performance of each LCM sample was determined based on the amount of spurt loss and total fluid loss of the mud according to the American Petroleum Institute (API standard. The obtained results showed that, the amount of the fluid loss depends on the LCM material, concentration and size distribution, testing results show that, the peanut gives the best results among the bagasse and sawdust, especially fine size which exhibited better results in the filtration characteristics due to the better filling properties of this size. Peanut hulls, bagasse and sawdust show a slight effect on the rheological properties of the mud. The results were discussed on light of particle size distribution.

  18. BDFGEOTHERM - A Swiss geothermal fluids database; BDFGEOTHERM - Base de donnees des fluides geothermiques de la Suisse - Rapport final

    Energy Technology Data Exchange (ETDEWEB)

    Sonney, R.; Vuataz, F.-D.

    2007-07-01

    The motivation to build up the database BDFGeotherm was to put at the disposal of the geothermal community a comprehensive set of data on the deep fluids of Switzerland and of some neighbouring areas. Researchers, engineers and all persons wanting to know the type and properties of geothermal fluids existing in a given area or underground system can find in BDFGeotherm a wealth of information which are generally widely dispersed and often difficult to reach. The BDFGeotherm database has been built under Microsoft ACCESS code and consists of nine tables connected with a primary key: the field 'Code'. A selection of parameters has been chosen from the following fields: general and geographical description, geology, hydrogeology, hydraulics, hydrochemistry and isotopes and finally geothermal parameters. Data implemented in BDFGeotherm are in numerical or in text format. Moreover, in the field 'Lithological log', one can visualize and save bitmap images containing lithological logs of boreholes. A total of 203 thermal springs or deep boreholes from 82 geothermal sites are implemented in BDFGeotherm. Among the 68 Swiss sites, a large majority of them are located in the northern part of the Jura range and in the upper Rhone valley (Wallis). Some sites, in Germany (5), France (3) and Italy (6), were selected for the following reasons: located near Swiss hot springs or deep boreholes, having similar geological features or representing a significant geothermal potential. Many types of queries could be realised, using any fields of the database and the results can be put into tables and printed or exported and saved in other files. (author)

  19. Fluid Sensor Based on Transmission Dip Caused by Mini Stop-Band in Photonic Crystal Slab

    International Nuclear Information System (INIS)

    Lei, Cao; Yi-Dong, Huang; Xiao-Yu, Mao; Fei, Li; Wei, Zhang; Jiang-De, Peng

    2008-01-01

    We propose a fluid sensor based on transmission dip caused by mini stop-band in photonic crystal slabs. Simulation results show that this novel type of sensors has large detective range (more than 1.5) and relative high-sensitivity (4.3 × 10 −5 in certain conditions). The central frequency and bandwidth of the mini stop-bands depend on the structure parameters of PC waveguides, which makes it possible to optimize the detective range and detective sensitivity. (fundamental areas of phenomenology (including applications))

  20. Performance Characteristics and Temperature Compensation Method of Fluid Property Sensor Based on Tuning-Fork Technology

    Directory of Open Access Journals (Sweden)

    Yuan Chen

    2016-01-01

    Full Text Available Fluid property sensor (FPS based on tuning-fork technology is applied to the measurement of the contaminant level of lubricant oil. The measuring principle of FPS sensor is derived and proved together with its resolution. The performance characteristics of the FPS sensor, such as sensitivity coefficient, resolution, and quality factor, are analyzed. A temperature compensation method is proposed to eliminate the temperature-dependence of the measuring parameters, and its validity is investigated by numerical simulation of sensitivity, oscillating frequency, and dielectric constant. The values of purification efficiency obtained using microwave and without microwave are compared experimentally.

  1. Fluid-structure interaction-based biomechanical perception model for tactile sensing.

    Directory of Open Access Journals (Sweden)

    Zheng Wang

    Full Text Available The reproduced tactile sensation of haptic interfaces usually selectively reproduces a certain object attribute, such as the object's material reflected by vibration and its surface shape by a pneumatic nozzle array. Tactile biomechanics investigates the relation between responses to an external load stimulus and tactile perception and guides the design of haptic interface devices via a tactile mechanism. Focusing on the pneumatic haptic interface, we established a fluid-structure interaction-based biomechanical model of responses to static and dynamic loads and conducted numerical simulation and experiments. This model provides a theoretical basis for designing haptic interfaces and reproducing tactile textures.

  2. Reliability Based Design of Fluid Power Pitch Systems for Wind Turbines

    DEFF Research Database (Denmark)

    Liniger, Jesper; N. Soltani, Mohsen; Pedersen, Henrik Clemmensen

    2017-01-01

    Priority Number. The Failure Mode and Effect Criticality Analysis is based on past research concerning failure analysis of wind turbine drive trains. Guidelines are given to select the severity, occurrence and detection score that make up the risk priority number. The usability of the method is shown...... in a case study of a fluid power pitch system applied to wind turbines. The results show a good agreement to recent field failure data for offshore turbines where the dominating failure modes are related to valves, accumulators and leakage. The results are further used for making design improvements...

  3. Night work, long work weeks, and risk of accidental injuries. A register-based study.

    Science.gov (United States)

    Larsen, Ann D; Hannerz, Harald; Møller, Simone V; Dyreborg, Johnny; Bonde, Jens Peter; Hansen, Johnni; Kolstad, Henrik A; Hansen, Åse Marie; Garde, Anne Helene

    2017-11-01

    Objectives The aims of this study were to (i) investigate the association between night work or long work weeks and the risk of accidental injuries and (ii) test if the association is affected by age, sex or socioeconomic status. Methods The study population was drawn from the Danish version of the European Labour Force Survey from 1999-2013. The current study was based on 150 438 participants (53% men and 47% women). Data on accidental injuries were obtained at individual level from national health registers. We included all 20-59-year-old employees working ≥32 hours a week at the time of the interview. We used Poisson regression to estimate the relative rates (RR) of accidental injuries as a function of night work or long work weeks (>40 hours per week) adjusted for year of interview, sex, age, socioeconomic status (SES), industry, and weekly working hours or night work. Age, sex and SES were included as two-way interactions. Results We observed 23 495 cases of accidental injuries based on 273 700 person years at risk. Exposure to night work was statistically significantly associated with accidental injuries (RR 1.11, 99% CI 1.06-1.17) compared to participants with no recent night work. No associations were found between long work weeks (>40 hours) and accidental injuries. Conclusion We found a modest increased risk of accidental injuries when reporting night work. No associations between long work weeks and risk of accidental injuries were observed. Age, sex and SES showed no trends when included as two-way interactions.

  4. Individual differences in satisfaction with activity-based work environments

    NARCIS (Netherlands)

    Hoendervanger, Jan; Ernst, Anja F.; Albers, Casper; Mobach, Mark; Van Yperen, Nico W.

    2018-01-01

    Satisfaction with activity-based work environments (ABW environments) often falls short of expectations, with striking differences among individual workers. A better understanding of these differences may provide clues for optimising satisfaction with ABW environments and associated organisational

  5. Problem-Based Learning in Social Work Education

    DEFF Research Database (Denmark)

    Monrad, Merete; Mølholt, Anne-Kirstine

    2017-01-01

    ’ experiences of PBL. In this article we address this gap by exploring experiences of learning and learning preferences among master’s-level students in a Danish social work education setting where extensive problem-based project work is used. We find a discrepancy between students’ preferred learning and when...

  6. Work hardening correlation for monotonic loading based on state variables

    International Nuclear Information System (INIS)

    Huang, F.H.; Li, C.Y.

    1977-01-01

    An absolute work hardening correlation in terms of the hardness parameter and the internal stress based on the state variable approach was developed. It was found applicable to a variety of metals and alloys. This correlation predicts strain rate insensitive work hardening properties at low homologous temperatures and produces strain rate effects at higher homologous temperatures without involving thermally induced recovery processes

  7. In situ Raman-based detections of the hydrothermal vent and cold seep fluids

    Science.gov (United States)

    Zhang, Xin; Du, Zengfeng; Zheng, Ronger; Luan, Zhendong; Qi, Fujun; Cheng, Kai; Wang, Bing; Ye, Wangquan; Liu, Xiaorui; Chen, Changan; Guo, Jinjia; Li, Ying; Yan, Jun

    2016-04-01

    Hydrothermal vents and cold seeps, and their associated biological communities play an important role in global carbon and sulphur biogeochemical cycles. Most of the studies of fluid composition geochemistry are based on recovered samples, both with gas-tight samplers and as open specimens, but the in situ conditions are difficult to maintain in recovered samples. Determination in situ of the chemical signals of the emerging fluids are challenging due to the high pressure, often strongly acidic and temperature in which few sensors can survive. Most of those sensors used so far are based on electrochemistry, and can typically detect only a few chemical species. Here we show that direct measurement of critical chemical species of hydrothermal vents and cold seeps can be made rapidly and in situ by means of a new hybrid version of earlier deep-sea pore water Raman probe carried on the ROV (Remote Operated Vehicle) Faxian. The fluid was drawn through the probe by actuating a hydraulic pump on the ROV, and measured at the probe optical cell through a sapphire window. We have observed the concentrations of H2S, HS-, SO42-, HSO4-, CO2, and H2 in hydrothermal vent fluids from the Pacmanus and Desmos vent systems in the Manus back-arc basin, Papua New Guinea. Two black smokers (279° C and 186° C) at the Pacmanus site showed the characteristic loss of SO42-, and the increase of CO2 and well resolved H2S and HS- peaks. At the white smoker of Onsen site the strong HSO4-peak observed at high temperature quickly dropped with strong accompanying increase of SO42-and H2 peaks when the sample contained in the Raman sensing cell was removed from the hot fluid due to rapid thermal deprotonation. We report here also the finding of a new lower temperature (88° C) white smoker "Kexue" field at the Desmos site with strong H2S, HS- and CO2 signals. We also have detected the concentrations of CH4,H2S, HS-, SO42-, and S8 in cold seep fluids and the surrounding sediment pore water from

  8. Waste Contaminants at Military Bases Working Group report

    International Nuclear Information System (INIS)

    1993-01-01

    The Waste Contaminants at Military Bases Working Group has screened six prospective demonstration projects for consideration by the Federal Advisory Committee to Develop On-Site Innovative Technologies (DOIT). These projects include the Kirtland Air Force Base Demonstration Project, the March Air Force Base Demonstration Project, the McClellan Air Force Base Demonstration Project, the Williams Air Force Base Demonstration Project, and two demonstration projects under the Air Force Center for Environmental Excellence. A seventh project (Port Hueneme Naval Construction Battalion Center) was added to list of prospective demonstrations after the September 1993 Working Group Meeting. This demonstration project has not been screened by the working group. Two additional Air Force remediation programs are also under consideration and are described in Section 6 of this document. The following information on prospective demonstrations was collected by the Waste Contaminants at Military Bases Working Group to assist the DOIT Committee in making Phase 1 Demonstration Project recommendations. The remainder of this report is organized into seven sections: Work Group Charter's mission and vision; contamination problems, current technology limitations, and institutional and regulatory barriers to technology development and commercialization, and work force issues; screening process for initial Phase 1 demonstration technologies and sites; demonstration descriptions -- good matches;demonstration descriptions -- close matches; additional candidate demonstration projects; and next steps

  9. Difference of Work Satisfaction on Teachers Based on Gender Leadership

    OpenAIRE

    Era Wati, Susi Endang; Suparno, Suparno; Yunita, Rosana Dewi

    2007-01-01

    The aim of this research is to know the difference of work satisfaction based on gender leadership. The participants of this research is 48 teachers from SMP Negeri 2 Kartasura and SMP Negeri 3 Kartasura. The result of this research shows t-test about 3,348 (p < 0.01). It tells us about the difference of work satisfaction based on gender leadership which is the empiric mean for male leadership around 143,652 and for female leadership around 128,990. This result shows that teacher work satisfa...

  10. The fluid–solid coupling analysis of screw conveyor in drilling fluid centrifuge based on ANSYS

    Directory of Open Access Journals (Sweden)

    Hongbin Liu

    2015-09-01

    Full Text Available In the centrifugal separations of drilling fluid, screw conveyor is a critical component to push and separate the sediment. The work performance and structural parameters of conveyor are immediately related to the production capability, the working life and the separating effect of the centrifuge. The existing researches always use the theoretical calculation of the approximate loads to analyze the strength of conveyor, and it cannot reflect the stress situations accurately. In order to ensure the precise mastery of the working performance, this article obtained pressure distribution under working conditions from CFX evaluation and gained equivalent stress and deformation under several load conditions by using the ANSYS Workbench platform to check the strength of conveyor. The results showed that the influence of centrifugal hydraulic pressure was less than that of centrifugal force on the strength and deformation of conveyor. Besides, the maximum equivalent stress occurred at the inside of the feed opening, while the maximum deformation occurred at the conveyor blade edge of taper extremity. Furthermore, whether considered the feed opening or not, the computing model had a great influence on the analysis results, and the simplified loads had a great influence on the deformation analysis results. The methods and results from this article can provide reference for the design and the improvement of screw conveyor.

  11. A study on the performance of condensation heat transfer for various working fluid of two-phase closed thermosyphons with various helical grooves

    International Nuclear Information System (INIS)

    Han, Kyu Il; Cho, Dong Hyun

    2005-01-01

    This study concerns the performance of condensing heat transfer in two-phase closed thermosyphons with various helical grooves. Distilled water, methanol, ethanol have been used as the working fluid. In the present work, a copper tube of the length of 1200mm and 14.28mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550mm, while the remaining part of the thermosyphon tube is adiabatic section. A experimental study was carried out for analyzing the performances of having 50, 60, 70, 80, 90 helical grooves. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphons is also tested for the comparison. The type of working fluid and the numbers of grooves of the thermosyphons with various helical grooves have been used as the experimental parameters. The experimental results have been assessed and compared with existing theories. The results show that the type of working fluids are very important factors for the operation of thermosyphons. And the maximum enhancement (i.e. the ratio of the heat transfer coefficients the helical thermosyphons to plain thermosyphons) is 1.5∼2 for condensation

  12. An agent-based method for simulating porous fluid-saturated structures with indistinguishable components

    Science.gov (United States)

    Kashani, Jamal; Pettet, Graeme John; Gu, YuanTong; Zhang, Lihai; Oloyede, Adekunle

    2017-10-01

    Single-phase porous materials contain multiple components that intermingle up to the ultramicroscopic level. Although the structures of the porous materials have been simulated with agent-based methods, the results of the available methods continue to provide patterns of distinguishable solid and fluid agents which do not represent materials with indistinguishable phases. This paper introduces a new agent (hybrid agent) and category of rules (intra-agent rule) that can be used to create emergent structures that would more accurately represent single-phase structures and materials. The novel hybrid agent carries the characteristics of system's elements and it is capable of changing within itself, while also responding to its neighbours as they also change. As an example, the hybrid agent under one-dimensional cellular automata formalism in a two-dimensional domain is used to generate patterns that demonstrate the striking morphological and characteristic similarities with the porous saturated single-phase structures where each agent of the ;structure; carries semi-permeability property and consists of both fluid and solid in space and at all times. We conclude that the ability of the hybrid agent to change locally provides an enhanced protocol to simulate complex porous structures such as biological tissues which could facilitate models for agent-based techniques and numerical methods.

  13. The effect of functionalized silver nanoparticles over the thermal conductivity of base fluids

    Science.gov (United States)

    Seyhan, Merve; Altan, Cem Levent; Gurten, Berna; Bucak, Seyda

    2017-04-01

    Thermal conductivities of nanofluids are expected to be higher than common heat transfer fluids. The use of metal nanoparticles has not been intensely investigated for heat transfer applications due to lack of stability. Here we present an experimental study on the effect of silver nanoparticles (Ag NPs) which are stabilized with surfactants, on the thermal conductivity of water, ethylene glycol and hexane. Hydrophilic Ag NPs were synthesized in aqueous medium with using gum arabic as surfactant and oleic acid/oleylamine were used to stabilize Ag NPs in the organic phase. The enhancement up to 10 per cent in effective thermal conductivity of hexane and ethylene glycol was achieved with addition of Ag NPs at considerably low concentrations (i.e. 2 and 1 per cent, by weight, for hexane and ethylene glycol respectively). However, almost 10 per cent of deterioration was recorded at effective thermal conductivity of water when Ag NPs were added at 1 per cent (by wt). Considerable amount of Gum Arabic in the medium is shown to be the major contributor to this fall, causing lowering of thermal conductivity of water. Same particles performed much better in ethylene glycol where the stabilizer does not lower the thermal conductivity of the base fluid. Also thermal conductivity of nanofluids was found to be temperature independent except water based Ag nanofluids above a threshold concentration. This temperature dependency is suggested to be due to inhibition of hydrogen bonding among water molecules in the presence of high amounts of gum arabic.

  14. a New ER Fluid Based Haptic Actuator System for Virtual Reality

    Science.gov (United States)

    Böse, H.; Baumann, M.; Monkman, G. J.; Egersdörfer, S.; Tunayar, A.; Freimuth, H.; Ermert, H.; Khaled, W.

    The concept and some steps in the development of a new actuator system which enables the haptic perception of mechanically inhomogeneous virtual objects are introduced. The system consists of a two-dimensional planar array of actuator elements containing an electrorheological (ER) fluid. When a user presses his fingers onto the surface of the actuator array, he perceives locally variable resistance forces generated by vertical pistons which slide in the ER fluid through the gaps between electrode pairs. The voltage in each actuator element can be individually controlled by a novel sophisticated switching technology based on optoelectric gallium arsenide elements. The haptic information which is represented at the actuator array can be transferred from a corresponding sensor system based on ultrasonic elastography. The combined sensor-actuator system may serve as a technology platform for various applications in virtual reality, like telemedicine where the information on the consistency of tissue of a real patient is detected by the sensor part and recorded by the actuator part at a remote location.

  15. Physically based model for extracting dual permeability parameters using non-Newtonian fluids

    Science.gov (United States)

    Abou Najm, M. R.; Basset, C.; Stewart, R. D.; Hauswirth, S.

    2017-12-01

    Dual permeability models are effective for the assessment of flow and transport in structured soils with two dominant structures. The major challenge to those models remains in the ability to determine appropriate and unique parameters through affordable, simple, and non-destructive methods. This study investigates the use of water and a non-Newtonian fluid in saturated flow experiments to derive physically-based parameters required for improved flow predictions using dual permeability models. We assess the ability of these two fluids to accurately estimate the representative pore sizes in dual-domain soils, by determining the effective pore sizes of macropores and micropores. We developed two sub-models that solve for the effective macropore size assuming either cylindrical (e.g., biological pores) or planar (e.g., shrinkage cracks and fissures) pore geometries, with the micropores assumed to be represented by a single effective radius. Furthermore, the model solves for the percent contribution to flow (wi) corresponding to the representative macro and micro pores. A user-friendly solver was developed to numerically solve the system of equations, given that relevant non-Newtonian viscosity models lack forms conducive to analytical integration. The proposed dual-permeability model is a unique attempt to derive physically based parameters capable of measuring dual hydraulic conductivities, and therefore may be useful in reducing parameter uncertainty and improving hydrologic model predictions.

  16. Dissipativity analysis of the base isolated benchmark structure with magnetorheological fluid dampers

    International Nuclear Information System (INIS)

    Erkus, Baris; Johnson, Erik A

    2011-01-01

    This paper investigates the dissipativity and performance characteristics of the semiactive control of the base isolated benchmark structure with magnetorheological (MR) fluid dampers. Previously, the authors introduced the concepts of dissipativity and dissipativity indices in the semiactive control of structures with smart dampers and studied the dissipativity characteristics of simple structures with idealized dampers. To investigate the effects of semiactive controller dissipativity characteristics on the overall performance of the base isolated benchmark building, a clipped optimal control strategy with a linear quadratic Gaussian (LQG) controller and a 20 ton MR fluid damper model is used. A cumulative index is proposed for quantifying the overall dissipativity of a control system with multiple control devices. Two control designs with different dissipativity and performance characteristics are considered as the primary controller in clipped optimal control. Numerical simulations reveal that the dissipativity indices can be classified into two groups that exhibit distinct patterns. It is shown that the dissipativity indices identify primary controllers that are more suitable for application with MR dampers and provide useful information in the semiactive design process that complements other performance indices. The computational efficiency of the proposed dissipativity indices is verified by comparing computation times

  17. What is the future of work based learning in VET?

    DEFF Research Database (Denmark)

    Jørgensen, Christian Helms

    not to pursue an academic career. Countries with strong apprenticeship systems tend to have less youth unemployment and a smoother transition to the labour market than others. Furthermore, from a learning perspective, the outcomes of work-based training and informal learning are enhanced when they are combined...... that question the future role and organisation of work-based training in VET. The purpose of this paper is to examine these challenges based on a review of research on European VET systems and analyses of the Danish dual system of VET. In the end of the paper, some innovative solutions to these challenges...

  18. Highly sensitive magnetic field sensor based on microfiber coupler with magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Longfeng; Pu, Shengli, E-mail: shlpu@usst.edu.cn; Tang, Jiali [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zeng, Xianglong [2Key Laboratory of Specialty Fiber Optics and Optical Access Network, Shanghai University, Shanghai 200072 (China); Lahoubi, Mahieddine [Department of Physics, Faculty of Sciences, Laboratory L.P.S., Badji Mokhtar-Annaba University, P. O. Box 12, 23000 Annaba (Algeria)

    2015-05-11

    A kind of magnetic field sensor using a microfiber coupler (MFC) surrounded with magnetic fluid (MF) is proposed and experimentally demonstrated. As the MFC is strongly sensitive to the surrounding refractive index (RI) and MF's RI is sensitive to magnetic field, the magnetic field sensing function of the proposed structure is realized. Interrogation of magnetic field strength is achieved by measuring the dip wavelength shift and transmission loss change of the transmission spectrum. The experimental results show that the sensitivity of the sensor is wavelength-dependent. The maximum sensitivity of 191.8 pm/Oe is achieved at wavelength of around 1537 nm in this work. In addition, a sensitivity of −0.037 dB/Oe is achieved by monitoring variation of the fringe visibility. These suggest the potential applications of the proposed structure in tunable all-in-fiber photonic devices such as magneto-optical modulator, filter, and sensing.

  19. Highly sensitive magnetic field sensor based on microfiber coupler with magnetic fluid

    International Nuclear Information System (INIS)

    Luo, Longfeng; Pu, Shengli; Tang, Jiali; Zeng, Xianglong; Lahoubi, Mahieddine

    2015-01-01

    A kind of magnetic field sensor using a microfiber coupler (MFC) surrounded with magnetic fluid (MF) is proposed and experimentally demonstrated. As the MFC is strongly sensitive to the surrounding refractive index (RI) and MF's RI is sensitive to magnetic field, the magnetic field sensing function of the proposed structure is realized. Interrogation of magnetic field strength is achieved by measuring the dip wavelength shift and transmission loss change of the transmission spectrum. The experimental results show that the sensitivity of the sensor is wavelength-dependent. The maximum sensitivity of 191.8 pm/Oe is achieved at wavelength of around 1537 nm in this work. In addition, a sensitivity of −0.037 dB/Oe is achieved by monitoring variation of the fringe visibility. These suggest the potential applications of the proposed structure in tunable all-in-fiber photonic devices such as magneto-optical modulator, filter, and sensing

  20. A warning system based on the RFID technology for running-out of injection fluid.

    Science.gov (United States)

    Huang, Chi-Fang; Lin, Jen-Hung

    2011-01-01

    For providing an automatic warning system of running-out of injection fluid, RFID technology is applied in this work to propose an infrastructure with low cost to help nurses and patient's company. Specially, a RFID tag is designed and attached on a bag of intravenous drip to demonstrate the benefits in the present system. The main idea of this system is that, tag is disabled when the bag is not empty because of the EM loading due to the liquid contained. The bag can be any kind in the current market and be without any electronic attachment or modification. LAN (Local Area Network) is also applied as a part of this infrastructure for data transmission.

  1. Dynamic Behavior Analysis of Non-Contacting Hydrodynamic Finger Seal Based on Fluid-Solid-Interaction Method

    Directory of Open Access Journals (Sweden)

    Su Hua

    2018-01-01

    Full Text Available Finger seal is an advanced compliant seal and can be utilized to separate high (HP and low pressure (LP zones in high speed rotating shaft environment. The work to be presented concerns the dynamic behavior of a repetitive section of a two-layer finger seal with high-and padded low-pressure laminates. The dynamic performance of the finger seal are analyzed by the coupled fluid-solid-interaction (FSI simulations. By using the commercial software ANSYS-CFX, the numerical simulation results of interactions between the gas flow and fingers structural deformation are described when the radial periodic excitation from the shaft applies to the finger seal. And the gas film loading capacity, gas film stiffness and leakage varied with time are put forward in different working conditions. Compared with the dynamic performance analysis results based on equivalent dynamic method, the FSI dynamic analysis shows some different characteristics which are more accordance with actual circumstance. Moreover, it is shown that under low pressure differential and high rotation speed the non-contacting finger seal with advance features both in sealing effectiveness and potential unlimited life span can be obtained by rational structure design. But for the non-contacting finger seal with circumferential convergent pad working in high pressure and low rotating speed conditions, it is difficult to improve the sealing performance by the way of changing the structure parameters of finger seal. It is because the high pressure plays a major role on this sealing situation.

  2. Numerical simulation of countercurrent flow based on two-fluid model

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.D. [Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai 519082 (China); School of Electric Power, South China University of Technology, Guangzhou 510640 (China); Zhang, X.Y., E-mail: zxiaoying@mail.sysu.edu.cn [Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai 519082 (China)

    2017-03-15

    Highlights: • Using one-dimensional two-fluid model to help understanding counter-current flow two-phase flows. • Using surface tension model to make the one-dimensional two-fluid flow model well-posed. • Solving the governing equations with a modified SIMPLE algorithm. • Validating code with experimental data and applying it to vertical air/steam countercurrent flow condition - Abstract: In order to improve the understanding of counter-current two-phase flows, a transient analysis code is developed based on one-dimensional two-fluid model. A six equation model has been established and a two phase pressure model with surface tension term, wall drag force and interface shear terms have been used. Taking account of transport phenomenon, heat and mass transfer models of interface were incorporated. The staggered grids have been used in discretization of equations. For validation of the model and code, a countercurrent air-water problem in one experimental horizontal stratified flow has been considered firstly. Comparison of the computed results and the experimental one shows satisfactory agreement. As the full problem for investigation, one vertical pipe with countercurrent flow of steam-water and air-water at same boundary condition has been taken for study. The transient distribution of liquid fraction, liquid velocity and gas velocity for selected positions of steam-water and air-water problem were presented and discussed. The results show that these two simulations have similar transient behavior except that the distribution of gas velocity for steam-water problem have larger oscillation than the one for air-water. The effect of mesh size on wavy characteristics of interface surface was also investigated. The mesh size has significant influence on the simulated results. With the increased refinement, the oscillation gets stronger.

  3. Evaluation on the Presence of Nano Silver Particle in Improving a Conventional Water-based Drilling Fluid

    Science.gov (United States)

    Husin, H.; Ahmad, N.; Jamil, N.; Chyuan, O. H.; Roslan, A.

    2018-05-01

    Worldwide demand in oil and gas energy consumption has been driving many of oil and gas companies to explore new oil and gas resource field in an ultra-deep water environment. As deeper well is drilled, more problems and challenges are expected. The successful of drilling operation is highly dependent on properties of drilling fluids. As a way to operate drilling in challenging and extreme surroundings, nanotechnology with their unique properties is employed. Due to unique physicochemical, electrical, thermal, hydrodynamic properties and exceptional interaction potential of nanomaterials, nanoparticles are considered to be the most promising material of choice for smart fluid design for oil and gas field application. Throughout this paper, the effect of nano silver particle in improving a conventional water based drilling fluid was evaluated. Results showed that nano silver gave a significant improvement to the conventional water based drilling fluid in terms of its rheological properties and filtration test performance.

  4. Performance Testing of Cutting Fluids

    DEFF Research Database (Denmark)

    Belluco, Walter

    The importance of cutting fluid performance testing has increased with documentation requirements of new cutting fluid formulations based on more sustainable products, as well as cutting with minimum quantity of lubrication and dry cutting. Two sub-problems have to be solved: i) which machining...... tests feature repeatability, reproducibility and sensitivity to cutting fluids, and ii) to what extent results of one test ensure relevance to a wider set of machining situations. The present work is aimed at assessing the range of validity of the different testing methods, investigating correlation...... within the whole range of operations, materials, cutting fluids, operating conditions, etc. Cutting fluid performance was evaluated in turning, drilling, reaming and tapping, and with respect to tool life, cutting forces, chip formation and product quality (dimensional accuracy and surface integrity...

  5. Computational Fluid Dynamic Modeling of Rocket Based Combined Cycle Engine Flowfields

    Science.gov (United States)

    Daines, Russell L.; Merkle, Charles L.

    1994-01-01

    Computational Fluid Dynamic techniques are used to study the flowfield of a fixed geometry Rocket Based Combined Cycle engine operating in rocket ejector mode. Heat addition resulting from the combustion of injected fuel causes the subsonic engine flow to choke and go supersonic in the slightly divergent combustor-mixer section. Reacting flow computations are undertaken to predict the characteristics of solutions where the heat addition is determined by the flowfield. Here, adaptive gridding is used to improve resolution in the shear layers. Results show that the sonic speed is reached in the unheated portions of the flow first, while the heated portions become supersonic later. Comparison with results from another code show reasonable agreement. The coupled solutions show that the character of the combustion-based thermal choking phenomenon can be controlled reasonably well such that there is opportunity to optimize the length and expansion ratio of the combustor-mixer.

  6. Finite element analysis-based design of a fluid-flow control nano-valve

    International Nuclear Information System (INIS)

    Grujicic, M.; Cao, G.; Pandurangan, B.; Roy, W.N.

    2005-01-01

    A finite element method-based procedure is developed for the design of molecularly functionalized nano-size devices. The procedure is aimed at the single-walled carbon nano-tubes (SWCNTs) used in the construction of such nano-devices and utilizes spatially varying nodal forces to represent electrostatic interactions between the charged groups of the functionalizing molecules. The procedure is next applied to the design of a fluid-flow control nano-valve. The results obtained suggest that the finite element-based procedure yields the results, which are very similar to their molecular modeling counterparts for small-size nano-valves, for which both types of analyses are feasible. The procedure is finally applied to optimize the design of a larger-size nano-valve, for which the molecular modeling approach is not practical

  7. Corrosion of Nickel-Based Alloys in Ultra-High Temperature Heat Transfer Fluid

    Science.gov (United States)

    Wang, Tao; Reddy, Ramana G.

    2017-03-01

    MgCl2-KCl binary system has been proposed to be used as high temperature reactor coolant. Due to its relatively low melting point, good heat capacity and excellent thermal stability, this system can also be used in high operation temperature concentrating solar power generation system as heat transfer fluid (HTF). The corrosion behaviors of nickel based alloys in MgCl2-KCl molten salt system at 1,000 °C were determined based on long-term isothermal dipping test. After 500 h exposure tests under strictly maintained high purity argon gas atmosphere, the weight loss and corrosion rate analysis were conducted. Among all the tested samples, Ni-201 demonstrated the lowest corrosion rate due to the excellent resistance of Ni to high temperature element dissolution. Detailed surface topography and corrosion mechanisms were also determined by using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS).

  8. Poly(butylene terephthalate) based novel achiral stationary phase investigated under supercritical fluid chromatography conditions.

    Science.gov (United States)

    Nagai, Kanji; Shibata, Tohru; Shinkura, Satoshi; Ohnishi, Atsushi

    2018-05-11

    Poly(butylene terephthalate) based novel stationary phase (SP), composed of planar aromatic phenyl group together with ester group monomer units, was designed for supercritical fluid chromatography (SFC) use. As expected from its structure, this phase shows planarity recognition of isomeric aromatics and closely similar compounds. Interestingly, for most analytes, the retention behavior of this SP is significantly distinct from that of the 2-ethylpyridine based SPs which is among the most well-known SFC dedicated phases. Although the poly(butylene terephthalate) is coated on silica gel, the performance of the column did not change by using extended range modifiers such as THF, dichloromethane or ethyl acetate and column robustness was confirmed by cycle durability testing. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Rule-Based Multidisciplinary Tool for Unsteady Reacting Real-Fluid Flows, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Loci-STREAM is a CFD-based, multidisciplinary, high-fidelity design and analysis tool resulting from Phase I work whose objectives were: (a) to demonstrate the...

  10. Fluid dynamics

    CERN Document Server

    Bernard, Peter S

    2015-01-01

    This book presents a focused, readable account of the principal physical and mathematical ideas at the heart of fluid dynamics. Graduate students in engineering, applied math, and physics who are taking their first graduate course in fluids will find this book invaluable in providing the background in physics and mathematics necessary to pursue advanced study. The book includes a detailed derivation of the Navier-Stokes and energy equations, followed by many examples of their use in studying the dynamics of fluid flows. Modern tensor analysis is used to simplify the mathematical derivations, thus allowing a clearer view of the physics. Peter Bernard also covers the motivation behind many fundamental concepts such as Bernoulli's equation and the stream function. Many exercises are designed with a view toward using MATLAB or its equivalent to simplify and extend the analysis of fluid motion including developing flow simulations based on techniques described in the book.

  11. MEASURING WORKING HOURS INPUT IN VINE GROWING AT WORK ORGANIZATION BASED ON PHENOLOGICAL PHASES

    Directory of Open Access Journals (Sweden)

    J BRAZSIL

    2002-05-01

    Full Text Available Research was based on phenological phases of Italian Riesling, involving differences in labour and financial input for dry, optimal and wet weather. Worktime demand for certain operations in vine growing was determined with an analytic method, work day survey and We worked out alternatives for dry, optimum and wet weather on the basis of phenological phaseses. The worktime demand for the phenological phases with all their operations were analysed and planned in an itemized way based on our findings. We used them to work out the worktime demand for the given vine land for each operation. To analyse differences coming from diverse methods of cultivation and spacing, the material, operational and total costs of hand and mechanized labour were projected for 1 hectare and variance analysis was made.

  12. Gripping characteristics of an electromagnetically activated magnetorheological fluid-based gripper

    Science.gov (United States)

    Choi, Young T.; Hartzell, Christine M.; Leps, Thomas; Wereley, Norman M.

    2018-05-01

    The design and test of a magnetorheological fluid (MRF)-based universal gripper (MR gripper) are presented in this study. The MR gripper was developed to have a simple design, but with the ability to produce reliable gripping and handling of a wide range of simple objects. The MR gripper design consists of a bladder mounted atop an electromagnet, where the bladder is filled with an MRF, which was formulated to have long-term stable sedimentation stability, that was synthesized using a high viscosity linear polysiloxane (HVLP) carrier fluid with a carbonyl iron particle (CIP) volume fraction of 35%. Two bladders were fabricated: a magnetizable bladder using a magnetorheological elastomer (MRE), and a passive (non-magnetizable) silicone rubber bladder. The holding force and applied (initial compression) force of the MR gripper for a bladder fill volume of 75% were experimentally measured, for both magnetizable and passive bladders, using a servohydraulic material testing machine for a range of objects. The gripping performance of the MR gripper using an MRE bladder was compared to that of the MR gripper using a passive bladder.

  13. Fluid pipeline system leak detection based on neural network and pattern recognition

    International Nuclear Information System (INIS)

    Tang Xiujia

    1998-01-01

    The mechanism of the stress wave propagation along the pipeline system of NPP, caused by turbulent ejection from pipeline leakage, is researched. A series of characteristic index are described in time domain or frequency domain, and compress numerical algorithm is developed for original data compression. A back propagation neural networks (BPNN) with the input matrix composed by stress wave characteristics in time domain or frequency domain is first proposed to classify various situations of the pipeline, in order to detect the leakage in the fluid flow pipelines. The capability of the new method had been demonstrated by experiments and finally used to design a handy instrument for the pipeline leakage detection. Usually a pipeline system has many inner branches and often in adjusting dynamic condition, it is difficult for traditional pipeline diagnosis facilities to identify the difference between inner pipeline operation and pipeline fault. The author first proposed pipeline wave propagation identification by pattern recognition to diagnose pipeline leak. A series of pattern primitives such as peaks, valleys, horizon lines, capstan peaks, dominant relations, slave relations, etc., are used to extract features of the negative pressure wave form. The context-free grammar of symbolic representation of the negative wave form is used, and a negative wave form parsing system with application to structural pattern recognition based on the representation is first proposed to detect and localize leaks of the fluid pipelines

  14. A Multi-Phase Based Fluid-Structure-Microfluidic interaction sensor for Aerodynamic Shear Stress

    Science.gov (United States)

    Hughes, Christopher; Dutta, Diganta; Bashirzadeh, Yashar; Ahmed, Kareem; Qian, Shizhi

    2014-11-01

    A novel innovative microfluidic shear stress sensor is developed for measuring shear stress through multi-phase fluid-structure-microfluidic interaction. The device is composed of a microfluidic cavity filled with an electrolyte liquid. Inside the cavity, two electrodes make electrochemical velocimetry measurements of the induced convection. The cavity is sealed with a flexible superhydrophobic membrane. The membrane will dynamically stretch and flex as a result of direct shear cross-flow interaction with the seal structure, forming instability wave modes and inducing fluid motion within the microfluidic cavity. The shear stress on the membrane is measured by sensing the induced convection generated by membrane deflections. The advantages of the sensor over current MEMS based shear stress sensor technology are: a simplified design with no moving parts, optimum relationship between size and sensitivity, no gaps such as those created by micromachining sensors in MEMS processes. We present the findings of a feasibility study of the proposed sensor including wind-tunnel tests, microPIV measurements, electrochemical velocimetry, and simulation data results. The study investigates the sensor in the supersonic and subsonic flow regimes. Supported by a NASA SBIR phase 1 contract.

  15. Finite Element Analysis of Mechanical Characteristics of Dropped Eggs Based on Fluid-Solid Coupling Theory

    Directory of Open Access Journals (Sweden)

    Song Haiyan

    2017-01-01

    Full Text Available It is important to study the properties and mechanics of egg drop impacts in order to reduce egg loss during processing and logistics and to provide a basis for the protective packaging of egg products. In this paper, we present the results of our study of the effects of the structural parameters on the mechanical properties of an egg using a finite element model of the egg. Based on Fluid-Solid coupling theory, a finite element model of an egg was constructed using ADINA, a finite element calculation and analysis software package. To simplify the model, the internal fluid of the egg was considered to be a homogeneous substance. The egg drop impact was simulated by the coupling solution, and the feasibility of the model was verified by comparison with the experimental results of a drop test. In summary, the modeling scheme was shown to be feasible and the simulation results provide a theoretical basis for the optimum design of egg packaging and egg processing equipment.

  16. Work-Based Learning and Academic Skills. IEE Working Paper No. 15.

    Science.gov (United States)

    Hughes, Katherine L.; Moore, David Thornton; Bailey, Thomas R.

    The claim that work-based experience improves students' academic performance was examined through a study of the academic progress of 25 high school and community college student interns employed in various health care workplaces. Data were collected from the following activities: (1) review of the literature on academic reinforcement and academic…

  17. Teaching about Faith-Based Organizations in the Social Work Curriculum: Perspectives of Social Work Educators

    Science.gov (United States)

    Pandya, Samta P.

    2016-01-01

    Faith-based organizations (FBOs) have an important presence in contemporary civil society and have gained further prominence through their repertoire of social welfare and services. This study engaged social work educators (n = 316) across nine countries to examine their perceptions of including discourses on faith and FBOs in the social work…

  18. Two-body perturbation theory versus first order perturbation theory: A comparison based on the square-well fluid.

    Science.gov (United States)

    Mercier Franco, Luís Fernando; Castier, Marcelo; Economou, Ioannis G

    2017-12-07

    We show that the Zwanzig first-order perturbation theory can be obtained directly from a truncated Taylor series expansion of a two-body perturbation theory and that such truncation provides a more accurate prediction of thermodynamic properties than the full two-body perturbation theory. This unexpected result is explained by the quality of the resulting approximation for the fluid radial distribution function. We prove that the first-order and the two-body perturbation theories are based on different approximations for the fluid radial distribution function. To illustrate the calculations, the square-well fluid is adopted. We develop an analytical expression for the two-body perturbed Helmholtz free energy for the square-well fluid. The equation of state obtained using such an expression is compared to the equation of state obtained from the first-order approximation. The vapor-liquid coexistence curve and the supercritical compressibility factor of a square-well fluid are calculated using both equations of state and compared to Monte Carlo simulation data. Finally, we show that the approximation for the fluid radial distribution function given by the first-order perturbation theory provides closer values to the ones calculated via Monte Carlo simulations. This explains why such theory gives a better description of the fluid thermodynamic behavior.

  19. Enantioselective potential of polysaccharide-based chiral stationary phases in supercritical fluid chromatography.

    Science.gov (United States)

    Kucerova, Gabriela; Kalikova, Kveta; Tesarova, Eva

    2017-06-01

    The enantioselective potential of two polysaccharide-based chiral stationary phases for analysis of chiral structurally diverse biologically active compounds was evaluated in supercritical fluid chromatography using a set of 52 analytes. The chiral selectors immobilized on 2.5 μm silica particles were tris-(3,5-dimethylphenylcarmabate) derivatives of cellulose or amylose. The influence of the polysaccharide backbone, different organic modifiers, and different mobile phase additives on retention and enantioseparation was monitored. Conditions for fast baseline enantioseparation were found for the majority of the compounds. The success rate of baseline and partial enantioseparation with cellulose-based chiral stationary phase was 51.9% and 15.4%, respectively. Using amylose-based chiral stationary phase we obtained 76.9% of baseline enantioseparations and 9.6% of partial enantioseparations of the tested compounds. The best results on cellulose-based chiral stationary phase were achieved particularly with propane-2-ol and a mixture of isopropylamine and trifluoroacetic acid as organic modifier and additive to CO 2 , respectively. Methanol and basic additive isopropylamine were preferred on amylose-based chiral stationary phase. The complementary enantioselectivity of the cellulose- and amylose-based chiral stationary phases allows separation of the majority of the tested structurally different compounds. Separation systems were found to be directly applicable for analyses of biologically active compounds of interest. © 2017 Wiley Periodicals, Inc.

  20. Coupled in silico platform: Computational fluid dynamics (CFD) and physiologically-based pharmacokinetic (PBPK) modelling.

    Science.gov (United States)

    Vulović, Aleksandra; Šušteršič, Tijana; Cvijić, Sandra; Ibrić, Svetlana; Filipović, Nenad

    2018-02-15

    One of the critical components of the respiratory drug delivery is the manner in which the inhaled aerosol is deposited in respiratory tract compartments. Depending on formulation properties, device characteristics and breathing pattern, only a certain fraction of the dose will reach the target site in the lungs, while the rest of the drug will deposit in the inhalation device or in the mouth-throat region. The aim of this study was to link the Computational fluid dynamics (CFD) with physiologically-based pharmacokinetic (PBPK) modelling in order to predict aerolisolization of different dry powder formulations, and estimate concomitant in vivo deposition and absorption of amiloride hydrochloride. Drug physicochemical properties were experimentally determined and used as inputs for the CFD simulations of particle flow in the generated 3D geometric model of Aerolizer® dry powder inhaler (DPI). CFD simulations were used to simulate air flow through Aerolizer® inhaler and Discrete Phase Method (DPM) was used to simulate aerosol particles deposition within the fluid domain. The simulated values for the percent emitted dose were comparable to the values obtained using Andersen cascade impactor (ACI). However, CFD predictions indicated that aerosolized DPI have smaller particle size and narrower size distribution than assumed based on ACI measurements. Comparison with the literature in vivo data revealed that the constructed drug-specific PBPK model was able to capture amiloride absorption pattern following oral and inhalation administration. The PBPK simulation results, based on the CFD generated particle distribution data as input, illustrated the influence of formulation properties on the expected drug plasma concentration profiles. The model also predicted the influence of potential changes in physiological parameters on the extent of inhaled amiloride absorption. Overall, this study demonstrated the potential of the combined CFD-PBPK approach to model inhaled drug

  1. Acid-Base and Plasma Biochemical Changes Using Crystalloid Fluids in Stranded Juvenile Loggerhead Sea Turtles (Caretta caretta).

    Science.gov (United States)

    Camacho, María; Quintana, María Del Pino; Calabuig, Pascual; Luzardo, Octavio P; Boada, Luis D; Zumbado, Manuel; Orós, Jorge

    2015-01-01

    The aim of this study was to compare the efficacy and effects on acid-base and electrolyte status of several crystalloid fluids in 57 stranded juvenile loggerhead turtles. Within a rehabilitation program four different crystalloid fluids were administered (0.9% Na Cl solution; 5% dextrose + 0.9% Na Cl solutions 1:1; 0.9% Na Cl + lactated Ringer's solutions 1:1; lactated Ringer's solution). Crystalloid fluids were intracoelomically administered during three days (20 ml/kg/day). Animals were sampled at three different moments: Upon admission for evaluating the type of acid-base or biochemical disorder, post-fluid therapy treatment for controlling the evolution of the disorder, and post-recovery period for obtaining the baseline values for rehabilitated loggerhead turtles. Each sample was analyzed with a portable electronic blood analyzer for pH, pO2, pCO2, lactate, sodium, potassium, chloride, glucose, and BUN concentration. Admission and post-fluid therapy treatment values were compared with those obtained for each turtle immediately before release. The highest percentage of acid-base recovery and electrolyte balance was observed in turtles treated with mixed saline-lactated Ringer's solution (63.6%), followed by turtles treated with physiological saline solution (55%), lactated Ringer's solution (33.3%), and dextrose-saline solutions (10%). Most turtles treated with lactated Ringer's solution had lower lactate concentrations compared with their initial values; however, 66.6% of turtles treated with lactated Ringer's solution had metabolic alkalosis after therapy. Significant higher concentrations of glucose were detected after saline-dextrose administration compared with all the remaining fluids. This is the first study evaluating the effects of several crystalloid fluids on the acid-base status and plasma biochemical values in stranded loggerhead sea turtles. Reference convalescent venous blood gas, acid-base, and plasma biochemical values, useful for veterinary

  2. Performance Investigation of Automobile Radiator Operated with ZnFe2O4 Nano Fluid based Coolant

    Directory of Open Access Journals (Sweden)

    Tripathi Ajay

    2015-01-01

    Full Text Available The cooling system of an Automobile plays an important role in its performance, consists of two main parts, known as radiator and fan. Improving thermal efficiency of engine leads to increase the engine's performance, decline the fuel consumption and decrease the pollution emissions. Water and ethylene glycol as conventional coolants have been widely used in radiators of an automotive industry for many years. These heat transfer fluids offer low thermal conductivity. With the advancement of nanotechnology, the new generation of heat transfer fluids called, “nanofluids” have been developed and researchers found that these fluids offer higher thermal conductivity compared to that of conventional coolants. This study focused on the preparation of Zinc based nanofluids (ZnFe2O4 using chemical co-precipitation method and its application in an automotive cooling system along with mixture of ethylene glycol and water (50:50. Relevant input data, nanofluids properties and empirical correlations were obtained from literatures to investigate the heat transfer enhancement of an automotive car radiator operated with nano fluid-based coolants. It was observed that, overall heat transfer coefficient and heat transfer rate in engine cooling system increased with the usage of nanofluids (with ethylene glycol the base-fluid compared to ethylene glycol (i.e. base-fluid alone. It is observed that, about 78% of heat transfer enhancement could be achieved with the addition of 1% ZnFe2O4 particles in a base fluid at the Reynolds number of 84.4x103 and 39.5x103 for air and coolant respectively

  3. Evaluation of single and stack membraneless enzymatic fuel cells based on ethanol in simulated body fluids.

    Science.gov (United States)

    Galindo-de-la-Rosa, J; Arjona, N; Moreno-Zuria, A; Ortiz-Ortega, E; Guerra-Balcázar, M; Ledesma-García, J; Arriaga, L G

    2017-06-15

    The purpose of this work is to evaluate single and double-cell membraneless microfluidic fuel cells (MMFCs) that operate in the presence of simulated body fluids SBF, human serum and blood enriched with ethanol as fuels. The study was performed using the alcohol dehydrogenase enzyme immobilised by covalent binding through an array composed of carbon Toray paper as support and a layer of poly(methylene blue)/tetrabutylammonium bromide/Nafion and glutaraldehyde (3D bioanode electrode). The single MMFC was tested in a hybrid microfluidic fuel cell using Pt/C as the cathode. A cell voltage of 1.035V and power density of 3.154mWcm -2 were observed, which is the highest performance reported to date. The stability and durability were tested through chronoamperometry and polarisation/performance curves obtained at different days, which demonstrated a slow decrease in the power density on day 10 (14%) and day 20 (26%). Additionally, the cell was tested for ethanol oxidation in simulated body fluid (SBF) with ionic composition similar to human blood plasma. Those tests resulted in 0.93V of cell voltage and a power density close to 1.237mWcm -2 . The double cell MMFC (Stack) was tested using serum and human blood enriched with ethanol. The stack operated with blood in a serial connection showed an excellent cell performance (0.716mWcm -2 ), demonstrating the feasibility of employing human blood as energy source. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Personal computer (PC) based image processing applied to fluid mechanics research

    Science.gov (United States)

    Cho, Y.-C.; Mclachlan, B. G.

    1987-01-01

    A PC based image processing system was employed to determine the instantaneous velocity field of a two-dimensional unsteady flow. The flow was visualized using a suspension of seeding particles in water, and a laser sheet for illumination. With a finite time exposure, the particle motion was captured on a photograph as a pattern of streaks. The streak pattern was digitized and processsed using various imaging operations, including contrast manipulation, noise cleaning, filtering, statistical differencing, and thresholding. Information concerning the velocity was extracted from the enhanced image by measuring the length and orientation of the individual streaks. The fluid velocities deduced from the randomly distributed particle streaks were interpolated to obtain velocities at uniform grid points. For the interpolation a simple convolution technique with an adaptive Gaussian window was used. The results are compared with a numerical prediction by a Navier-Stokes commputation.

  5. Space nuclear-power reactor design based on combined neutronic and thermal-fluid analyses

    International Nuclear Information System (INIS)

    Koenig, D.R.; Gido, R.G.; Brandon, D.I.

    1985-01-01

    The design and performance analysis of a space nuclear-power system requires sophisticated analytical capabilities such as those developed during the nuclear rocket propulsion (Rover) program. In particular, optimizing the size of a space nuclear reactor for a given power level requires satisfying the conflicting requirements of nuclear criticality and heat removal. The optimization involves the determination of the coolant void (volume) fraction for which the reactor diameter is a minimum and temperature and structural limits are satisfied. A minimum exists because the critical diameter increases with increasing void fraction, whereas the reactor diameter needed to remove a specified power decreases with void fraction. The purpose of this presentation is to describe and demonstrate our analytical capability for the determination of minimum reactor size. The analysis is based on combining neutronic criticality calculations with OPTION-code thermal-fluid calculations

  6. Fracture Propagation, Fluid Flow, and Geomechanics of Water-Based Hydraulic Fracturing in Shale Gas Systems and Electromagnetic Geophysical Monitoring of Fluid Migration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jihoon; Um, Evan; Moridis, George

    2014-12-01

    We investigate fracture propagation induced by hydraulic fracturing with water injection, using numerical simulation. For rigorous, full 3D modeling, we employ a numerical method that can model failure resulting from tensile and shear stresses, dynamic nonlinear permeability, leak-off in all directions, and thermo-poro-mechanical effects with the double porosity approach. Our numerical results indicate that fracture propagation is not the same as propagation of the water front, because fracturing is governed by geomechanics, whereas water saturation is determined by fluid flow. At early times, the water saturation front is almost identical to the fracture tip, suggesting that the fracture is mostly filled with injected water. However, at late times, advance of the water front is retarded compared to fracture propagation, yielding a significant gap between the water front and the fracture top, which is filled with reservoir gas. We also find considerable leak-off of water to the reservoir. The inconsistency between the fracture volume and the volume of injected water cannot properly calculate the fracture length, when it is estimated based on the simple assumption that the fracture is fully saturated with injected water. As an example of flow-geomechanical responses, we identify pressure fluctuation under constant water injection, because hydraulic fracturing is itself a set of many failure processes, in which pressure consistently drops when failure occurs, but fluctuation decreases as the fracture length grows. We also study application of electromagnetic (EM) geophysical methods, because these methods are highly sensitive to changes in porosity and pore-fluid properties due to water injection into gas reservoirs. Employing a 3D finite-element EM geophysical simulator, we evaluate the sensitivity of the crosswell EM method for monitoring fluid movements in shaly reservoirs. For this sensitivity evaluation, reservoir models are generated through the coupled flow

  7. Modeling and test of a kinaesthetic actuator based on MR fluid for haptic applications.

    Science.gov (United States)

    Yang, Tae-Heon; Koo, Jeong-Hoi; Kim, Sang-Youn; Kwon, Dong-Soo

    2017-03-01

    Haptic display units have been widely used for conveying button sensations to users, primarily employing vibrotactile actuators. However, the human feeling for pressing buttons mainly relies on kinaesthetic sensations (rather than vibrotactile sensations), and little studies exist on small-scale kinaesthetic haptic units. Thus, the primary goals of this paper are to design a miniature kinaesthetic actuator based on Magneto-Rheological (MR) fluid that can convey various button-clicking sensations and to experimentally evaluate its haptic performance. The design focuses of the proposed actuator were to produce sufficiently large actuation forces (resistive forces) for human users in a given size constraint and to offer a wide range of actuation forces for conveying vivid haptic sensations to users. To this end, this study first performed a series of parametric studies using mathematical force models for multiple operating modes of MR fluid in conjunction with finite element electromagnetism analysis. After selecting design parameters based on parametric studies, a prototype actuator was constructed, and its performance was evaluated using a dynamic mechanical analyzer. It measured the actuator's resistive force with a varying stroke (pressed depth) up to 1 mm and a varying input current from 0 A to 200 mA. The results show that the proposed actuator creates a wide range of resistive forces from around 2 N (off-state) to over 9.5 N at 200 mA. In order to assess the prototype's performance in the terms of the haptic application prospective, a maximum force rate was calculated to determine just noticeable difference in force changes for the 1 mm stoke of the actuator. The results show that the force rate is sufficient to mimic various levels of button sensations, indicating that the proposed kinaesthetic actuator can offer a wide range of resistive force changes that can be conveyed to human operators.

  8. Water-based inhibitive drilling fluids for oil wells: preliminary study; Fluidos aquosos inibidos para perfuracao de pocos de petroleo: estudo preliminar

    Energy Technology Data Exchange (ETDEWEB)

    Farias, Kassie V.; Amorim, Luciana V.; Silva, Aline R.V.; Ferreira, Heber C. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2008-07-01

    The aim of this work is to do formulations of water-based inhibitive drilling fluids and to evaluate their rheologic, filtration and lubrication properties and the degree of swell of clays. It was studied eight formulations containing the following additives: viscosity, filtered reducer, controlling of pH, hydratable clays inhibitors, anti-foamy, bactericide, lubricant and sealant. The fluids were prepared according to the field practice that consists of adding to water the additives under constant agitation. After 24 h resting, it was carried out a study of the rheologic behavior, in a Fann 35 A viscosimeter, and of the filtration properties in a Fann press-filter and of lubricity in a Ofite Lubricity tester through the determination of the flow curves, apparent and plastic viscosities, yield limit, gel force, filtered volume, filter-cake thickness and lubricity coefficient. It was also been essays to evaluate the capacity of inhibition of clay with the chemical inhibitors isolated and in set. The results had proven that the presence of inhibitor of clay in drilling fluids has great importance and promotes the inhibition of the swell of clay in all concentrations studied and amongst the formulations developed, six had presented performance next to the fluid Standard. (author)

  9. Simulation of solid-liquid flows in a stirred bead mill based on computational fluid dynamics (CFD)

    Science.gov (United States)

    Winardi, S.; Widiyastuti, W.; Septiani, E. L.; Nurtono, T.

    2018-05-01

    The selection of simulation model is an important step in computational fluid dynamics (CFD) to obtain an agreement with experimental work. In addition, computational time and processor speed also influence the performance of the simulation results. Here, we report the simulation of solid-liquid flow in a bead mill using Eulerian model. Multiple Reference Frame (MRF) was also used to model the interaction between moving (shaft and disk) and stationary (chamber exclude shaft and disk) zones. Bead mill dimension was based on the experimental work of Yamada and Sakai (2013). The effect of shaft rotation speed of 1200 and 1800 rpm on the particle distribution and the flow field was discussed. For rotation speed of 1200 rpm, the particles spread evenly throughout the bead mill chamber. On the other hand, for the rotation speed of 1800 rpm, the particles tend to be thrown to the near wall region resulting in the dead zone and found no particle in the center region. The selected model agreed well to the experimental data with average discrepancies less than 10%. Furthermore, the simulation was run without excessive computational cost.

  10. Collaborative Working Architecture for IoT-Based Applications.

    Science.gov (United States)

    Mora, Higinio; Signes-Pont, María Teresa; Gil, David; Johnsson, Magnus

    2018-05-23

    The new sensing applications need enhanced computing capabilities to handle the requirements of complex and huge data processing. The Internet of Things (IoT) concept brings processing and communication features to devices. In addition, the Cloud Computing paradigm provides resources and infrastructures for performing the computations and outsourcing the work from the IoT devices. This scenario opens new opportunities for designing advanced IoT-based applications, however, there is still much research to be done to properly gear all the systems for working together. This work proposes a collaborative model and an architecture to take advantage of the available computing resources. The resulting architecture involves a novel network design with different levels which combines sensing and processing capabilities based on the Mobile Cloud Computing (MCC) paradigm. An experiment is included to demonstrate that this approach can be used in diverse real applications. The results show the flexibility of the architecture to perform complex computational tasks of advanced applications.

  11. Subjective and Objective Work-Based Identity Consequences

    NARCIS (Netherlands)

    Botha, F.C.; Roodt, G.; van de Bunt-Kokhuis, S.G.M.; Jansen, P.G.W.; Roodt, G.

    2015-01-01

    The aim of this chapter is to provide a systematic literature review on the selected consequences of work-based identity (WI). The first section of the chapter includes the following subjective consequences: self-report measures on personal alienation, helping behaviour (H-OCB), burnout (consisting

  12. Comparing international and South African work-based assessment ...

    African Journals Online (AJOL)

    Comparing international and South African work-based assessment of medical interns' practice. ... in the finding that most studies in SA have dealt with the assessment of core procedural skills related to acute clinical care, while the assessment of non-clinical competencies and non-procedural skills was poorly addressed.

  13. Citizen-based Strategies to Improve Community Security: Working ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Citizen-based Strategies to Improve Community Security: Working with Vulnerable Populations to Address Urban Violence in Medellin ... Water Resources Association, in close collaboration with IDRC, is holding a webinar titled “Climate change and adaptive water management: Innovative solutions from the Global South”.

  14. Time-Based Work Interference with Family and Emotional ...

    African Journals Online (AJOL)

    This study investigated the relationship between time-based work interference with family and emotional exhaustion among female teachers. 304 female secondary school teachers between the ages of 26 to 54 years (M= 40.37 and SD =4.09) with educational qualifications ranging from National Certification of Education to ...

  15. Evaluating Deaf Education Web-Based Course Work

    Science.gov (United States)

    Luetke, Barbara

    2009-01-01

    Some U.S. universities use Web-based formats to offer most of the course work required to become a certified teacher of the deaf. Yet little research exists on how students judge the content and delivery of such courses compared to on-campus instruction. Parton (2005) described previous research concerning this topic as descriptive rather than…

  16. Mobile Communication and Work Practices in Knowledge-based Organizations

    Directory of Open Access Journals (Sweden)

    Pertti Hurme

    2005-01-01

    Full Text Available This paper examines the role of mobile communication, mobile tools and work practices in the context of organizations, especially knowledge-based organizations. Today, organizations are highly complex and diverse. Not surprisingly, various solutions to incorporating mobile tools and mobile communication in organizations have been devised. Challenges to technological development and research on mobile communication are presented.

  17. A Society Based on Work. Information Series No. 270.

    Science.gov (United States)

    Carnevale, Anthony Patrick

    American society is based on work. The industrial revolution exposed a growing proportion of the population to unemployment, underemployment, and dislocation. Early theoreticians believed that unemployment was a temporary labor market imbalance that would correct itself with downward wage adjustments. John Maynard Keynes, on the other hand, argued…

  18. WWW-based environments for collaborative group work

    NARCIS (Netherlands)

    Collis, Betty

    1998-01-01

    Since 1994, we have been involved in the design and use of a series of WWW-based environments to support collaborative group work for students in a technical university in The Netherlands. These environments, and the course re-design that accompanies each new environment, began in April 1994 and

  19. Building a Competency-Based Curriculum in Social Work Education

    Science.gov (United States)

    Bracy, Wanda

    2018-01-01

    The focus on competency in social work education makes the development of a competency-based curriculum critical. This article describes an approach to curriculum building taking into account the integration, coherency, and integrity of such a curriculum. A presentation of how performance outcomes are fundamental to the relationship between the…

  20. Validity in work-based assessment: expanding our horizons

    NARCIS (Netherlands)

    Govaerts, M.; Vleuten, C.P.M. van der

    2013-01-01

    CONTEXT: Although work-based assessments (WBA) may come closest to assessing habitual performance, their use for summative purposes is not undisputed. Most criticism of WBA stems from approaches to validity consistent with the quantitative psychometric framework. However, there is increasing

  1. A Working Memory Test Battery: Java-Based Collection of Seven Working Memory Tasks

    Directory of Open Access Journals (Sweden)

    James M Stone

    2015-06-01

    Full Text Available Working memory is a key construct within cognitive science. It is an important theory in its own right, but the influence of working memory is enriched due to the widespread evidence that measures of its capacity are linked to a variety of functions in wider cognition. To facilitate the active research environment into this topic, we describe seven computer-based tasks that provide estimates of short-term and working memory incorporating both visuospatial and verbal material. The memory span tasks provided are; digit span, matrix span, arrow span, reading span, operation span, rotation span, and symmetry span. These tasks are built to be simple to use, flexible to adapt to the specific needs of the research design, and are open source. All files can be downloaded from the project website http://www.cognitivetools.uk and the source code is available via Github.

  2. Simple, stable and reliable modeling of gas properties of organic working fluids in aerodynamic designs of turbomachinery for ORC and VCC

    Science.gov (United States)

    Kawakubo, T.

    2016-05-01

    A simple, stable and reliable modeling of the real gas nature of the working fluid is required for the aerodesigns of the turbine in the Organic Rankine Cycle and of the compressor in the Vapor Compression Cycle. Although many modern Computational Fluid Dynamics tools are capable of incorporating real gas models, simulations with such a gas model tend to be more time-consuming than those with a perfect gas model and even can be unstable due to the simulation near the saturation boundary. Thus a perfect gas approximation is still an attractive option to stably and swiftly conduct a design simulation. In this paper, an effective method of the CFD simulation with a perfect gas approximation is discussed. A method of representing the performance of the centrifugal compressor or the radial-inflow turbine by means of each set of non-dimensional performance parameters and translating the fictitious perfect gas result to the actual real gas performance is presented.

  3. Parametric performance of circumferentially grooved heat pipes with homogeneous and graded-porosity slab wicks at cryogenic temperatures. [methane and ethane working fluids

    Science.gov (United States)

    Groll, M.; Pittman, R. B.; Eninger, J. E.

    1976-01-01

    A recently developed, potentially high-performance nonarterial wick was extensively tested. This slab wick has an axially varying porosity which can be tailored to match the local stress imposed on the wick. The purpose of the tests was to establish the usefulness of the graded-porosity slab wick at cryogenic temperatures between 110 and 260 K, with methane and ethane as working fluids. For comparison, a homogeneous (i.e., uniform porosity) slab wick was also tested. The tests included: maximum heat pipe performance as a function of fluid inventory, maximum performance as a function of operating temperature, maximum performance as a function of evaporator elevation, and influence of slab wick orientation on performance. The experimental data were compared with theoretical predictions obtained with the GRADE computer program.

  4. Size-selective pulmonary dose indices for metal-working fluid aerosols in machining and grinding operations in the automobile manufacturing industry.

    Science.gov (United States)

    Woskie, S R; Smith, T J; Hallock, M F; Hammond, S K; Rosenthal, F; Eisen, E A; Kriebel, D; Greaves, I A

    1994-01-01

    The current metal-working fluid exposures at three locations that manufacture automotive parts were assessed in conjunction with epidemiological studies of the mortality and respiratory morbidity experiences of workers at these plants. A rationale is presented for selecting and characterizing epidemiologic exposure groups in this environment. More than 475 full-shift personal aerosol samples were taken using a two-stage personal cascade impactor with median size cut-offs of 9.8 microns and 3.5 microns, plus a backup filter. For a sample of 403 workers exposed to aerosols of machining or grinding fluids, the mean total exposure was 706 micrograms/m3 (standard error (SE) = 21 micrograms/m3). Among 72 assemblers unexposed to machining fluids, the mean total exposure was 187 +/- 10 (SE) micrograms/m3. An analysis of variance model identified factors significantly associated with exposure level and permitted estimates of exposure for workers in the unsampled machine type/metal-working fluid groups. Comparison of the results obtained from personal impactor samples with predictions from an aerosol-deposition model for the human respiratory tract showed high correlation. However, the amount collected on the impactor stage underestimates extrathoracic deposition and overestimates tracheobronchial and alveolar deposition, as calculated by the deposition model. When both the impactor concentration and the deposition-model concentration were used to estimate cumulative thoracic concentrations for the worklives of a subset of auto workers, there was no significant difference in the rank order of the subjects' cumulative concentration. However, the cumulative impactor concentration values were significantly higher than the cumulative deposition-model concentration values for the subjects.

  5. A Fluid Membrane-Based Soluble Ligand Display System for Live CellAssays

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Jwa-Min; Nair, Pradeep N.; Neve, Richard M.; Gray, Joe W.; Groves, Jay T.

    2005-10-14

    Cell communication modulates numerous biological processes including proliferation, apoptosis, motility, invasion and differentiation. Correspondingly, there has been significant interest in the development of surface display strategies for the presentation of signaling molecules to living cells. This effort has primarily focused on naturally surface-bound ligands, such as extracellular matrix components and cell membranes. Soluble ligands (e.g. growth factors and cytokines) play an important role in intercellular communications, and their display in a surface-bound format would be of great utility in the design of array-based live cell assays. Recently, several cell microarray systems that display cDNA, RNAi, or small molecules in a surface array format were proven to be useful in accelerating high-throughput functional genetic studies and screening therapeutic agents. These surface display methods provide a flexible platform for the systematic, combinatorial investigation of genes and small molecules affecting cellular processes and phenotypes of interest. In an analogous sense, it would be an important advance if one could display soluble signaling ligands in a surface assay format that allows for systematic, patterned presentation of soluble ligands to live cells. Such a technique would make it possible to examine cellular phenotypes of interest in a parallel format with soluble signaling ligands as one of the display parameters. Herein we report a ligand-modified fluid supported lipid bilayer (SLB) assay system that can be used to functionally display soluble ligands to cells in situ (Figure 1A). By displaying soluble ligands on a SLB surface, both solution behavior (the ability to become locally enriched by reaction-diffusion processes) and solid behavior (the ability to control the spatial location of the ligands in an open system) could be combined. The method reported herein benefits from the naturally fluid state of the supported membrane, which allows

  6. Influence of the Applied Working Fluid and the Arrangement of the Steering Edges on Multi-Vane Expander Performance in Micro ORC System

    Directory of Open Access Journals (Sweden)

    Józef Rak

    2018-04-01

    Full Text Available Micro-power domestic organic Rankine cycle (ORC systems are nowadays of great interest. These systems are considered for combined heat and power (CHP generation in domestic and distributed applications. The main issues of ORC systems design is selection of the expander and the working fluid. Thanks to their positive features, multi-vane expanders are especially promising for application in micro-power ORC systems. These expanders are very simple in design, small in dimensions, inexpensive and feature low gas flow capacity and expansion ratio. The application of multi-vane expanders in ORC systems is innovative and currently limited to prototype applications. However, a literature review indicates the growing interest in these machines and the potential for practical implementation. For this reason, it is necessary to conduct detailed studies on the multi-vane expanders operation in ORC systems. In this paper the results of experimental and numerical investigations on the influence of the applied working fluid and the arrangement of the steering edges on multi-vane expander performance in micro ORC system are reported. The experiments were performed using the specially designed lab test-stand, i.e. the domestic ORC system. Numerical simulations were proceeded in ANSYS CFX software (ANSYS, Inc., Canonsburg, PA, USA and were focused on determining the expander performance under various flow conditions of different working fluids. Detailed numerical analysis of the arrangement of the machine steering edges showed existence of optimal mutual position of the inlet and outlet port for which the multi-vane expander achieves maximum internal work and internal efficiency.

  7. Modelling of robotic work cells using agent based-approach

    Science.gov (United States)

    Sękala, A.; Banaś, W.; Gwiazda, A.; Monica, Z.; Kost, G.; Hryniewicz, P.

    2016-08-01

    In the case of modern manufacturing systems the requirements, both according the scope and according characteristics of technical procedures are dynamically changing. This results in production system organization inability to keep up with changes in a market demand. Accordingly, there is a need for new design methods, characterized, on the one hand with a high efficiency and on the other with the adequate level of the generated organizational solutions. One of the tools that could be used for this purpose is the concept of agent systems. These systems are the tools of artificial intelligence. They allow assigning to agents the proper domains of procedures and knowledge so that they represent in a self-organizing system of an agent environment, components of a real system. The agent-based system for modelling robotic work cell should be designed taking into consideration many limitations considered with the characteristic of this production unit. It is possible to distinguish some grouped of structural components that constitute such a system. This confirms the structural complexity of a work cell as a specific production system. So it is necessary to develop agents depicting various aspects of the work cell structure. The main groups of agents that are used to model a robotic work cell should at least include next pattern representatives: machine tool agents, auxiliary equipment agents, robots agents, transport equipment agents, organizational agents as well as data and knowledge bases agents. In this way it is possible to create the holarchy of the agent-based system.

  8. Field—Based Supercritical Fluid Extraction of Hydrocarbons at Industrially Contaminated Sites

    Directory of Open Access Journals (Sweden)

    Peggy Rigou

    2002-01-01

    Full Text Available Examination of organic pollutants in groundwaters should also consider the source of the pollution, which is often a solid matrix such as soil, landfill waste, or sediment. This premise should be viewed alongside the growing trend towards field-based characterisation of contaminated sites for reasons of speed and cost. Field-based methods for the extraction of organic compounds from solid samples are generally cumbersome, time consuming, or inefficient. This paper describes the development of a field-based supercritical fluid extraction (SFE system for the recovery of organic contaminants (benzene, toluene, ethylbenzene, and xylene and polynuclear aromatic hydrocarbons from soils. A simple, compact, and robust SFE system has been constructed and was found to offer the same extraction efficiency as a well-established laboratory SFE system. Extraction optimisation was statistically evaluated using a factorial analysis procedure. Under optimised conditions, the device yielded recovery efficiencies of >70% with RSD values of 4% against the standard EPA Soxhlet method, compared with a mean recovery efficiency of 48% for a commercially available field-extraction kit. The device will next be evaluated with real samples prior to field deployment.

  9. Liquid-Based Cytology of the Cerebrospinal Fluid in a Case of Cryptococcal Meningitis

    Directory of Open Access Journals (Sweden)

    Jiwoon Choi

    2018-01-01

    Full Text Available Cryptococcus neoformans is the most common microorganism found in cerebrospinal fluid (CSF cytology and causes life-threatening infections in immunocompromised hosts. Although its cytomorphologic features in conventional smear cytology have been well described, those in liquid-based cytology have rarely been. A 73-year-old woman with diffuse large B-cell lymphoma presented with mental confusion and a spiking fever. To rule out infectious conditions, CSF examination was performed. A cytology slide that was prepared using the ThinPrep method showed numerous spherical yeast-form organisms with diameters of 4–11 μm and thick capsules. Occasional asymmetrical, narrow-based budding but no true hyphae or pseudohyphae were observed. Gomori methenamine silver staining was positive. Cryptococcosis was confirmed in blood and CSF through the cryptococcal antigen test and culture. Liquid-based cytology allows for a clean background and additional slides for ancillary testing, facilitating the detection of microorganisms in CSF specimens, particularly when the number of organisms is small.

  10. Liquid-Based Cytology of the Cerebrospinal Fluid in a Case of Cryptococcal Meningitis.

    Science.gov (United States)

    Choi, Jiwoon; Kim, Se Hoon

    2018-01-01

    Cryptococcus neoformans is the most common microorganism found in cerebrospinal fluid (CSF) cytology and causes life-threatening infections in immunocompromised hosts. Although its cytomorphologic features in conventional smear cytology have been well described, those in liquid-based cytology have rarely been. A 73-year-old woman with diffuse large B-cell lymphoma presented with mental confusion and a spiking fever. To rule out infectious conditions, CSF examination was performed. A cytology slide that was prepared using the ThinPrep method showed numerous spherical yeast-form organisms with diameters of 4-11 μm and thick capsules. Occasional asymmetrical, narrow-based budding but no true hyphae or pseudohyphae were observed. Gomori methenamine silver staining was positive. Cryptococcosis was confirmed in blood and CSF through the cryptococcal antigen test and culture. Liquid-based cytology allows for a clean background and additional slides for ancillary testing, facilitating the detection of microorganisms in CSF specimens, particularly when the number of organisms is small.

  11. The acid-base effects of continuous hemofiltration with lactate or bicarbonate buffered replacement fluids.

    Science.gov (United States)

    Tan, H K; Uchino, S; Bellomo, R

    2003-06-01

    To evaluate, quantify and compare the effects of continuous veno-venous hemofiltration (CVVH) with lactate or bicarbonate-buffered replacement fluids on acid-base balance. Randomized double crossover study. Intensive Care Unit of Tertiary Medical Center. Eight patients with severe acute renal failure. Random allocation to either 2 hours of isovolemic lactate-buffered (treatment A) CVVH or 2 hours of bicarbonate-buffered (treatment B) CVVH with cross over and with same procedure repeated the following day (double cross over). Timed collections of arterial blood and ultrafiltrate (UF), measurement of blood and UF gases and lactate concentrations and calculation of buffer-base mass balance. At baseline, both groups of patients had a similar, slight metabolic alkalosis (pH: 7.45 vs. 7.45; BE 3.9 mEq/L for treatment A and 4.0 for treatment B) and a serum bicarbonate of 28.1 mmol/L for treatment A vs. 28.3 mmol/L for treatment B; all NS. This alkalosis was present despite slight hyperlactatemia in both groups (A: 2.4 mmol/L vs. B 2.8 mmol/; NS). Within 60 minutes of treatment, however, treatment A led to a significantly higher lactate concentration (3.9 vs 2.5 mmol/L; p = 0.0011), a significantly lower BE (2.3 vs 4.1 mEq/L; p = 0.0019) and a significantly lower bicarbonate concentration (26.7 vs. 28.3 mmol/L; p = 0.0038) in the presence of an unchanged PaCO2. These differences persisted during the study period. The UF of patients receiving treatment A contained more lactate (10.2 vs 2.9 mmol/L; p buffer-base balance of +20.4 mEq/h compared to -2.6 mEq/h for treatment B; p buffered replacement fluids induces iatrogenic hyperlactatemia. Such hyperlactatemia is associated with an acidifying effect despite a positive buffer-base balance.

  12. Hydromagnetic slip flow of water based nano-fluids past a wedge with convective surface in the presence of heat generation (or) absorption

    International Nuclear Information System (INIS)

    Rahman, M.M.; Al-Lawatia, M.A.; Eltayeb, I.A.; Al-Salti, N.

    2012-01-01

    Heat transfer characteristics of a two-dimensional steady hydromagnetic slip flow of water based nano-fluids (TiO 2 -water, Al 2 O 3 -water, and Cu-water) over a wedge with convective surface taking into account the effects of heat generation (or absorption) has been investigated numerically. The local similarity solutions are obtained by using very robust computer algebra software MATLAB and presented graphically as well as in a tabular form. The results show that nano-fluid velocity is lower than the velocity of the base fluid and the existence of the nano-fluid leads to the thinning of the hydrodynamic boundary layer. The rate of shear stress is significantly influenced by the surface convection parameter and the slip parameter. It is higher for nano-fluids than the base fluid. The results also show that within the boundary layer the temperature of the nano-fluid is higher than the temperature of the base fluid. The rate of heat transfer is found to increase with the increase of the surface convection and the slip parameters. Addition of nano-particles to the base fluid induces the rate of heat transfer. The rate of heat transfer in the Cu-water nano-fluid is found to be higher than the rate of heat transfer in the TiO 2 -water and Al 2 O 3 -water nano-fluids. (authors)

  13. Investigation and optimization of performance of nano-scale Stirling refrigerator using working fluid as Maxwell-Boltzmann gases

    Science.gov (United States)

    Ahmadi, Mohammad H.; Amin Nabakhteh, Mohammad; Ahmadi, Mohammad-Ali; Pourfayaz, Fathollah; Bidi, Mokhtar

    2017-10-01

    The motivation behind this work is to explore a nanoscale irreversible Stirling refrigerator with respect to size impacts and shows two novel thermo-ecological criteria. Two distinct strategies were suggested in the optimization process and the consequences of every strategy were examined independently. In the primary strategy, with the purpose of maximizing the energetic sustainability index and modified the ecological coefficient of performance (MECOP) and minimizing the dimensionless Ecological function, a multi-objective optimization algorithm (MOEA) was used. In the second strategy, with the purpose of maximizing the ECOP and MECOP and minimizing the dimensionless Ecological function, a MOEA was used. To conclude the final solution from each strategy, three proficient decision makers were utilized. Additionally, to quantify the deviation of the results gained from each decision makers, two different statistical error indexes were employed. Finally, based on the comparison between the results achieved from proposed scenarios reveals that by maximizing the MECOP the maximum values of ESI, ECOP, and a minimum of ecfare achieved.

  14. Strengthening health workforce capacity through work-based training

    Directory of Open Access Journals (Sweden)

    Matovu Joseph KB

    2013-01-01

    Full Text Available Abstract Background Although much attention has been given to increasing the number of health workers, less focus has been directed at developing models of training that address real-life workplace needs. Makerere University School of Public Health (MakSPH with funding support from the Centers for Disease Control and Prevention (CDC developed an eight-month modular, in-service work-based training program aimed at strengthening the capacity for monitoring and evaluation (M&E and continuous quality improvement (CQI in health service delivery. Methods This capacity building program, initiated in 2008, is offered to in-service health professionals working in Uganda. The purpose of the training is to strengthen the capacity to provide quality health services through hands-on training that allows for skills building with minimum work disruptions while encouraging greater involvement of other institutional staff to enhance continuity and sustainability. The hands-on training uses practical gaps and challenges at the workplace through a highly participatory process. Trainees work with other staff to design and implement ‘projects’ meant to address work-related priority problems, working closely with mentors. Trainees’ knowledge and skills are enhanced through short courses offered at specific intervals throughout the course. Results Overall, 143 trainees were admitted between 2008 and 2011. Of these, 120 (84% from 66 institutions completed the training successfully. Of the trainees, 37% were Social Scientists, 34% were Medical/Nursing/Clinical Officers, 5.8% were Statisticians, while 23% belonged to other professions. Majority of the trainees (80% were employed by Non-Government Organizations while 20% worked with the public health sector. Trainees implemented 66 projects which addressed issues such as improving access to health care services; reducing waiting time for patients; strengthening M&E systems; and improving data collection and

  15. Analysis of the flow dynamics characteristics of an axial piston pump based on the computational fluid dynamics method

    Directory of Open Access Journals (Sweden)

    Bin Zhang

    2017-01-01

    Full Text Available To improve its working performance, the flow ripple characteristics of an axial piston pump were investigated with software which uses computational fluid dynamics (CFD technology. The simulation accuracy was significantly optimized through the use of the improved compressible fluid model. Flow conditions of the pump were tested using a pump flow ripple test rig, and the simulation results of the CFD model showed good agreement with the experimental data. Additionally, the composition of the flow ripple was analyzed using the improved CFD model, and the results showed that the compression ripple makes up 88% of the flow ripple. The flow dynamics of the piston pump is mainly caused by the pressure difference between the intake and discharge ports of the valve plates and the fluid oil compressibility.

  16. Damage evaluation on oil-based drill-in fluids for ultra-deep fractured tight sandstone gas reservoirs

    Directory of Open Access Journals (Sweden)

    Jinzhi Zhu

    2017-07-01

    Full Text Available In order to explore the damage mechanisms and improve the method to evaluate and optimize the performance of formation damage control of oil-based drill-in fluids, this paper took an ultra-deep fractured tight gas reservoir in piedmont configuration, located in the Cretaceous Bashijiqike Fm of the Tarim Basin, as an example. First, evaluation experiments were conducted on the filtrate invasion, the dynamic damage of oil-based drill-in fluids and the loading capacity of filter cakes. Meanwhile, the evaluating methods were optimized for the formation damage control effect of oil-based drill-in fluids in laboratory: pre-processing drill-in fluids before grading analysis; using the dynamic damage method to simulate the damage process for evaluating the percentage of regained permeability; and evaluating the loading capacity of filter cakes. The experimental results show that (1 oil phase trapping damage and solid phase invasion are the main formation damage types; (2 the damage degree of filtrate is the strongest on the matrix; and (3 the dynamic damage degree of oil-based drill-in fluids reaches medium strong to strong on fractures and filter cakes show a good sealing capacity for the fractures less than 100 μm. In conclusion, the filter cakes' loading capacity should be first guaranteed, and both percentage of regained permeability and liquid trapping damage degree should be both considered in the oil-based drill-in fluids prepared for those ultra-deep fractured tight sandstone gas reservoirs.

  17. Goal-Directed Fluid Resuscitation Protocol Based on Arterial Waveform Analysis of Major Burn Patients in a Mass Burn Casualty.

    Science.gov (United States)

    Chiao, Hao-Yu; Chou, Chang-Yi; Tzeng, Yuan-Sheng; Wang, Chih-Hsin; Chen, Shyi-Gen; Dai, Niann-Tzyy

    2018-02-01

    Adequate fluid titration during the initial resuscitation period of major burn patients is crucial. This study aimed to evaluate the feasibility and efficacy of a goal-directed fluid resuscitation protocol that used hourly urine output plus the arterial waveform analysis FloTrac (Edwards LifeSciences, Irvine, Calif) system for major burns to avoid fluid overload. We conducted a retrospective cohort study of 43 major burn patients at the Tri-Service General Hospital after the Formosa Fun Coast Dust Explosion on June 27, 2015. Because of the limited capacity of intensive care units (ICUs), 23 intubated patients were transferred from the burn wards or emergency department to the ICU within 24 hours. Fluid administration was adjusted to achieve a urine output of 30 to 50 mL/h, cardiac index greater than 2.5 L/min/m, and stroke volume variation (SVV) less than 12%. The hourly crystalloid fluid infusion rate was titrated based on SVV and hourly urine output. Of the 23 critically burned patients admitted to the ICU, 13 patients who followed the goal-directed fluid resuscitation protocol within 12 hours postburn were included in the analysis. The mean age (years) was 21.8, and the mean total body surface area (TBSA) burned (%) was 68.0. The mean Revised Baux score was 106.8. All patients sustained inhalation injury. The fluid volumes administered to patients in the first 24 hours and the second 24 hours (mL/kg/% total body surface area) were 3.62 ± 1.23 and 2.89 ± 0.79, respectively. The urine outputs in the first 24 hours and the second 24 hours (mL/kg/h) were 1.13 ± 0.66 and 1.53 ± 0.87, respectively. All patients achieved the established goals within 32 hours postburn. In-hospital mortality rate was 0%. The SVV-based goal-directed fluid resuscitation protocol leads to less unnecessary fluid administration during the early resuscitation phase. Clinicians can efficaciously manage the dynamic body fluid changes in major burn patients under the guidance of the protocol.

  18. Mass spectrometry-based cDNA profiling as a potential tool for human body fluid identification.

    Science.gov (United States)

    Donfack, Joseph; Wiley, Anissa

    2015-05-01

    Several mRNA markers have been exhaustively evaluated for the identification of human venous blood, saliva, and semen in forensic genetics. As new candidate human body fluid specific markers are discovered, evaluated, and reported in the scientific literature, there is an increasing trend toward determining the ideal markers for cDNA profiling of body fluids of forensic interest. However, it has not been determined which molecular genetics-based technique(s) should be utilized to assess the performance of these markers. In recent years, only a few confirmatory, mRNA/cDNA-based methods have been evaluated for applications in body fluid identification. The most frequently described methods tested to date include quantitative polymerase chain reaction (qPCR) and capillary electrophoresis (CE). However these methods, in particular qPCR, often favor narrow multiplex PCR due to the availability of a limited number of fluorescent dyes/tags. In an attempt to address this technological constraint, this study explored matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) for human body fluid identification via cDNA profiling of venous blood, saliva, and semen. Using cDNA samples at 20pg input phosphoglycerate kinase 1 (PGK1) amounts, body fluid specific markers for the candidate genes were amplified in their corresponding body fluid (i.e., venous blood, saliva, or semen) and absent in the remaining two (100% specificity). The results of this study provide an initial indication that MALDI-TOF MS is a potential fluorescent dye-free alternative method for body fluid identification in forensic casework. However, the inherent issues of low amounts of mRNA, and the damage caused to mRNA by environmental exposures, extraction processes, and storage conditions are important factors that significantly hinder the implementation of cDNA profiling into forensic casework. Published by Elsevier Ireland Ltd.

  19. Women working at university restaurants: life and work conditions and gender-based violence

    Directory of Open Access Journals (Sweden)

    Kelly Cristina Maxima Pereira Venancio

    2013-10-01

    Full Text Available This is an exploratory and descriptive study with a quantitative approach that aimed to understand the social production and reproduction processes of women working at university restaurants and the occurrence and the magnitude of gender-based violence committed against them by their intimate partners. The data were collected through semi-structured interviews. The analysis categories used were social production and reproduction, gender and gender-based violence. The interviewees held a subordinate social position during the productive and reproductive periods of their lives. Approximately 70% reported having experienced gender-based violence from an intimate partner (66% psychological violence, 36.3% physical violence and 28.6% sexual violence. Most of the health problems resulting from violence were related to mental health. The results indicate that the situation requires immediate interventions, mostly guided by the instrumentalization of these women and the support by the state and the university as appropriate to address violence.

  20. Recent advances in quantitative analysis of fluid interfaces in multiphase fluid flow measured by synchrotron-based x-ray microtomography

    Science.gov (United States)

    Schlueter, S.; Sheppard, A.; Wildenschild, D.

    2013-12-01

    Imaging of fluid interfaces in three-dimensional porous media via x-ray microtomography is an efficient means to test thermodynamically derived predictions on the relationship between capillary pressure, fluid saturation and specific interfacial area (Pc-Sw-Anw) in partially saturated porous media. Various experimental studies exist to date that validate the uniqueness of the Pc-Sw-Anw relationship under static conditions and with current technological progress direct imaging of moving interfaces under dynamic conditions is also becoming available. Image acquisition and subsequent image processing currently involves many steps each prone to operator bias, like merging different scans of the same sample obtained at different beam energies into a single image or the generation of isosurfaces from the segmented multiphase image on which the interface properties are usually calculated. We demonstrate that with recent advancements in (i) image enhancement methods, (ii) multiphase segmentation methods and (iii) methods of structural analysis we can considerably decrease the time and cost of image acquisition and the uncertainty associated with the measurement of interfacial properties. In particular, we highlight three notorious problems in multiphase image processing and provide efficient solutions for each: (i) Due to noise, partial volume effects, and imbalanced volume fractions, automated histogram-based threshold detection methods frequently fail. However, these impairments can be mitigated with modern denoising methods, special treatment of gray value edges and adaptive histogram equilization, such that most of the standard methods for threshold detection (Otsu, fuzzy c-means, minimum error, maximum entropy) coincide at the same set of values. (ii) Partial volume effects due to blur may produce apparent water films around solid surfaces that alter the specific fluid-fluid interfacial area (Anw) considerably. In a synthetic test image some local segmentation methods

  1. WORK BASED HIGHER LEARNING FOR THE DANISH TOURISM SECTOR

    DEFF Research Database (Denmark)

    Lindegaard, Klaus; Voergård-Olesen, Rikke Karen

    2012-01-01

    programs for tourism. This is the basis for reflexive analysis of how demand and supply for higher education can be aligned for the sector. The research focuses on the role of WBL as a way to meet the needs for flexible competence building. Special emphasis is put on innovation and environmental management......The paper reports on an investigation of the business needs for work based higher learning in the Danish tourism sector and the match with the supply of higher education, emphasizing opportunities and barriers for work based learning (WBL) in the Danish University System. The Danish tourism sector...... need for development through further and higher education of employees is widely recognized, while Danish higher education is challenged to develop a more demand-led approach. The research done consists of completed empirical studies and literature review on Danish tourism and Danish higher education...

  2. Rapid and inexpensive body fluid identification by RNA profiling-based multiplex High Resolution Melt (HRM) analysis.

    Science.gov (United States)

    Hanson, Erin K; Ballantyne, Jack

    2013-01-01

    Positive identification of the nature of biological material present on evidentiary items can be crucial for understanding the circumstances surrounding a crime. However, traditional protein-based methods do not permit the identification of all body fluids and tissues, and thus molecular based strategies for the conclusive identification of all forensically relevant biological fluids and tissues need to be developed. Messenger RNA (mRNA) profiling is an example of such a molecular-based approach. Current mRNA body fluid identification assays involve capillary electrophoresis (CE) or quantitative RT-PCR (qRT-PCR) platforms, each with its own limitations. Both platforms require the use of expensive fluorescently labeled primers or probes. CE-based assays require separate amplification and detection steps thus increasing the analysis time. For qRT-PCR assays, only 3-4 markers can be included in a single reaction since each requires a different fluorescent dye. To simplify mRNA profiling assays, and reduce the time and cost of analysis, we have developed single- and multiplex body fluid High Resolution Melt (HRM) assays for the identification of common forensically relevant biological fluids and tissues. The incorporated biomarkers include IL19 (vaginal secretions), IL1F7 (skin), ALAS2 (blood), MMP10 (menstrual blood), HTN3 (saliva) and TGM4 (semen).  The HRM assays require only unlabeled PCR primers and a single saturating intercalating fluorescent dye (Eva Green). Each body-fluid-specific marker can easily be identified by the presence of a distinct melt peak. Usually, HRM assays are used to detect variants or isoforms for a single gene target. However, we have uniquely developed duplex and triplex HRM assays to permit the simultaneous detection of multiple targets per reaction. Here we describe the development and initial performance evaluation of the developed HRM assays. The results demonstrate the potential use of HRM assays for rapid, and relatively inexpensive

  3. A Deep Learning based Approach to Reduced Order Modeling of Fluids using LSTM Neural Networks

    Science.gov (United States)

    Mohan, Arvind; Gaitonde, Datta

    2017-11-01

    Reduced Order Modeling (ROM) can be used as surrogates to prohibitively expensive simulations to model flow behavior for long time periods. ROM is predicated on extracting dominant spatio-temporal features of the flow from CFD or experimental datasets. We explore ROM development with a deep learning approach, which comprises of learning functional relationships between different variables in large datasets for predictive modeling. Although deep learning and related artificial intelligence based predictive modeling techniques have shown varied success in other fields, such approaches are in their initial stages of application to fluid dynamics. Here, we explore the application of the Long Short Term Memory (LSTM) neural network to sequential data, specifically to predict the time coefficients of Proper Orthogonal Decomposition (POD) modes of the flow for future timesteps, by training it on data at previous timesteps. The approach is demonstrated by constructing ROMs of several canonical flows. Additionally, we show that statistical estimates of stationarity in the training data can indicate a priori how amenable a given flow-field is to this approach. Finally, the potential and limitations of deep learning based ROM approaches will be elucidated and further developments discussed.

  4. An adjoint-based framework for maximizing mixing in binary fluids

    Science.gov (United States)

    Eggl, Maximilian; Schmid, Peter

    2017-11-01

    Mixing in the inertial, but laminar parameter regime is a common application in a wide range of industries. Enhancing the efficiency of mixing processes thus has a fundamental effect on product quality, material homogeneity and, last but not least, production costs. In this project, we address mixing efficiency in the above mentioned regime (Reynolds number Re = 1000 , Peclet number Pe = 1000) by developing and demonstrating an algorithm based on nonlinear adjoint looping that minimizes the variance of a passive scalar field which models our binary Newtonian fluids. The numerical method is based on the FLUSI code (Engels et al. 2016), a Fourier pseudo-spectral code, which we modified and augmented by scalar transport and adjoint equations. Mixing is accomplished by moving stirrers which are numerically modeled using a penalization approach. In our two-dimensional simulations we consider rotating circular and elliptic stirrers and extract optimal mixing strategies from the iterative scheme. The case of optimizing shape and rotational speed of the stirrers will be demonstrated.

  5. A Matlab user interface for the statistically assisted fluid registration algorithm and tensor-based morphometry

    Science.gov (United States)

    Yepes-Calderon, Fernando; Brun, Caroline; Sant, Nishita; Thompson, Paul; Lepore, Natasha

    2015-01-01

    Tensor-Based Morphometry (TBM) is an increasingly popular method for group analysis of brain MRI data. The main steps in the analysis consist of a nonlinear registration to align each individual scan to a common space, and a subsequent statistical analysis to determine morphometric differences, or difference in fiber structure between groups. Recently, we implemented the Statistically-Assisted Fluid Registration Algorithm or SAFIRA,1 which is designed for tracking morphometric differences among populations. To this end, SAFIRA allows the inclusion of statistical priors extracted from the populations being studied as regularizers in the registration. This flexibility and degree of sophistication limit the tool to expert use, even more so considering that SAFIRA was initially implemented in command line mode. Here, we introduce a new, intuitive, easy to use, Matlab-based graphical user interface for SAFIRA's multivariate TBM. The interface also generates different choices for the TBM statistics, including both the traditional univariate statistics on the Jacobian matrix, and comparison of the full deformation tensors.2 This software will be freely disseminated to the neuroimaging research community.

  6. Cardiac output-based fluid optimization for kidney transplant recipients: a proof-of-concept trial.

    Science.gov (United States)

    Corbella, Davide; Toppin, Patrick Jason; Ghanekar, Anand; Ayach, Nour; Schiff, Jeffery; Van Rensburg, Adrian; McCluskey, Stuart A

    2018-04-10

    Intravenous fluid management for deceased donor kidney transplantation is an important, modifiable risk factor for delayed graft function (DGF). The primary objective of this study was to determine if goal-directed fluid therapy using esophageal Doppler monitoring (EDM) to optimize stroke volume (SV) would alter the amount of fluid given. This randomized, proof-of-concept trial enrolled 50 deceased donor renal transplant recipients. Data collected included patient characteristics, fluid administration, hemodynamics, and complications. The EDM was used to optimize SV in the EDM group. In the control group, fluid management followed the current standard of practice. The groups were compared for the primary outcome of total intraoperative fluid administered. There was no difference in the mean (standard deviation) volume of intraoperative fluid administered to the 24 control and 26 EDM patients [2,307 (750) mL vs 2,675 (842) mL, respectively; mean difference, 368 mL; 95% confidence interval (CI), - 87 to + 823; P = 0.11]. The incidence of complications in the control and EDM groups was similar (15/24 vs 17/26, respectively; P = 0.99), as was the incidence of delayed graft failure (8/24 vs 11/26, respectively; P = 0.36). Goal-directed fluid therapy did not alter the volume of fluid administered or the incidence of complications. This proof-of-concept trial provides needed data for conducting a larger trial to determine the influence of fluid therapy on the incidence in DGF in deceased donor kidney transplantation. www.clinicaltrials.gov (NCT02512731). Registered 31 July 2015.

  7. Baseline System Costs for 50.0 MW Enhanced Geothermal System -- A Function of: Working Fluid, Technology, and Location, Location, Location

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, Paul [Gas Equipment Engineering Corp., Milford, CT (United States); Selman, Nancy [Gas Equipment Engineering Corp., Milford, CT (United States); Volpe, Anthony Della [Gas Equipment Engineering Corp., Milford, CT (United States); Moss, Deborah [Gas Equipment Engineering Corp., Milford, CT (United States); Mobley, Rick [Plasma Energy Services, LLC, Putnam, CT (United States); Dickey, Halley [Turbine Air Systems, Houston, TX (United States); Unruh, Jeffery [Fugro NV/Wm. Lettis & Associates, Houston, TX (United States); Hitchcock, Chris [Fugro NV/Wm. Lettis & Associates, Houston, TX (United States); Tanguay, Jasmine [Conservation Law Foundation/CLF Ventures, Boston, MA (United States); Larsen, Walker [Conservation Law Foundation/CLF Ventures, Boston, MA (United States); Sanyal, Sabir [GeothermEx, Inc., San Pablo, CA (United States); Butler, Steven [GeothermEx, Inc., San Pablo, CA (United States); Stacey, Robert [GeothermEx, Inc., San Pablo, CA (United States); Robertson-Tait, Ann [GeothermEx, Inc., San Pablo, CA (United States); Pruess, Karsten [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gutoski, Greg [Fairbanks Morse Engines (FME), Beloit, WI (United States); Fay, Jamie M. [Fort Point Associates, Boston, MA (United States); Stitzer, John T. [Fort Point Associates, Boston, MA (United States); Oglesby, Ken [Impact Technologies LLC, Tulsa, OK (United States)

    2012-04-30

    Substantial unexploited opportunity exists for the US, and the world, in Enhanced Geothermal Systems (EGS). As a result of US DOE investment, new drilling technology, new power generation equipment and cycles enable meaningful power production, in a compact and modular fashion; at lower and lower top side EGS working fluid temperatures and in a broader range of geologies and geographies. This cost analysis effort supports the expansion of Enhanced Geothermal Systems (EGS), furthering DOE strategic themes of energy security and sub goal of energy diversity; reducing the Nation's dependence on foreign oil while improving the environment.

  8. Unitary or Non-Unitary Nature of Working Memory? Evidence from Its Relation to General Fluid and Crystallized Intelligence

    Science.gov (United States)

    Dang, Cai-Ping; Braeken, Johan; Ferrer, Emilio; Liu, Chang

    2012-01-01

    This study explored the controversy surrounding working memory: whether it is a unitary system providing general purpose resources or a more differentiated system with domain-specific sub-components. A total of 348 participants completed a set of 6 working memory tasks that systematically varied in storage target contents and type of information…

  9. The baseline fluid intelligence modulated the transfer effect from working memory to fluid intelligence%个体差异对工作记忆训练迁移效果的调节

    Institute of Scientific and Technical Information of China (English)

    朱祖德; 段懿行; 王穗苹

    2017-01-01

    While some previous studies have found significant transfer effect from working memory to fluid intelligence, other studies have failed. The discrepancy may due to individual difference. One type of individual differences is the working memory training improvement. It was found that, transfer effect was found only in subjects who showed significant training improvement. Another type of individual differences is the cognitive ability at baseline, such as baseline fluid intelligence. It remains unclear how such individual differences modulate transfer effect in working memory training. Specifically, the aim of the present study was to investigate how the individual fluid intelligence at baseline modulates the working memory transfer effect. In total, 40 college students were recruited and randomly assigned into active control group (N = 19, 8 males/ 11 females) and training group (N = 21, 9 males /12 females). The training group was asked to complete a dual n-back task. The participants were asked to perform the training 25 minutes a day, 5 days per week in four weeks. The dual n-back task was computerized, in which participants were required to determine if the stimulus position and voice in the current trial were the same as that in the previous n-1 trial. The n was adaptively changed according to the participants' performances. Meanwhile, the active control group received a scientific knowledge reading training. To make sure the participants' engaged in the task, the reading material was different for each time. The training time setting in the active control group was the same as that in the training group. All participants were tested by the Raven's Standard Progressive Matrices (RSPM) before and after the training. In order to avoid the impact of repeated measures, the RSPM were divided into two parallel tests and were counterbalanced across groups and test sessions. The training group showed significant improvement in the dual n-back task, with an average

  10. Computational Fluid Dynamics in Ventilation

    DEFF Research Database (Denmark)

    Nielsen, Peter V.; Allard, Francis; Awbi, Hazim B.

    2008-01-01

    Computational Fluid Dynamics in Ventilation Design is a new title in the is a new title in the REHVA guidebook series. The guidebook is written for people who need to use and discuss results based on CFD predictions, and it gives insight into the subject for those who are not used to work with CFD...

  11. Effect of Nitric Acid on the Low Fluorescing Performance of Drilling Fluid Lubricant Based Animal and Vegetable Oils

    Directory of Open Access Journals (Sweden)

    Feng-shan Zhou

    2013-01-01

    Full Text Available After synthesis of mixed fatty acid triethanolamine ester surfactant based on animal and vegetable mixed oils, the reaction solution was added into 4% (wt/wt liquid nitric acid or 9% (wt/wt solid nitric acid as eliminating fluorescent agent continuing to react from 1 to 2 hours. The low fluorescence lubricant named E167 for drilling fluid was prepared, in which maximum fluorescence intensity (Fmax was less than 10 in three-dimensional fluorescence spectra of excitation wavelength range. When the E167 was added into fresh water based drilling fluid at the dosage of 0.5% (wt/wt, the sticking coefficient reduced rate (ΔKf is 78% and the extreme pressure (E-P friction coefficient reduced rate (Δf is 79%. In the case of 4% brine mud with 0.5% (wt/wt E167 in it, the ΔKf and Δf are 75% and 62%, respectively. After the hot rolling ageing test 180°C × 16 h with the E167 was added into fresh water based drilling fluid at the dosage of 1% (wt/wt, the ΔKf and Δf are greater than 70%, which shows a much better lubrication properties of strong resistance to high temperature. The fresh water based drilling fluid which contains 1% (wt/wt E167 is almost nonfoaming even after hot rolling ageing 120°C × 16 h.

  12. Meningitis caused by Enterococcus casseliflavus with refractory cerebrospinai fluid leakage following endoscopic endonasal removal of skull base chondrosarcoma

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    To the Editor:Meningitis caused by Enterococcus casseliflavus (E.casseliflavus) is extremely rare.Here we report an unusual case of meningitis caused by E.casseliflavus coexisting with refractory cerebrospinal fluid (CSF) leakage following endoscopic endonasal resection of skull base chondrosarcoma.

  13. Structure and acidity of individual Fluid Catalytic Cracking catalyst particles studied by synchrotron-based infrared micro-spectroscopy

    NARCIS (Netherlands)

    Buurmans, I.L.C.; Soulimani, F.; Ruiz Martinez, J.; van der Bij, H.E.; Weckhuysen, B.M.

    2013-01-01

    A synchrotron-based infrared micro-spectroscopy study has been conducted to investigate the structure as well as the Brønsted and Lewis acidity of Fluid Catalytic Cracking (FCC) catalyst particles at the individual particle level. Both fresh and laboratory-deactivated catalyst particles have been

  14. Droplet generating device for droplet-based μTAS using electro-conjugate fluid

    Science.gov (United States)

    Iijima, Y.; Takemura, K.; Edamura, K.

    2017-05-01

    Droplet-based μTAS, which carries out biochemical inspection and synthesis by handling samples as droplets on a single chip, has been attracting attentions in recent years. Although miniaturization of a chip is progressed, there are some problems in miniaturization of a whole system because of the necessity to connect syringe pumps to the chip. Thus, this study aims to realize a novel droplets generating device for droplet-based μTAS using electro-conjugate fluid (ECF). The ECF is a dielectric liquid generating a powerful flow when subjected to high DC voltage. The ECF flow generation allows us to realize a tiny hydraulic power source. Using the ECF flow, we can develop a droplet generating device for droplet-based μTAS by placing minute electrode pairs in flow channels. The device contains two channels filled with the ECF, which are dispersed and continuous phases meeting at a T-junction. When a sample in the dispersed phase is injected by the ECF flow to the continuous phase at T-junction, droplets are generated by shearing force between the two phases. We conducted droplet generating experiment and confirmed that droplets are successfully generated when the flow rate of the continuous phase is between 90 and 360 mm3 s-1, and the flow rate of the dispersed phase is between 10 and 40 mm3 s-1. We also confirmed that the droplet diameter and the droplet production rate are controllable by tuning the applied voltage to the electrode pairs.

  15. Performance Comparison and Selection of Transformer Fluid

    Directory of Open Access Journals (Sweden)

    Lu Yang

    2016-01-01

    Full Text Available Transformer fluid directly affects the working state of the components and the cooling efficiency of transformer. There are three kinds of transformer fluid used for electric locomotive, EMU and suburban rail vehicles: mineral oil, silicone liquid and synthetic ester based insulating oil. In this paper, the three kinds of oil are compared from the fire safety, environmental protection, reliability and low maintenance. It provides a strong basis for the selection of transformer fluid. By comprehensive analysis, synthetic ester based insulating oil can completely replace mineral oil and silicone liquid. With rail transport safety and environmental protection standards improving, synthetic ester based insulating oil will be the best choice for transformer.

  16. Quantum Jarzynski equality of measurement-based work extraction.

    Science.gov (United States)

    Morikuni, Yohei; Tajima, Hiroyasu; Hatano, Naomichi

    2017-03-01

    Many studies of quantum-size heat engines assume that the dynamics of an internal system is unitary and that the extracted work is equal to the energy loss of the internal system. Both assumptions, however, should be under scrutiny. In the present paper, we analyze quantum-scale heat engines, employing the measurement-based formulation of the work extraction recently introduced by Hayashi and Tajima [M. Hayashi and H. Tajima, arXiv:1504.06150]. We first demonstrate the inappropriateness of the unitary time evolution of the internal system (namely, the first assumption above) using a simple two-level system; we show that the variance of the energy transferred to an external system diverges when the dynamics of the internal system is approximated to a unitary time evolution. Second, we derive the quantum Jarzynski equality based on the formulation of Hayashi and Tajima as a relation for the work measured by an external macroscopic apparatus. The right-hand side of the equality reduces to unity for "natural" cyclic processes but fluctuates wildly for noncyclic ones, exceeding unity often. This fluctuation should be detectable in experiments and provide evidence for the present formulation.

  17. Comparison of hemodynamics of intracranial aneurysms be