WorldWideScience

Sample records for based working fluids

  1. CO2-based mixtures as working fluids for geothermal turbines.

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven Alan; Conboy, Thomas M.; Ames, David E.

    2012-01-01

    Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for application to a variety of heat sources, including geothermal, solar, fossil, and nuclear power. This work is centered on the supercritical CO{sub 2} (S-CO{sub 2}) power conversion cycle, which has the potential for high efficiency in the temperature range of interest for these heat sources and is very compact-a feature likely to reduce capital costs. One promising approach is the use of CO{sub 2}-based supercritical fluid mixtures. The introduction of additives to CO{sub 2} alters the equation of state and the critical point of the resultant mixture. A series of tests was carried out using Sandia's supercritical fluid compression loop that confirmed the ability of different additives to increase or lower the critical point of CO{sub 2}. Testing also demonstrated that, above the modified critical point, these mixtures can be compressed in a turbocompressor as a single-phase homogenous mixture. Comparisons of experimental data to the National Institute of Standards and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties (REFPROP) Standard Reference Database predictions varied depending on the fluid. Although the pressure, density, and temperature (p, {rho}, T) data for all tested fluids matched fairly well to REFPROP in most regions, the critical temperature was often inaccurate. In these cases, outside literature was found to provide further insight and to qualitatively confirm the validity of experimental findings for the present investigation.

  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. Selection of organic Rankine cycle working fluid based on unit-heat-exchange-area net power

    Institute of Scientific and Technical Information of China (English)

    郭美茹; 朱启的; 孙志强; 周天; 周孑民

    2015-01-01

    To improve energy conversion efficiency, optimization of the working fluids in organic Rankine cycles (ORCs) was explored in the range of low-temperature heat sources. The concept of unit-heat-exchange-area (UHEA) net power, embodying the cost/performance ratio of an ORC system, was proposed as a new indicator to judge the suitability of ORC working fluids on a given condition. The heat exchange area was computed by an improved evaporator model without fixing the minimum temperature difference between working fluid and hot fluid, and the flow pattern transition during heat exchange was also taken into account. The maximum UHEA net powers obtained show that dry organic fluids are more suitable for ORCs than wet organic fluids to recover low-temperature heat. The organic fluid 1-butene is recommended if the inlet temperature of hot fluid is 353.15−363.15 K or 443.15−453.15 K, heptane is more suitable at 373.15−423.15 K, and R245ca is a good option at 483.15−503.15 K.

  4. Optimization of the working fluid for a sorption-based Joule-Thomson cooler

    NARCIS (Netherlands)

    Wu, Y.; Zalewski, D.R.; Vermeer, C.H.; Brake, ter H.J.M.

    2013-01-01

    Sorption-based Joule–Thomson coolers operate vibration-free, have a potentially long life time, and cause no electromagnetic interference. Therefore, they are appealing to a wide variety of applications, such as cooling of low-noise amplifiers, superconducting electronics, and optical detectors. The

  5. Analyzing the Effectiveness of Microlubrication Using a Vegetable Oil-Based Metal Working Fluid during End Milling AISI 1018 Steel

    Directory of Open Access Journals (Sweden)

    Vasim Shaikh

    2014-01-01

    Full Text Available Microlubrication minimizes the exposure of metal working fluids to the machining operators leading to an economical, safer, and healthier workplace environment. In this study, a vegetable oil-based lubricant was used to conduct wear analysis and to analyze the effectiveness of microlubrication during end milling AISI 1018 steel. A solid carbide cutting tool with bright oxide finish was used with varying cutting speed and feed rate having a constant depth of cut. Abrasion was the dominant wear mechanism for all the cutting tools under consideration. Other than abrasion, sliding adhesive wear of the workpiece materials was also observed. The scanning electron microscope investigation of the used cutting tools revealed microfatigue cracks, welded microchips, and unusual built-up edges on the cutting tools flank and rake side. A full factorial experiment was conducted and regression models were generated for both the sides of tool flank wear. The study shows that with a proper selection of the cutting parameters it is possible to obtain higher tool life.

  6. Synthetic Base Fluids

    Science.gov (United States)

    Brown, M.; Fotheringham, J. D.; Hoyes, T. J.; Mortier, R. M.; Orszulik, S. T.; Randles, S. J.; Stroud, P. M.

    The chemical nature and technology of the main synthetic lubricant base fluids is described, covering polyalphaolefins, alkylated aromatics, gas-to-liquid (GTL) base fluids, polybutenes, aliphatic diesters, polyolesters, polyalkylene glycols or PAGs and phosphate esters.Other synthetic lubricant base oils such as the silicones, borate esters, perfluoroethers and polyphenylene ethers are considered to have restricted applications due to either high cost or performance limitations and are not considered here.Each of the main synthetic base fluids is described for their chemical and physical properties, manufacture and production, their chemistry, key properties, applications and their implications when used in the environment.

  7. 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.

  8. The thermoelectric working fluid: Thermodynamics and transport

    Science.gov (United States)

    Benenti, Giuliano; Ouerdane, Henni; Goupil, Christophe

    2016-12-01

    Thermoelectric devices are heat engines, which operate as generators or refrigerators using the conduction electrons as a working fluid. The thermoelectric heat-to-work conversion efficiency has always been typically quite low, but much effort continues to be devoted to the design of new materials boasting improved transport properties that would make them of the electron crystal-phonon glass type of systems. On the other hand, there are comparatively few studies where a proper thermodynamic treatment of the electronic working fluid is proposed. The present article aims at contributing to bridge this gap by addressing both the thermodynamic and transport properties of the thermoelectric working fluid covering a variety of models, including interacting systems. xml:lang="fr"

  9. Laser-launched flyers with organic working fluids

    Science.gov (United States)

    Mulford, Roberta; Swift, Damian

    2003-10-01

    The TRIDENT laser has been used to launch flyers by depositing IR energy in a thin layer of material - the working fluid - sandwiched between the flyer and a transparent substrate. We have investigated the use of working fluids based on organics, chosen as they are quite efficient absorbers of IR energy and should also convert heat to mechanical work more efficiently than materials such as carbon. A thermodynamically complete equation of state was developed for one of the fluids investigated experimentally - a carbohydrate solution - by chemical equilibrium calculations using the CHEETAH program. Continuum mechanics simulations were made of the flyer launch process, modeling the effect of the laser as energy deposition in the working fluid, and taking into account the compression and recoil of the substrate. We compare the simulations with a range of experiments and demonstrate the optimization of substrate and fluid thickness for a given flyer thickness and speed.

  10. 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.

  11. Visualization of working fluid flow in gravity assisted heat pipe

    OpenAIRE

    Nemec Patrik; Malcho Milan

    2015-01-01

    Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapor and vice versa help heat pipe to transport high heat flux. The article deal about construction and processes casing in heat pipe during operation. Experiment visualization of working fluid flow is performed with glass heat pipe filed with ethanol. The visualization of working fluid flow explains the phenomena as working fl...

  12. Visualization of working fluid flow in gravity assisted heat pipe

    Directory of Open Access Journals (Sweden)

    Nemec Patrik

    2015-01-01

    Full Text Available Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapor and vice versa help heat pipe to transport high heat flux. The article deal about construction and processes casing in heat pipe during operation. Experiment visualization of working fluid flow is performed with glass heat pipe filed with ethanol. The visualization of working fluid flow explains the phenomena as working fluid boiling, nucleation of bubbles, vapor flow, vapor condensation on the wall, vapor and condensate flow interaction, flow down condensate film thickness on the wall, occurred during the heat pipe operation.

  13. Visualization of working fluid flow in gravity assisted heat pipe

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2015-05-01

    Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapor and vice versa help heat pipe to transport high heat flux. The article deal about construction and processes casing in heat pipe during operation. Experiment visualization of working fluid flow is performed with glass heat pipe filed with ethanol. The visualization of working fluid flow explains the phenomena as working fluid boiling, nucleation of bubbles, vapor flow, vapor condensation on the wall, vapor and condensate flow interaction, flow down condensate film thickness on the wall, occurred during the heat pipe operation.

  14. 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.

  15. Working fluid flow visualization in gravity heat pipe

    Directory of Open Access Journals (Sweden)

    Nemec Patrik

    2016-01-01

    Full Text Available Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapour and vice versa help heat pipe to transport high heat flux. The article deal about gravity heat pipe construction and processes casing inside during heat pipe operation. Experiment working fluid flow visualization is performed with two glass heat pipes with different inner diameter (13 mm and 22 mm and filled with water. The working fluid flow visualization explains the phenomena as a working fluid boiling, nucleation of bubbles, and vapour condensation on the wall, vapour and condensate flow interaction, flow down condensate film thickness on the wall occurred during the heat pipe operation.

  16. Working fluid flow visualization in gravity heat pipe

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2016-03-01

    Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapour and vice versa help heat pipe to transport high heat flux. The article deal about gravity heat pipe construction and processes casing inside during heat pipe operation. Experiment working fluid flow visualization is performed with two glass heat pipes with different inner diameter (13 mm and 22 mm) and filled with water. The working fluid flow visualization explains the phenomena as a working fluid boiling, nucleation of bubbles, and vapour condensation on the wall, vapour and condensate flow interaction, flow down condensate film thickness on the wall occurred during the heat pipe operation.

  17. Base isolation of fluid containers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. [Cygna Group Inc./ICF Kaiser International, Oakland, CA (United States)

    1995-12-01

    Fluid containers often constitute critical internal equipment in power plants. However, due to possible structure-equipment interaction effect they are particularly vulnerable during strong earthquake events. An effective technique for protecting fluid containers is base isolation. By deflecting the possible seismic input energy into the superstructure, base isolation can substantially reduce seismic demand on the containers, making it more cost effective than equivalent conventional design.

  18. Geothermal Reservoir Well Stimulation Program - Fracturing Fluid Evaluation (Laboratory Work)

    Energy Technology Data Exchange (ETDEWEB)

    None

    1982-01-01

    This report describes work done to characterize by chemical methods the temperature/ time degradation behavior of polymer based fluids that may be used in stimulating geothermal wells by fracturing. The polymers tested were hydroxypropulguar (HP guar), hydroxethylcellulose (HEC), carboxymethylcellulose (CMC), and XC Polymer. Also two commercially available cross-linked HP guar systems were tested. The report covers the development of analytical techniques for characterizing the polymers and the results of static and dynamic high temperature aging of the polymers in various salt water environments. The fluids were tested at 150, 200, and 250{degree}C. The report covers the implications of these results based on the time/ temperature degradation of the polymers and the relative ease of removing the degraded polymer from a sandpack. [DJE-2005

  19. 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...

  20. 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...

  1. Working fluids and expansion machines for ORC

    Science.gov (United States)

    Richter, Lukáš; Linhart, Jiří

    2016-06-01

    This paper discusses the key technical aspects of the Organic Rankin - Clausius cycle (ORC), unconventional technology with great potential for the use of low-potential heat and the use of geothermal and solar energy, and in connection with the burning of biomass. The principle of ORC has been known since the late 19th century. The development of new organic substances and improvements to the expansion device now allows full commercial exploitation of ORC. The right choice of organic working substances has the most important role in the design of ORC, depending on the specific application. The chosen working substance and achieved operating parameters will affect the selection and construction of the expansion device. For this purpose the screw engine, inversion of the screw compressor, can be used.

  2. 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.

  3. 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

    identify the target properties of the CAMD problem for working fluids. In this study the CAMD problem for the development of novel working fluids for organic Rankine cycles (ORC) is formulated mathematically. It integrates both a system model for the ORC and property models including the Peng...... will be applied in a case study of an Organic Rankine Cycle (ORC) with a low-temperature heat source. The heat source is a hot water stream from waste heat of a chemical site. Giving this pre-exquisite the method allows to identify the most favorable working fluid along with the corresponding optimal process...... conditions in order to get the highest possible power output. The study presents a new approach for the identification of target properties of CAMD problems based on sensitivity analysis and shows its application for the development of novel working fluids of organic Rankine cycles for low temperature heat...

  4. Physically-based fluid animation: A survey

    Institute of Scientific and Technical Information of China (English)

    TAN Jie; YANG XuBo

    2009-01-01

    In this paper, we give an up-to-date survey on physically-based fluid animation research. As one of the most popular approaches to simulate realistic fluid effects, physically-based fluid animation has spurred a large number of new results in recent years. We classify and discuss the existing methods within three categories: Lagrangian method, Eulerian method and Lattice-Boltzmann method. We then introduce techniques for seven different kinds of special fluid effects. Finally we review the latest hot research areas and point out some future research trends, including surface tracking, fluid control, hybrid method, model reduction, etc.

  5. Impact of working fluids on gravitational heat pipe performance

    Science.gov (United States)

    Jobb, Marián; Kosa, Ľuboš; Nosek, Radovan; Malcho, Milan

    2016-06-01

    Performance heat pipes depends on several parameters. This article deals with the performance of heat pipes, depending on the working fluid and operating temperature. There is described the essential function of the heat pipe manufacturing process. Stainless heat pipes were made of material AISI 304 and filled with a distilled water and solution of distilled water with silver nitrate, up to 20% of the heat pipe inner volume. Measurements were carried at an operating temperature of 40 °C to 90 °C. The performance was measured on the experimental device. Presented results show the progress of individual measurements and the effect of operating parameters and working fluid on the performance of heat pipes.

  6. Analysis of heat recovery of diesel engine using intermediate working fluid

    Science.gov (United States)

    Jin, Lei; Zhang, Jiang; Tan, Gangfeng; Liu, Huaming

    2017-02-01

    The organic Rankine cycle (ORC) is an effective way to recovery the engine exhaust heat. The thermal stability of the evaporation system is significant for the stable operation of the ORC system. In this paper, the performance of the designed evaporation system which combines with the intermediate fluid for recovering the exhaust waste heat from a diesel engine is evaluated. The thermal characteristics of the target diesel engine exhaust gas are evaluated based on the experimental data firstly. Then, the mathematical model of the evaporation system is built based on the geometrical parameters and the specific working conditions of ORC. Finally, the heat transfer characteristics of the evaporation system are estimated corresponding to three typical operating conditions of the diesel engine. The result shows that the exhaust temperature at the evaporator outlet increases slightly with the engine speed and load. In the evaporator, the heat transfer coefficient of the Rankine working fluid is slightly larger than the intermediate fluid. However, the heat transfer coefficient of the intermediate fluid in the heat exchanger is larger than the exhaust side. The heat transfer areas of the evaporator in both the two-phase zone and the preheated zone change slightly along with the engine working condition while the heat transfer areas of the overheated zone has changed obviously. The maximum heat transfer rate occurs in the preheating zone while the minimum value occurs in the overheating zone. In addition, the Rankine working fluid temperature at the evaporator outlet is not sensitively affected by the torque and speed of the engine and the organic fluid flow is relatively stable. It is concluded that the intermediate fluid could effectively reduce the physical changes of Rankine working fluid in the evaporator outlet due to changes in engine operating conditions.

  7. 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.

  8. Bio-based Hydraulic Fluids

    Science.gov (United States)

    2008-04-17

    currently formulated with vegetable oils (i.e., rapeseed , sun flower, corn, soybean, canola, coconut, etc.) and synthetic ester, such as polyol ester...2008 Vegetable Oil • Excellent lubrication • Nontoxic • Biodegradable • Derived from renewable resources such as rapeseed , sunflower, corn...Mineral Oil 100 SAE 15W-40 G Rapeseed 32 Commercial HF H Polyol ester 22 MIL-PRF-32073 Grade 2 I Canola - Cooking Oil *Hydraulic fluid 3717 April

  9. Effect of working fluids on organic Rankine cycle for waste heat recovery

    Energy Technology Data Exchange (ETDEWEB)

    Bo Tau Liu; Kuo Hsiang Chien; Chi Chuan Wang [Industrial Technology Research Inst., Hsinchu, Taiwan (China). Energy and Resources Lab.

    2004-06-01

    This study presents an analysis of the performance of organic Rankine cycle (ORC) subjected to the influence of working fluids. The effects of various working fluids on the thermal efficiency and on the total heat-recovery efficiency have been investigated. It is found that the presence of hydrogen bond in certain molecules such as water, ammonia, and ethanol may result in wet fluid conditions due to larger vaporizing enthalpy, and is regarded as inappropriate for ORC systems. The calculated results reveal that the thermal efficiency for various working fluids is a weak function of the critical temperature. The maximum value of the total heat-recovery efficiency occurs at the appropriate evaporating temperature between the inlet temperature of waste heat and the condensing temperature. In addition, the maximum value of total heat-recovery efficiency increases with the increase of the inlet temperature of the waste heat source and decreases it by using working fluids having lower critical temperature. Analytical results using a constant waste heat temperature or based on thermal efficiency may result in considerable deviation of system design relative to the varying temperature conditions of the actual waste heat recovery and is regarded as inappropriate. (author)

  10. 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

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

    Science.gov (United States)

    Mehta, R. N.; Bapat, S. L.; Atrey, M. D.

    2014-01-01

    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.

  12. 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.

  13. Thermodynamic equation of state approach for the choice of working fluids of absorption cooling cycles

    Science.gov (United States)

    Gomez, A. L.; Mansoori, G. A.

    1983-01-01

    A methodology is developed for the application of thermodynamic equations of state of fluids and fluid mixtures in evaluating working fluid combinations of absorption cooling cycles. Thermodynamic phase equilibrium formulation of this methodology is presented. In the application of this approach for the comparative study and choice of working fluids, the Redlich-Kwong equation of state is used for a number of possible working fluid combinations for solar absorption cooling cycles. It is demonstrated that when limited experimental data are at hand this approach could be a useful screening technique for potential working fluid combinations.

  14. Numerical Studies On Bubble Pump With Alternate Working Fluids

    Directory of Open Access Journals (Sweden)

    L. Bruno Augustin

    2013-10-01

    Full Text Available The importance of energy conservation in the context of growing global population and dwindling fossil fuel resources cannot be overemphasized. Energy can be conserved by using it more efficiently. The energy spent for an application should be of the correct amount and type. It would make more sense to spend heat energy for heating rather than the high grade electricity as most of the electric power in the world is generated from driving heat engines, for which heat is supplied from the combustion of fossil fuels. At the same time, depletion of these conventional resources also poses a serious problem in meeting energy requirements. In this paper, the bubble pump, which is an integral part of diffusion- absorption refrigeration system, has been investigated numerically .A thermally driven bubble pump, which can be powered by solar thermal energy, is used to lift the liquid. The bubble pump runs on solar energy and reduces the amount of energy spent by replacing the compressor in conventional vapour absorption refrigeration system. As a result of the absence of any mechanical moving part, the refrigerator is silent and very reliable in addition to an economical and environmental friendly device. The concept of such a pump is already in existence but optimization studies are yet to be extensively investigated. This paper deals with the comparison of various parameters of the bubble pump using water and Nonane as the working fluid. Numerical simulation of the bubble pump is carried out using simple numerical equations which assume slug flow in the bubble pump. The mass flow rate, the sensible heating time and position of heating element are varied and the effect it has on diameter of the pipe, pumping ratio and the heat required is studied for both the working fluids

  15. 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...

  16. 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.

  17. 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

    1989-12-31

    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.

  18. Theoretical study of ejector refrigeration system with working fluid R410a

    OpenAIRE

    Sandeep Kashyap; R.C. Gupta

    2011-01-01

    In this paper, simulation program is developed on based of one dimensional mathematical modal to analysis the performance ejector refrigeration cycle with working fluid R410a and also compared with performance of R134a. A performance comparison is made on various operating condition and ejector geometry. The result shows that performance of R134a is better than R410a for area ratio 5.64 and 7.84.

  19. Theoretical study of ejector refrigeration system with working fluid R410a

    Directory of Open Access Journals (Sweden)

    Sandeep Kashyap

    2011-08-01

    Full Text Available In this paper, simulation program is developed on based of one dimensional mathematical modal to analysis the performance ejector refrigeration cycle with working fluid R410a and also compared with performance of R134a. A performance comparison is made on various operating condition and ejector geometry. The result shows that performance of R134a is better than R410a for area ratio 5.64 and 7.84.

  20. 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.

  1. 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).

  2. Influence of regenerator matrix and working fluid on optimisation of design parameters of Stirling cryocoolers

    Science.gov (United States)

    Atrey, M. D.; Bapat, S. L.; Narayankhedkar, K. G.

    The performance of Stirling cryocooler is governed by principal designparameters. The optimum combination of these design parameters gives maximum refrigeration effect and minimum desired efforts. The performance of the cryocooler depends significantly on the regenerator functioning and the working fluids. The mesh size of the regenerator affects dead space, pressure drop, regenerator effectiveness, etc. The working fluids differ in their thermal properties and therefore affect the performance significantly, The present paper aims to study the influence of regenerator matrix and working fluids on these design parameters. The matrix material considered is Phosphor Bronze while the working fluids considered are Helium and Hydrogen.

  3. Fracturing-fluid evaluation (laboratory work). Geothermal-reservoir well-stimulation program

    Energy Technology Data Exchange (ETDEWEB)

    1982-01-01

    Work done to characterize by chemical methods the temperature/time degradation behavior of polymer based fluids that may be used in stimulating geothermal wells by fracturing is described. The polymers tested were hydroxypropylguar (HP guar), hydroxyethylcellulose (HEC), carboxymethylcellulose (CMC), and XC Polymer. Also, two commercially available cross-linked HP guar systems were tested. The development of analytical techniques for characterizing the polymers and the results of static and dynamic high temperature aging of the polymers in various salt water environments are covered. The fluids were tested at 150, 200 and 250/sup 0/C. The implications of these results based on the time/temperature degradation of the polymers and the relative ease of removing the degraded polymer from a sandpack are covered.

  4. 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.

  5. Working fluid concentration measurement in solar air conditioning systems

    Energy Technology Data Exchange (ETDEWEB)

    Romero, R.J.; Basurto-Pensado, M.A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001. Col. Chamilpa, C.P. 62210, Cuernavaca, Morelos (Mexico); Jimenez-Heredia, A.H.; Sanchez-Mondragon, J.J. [Departamento de Optica, Instituto Nacional de Astrofisica Optica y Electronica, Luis Enrique Erro No. 1, Tonantzintla, Apartado Postal 51 y 216, C.P. 72000, Puebla (Mexico)

    2006-02-15

    In order to evaluate on-line corrosive electrolyte concentration in solar air conditioning systems, an optical technique to determine the concentration is being proposed. With this optical sensing method, it is possible to measure the percentage concentration of the aqueous corrosive lithium bromide solution at temperatures ranging from 25{sup o}C to 70{sup o}C and a maximum concentration of 60%. The measurement system is based on the refractive index of the solution and the data correlation, at several temperature and concentration values. The results of this work present a direct method for concentration measurement of corrosive liquids and also show the correlation among the three parameters: refractive index, temperature and weight concentration. This correlation can be used to develop the optical device for solar air conditioning systems to control and improve efficiency. (author)

  6. Distribution of heat flux by working fluid in loop heat pipe

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2016-03-01

    The main topics of article are construction of loop heat pipe, thermal visualization of working fluid dynamics and research results interpretation. The work deals about heat flux transport by working fluid in loop heat pipe from evaporator to condenser evolution. The result of the work give us how the hydrodynamic and thermal processes which take place inside the loop of heat pipe affect on the overall heat transport by loop heat pipe at start-up and during operation.

  7. Distribution of heat flux by working fluid in loop heat pipe

    Directory of Open Access Journals (Sweden)

    Nemec Patrik

    2016-01-01

    Full Text Available The main topics of article are construction of loop heat pipe, thermal visualization of working fluid dynamics and research results interpretation. The work deals about heat flux transport by working fluid in loop heat pipe from evaporator to condenser evolution. The result of the work give us how the hydrodynamic and thermal processes which take place inside the loop of heat pipe affect on the overall heat transport by loop heat pipe at start-up and during operation.

  8. Thermal MEMS flow meter for gaseous working fluids on the basis of the hot-wire thermoanemometric sensor

    Science.gov (United States)

    Tsivinskaya, T. A.; Avaeva, L. G.; Grigoriev, P. V.; Mileshin, S. A.

    2016-10-01

    This paper describes the main principles of constructing innovative MEMS flow meters for gaseous working fluids. MEMS flow meter contains hot-wire thermoanemometrisc sensor which response to the temperature change caused by convective working fluid heat transfer from a hot-wire. The advantages of using hot-wire thermoanemometric sensors were analyzed. The main emphasis of this work is on speed, construction simplicity and small size of the sensor. The new approach to the solution of a problem of sensor output signal relation with the working fluid temperature is presented. This approach is based on adding an extra temperature sensor and a special scheme for thermal compensation to the hot-wire sensor. The temperature scale between temperature sensors (thermistors) corresponds to the flow speed and the flow rate.

  9. Development of an isolator working with magnetorheological elastomers and fluids

    Science.gov (United States)

    Sun, S. S.; Yang, J.; Li, W. H.; Du, H.; Alici, G.; Yan, T. H.; Nakano, Masami

    2017-01-01

    This paper reports an isolator whose damping and stiffness can be simultaneously controlled by magnetorheological (MR) fluids and MR elastomers. A hydraulically actuated MTS machine was used to test this variable stiffness and damping isolator after its prototype. The field-dependent responses including stiffness variability and damping variability, together with the amplitude-dependent response and frequency-dependent responses were separately tested and analyzed successively. The experimental results prove the successful implementation of the as-designed MRE-F isolator with obvious variable damping and stiffness. A new phenomenological model incorporating Bingham model and four-parameter model was developed to describe the dynamic properties of the isolator. The successful development, experimental testing, and modelling of this innovative variable stiffness and damping isolator make the concept of variable stiffness and damping become feasible.

  10. Verification strategies for fluid-based plasma simulation models

    Science.gov (United States)

    Mahadevan, Shankar

    2012-10-01

    Verification is an essential aspect of computational code development for models based on partial differential equations. However, verification of plasma models is often conducted internally by authors of these programs and not openly discussed. Several professional research bodies including the IEEE, AIAA, ASME and others have formulated standards for verification and validation (V&V) of computational software. This work focuses on verification, defined succinctly as determining whether the mathematical model is solved correctly. As plasma fluid models share several aspects with the Navier-Stokes equations used in Computational Fluid Dynamics (CFD), the CFD verification process is used as a guide. Steps in the verification process: consistency checks, examination of iterative, spatial and temporal convergence, and comparison with exact solutions, are described with examples from plasma modeling. The Method of Manufactured Solutions (MMS), which has been used to verify complex systems of PDEs in solid and fluid mechanics, is introduced. An example of the application of MMS to a self-consistent plasma fluid model using the local mean energy approximation is presented. The strengths and weaknesses of the techniques presented in this work are discussed.

  11. Working fluids of a low-temperature geothermally-powered Rankine cycle for combined power and heat generation system

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel combined power and heat generation system 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 advantages of the novel combined power and heat generation system are free of using additional cooling water circling system for the power generation subsystem as well as maximizing the use of thermal energy in the low-temperature geothermal source. The main purpose is to identify suitable working fluids (wet, isentropic and dry flu-ids) 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. Parameters under investigation were evaporating temperature, PPR value and QQR value. Results indicate that there exits an optimum evaporating temperature to maximize the PPR value and minimize the QQR value at the same time for individual fluid. And dry fluids show higher PPR values but lower QQR values. NH3 and R152a outstand among wet fluids. R134a out-stands among isentropic fluids. R236ea, R245ca, R245fa, R600 and R600a outstand among dry fluids. R236ea shows the highest PPR value among the recommended fluids.

  12. Agent-Based Chemical Plume Tracing Using Fluid Dynamics

    Science.gov (United States)

    Zarzhitsky, Dimitri; Spears, Diana; Thayer, David; Spears, William

    2004-01-01

    This paper presents a rigorous evaluation of a novel, distributed chemical plume tracing algorithm. The algorithm is a combination of the best aspects of the two most popular predecessors for this task. Furthermore, it is based on solid, formal principles from the field of fluid mechanics. The algorithm is applied by a network of mobile sensing agents (e.g., robots or micro-air vehicles) that sense the ambient fluid velocity and chemical concentration, and calculate derivatives. The algorithm drives the robotic network to the source of the toxic plume, where measures can be taken to disable the source emitter. This work is part of a much larger effort in research and development of a physics-based approach to developing networks of mobile sensing agents for monitoring, tracking, reporting and responding to hazardous conditions.

  13. Optimization of metal working fluids treatment using calcium chloride by response surface methodology

    Directory of Open Access Journals (Sweden)

    HA. Jamali

    2016-11-01

    Full Text Available Background: Extensive use of metal working fluids degrades their chemical composition. They should be treated using a safe method. Chemical coagulation-flocculation process is one the treatment methods. Objective: The aim of this study was to optimize the coagulation-flocculation process using calcium chloride in metal working fluids treatment. Methods: This laboratory based study was performed in School of Health affiliated to Qazvin University of Medical Sciences in 2014. Using calcium chloride and a six-compartment jar, the efficiency of coagulation-flocculation process was assessed for removal of chemical oxygen demand (COD and turbidity and amount of released oil. Central composite design (CCD and response surface methodology (RSM were applied to optimize the treatment operation parameters (pH and dosage of coagulant. Quadratic models were developed for calculation of the three responses (COD, turbidity, and released oil. Findings: The optimum condition for coagulation-flocculation process was seen after treatment with 4.2 g/L calcium chloride at pH 3.71 in which COD and turbidity removal efficiency were 93% and 96.9%, respectively and the amount of released oil was 31.8 ml. The level of desirability was 91.2%. The values of laboratory study were in good agreement with the values predicted by the model. Conclusion: Metal working fluids treatment with calcium chloride was efficient in the removal of pollution parameters. Dosage of calcium chloride was similar to the conventional coagulants such as Alum, but its efficiency was higher.

  14. 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

  15. Evaluation of Active Working Fluids for Brayton Cycles in Space Applications

    Science.gov (United States)

    Conklin, J. C.; Courville, G. E.; Scott, J. H.

    2004-02-01

    The main parameter of interest for space thermal power conversion to electricity is specific power, defined as the total electric power output per unit of system mass, rather than the cycle thermal efficiency. For a closed Brayton cycle, performance with two active working fluids, nitrogen tetroxide and aluminum chloride, is compared to that with an inert mixture of helium and xenon having a molecular mass of 40. A chemically active working fluid is defined here as a chemical compound that has a relatively high molecular weight at temperatures appropriate for the compressor inlet and dissociates to a lighter molecular weight fluid at typical turbine inlet temperatures. The active working fluids may have the advantage of a higher net turbomachinery work output and an advantageous enhancement of the heat transfer coefficient in the heat exchangers. The fundamental theory of the active working fluid concept is presented to demonstrate these potential advantages. Scoping calculations of the heat exchanger mass for a selected spacecraft application of 36.4 kW of electrical power output show that the nitrogen tetroxide active working fluid has an advantageous 7% to 30% lower mass-to-power ratio than that for the inert noble gas mixture, depending on the allowable turbine inlet temperature. The calculations for the aluminum chloride system suggest only a slight improvement in performance relative to the inert noble gas mixture.

  16. 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

  17. Effect of surface texture and working gap on the braking performance of the magnetorheological fluid brake

    Science.gov (United States)

    Wang, Na; Li, Dong Heng; Li Song, Wan; Chao Xiu, Shi; Zhi Meng, Xiang

    2016-10-01

    In this paper, the effect of the surface textures of braking disc on the braking performance is experimentally investigated under the conditions of different working gaps and applied currents. For this purpose, a new configuration of magnetorheological fluid brake (MRB) with adjustable working gap is developed to improve the manufacturing accuracy and cost, and to reduce the problem of replacing the braking disc. In addition, the braking discs with three types of surface texture are designed and machined. Based on the test bed developed for the proposed MRB, a series of experiments are carried out on the manufactured prototype and the results are presented to obtain the relationship among the surface texture of the braking disc, applied current, working gap and the braking performance. The results show that the braking torque is significantly influenced by the working gap and surface texture of the braking disc, and the maximum braking torque is obtained on the conditions of 0.25 mm working gap and the braking disc with square surface texture.

  18. The effect of Bond number on pool boiling for mini-fin surfaces and different working fluids

    Science.gov (United States)

    Strąk, Ewelina; Pastuszko, Robert

    2016-03-01

    Experimental nucleate pool boiling data were collected for structures in the form of extended surfaces sintered with perforated foil. The article describes experimental investigations for two kinds of surfaces: smooth and mini-fins with sintered perforated foil (MFP). The MFP surfaces were manufactured out of perforated copper foil (pore diameters: 0.05 - 0.3 mm) sintered with the mini-fins, uniformly spaced on the base surface. The experiments were carried out at atmospheric pressure for four kinds of the fluids: water, ethanol, FC-72 and Novec 649. The results for these working fluids were compared in terms of the Bond number and other dimensionless parameters. For all working fluids, the heat transfer coefficients obtained for the MFP surfaces were from 2 to 5 times higher than those for the smooth surface. Using a regression analysis with reference to selected physical properties and several characteristic dimensions, it was possible to develop a correlation for the Nusselt number.

  19. 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.

  20. Criteria for selection of working fluid in low-temperature ORC

    Directory of Open Access Journals (Sweden)

    Mikielewicz Dariusz

    2016-09-01

    Full Text Available The economics of an ORC system is strictly linked to thermodynamic properties of the working fluid. A bad choice of working fluid could lead to a less efficient and expensive plant/generation unit. Some selection criteria have been put forward by various authors, incorporating thermodynamic properties, provided in literature but these do not have a general character. In the paper a simple analysis has been carried out which resulted in development of thermodynamic criteria for selection of an appropriate working fluid for subcritical and supercritical cycles. The postulated criteria are expressed in terms of non-dimensional numbers, which are characteristic for different fluids. The efficiency of the cycle is in a close relation to these numbers. The criteria are suitable for initial fluid selection. Such criteria should be used with other ones related to environmental impact, economy, system size, etc. Examples of such criteria have been also presented which may be helpful in rating of heat exchangers, which takes into account both heat transfer and flow resistance of the working fluid.

  1. 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

    Among the different renewable sources of energy, solar power could play a primary role in the development of a more sustainable electricity generation system. While large scale concentrated solar power plants based on the steam Rankine cycle have already been proved to be cost effective, research...... 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...... is still under progress for small scale low temperature solar-driven power plants. The steam Rankine cycle is suitable for high temperature applications, but its efficiency drastically decreases as the heat source temperature drops. In these cases a much more promising configuration is the organic Rankine...

  2. 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℃.

  3. Characterization of Fluid Flow in Paper-Based Microfluidic Systems

    Science.gov (United States)

    Walji, Noosheen; MacDonald, Brendan

    2014-11-01

    Paper-based microfluidic devices have been presented as a viable low-cost alternative with the versatility to accommodate many applications in disease diagnosis and environmental monitoring. Current microfluidic designs focus on the use of silicone and PDMS structures, and several models have been developed to describe these systems; however, the design process for paper-based devices is hindered by a lack of prediction capability. In this work we simplify the complex underlying physics of the capillary-driven flow mechanism in a porous medium and generate a practical numerical model capable of predicting the flow behaviour. We present our key insights regarding the properties that dictate the behaviour of fluid wicking in paper-based microfluidic devices. We compare the results from our model to experiments and discuss the application of our model to design of paper-based microfluidic devices for arsenic detection in drinking water in Bangladesh.

  4. 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.

  5. EFFECT OF WORKING FLUID AND FILLING RATIO ON PERFORMANCE OF A CLOSED LOOP PULSATING HEAT PIPE

    Directory of Open Access Journals (Sweden)

    E. R. BABU

    2016-06-01

    Full Text Available This paper presents preliminary experimental results on thermal performance of a closed loop pulsating heat pipe (CLPHP using copper tube having internal and external diameter with 2 mm and 3 mm respectively. For the experimentation, filling ratio (FR was varied from 30 % to 70% with 10% increments, four turns and different heat inputs of 10 to 22 W(Watts is supplied to PHP’s. The position of the PHP’s was vertical bottom heat mode. The length of evaporator, adiabatic and condenser section was maintained 55, 80, and 50 mm respectively. The working fluids are selected as Acetone, Methanol, Ethanol, CCL4 (Carbon Tetrachloride, and Benzene. In this study, characteristics of the thermal resistance and average evaporator temperatures at different heat input for various working fluids have been determined. The result shows that, the thermal resistance decreases rapidly with the increase of the heating input from 10 to 22 W. Further, slowly was extended on different working fluids as mentioned. From the experimental results, Acetone was found to be better working fluid as compared to other fluids.

  6. Nanostructured fluids from degradable nonionic surfactants for the cleaning of works of art from polymer contaminants.

    Science.gov (United States)

    Baglioni, M; Raudino, M; Berti, D; Keiderling, U; Bordes, R; Holmberg, K; Baglioni, P

    2014-09-21

    Nanostructured fluids containing anionic surfactants are among the best performing systems for the cleaning of works of art. Though efficient, their application may result in the formation of a precipitate, due to the combination with divalent cations that might leach out from the artifact. We propose here two new aqueous formulations based on nonionic surfactants, which are non-toxic, readily biodegradable and insensitive to the presence of divalent ions. The cleaning properties of water-nonionic surfactant-2-butanone (MEK) were assessed both on model surfaces and on a XIII century fresco that could not be cleaned using conventional methods. Structural information on nanofluids has been gathered by means of small-angle neutron scattering, dynamic light scattering and nuclear magnetic resonance with diffusion monitoring. Beside the above-mentioned advantages, these formulations turned out to be considerably more efficient in the removal of polymer coatings than those based on anionic surfactants. Our results indicate that the cleaning process most likely consists of two steps: initially, the polymer film is swollen by the MEK dissolved in the continuous domain of the nanofluid; in the second stage, surfactant aggregates come into play by promoting the removal of the polymer film with a detergency-like mechanism. The efficiency can be tuned by the composition and nature of amphiphiles and is promoted by working as close as possible to the cloud point of the formulation, where the second step proceeds at maximum rate.

  7. 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...... mixturesare usually degraded compared to an ideal mixture heat transfer coefficient linearly interpolatedbetween the pure fluid values. This entails a need for larger and more expensive heat exchangers. Previousstudies primarily focus on the thermodynamic benefits of zeotropic mixtures by employing firstand...... second law analyses. In order to assess the feasibility of using zeotropic mixtures, it is, however,important to consider the additional costs of the heat exchangers. In this study, we aim at evaluatingthe economic feasibility of zeotropic mixtures compared to pure fluids. We carry out a multi...

  8. 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

  9. 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.

  10. 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.

  11. Modelling the absorption refrigeration cycle using partially miscible working fluids by group contribution methods

    Science.gov (United States)

    Larkeche, O.; Meniai, A.-H.; Cachot, T.

    2012-06-01

    The present study concerns the cycle performance modelling of a particular configuration of an absorption refrigeration machine based on phase separation as well as development of a strategy for computer aided design of absorbents. The model uses predictive methods based on the group contribution concept for the computation of the thermodynamic phase equilibria involved such as liquid-liquid and vapour-liquid as well as enthalpy-concentration diagrams. The proposed absorbents computer-aided design strategy is based on the exploration of a number of structural group combinations obtained from a selected set of functional groups, according to the chemistry laws. The model was tested on four different absorbent-refrigerant pairs reported in the literature, namely (benzyl ethyl amine-glycerol), (water-hexanoic acid), (water-2-hexanone) and (water-ethyl propionate) as well as on pairs where the absorbent compound is generated by the proposed absorbent design strategy and the refrigerant is water. The results show that quite good values of the coefficient of performance (COP) can be obtained, indicating that this cycle configuration is promising and energetically efficient, mainly due to hardware savings, i.e. absence of condenser. However, other working fluid combinations have to be tested using the proposed model.

  12. 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

  13. Analysis on optimal working fluid flowrate and unstable power generation for miniaturized ORC systems

    Institute of Scientific and Technical Information of China (English)

    刘克涛; 朱家玲; 胡开永; 吴秀杰

    2016-01-01

    For efficient utilization of a limited geothermal resource in practical projects, the cycle parameters were comprehensively analyzed by combining with the heat transfer performance of the plate heat exchanger, with a variation of flowrate of R245fa. The influence of working fluid flowrate on a 500W ORC system was investigated. Adjusting the working fluid flowrate to an optimal value results in the most efficient heat transfer and hence the optimal heat transfer parameters of the plate heat exchanger can be determined. Therefore, for the ORC systems, optimal working fluid flowrate should be controlled. Using different temperature hot water as the heat source, it is found that the optimal flowrate increases by 6−10 L/h with 5 ℃ increment of hot water inlet temperature. During experiment, lower degree of superheat of the working fluid at the outlet the plate heat exchanger may lead to unstable power generation. It is considered that the plate heat exchanger has a compact construction which makes its bulk so small that liquid mixture causes the unstable power generation. To avoid this phenomenon, the flow area of plate heat exchanger should be larger than the designed one. Alternatively, installing a small shell and tube heat exchanger between the outlet of plate heat exchanger and the inlet of expander can be another solution.

  14. An Analysis of the Thermodynamic Cycle and Possible Working Fluids for a Space Heat Rejection System

    Science.gov (United States)

    1960-08-12

    absorption cross section - the neutron absorption cross section should be low to assure reliable long-term operation with the nuclear re- actor heat...and structure. For the power cycle as considered In this paper, the fol- lowing properties of the working fluid are also of interest: (1) Neutron

  15. 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$.

  16. The fluid dynamics of work transfer in the non-uniform viscous rotating flow within a Tesla disc turbomachine

    Science.gov (United States)

    Guha, Abhijit; Sengupta, Sayantan

    2014-03-01

    In this article, the fluid dynamics of work transfer within the narrow spacing (usually of the order of 100 μm) of multiple concentric discs of a Tesla disc turbomachine (turbine or compressor) has been analysed theoretically and computationally. Both the overall work transfer and its spatial development have been considered. It has been established that the work transfer mechanism in a Tesla disc turbomachine is very different from that in a conventional turbomachine, and the formulation of the Euler's work equation for the disc turbomachine contains several conceptual subtleties because of the existence of complex, three dimensional, non-uniform, viscous flow features. A work equivalence principle has been enunciated, which establishes the equality between the magnitudes of work transfer determined rigorously from two different approaches—one based on the shear stress acting on the disc surfaces and the other based on the change in angular momentum of the fluid. Care is needed in identifying the shear stress components that are responsible for the generation or absorption of useful power. It is shown from the Reynolds transport theorem that mass-flow-averaged tangential velocities (as opposed to the normally used area-averaged values) must be used in determining the change in angular momentum; the calculation has to be carefully formulated since both radial velocity (that determines throughput) and tangential velocity (that generates torque) depend strongly on the coordinate perpendicular to the disc surfaces. The principle of work transfer has been examined both in the absolute and relative frames of reference, revealing the subtle role played by Coriolis force. The concept of a new non-dimensional quantity called the torque potential fraction (Δ tilde H) is introduced. The value of Δ tilde H at any radial position increases with a decrease in inter-disc spacing. The computational fluid dynamic analysis shows that, for small value of inter-disc spacing and

  17. Global 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

    2016-01-01

    study involving the design of a working fluid for an Organic Ranking Cycle (ORC) design for power generation. Morris Screening is found to be favorable over Monte Carlo based standard regression. Monte Carlo based standard regression cannot be applied, because the current model cannot be sufficiently......This study compares two methods for global sensitivity analysis as a new approach for the identification and ranking of target properties in molecular design problems: A modified Morris Screening technique and Monte Carlo based standard regression. The two methodologies are highlighted in a case...

  18. Influence of Heat Input, Working Fluid and Evacuation Level on the Performance of Pulsating Heat Pipe

    Directory of Open Access Journals (Sweden)

    K. Rama Narasimha

    2012-01-01

    Full Text Available An experimental study on pulsating heat pipe (PHP is presented in this work. A closed loop PHP with a single U turn is fabricated and tested. The transient and steady state experiments are conducted and operating temperatures are measured. The experiments are carried out for different working fluids, heat input and for different evacuation levels. The derived parameters include thermal resistance and heat transfer coefficient of PHP. The results of these experiments show an intermittent motion of the working fluid at lower heat input. The temperature difference between evaporator and condenser at steady state is found lower for acetone compared to water, ethanol and methanol. Lower value of thermal resistance and higher value of heat transfer coefficient are observed in case of acetone compared to water, ethanol and methanol. Lower values of temperature difference between evaporator and condenser and thermal resistance and higher value of heat transfer coefficient are observed at atmospheric conditions of operation of PHP compared to evacuation conditions. The Power Spectral Density Analysis is also carried out on the results of these experiments using FFT technique to analyse the pulsating motion of the fluid in a PHP. In the Power Spectral Density analysis, the frequency distribution of temperature variation in PHP was observed over a wider range, signifying the periodic motion in the fluid flow of the liquid slug and vapour plug. This characteristic frequency corresponded to the characteristic time for a couple of adjacent vapour plug and liquid slug passing through a specific local wall surface in a PHP.

  19. Micromachined Inclinometer Based on Fluid Convection

    CERN Document Server

    Crespy, N; Combette, P; Boyer, P Temple; Giani, A; Foucaran, A

    2008-01-01

    This paper presents a numerical simulation and experimental results of a one-dimensional thermal inclinometer with the cavity filled of gas and liquid. The sensor principle consists of one heating resistor placed between two detectors. When the resistor is electrically powered, it creates a symmetrical temperature profile inside a micromachined silicon cavity. By applying a tilt to the sensor, the profile shifts in the same direction of the sensible axis corresponding to the horizontal one to one. The temperature profile and the sensitivity according to the CO2 gas and mineral oil SAE50 have been studied using numerical resolution of fluid dynamics equations with the computational fluid dynamics (CFD) software package Fluent V6.2. We have shown that the sensitivity of liquid sensors is higher than the gas sensors one. By using micromachined silicon technique, a thermal inclinometer with one pair of detectors placed at 300 um from the heater has been made. Experimental measurements corroborate with the numeric...

  20. 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

  1. Scanning Probe Microscope-Based Fluid Dispensing

    Directory of Open Access Journals (Sweden)

    Murali Krishna Ghatkesar

    2014-10-01

    Full Text Available 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 increasing. Therefore, integration of various technologies with numerous functionalities in one single device is important. Scanning probe microscope (SPM is one such device that has evolved from atomic force microscope for imaging to a variety of microscopes by integrating different physical and chemical mechanisms. In this article, we review a particular class of SPM devices that are suited for fluid dispensing. We review their fabrication methods, fluid-pumping mechanisms, real-time monitoring of dispensing, physics of dispensing, and droplet characterization. Some of the examples where these probes have already been applied are also described. Finally, we conclude with an outlook and future scope for these devices where femtolitre or smaller volumes of liquid handling are needed.

  2. 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

  3. 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.

  4. Thermodynamic properties of a geothermal working fluid; 90% isobutane-10% isopentane: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Gallagher, J.S.; Linsky, D.; Morrison, G.; Levelt Sengers, J.M.H.

    1987-04-01

    We present tables of thermodynamic properties, and dew and bubble properties, of a mixture of 90 mol % isobutane and 10 mol % isopentane, a working fluid in a binary geothermal power cycle. The tables are generated by a formulation of the Helmholtz free energy, in which the mixture properties are mapped onto the known properties of pure isobutane by means of the principle of generalized corresponding states. The data base for the Helmholtz free energy formulation is new. We report data obtained in three different apparatus: critical-line and isopentane vapor pressure data obtained in a visual cell; vapor-liquid equilibria data obtained in a mercury-operated variable-volume cell; and pressure-volume-temperature data for the 90 mol %-10 mol % mixture obtained in a semi-automated Burnett-isochoric apparatus. The principles of the methods, and estimates of the reliability, are discussed and all experimental data are compared with the surface. The results are tables of specific volume, enthalpy, entropy, specific heat and density and temperature derivatives of the pressure at 10 K temperature increments from 240 to 600 K along isobars from 0.01 to 20 MPa. Separate tables are prepared from the dew and bubble properties of the 90-10 mixture. Estimates of the effects of isomeric impurity of isobutane are given in graphical form.

  5. Magnetorheological properties of sodium sulphonate capped electrolytic iron based MR fluid: a comparison with CI based MR fluid

    Science.gov (United States)

    Vinod, Sithara; John, Reji; Philip, John

    2017-02-01

    Magnetorheological fluids have numerous engineering applications due to their interesting field assisted rheological behavior. Most commonly used dispersed phase in MR fluids is carbonyl iron (CI). The relatively high cost of CI warrants the need to develop cheaper alternatives to CI, without compromising rheological properties. With the above goal in mind, we have synthesized sodium sulphonate capped electrolytic iron based MR fluid and studied their magnetorheological properties. The results are compared with that of CI based MR fluid. EI and CI particles of average particle size of ∼10 μm with fumed silica particles additives are used in the present study. The dynamic yield stress for EI and CI based MR fluid were found to vary with field strength with an exponent of roughly 1.2 and 1.24, respectively. The slightly lower static and dynamic yield stress values of EI based MR fluid is attributed to the lower magnetization and polydispersity values. The dynamic yield stress showed a decrease of 18.73% and 61.8% for field strengths of 177 mT and 531 mT, respectively as the temperature was increased from 293 to 323 K. The optorheological studies showed a peak in the loss moduli, close to the crossover point of the storage and loss moduli, due to freely moving large sized aggregates along the shear direction that are dislodged from the rheometer plates at higher strains. Our results suggests that EI based MR fluids have magnetorheological behavior comparable to that of CI based MR fluids. As EI is much cheaper than CI, our findings will have important commercial implications in producing cost effective EI based MR fluids.

  6. THERMO-HYDRO-MECHANICAL MODELING OF WORKING FLUID INJECTION AND THERMAL ENERGY EXTRACTION IN EGS FRACTURES AND ROCK MATRIX

    Energy Technology Data Exchange (ETDEWEB)

    Robert Podgorney; Chuan Lu; Hai Huang

    2012-01-01

    Development of enhanced geothermal systems (EGS) will require creation of a reservoir of sufficient volume to enable commercial-scale heat transfer from the reservoir rocks to the working fluid. A key assumption associated with reservoir creation/stimulation is that sufficient rock volumes can be hydraulically fractured via both tensile and shear failure, and more importantly by reactivation of naturally existing fractures (by shearing), to create the reservoir. The advancement of EGS greatly depends on our understanding of the dynamics of the intimately coupled rock-fracture-fluid-heat system and our ability to reliably predict how reservoirs behave under stimulation and production. Reliable performance predictions of EGS reservoirs require accurate and robust modeling for strongly coupled thermal-hydrological-mechanical (THM) processes. Conventionally, these types of problems have been solved using operator-splitting methods, usually by coupling a subsurface flow and heat transport simulators with a solid mechanics simulator via input files. An alternative approach is to solve the system of nonlinear partial differential equations that govern multiphase fluid flow, heat transport, and rock mechanics simultaneously, using a fully coupled, fully implicit solution procedure, in which all solution variables (pressure, enthalpy, and rock displacement fields) are solved simultaneously. This paper describes numerical simulations used to investigate the poro- and thermal- elastic effects of working fluid injection and thermal energy extraction on the properties of the fractures and rock matrix of a hypothetical EGS reservoir, using a novel simulation software FALCON (Podgorney et al., 2011), a finite element based simulator solving fully coupled multiphase fluid flow, heat transport, rock deformation, and fracturing using a global implicit approach. Investigations are also conducted on how these poro- and thermal-elastic effects are related to fracture permeability

  7. Evaluation of behavior of biodegradable lubricants in the differential sticking coefficient of water based drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, L.V. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais], E-mail: luciana@dem.ufcg.edu.br; Nascimento, R.C.A.M. [Universidade Federal de Campina Grande (PPGCEMat/UFCG), PB (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Lira, D.S. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica; Magalhaes, J. [System Mud Fluidos de Perfuracao, Itajai, SC (Brazil). Dept. de Quimica

    2011-10-15

    This work aims to evaluate the behavior of four samples of biodegradable lubricants in the differential sticking coefficient of aqueous drilling fluids. Eighteen formulations of fluids containing bentonite clay, lubricants and biodegradable polymers in different concentrations were studied. The experiment focused on observing the samples' rheological properties, its filtration, the cake thickness, the lubricity coefficient, and, finally, the coefficient of the differential sticking. The results showed that the polymer additives improved rheological and filtration properties significantly. Also, the findings confirmed the idea that the presence of a lubricant leads to a reduction in lubricity, LC, and affects the differential sticking coefficient, DSC, of the fluids. However, the experiment observed a small variation on the LC as a result of an increase in the lubricant content. Overall, the results of the LC and the DSC of the fluids containing biodegradable lubricant additives were outstanding, being similar to the ones observed for oil-based fluids. (author)

  8. Organic rankine cycle with positive displacement expander and variable working fluid composition

    OpenAIRE

    2016-01-01

    Organic Rankine Cycles are often used in the exploitation of low-temperature heat sources. The relatively small temperature differential available to these projects makes them particularly vulnerable to changing ambient conditions, especially if an air-cooled condenser is used. The authors have recently demonstrated that a dynamic ORC with a variable working fluid composition, tuned to match the condensing temperature with the heat sink, can be used to achieve a considerable increase in year-...

  9. Training working memory and fluid intelligence in older adults: developing measures and exploring outcomes

    OpenAIRE

    Hynes, Sinéad

    2013-01-01

    This thesis investigates computerised cognitive training in older adults, with a focus on training working memory and fluid intelligence. A series of studies is reported, with two broad aims. The first was to develop and validate outcome measures appropriate for use in this population, and the second was to examine whether established gains in cognitive functioning generalised to everyday life. In relation to the first aim, two studies were conducted which concerned the development of a se...

  10. Carbon dioxide-based supercritical fluids as IC manufacturing solvents

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Davenhall, L.B.; Taylor, C.M.V.; Sivils, L.D.; Pierce, T.; Tiefert, K.

    1999-05-11

    The production of integrated circuits (IC's) involves a number of discrete steps which utilize hazardous or regulated solvents and generate large waste streams. ES&H 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}). Research work, conducted at Los Alamos in conjunction with the Hewlett-Packard Company, has lead to the development of a CO{sub 2}-based supercritical fluid treatment system for the stripping of hard-baked photoresists. This treatment system, known as Supercritical CO{sub 2} Resist Remover, or CORR, uses a two-component solvent composed of a nonhazardous, non-regulated compound, dissolved in supercritical CO{sub 2}. The solvent/treatment system has been successfully tested on metallized Si wafers coated with negative and positive photoresist, the latter both before and after ion-implantation. A description of the experimental data will be presented. Based on the initial laboratory results, the project has progressed to the design and construction of prototype, single-wafer photoresist-stripping equipment. The integrated system involves a closed-loop, recirculating cycle which continuously cleans and regenerates the CO{sub 2}, recycles the dissolved solvent, and separates and concentrates the spent resist. The status of the current design and implementation strategy of a treatment system to existing IC fabrication facilities will be discussed. Additional remarks will be made on the use of a SCORR-type system for the cleaning of wafers prior to processing.

  11. 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

  12. 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.

  13. 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 geothermal power plant has been developed. Started with two ordinary single flash power plants named unit 1 and unit 2, with the temperature 250°C resulting power is W1'+W2'. The power is enhanced by utilizing the steam that is out from first stage of the turbine by inputting the steam to the third stage, the power of the plant increase with W1''+W2" or 10% from the original power. By using flasher, the water from unit 1 and 2 is re-flashed at 200°C, and the steam is used to drive the turbine in unit 3, while the water is re-flashed at the temperature170°C and the steam is flown to the same turbine (unit 3) resulting the power of W3+W4. Using the 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

  14. APHRON-BASED DRILLING FLUIDS: SOLUTION FOR LOW PRESSURE RESERVOIRS

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2009-12-01

    Full Text Available Drilling wells throughout depleted or low pressure reservoirs requires low density drilling fluids, often with density less than water. Methods to reduce the density of drilling fluids have included mixing-in air or nitrogen. However, problems with these approaches include instability of gas bubbles (bubbles collapse or expand and increased costs. Recently, the use of micro bubbles named aphrons in drilling, completion and workover fluids has proven success in solving many problems related to low pressure reservoirs such as fluid loss control, formation damage, stabilization of multipressure sequences with one fluid and possible differential sticking. Aphrons represent bubble with uniquely structure stabilized with surfactant. Against conventional micro bubbles, aphrons are more stable in downhole conditions and they are generated using standard mixing equipment. Owing to their properties and overpressure in wellbore aphrons penetrate into low pressure layers and set up inner bridging. Depleted wells which are very expensive to drill underbalanced or with other remediation techniques can now be drilled overbalanced. This paper presents description of aphron structure and stability, aphron bridging mechanism, aphron-based fluid composition and properties, and field experiences in applying aphron-based fluids.

  15. 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

    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...... 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 (0.65/0.35mole). The results indicate that R32/R134a is the best of these fluids, with 3.4 % higher net power than R32...

  16. CFD modelling and experimental investigation of an ejector refrigeration system using methanol as the working fluid

    Energy Technology Data Exchange (ETDEWEB)

    Riffat, S.B.; Omer, S.A. [Nottingham Univ., School of the Built Environment, Nottingham (United Kingdom)

    2001-07-01

    This paper presents results of computational fluid dynamic (CFD) analysis and experimental investigation of an ejector refrigeration system using methanol as the working fluid. The CFD modelling was used to investigate the effect of the relative position of the primary nozzle exit within the mixing chamber on the performance of the ejector. The results of the CFD were used to obtain the optimum geometry of the ejector, which was then used to design, construct and test a small-scale experimental ejector refrigeration system. Methanol was used as the working fluid, as it has the advantage of being an 'environmentally friendly' refrigerant that does not contribute to global warming and ozone layer depletion. In addition, use of methanol allows the ejector refrigeration system to produce cooling at temperatures below the freezing point of the water, which of course would not be possible with a water ejector refrigeration system. CFD results showed that positioning the nozzle exit at least 0.21 length of the mixing chamber throat's diameter upstream of the entrance of the mixing chamber gave better performance than pushing it into the mixing chamber. Experimental values of coefficient of performance (COP) between 0.2 and 0.4 were obtained at operating conditions achievable using low-grade heat such as solar energy and waste heat. (Author)

  17. Soy Protein Isolate As Fluid Loss Additive in Bentonite-Water-Based Drilling Fluids.

    Science.gov (United States)

    Li, Mei-Chun; Wu, Qinglin; Song, Kunlin; Lee, Sunyoung; Jin, Chunde; Ren, Suxia; Lei, Tingzhou

    2015-11-11

    Wellbore instability and formation collapse caused by lost circulation are vital issues during well excavation in the oil industry. This study reports the novel utilization of soy protein isolate (SPI) as fluid loss additive in bentonite-water based drilling fluids (BT-WDFs) and describes how its particle size and concentration influence on the filtration property of SPI/BT-WDFs. It was found that high pressure homogenization (HPH)-treated SPI had superior filtration property over that of native SPI due to the improved ability for the plugging pore throat. HPH treatment also caused a significant change in the surface characteristic of SPI, leading to a considerable surface interaction with BT in aqueous solution. The concentration of SPI had a significant impact on the dispersion state of SPI/BT mixtures in aquesous solution. At low SPI concentrations, strong aggregations were created, resulting in the formation of thick, loose, high-porosity and high-permeability filter cakes and high fluid loss. At high SPI concentrations, intercatlated/exfoliated structures were generated, resulting in the formation of thin, compact, low-porosity and low-permeability filter cakes and low fluid loss. The SPI/BT-WDFs exhibited superior filtration property than pure BT-WDFs at the same solid concentraion, demonstrating the potential utilization of SPI as an effective, renewable, and biodegradable fluid loss reducer in well excavation applications.

  18. Parametric Optimization of Organic Rankine Cycle with R245fa/R601a as Working Fluid

    Institute of Scientific and Technical Information of China (English)

    Zhu Jialing; Kang Zhenhua; An Qingsong; Li Tailu

    2015-01-01

    In order to select the appropriate working fluids and optimize parameters for medium-temperature geothermally-powered organic Rankine cycle(ORC), R245fa is mixed with R601a atgeothermal water temperature of 110℃. Based on thermodynamics, the characteristics of mixture and its influence on the performance of ORC under different evaporating temperatures and composition proportionsare analyzed. Results show that the zeotropic mixture R245fa/R601a(0.4/0.6) has the highest performance. When the evaporating temperature reaches 67℃, the outlet temperature of geothermal water is 61℃, the net power output is the highest and the thermal efficiency is about 9%.

  19. 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.

  20. 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.

  1. A magnetorheological fluid based orthopedic active knee brace

    Science.gov (United States)

    Zite, Jamaal L.; Ahmadkhanlou, Farzad; Neelakantan, Vijay A.; Washington, Gregory N.

    2006-03-01

    The disadvantage of current knee braces ranges from high cost for customization to a loss in physical mobility and limited rehabilitative value. One approach to solving this problem is to use a Magnetorheological (MR) device to make the knee brace have a controllable resistance. Our design solution is to replace the manufacturer's joint with an rotary MR fluid based shear damper. The device is designed based on a maximum yield stress, a corresponding magnetic field, a torque and the MR fluid viscosity. The analytical and experimental results show the advantages and the feasibility of using the proposed MR based controllable knee braces.

  2. 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.

  3. Multiscale Turbulence Models Based on Convected Fluid Microstructure

    CERN Document Server

    Holm, Darryl D

    2012-01-01

    The Euler-Poincar\\'e approach to complex fluids is used to derive multiscale equations for computationally modelling Euler flows as a basis for modelling turbulence. The model is based on a \\emph{kinematic sweeping ansatz} (KSA) which assumes that the mean fluid flow serves as a Lagrangian frame of motion for the fluctuation dynamics. Thus, we regard the motion of a fluid parcel on the computationally resolvable length scales as a moving Lagrange coordinate for the fluctuating (zero-mean) motion of fluid parcels at the unresolved scales. Even in the simplest 2-scale version on which we concentrate here, the contributions of the fluctuating motion under the KSA to the mean motion yields a system of equations that extends known results and appears to be suitable for modelling nonlinear backscatter (energy transfer from smaller to larger scales) in turbulence using multiscale methods.

  4. Selecting the process arrangement for preparing the gas turbine working fluid for an integrated gasification combined-cycle power plant

    Science.gov (United States)

    Ryzhkov, A. F.; Gordeev, S. I.; Bogatova, T. F.

    2015-11-01

    Introduction of a combined-cycle technology based on fuel gasification integrated in the process cycle (commonly known as integrated gasification combined cycle technology) is among avenues of development activities aimed at achieving more efficient operation of coal-fired power units at thermal power plants. The introduction of this technology is presently facing the following difficulties: IGCC installations are characterized by high capital intensity, low energy efficiency, and insufficient reliability and availability indicators. It was revealed from an analysis of literature sources that these drawbacks are typical for the gas turbine working fluid preparation system, the main component of which is a gasification plant. Different methods for improving the gasification plant chemical efficiency were compared, including blast air high-temperature heating, use of industrial oxygen, and a combination of these two methods implying limited use of oxygen and moderate heating of blast air. Calculated investigations aimed at estimating the influence of methods for achieving more efficient air gasification are carried out taking as an example the gasifier produced by the Mitsubishi Heavy Industries (MHI) with a thermal capacity of 500 MW. The investigation procedure was verified against the known experimental data. Modes have been determined in which the use of high-temperature heating of blast air for gasification and cycle air upstream of the gas turbine combustion chamber makes it possible to increase the working fluid preparation system efficiency to a level exceeding the efficiency of the oxygen process performed according to the Shell technology. For the gasification plant's configuration and the GTU working fluid preparation system be selected on a well-grounded basis, this work should be supplemented with technical-economic calculations.

  5. 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.

  6. 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.

  7. Efficiency Of Rankine Cycle And Optimum Working Fluid Using Redlich-Kwong Equation Of State

    Science.gov (United States)

    Saunderson, Deborah; Budiman, R. Arief

    2010-10-01

    Efficiency of Rankine cycle as a function of working fluid molecule is modeled using the Redlich-Kwong equation of state. We have evaluated 12 molecules, ranging from water to ethylene glycol, and have parameterized their individual performance on several material parameters, including heat capacity and compressibility. This research aims to understand at the molecular level what drives some molecules to perform better at certain temperature and pressure range of the Rankine cycle. Immediate applications we are interested in are geothermal power and solar thermal energy conversion.

  8. Optimum Working Fluid Selection For Rankine Cycle Using Redlich-Kwong Equation of State

    Science.gov (United States)

    Budiman, Arief; Saunderson, Deborah

    2011-03-01

    Efficiency of Rankine cycle as a function of working fluid molecule is modeled using Redlich-Kwong equation of state. We have evaluated 12 molecules, ranging from water to ethylene glycol, and have parameterized their individual performance on several material parameters, including heat capacity and compressibility. This research aims to understand at the molecular level what drives some molecules to perform better at certain temperature and pressure range of the Rankine cycle. Immediate applications we are interested in are geothermal power, solar thermal energy conversion and waste heat recovery.

  9. 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.

  10. Thermodynamic Cycles using Carbon Dioxide as Working Fluid : CO2 transcritical power cycle study

    OpenAIRE

    Yang, Chen

    2011-01-01

    The interest in utilizing the energy in low‐grade heat sources and waste heat is increasing. There is an abundance of such heat sources, but their utilization today is insufficient, mainly due to the limitations of the conventional power cycles in such applications, such as low efficiency, bulky size or moisture at the expansion outlet (e.g. problems for turbine blades). Carbon dioxide (CO2) has been widely investigated for use as a working fluid in refrigeration cycles, because it has no ozo...

  11. Computer fluid dynamics (CFD) study of a plate heat exchanger working with nanofluids

    Science.gov (United States)

    Stan, Liviu-Constantin; Cǎlimǎnescu, Ioan

    2016-12-01

    The industry fosters many types of heat exchangers such double pipe or plate heat exchangers (HX), but lately the plate HX are gaining the high ground in many applications. Such a plate HX is made out of serial plate modules packed together allowing the warm and cold fluids to pass through and exchange the heat. The paper is demonstrating the functioning of a medium sized plate HX functioning with 10% Al2O3 and water nanofluids flowing in both cold and warm sides of the HX. The influence of the nanofluid properties will be investigated as impact upon the outlet temperature of the fluid leaving the HX. Using the RSM methodology. The main conclusion of this study is that there is a balance between the nanofluids increased conductivity and their increased viscosity. The nanofluids are working well for those applications where the flow is not impeded by narrow fluid passages where the bigger influence of the viscosity is actually worsening the heat transfer conditions instead of increasing it, since the influence of viscosity in that kind of applications is three time bigger. A nanofluid conductivity threshold was also detected over which the nanofluids say with 15$ or 20% alumina content is useless for the overall heat transfer conditions.

  12. 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).

  13. 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...

  14. Preparation and electrical properties of oil-based magnetic fluids

    Science.gov (United States)

    Sartoratto, P. P. C.; Neto, A. V. S.; Lima, E. C. D.; Rodrigues de Sá, A. L. C.; Morais, P. C.

    2005-05-01

    This paper describes an improvement in the preparation of magnetic fluids for electrical transformers. The samples are based on surface-coated maghemite nanoparticles dispersed in transformer insulating oil. Colloidal stability at 90°C was higher for oleate-grafted maghemite-based magnetic fluid, whereas decanoate and dodecanoate-grafted samples were very unstable. Electrical properties were evaluated for samples containing 0.80%-0.0040% maghemite volume fractions. Relative permittivity varied from 8.8 to 2.1 and the minimum value of the loss factor was 12% for the most diluted sample. The resistivity falls in the range of 0.7-2.5×1010Ωm, whereas the ac dielectric strength varied from 70to79kV. These physical characteristics reveal remarkable step forward in the properties of the magnetic fluid samples and may result in better operation of electrical transformers.

  15. 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.

  16. Wave front distortion based fluid flow imaging

    Science.gov (United States)

    Iffa, Emishaw; Heidrich, Wolfgang

    2013-03-01

    In this paper, a transparent flow surface reconstruction based on wave front distortion is investigated. A camera lens is used to focus the image formed by the micro-lens array to the camera imaging plane. The irradiance of the captured image is transformed to frequency spectrum and then the x and y spatial components are separated. A rigid spatial translation followed by low pass filtering yields a single frequency component of the image intensity. Index of refraction is estimated from the inverse Fourier transform of the spatial frequency spectrum of the irradiance. The proposed method is evaluated with synthetic data of a randomly generated index of refraction value and used to visualize a fuel injection volumetric data.

  17. Overview of Ionic Liquids Used as Working Fluids in Absorption Cycles

    Directory of Open Access Journals (Sweden)

    Mehrdad Khamooshi

    2013-01-01

    Full Text Available The cycle performance of refrigeration cycles depends not only on their configuration, but also on thermodynamic properties of working pairs regularly composed of refrigerant and absorbent. The commonly used working pairs in absorption cycles are aqueous solutions of either lithium bromide water or ammonia water. However, corrosion, crystallization, high working pressure, and toxicity are their major disadvantages in industrial applications. Therefore, seeking more advantageous working pairs with good thermal stability, with minimum corrosion, and without crystallization has become the research focus in the past two decades. Ionic liquids (ILs are room-temperature melting salts that can remain in the liquid state at near or below room temperature. ILs have attracted considerable attention due to their unique properties, such as negligible vapor pressure, nonflammability, thermal stability, good solubility, low melting points, and staying in the liquid state over a wide temperature range from room temperature to about 300°C. The previously mentioned highly favorable properties of ILs motivated us for carrying out the present research and reviewing the available ILs found in the literature as the working fluids of absorption cycles. Absorption cycles contain absorption heat pumps, absorption chillers, and absorption transformers.

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

    OpenAIRE

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    2015-01-01

    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 assessment of novel working fluids relies on accurate property data. Flammability data like the lower and upper flammability limit (LFL and UFL) play an important role in quantifying the risk of fire and e...

  19. 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.

  20. Mineralizing conditions and source fluid composition of base metal sulfides in the Lon District, southeastern Iceland

    Science.gov (United States)

    Kremer, C. H.; Thomas, D.; García del Real, P.; Zierenberg, R. A.; Bird, D. K.

    2014-12-01

    Hydrothermal base metal mineralization is rare in Iceland due to the scarcity of evolved magma bodies that discharge metal-rich aqueous fluids into bedrock. One exception is the Lon District of southeastern Iceland, where explosively emplaced rhyolitic breccias host base metal sulfide minerals. We performed petrographic, fluid inclusion, and stable isotope analyses on samples collected in Lon to constrain the conditions of sulfide mineral formation. Based on outcrop and hand sample observations, hot, early-stage hydrothermal fluids precipitated sulfide minerals, quartz, and epidote in rhyolitic breccia and basalt flows. Cooler late-stage fluids precipitated carbonates and quartz in rhyolitic breccia and basalt flows. The order of precipitation of the sulfides was: galena, sphalerite, then chalcopyrite. Homogenization temperatures of liquid-dominated multi-phase fluid inclusions in hydrothermal early-stage quartz coeval with chalcopyrite cluster around 303 °C and 330 °C, indicating precipitation of metallic sulfides in two main hydrothermal fluid pulses early in the period of hydrothermal activity in the Lon District. Freezing point depression analyses of fluid inclusions in quartz show that the sulfide minerals precipitated from a solution that was 4 wt. % NaCl. The 𝛿34S values of sulfides indicate that early-stage hydrothermal sulfur was derived from igneous rocks, either through leaching by non-magmatic hydrothermal fluids or by exsolution of magmatic waters. Early stage epidote 𝛿D values were on average -65.96 per mil, about 14 per mil higher than reported values in epidotes from elsewhere in southeastern Iceland. The 𝛿13C and 𝛿18O values of late-stage carbonates indicate that late stage hydrothermal fluids were meteoric in origin. Collectively, fluid inclusion and stable isotope analyses suggest that early-stage aqueous fluids derived from a mixture of magmatic waters exsolved from the proximal Geitafell intrusion and meteoric

  1. Optimization-based Fluid Simulation on Unstructured Meshes

    DEFF Research Database (Denmark)

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

    We present a novel approach to fluid simulation, allowing us to take into account the surface energy in a pre- cise manner. This new approach combines a novel, topology-adaptive approach to deformable interface track- ing, called the deformable simplicial complexes method (DSC) with an optimization......-based, linear finite element method for solving the incompressible Euler equations. The deformable simplicial complexes track the surface of the fluid: the fluid-air interface is represented explicitly as a piecewise linear surface which is a subset of tetra- hedralization of the space, such that the interface...... can be also represented implicitly as a set of faces separating tetrahedra marked as inside from the ones marked as outside. This representation introduces insignificant and con- trollable numerical diffusion, allows robust topological adaptivity and provides both a volumetric finite element mesh...

  2. Characteristic analysis of magnetorheological fluid based on different carriers

    Institute of Scientific and Technical Information of China (English)

    张建; 张进秋; 贾进峰

    2008-01-01

    In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45# transformer oil,was finished.And characteristics of these samples were tested and analyzed.The results show that Tween-80 and Span-80 can improve the sedimentary stability,and the larger mass fraction can also increase the sedimentary stability.Using 45# transformer oil instead of special shock absorption fluid as a carrier of MRF,the shear yield stress remains nearly constant but the viscosity and the sedimentary stability are reduced.The MRF with diameter of 2.73 μm shows better sedimentary stability than that of the MRF with diameter of 2.30 μm,or 4.02 μm.Stearic acid obviously improves sedimentary stability and off-state viscosity,but has no function on the shear yield stress.In magnetic field of 237 kA/m,the shear yield stress of MRF based on special shock absorption fluid is 18.34 kPa and the shear yield stress of MRF based on 45# transformer oil is 14.26 kPa.

  3. 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

    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...... technical tool to convert this waste heat into usable energy. So far the low-temperature heat cannot be utilized efficiently for electricity generation.In order to optimize the heat transfer process and the power generation, the influence of the working fluid, the cycledesigns and the operating conditions...... 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...

  4. 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.

  5. Numerical simulation of fluid bed drying based on two-fluid model and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Assari, M.R. [Jundi-shapur University, Dezful (Iran); Basirat Tabrizi, H.; Saffar-Avval, M. [Amirkabir University of Technology, Department of Mechanical Engineering, Tehran (Iran)

    2007-02-15

    A mathematical model for batch drying based on the Eulerian 'two-fluid models' was developed. The two-dimensional, axis-symmetrical cylindrical equations for both phases were solved numerically. The governing equations were discretized using a finite volume method with local grid refinement near the wall and inlet port. The effects of parameters such as inlet gas velocity and inlet gas temperature on the moisture content, temperature of solid and gas at the outlet are shown. This data from the model was compared with that obtained from experiments with a fluidized bed and found to be in reasonably good agreement. (author)

  6. 40 CFR Appendix 3 to Subpart A of... - Procedure for Mixing Base Fluids With Sediments

    Science.gov (United States)

    2010-07-01

    ...) sediments with the base fluids that are used to formulate synthetic-based drilling fluids and other non-aqueous drilling fluids. Initially, control sediments shall be press-sieved through a 2000 micron mesh... fluids (e.g., whole mud formulations), determine the spike amount as follows: × × = Test...

  7. 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.

  8. 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%.

  9. 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.

  10. Lupus and community-based social work.

    Science.gov (United States)

    Schudrich, Wendy; Gross, Diane; Rowshandel, Jessica

    2012-01-01

    Systemic lupus erythematous (SLE) is a chronic autoimmune disease that disproportionately strikes women of color. SLE patients frequently experience physical, emotional, and social challenges that often result in unmet biopsychosocial needs. Because of the nature of the disease and the needs of patients, agencies serving SLE patients that engage in community-based social work can positively impact their clients' lives. The S.L.E. Lupus Foundation participates in a myriad of community-based social work practices to help address the needs of their clients. These services include helping economically disadvantaged patients access appropriate services within their communities, building awareness about SLE in society, connecting with government officials at all levels, and collaborating with health care organizations to serve those affected by SLE. Specific examples of community-based activities at the S.L.E. Lupus Foundation are described in detail.

  11. A magnetorheological fluid-based controllable active knee brace

    Science.gov (United States)

    Ahmadkhanlou, Farzad; Zite, Jamaal L.; Washington, Gregory N.

    2007-04-01

    High customization costs and reduction of natural mobility put current rehabilitative knee braces at a disadvantage. A resolution to this problem is to integrate a Magnetorheological (MR) fluid-based joint into the system. A MR joint will allow patients to apply and control a resistive torque to knee flexion and extension. The resistance torque can also be continuously adjusted as a function of extension angle and patient strength (or as a function of time), which is currently impossible with state of the art rehabilitative knee braces. A novel MR fluid-based controllable knee brace is designed and prototyped in this research. The device exhibits large resistive torque in the on-state and low resistance in the offstate. The controllable variable stiffness, compactness, and portability of the system make it a proper alternative to current rehabilitative knee braces.

  12. Rheological Properties Of Some Surfactant-Based Fracturing Fluids

    Directory of Open Access Journals (Sweden)

    Andra Tamas

    2014-02-01

    Full Text Available The paper presents the rheological behavior study of some cationic surfactant-based aqueous solutions that can be used as fracturing fluids. It was followed the influence of salt type and concentration, as well as that of temperature by setting the dependence between the shear stress τ and the shear rate   . The analysis of dependence between τ and   demonstrates that all the studied solutions have non-Newtonian behavior with flow behavior index smaller than 1.

  13. Vibration control of flexible structures via electrorheological-fluid-based dampers

    Science.gov (United States)

    Wang, Kon-Well; Kim, Y. S.; Lee, H. S.; Shea, D. B.

    1993-09-01

    The semi-active control approach has been recognized to be effective for vibration suppression of flexible structures. The electrorheological (ER) fluid-based device is a good candidate for such applications. In this research, a new control law is developed to maximize the damping effect of ER dampers for structural vibration suppression under actuator constraints and viscous-frictional-combined damping. Both numerical simulations and experimental work have been carried out to evaluate and validate the theoretical predictions.

  14. 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.

  15. 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

    assessment of novel working fluids relies on accurate property data. Flammability data like the lower and upper flammability limit (LFL and UFL) play an important role in quantifying the risk of fire and explosion. For novel working fluid candidates experimental values are not available for the safety...... analysis. In this case property prediction models like group contribution (GC) models can estimate flammability data. The estimation needs to be accurate, reliable and as less time consuming as possible [1]. However, GC property prediction methods frequently lack rigorous uncertainty analysis. Hence...

  16. Preliminary Experimental Investigation on MHD Power Generation Using Seeded Supersonic Argon Flow as Working Fluid

    Institute of Scientific and Technical Information of China (English)

    LI Yiwen; LI Yinghong; LU Haoyu; ZHU Tao; ZHANG Bailing; CHEN Feng; ZHAO Xiaohu

    2011-01-01

    This paper presents a preliminary experimental investigation on magnetohydrodynamic (MHD) power generation using seeded supersonic argon flow as working fluid.Helium and argon are used as driver and driven gas respectively in a shock tunnel.Equilibrium contact surface operating mode is used to obtain high temperature gas,and the conductivity is obtained by adding seed K2CO3 powder into the driven section.Under the conditions of nozzle inlet total pressure being 0.32 MPa,total temperature 6 504 K,magnetic field density about 0.5 T and nozzle outlet velocity 1 959 m/s,induction voltage and short-circuit current of the segmentation MHD power generation channel are measured,and the experimental results agree with theoretical calculations; the average conductivity is about 20 S/m calculated from characteristics of voltage and current.When load factor is 0.5,the maximum power density of the MHD power generation channel reaches 4.797 1 MW/m3,and the maximum enthalpy extraction rate is 0.34%.Finally,the principle and method of indirect testing for gas state parameters are derived and analyzed.

  17. 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.

  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. Replacement of petroleum based hydraulic fluids with a soybean-based alternative

    Energy Technology Data Exchange (ETDEWEB)

    Rose, B.; Rivera, P.

    1998-05-01

    Despite the best preventative measures, ruptured hoses, spills and leaks occur with use of all hydraulic equipment. Although these releases do not usually produce a RCRA regulated waste, they are often a reportable occurrence. Clean-up and subsequent administrative procedure involves additional costs, labor and work delays. Concerns over these releases, especially related to Sandia National Laboratories (SNL) vehicles hauling waste on public roads prompted Fleet Services (FS) to seek an alternative to the standard petroleum based hydraulic fluid. Since 1996 SNL has participated in a pilot program with the University of Iowa (UNI) and selected vehicle manufacturers, notably John Deere, to field test hydraulic fluid produced from soybean oil in twenty of its vehicles. The vehicles included loaders, graders, sweepers, forklifts and garbage trucks. Research was conducted for several years at UNI to modify and market soybean oils for industrial uses. Soybean oil ranks first in worldwide production of vegetable oils (29%), and represents a tremendous renewable resource. Initial tests with soybean oil showed excellent lubrication and wear protection properties. Lack of oxidative stability and polymerization of the oil were concerns. These concerns were being addressed through genetic alteration, chemical modification and use of various additives, and the improved lubricant is in the field testing stage.

  20. Application of Ester based Drilling Fluid for Shale Gas Drilling

    Science.gov (United States)

    Sauki, Arina; Safwan Zazarli Shah, Mohamad; Bakar, Wan Zairani Wan

    2015-05-01

    Water based mud is the most commonly used mud in drilling operation. However, it is ineffective when dealing with water-sensitive shale that can lead to shale hydration, consequently wellbore instability is compromised. The alternative way to deal with this kind of shale is using synthetic-based mud (SBM) or oil-based mud (OBM). OBM is the best option in terms of technical requirement. Nevertheless, it is toxic and will create environmental problems when it is discharged to onshore or offshore environment. SBM is safer than the OBM. The aim of this research is to formulate a drilling mud system that can carry out its essential functions for shale gas drilling to avoid borehole instability. Ester based SBM has been chosen for the mud formulation. The ester used is methyl-ester C12-C14 derived from palm oil. The best formulation of ester-based drilling fluid was selected by manipulating the oil-water ratio content in the mud which are 70/30, 80/20 and 90/10 respectively. The feasibility of using this mud for shale gas drilling was investigated by measuring the rheological properties, shale reactivity and toxicity of the mud and the results were compared with a few types of OBM and WBM. The best rheological performance can be seen at 80/20 oil-water ratio of ester based mud. The findings revealed that the rheological performance of ester based mud is comparable with the excellent performance of sarapar based OBM and about 80% better than the WBM in terms of fluid loss. Apart from that, it is less toxic than other types of OBM which can maintain 60% prawn's survival even after 96 hours exposure in 100,000 ppm of mud concentration in artificial seawater.

  1. Systematic Methods for Working Fluid Selection and the Design, Integration and Control of Organic Rankine Cycles—A Review

    Directory of Open Access Journals (Sweden)

    Patrick Linke

    2015-05-01

    Full Text Available Efficient power generation from low to medium grade heat is an important challenge to be addressed to ensure a sustainable energy future. Organic Rankine Cycles (ORCs constitute an important enabling technology and their research and development has emerged as a very active research field over the past decade. Particular focus areas include working fluid selection and cycle design to achieve efficient heat to power conversions for diverse hot fluid streams associated with geothermal, solar or waste heat sources. Recently, a number of approaches have been developed that address the systematic selection of efficient working fluids as well as the design, integration and control of ORCs. This paper presents a review of emerging approaches with a particular emphasis on computer-aided design methods.

  2. Influenza A Virus Surveillance Based on Pre-Weaning Piglet Oral Fluid Samples.

    Science.gov (United States)

    Panyasing, Y; Goodell, C; Kittawornrat, A; Wang, C; Levis, I; Desfresne, L; Rauh, R; Gauger, P C; Zhang, J; Lin, X; Azeem, S; Ghorbani-Nezami, S; Yoon, K-J; Zimmerman, J

    2016-10-01

    Influenza A virus (IAV) surveillance using pre-weaning oral fluid samples from litters of piglets was evaluated in four ˜12 500 sow and IAV-vaccinated, breeding herds. Oral fluid samples were collected from 600 litters and serum samples from their dams at weaning. Litter oral fluid samples were tested for IAV by virus isolation, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), RT-PCR subtyping and sequencing. Commercial nucleoprotein (NP) enzyme-linked immunosorbent assay (ELISA) kits and NP isotype-specific assays (IgM, IgA and IgG) were used to characterize NP antibody in litter oral fluid and sow serum. All litter oral fluid specimens (n = 600) were negative by virus isolation. Twenty-five oral fluid samples (25/600 = 4.2%) were qRT-PCR positive based on screening (Laboratory 1) and confirmatory testing (Laboratory 2). No hemagglutinin (HA) and neuraminidase (NA) gene sequences were obtained, but matrix (M) gene sequences were obtained for all qRT-PCR-positive samples submitted for sequencing (n = 18). Genetic analysis revealed that all M genes sequences were identical (GenBank accession no. KF487544) and belonged to the triple reassortant influenza A virus M gene (TRIG M) previously identified in swine. The proportion of IgM- and IgA-positive samples was significantly higher in sow serum and litter oral fluid samples, respectively (P oral fluids. This study supported the use of oral fluid sampling as a means of conducting IAV surveillance in pig populations and demonstrated the inapparent circulation of IAV in piglets. Future work on IAV oral fluid diagnostics should focus on improved procedures for virus isolation, subtyping and sequencing of HA and NA genes. The role of antibody in IAV surveillance remains to be elucidated, but longitudinal assessment of specific antibody has the potential to provide information regarding patterns of infection, vaccination status and herd immunity.

  3. River Network Evolution Based on Fluid-Erosion Model

    OpenAIRE

    2010-01-01

    A new landscape evolution model is proposed which is composed of the shallow water equations for the fluid above the sediment and the mass conservation equation of the sediment. Numerical simulations of the formation of landscape and river network are carried out based on these equations. It is shown that steady patterns of river network are formed for the initial inclinations of slopes within 0.00005 and 0.005. The fractal dimensions of the river network and the exponent of Hack's law are ob...

  4. 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

    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...

  5. 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.

  6. A portable electronic system for in-situ measurements of oil concentration in MetalWorking fluids

    CERN Document Server

    Grossi, M

    2016-01-01

    MetalWorking Fluids (MWFs) are widely used to cool and lubricate machines and tools. By far, the most common MWFs are oil-in-water emulsions with oil concentration (C oil) in the range from 1% to 10%, depending on type of oil, material to be worked, etc. In order to optimize emulsion and machine performance, as well as for good waste policy, the right value of C oil should be kept (approximately) constant during the MWF's lifecycle to compensate inevitable changes due to water evaporation, bacterial attack, oil adhesion to metal parts, etc.. This, however, requires periodic measurements, often skipped because they require unhandy operations and produce inaccurate results. In this context, a new system is presented that is based on the falling ball principle, normally used for viscosity measurements, shown to be suitable also for accurate C oil measurements. In our system, the transit time of the sphere within the instrument is determined by means of inductive proximity sensors, a PT100 sensor is used for temp...

  7. Current development of saliva/oral fluid-based diagnostics.

    Science.gov (United States)

    Yeh, Chih-Ko; Christodoulides, Nicolaos J; Floriano, Pierre N; Miller, Craig S; Ebersole, Jeffrey L; Weigum, Shannon E; McDevitt, John; Redding, Spencer W

    2010-07-01

    Saliva can be easily obtained in medical and non-medical settings, and contains numerous bio-molecules, including those typically found in serum for disease detection and monitoring. In the past two decades, the achievements of high-throughput approaches afforded by biotechnology and nanotechnology allow for disease-specific salivary biomarker discovery and establishment of rapid, multiplex, and miniaturized analytical assays. These developments have dramatically advanced saliva-based diagnostics. In this review, we discuss the current consensus on development of saliva/oral fluid-based diagnostics and provide a summary of recent research advancements of the Texas-Kentucky Saliva Diagnostics Consortium. In the foreseeable future, current research on saliva based diagnostic methods could revolutionize health care.

  8. Two-Phase Working Fluids for the Temperature Range 50 to 350 C

    Science.gov (United States)

    Saaski, E. W.; Owzarski, P. C.

    1977-01-01

    The decomposition and corrosion of two-phase heat transfer liquids and metal envelopes have been investigated on the basis of molecular bond strengths and chemical thermodynamics. Potentially stable heat transfer fluids for the temperature range 100 C to 350 C have been identified, and reflux heat pipes tests initiated with 10 fluids and carbon steel and aluminum envelopes to experimentally establish corrosion behavior and noncondensable gas generation rates.

  9. Effects of Working Fluid,Tubeside Enhancement and Bundle Depth on the Optimized Fin Geometry of a Horizontal Condenser Tube

    Institute of Scientific and Technical Information of China (English)

    H.Honda; T.Fukuda

    1992-01-01

    A theoretical study has been made to optimize the fin geometry of a horizontal finned tube which is to be used for condensers that handle the vapor load of a liquid phase change cooling module,Systematic numerical calculations of the vapor to coolant heat transfer coefficinet.Three dielctric fluids(R-113,FC-72,and FC-87) at atmospheric pressure were selected as the working fluids.For a single tube with optimized fin geometry,the average heat flux increased in the order of FC-87,R-113 and FC-72.Both the optimum fin height and optimum fin spacing incresaed with increasing vertical bundle depth.

  10. 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

    the irreversibility in the ORC system. This work considers mixtures of R245fa/pentane and propane/isobutane. The use of multi-component working fluids typically results in increased heat transfer areas and different expander designs compared to purefluids. In order to properly account for turbine performance...... 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...

  11. A three-stage Stirling pulse tube cryocooler reached 4.26 K with He-4 working fluid

    Science.gov (United States)

    Zhi, X. Q.; Han, L.; Dietrich, M.; Gan, Z. H.; Qiu, L. M.; Thummes, G.

    2013-12-01

    Multi-stage Stirling pulse tube cryocoolers (SPTCs) working at liquid helium temperatures are attractive because of their promising potential in tactical and space applications. However, it is still a challenge for a SPTC to operate below 5 K with He-4 as working fluid instead of the rare He-3. In this study, the operating characteristics of an in-house made three-stage SPTC were experimentally investigated. The mutual influence of precooling temperature, operating frequency, input power, and charge pressure on the cooling performance of the third stage was studied. A no-load temperature of 4.26 K was achieved by the three-stage SPTC, which is the lowest temperature ever obtained by a multi-stage SPTC operating with He-4 as working fluid.

  12. A new measuring method to detect the emissions of metal working fluid mist.

    Science.gov (United States)

    Wlaschitz, Peter; Höflinger, Wilhelm

    2007-06-18

    During metal machining the rotating machine tool or grinding wheel is generating fine droplets and vapor which can cause occupational health problems. A new continuous measuring method was developed to detect both droplets and vapor of metalworking fluid mist and to provide information about the droplet size distribution. According to this method, an air sample of the metalworking fluid mist is segregated by impactors of different cut sizes, carried out in several successive passes. In each pass the droplets that are not collected in the impactor are fed into an evaporator that immediately evaporates all droplets, and subsequently the sample is analyzed in-line by a Flame Ionization Detector (FID). By subtraction of the value measured at the respectively next smaller fraction, the oil amount of the metalworking fluid mist found in a certain droplet size range is obtained. The metalworking fluid mist is thus segregated according to the droplet size, and a definite cut size between droplet and vapor can be defined, below which we can say "vapor". This method was calibrated with Di-2-Ethylhexyl-Sebacat (DEHS) as equivalence substance for further measurements applied on various metalworking fluids.

  13. [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.

  14. 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.

  15. 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.

  16. 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.)

  17. 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)

  18. 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.

  19. 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.

  20. Fluid-structural dynamics of ground-based and microgravity caloric tests

    Science.gov (United States)

    Kassemi, M.; Oas, J. G.; Deserranno, Dimitri

    2005-01-01

    Microgravity caloric tests aboard the 1983 SpaceLab1 mission produced nystagmus results with an intensity comparable to those elicited during post- and pre- flight tests, thus contradicting the basic premise of Barany's convection hypothesis for caloric stimulation. In this work, we present a dynamic fluid structural analysis of the caloric stimulation of the lateral semicircular canal based on two simultaneous driving forces for the endolymphatic flow: natural convection driven by the temperature-dependent density variation in the bulk fluid and expansive convection caused by direct volumetric displacement of the endolymph during the thermal irrigation. Direct numerical simulations indicate that on earth, the natural convection mechanism is dominant. But in the microgravity environment of orbiting spacecraft, where buoyancy effects are mitigated, expansive convection becomes the sole mechanism for producing cupular displacement. A series of transient 1 g and microgravity case studies are presented to delineate the differences between the dynamics of the 1 g and microgravity endolymphatic flows. The impact of these different flow dynamics on the endolymph-cupula fluid-structural interactions is also analyzed based on the time evolutions of cupular displacement and velocity and the transcupular pressure differences.

  1. 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.

  2. Capacity, Control, or Both – Which Aspects of Working Memory Contribute to Children’s General Fluid Intelligence?

    Directory of Open Access Journals (Sweden)

    Nęcka Edward

    2016-04-01

    Full Text Available Starting from the assumption that working memory capacity is an important predictor of general fluid intelligence, we asked which aspects of working memory account for this relationship. Two theoretical stances are discussed. The first one posits that the important explanatory factor is storage capacity, roughly defined as the number of chunks possible to hold in the focus of attention. The second one claims that intelligence is explained by the efficiency of executive control, for instance, by prepotent response inhibition. We investigated 96 children at the age between 10 and 13. They completed a version of the n-back task that allows assessment of both storage capacity and inhibitory control. They also completed Raven’s Progressive Matrices as the fluid intelligence test and the Test for Creative Thinking - Drawing Production, for control purposes. We found that Raven’s scores correlated negatively with the number of unnecessary responses to irrelevant stimuli but they did not correlate with the number of signal detections. We conclude that children’s fluid intelligence depends on inhibitory control, with no relationship with storage capacity.

  3. Synthesis and Performance Evaluation of a New Deoiling Agent for Treatment of Waste Oil-Based Drilling Fluids

    Directory of Open Access Journals (Sweden)

    Pingting Liu

    2014-01-01

    Full Text Available Oil-based drilling fluid is used more and more in the field of oil and gas exploration. However, because of unrecyclable treating agent and hard treatment conditions, the traditional treating technologies of waste oil-based drilling fluid have some defects, such as waste of resource, bulky equipment, complex treatment processes, and low oil recovery rate. In this work, switchable deoiling agent (SDA, as a novel surfactant for treatment of waste oil-based drilling fluid, was synthesized by amine, formic acid, and formaldehyde solution. With this agent, the waste oil-based drilling fluid can be treated without complex process and expensive equipment. Furthermore, the agent used in the treatment can be recycled, which reduces waste of resource and energy. The switch performance, deoiling performance, structural characterization, and mechanisms of action are studied. The experimental results show that the oil content of the recycled oil is higher than 96% and more than 93% oil in waste oil-based drilling fluid can be recycled. The oil content of the solid residues of deoiling is less than 3%.

  4. Teaching Standards-Based Group Work Competencies to Social Work Students: An Empirical Examination

    Science.gov (United States)

    Macgowan, Mark J.; Vakharia, Sheila P.

    2012-01-01

    Objectives: Accreditation standards and challenges in group work education require competency-based approaches in teaching social work with groups. The Association for the Advancement of Social Work with Groups developed Standards for Social Work Practice with Groups, which serve as foundation competencies for professional practice. However, there…

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

    OpenAIRE

    Zhanar Nurakhmetova; Iskander Gussenov; Vladimir Sigitov; Sarkyt Kudaibergenov

    2016-01-01

    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 b...

  6. Applications of laser based measurements to combustion related fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Klingmann, J.

    1998-12-01

    This thesis is concerned with laser based techniques for the measurement of fluid dynamical properties and their application to combusting flow fields or flow fields related to combustion. As an introduction, the theory of turbulent flow and combustion is shortly presented. An overview of laser based measuring techniques is given. Next, seven papers are included. The main topic of papers 1 and 2 is the measurements of swirling pipe flows with sudden axi-symmetric expansions. These flow fields are related to the flow fields of gas turbine combustors. Measurements and computations using commercial software are compared. Papers 3 and 7 deal with a laser Doppler anemometry based method for the measurement of the turbulent dissipation rate and its application to an axi-symmetric free jet, respectively. The measurements rely on two-point measurements with high spatial resolution. Also three-component one-point measurements are used to obtain the triple velocity correlations. Together these measurements are sufficient to present the energy balance, if pressure effects are neglected. Papers 4, 5 and 6 are concerned with the turbulent flame speed under premixed conditions. Papers 4 and 5 present flame speed measurements from a stationary burner using methane and Danish natural gas. Particle image velocimetry and one- and two-point Laser Doppler anemometry is used to measure flame speed and turbulent quantities, including integral length scales. Paper 7 presents measurements of flame speed and turbulence parameters in a spark ignition engine. Here heat release analyses from pressure measurements are combined with one- and two-point laser Doppler anemometry to analyze influence of turbulence on flame propagation 50 refs, 25 figs

  7. 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).

  8. Writing Assignments Based on Literary Works.

    Science.gov (United States)

    Matthews, Dorothy, Ed.

    1985-01-01

    The literature selections serving as the basis for writing assignments in the articles in this journal issue range from time-honored English classics ("Beowulf,""Sir Gawain and the Green Knight") and American standards ("A Farewell to Arms,""The Scarlet Letter") to contemporary fiction. The articles deal with works by women writers (Shirley…

  9. 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…

  10. Deforming fluid domains within the finite element method: Five mesh-based tracking methods in comparison

    CERN Document Server

    Elgeti, Stefanie

    2015-01-01

    Fluid flow applications can involve a number of coupled problems. One is the simulation of free-surface flows, which require the solution of a free-boundary problem. Within this problem, the governing equations of fluid flow are coupled with a domain deformation approach. This work reviews five of those approaches: interface tracking using a boundary-conforming mesh and, in the interface capturing context, the level-set method, the volume-of-fluid method, particle methods, as well as the phase-field method. The history of each method is presented in combination with the most recent developments in the field. Particularly, the topics of extended finite elements (XFEM) and NURBS-based methods, such as Isogeometric Analysis (IGA), are addressed. For illustration purposes, two applications have been chosen: two-phase flow involving drops or bubbles and sloshing tanks. The challenges of these applications, such as the geometrically correct representation of the free surface or the incorporation of surface tension ...

  11. Teaching Is ... Opening up Spaces to Explore Academic Work in Fluid and Volatile Times

    Science.gov (United States)

    Sadler, Kirsten; Selkrig, Mark; Manathunga, Catherine

    2017-01-01

    Universities are built upon the collaborative work of academic staff and students, yet the nature of this work has been undergoing profound and rapid change. Pressures within Australia's higher education sector have led to a fracturing of traditional academic roles and growing feelings of disconnection. While there have been many narrative,…

  12. Tunable magneto-optic modulation based on magnetically responsive nanostructured magnetic fluid

    Institute of Scientific and Technical Information of China (English)

    Bai Xue-Kun; Pu Sheng-Li; Wang Lun-Wei; Wang Xiang; Yu Guo-Jun; Ji Hong-Zhu

    2011-01-01

    Magnetic fluid is a kind of functional composite material with nanosized structure and unique optical properties.The tunable magneto-optic modulation of magnetic fluid under external magnetic field,achieved by adjusting the polarization direction of incident light,is investigated theoretically and experimentally in this work.The corresponding modulation depth and response time are obtained.The accompanying mechanisms are clarified by using the theory of dichroism of magnetic fluid and the aggregation/disintegration processes of magnetic particles within magnetic fluid when the external magnetic field turns on/off.

  13. Turbo-alternator-compressor design for supercritical high density working fluids

    Science.gov (United States)

    Wright, Steven A.; Fuller, Robert L.

    2013-03-19

    Techniques for generating power are provided. Such techniques involve a thermodynamic system including a housing, a turbine positioned in a turbine cavity of the housing, a compressor positioned in a compressor cavity of the housing, and an alternator positioned in a rotor cavity between the turbine and compressor cavities. The compressor has a high-pressure face facing an inlet of the compressor cavity and a low-pressure face on an opposite side thereof. The alternator has a rotor shaft operatively connected to the turbine and compressor, and is supported in the housing by bearings. Ridges extending from the low-pressure face of the compressor may be provided for balancing thrust across the compressor. Seals may be positioned about the alternator for selectively leaking fluid into the rotor cavity to reduce the temperature therein.

  14. Computational Fluid Dynamics at work - Design and Optimization of Microfluidic Applications

    DEFF Research Database (Denmark)

    Krühne, Ulrich; Bodla, Vijaya Krishna; Møllenbach, Jacob

    2012-01-01

    Computational Fluid Dynamics (CFD) is presented as a powerful tool to support design and optimization of microfluidic reactors. This is demonstrated by means of three case studies. First a three-dimensional scaffold for tissue engineering purposes is investigated using a combination of CFD...... and a simple biological model. The result is a suggestion of an improved geometry design. In the second case study a microfluidic cartridge of a novel automated in vitro fertilization device is presented, where the CFD model has supported the fluidic design of the microfluidic network in which the stem cells...... are grown. In the last case study a biocatalytic microfluidic reactor design is presented in which the material characteristics of substrates and products of the catalytic reaction can be investigated. As model system the transaminase catalyzed formation of methylbenzylamine (MBA) from acetophenone...

  15. Practice-Based Evidence: Delivering What Works

    Science.gov (United States)

    Brendtro, Larry K.; Mitchell, Martin L.

    2012-01-01

    Many methods claim to be Evidence-Based Practices. Yet success comes not from a particular practice, but principles that underlie all effective helping. This article uses the principle of consilience to tap knowledge from science, values, and practical experience.

  16. Why activity-based costing works.

    Science.gov (United States)

    Gabram, S G; Mendola, R A; Rozenfeld, J; Gamelli, R L

    1997-01-01

    With advancing technology and the quest for delineating the true cost of a procedure or diagnostic test, cost accounting techniques are being re-explored in the health care setting. Activity-based costing (ABC), adopted from other businesses, is one such example that has applications in the health industry. The purpose of this paper is to enhance the understanding of health care costs among physician providers, emphasizing a new approach--activity-based costing.

  17. Evaluation of Propylene Glycol-Based Fluids for Constellation Habitats and Vehicles

    Science.gov (United States)

    Lee, Steve

    2009-01-01

    Two fluid life tests have been conducted to evaluate propylene glycol-based fluids for use in Constellation habitats and vehicles. The first test was conducted from November 2008 to January 2009 to help determine the compatibility of the propylene glycol-based fluid selected for Orion at the time. When the first test uncovered problems with the fluid selection, an investigation and selection of a new fluid were conducted. A second test was started in March 2010 to evaluate the new selection. For the first test, the fluid was subjected to a thermal fluid loop that had flight-like properties, as compared to Orion. The fluid loop had similar wetted materials, temperatures, flow rates, and aluminum wetted surface area to fluid volume ratio. The test was designed to last for 10 years, the life expectancy of the lunar habitat. However, the test lasted less than two months. System filters became clogged with precipitate, rendering the fluid system inoperable. Upon examination of the precipitate, it was determined that the precipitate composition contained aluminum, which could have only come from materials in the test stand, as aluminum is not part of the original fluid composition. Also, the fluid pH was determined to have increased from 10.1, at the first test sample, to 12.2, at the completion of the test. This high of a pH is corrosive to aluminum and was certainly a contributing factor to the development of precipitate. Due to the problems encountered during this test, the fluid was rejected as a coolant candidate for Orion. A new propylene glycol-based fluid was selected by the Orion project for use in the Orion vehicle. The Orion project has conducted a series of screening tests to help verify that there will be no problems with the new fluid selection. To compliment testing performed by the Orion project team, a new life test was developed to test the new fluid. The new test bed was similar to the original test bed, but with some improvements based on experience

  18. Synthesis and Characterisation of Nano Silver Particle-based Magnetorheological Fluids for Brakes

    Directory of Open Access Journals (Sweden)

    Chiranjit Sarkar

    2015-05-01

    Full Text Available Magnetorheological (MR fluids can be used as brake friction materials subject to heat transfer properties of the fluids to dissipate the heat generated during braking action. The aim of this manuscript is to synthesise MR fluids having higher heat transfer properties than that of the conventional MR fluid. The coating of nano-silver-particles, having thermal conductivity more than five-times than that of iron particles used in the MR fluids, has been tried to enhance the heat dissipation rate of MR fluids. To perform feasibility study on usage of silver particles, three composition of MR fluids (without any silver particles, with 0.25 per cent weight and 0.50 per cent weight silver particles were synthesised. The scanning electron microscopic photographs and EDX analysis of the iron particles have been presented. Shear strengths of all three different compositions of MR fluids were measured using magnetorheometer and the results have been plotted. The effect of silver particles on shear stress of MR fluids has been described. A flywheel-based MR brake experimental setup was developed to analyse the performance of synthesised MR fluids. ‘T’ type thermocouples were used to avail the temperature distribution of the fabricated MR brake. The results of temperature distribution of brakes containing three different compositions of MR fluids have been presented and compared.Defence Science Journal, Vol. 65, No. 3, May 2015, pp.252-258, DOI: http://dx.doi.org/10.14429/dsj.65.7879

  19. 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…

  20. Work-Based Learning and Work-Integrated Learning: Fostering Engagement with Employers

    Science.gov (United States)

    Atkinson, Georgina

    2016-01-01

    Work-based learning and the inclusion of the world of work into tertiary students' learning lie at the heart of the Australian vocational education and training (VET) system. Traditionally this has been through apprenticeships and traineeships, which have a strong focus on "on-the-job" training, but also through "work-oriented"…

  1. Three Nodes Acoustic Element for Fluid-Structure Interaction Based on a Parameterized Variational Principle

    Directory of Open Access Journals (Sweden)

    Correa S.

    2011-10-01

    Full Text Available This article presents a finite element formulation based on a parameterized variational principle for solving plane problems of fluid-structure interaction using the displacements as state variable for both solid and fluid media. The circular spurious modes, typical of displacement formulations are avoided. The penalty parameter is not random because it is selected according to energy criterion. Finally the formulation is not sensible to the definition of the normal direction in the fluid-structure interface.

  2. Electrical breakdown strength characteristics of palm kernel oil ester-based dielectric fluids

    OpenAIRE

    Abdelmalik, A. A.; Fothergill, J; Dodd, S.J.

    2011-01-01

    Natural ester fluids have been synthesized from crude palm kernel oil for consideration as an alternative to mineral oil based insulating fluid. Chemical modification of the oil enhanced the physico-chemical properties of the fluid. This paper presents the statistical analysis of the AC electrical breakdown strength of the synthesized esters in comparison with the crude palm kernel oil sample. The breakdown test was carried out in accordance with ASTM 1816 test method using a bespoke test cel...

  3. Development of ER fluid-based actuators for rotorcraft flexbeam applications

    Science.gov (United States)

    Kamath, Gopalakrishna M.; Wereley, Norman M.

    1995-05-01

    A numerical study of electrorheological (ER) dampers is presented. Two models, the Newtonian and the Bingham plastic models are used to characterize the ER fluid behavior. Damping performance of two damper configurations, the Moving Electrode and the Fixed Electrode configurations, is studied. The effects of electrode gap sizes, the field strength and the ER fluid model used are quantified. The study provides a basis for design of ER-fluid based dampers.

  4. 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…

  5. Effects of working memory and attentional control training and their transfer onto fluid intelligence in early and late adulthood

    Directory of Open Access Journals (Sweden)

    Ludmiła Zając-Lamparska

    2016-01-01

    Full Text Available Background The interest in the possibility of improving cognitive functioning through training of basic cognitive processes is growing. This possibility is of particular importance for older adults, whose cognitive functions are weakened, and who may need cognitive rehabilitation. However, improvement of the performance in the tasks being trained is not the only goal of basic cognitive processes training. Far transfer, onto tasks different to the ones trained, and engaging other (usually complex processes, including fluid intelligence, is an important goal of such training. Yet, meta-analyses suggest that results of studies on the far transfer phenomenon vary, and are not conclusive. Participants and procedure One hundred and eighty healthy volunteers took part in this study. They were divided into groups: Experimental 1 (working memory training, Experimental 2 (attentional control training and Control (non-contact. Each of these groups included participants from the two age subgroups: early and late adulthood. Training involved 7 appointments and lasted for about 4 weeks. Additional measurements, including an assessment of fluid intelligence, were performed on each group at baseline, and at the end of training. Results Our results suggest that (a the training of basic cognitive processes in adults leads to an improvement in the correctness, but not the speed, at which tasks are performed, (b there is a transfer effect onto fluid intelligence, but this effect is weak, and (c the effects of basic cognitive process training depend on the kind of trained tasks, age of participants and the interactions between these two factors: working memory training is equally as effective in both age groups, whereas training of attentional control is particularly effective among older individuals, and has limited efficacy for young adults. Conclusions Finally, one can conclude that the effectiveness of basic cognitive function training is limited. However, it

  6. Tunable left-handed metamaterial based on electrorheological fluids

    Institute of Scientific and Technical Information of China (English)

    Yong Huang; Xiaopeng Zhao; Liansheng Wang; Chunrong Luo

    2008-01-01

    A tunable left-handed metamaterial consisting of a periodic array of the left-handed dendritic structure units infiltrated with electro-rheological fluids is demonstrated. Experimental results show that the passband can move from the original 8.50-10.60 GHz to 7.16-8.39 GHz after electrorheological fluids are infused. When adc (direct current) electric field of 666 V/mm is applied, the passband moves toward lower frequency of within 7.08-8.30 GHz. This method provides one convenient way to design adaptive metamaterials.

  7. 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

    The present report constitutes deliverable D 19 and D 23 of the OMNIITOX project and is the life cycle assessment part of the ECB case study (work package 5). The objectives of the case study have been to deliver empirical knowledge for the feasibility study carried out as part of WP5 and to deli......The present report constitutes deliverable D 19 and D 23 of the OMNIITOX project and is the life cycle assessment part of the ECB case study (work package 5). The objectives of the case study have been to deliver empirical knowledge for the feasibility study carried out as part of WP5...... and to deliver data and inspiration to other work packages (WP 7, 8 and 9). Specifically for this part of the case study (life cycle assessment part), the aims have been to apply LCA for comparing the use of different alternative substances in a specific application and to make a basis for comparison with the EU...... risk assessment approach for assessing the same substances. In the other part of the case study (Deliverable 9; Christensen & Olsen, 2002), the results of the Risk Assessments are summarised. In the original problem definition focus were on the use of SCCP and as an alternative MCCP in metal working...

  8. Investigation on phase shifting for a 4 K Stirling pulse tube cryocooler with He-3 as working fluid

    Science.gov (United States)

    Qiu, L. M.; Han, L.; Zhi, X. Q.; Dietrich, M.; Gan, Z. H.; Thummes, G.

    2015-07-01

    He-3 is generally recognized for its ability to provide more excellent thermophysical performance than He-4, especially in the 4 K temperature range. However, this was not always the case in our preliminary experiments on a three-stage Stirling-type pulse tube cryocooler (SPTC). Our ongoing studies, as reported in this paper, demonstrate that the different working fluids also affect the performance through their phase shifting capability. This feature has been passed over in large part by researchers considering refrigerant substitution. Unlike previous theoretical analyses that focus primarily on regenerator losses, this report investigates the effects of the working fluid on the phase angle at the cold end in order to quantitatively reveal the relationship between the lowest attainable temperature and the cooling capacity. The analysis agrees well with our experimental results on a three-stage SPTC. While running with the operating parameters optimized for He-3, the lowest temperature of the SPTC decreased from 5.4 K down to 4.03 K. This is the lowest refrigeration temperature ever achieved with a three-stage SPTC.

  9. 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.

  10. 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.

  11. 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...

  12. 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

  13. 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.

  14. Molecular group dynamics study on slip flow of thin fluid film based on the Hamaker hypotheses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The thin fluid film was assumed to consist of a number of spherical fluid molecular groups and the attractive forces of molecular group pairs were calculated by the derived equation according to the three Hamaker homogeneous material hypotheses. Regarding each molecular group as a dynamics individual, the simulation method for the shearing motion of multilayer fluid molecular groups, which was initiated by two moving walls, was proposed based on the Verlet velocity iterative algorithm. The simulations reveal that the velocities of fluid molecular groups change about their respective mean velocities within a narrow range in steady state. It is also found that the velocity slips occur at the wall boundary and in a certain number of fluid film layers close to the wall. Because the dimension of molecular group and the number of group layers are not restricted, the hypothetical thickness of fluid film model can be enlarged from nanometer to micron by using the proposed simulation method.

  15. [A comparative analysis of occupational risk in industry employees based on concentrations of some elements in teeth and body fluids].

    Science.gov (United States)

    Poczatek, Michał; Machoy, Zygmunt; Gutowska, Izabela; Chlubek, Dariusz

    2004-01-01

    Work safety and hygiene is a set of basic measures to protect workers from the negative effects of manufacturing processes. So far, numerous procedures for assessment of occupational health risk have been described. We measured the concentrations of some elements in teeth and body fluids of employees working in three different industries with an established production profile: Zakłady Naprawcze Taboru Kolejowego (repairs of rail vehicles), Philips Lighting Poland (production of lighting systems) and Metalplast (build ing furbishing factory). Different technologies were in place at each of these plants. Basing on laboratory analyses, the risk of exposure to chemical substances was evaluated. The study material included 100 extracted teeth, as well as body fluid samples (saliva, urine and blood) collected during routine health checks. Whenever possible, concentrations of the following elements were measured: calcium, magnesium, fluorine, phosphorus in the form of phosphates, potassium, sodium, iron, zinc, copper, cadmium, and lead. Metal elements were measured spectrophotometrically (ASA), fluorine with an ion-selective electrode, and phosphates with a colorimetric method. We found that concentrations of the elements in teeth and body fluids differed depending on the industry. For teeth, statistically significant differences applied to magnesium, phosphates, zinc, sodium, and potassium. In body fluids, statistically significant differences were found for calcium (blood and urine), magnesium (blood, urine and saliva), zinc (blood, urine and saliva), iron, lead and copper (urine). In conclusion, our findings may be helpful for monitoring safety at work in industrial plants.

  16. 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.

  17. Work-based learning in health and social care.

    Science.gov (United States)

    Phillips, Sue

    This article examines some of the issues encountered in helping to develop and facilitate work-based learning (WBL) in clinical areas from the author's perspective of APEL/WBL co-ordinator. The advantages of work-based learning to both organisations and practitioners are discussed, together with possible drawbacks. The article concludes by identifying the positive aspects, including that of practice development, but suggests caution in attempting to use work-based learning in all circumstances.

  18. 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

  19. Evaluation of regional work from ECG-gated SPECT images through solution of equations of continuity for fluids-mechanical cardiac work calculated using thin wall model.

    Science.gov (United States)

    Maeda, Hisatoshi

    2012-03-01

    Regional contraction work (RCW) of left ventricle (LV) was evaluated from cardiac perfusion images of ECG-gated single photon emission computed tomography (ECG-SPECT). The mechanical work was computed as a product of force and displaced distance. Force was determined from Laplace's law under a rectangle pressure. Deformation of wireframe representing LV was calculated from equations of continuity for two-dimensional fluids. Experiments were performed with homemade life-sized cardiac models. Total contraction work (TCW) and stroke work (SW) were 524.0 ± 166.1 mJ/beat and 709.8 ± 169.5 mJ/beat, respectively, in normal subjects (n = 23). Moderate correlation was seen between TCW and SW (y = -43.4 + 0.779 x, r = 0.815). The regional contraction amplitude (RCA), synchronous contraction index and RCW were 35.4 ± 3.5%, 95.4 ± 3.1% and 5.58 ± 0.97 mJ cm(-2)/beat in normal subjects, whereas those in patients with decreased ejection raction (EF) ≤ 30% (n = 6) were 19.6 ± 7.7%, 64.4 ± 32.2% and 2.58 ± 0.82 mJ cm(-2)/beat (p < 0.0001, Student's t-test). There was a poor correlation between RCW and RCA (y = 1.648 ± 0.116 x, r = 0.501) in normal subjects, suggesting that it might not be suitable to use RCA as an alternative to evaluate RCW.

  20. Study on a pulse tube cryocooler using gas mixture as its working fluid

    Science.gov (United States)

    Gao, C. M.; He, Y. L.; Chen, Z. Q.

    2000-01-01

    In order to improve the performance of a one-stage pulse tube cryocooler, gas mixtures are used for comparison, which have been used in other cryocoolers. A mixture of hydrogen and helium was investigated in this study. When the structure of the pulse tube is the same as mentioned in [C. Wang, P.Y. Wu, Zh.Q. Chen, Numerical modeling of an orifice pulse tube cryocooler, Cryogenics 32 (1992) 785] and the working conditions are: frequency 15 Hz, average pressure 1.1 MPa, hot end temperature 300 K and cold end temperature 80 K, it has been found that there are optimal molar percentage for the maximal cooling power and the maximal-coefficient of performance (COP) of this cryocooler.

  1. AN EXPERIMENTAL STUDY ON HEAT TRANSPORT CAPABILITY OF A TWO PHASE THERMOSYPHON CHARGED WITH DIFFERENT WORKING FLUIDS

    Directory of Open Access Journals (Sweden)

    M. Kannan

    2014-01-01

    Full Text Available In the present investigation a two phase thermosyphon has been fabricated to investigate the effect of operating parameters on the heat transport capability. The system consists of evaporator section, adiabatic section and condenser section with thermocouples located on the wall of thermosyphon. Electric heater was fixed on the bottom of the evaporator section and water jacket for cooling the condenser was placed on the top of the condenser section of the thermosyphon. The experiments were conducted with three different thermosyphons with inner diameters of 6.7, 9.5 and 12 mm. The variation of heat transport capability of the thermosyphon was studied for the input heat transfer rate ranging from 0 to 1200 W for various filling ratios and with operating temperature from 30 to 70°C. Water, methanol, ethanol and acetone were used as working fluids. The maximum heat transport capability was found to be high for water compared to other fluids such as ethanol, methanol and acetone at the operating temperatures higher than 40°C.

  2. Long Duration Life Test of Propylene Glycol Water Based Thermal Fluid Within Thermal Control Loop

    Science.gov (United States)

    Le, Hung; Hill, Charles; Stephan, Ryan A.

    2010-01-01

    Evaluations of thermal properties and resistance to microbial growth concluded that 50% Propylene Glycol (PG)-based fluid and 50% de-ionized water mixture was desirable for use as a fluid within a vehicle s thermal control loop. However, previous testing with a commercial mixture of PG and water containing phosphate corrosion inhibitors resulted in corrosion of aluminum within the test system and instability of the test fluid. This paper describes a follow-on long duration testing and analysis of 50% Propylene Glycol (PG)-based fluid and 50% de-ionized water mixture with inorganic corrosion inhibitors used in place of phosphates. The test evaluates the long-term fluid stability and resistance to microbial and chemical changes

  3. Structural vibration control via electrorheological-fluid-based actuators with adaptive viscous and frictional damping

    Science.gov (United States)

    Wang, K. W.; Kim, Y. S.; Shea, D. B.

    1994-10-01

    It has been recognized that the semi-active control concept is promising for vibration suppression of flexible structures and that the electrorheological (ER) fluid-based device is a good candidate for such applications. In this research, a new control law is developed to maximize the damping effect of ER dampers for structural vibration suppression under actuator constraints and viscous-frictional-combined damping. Numerical simulations and experimental work are carried out to evaluate the semi-active concept. It is illustrated that the performance of the semi-active system is superior to those of the critical damping and maximum damping variety. It is also concluded that the actuator frictional effect is significant, and should be considered in the controller design process.

  4. Fluid Interfaces

    DEFF Research Database (Denmark)

    Hansen, Klaus Marius

    2001-01-01

    Fluid interaction, interaction by the user with the system that causes few breakdowns, is essential to many user interfaces. We present two concrete software systems that try to support fluid interaction for different work practices. Furthermore, we present specificity, generality, and minimality...... as design goals for fluid interfaces....

  5. Problem-Based Learning in Social Work Education: Students’ experiences

    DEFF Research Database (Denmark)

    Monrad, Merete; Mølholt, Anne-Kirstine

    2017-01-01

    Problem-based learning (PBL) constitutes a promising way of integrating academia and social work practice because PBL fosters engagement with real-life problems and enhances important skills needed in social work practice. However, little attention has been given to social work students......’ 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...... they experience learning the most. Possible reasons for this discrepancy, and implications for teaching, are discussed....

  6. 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.

  7. Expansion of organic Rankine cycle working fluid in a cylinder of a low-speed two-stroke ship engine

    DEFF Research Database (Denmark)

    Larsen, Ulrik; Wronski, Jorrit; Andreasen, Jesper Graa

    2017-01-01

    Electricity and power produced from waste heat is particularly relevant in shipping because fuel expenses constitute the majority of the cost of operating the ships; however, the cost-benefit aspect limits the widespread implementation of waste heat recovery power units on ships. This paper...... for this concept. The evaluation of 104 working fluids points to cyclopropane, R245fa and R1234ze(z) as the most promising. The results suggest that the power produced by the organic Rankine cycle cylinder is at least equivalent to that of the cylinders operating with the diesel process. This enables potential...... fuel savings and emissions reductions of about 8.3% in the studied scenario....

  8. Work-Based Courses: Bringing College to the Production Line

    Science.gov (United States)

    Kobes, Deborah; Girardi, Amy

    2016-01-01

    Work-based courses are an innovative way to bring college to the production line by using the job as a learning lab. This toolkit provides guidance to community college administrators and faculty who are interested in bringing a work-based course model to their college. It contains video content and teaching tips that introduce the six steps of…

  9. Thermally stable drilling fluid additive comprised of a copolymer of catechol-based monomer

    Energy Technology Data Exchange (ETDEWEB)

    Patel, A.D.

    1986-06-17

    A water soluble polymer is described having thermal stability and exhibiting utility as an aqueous drilling fluid additive comprising: (a) a major portion of a catechol based monomer; (b) a minor portion of a dicarboxylic acid monomer.

  10. The fluid dynamics of a downer fluidised bed using a cluster-based approach (CBA

    Directory of Open Access Journals (Sweden)

    Germán González Silva

    2010-05-01

    Full Text Available The fluid dynamics of a downer reactor were numerically resolved by adapting a mathematical conservation model. The mathematical model was based on the solid and fluid properties and physical characteristics using a cluster-based approach (CBA. Comparing the numerical results to the experimental data found in the literature indicated that the mathematical model could satisfactorily predict the experimental data. The mathematical simulation determined that there were three fluid dynamic areas in the downer reactor which were characterized by accelerated, slowed-down and fully-developed flow. The fully developed flow area in the downer decreased with increased gas surface speed keeping solid flux constant.

  11. 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.

  12. 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].

  13. Reducing formation damage with microbubble based drilling fluid : understanding the blocking ability

    Energy Technology Data Exchange (ETDEWEB)

    Bjorndalen, N.; Kuru, E. [Alberta Univ., Edmonton, AB (Canada). School of Mining and Petroleum Engineering; Jossy, E.; Alvarez, J.M. [Alberta Research Council, Devon, AB (Canada)

    2007-07-01

    Micro-bubble based drilling fluids use gas bubbles to bridge pores in porous media. The microbubbles can be removed during the initial stages of production to reduce costs associated with stimulation processes. This paper provided details of experiments conducted to investigate pore blocking mechanisms. Micromodel cells were used with different pressure rates and fluid compositions. A xanthan gum-water mixture was used as a base drilling fluid. An anionic surfactant was added to the base fluid for aphronization. The resulting stable foam was injected into the micromodel, where it blocked porous media. The analysis demonstrated that an aphron of 60 {mu}m bubble will invade porous media with a pore diameter of 50 {mu} at approximately 10 kPa. The foam was effectively removed by water injection, which indicated that the effects of the foam were irreversible. Less fluid and surfactant was needed to achieve desired flow rates when the foam was used. It was concluded that drilling with aphronized fluid will reduce formation damage. Further research is required to determine maximum flow pressure of the aphronized fluid in porous media. 24 refs., 1 tab., 17 figs.

  14. Numerical simulation on fault water-inrush based on fluid-solid coupling theory

    Institute of Scientific and Technical Information of China (English)

    HUANG Han-fu; MAO Xian-biao; YAO Bang-hua; PU Hai

    2012-01-01

    About 75% water-inrush accidents in China are caused by geological structure such as faults,therefore,it is necessary to investigate the water-inrush mechanism of faults to provide references for the mining activity above confined water.In this paper,based on the fluid-solid coupling theory,we built the stress-seepage coupling model for rock,then we combined with an example of water-inrush caused by fault,studied the water-inrush mechanism by using the numerical software COMSOL Mutiphysics,analyzed the change rule of shear stress,vertical stress,plastic area and water pressure for stope with a fault,and estimated the water-inrush risk at the different distances between working faces and the fault.The numerical simulation results indicate that:(1) the water-inrush risk will grow as the decrease of the distance between working face and the fault;(2) the failure mode of the rock in floor with fault is shear failure; (3) the rock between water-containing fault and working face failure is the reason for water-inrush.

  15. From a quasi-static fluid-based evolutionary topology optimization to a generalization of BESO

    Science.gov (United States)

    Daróczy, László; Jármai, Károly

    2015-05-01

    A new algorithm is proposed for topology optimization based on a fluid dynamics analogy. It possesses characteristics similar to most well-known methods, such as the Evolutionary Structural Optimization (ESO)/Bidirectional Evolutionary Structural Optimization (BESO) method due to Xie and Steven (1993, "A Simple Evolutionary Procedure for Structural Optimisation." Computers and Structures 49 (5): 885-896.), which works with discrete values, and the Solid Isotropic Material with Penalization (SIMP) method due to Bendsøe (1989, "Optimal Shape Design as aMaterial Distribution Problem." Structural Optimization 1 (4): 193-202.) and Zhou and Rozvany (1991, "The COCAlgorithm-Part II: Topological, Geometry and Generalized Shape Optimization." Computer Methods in Applied Mechanics and Engineering 89 (1-3): 309-336.) (using Optimality Criterion (OC) or Method of Moving Asymptotes (MMA)), which works with intermediate values, as it is able to work both with discrete and intermediate densities, but always yields a solution with discrete densities. It can be proven mathematically that the new method is a generalization of the BESO method and using appropriate parameters it will operate exactly as the BESO method. The new method is less sensitive to rounding errors of the matrix solver as compared to the BESO method and is able to give alternative topologies to well-known problems. The article presents the basic idea and the optimization algorithm, and compares the results of three cantilever optimizations to the results of the SIMP and BESO methods.

  16. A Framework for Interactive Work Design based on Digital Work Analysis and Simulation

    CERN Document Server

    Ma, Liang; Fu, Huanzhang; Guo, Yang; Chablat, Damien; Bennis, Fouad; 10.1002/hfm.20178

    2010-01-01

    Due to the flexibility and adaptability of human, manual handling work is still very important in industry, especially for assembly and maintenance work. Well-designed work operation can improve work efficiency and quality; enhance safety, and lower cost. Most traditional methods for work system analysis need physical mock-up and are time consuming. Digital mockup (DMU) and digital human modeling (DHM) techniques have been developed to assist ergonomic design and evaluation for a specific worker population (e.g. 95 percentile); however, the operation adaptability and adjustability for a specific individual are not considered enough. In this study, a new framework based on motion tracking technique and digital human simulation technique is proposed for motion-time analysis of manual operations. A motion tracking system is used to track a worker's operation while he/she is conducting a manual handling work. The motion data is transferred to a simulation computer for real time digital human simulation. The data ...

  17. 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.

  18. An Eulerian-based Bubble Dynamics Model for Computational Fluid Dynamics

    Science.gov (United States)

    Balu, Asish; Kinzel, Michael

    2015-11-01

    Cavitation dynamics of nuclei are largely governed by the Rayleigh-Plesset Equation (RPE). This research explores the implementation of a one-way coupling to the solution of the RPE to a computational fluid dynamics (CFD) simulation in an Eulerian-framework. In this work, we used transport equations (i.e., advection) of the bubble radius and bubble growth rate, both of which are governed by advection mechanisms and coupling to the RPE through the CFD pressure field. The method is validated in the context of hypothetical pressure fields by prescribing a temporally varying pressure. Then, it is extended to one-way coupling with cavitation development in three different flow situations: (1) flow over a cylinder, (2) bubble formation during a bottle collapse event, and (3) cavitation in a tip vortex. In the context of these flows, the CFD simulations replicate an equivalent MATLAB-based solution to the RPE, thus validating the model. Additionally, an analytical formulation for appropriate upper and lower bounds for the bubble's physical properties is presented. These boundary values allow the CFD solver to run at larger time steps, therefore increasing the rate of convergence as well as maintaining solution accuracy. The results from this work suggest that Eulerian-based RPE cavitation models are practical and have the potential to simulate large numbers of bubbles that challenge Lagrangian methods.

  19. Work.

    Science.gov (United States)

    Haines, Annette M.

    2003-01-01

    Draws upon Maria Montessori's writings to examine work as a universal human tendency throughout life. Discusses the work of adaptation of the infant, work of "psycho-muscular organism" for the preschooler, work of the imagination for the elementary child, community work of the adolescent, and work of the adult. Asserts that…

  20. 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)

  1. Analysis of a Vertical Flat Heat Pipe Using Potassium Working Fluid and a Wick of Compressed Nickel Foam

    Directory of Open Access Journals (Sweden)

    Geir Hansen

    2016-03-01

    Full Text Available Heat at high temperatures, in this work 400–650 °C, can be recovered by use of cooling panels/heat pipes in the walls of aluminum electrolysis cells. For this application a flat vertical heat pipe for heat transfer from a unilateral heat source was analyzed theoretically and in the laboratory, with special emphasis on the performance of the wick. In this heat pipe a wick of compressed nickel foam covered only the evaporator surface, and potassium was used as the working fluid. The magnitudes of key thermal resistances were estimated analytically and compared. Operating temperatures and wick performance limits obtained experimentally were compared to predictions. Thermal deformation due to unilateral heat flux was analyzed by the use of COMSOL Multiphysics®. The consequences of hot spots at different locations on the wick were analyzed by use of a numerical 2D model. A vertical rectangular wick was shown to be most vulnerable to hot spots at the upper corners.

  2. 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.

  3. Sterically stabilized water based magnetic fluids: Synthesis, structure and properties

    Science.gov (United States)

    Bica, Doina; Vékás, Ladislau; Avdeev, Mikhail V.; Marinică, Oana; Socoliuc, Vlad; Bălăsoiu, Maria; Garamus, Vasil M.

    2007-04-01

    Magnetic fluids (MFs), prepared by chemical co-precipitation followed by double layer steric and electrostatic (combined) stabilization of magnetite nanoparticles dispersed in water, are presented. Several combinations of surfactants with different chain lengths (lauric acid (LA), myristic acid (MA), oleic acid (OA) and dodecyl-benzene-sulphonic acid (DBS)) were used, such as LA+LA, MA+MA, LA+DBS, MA+DBS, OA+DBS, OA+OA and DBS+DBS. Static light scattering, transmission electron microscopy, small angle neutron scattering, magnetic and magneto-rheological measurements revealed that MFs with MA+MA or LA+LA biocompatible double layer covered magnetite nanoparticles are the most stable colloidal systems among the investigated samples, and thus suitable for biomedical applications.

  4. Sterically stabilized water based magnetic fluids: Synthesis, structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Bica, Doina [Laboratory of Magnetic Fluids, Center for Fundamental and Advanced Technical Research, Romanian Academy, Timisoara Division, Bd. Mihai Viteazul 24, 300223 Timisoara (Romania); Vekas, Ladislau [Laboratory of Magnetic Fluids, Center for Fundamental and Advanced Technical Research, Romanian Academy, Timisoara Division, Bd. Mihai Viteazul 24, 300223 Timisoara (Romania) and National Centre for Engineering of Systems with Complex Fluids, University Politehnica Timisoara, Bd. Mihai Viteazul 1, 300222 Timisoara (Romania)]. E-mail: vekas@acad-tim.tm.edu.ro; Avdeev, Mikhail V. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Marinica, Oana [National Centre for Engineering of Systems with Complex Fluids, University Politehnica Timisoara, Bd. Mihai Viteazul 1, 300222 Timisoara (Romania); Socoliuc, Vlad [National Institute R and D for Electrochemistry and Condensed Matter, Str. Diaconu Coressi 144, 300588 Timisoara (Romania); Balasoiu, Maria [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Garamus, Vasil M. [GKSS Research Centre, Geesthacht (Germany)

    2007-04-15

    Magnetic fluids (MFs), prepared by chemical co-precipitation followed by double layer steric and electrostatic (combined) stabilization of magnetite nanoparticles dispersed in water, are presented. Several combinations of surfactants with different chain lengths (lauric acid (LA), myristic acid (MA), oleic acid (OA) and dodecyl-benzene-sulphonic acid (DBS)) were used, such as LA+LA, MA+MA, LA+DBS, MA+DBS, OA+DBS, OA+OA and DBS+DBS. Static light scattering, transmission electron microscopy, small angle neutron scattering, magnetic and magneto-rheological measurements revealed that MFs with MA+MA or LA+LA biocompatible double layer covered magnetite nanoparticles are the most stable colloidal systems among the investigated samples, and thus suitable for biomedical applications.

  5. Fluid transport due to nonlinear fluid-structure interaction

    Energy Technology Data Exchange (ETDEWEB)

    Soendergaard Jensen, J.

    1996-08-01

    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 uni-directional 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 analyzed numerically mode of vibration seems to be most effective for high mean fluid speed, whereas higher modes of vibration can be used to transport fluid with the same fluid speed but with smaller magnitude of pipe vibrations. The effect of the nonlinear geometrical terms is analyzed and these terms are shown to affect the response for higher modes of vibration. Experimental investigations show good agreement with theoretical predictions. (au) 16 refs.

  6. Simulation of Magnetorheological Fluids Based on Lattice Boltzmann Method with Double Meshes

    Directory of Open Access Journals (Sweden)

    Xinhua Liu

    2012-01-01

    Full Text Available In order to study the rheological characteristics of magnetorheological fluids, a novel approach based on the two-component Lattice Boltzmann method with double meshes was proposed, and the micro-scale structures of magnetorheological fluids in different strength magnetic fields were simulated. The framework composed of three steps for the simulation of magnetorheological fluids was addressed, and the double meshes method was elaborated. Moreover, the various internal and external forces acting on the magnetic particles were analyzed and calculated. The two-component Lattice Boltzmann model was set up, and the flowchart for the simulation of magnetorheological fluids based on the two-component Lattice Boltzmann method with double meshes was designed. Finally, a physics experiment was carried out, and the simulation examples were provided. The comparison results indicated that the proposed approach was feasible, efficient, and outperforming others.

  7. Grey Documentation as a Knowledge Base in Social Work.

    Science.gov (United States)

    Berman, Yitzhak

    1994-01-01

    Defines grey documentation as documents issued informally and not available through normal channels and discusses the role that grey documentation can play in the social work knowledge base. Topics addressed include grey documentation and science; social work and the empirical approach in knowledge development; and dissemination of grey…

  8. Design-based practice: a new perspective for social work.

    Science.gov (United States)

    Cohen, Burton J

    2011-10-01

    Evidence-based practice (EBP) has emerged as an alternative to traditional social work practice and has ignited a new round in the decades-old debate about the relationship between knowledge and practice in the field. This article identifies several limitations inherent in the EBP perspective and argues that it would be unfortunate if EBP were to become the new paradigm for social work practice and education. It also presents a new perspective for social work called design-based practice (DBP), which is based on the work of Herbert Simon and Mary Parker Follett, and compares this perspective with EBP and authority-based practice. DBP rests on the belief that knowledge is derived from experience and interactions between practitioners and clients and that professional practice should be primarily concerned with "how things ought to be."

  9. 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.

  10. 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.

  11. Flammability Testing of Fabrics Treated with Oil-Based Shear Thickening Fluids

    Science.gov (United States)

    2014-05-01

    thickening fluid (STF) are evaluated under flammability testing. The tested fabrics include a woven cotton-nylon blend, a woven Kevlar textile, and a...hybrid ultrahigh molecular weight polyethylene (UHMWPE) – Kevlar felt. The oil-based STF is a colloid of silica nanoparticles in a paraffin oil. Test...enhanced flammability resistance. 15. SUBJECT TERMS shear thickening fluid, Kevlar , flammability 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

  12. Waste Contaminants at Military Bases Working Group report

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-04

    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.

  13. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Alborch, A [School of Philosophy, Humanities and Arts. National University of San Juan. I de la Roza 230 (Oeste). CP 5400. San Juan (Argentina); Puzzella, A [School of Philosophy, Humanities and Arts. National University of San Juan. I de la Roza 230 (Oeste). CP 5400. San Juan (Argentina); Lopez, N [School of Engineering. National University of San Juan. Av. San MartIn 1109 (Oeste). CP 5400. San Juan (Argentina); Cabrera, L [' Col. Central Universitario Dr. M. Moreno' Secondary School. National University of San Juan. I de la Roza 230 (Oeste). CP 5400. San Juan (Argentina); Zabala, A [School of Engineering. National University of San Juan. Av. San MartIn 1109 (Oeste). CP 5400. San Juan (Argentina); Demartini, H [School of Engineering. National University of San Juan. Av. San MartIn 1109 (Oeste). CP 5400. San Juan (Argentina)

    2007-11-15

    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.

  15. 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.

  16. 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.

  17. 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.

  18. Functional diversity and dynamics of bacterial communities in a membrane bioreactor for the treatment of metal-working fluid wastewater.

    Science.gov (United States)

    Grijalbo, Lucía; Garbisu, Carlos; Martín, Iker; Etxebarria, Javier; Gutierrez-Mañero, F Javier; Lucas Garcia, Jose Antonio

    2015-12-01

    An extensive microbiological study has been carried out in a membrane bioreactor fed with activated sludge and metal-working fluids. Functional diversity and dynamics of bacterial communities were studied with different approaches. Functional diversity of culturable bacterial communities was studied with different Biolog™ plates. Structure and dynamics of bacterial communities were studied in culturable and in non-culturable fractions using a 16S rRNA analysis. Among the culturable bacteria, Alphaproteobacteria and Gammaproteobacteria were the predominant classes. However, changes in microbial community structure were detected over time. Culture-independent analysis showed that Betaproteobacteria was the most frequently detected class in the membrane bioreactor (MBR) community with Zoogloea and Acidovorax as dominant genera. Also, among non-culturable bacteria, a process of succession was observed. Longitudinal structural shifts observed were more marked for non-culturable than for culturable bacteria, pointing towards an important role in the MBR performance. Microbial community metabolic abilities assessed with Biolog™ Gram negative, Gram positive and anaerobic plates also showed differences over time for Shannon's diversity index, kinetics of average well colour development, and the intensely used substrates by bacterial community in each plate.

  19. 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

  20. A comparison of field-dependent rheological properties between spherical and plate-like carbonyl iron particles-based magneto-rheological fluids

    Science.gov (United States)

    Tan Shilan, Salihah; Amri Mazlan, Saiful; Ido, Yasushi; Hajalilou, Abdollah; Jeyadevan, Balachandran; Choi, Seung-Bok; Azhani Yunus, Nurul

    2016-09-01

    This work proposes different sizes of the plate-like particles from conventional spherical carbonyl iron (CI) particles by adjusting milling time in the ball mill process. The ball mill process to make the plate-like particles is called a solid-state powder processing technique which involves repeated welding, fracturing and re-welding of powder particles in a high-energy ball mill. The effect of ball milling process on the magnetic behavior of CI particles is firstly investigated by vibrating sample magnetometer. It is found form this investigation that the plate-like particles have higher saturation magnetization (about 8%) than that of the spherical particles. Subsequently, for the investigation on the sedimentation behavior the cylindrical measurement technique is used. It is observed from this measurement that the plate-like particles show slower sedimentation rate compared to the spherical particles indicating higher stability of the MR fluid. The field-dependent rheological properties of MR fluids based on the plate-like particles are then investigated with respect to the milling time which is directly connected to the size of the plate-like particles. In addition, the field-dependent rheological properties such as the yield stress are evaluated and compared between the plate-like particles based MR fluids and the spherical particles based MR fluid. It is found that the yield shear stress of the plate-like particles based MR fluid is increased up to 270% compared to the spherical particles based MR fluid.

  1. In vitro dermal penetration of 4-chloro-3-methylphenol from commercial metal working fluid and aqueous vehicles.

    Science.gov (United States)

    Frasch, H Frederick; Zang, Lun-Yi; Barbero, Ana M; Anderson, Stacey E

    2010-01-01

    The biocide 4-chloro-3-methylphenol (CMP, CAS number 59-50-7) is a common additive to metal-working fluids (MWF) and building materials. National Institute for Occupational Safety and Health (NIOSH) researchers previously identified and quantified CMP in a commercial water-soluble MWF, TRIM VX, and demonstrated irritancy and sensitization potential of both TRIM VX and CMP alone after dermal exposure in a murine model. In the current study, the in vitro human epidermal permeability of CMP contained in a working dilution of TRIM VX (20% in water) was evaluated and, for comparison, permeability from an aqueous buffer was also assessed. CMP penetration was also measured from transient exposures to 20% TRIM VX. To address differences in penetration rates from 20% TRIM VX and from buffer, the role of thermodynamic activity of CMP in the 2 vehicles on dermal penetration was investigated. Static headspace gas chromatography was used to measure vapor pressures and infer fractional thermodynamic activities of CMP in the mixtures. Permeability coefficient (k(p)) of CMP from 20% TRIM VX was (4.1 +/- 0.8) x 10(-3) cm/h (mean +/- SD, n = 5), and CMP was found at a concentration of 3555 +/- 191 microg/ml in this donor. In contrast, k(p) was 0.18 +/- 0.03 cm/h (n = 5) at a similar concentration (3919 +/- 240) from buffer donor. Steady-state fluxes from 20% TRIM VX and buffer were comparable when expressed as functions of thermodynamic activity of CMP in the donor, rather than as concentrations. Transient (20 or 40 min) exposures of epidermal membranes to 20% TRIM VX (n = 4) resulted in total penetration of 4.2 +/- 1.2 and 7.3 +/- 0.8 microg/cm(2), respectively; these amounts are comparable to amounts predicted using a simple algebraic equation.

  2. 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.

  3. 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…

  4. Intelligent predicting approach of peritoneal fluid absorption rate based-on neural network

    Institute of Scientific and Technical Information of China (English)

    Mei ZHANG; Yueming HU; Tao WANG

    2003-01-01

    This paper addresses the important intelligent predicting problem of peritoneal absorption rate in the peritoneal dialysis treament process of renal failure. As the index of dialysis adequacy, KT/V and Ccr are widely used and accepted. However,growing evidence suggests that the fluid balance may play a critical role in dialysis adequacy and patient outcome. Peritoneal fluid absorption decreases the peritoneal fluid removal. Understanding the peritoneal fluid absorption rate will help clinicians to opthnize the dialysis dwell time. The neural network approach is applied to the prediction of peritoneal absorption rate. Compared with multivariable regression method, the experimental results showed that neural network method has an advantage over multivariable regression. The application of this predicting method based-on neural network in clinic is instructive.

  5. 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.

  6. Particle-based simulation of hydraulic fracture and fluid/heat flow in geothermal reservoirs

    Science.gov (United States)

    Mora, Peter; Wang, Yucang; Alonso-Marroquin, Fernando

    2013-06-01

    Realizing the potential of geothermal energy as a cheap, green, sustainable resource to provide for the planet's future energy demands that a key geophysical problem be solved first: how to develop and maintain a network of multiple fluid flow pathways for the time required to deplete the heat within a given region. We present the key components for micro-scale particle-based numerical modeling of hydraulic fracture, and fluid and heat flow in geothermal reservoirs. They are based on the latest developments of ESyS-Particle - the coupling of the Lattice Solid Model (LSM) to simulate the nonlinear dynamics of complex solids with the Lattice Boltzmann Method (LBM) applied to the nonlinear dynamics of coupled fluid and heat flow in the complex solid-fluid system. The coupled LSM/LBM can be used to simulate development of fracture systems in discontinuous media, elastic stress release, fluid injection and the consequent slip at joint surfaces, and hydraulic fracturing; heat exchange between hot rocks and water within flow pathways created through hydraulic fracturing; and fluid flow through complex, narrow, compact and gouge-or powder-filled fracture and joint systems. We demonstrate the coupled LSM/LBM to simulate the fundamental processes listed above, which are all components for the generation and sustainability of the hot-fractured rock geothermal energy fracture systems required to exploit this new green-energy resource.

  7. Effect of working fluids and internal diameters on thermal performance of vertical and horizontal closed-loop pulsating heat pipes with multiple heat sources

    Directory of Open Access Journals (Sweden)

    Kammuang-Lue Niti

    2016-01-01

    Full Text Available Some electrical applications have a number of heat sources. The closed-loop pulsating heat pipe (CLPHP is applied to transfer heat from these devices. Since the CLPHP primarily transfers heat by means of the working fluid’s phase change in a capillary tube, the thermal performance of the CLPHP significantly depends on the working fluid type and the tube’s internal diameter. In order to provide the fundamental information for manufacturers of heat exchangers, this study on the effect of working fluids and internal diameters has been conducted. Three electrical plate heaters were installed on the CLPHP as the heat sources. The experiments were conducted by varying the working fluid to be R123, ethanol, and water, and the internal diameter to be 1.0 mm, 1.5 mm, and 2.0 mm. For each set of the same working fluid and internal diameter, the input heat fluxes of the heat sources were also made to vary within six different patterns. It can be concluded that when the latent heat of evaporation increases - in the case of vertical CLPHP - and when the dynamic viscosity of the liquid increases - in the case of horizontal CLPHP - the thermal performance decreases. Moreover, when the internal diameter increases, the thermal performance increases for both of vertical and horizontal CLPHPs.

  8. 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......Dual systems of vocational education and training that build on the tradition of apprenticeship have many attractive qualities, seen from a political perspective. VET systems that comprise a significant amount of work-based training, provide a valuable alternative for young people who chose...... with formal education in a dual system. But historically in many countries, apprenticeship has given way to school-based forms of VET and dual systems are only dominant in a limited number of countries. Furthermore, the integration of work-based training in an educational programme involves many challenges...

  9. Viscous fluid damping in a laterally oscillating finger of a comb-drive micro-resonator based on micro-polar fluid theory

    Science.gov (United States)

    Azma, Sahra; Rezazadeh, Ghader; Shabani, Rasoul; Alizadeh-Haghighi, Elnaz

    2016-06-01

    Viscous damping is a dominant source of energy dissipation in laterally oscillating micro-structures. In micro-resonators in which the characteristic dimensions are comparable to the dimensions of the fluid molecules, the assumption of the continuum fluid theory is no longer justified and the use of micro-polar fluid theory is indispensable. In this paper a mathematical model was presented in order to predict the viscous fluid damping in a laterally oscillating finger of a micro-resonator considering micro-polar fluid theory. The coupled governing partial differential equations of motion for the vibration of the finger and the micro-polar fluid field have been derived. Considering spin and no-spin boundary conditions, the related shape functions for the fluid field were presented. The obtained governing differential equations with time varying boundary conditions have been transformed to an enhanced form with homogenous boundary conditions and have been discretized using a Galerkin-based reduced order model. The effects of physical properties of the micro-polar fluid and geometrical parameters of the oscillating structure on the damping ratio of the system have been investigated.

  10. Viscous fluid damping in a laterally oscillating finger of a comb-drive micro-resonator based on micro-polar fluid theory

    Institute of Scientific and Technical Information of China (English)

    Sahra Azma; Ghader Rezazadeh; Rasoul Shabani; Elnaz Alizadeh-Haghighi

    2016-01-01

    Viscous damping is a dominant source of energy dissipation in laterally oscillating micro-structures. In micro-resonators in which the characteristic dimensions are compa-rable to the dimensions of the fluid molecules, the assumption of the continuum fluid theory is no longer justified and the use of micro-polar fluid theory is indispensable. In this paper a mathematical model was presented in order to predict the viscous fluid damping in a laterally oscillating finger of a micro-resonator considering micro-polar fluid theory. The coupled governing partial differential equations of motion for the vibration of the finger and the micro-polar fluid field have been derived. Considering spin and no-spin boundary conditions, the related shape functions for the fluid field were presented. The obtained governing differential equations with time varying boundary conditions have been trans-formed to an enhanced form with homogenous boundary conditions and have been discretized using a Galerkin-based reduced order model. The effects of physical properties of the micro-polar fluid and geometrical parameters of the oscillat-ing structure on the damping ratio of the system have been investigated.

  11. 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)

  12. Influence of size, shape, type of nanoparticles, type and temperature of the base fluid on natural convection MHD of na

    Directory of Open Access Journals (Sweden)

    P. Sudarsana Reddy

    2016-03-01

    Full Text Available In this paper, we have presented MHD natural convection boundary layer flow, heat and mass transfer characteristics of nanofluid through porous media over a vertical cone influenced by different aspects of nanoparticles such as size, shape, type of nanoparticles and type of the base fluid and working temperature of base fluid. To increase the physical significance of the problem, we have taken dynamic viscosity and thermal conductivity as the functions of local volume fraction of nanoparticles. The drift-flux model of nanofluids, Brownian motion, thermophoresis, and enhancement ratio parameters are also considered in the present analysis. The influence of non-dimensional parameters such as magnetic field (M, buoyancy ratio parameter (Nr, conductivity parameter (Nc, viscosity parameter (Nv, Brownian motion parameter (Nb, thermophoresis parameter (Nt, Lewis number (Le on velocity, temperature and volume fraction of nanoparticles in the boundary layer region is examined in detail. Furthermore the impact of these parameters on local Nusselt number (Nux and enhancement ratio hnfhbf is also investigated. The results of present study reveal that significant natural convection heat transfer enhancement is noticed as the size of nanoparticles decreases. Moreover, type of the nanoparticles and type of the base fluid also influenced the natural convection heat transfer.

  13. Dynamic characteristics of Semi-active Hydraulic Engine Mount Based on Fluid-Structure Interaction FEA

    OpenAIRE

    Tian Jiande; Jiang Xue; Liu Guozheng; Shi Wenku; Liu Baoquan; Ma Meiqin

    2015-01-01

    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 ou...

  14. 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.)

  15. Fluid identification in tight sandstone reservoirs based on a new rock physics model

    Science.gov (United States)

    Sun, Jianmeng; Wei, Xiaohan; Chen, Xuelian

    2016-08-01

    To identify pore fluids, we establish a new rock physics model named the tight sandstone dual-porosity model based on the Voigt-Reuss-Hill model, approximation for the Xu-White model and Gassmann’s equation to predict elastic wave velocities. The modeling test shows that predicted sonic velocities derived from this rock physics model match well with measured ones from logging data. In this context, elastic moduli can be derived from the model. By numerical study and characteristic analyzation of different elastic properties, a qualitative fluid identification method based on Poisson’s ratio and the S-L dual-factor method based on synthetic moduli is proposed. Case studies of these two new methods show the applicability in distinguishing among different fluids and different layers in tight sandstone reservoirs.

  16. 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.

  17. Effect of Evaporator Section Lengths and Working Fluids on Operational Limit of Closed Loop Oscillating Heat Pipes with Check Valves (CLOHP/CV

    Directory of Open Access Journals (Sweden)

    P. Meena

    2009-01-01

    Full Text Available This research aims to the effect of evaporator section lengths and working fluids on operational limit of closed loop oscillating heat pipes with check valves (CLOHP/CV with R123 Ethanol and Water were used as the working fluids. A set of CLOHP/CV was made of copper tubes in combination of following dimension: 1.77 mm inside diameter: 10 turns: 5, 10 and 15 cm equal lengths for evaporator, adiabatic and condenser sections. The working fluid was filled in the tube at the filling ratio of 50%. The evaporator section was given heat by heater while the condenser section was cooled by volume water in a cold bath. The adiabatic section was properly insulated. In the test operation. Which the temperature at the adiabatic section was controlled at 60°C in steady-state condition. From The obtained results obtained, it could be concluded as follows. When the evaporator lengths increased from 5 cm to 10 and 15 cm the critical heat transfer flux decreased. There was working fluids change from R123 to Ethanol and water the critical heat flux decreased.

  18. Fluid viscous damping as an alternative to base isolation

    Energy Technology Data Exchange (ETDEWEB)

    Haskell, G. [Hawn Engineering, Modesto, CA (United States); Lee, D. [Taylor Devices, Santa Monica, CA (United States). West Coast Div.

    1996-12-01

    Base isolation is an effective way to protect large structures from earthquake damage. It is a costly approach, as the entire structure must be supported on elastomeric or sliding bearings. Viscous dampers distributed throughout the otherwise conventional structure can achieve the same result at significantly lower cost. This paper describes how to install viscous dampers in a structure, and gives several examples.

  19. Queue-based random-access algorithms: Fluid limits and stability issues

    Directory of Open Access Journals (Sweden)

    Javad Ghaderi

    2014-09-01

    Full Text Available We use fluid limits to explore the (instability properties of wireless networks with queue-based random-access algorithms. Queue-based random-access schemes are simple and inherently distributed in nature, yet provide the capability to match the optimal throughput performance of centralized scheduling mechanisms in a wide range of scenarios. Unfortunately, the type of activation rules for which throughput optimality has been established, may result in excessive queue lengths and delays. The use of more aggressive/persistent access schemes can improve the delay performance, but does not offer any universal maximum-stability guarantees. In order to gain qualitative insight and investigate the (instability properties of more aggressive/persistent activation rules, we examine fluid limits where the dynamics are scaled in space and time. In some situations, the fluid limits have smooth deterministic features and maximum stability is maintained, while in other scenarios they exihibit random oscillatory characteristics, giving rise to major technical challenges. In the latter regime, more aggressive access schemes continue to provide maximum stability in some networks, but may cause instability in others. In order to prove that, we focus on a particular network example and conduct a detailed analysis of the fluid limit process for the associated Markov chain. Specifically, we develop a novel approach based on stopping time sequences to deal with the switching probabilities governing the sample paths of the fluid limit process. Simulation experiments are conducted to illustrate and validate the analytical results.

  20. 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.

  1. 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...

  2. Large capacity, multi-fuel, and high temperature working fluid heaters to optimize CSP plant cost, complexity and annual generation

    Science.gov (United States)

    Peterseim, J. H.; Viscuso, L.; Hellwig, U.; McIntyre, P.

    2016-05-01

    This paper analyses the potential to optimize high temperature fluid back-up systems for concentrating solar power (CSP) plants by investigating the cost impact of component capacity and the impact of using multiple fuels on annual generation. Until now back-up heaters have been limited to 20MWth capacity but larger units have been realised in other industries. Installing larger units yields economy-of-scale benefits through improved manufacturing, optimised transport, and minimized on-site installation work. Halving the number of back-up boilers can yield cost reduction of 23% while minimizing plant complexity and on-site construction risk. However, to achieve these benefits it is important to adapt the back-up heaters to the plant's requirements (load change, capacity, minimum load, etc.) and design for manufacture, transport and assembly. Despite the fact that biomass availability is decreasing with increasing direct normal irradiance (DNI), some biomass is available in areas suitable for CSP plants. The use of these biomass resources is beneficial to maximise annual renewable energy generation, substitute natural gas, and use locally/seasonally available biomass resources that may not be used otherwise. Even small biomass quantities of only 50,000 t/a can increase the capacity factor of a 50MWe parabolic trough plant with 7h thermal energy storage from 40 to 49%. This is a valuable increase and such a concept is suitable for new plants and retrofit applications. However, similar to the capacity optimisation of back-up heaters, various design criteria have to be considered to ensure a successful project.

  3. Effects of pH amendment on metal working fluid wastewater biological treatment using a defined bacterial consortium.

    Science.gov (United States)

    van der Gast, Christopher J; Thompson, Ian P

    2005-02-05

    The aim of this study was to determine whether pH amendment of a highly alkaline metal working fluid (MWF) wastewater would improve biological treatment in a bioreactor system following introduction of a bacterial inoculum (comprised of the following strains: Agrobacterium radiobacter, Comamonas testosteroni, Methylobacterium mesophilicum, Microbacterium esteraromaticum, and Microbacterium saperdae). The pH values tested were 6, 7, 8, and 9. Three replicate batch mode bioreactors inoculated with the bacterial inoculum (plus an abiotic control bioreactor) were operated for each of the four pH conditions. After 14 days, the final mean chemical oxygen demand (COD) reduction at pH 9 was 50 +/- 1.4%; at pH 8, 58 +/- 1.4%; pH 7, 65 +/- 1.0%; and pH 6, 75 +/- 2.7% of the initial COD (approximately 10,000 mg L(-1)), respectively. Interestingly, within 5 days, the pH in all inoculated bioreactors progressed toward pH 8. However, all abiotic control bioreactors remained at the pH at which they were amended. The fate of the inoculum, determined by denaturing gradient gel electrophoresis (DGGE) and by cluster analysis of the resulting DGGE profiles, revealed that the inocula survived throughout operation of all pH-amended bioreactors. Length-heterogeneity polymerase chain reaction (PCR) was used to track the population dynamics of individual strains. After 7 days of operation, M. esteraromaticum was the most abundant population in all bioreactors, regardless of pH. From our findings, it appears necessary to adjust the MWF wastewater from pH 9 to between 6 and 7, to achieve optimal biological treatment rates.

  4. WORK BASED HIGHER LEARNING FOR THE DANISH TOURISM SECTOR

    DEFF Research Database (Denmark)

    Lindegaard, Klaus; Voergård-Olesen, Rikke Karen

    2012-01-01

    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...... to be suitable for the tourism industry and needs to be developed within the higher education institutions in Denmark.......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...

  5. Collaborative work model based on peer-to-peer network

    Institute of Scientific and Technical Information of China (English)

    JIANG Jian-zhong; FU Li; ZHANG Xuan-peng; XU Chuan-yun

    2007-01-01

    In this paper, we incorporated peer-to-peer (P2P) concept with agent technology and put forward a collaborative work model based on peer-to-peer network (P2PCWM) after investigating into business demands of modern enterprises and problems prevailing in mainstream collaborative work systems based on central server. Theoretically, the P2PCWM can effectively overcome the problems in a conventional system with a central server and meet the practical demands of modern businesses. It is distinguished from other systems by its features of equality, openness, promptness, fairness, expandability and convenience.

  6. Seismic Analysis of Deep Water Pile Foundation Based on Three-Dimensional Potential-Based Fluid Elements

    Directory of Open Access Journals (Sweden)

    Kai Wei

    2013-01-01

    Full Text Available This paper investigates the use of three-dimensional (3D ϕ-u potential-based fluid elements for seismic analyses of deep water pile foundation. The mathematical derivations of the potential-based formulations are presented for reference. The potential-based modeling technique is studied and validated through experimental data and analytical solutions. Earthquake time history analyses for a 9-pile foundation in dry and different water environments are conducted, respectively. The seismic responses are discussed to investigate the complex effect of earthquake-induced fluid-structure interaction. Through the analyses, the potential-based fluid and interface elements are shown to perform adequately for the seismic analyses of pile foundation-water systems, and some interesting conclusions and recommendations are drawn.

  7. Two-phase working fluids for the temperature range 100-350 C. [in heat pipes for solar applications

    Science.gov (United States)

    Saaski, E. W.; Tower, L.

    1977-01-01

    The decomposition and corrosion of two-phase heat transfer liquids and metal envelopes have been investigated on the basis of molecular, bond strengths and chemical thermodynamics. Potentially stable heat transfer fluids for the temperature range 100 to 350 C have been identified, and reflux heat pipe tests initiated with 10 fluids and carbon steel and aluminum envelopes to experimentally establish corrosion behavior and noncondensable gas generation rates.

  8. Low-energy degassing mechanisms for a fluid-based radioxenon detection system

    Energy Technology Data Exchange (ETDEWEB)

    Russ, W.R.; Stuenkel, D.O.; Valentine, J.D. [Univ. of Cincinnati, OH (United States). Dept. of Mechanical, Industrial and Nuclear Engineering; Gross, K.C. [Argonne National Lab., IL (United States). Reactor Analysis Div.

    1998-09-01

    A method to concentrate heavy noble gases from the atmosphere using certain organic fluids is being developed. To use this technique in a system to monitor the atmosphere for important noble gas fission products (Xe-131, Xe-131m, Xe-133, Xe-133m, and Xe-135) generated by nuclear testing, the radionuclides captured in the fluid must either be detected in the fluid or degassed. This study presents experimental results for a number of possible degassing methods, including heating bubbling with a purge gas, ultrasonic agitation, vacuum, and combinations thereof. Methods were evaluated for energy and time requirements and dilution of the degas product. Initial experiments indicate that in addition to overcoming the standard desorption process dictated by partial pressures per Henry`s Law, a capture mechanism must also be overcome to degas. Some type of agitation, thermal or mechanical, can be used to release weakly trapped gas atoms from the fluid, while diffusional mass transfer can be enhanced through entrainment with a purge gas or use of a vacuum. Ultrasonic agitation of a thin film in a strong vacuum has been shown to be the most effective method of those tested. Implementation of an efficient degas system, along with an absorption system and radioxenon detector could result in an ultrasensitive fluid-based radioxenon measurement system that is more portable, less expensive, and simpler than charcoal-based systems which use cryogenic techniques.

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

    CERN Document Server

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

    2016-01-01

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

  10. When project-based management causes distress at work,

    OpenAIRE

    Asquin, Alain; Garel, Gilles; Picq, Thierry

    2009-01-01

    Project-based working is so widespread today that Luc Boltanski and Eve Chiapello (1999) go so far as to regard the project-based 'mode of justification' as a component part of the new ideology of modern capitalism. This particular set of principles is applied in the legal, educational, psychological, political and managerial spheres, which confirms Jean Pierre Boutinet's vision (Boutinet 1990) of the project as a pervasive element of social life. The injunctions to make commitments and the p...

  11. 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)

  12. Transesterification reaction for synthesis of palm-based ethylhexyl ester and formulation as base oil for synthetic drilling fluid.

    Science.gov (United States)

    Abdul Habib, Nor Saiful Hafiz; Yunus, Robiah; Rashid, Umer; Taufiq-Yap, Yun H; Abidin, Zurina Zainal; Syam, Azhari Muhammad; Irawan, Sonny

    2014-01-01

    The use of vegetable oil-based ester as a base fluid in synthetic drilling fluid has become a trend in drilling operations due to its environmental advantages. The transesterification reaction of palm oil methyl ester (POME) with 2-ethylhexanol (2EH) produced 98% of palm oil-based ethylhexyl ester in less than 30 minutes. Since the transesterification reaction of POME with 2EH is a reversible reaction, its kinetics was studied in the presence of excess EH and under vacuum. The POME-to-EH molar ratio and vacuum pressure were held constant at 1:2 and 1.5 mbar respectively and the effects of temperature (70 to 110°C) were investigated. Using excess of EH and continual withdrawal of methanol via vacuum promoted the reaction to complete in less than 10 minutes. The rate constant of the reaction (k) obtained from the kinetics study was in the range of 0.44 to 0.66 s⁻¹ and the activation energy was 15.6 kJ.mol⁻¹. The preliminary investigations on the lubrication properties of drilling mud formulated with palm oil-based 2EH ester indicated that the base oil has a great potential to substitute the synthetic ester-based oil for drilling fluid. Its high kinematic viscosity provides better lubrication to the drilling fluid compared to other ester-based oils. The pour point (-15°C) and flash point (204°C) values are superior for the drilling fluid formulation. The plastic viscosity, HPHT filtrate loss and emulsion stability of the drilling fluid had given acceptable values, while gel strength and yield point could be improved by blending it with proper additives.

  13. 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.

  14. Mobile Communication and Work Practices in Knowledge-based Organizations

    OpenAIRE

    Pertti Hurme

    2005-01-01

    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.

  15. Enhancing Social Work Education through Team-Based Learning

    Science.gov (United States)

    Gillespie, Judy

    2012-01-01

    Group learning strategies are used extensively in social work education, despite the challenges and negative outcomes regularly experienced by students and faculty. Building on principles of cooperative learning, team-based learning offers a more structured approach that maximizes the benefits of cooperative learning while also offering…

  16. Cutting Tools. Youth Training Scheme. Core Exemplar Work Based Project.

    Science.gov (United States)

    Further Education Staff Coll., Blagdon (England).

    This trainer's guide is intended to assist supervisors of work-based career training projects in teaching students to compare the performance of two different types of engineering cutting tools and to determine their cost-effectiveness and efficiency. The guide is one in a series of core curriculum modules that is intended for use in combination…

  17. 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 researc

  18. Social Work Students' Perceptions of Team-Based Learning

    Science.gov (United States)

    Macke, Caroline; Taylor, Jessica Averitt; Taylor, James E.; Tapp, Karen; Canfield, James

    2015-01-01

    This study sought to examine social work students' perceptions of Team-Based Learning (N = 154). Aside from looking at overall student perceptions, comparative analyses examined differences in perceptions between BSW and MSW students, and between Caucasian students and students of color. Findings for the overall sample revealed favorable…

  19. Employers' Approaches to Work-Based Training in Britain.

    Science.gov (United States)

    Hillage, Jim

    1996-01-01

    The British Labour Force Survey indicates that work-based training is skewed toward service sector occupations and high-level workers. Few employers have a formal or systematic training approach. Lower-skilled, more disadvantaged workers have the least access to education and training. (SK)

  20. Leadership for Nursing Work-Based Mobile Learning

    Science.gov (United States)

    Fahlman, Dorothy

    2016-01-01

    This paper reflects on work-based mobile learning in the Canadian healthcare system for registered nurses' ongoing skills development and continuing professional development. It calls on distributed leadership to address the organizational contextual factors for making this mode of learning sustainable. [For the full proceedings, see ED571335.

  1. 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…

  2. Hegemonic Power Process in Team-based Work

    NARCIS (Netherlands)

    Doorewaard, J.A.C.M.; Brouns, B.B.G.

    2003-01-01

    The purpose of this paper is to portray how implicit “hegemonic power processes” channel the way in which self-managing teams deal with organisational dilemmas. Hegemonic power processes in team-based work are, to a great extent concealed, processes of meaning and identity formation. These processes

  3. 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 con

  4. Novel optical devices based on the tunable refractive index of magnetic fluid and their characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yong, E-mail: zhaoyong@ise.neu.edu.cn [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China); Zhang Yuyan [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China); Shenyang Institute of Engineering, Shenyang 110136 (China); Lv Riqing; Wang Qi [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China)

    2011-12-15

    As a new type of functional material, magnetic fluid (MF) is a stable colloid of magnetic nanoparticles, dressed with surfactant and dispersed in the carrier liquid uniformly. The MF has many unique optical properties, and the most important one is its tunable refractive index property. This paper summarizes the properties of the MF refractive index and the related optical devices. The refractive index can be easily controlled by external magnetic field, temperature, and so on. But the tunable refractive index of MF has a relaxation effect. As a result, the response time is more than milliseconds and the MF is only suitable for low speed environment. Compared with the traditional optical devices, the magnetic fluid based optical devices have the tuning ability. Compared with the tunable optical devices (the electro-optic devices (LiNbO{sub 3}) of more than 10 GHz modulation speed, acoustic-optic devices (Ge) of more than 20 MHz modulation speed), the speed of the magnetic fluid based optical devices is low. Now there are many applications of magnetic fluid based on the refractive index in the field of optical information communication and sensing technology, such as tunable beam splitter, optical-fiber modulator, tunable optical gratings, tunable optical filter, optical logic device, tunable interferometer, and electromagnetic sensor. With the development of the research and application of magnetic fluid,a new method, structure and material to improve the response time can be found, which will play an important role in the fields of optical information communication and sensing technology. - Highlights: > Magnetic fluid is a new type of functional material, which has many unique optical properties. > We summarize the tunable refractive index property and the related optical devices. > Refractive index can be easily controlled by external magnetic field, temperature and so on. > There are many applications in the field of optical communication and sensing technology

  5. Nanoplugging Performance of Hyperbranched Polyamine as Nanoplugging Agent in Oil-Based Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Gang Xie

    2015-01-01

    Full Text Available A hyperbranched polyamine was synthesized by self-condensing vinyl polymerization with divinyl sulfone, N-phenyl-p-phenylenediamine, by A2 + BB2' approach. The hyperbranched polyamine was characterized by FT-IR, TGA, and phase analysis light scanning. Average grain diameter of hyperbranched polyamine was 36.7 nm. Hyperbranched polyamine has good thermal stability. Hyperbranched polyamine (HBPA was employed successfully as nanoplugging agent in oil-based drilling fluid system, which could plug nanopore formation in shale formation. HBPA has a little effect on rheological properties of oil-based drilling fluid and the FLAPI and FLHTHP decreased dramatically with an increase of hyperbranched polyamine. Emulsion-breaking voltage has a slight increase, which is beneficial to maintain stability of oil-based drilling fluid. When the HBPA concentration is greater than 1 wt%, plugging rate of oil-based drilling fluid for artificial core is close to 100% and the permeability recovery value can reach 99.7% after adding 1 wt% HBPA, which prove that HBPA has an excellent plugging performance.

  6. 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.

  7. Trajectory Prediction of Rotating Objects in Viscous Fluid: Based on Kinematic Investigation of Magnus Glider

    OpenAIRE

    Wei, Zhiyuan; Ding, Lijie; Wei, Kai; Wang,Ziwei; Dai, Rucheng

    2016-01-01

    The case of a rotating object traveling through viscous fluid appears in many phenomena like the banana ball and missile movement. In this work, we build a model to predict the trajectory of such rotating objects with near-cylinder geometry. The analytical expression of Magnus force is given and a wind tunnel experiment is carried out, which shows the Magnus force is well proportional to the product of angular velocity and centroid velocity. The trajectory prediction is consistent with the tr...

  8. 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.

  9. Ground-based activities in preparation of SELENE ISS experiment on self-rewetting fluids

    Science.gov (United States)

    Savino, R.; Abe, Y.; Castagnolo, D.; Celata, G. P.; Kabov, O.; Kawaji, M.; Sato, M.; Tanaka, K.; Thome, J. R.; Van Vaerenbergh, S.

    2011-12-01

    SELENE (SELf rewetting fluids for thermal ENErgy management) is a microgravity experiment proposed to the European Space Agency (ESA) in response to the Announcement of Opportunities for Physical Sciences. Main objectives of the microgravity research onboard ISS include the quantitative investigation of heat transfer performances of "self-rewetting fluids" and "nano self-rewetting fluids" in model heat pipes and validation of adequate theoretical and numerical modelling able to predict their behaviour in microgravity conditions. This article summarizes the results of ground-based research activities in preparation of the microgravity experiments. They include: 1) thermophysical properties measurements; 2) study of thermo-soluto-capillary effects in micro-channels; 3) numerical modelling; 4) thermal and concentration distribution measurements with optical (e.g. interferometric) and intrusive techniques; 5) surface tension-driven effects and thermal performances test on different capillary structures and heat pipes; 6) breadboards development and support to definition of scientific requirements.

  10. Guiding and confinement of interface acoustic waves in solid-fluid pillar-based phononic crystals

    Science.gov (United States)

    Razip Wee, M. F. Mohd; Addouche, Mahmoud; Siow, Kim S.; Zain, A. R. Md; Elayouch, Aliyasin; Chollet, Franck; Khelif, Abdelkrim

    2016-12-01

    Pillar-based phononic crystals exhibit some unique wave phenomena due to the interaction between surface acoustic modes of the substrate and local resonances supported by pillars. In this paper, we extend the investigations by taking into account the presence of a liquid medium. We particularly demonstrate that local resonances dramatically decrease the phase velocity of Scholte-Stoneley wave, which leads to a slow wave at the solid/fluid interface. Moreover, we show that increasing the height of pillars introduces a new set of branches of interface modes and drastically affects the acoustic energy localization. Indeed, while some modes display a highly confined pressure between pillars, others exponentially decay in the fluid or only propagate in the solid without disturbing the fluid pressure. These theoretical results, performed by finite element method, highlight a new acoustic wave confinement suitable in various applications such as acoustophoresis, lab on chip and microfluidics.

  11. 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.

  12. 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.

  13. 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

  14. Performance of Organic Rankine Cycle Using Zeotropic Working Fluids for Geothermal Utilization%地热源非共沸工质有机朗肯循环发电性能分析

    Institute of Scientific and Technical Information of China (English)

    郭丛; 杜小泽; 杨立军; 杨勇平

    2014-01-01

    建立有机朗肯循环热力学模型和蒸发器传热模型;基于工质的实验经验状态方程,利用REFPROP 8.0软件获得非共沸工质物性;以获得最佳的凝汽器温度匹配为原则选择工质。采用种温度的地热能,在给定的蒸发器和凝汽器夹点温差下,分析了采用组分比例为0.64:0.36的R600a/R601非共沸工质的有机朗肯循环发电系统的特性,并与R601纯工质发电循环进行了比较。结果表明:以对外输出功为目标函数的利用地热的中低温有机朗肯循环发电系统中不宜加入回热器;对于蒸发器热源进出口温差较小的工况,如热源来自水蒸气凝结放热,采用混合工质的循环的性能不如纯工质的;有机朗肯循环采用混合工质时其最大对外输出功要高于纯工质的,且热源温度越低时,这种优势越明显。%Thermodynamic model of organic Rankine cycle (ORC) and heat transfer model for evaporator were developed, and thermal properties for mixture working fluid were obtained by REFPROP 8.0 on the basis of the empirical equations of state. The selection principle for working fluids was based on the matching between working fluid and cooling water in the condenser. Geothermal energy in three heat source temperatures was simulated, and a zeotropic mixture, R600a/R601 with mole fraction 0.64/0.36, was used as the working fluid of ORC for power generation with the given pinch temperature for the evaporator and condenser. Its performance was analyzed and compared with that of pure working fluid, R601. The analytical results show that it is not suitable to introduce the internal heat exchanger (IHX) to the ORC system using medium or low temperature geothermal energy as heat source with work output as objective function. ORC system with pure working fluid has a better performance than that with mixture under the condition that temperature difference between inlet and outlet of heat source is small (i

  15. 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

  16. 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.

  17. Rock-fluid interaction and phase properties of fluids in nano- and subnano-pores of shales: Sorption-based studies

    Science.gov (United States)

    Kumar, Sanyog

    Sorption-based methodologies are proposed and developed to study rock-fluid interactions and properties of the fluid-phase in organic-rich shale reservoirs. Lack of appropriate methods to study these attributes of shale reservoirs affects the efficiency and economy of the shale-based exploration and production (E&P) efforts. A macroscopic conception of fluids still guides most existing methods for studying rock-fluid interaction and fluid phase properties. However, the modified regime of surface forces in fluids confined within nanometer and sub-nanometer sized pores typical of shales render such a macroscopic treatment fundamentally inconsistent. Apart from these theoretical limitations, shales are operationally challenging for the existing methods for rock-fluid interaction studies, primarily due to their ultra-low permeability, compositional heterogeneity, and the presence of organic matter and swelling clay minerals. Therefore, I propose using sorption-based methods that are sensitive to the modified regime of the surface forces in nano- and sub-nano-pores to study rock-fluid interaction and fluid-phase properties in shales. The Nitrogen adsorption method that is commonly used to study pore-structures was improvised in this thesis. In addition to nitrogen, water and hexane vapors were used to study rock-fluid interactions in organic-rich shales, which helped in quantifying the surface areas of the hydrophilic and hydrophobic pores of shales. In another study, the role of hydrophilic and hydrophobic pores in supercritical CO2 sorption was further investigated by measuring supercritical CO2 sorption isotherms for illite clay and organic-rich shale samples in dry and in water-imbibed conditions. In a separate study, ultrasonic p-wave measurements during sorption experiments allowed a determination of the phase properties of fluids confined in the nano- and sub-nanometer sized pores. BET specific surface areas (SSA) determined from the isotherms of water and hexane

  18. Work-based learning in health care environments.

    Science.gov (United States)

    Spouse, J

    2001-03-01

    In reviewing contemporary literature and theories about work-based learning, this paper explores recent trends promoting life-long learning. In the process the paper reviews and discusses some implications of implementing recent policies and fostering le arning in health care practice settings. Recent Government policies designed to provide quality health care services and to improve staffing levels in the nursing workforce, have emphasized the importance of life-long learning whilst learning-on-the-job and the need to recognize and credit experiential learning. Such calls include negotiation of personal development plans tailored to individual educational need and context-sensitive learning activities. To be implemented effectively, this policy cann ot be seen as a cheap option but requires considerable financial resourcing for preparation of staff and the conduct of such activities. Successful work-based learning requires investment in staff at all levels as well as changes to staffing structures in organizations and trusts; changes designed to free people up to work and learn collaboratively. Creating an organizational environment where learning is prized depends upon a climate of trust; a climate where investigation and speculation are fostered and where time is protected for engaging in discussions about practice. Such a change may be radical for many health care organizations and may require a review of current policies and practices ensuring that they include education at all levels. The nature of such education also requires reconceptualizing. In the past, learning in practice settings was seen as formal lecturing or demonstration, and relied upon behaviourist principles of learning. Contemporary thinking suggests effective learning in work-settings is multi-faceted and draws on previously acquired formal knowledge, contextualizes it and moulds it according to situations at hand. Thinking about work-based learning in this way raises questions about how such

  19. 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.

  20. Students’ Self-Assessment in Project-Based Work

    Directory of Open Access Journals (Sweden)

    Alvyda Liuolienė

    2014-12-01

    Full Text Available The article aims at exploring the benefits of self-assessment as it is an important skill for lifelong learning and for critical reflection on one’s own performance. The authors of the article focus on students’ self-assessment of their language proficiency skills and achievements in working on projects. Students’ reflection on their learning has numerous benefits, such as motivation, self-direction, greater responsibility, decreased intimidation and fear of the audience, development of critical thinking, etc. The paper presents the analysis of a questionnaire based on the research of respondents’ self-evaluation of working on the project. The study has aimed at finding out the students’ attitude towards project-based learning and their assessment of their personal progress in respect of the development of their language proficiency skills.

  1. 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.

  2. Micromachined Fluid Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Shiqiang Liu

    2017-02-01

    Full Text Available Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, the fluid inertial sensors use a fluid instead of a solid proof mass as the moving and sensitive element, and thus offer advantages of simple structures, low cost, high shock resistance, and large measurement ranges while the sensitivity and bandwidth are not competitive. Many studies and various designs have been reported in the past two decades. This review firstly introduces the working principles of fluid inertial sensors, followed by the relevant research developments. The micromachined thermal accelerometers based on thermal convection have developed maturely and become commercialized. However, the micromachined fluid gyroscopes, which are based on jet flow or thermal flow, are less mature. The key issues and technologies of the thermal accelerometers, mainly including bandwidth, temperature compensation, monolithic integration of tri-axis accelerometers and strategies for high production yields are also summarized and discussed. For the micromachined fluid gyroscopes, improving integration and sensitivity, reducing thermal errors and cross coupling errors are the issues of most concern.

  3. A new miniaturized engine based on thermomagnetic effect of magnetic fluids

    Institute of Scientific and Technical Information of China (English)

    Lujun ZHOU; Yimin XUAN; Qiang LI; Wenlei LIAN

    2009-01-01

    A new engine system, essentially consisting of a permanent NdFeB magnet, a kerosene-based magnetic fluid and a rotor, is proposed based on the thermomagnetic effect of a temperature-sensitive magnetic fluid. The rotor was driven by the thermal convection of the magnetic fluid in the presence of a homogeneous external magnetic field. A digital camera was used to record the rotation speed of the rotor to investigate the performance of the engine system under varying conditions such as heat load, heat sink temperature, and magnetic field distribution. The peak angle velocity obtained for the rotor was about 2.1 rad/min. The results illustrate that the rotation speed of the rotor increases as the input heat load increases, or as the heat sink temperature decreases. The performance of the motor is considerably influenced by the magnetic field imposed. Therefore, the performance of such an engine can be controlled conveniently by changing the external magnetic field and/or the temperature distribution in the fluid.

  4. 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.

  5. Device modeling of superconductor transition edge sensors based on the two-fluid theory

    CERN Document Server

    Wang, Tian-Shun; Zhu, Qing-Feng; Wang, Jun-Xian; Li, Tie-Fu; Liu, Jian-She; Chen, Wei; Zhou, Xingxiang

    2012-01-01

    In order to support the design and study of sophisticated large scale transition edge sensor (TES) circuits, we use basic SPICE elements to develop device models for TESs based on the superfluid-normal fluid theory. In contrast to previous studies, our device model is not limited to small signal simulation, and it relies only on device parameters that have clear physical meaning and can be easily measured. We integrate the device models in design kits based on powerful EDA tools such as CADENCE and OrCAD, and use them for versatile simulations of TES circuits. Comparing our simulation results with published experimental data, we find good agreement which suggests that device models based on the two-fluid theory can be used to predict the behavior of TES circuits reliably and hence they are valuable for assisting the design of sophisticated TES circuits.

  6. Characterization and Testing of Novel Two-Phase Working Fluids for Spacecraft Thermal Management Operating Between 300 Deg. C and 400 Deg. C.

    Science.gov (United States)

    1994-12-01

    Determining the Pure Component Parameters in the Redlich - Kwong -Soave Equation of State," Chemical Engineering Science, 35, 1725, 1980. 100 80. J.M...suitability for this application . Extensive literature reviews, thermophysical property surveys, and surveys of compound availability on the aromatic...and testing of novel two-phase working fluids for spacecraft thermal management applications between 300’C and 400"C. The main application of these

  7. 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.

  8. 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.

  9. [Identification of transmission fluid based on NIR spectroscopy by combining sparse representation method with manifold learning].

    Science.gov (United States)

    Jiang, Lu-Lu; Luo, Mei-Fu; Zhang, Yu; Yu, Xin-Jie; Kong, Wen-Wen; Liu, Fei

    2014-01-01

    An identification method based on sparse representation (SR) combined with autoencoder network (AN) manifold learning was proposed for discriminating the varieties of transmission fluid by using near infrared (NIR) spectroscopy technology. NIR transmittance spectra from 600 to 1 800 nm were collected from 300 transmission fluid samples of five varieties (each variety consists of 60 samples). For each variety, 30 samples were randomly selected as training set (totally 150 samples), and the rest 30 ones as testing set (totally 150 samples). Autoencoder network manifold learning was applied to obtain the characteristic information in the 600-1800 nm spectra and the number of characteristics was reduced to 10. Principal component analysis (PCA) was applied to extract several relevant variables to represent the useful information of spectral variables. All of the training samples made up a data dictionary of the sparse representation (SR). Then the transmission fluid variety identification problem was reduced to the problem as how to represent the testing samples from the data dictionary (training samples data). The identification result thus could be achieved by solving the L-1 norm-based optimization problem. We compared the effectiveness of the proposed method with that of linear discriminant analysis (LDA), least squares support vector machine (LS-SVM) and sparse representation (SR) using the relevant variables selected by principal component analysis (PCA) and AN. Experimental results demonstrated that the overall identification accuracy of the proposed method for the five transmission fluid varieties was 97.33% by AN-SR, which was significantly higher than that of LDA or LS-SVM. Therefore, the proposed method can provide a new effective method for identification of transmission fluid variety.

  10. 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.

  11. 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.

  12. Environmental Beneficiation of Machining Wastes-Part III: Effects of Metal Working Fluids on the Spontaneous Heating of Machining Swarf.

    Science.gov (United States)

    Kawatra, S Komar; Hess, Mathew J

    1999-05-01

    Machining swarf is a finely divided metal powder that is prone to spontaneous heating and, in some cases, spontaneous combustion. The fine particle size, large amount of particle surface area, and the presence of moisture all promote rapid oxidation. This hazard dramatically increases disposal costs for swarf and interferes with recycling efforts. A potential method for minimizing spontaneous heating and facilitating recycling of the swarf is to spray a fluid on the material that coats the particles and creates a barrier between the metal and oxygen. Surface coatings could be tested for their effects on the spontaneous heating potential of swarf by treating a sample of swarf with a fluid that would coat the particles, then monitoring its heating behavior. This paper describes the results of applying corrosion inhibitors and machining fluids to the swarf, and monitoring the spontaneous heating behavior using a testing method developed specifically for this purpose. The effects of different types of surfactants and the effects of surfactant concentration on the spontaneous heating of swarf are discussed.

  13. Functional assessment of cerebral artery stenosis: A pilot study based on computational fluid dynamics.

    Science.gov (United States)

    Liu, Jia; Yan, Zhengzheng; Pu, Yuehua; Shiu, Wen-Shin; Wu, Jianhuang; Chen, Rongliang; Leng, Xinyi; Qin, Haiqiang; Liu, Xin; Jia, Baixue; Song, Ligang; Wang, Yilong; Miao, Zhongrong; Wang, Yongjun; Liu, Liping; Cai, Xiao-Chuan

    2016-10-04

    The fractional pressure ratio is introduced to quantitatively assess the hemodynamic significance of severe intracranial stenosis. A computational fluid dynamics-based method is proposed to non-invasively compute the FPRCFD and compared against fractional pressure ratio measured by an invasive technique. Eleven patients with severe intracranial stenosis considered for endovascular intervention were recruited and an invasive procedure was performed to measure the distal and the aortic pressure (Pd and Pa). The fractional pressure ratio was calculated as [Formula: see text] The computed tomography angiography was used to reconstruct three-dimensional (3D) arteries for each patient. Cerebral hemodynamics was then computed for the arteries using a mathematical model governed by Navier-Stokes equations and with the outflow conditions imposed by a model of distal resistance and compliance. The non-invasive [Formula: see text], [Formula: see text], and FPRCFD were then obtained from the computational fluid dynamics calculation using a 16-core parallel computer. The invasive and non-invasive parameters were tested by statistical analysis. For this group of patients, the computational fluid dynamics method achieved comparable results with the invasive measurements. The fractional pressure ratio and FPRCFD are very close and highly correlated, but not linearly proportional, with the percentage of stenosis. The proposed computational fluid dynamics method can potentially be useful in assessing the functional alteration of cerebral stenosis.

  14. Working cycles of devices based on bistable carbon nanotubes

    Science.gov (United States)

    Shklyaev, Oleg; Mockensturm, Eric; Crespi, Vincent; Carbon Nanotubes Collaboration

    2013-03-01

    Shape-changing nanotubes are an example of variable-shape sp2 carbon-based systems where the competition between strain and surface energies can be moderated by an externally controllable stimuli such as applied voltage, temperature, or pressure of gas encapsulated inside the tube. Using any of these stimuli one can transition a bistable carbon nanotube between the collapsed and inflated states and thus perform mechanical work. During the working cycle of such a device, energy from an electric or heat source is transferred to mechanical energy. Combinations of these stimuli allow the system to convert energy between different sources using the bistable shape-changing tube as a mediator. For example, coupling a bistable carbon nanotube to the heat and charge reservoirs can enable energy transfer between heat and electric forms. The developed theory can be extended to other nano-systems which change configurations in response to external stimuli.

  15. Analysis of the Properties of Working Substances for the Organic Rankine Cycle based Database "REFPROP"

    Science.gov (United States)

    Galashov, Nikolay; Tsibulskiy, Svyatoslav; Serova, Tatiana

    2016-02-01

    The object of the study are substances that are used as a working fluid in systems operating on the basis of an organic Rankine cycle. The purpose of research is to find substances with the best thermodynamic, thermal and environmental properties. Research conducted on the basis of the analysis of thermodynamic and thermal properties of substances from the base "REFPROP" and with the help of numerical simulation of combined-cycle plant utilization triple cycle, where the lower cycle is an organic Rankine cycle. Base "REFPROP" describes and allows to calculate the thermodynamic and thermophysical parameters of most of the main substances used in production processes. On the basis of scientific publications on the use of working fluids in an organic Rankine cycle analysis were selected ozone-friendly low-boiling substances: ammonia, butane, pentane and Freon: R134a, R152a, R236fa and R245fa. For these substances have been identified and tabulated molecular weight, temperature of the triple point, boiling point, at atmospheric pressure, the parameters of the critical point, the value of the derivative of the temperature on the entropy of the saturated vapor line and the potential ozone depletion and global warming. It was also identified and tabulated thermodynamic and thermophysical parameters of the steam and liquid substances in a state of saturation at a temperature of 15 °C. This temperature is adopted as the minimum temperature of heat removal in the Rankine cycle when working on the water. Studies have shown that the best thermodynamic, thermal and environmental properties of the considered substances are pentane, butane and R245fa. For a more thorough analysis based on a gas turbine plant NK-36ST it has developed a mathematical model of combined cycle gas turbine (CCGT) triple cycle, where the lower cycle is an organic Rankine cycle, and is used as the air cooler condenser. Air condenser allows stating material at a temperature below 0 °C. Calculation of the

  16. FLUID-BASED SIMULATION APPROACH FOR HIGH VOLUME CONVEYOR TRANSPORTATION SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Ying WANG; Chen ZHOU

    2004-01-01

    High volume conveyor systems in distribution centers have very large footprint and can handle large volumes and hold thousands of items. Traditional discrete-event cell-based approach to simulate such networks becomes computationally challenging. An alternative approach, in which the traffic is represented by segments of fluid flow of different density instead of individual packages, is presented in this paper to address this challenge. The proposed fluid-based simulation approach is developed using a Hybrid Petri Nets framework. The underlying model is a combination of an extension of a Batches Petri Nets (BPN) and a Stochastic Petri Nets (SPN). The extensions are in the inclusion of random elements and relaxation of certain structural constraints. Some adaptations are also made to fit the target system modeling. The approach is presented with an example.

  17. Computational Fluid Dynamics-Based Design Optimization Method for Archimedes Screw Blood Pumps.

    Science.gov (United States)

    Yu, Hai; Janiga, Gábor; Thévenin, Dominique

    2016-04-01

    An optimization method suitable for improving the performance of Archimedes screw axial rotary blood pumps is described in the present article. In order to achieve a more robust design and to save computational resources, this method combines the advantages of the established pump design theory with modern computer-aided, computational fluid dynamics (CFD)-based design optimization (CFD-O) relying on evolutionary algorithms and computational fluid dynamics. The main purposes of this project are to: (i) integrate pump design theory within the already existing CFD-based optimization; (ii) demonstrate that the resulting procedure is suitable for optimizing an Archimedes screw blood pump in terms of efficiency. Results obtained in this study demonstrate that the developed tool is able to meet both objectives. Finally, the resulting level of hemolysis can be numerically assessed for the optimal design, as hemolysis is an issue of overwhelming importance for blood pumps.

  18. Static characteristics design of hydrostatic guide-ways based on fluid-structure interactions

    Science.gov (United States)

    Lin, Shuo; Yin, YueHong

    2016-10-01

    With the raising requirements in micro optical systems, the available machines become hard to achieve the process dynamic and accuracy in all aspects. This makes compact design based on fluid/structure interactions (FSI) important. However, there is a difficulty in studying FSI with oil film as fluid domain. This paper aims at static characteristic design of a hydrostatic guide-way with capillary restrictors based on FSI. The pressure distribution of the oil film land is calculated by solving the Reynolds-equation with Galerkin technique. The deformation of structure is calculated by commercial FEM software, MSC. Nastran. A matlab program is designed to realize the coupling progress by modifying the load boundary in the submitting file and reading the deformation result. It's obvious that the stiffness of the hydrostatic bearing decreases with the weakening of the bearing structure. This program is proposed to make more precise prediction of bearing stiffness.

  19. Repository-Based Software Engineering Program: Working Program Management Plan

    Science.gov (United States)

    1993-01-01

    Repository-Based Software Engineering Program (RBSE) is a National Aeronautics and Space Administration (NASA) sponsored program dedicated to introducing and supporting common, effective approaches to software engineering practices. The process of conceiving, designing, building, and maintaining software systems by using existing software assets that are stored in a specialized operational reuse library or repository, accessible to system designers, is the foundation of the program. In addition to operating a software repository, RBSE promotes (1) software engineering technology transfer, (2) academic and instructional support of reuse programs, (3) the use of common software engineering standards and practices, (4) software reuse technology research, and (5) interoperability between reuse libraries. This Program Management Plan (PMP) is intended to communicate program goals and objectives, describe major work areas, and define a management report and control process. This process will assist the Program Manager, University of Houston at Clear Lake (UHCL) in tracking work progress and describing major program activities to NASA management. The goal of this PMP is to make managing the RBSE program a relatively easy process that improves the work of all team members. The PMP describes work areas addressed and work efforts being accomplished by the program; however, it is not intended as a complete description of the program. Its focus is on providing management tools and management processes for monitoring, evaluating, and administering the program; and it includes schedules for charting milestones and deliveries of program products. The PMP was developed by soliciting and obtaining guidance from appropriate program participants, analyzing program management guidance, and reviewing related program management documents.

  20. Magnetic investigation of zero-field-cooled dextran-coated magnetite-based magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Morais, P.C. [Universidade de Brasilia, Instituto de Fisica, Fisica Aplicada, C.P. 004455, Campus Universitario, Brasilia-DF 70919 970 (Brazil)]. E-mail: pcmor@unb.br; Santos, J.G. [Universidade de Brasilia, Instituto de Fisica, Fisica Aplicada, C.P. 004455, Campus Universitario, Brasilia-DF 70919 970 (Brazil); Silveira, L.B. [Universidade de Brasilia, Instituto de Fisica, Fisica Aplicada, C.P. 004455, Campus Universitario, Brasilia-DF 70919 970 (Brazil); Nunes, W.C. [Universidade Federal doRio de Janeiro, Instituto de Fisica, 21945-970, Rio de Janeiro-RJ (Brazil); Sinnecker, J.P. [Universidade Federal doRio de Janeiro, Instituto de Fisica, 21945-970, Rio de Janeiro-RJ (Brazil); Novak, M.A. [Universidade Federal doRio de Janeiro, Instituto de Fisica, 21945-970, Rio de Janeiro-RJ (Brazil)

    2005-03-15

    In this study, we investigate the temperature dependence of the zero-field-cooled magnetization of a quasi-monodisperse dextran-coated magnetite-based magnetic fluid. The well-defined maximum in the magnetization versus temperature curve and its downshift with the applied external field is explained by a simple model considering thermally activated dynamics of the nanoparticles magnetic moment and the temperature dependence of the saturation magnetization.

  1. Fluid Sensor Based on Transmission Dip Caused by Mini Stop-Band in Photonic Crystal Slab

    Institute of Scientific and Technical Information of China (English)

    CAO Lei; HUANG Yi-Dong; MAO Xiao-Yu; LI Fei; ZHANG Wei; PENG Jiang-De

    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.

  2. Preparation of water-soluble nanographite and its application in water-based cutting fluid

    Science.gov (United States)

    Chen, Qiang; Wang, Xue; Wang, Zongting; Liu, Yu; You, Tingzheng

    2013-01-01

    Water-soluble nanographite was prepared by in situ emulsion polymerization using methacrylate as polymeric monomer. The dispersion stability and dispersion state of graphite particles were evaluated by UV-visible spectrophotometry and scanning electron microscopy, respectively. The water-soluble nanographite was then added into the water-based cutting fluid as lubricant additive. The lubrication performance of water-based cutting fluid with the nanographite additive was studied on four-ball friction tester and surface tensiometer. Results indicate that the modification method of in situ emulsion polymerization realizes the uniform and stabilized dispersion of nanographite in aqueous environment. The optimal polymerization condition is 70°C (polymerization temperature) and 5 h (polymerization time). The addition of nanographite decreases the friction coefficient and wear scar diameter by 44% and 49%. Meanwhile, the maximum non-seizure load ( P B ) increases from 784 to 883 N, and the value of surface tension (32.76 × 10-3 N/m) is at low level. Nanographite additive improves apparently the lubrication performance of water-based cutting fluid.

  3. UAV feasible path planning based on disturbed fluid and trajectory propagation

    Directory of Open Access Journals (Sweden)

    Yao Peng

    2015-08-01

    Full Text Available In this paper, a novel algorithm based on disturbed fluid and trajectory propagation is developed to solve the three-dimensional (3-D path planning problem of unmanned aerial vehicle (UAV in static environment. Firstly, inspired by the phenomenon of streamlines avoiding obstacles, the algorithm based on disturbed fluid is developed and broadened. The effect of obstacles on original fluid field is quantified by the perturbation matrix, where the tangential matrix is first introduced. By modifying the original flow field, the modified one is then obtained, where the streamlines can be regarded as planned paths. And the path proves to avoid all obstacles smoothly and swiftly, follow the shape of obstacles effectively and reach the destination eventually. Then, by considering the kinematics and dynamics equations of UAV, the method called trajectory propagation is adopted to judge the feasibility of the path. If the planned path is unfeasible, repulsive and tangential parameters in the perturbation matrix will be adjusted adaptively based on the resolved state variables of UAV. In most cases, a flyable path can be obtained eventually. Simulation results demonstrate the effectiveness of this method.

  4. Rheological properties of oil-based drilling fluids at high temperature and high pressure

    Institute of Scientific and Technical Information of China (English)

    赵胜英; 鄢捷年; 舒勇; 张洪霞

    2008-01-01

    The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental results show that the apparent viscosity,plastic viscosity and yield point decrease with the increase of temperature,and increase with the increase of pressure.The effect of pressure on the apparent viscosity,plastic viscosity and yield point is considerable at ambient temperature.However,this effect gradually reduces with the increase of temperature.The major factor influencing the rheological properties of oil-based drilling fluids is temperature instead of pressure in the deep sections of oil wells.On the basis of numerous experiments,the model for predict the apparent viscosity,plastic viscosity and yield point of oil-based drilling fluids at high temperature and pressure was established using the method of regressive analysis.It is confirmed that the calculated data are in good agreement with the measured data,and the correlation coefficients are more than 0.98.The model is convenient for use and suitable for the application in drilling operations.

  5. Three-dimensional path planning for unmanned aerial vehicle based on interfered fluid dynamical system

    Directory of Open Access Journals (Sweden)

    Wang Honglun

    2015-02-01

    Full Text Available This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle (UAV in complex terrain based on interfered fluid dynamical system (IFDS and the theory of obstacle avoidance by the flowing stream. With no requirement of solutions to fluid equations under complex boundary conditions, the proposed method is suitable for situations with complex terrain and different shapes of obstacles. Firstly, by transforming the mountains, radar and anti-aircraft fire in complex terrain into cylindrical, conical, spherical, parallelepiped obstacles and their combinations, the 3D low-flying path planning problem is turned into solving streamlines for obstacle avoidance by fluid flow. Secondly, on the basis of a unified mathematical expression of typical obstacle shapes including sphere, cylinder, cone and parallelepiped, the modulation matrix for interfered fluid dynamical system is constructed and 3D streamlines around a single obstacle are obtained. Solutions to streamlines with multiple obstacles are then derived using weighted average of the velocity field. Thirdly, extra control force method and virtual obstacle method are proposed to deal with the stagnation point and the case of obstacles’ overlapping respectively. Finally, taking path length and flight height as sub-goals, genetic algorithm (GA is used to obtain optimal 3D path under the maneuverability constraints of the UAV. Simulation results show that the environmental modeling is simple and the path is smooth and suitable for UAV. Theoretical proof is also presented to show that the proposed method has no effect on the characteristics of fluid avoiding obstacles.

  6. Three-dimensional path planning for unmanned aerial vehicle based on interfered fluid dynamical system

    Institute of Scientific and Technical Information of China (English)

    Wang Honglun; Lyu Wentao; Yao Peng; Liang Xiao; Liu Chang

    2015-01-01

    This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle (UAV) in complex terrain based on interfered fluid dynamical system (IFDS) and the theory of obstacle avoidance by the flowing stream. With no requirement of solutions to fluid equations under complex boundary conditions, the proposed method is suitable for situations with complex terrain and different shapes of obstacles. Firstly, by transforming the mountains, radar and anti-aircraft fire in complex terrain into cylindrical, conical, spherical, parallelepiped obstacles and their combinations, the 3D low-flying path planning problem is turned into solving streamlines for obstacle avoidance by fluid flow. Secondly, on the basis of a unified mathematical expression of typical obstacle shapes including sphere, cylinder, cone and parallelepiped, the modulation matrix for interfered fluid dynamical system is constructed and 3D streamlines around a single obstacle are obtained. Solutions to streamlines with multiple obstacles are then derived using weighted average of the velocity field. Thirdly, extra control force method and virtual obstacle method are proposed to deal with the stagnation point and the case of obstacles’ overlapping respectively. Finally, taking path length and flight height as sub-goals, genetic algorithm (GA) is used to obtain optimal 3D path under the maneuverability constraints of the UAV. Simulation results show that the environmental modeling is simple and the path is smooth and suitable for UAV. Theoretical proof is also presented to show that the proposed method has no effect on the characteristics of fluid avoiding obstacles.

  7. Analogy between gambling and measurement-based work extraction

    Science.gov (United States)

    Vinkler, Dror A.; Permuter, Haim H.; Merhav, Neri

    2016-04-01

    In information theory, one area of interest is gambling, where mutual information characterizes the maximal gain in wealth growth rate due to knowledge of side information; the betting strategy that achieves this maximum is named the Kelly strategy. In the field of physics, it was recently shown that mutual information can characterize the maximal amount of work that can be extracted from a single heat bath using measurement-based control protocols, i.e. using ‘information engines’. However, to the best of our knowledge, no relation between gambling and information engines has been presented before. In this paper, we briefly review the two concepts and then demonstrate an analogy between gambling, where bits are converted into wealth, and information engines, where bits representing measurements are converted into energy. From this analogy follows an extension of gambling to the continuous-valued case, which is shown to be useful for investments in currency exchange rates or in the stock market using options. Moreover, the analogy enables us to use well-known methods and results from one field to solve problems in the other. We present three such cases: maximum work extraction when the probability distributions governing the system and measurements are unknown, work extraction when some energy is lost in each cycle, e.g. due to friction, and an analysis of systems with memory. In all three cases, the analogy enables us to use known results in order to obtain new ones.

  8. Fluid dynamics of heart valves during atrial fibrillation: a lumped parameter-based approach

    CERN Document Server

    Scarsoglio, Stefania; Guala, Andrea; Ridolfi, Luca

    2015-01-01

    Atrial fibrillation (AF) consequences on the heart valve dynamics are usually studied along with a valvular disfunction or disease, since in medical monitoring the two pathologies are often concomitant. Aim of the present work is to study, through a stochastic lumped-parameter approach, the basic fluid dynamics variations of heart valves, when only paroxysmal AF is present with respect to the normal sinus rhythm (NSR) in absence of any valvular pathology. Among the most common parameters interpreting the valvular function, the most useful turns out to be the regurgitant volume. During AF both atrial valves do not seem to worsen their performance, while the ventricular efficiency is remarkably reduced.

  9. Improving cooling devices for the hot face of Peltier pellets based on phase change fluids

    Energy Technology Data Exchange (ETDEWEB)

    Esarte, J. [Centros Tecnologicos de Navarra, Poligono Industrial Noain, 31009 Navarra (Spain); Blanco, J.M.; Mendia, F. [Depto. Maquinas y Motores Termicos, Universidad del Pais Vasco/EHU, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Pena, F. [Iberdrola Generacion, Bahia de Santurce, 48009 Vizcaya (Spain)

    2006-07-15

    The thermoelectricity has not suffered any important progress for the last twenty years, owed mainly to the low efficiency of the heat sinks, because the Peltier pellet provides a high calorific power across a small surface. In this paper a deep study of the fin cooling for Peltier pellets, has been carried out, by means of both an experimental model and also through computational fluid dynamics. A phase change device called thermosyphon has also been designed and optimized, which allows to uniform the heat flow, decreasing in this way the pellet thermal resistance. The work focuses on its hot face and leaves for another study the cold face optimization. (author)

  10. Trajectory Prediction of Rotating Objects in Viscous Fluid: Based on Kinematic Investigation of Magnus Glider

    CERN Document Server

    Wei, Zhiyuan; Wei, Kai; Wang, Ziwei; Dai, Rucheng

    2016-01-01

    The case of a rotating object traveling through viscous fluid appears in many phenomena like the banana ball and missile movement. In this work, we build a model to predict the trajectory of such rotating objects with near-cylinder geometry. The analytical expression of Magnus force is given and a wind tunnel experiment is carried out, which shows the Magnus force is well proportional to the product of angular velocity and centroid velocity. The trajectory prediction is consistent with the trajectory record experiment of Magnus glider, which implies the validity and robustness of this model.

  11. Fluid dynamics of heart valves during atrial fibrillation: a lumped parameter-based approach.

    Science.gov (United States)

    Scarsoglio, S; Camporeale, C; Guala, A; Ridolfi, L

    2016-01-01

    Atrial fibrillation (AF) consequences on the heart valve dynamics are usually studied along with a valvular disfunction or disease, since in medical monitoring, the two pathologies are often concomitant. Aim of the present work is to study, through a stochastic lumped-parameter approach, the basic fluid dynamics variations of heart valves, when only paroxysmal AF is present with respect to the normal sinus rhythm in absence of any valvular pathology. Among the most common parameters interpreting the valvular function, the most useful turns out to be the regurgitant volume. During AF, both atrial valves do not seem to worsen their performance, while the ventricular efficiency is remarkably reduced.

  12. Computational Fluid Dynamics Based Investigation of Sensitivity of Furnace Operational Conditions to Burner Flow Controls

    Energy Technology Data Exchange (ETDEWEB)

    Marc Cremer; Kirsi St. Marie; Dave Wang

    2003-04-30

    This is the first Semiannual Technical Report for DOE Cooperative Agreement No: DE-FC26-02NT41580. The goal of this project is to systematically assess the sensitivity of furnace operational conditions to burner air and fuel flows in coal fired utility boilers. Our approach is to utilize existing baseline furnace models that have been constructed using Reaction Engineering International's (REI) computational fluid dynamics (CFD) software. Using CFD analyses provides the ability to carry out a carefully controlled virtual experiment to characterize the sensitivity of NOx emissions, unburned carbon (UBC), furnace exit CO (FECO), furnace exit temperature (FEGT), and waterwall deposition to burner flow controls. The Electric Power Research Institute (EPRI) is providing co-funding for this program, and instrument and controls experts from EPRI's Instrument and Controls (I&C) Center are active participants in this project. This program contains multiple tasks and good progress is being made on all fronts. A project kickoff meeting was held in conjunction with NETL's 2002 Sensors and Control Program Portfolio Review and Roadmapping Workshop, in Pittsburgh, PA during October 15-16, 2002. Dr. Marc Cremer, REI, and Dr. Paul Wolff, EPRI I&C, both attended and met with the project COR, Susan Maley. Following the review of REI's database of wall-fired coal units, the project team selected a front wall fired 150 MW unit with a Riley Low NOx firing system including overfire air for evaluation. In addition, a test matrix outlining approximately 25 simulations involving variations in burner secondary air flows, and coal and primary air flows was constructed. During the reporting period, twenty-two simulations have been completed, summarized, and tabulated for sensitivity analysis. Based on these results, the team is developing a suitable approach for quantifying the sensitivity coefficients associated with the parametric tests. Some of the results of the CFD

  13. Analysis of the Turbulent Flow of Nanofluid Containing Ethylene Glycol and Water Base Fluid by using the Fluent Model

    Directory of Open Access Journals (Sweden)

    Ata Salari

    2016-12-01

    Full Text Available Given that the use of nano-fluids has increased in heat exchangers and since the flow regime in heat exchangers is often turbulent, justifying the effectiveness of using nano-fluids requires studying the nano-fluids turbulent flow. Analysis of nano-fluids steady flow, containing water-based fluid and aluminum oxide nanoparticles AR, AF and AK, has performed in developing and fully developed turbulent flow, in the pipe with a diameter of 150 mm and a length of 30 m by Gambit and Fluent software. After examining the independence of numerical results from the network, the results of numerical modeling were compared with the experimental results and given the consistency of numerical results with existing relationships; created model was used to study the nano-fluids flow. In this study, the impact of the type of nanoparticles on the parameters of nano-fluids flow in turbulent flow regime has been thoroughly investigated. in case of using ethylene glycol in the nano-fluid suspension, it might be because it has the pressure drop of 1437 Newton per meter squared, the shear stress of 0.74428 Pascal, the friction coefficient of 0.0415804 and the viscous drag force of the pipe wall of 24.884367 Newton due to having higher viscosity. Therefore, out of the two reviewed base fluids, water is economically preferred in the nanofluid suspension.

  14. 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.

  15. Tribological performances of multilayer-MoS2 nanoparticles in water-based lubricating fluid

    Science.gov (United States)

    Zhang, B. M.; Sun, J. L.

    2017-03-01

    Multilayer-MoS2 nanoparticles were dispersed in water-based lubricating fluid in a convenient and economical way. Oleic acid and triethanolamine were used as the main surfactants in this solution. Tribological performances of this fluid were tested under high pressure and high rotating speed. FEI Tecnai G20 TEM, Malvern Zetasizer Nano ZS were used to study the particle size and Zeta potential of the lubricants. Tribological performances of this water system with multilayer-MoS2 nanoparticles and the 3D-surfaces of wear scars after the experiments were analyzed by means of four-ball wear test machine and Olympus laser confocal microscope. According to Hertz theory and experimental data, it is practical significance to combine MoS2 nanoparticles with water-based lubricating fluid. Under high loading and high rotating speed the mixed suspension can provide good lubricating properties. On the basis of calculation the binding energy of layers in MoS2 nanoparticles is less than the energy of shearing in friction pairs. The layers in MoS2 nanoparticles slide in the process of friction. The best lubrication effects can be displayed when friction process lasts about 500 s.

  16. Thermodynamic Properties of Hard-Sphere Fluid under Confined Condition Based on Bridge Density Function

    Institute of Scientific and Technical Information of China (English)

    周世琦

    2003-01-01

    Based on the functional integral procedure, a recently proposed bridge density function [J. Chem. Phys. 112 (2000) 8079] is developed to calculate global thermodynamic properties of non-uniform fluids. The resulting surface tension of a hard wall-hard sphere interface as a function of the bulk hard sphere fluid density is in good agreement with the available simulation data. The proposed numerical procedure from the approximation of non-uniform first=order direct correlation function to a non=uniform system with excess Helmholtz free energy is of fundamental importance for phase behaviour under the confined condition due to the fact that many available simple approximations in classical density functional theory are for non=uniform first=order direct correlation function.

  17. 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.

  18. Spike-based population coding and working memory.

    Directory of Open Access Journals (Sweden)

    Martin Boerlin

    2011-02-01

    Full Text Available Compelling behavioral evidence suggests that humans can make optimal decisions despite the uncertainty inherent in perceptual or motor tasks. A key question in neuroscience is how populations of spiking neurons can implement such probabilistic computations. In this article, we develop a comprehensive framework for optimal, spike-based sensory integration and working memory in a dynamic environment. We propose that probability distributions are inferred spike-per-spike in recurrently connected networks of integrate-and-fire neurons. As a result, these networks can combine sensory cues optimally, track the state of a time-varying stimulus and memorize accumulated evidence over periods much longer than the time constant of single neurons. Importantly, we propose that population responses and persistent working memory states represent entire probability distributions and not only single stimulus values. These memories are reflected by sustained, asynchronous patterns of activity which make relevant information available to downstream neurons within their short time window of integration. Model neurons act as predictive encoders, only firing spikes which account for new information that has not yet been signaled. Thus, spike times signal deterministically a prediction error, contrary to rate codes in which spike times are considered to be random samples of an underlying firing rate. As a consequence of this coding scheme, a multitude of spike patterns can reliably encode the same information. This results in weakly correlated, Poisson-like spike trains that are sensitive to initial conditions but robust to even high levels of external neural noise. This spike train variability reproduces the one observed in cortical sensory spike trains, but cannot be equated to noise. On the contrary, it is a consequence of optimal spike-based inference. In contrast, we show that rate-based models perform poorly when implemented with stochastically spiking neurons.

  19. Physics-based Probabilistic Seismic Hazard Analysis for Seismicity Induced by Fluid Injection

    Science.gov (United States)

    Foxall, W.; Hutchings, L. J.; Johnson, S.; Savy, J. B.

    2011-12-01

    Risk associated with induced seismicity (IS) is a significant factor in the design, permitting and operation of enhanced geothermal, geological CO2 sequestration and other fluid injection projects. Whereas conventional probabilistic seismic hazard and risk analysis (PSHA, PSRA) methods provide an overall framework, they require adaptation to address specific characteristics of induced earthquake occurrence and ground motion estimation, and the nature of the resulting risk. The first problem is to predict the earthquake frequency-magnitude distribution of induced events for PSHA required at the design and permitting stage before the start of injection, when an appropriate earthquake catalog clearly does not exist. Furthermore, observations and theory show that the occurrence of earthquakes induced by an evolving pore-pressure field is time-dependent, and hence does not conform to the assumption of Poissonian behavior in conventional PSHA. We present an approach to this problem based on generation of an induced seismicity catalog using numerical simulation of pressure-induced shear failure in a model of the geologic structure and stress regime in and surrounding the reservoir. The model is based on available measurements of site-specific in-situ properties as well as generic earthquake source parameters. We also discuss semi-empirical analysis to sequentially update hazard and risk estimates for input to management and mitigation strategies using earthquake data recorded during and after injection. The second important difference from conventional PSRA is that in addition to potentially damaging ground motions a significant risk associated with induce seismicity in general is the perceived nuisance caused in nearby communities by small, local felt earthquakes, which in general occur relatively frequently. Including these small, usually shallow earthquakes in the hazard analysis requires extending the ground motion frequency band considered to include the high

  20. An energy-based approach to estimate seismic attenuation due to wave-induced fluid flow in heterogeneous poroelastic media

    Science.gov (United States)

    Solazzi, Santiago G.; Rubino, J. Germán; Müller, Tobias M.; Milani, Marco; Guarracino, Luis; Holliger, Klaus

    2016-11-01

    Wave-induced fluid flow (WIFF) due to the presence of mesoscopic heterogeneities is considered as one of the main seismic attenuation mechanisms in the shallower parts of the Earth's crust. For this reason, several models have been developed to quantify seismic attenuation in the presence of heterogeneities of varying complexity, ranging from periodically layered media to rocks containing fractures and highly irregular distributions of fluid patches. Most of these models are based on Biot's theory of poroelasticity and make use of the assumption that the upscaled counterpart of a heterogeneous poroelastic medium can be represented by a homogeneous viscoelastic solid. Under this dynamic-equivalent viscoelastic medium (DEVM) assumption, attenuation is quantified in terms of the ratio of the imaginary and real parts of a frequency-dependent, complex-valued viscoelastic modulus. Laboratory measurements on fluid-saturated rock samples also rely on this DEVM assumption when inferring attenuation from the phase shift between the applied stress and the resulting strain. However, whether it is correct to use an effective viscoelastic medium to represent the attenuation arising from WIFF at mesoscopic scales in heterogeneous poroelastic media remains largely unexplored. In this work, we present an alternative approach to estimate seismic attenuation due to WIFF. It is fully rooted in the framework of poroelasticity and is based on the quantification of the dissipated power and stored strain energy resulting from numerical oscillatory relaxation tests. We employ this methodology to compare different definitions of the inverse quality factor for a set of pertinent scenarios, including patchy saturation and fractured rocks. This numerical analysis allows us to verify the correctness of the DEVM assumption in the presence of different kinds of heterogeneities. The proposed methodology has the key advantage of providing the local contributions of energy dissipation to the overall

  1. 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

    2017-02-17

    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.

  2. Some vegetable oil with your rock chips? Alternative to diesel-based drilling fluids means cheaper cuttings disposal

    Energy Technology Data Exchange (ETDEWEB)

    Roche, P.

    2009-07-15

    Oil-based drilling fluids have generally provided more advantages over water-based muds but at a higher cost, including the cost of disposing massive amounts of oil-stained cuttings. There are also health and safety considerations associated with diesel-based drilling fluids. Water-based drilling muds can be mixed with other materials and buried on the lease site. Louisiana-based Rapid Energy Services has developed a drilling fluid that uses water and vegetable oil instead of hydrocarbons. The fluid is reusable and the cuttings do not require special disposal sites. The product known as Quantum EF is also targeting potassium silicate drilling fluids. Rapid Energy Services licensed the Canadian rights to the technology to Calgary-based Mud Master Drilling Fluid Services Ltd. The new drilling fluid was first tested in a field trial in northwestern Alberta by Calgary-based Amarone Oil and Gas Ltd. The product provided good shale inhibition while drilling as well as good hole cleaning. The greatest advantage is the Quantum product does not require chloride for inhibition and can be disposed of through land spreading or mixing and burying. Quantum EF is a water-external phase, notably 85 per cent water and 15 per cent oil from seeds such as canola. A water-external phase does not produce oil-wet cuttings. The drilling fluid has low levels of potassium and the additives are considered to be bio-nutrients. In the event of a spill, the soil will be fully naturally remediated within 28 days. Precautions must be taken during winter drilling to ensure the fluid does not freeze. 1 ref.

  3. Academic Success in Context-Based Chemistry: Demonstrating fluid transitions between concepts and context

    Science.gov (United States)

    King, Donna Therese; Ritchie, Stephen M.

    2013-05-01

    Curriculum developers and researchers have promoted context-based programmes to arrest waning student interest and participation in the enabling sciences at high school and university. Context-based programmes aim for student connections between scientific discourse and real-world contexts to elevate curricular relevance without diminishing conceptual understanding. This interpretive study explored the learning transactions in one 11th grade context-based chemistry classroom where the context was the local creek. The dialectic of agency/structure was used as a lens to examine how the practices in classroom interactions afforded students the agency for learning. The results suggest that first, fluid transitions were evident in the student-student interactions involving successful students; and second, fluid transitions linking concepts to context were evident in the students' successful reports. The study reveals that the structures of writing and collaborating in groups enabled students' agential and fluent movement between the field of the real-world creek and the field of the formal chemistry classroom. Furthermore, characteristics of academically successful students in context-based chemistry are highlighted. Research, teaching, and future directions for context-based science teaching are discussed.

  4. Kinetics of anaerobic degradation of glycol-based type I aircraft deicing fluids.

    Science.gov (United States)

    Schoenberg, T; Veltman, S; Switzenbaum, M

    2001-01-01

    The kinetics of anaerobic degradation of glycol-based Type I aircraft deicing fluids (ADFs) were characterized using suspended-growth fill-and-draw reactors. Both Type I ADFs tested showed near-complete anaerobic degradability. First-order degradation rate constants of 3.5 d(-1) for the propylene glycol-based Type I ADF and 5.2 d(-1) for the ethylene glycol-based Type I ADF were obtained through continuous-culture means under mesophilic conditions (35 degrees C). Fill-and-draw operation at lower temperatures affected anaerobic degradability only minimally down to 25 degrees C but substantially below 25 degrees C. High Type I ADF feed concentrations substantially affected degradability. Batch testing of fill-and-draw reactors resulted in first-order degradation rate constants of 1.9 d(-1) for propylene glycol-based Type I ADF and 3.5 d(-1) for ethylene glycol-based Type I ADF.

  5. Quality of Work and Team- and Project Based Work Practices in Engineering

    DEFF Research Database (Denmark)

    Buch, Anders; Andersen, Vibeke

    2015-01-01

    It is the aim of this paper to investigate teamwork amongst professionals in engineering consultancy companies in order to discern how teamwork affects the collaboration and work practices of the professionals and eventually their quality of work. The paper investigates how professional engineering...... ractices are enacted in two engineering consultancy companies in Denmark where ‘teamwork’ has been or is an ideal for organizing work....

  6. Facilitated Work Based Learning - analyseret i et pragmatisk perspektiv

    DEFF Research Database (Denmark)

    Thomassen, Anja Overgaard

    Ph.d.-afhandlingen behandler, med afsæt i John Deweys (1859-1952) pragmatisme, Facilitated Work Based Learning (FWBL) der er en tilgang til efter/videreuddannelse. På baggrund af konkrete uddannelsesforløb gennemført ud fra FWBL analyseres de udfordringer der opstår omkring gennemførelse af...... mødes for at samarbejde. Afhandlingen bidrager med et nyt begreb kaldet "den tredje kontekst" der tydeliggør, hvordan uddannelse, der gennemføres i en virksomhed, kan forstås. Ligeledes udvikles der, med afsæt i Deweys pragmatisme, en model der tydeliggør, hvorledes kompetenceudvikling kan understøttes...

  7. Plastic variational principle based on the least work consumption principle

    Institute of Scientific and Technical Information of China (English)

    唐松花; 罗迎社; 周筑宝; 王智超

    2008-01-01

    Plastic variational principles are foundation to solve the boundary-value problems of plastic mechanics with the variational method(or energy method) and finite element method.The most convenient way of establishing different kinds of variational principles is to set up the extreme principle related to the studied problem.Based on a general new extreme principle-the Least work consumption principle,the variational principles of the rigid-plastic and rigid-viscoplastic material were derived.In comparison with existing methods,the method in this paper is more clear and direct,and the physical meaning is clear-cut.This method can offer a new way for establishing other kinds of variational principles.

  8. [Computer work and De Quervain's tenosynovitis: an evidence based approach].

    Science.gov (United States)

    Gigante, M R; Martinotti, I; Cirla, P E

    2012-01-01

    The debate around the role of the work at personal computer as cause of De Quervain's Tenosynovitis was developed partially, without considering multidisciplinary available data. A systematic review of the literature, using an evidence-based approach, was performed. In disorders associated with the use of VDU, we must distinguish those at the upper limbs and among them those related to an overload. Experimental studies on the occurrence of De Quervain's Tenosynovitis are quite limited, as well as clinically are quite difficult to prove the professional etiology, considering the interference due to other activities of daily living or to the biological susceptibility (i.e. anatomical variability, sex, age, exercise). At present there is no evidence of any connection between De Quervain syndrome and time of use of the personal computer or keyboard, limited evidence of correlation is found with time using a mouse. No data are available regarding the use exclusively or predominantly for personal laptops or mobile "smart phone".

  9. A Longitudinal Study of Higher-Order Thinking Skills: Working Memory and Fluid Reasoning in Childhood Enhance Complex Problem Solving in Adolescence

    Directory of Open Access Journals (Sweden)

    Samuel eGreiff

    2015-07-01

    Full Text Available Scientists have studied the development of the human mind for decades and have accumulated an impressive number of empirical studies that have provided ample support for the notion that early cognitive performance during infancy and childhood is an important predictor of later cognitive performance during adulthood. As children move from childhood into adolescence, their mental development increasingly involves higher-order cognitive skills that are crucial for successful planning, decision-making, and problem solving. Importantly, few studies have employed higher-order thinking skills such as Complex Problem Solving (CPS as developmental outcomes in adolescents. To fill this gap, we tested a longitudinal developmental model in a sample of 2,021 Finnish sixth grade students (M = 12.41 years, SD = 0.52; 1,041 female, 978 male, 2 missing sex. We assessed working memory and fluid reasoning at age 12 as predictors of two CPS dimensions: knowledge acquisition and knowledge application. We further assessed students’ CPS performance 3 years later as a developmental outcome (N= 1696; M = 15.22 years, SD = 0.43; 867 female, 829 male. Missing data partly occurred due to dropout and technical problems during the first days of testing and varied across indicators and time with a mean of 27.2%. Results revealed that fluid reasoning was a strong predictor of both CPS dimensions, whereas working memory exhibited only a small influence on one of the two CPS dimensions. These results provide strong support for the view that CPS involves fluid reasoning and, to a lesser extent, working memory in childhood, and from there evolves into an increasingly complex structure of higher-order cognitive skills in adolescence.

  10. Parametric and working fluid analysis of a combined organic Rankine-vapor compression refrigeration system activated by low-grade thermal energy

    Directory of Open Access Journals (Sweden)

    B. Saleh

    2016-09-01

    Full Text Available The potential use of many common hydrofluorocarbons and hydrocarbons as well as new hydrofluoroolefins, i.e. R1234yf and R1234ze(E working fluids for a combined organic Rankine cycle and vapor compression refrigeration (ORC-VCR system activated by low-grade thermal energy is evaluated. The basic ORC operates between 80 and 40 °C typical for low-grade thermal energy power plants while the basic VCR cycle operates between 5 and 40 °C. The system performance is characterized by the overall system coefficient of performance (COPS and the total mass flow rate of the working fluid for each kW cooling capacity (ṁtotal. The effects of different working parameters such as the evaporator, condenser, and boiler temperatures on the system performance are examined. The results illustrate that the maximum COPS values are attained using the highest boiling candidates with overhanging T-s diagram, i.e. R245fa and R600, while R600 has the lowest ṁtotal under the considered operating conditions. Among the proposed candidates, R600 is the best candidate for the ORC-VCR system from the perspectives of environmental issues and system performance. Nevertheless, its flammability should attract enough attention. The maximum COPS using R600 is found to reach up to 0.718 at a condenser temperature of 30 °C and the basic values for the remaining parameters.

  11. Maximum power output of a class of irreversible non-regeneration heat engines with a non-uniform working fluid and linear phenomenological heat transfer law

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Maximum power output of a class of irreversible non-regeneration heat engines with non-uniform working fluid,in which heat transfers between the working fluid and the heat reservoirs obey the linear phenomenological heat transfer law [q ∝Δ(T-1)],are studied in this paper. Optimal control theory is used to determine the upper bounds of power of the heat engine for the lumped-parameter model and the distributed-parameter model,respectively. The results show that the maximum power output of the heat engine in the distributed-parameter model is less than or equal to that in the lumped-parameter model,which could provide more realistic guidelines for real heat engines. Analytical solutions of the maximum power output are obtained for the irreversible heat engines working between constant temperature reservoirs. For the irreversible heat engine operating between variable temperature reservoirs,a numerical example for the lumped-parameter model is provided by numerical calculation. The effects of changes of reservoir’s temperature on the maximum power of the heat engine are analyzed. The obtained results are,in addition,compared with those obtained with Newtonian heat transfer law [q ∝Δ(T)].

  12. Parametric and working fluid analysis of a combined organic Rankine-vapor compression refrigeration system activated by low-grade thermal energy.

    Science.gov (United States)

    Saleh, B

    2016-09-01

    The potential use of many common hydrofluorocarbons and hydrocarbons as well as new hydrofluoroolefins, i.e. R1234yf and R1234ze(E) working fluids for a combined organic Rankine cycle and vapor compression refrigeration (ORC-VCR) system activated by low-grade thermal energy is evaluated. The basic ORC operates between 80 and 40 °C typical for low-grade thermal energy power plants while the basic VCR cycle operates between 5 and 40 °C. The system performance is characterized by the overall system coefficient of performance (COPS) and the total mass flow rate of the working fluid for each kW cooling capacity ([Formula: see text]). The effects of different working parameters such as the evaporator, condenser, and boiler temperatures on the system performance are examined. The results illustrate that the maximum COPS values are attained using the highest boiling candidates with overhanging T-s diagram, i.e. R245fa and R600, while R600 has the lowest [Formula: see text] under the considered operating conditions. Among the proposed candidates, R600 is the best candidate for the ORC-VCR system from the perspectives of environmental issues and system performance. Nevertheless, its flammability should attract enough attention. The maximum COPS using R600 is found to reach up to 0.718 at a condenser temperature of 30 °C and the basic values for the remaining parameters.

  13. Research on Working Process Characteristic of Claw Type Fluid Machinery%爪式流体机械工作过程特性研究

    Institute of Scientific and Technical Information of China (English)

    王君; 刘凯; 姜希彤; 由兆举

    2012-01-01

    A special working process of claw type fluid machinery suction was defined as mixture process, and its working processes, including suction, compression, discharge and mixed process, were analyzed. The changing relation of volume, pressure and temperature varied with shaft rotation angle were investigated, and the rule of resistance moment of claw type rotor in working process was obtained. The study content will help to improve the design and the performance of the claw type fluid machinery.%将爪式流体机械所特有的一个工作过程定义为混合过程,分析了爪式流体机械工作全过程包括吸气、压缩、排气和混合过程的工作特性,讨论了工作过程中容积、压力和温度等状态参数随主轴转角间的变化关系;并得到了爪式转子在工作过程中的所受的阻力矩的变化规律.研究内容有助于爪式转子的型线设计和性能提高.

  14. von Kármán–Howarth and Corrsin equations closure based on Lagrangian description of the fluid motion

    Energy Technology Data Exchange (ETDEWEB)

    Divitiis, Nicola de, E-mail: n.dedivitiis@gmail.com

    2016-05-15

    A new approach to obtain the closure formulas for the von Kármán–Howarth and Corrsin equations is presented, which is based on the Lagrangian representation of the fluid motion, and on the Liouville theorem associated to the kinematics of a pair of fluid particles. This kinematics is characterized by the finite scale separation vector which is assumed to be statistically independent from the velocity field. Such assumption is justified by the hypothesis of fully developed turbulence and by the property that this vector varies much more rapidly than the velocity field. This formulation leads to the closure formulas of von Kármán–Howarth and Corrsin equations in terms of longitudinal velocity and temperature correlations following a demonstration completely different with respect to the previous works. Some of the properties and the limitations of the closed equations are discussed. In particular, we show that the times of evolution of the developed kinetic energy and temperature spectra are finite quantities which depend on the initial conditions.

  15. 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.

  16. 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.

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

    Directory of Open Access Journals (Sweden)

    Annamaria eDi Fabio

    2015-04-01

    Full Text Available 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 emotional intelligence to social support, beyond the effects of fluid intelligence and personality traits. The Advanced Progressive Matrices (APM, the Big Five Questionnaire (BFQ, the Mayer Salovey Caruso Emotional Intelligence test (MSCEIT, and the Multidimensional scale of Perceived Social Support (MSPSS 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 emotional intelligence in relation to perceived social support. Since ability based emotional intelligence can be increased through specific training, the results of the present study highlight new possibilities for research and intervention in a preventive framework.

  18. Problem based Learning versus Design Thinking in Team based Project work

    DEFF Research Database (Denmark)

    Denise J. Stokholm, Marianne

    2014-01-01

    based project work. The paper will exemplify how projects work is organized, supervised, staged and reported. It will investigate the practical organization of the teamwork and process as well as the dominating mindsets and methods used during the process. Comparing the two models concerning...

  19. An SV-GMR Needle Sensor-Based Estimation of Volume Density of Magnetic Fluid inside Human Body

    Directory of Open Access Journals (Sweden)

    C. P. Gooneratne

    2008-01-01

    Full Text Available A spin-valve giant magneto-resistive (SV-GMR sensor of needle-type configuration is reported to estimate the volume density of magnetic fluid inside human body. The magnetic fluid is usually injected into human body to kill cancerous cell using hyperthermia-based treatment. To control the heat treatment, a good knowledge of temperature is very much essential. The SV-GMR-based needle-type sensor is used to measure the magnetic flux density of the magnetic fluid inside the human body from which the temperature is estimated. The needle-type sensor provides a semi-invasive approach of temperature determination.

  20. Evidence-based practice in group work with incarcerated youth.

    Science.gov (United States)

    Quinn, Ashley; Shera, Wes

    2009-01-01

    As a result of the Youth Criminal Justice Act's increased focus on restorative justice, treatment, rehabilitation, and reintegration of youth, many more juvenile offenders require mental health services while resident in youth detention facilities [Youth Criminal Justice Act (2002, c.1). Ottawa: Department of Justice Canada. Retrieved September 19, 2008 from http://laws.justice.gc.ca/en/Y-1.5]. Several common characteristics such as violence, aggression, and other antisocial behaviors, associated with criminal behavior, have been identified among male and female offenders. Dialectical behavior therapy, originally developed by Linehan [Linehan, M. M., 1993a. Cognitive-behavioural treatment of borderline personality disorder. New York: Guildford Press] for chronically parasuicidal women diagnosed with borderline personality disorder, has been successfully modified for use with other populations, including violent and impulse-oriented male and female adolescents residing in correctional facilities. The intent of this article is to encourage the wider use of dialectical behavior therapy (DBT) with young offenders. It includes an extensive review of the evidence-base to date and describes some of the creative modifications that have been made to standard DBT program format to meet the particular needs of various groups in both Canada and the United States. In keeping with the movement toward more evidence-based practice, the authors argue that DBT is a promising approach in group work with incarcerated adolescents and should be more widely used.

  1. Study of Nano Particles for Enhanced Heat Transfer Characteristics of Base Fluids for Cool Thermal Energy System

    Directory of Open Access Journals (Sweden)

    Promit Choudhury

    2014-04-01

    Full Text Available Reliable heat transfer is very crucial for heat demand and supply related applications where the optimum demand is not met. Cool thermal energy systems are the units which find application in conditioning and preserving items. A colloidal mixture of nano particles in a base fluid tremendously enhances the heat transfer characteristics of the original base fluid and is ideally suited for practical application due to its marvelous characteristics.

  2. 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.

  3. Fluid-structure interaction-based biomechanical perception model for tactile sensing.

    Science.gov (United States)

    Wang, Zheng

    2013-01-01

    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.

  4. All-fiber magnetic-field sensor based on microfiber knot resonator and magnetic fluid.

    Science.gov (United States)

    Li, Xianli; Ding, Hui

    2012-12-15

    All-fiber magnetic-field sensor based on a device consisting of a microfiber knot resonator and magnetic fluid is proposed for the first time in this Letter. Sensor principles and package technology are introduced in detail. Experimental results show that the resonance wavelength of the proposed sensor regularly varies with changes to the applied magnetic field. When the magnetic field is increased to 600 Oe, the wavelength shift reaches nearly 100 pm. Moreover, the sensor responding to the 50 Hz alternating magnetic field is also experimentally investigated, and a minimal detectable magnetic-field strength of 10 Oe is successfully achieved.

  5. Enantioseparation of methamphetamine by supercritical fluid chromatography with cellulose-based packed column.

    Science.gov (United States)

    Segawa, Hiroki; Iwata, Yuko T; Yamamuro, Tadashi; Kuwayama, Kenji; Tsujikawa, Kenji; Kanamori, Tatsuyuki; Inoue, Hiroyuki

    2017-02-04

    The enantiomers of methamphetamine were differentiated by supercritical fluid chromatography (SFC) with an enantioselective cellulose-based packed column. The optimization of the chromatographic conditions was achieved by changing column temperature, co-solvent proportion, additive concentration, flow rate and back pressure. In particular, the additive concentration crucially changed the resolution between the enantiomers. After determining the optimized conditions, the enantiomers of methamphetamine were successfully separated. The analytical precision, accuracy and limit of detection were checked by using the authentic standard and seized real samples. We believe that chiral SFC is a promising method for enantioseparation of forensic samples.

  6. 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.

  7. Performance Comparison and Selection of Transformer Fluid

    OpenAIRE

    Lu Yang; Liu Shi Jia

    2016-01-01

    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 compr...

  8. Idiopathic cerebrospinal fluid overproduction: case-based review of the pathophysiological mechanism implied in the cerebrospinal fluid production.

    Science.gov (United States)

    Trevisi, Gianluca; Frassanito, Paolo; Di Rocco, Concezio

    2014-08-28

    Cerebrospinal fluid (CSF) overproduction results from either CSF infection or choroid plexus hypertrophy or tumor, with only a single idiopathic case described so far. We report a unique case of a male infant with Crouzon syndrome who presented with intracranial hypertension, caused by up to 4-fold increase in CSF daily production. Conditions related to CSF overproduction, namely central nervous system infections and choroid plexus hypertrophy or tumor, were ruled out by repeated magnetic resonance imaging and CSF samples. Medical therapy failed to reduce CSF production and the patient underwent several shunting procedures, cranial expansion, and endoscopic coagulation of the choroid plexus. This article thoroughly reviews pertinent literature on CSF production mechanisms and possible therapeutic implications.

  9. Computational fluid dynamics based bulbous bow optimization using a genetic algorithm

    Science.gov (United States)

    Mahmood, Shahid; Huang, Debo

    2012-09-01

    Computational fluid dynamics (CFD) plays a major role in predicting the flow behavior of a ship. With the development of fast computers and robust CFD software, CFD has become an important tool for designers and engineers in the ship industry. In this paper, the hull form of a ship was optimized for total resistance using CFD as a calculation tool and a genetic algorithm as an optimization tool. CFD based optimization consists of major steps involving automatic generation of geometry based on design parameters, automatic generation of mesh, automatic analysis of fluid flow to calculate the required objective/cost function, and finally an optimization tool to evaluate the cost for optimization. In this paper, integration of a genetic algorithm program, written in MATLAB, was carried out with the geometry and meshing software GAMBIT and CFD analysis software FLUENT. Different geometries of additive bulbous bow were incorporated in the original hull based on design parameters. These design variables were optimized to achieve a minimum cost function of "total resistance". Integration of a genetic algorithm with CFD tools proves to be effective for hull form optimization.

  10. Magnetorheological fluid based on submicrometric silica-coated magnetite particles under an oscillatory magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Agustín-Serrano, R. [Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Puebla, Puebla 72570, México (Mexico); Donado, F., E-mail: fernando@uaeh.edu.mx [Instituto de Ciencias Básicas e Ingeniería de la Universidad Autónoma del Estado de Hidalgo-AAMF, Pachuca 42184, México (Mexico); Rubio-Rosas, E. [Centro Universitario de Vinculación, Universidad Autónoma de Puebla, Puebla 72570, México (Mexico)

    2013-06-15

    An experimental study conducted on the rheological properties of a magnetorheological fluid based on submicrometric silica-coated magnetite particles dispersed in silicone oil is presented. We investigated the rheological behaviour when the system is simultaneously exposed to a static field and a sinusoidal field used as a perturbation. The results show that the perturbation modifies the rheological behaviour of the system and can be used to control its physical properties; however, the changes that are induced are smaller than expected from previous results for the aggregation of particles under magnetic perturbations. We discussed this difference in terms of the ratio between the magnetic energy and the thermal energy. We observed that a threshold magnetic field exists; below it, the yield stress is practically zero, whereas above it, the yield stress grows quickly. We discuss this result in terms of a model based on chain length distribution. - Highlights: ► We study a magnetorheological fluid under an oscillatory magnetic field. ► The exponential chain length distribution depends on the average chain length. ► A simple yield stress model based on the chain length distribution is proposed.

  11. Computational Fluid Dynamics Based Bulbous Bow Optimization Using a Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    Shahid Mahmood; Debo Huang

    2012-01-01

    Computational fluid dynamics (CFD) plays a major role in predicting the flow behavior of a ship.With the development of fast computers and robust CFD software,CFD has become an important tool for designers and engineers in the ship industry.In this paper,the hull form of a ship was optimized for total resistance using CFD as a calculation tool and a genetic algorithm as an optimization tool.CFD based optimization consists of major steps involving automatic generation of geometry based on design parameters,automatic generation of mesh,automatic analysis of fluid flow to calculate the required objective/cost function,and finally an optimization tool to evaluate the cost for optimization.In this paper,integration of a genetic algorithm program,written in MATLAB,was carried out with the geometry and meshing software GAMBIT and CFD analysis software FLUENT.Different geometries of additive bulbous bow were incorporated in the original hull based on design parameters.These design variables were optimized to achieve a minimum cost function of “total resistance”.Integration of a genetic algorithm with CFD tools proves to be effective for hull form optimization.

  12. An OWAS-based analysis of nurses' working postures.

    Science.gov (United States)

    Engels, J A; Landeweerd, J A; Kant, Y

    1994-05-01

    The working postures of Dutch nurses (n = 18) in an orthopaedic ward and a urology ward were observed using the Ovako Working posture Analysis System (OWAS). During observation, both working postures and activities were recorded. A specially developed computer program was used for data analysis. By means of this program, it was possible to calculate the working posture load for each activity and the contribution of a specific activity to the total working posture load. This study shows that some activities of the nurses in both wards were performed with poor working postures. In the orthopaedic (resp. urology) ward two (resp. one) out of 19 observed postures of parts of the body were classified as Action Category 2. Moreover, 20% (resp. 16%) of the so-called typical working postures was classified in Action Category 2. This suggests, that in both wards working postures that are slightly harmful to the musculoskeletal system, occur during a substantial part of the working day. Differences between both wards with respect to working posture load and time expenditure were determined. Activities causing the workload to fall into OWAS higher Action Categories were identified. The data show that poor working postures in the nursing profession not only occur during patient handling activities but also during tasks like 'administration'. Focusing on patient-handling (i.e., lifting patients) in order to determine the load on the musculoskeletal system would therefore lead to an underestimation of the total working posture load of nurses.

  13. Heat, work and subtle fluids: a commentary on Joule (1850) ‘On the mechanical equivalent of heat’

    Science.gov (United States)

    Young, John

    2015-01-01

    James Joule played the major role in establishing the conservation of energy, or the first law of thermodynamics, as a universal, all-pervasive principle of physics. He was an experimentalist par excellence and his place in the development of thermodynamics is unarguable. This article discusses Joule's life and scientific work culminating in the 1850 paper, where he presented his detailed measurements of the mechanical equivalent of heat using his famous paddle-wheel apparatus. Joule's long series of experiments in the 1840s leading to his realisation that the conservation of energy was probably of universal validity is discussed in context with the work of other pioneers, notably Sadi Carnot, who effectively formulated the principle of the second law of thermodynamics a quarter of a century before the first law was accepted. The story of Joule's work is a story of an uphill struggle against a critical scientific establishment unwilling to accept the mounting evidence until it was impossible to ignore. His difficulties in attracting funding and publishing in reputable journals despite the quality of his work will resonate with many young scientists and engineers of the present day. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society. PMID:25750152

  14. Rule-Based Multidisciplinary Tool for Unsteady Reacting Real-Fluid Flows Project

    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...

  15. Reflexive Professionalism as a Second Generation of Evidence-Based Practice: Some Considerations on the Special Issue "What Works? Modernizing the Knowledge-Base of Social Work"

    Science.gov (United States)

    Otto, Hans-Uwe; Polutta, Andreas; Ziegler, Holger

    2009-01-01

    This article refers sympathetically to the thoughtful debates and positions in the "Research on Social Work Practice" ("RSWP"; Special Issue, July, 2008 issue) on "What Works? Modernizing the Knowledge-Base of Social Work." It highlights the need for empirical efficacy and effectiveness research in social work and appreciates empirical rigor…

  16. Mixing and turbulent mixing in fluids, plasma and materials: summary of works presented at the 3rd International Conference on Turbulent Mixing and Beyond

    Science.gov (United States)

    Gauthier, Serge; Keane, Christopher J.; Niemela, Joseph J.; Abarzhi, Snezhana I.

    2013-07-01

    was held in the summer of 2011 at the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy. The papers are arranged by TMB themes, and within each theme they are ordered alphabetically by the last name of the first author. The collection includes regular research papers, a few research briefs and review papers. The review papers are published as 'Comments' articles in Physica Scripta . Canonical turbulence and turbulent mixing. Six papers are devoted to canonical turbulence and turbulent mixing. Baumert presents a theory of shear-generated turbulence, which is based on a two-fluid concept. Gampert et al investigate the problem of adequate representation of turbulent structures by applying a decomposition of the field of the turbulent kinetic energy into regions of compressive and extensive strain. Paul and Narashima consider the dynamics of a temporal mixing layer using a vortex sheet model. Schaefer et al analyse the joint statistics and conditional mean strain rates of streamline segments in turbulent flows. Sirota and Zybin deepen their discussion of the connection between Lagrangian and Eulerian velocity structure functions in hydrodynamic turbulence. Talbot et al investigate the heterogeneous mixing by considering gases of very nearly equal densities and very different viscosities. Wall-bounded flows. Three papers are dedicated to wall-bounded flows. Mok et al use the Bayesian spectral density approach to identify the dominant free surface fluctuation frequency downstream of an oscillating hydraulic jump. Tejada-Martinez et al employ large eddy numerical simulations to study wind-driven shallow water flows with and without full-depth Langmuir circulation (parallel counter rotating vortices). Wu et al re-evaluate the Karman constant based on a multi-layer analytical theory of Prandtl's mixing length function. Non-equilibrium processes. This theme is represented by two papers. Chasheckhin and Zagumennyi consider non-equilibrium processes

  17. 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

    2017-02-08

    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.

  18. Blood viscosity monitoring during cardiopulmonary bypass based on pressure-flow characteristics of a Newtonian fluid.

    Science.gov (United States)

    Okahara, Shigeyuki; Zu Soh; Takahashi, Shinya; Sueda, Taijiro; Tsuji, Toshio

    2016-08-01

    We proposed a blood viscosity estimation method based on pressure-flow characteristics of oxygenators used during cardiopulmonary bypass (CPB) in a previous study that showed the estimated viscosity to correlate well with the measured viscosity. However, the determination of the parameters included in the method required the use of blood, thereby leading to high cost of calibration. Therefore, in this study we propose a new method to monitor blood viscosity, which approximates the pressure-flow characteristics of blood considered as a non-Newtonian fluid with characteristics of a Newtonian fluid by using the parameters derived from glycerin solution to enable ease of acquisition. Because parameters used in the estimation method are based on fluid types, bovine blood parameters were used to calculate estimated viscosity (ηe), and glycerin parameters were used to estimate deemed viscosity (ηdeem). Three samples of whole bovine blood with different hematocrit levels (21.8%, 31.0%, and 39.8%) were prepared and perfused into the oxygenator. As the temperature changed from 37 °C to 27 °C, the oxygenator mean inlet pressure and outlet pressure were recorded for flows of 2 L/min and 4 L/min, and the viscosity was estimated. The value of deemed viscosity calculated with the glycerin parameters was lower than estimated viscosity calculated with bovine blood parameters by 20-33% at 21.8% hematocrit, 12-27% at 31.0% hematocrit, and 10-15% at 39.8% hematocrit. Furthermore, deemed viscosity was lower than estimated viscosity by 10-30% at 2 L/min and 30-40% at 4 L/min. Nevertheless, estimated and deemed viscosities varied with a similar slope. Therefore, this shows that deemed viscosity achieved using glycerin parameters may be capable of successfully monitoring relative viscosity changes of blood in a perfusing oxygenator.

  19. Study on Braking Sensation Based on Urban Working Conditions

    Directory of Open Access Journals (Sweden)

    Abi Lanie

    2017-01-01

    Full Text Available In this paper we researched the vehicle braking sense in three aspects of human, vehicle and environment and analysed their impacts on brake feeling. Through the real vehicle test we analysed the relationship among pedal force, pedal travel and deceleration. We used dynamometer test method to study the brake noise question. We designed a fixture which could imitate the suspension and made the test more close to the true level. Moreover we discussed how to establish the evaluation system of vehicle braking condition. Through real vehicle test of braking, we can test and record the brake system parameters in the braking process under urban working conditions. We recorded the brake frequency, the change of brake speed and brake disc temperature. Meanwhile, based on the analysis of braking condition, we put forward the index of brake load to reflect the city’s traffic conditions. Experiment show that the braking condition and brake feel are related, braking condition also provides theoretical support for the design of brake system.

  20. Evolutionary Prisoner's Dilemma Game Based on Division of Work

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-Hua; WANG Bing-Hong; LIU Run-Ran; YANG Han-Xin

    2009-01-01

    We propose a new two-type-player prisoner's dilemma game based on the division of work on a square lattice, in which a fraction of the population μ are assigned type A and the rest B.In a one-shot two-player game, we let both of their original payoffs be scaled by a same multiplicative factor α > 1, if two neighboring players are of different types; however we leave the payoffs unchanged if they are of the same type.Then we show that combined with the two-type setup, the square lattice can assist to induce different social ranks according to players' abilities to collect payoffs.Simulation results show that the density of cooperation is significantly promoted for a wide range of the temptation to defection parameters and that there are optimal values for both α and μ leading to the maximal cooperation level.We reach these results by analyzing the distribution of the players in the social ranks and we also show some typical snapshots of the system.

  1. Apparatus for Comparing Thermal Conductivity of Nanofluids and Base Fluid Using Simultaneously Measured Resistance Variation Signals from Two Hot Wire Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Shin Pyo [Kyonggi University, Suwon (Korea, Republic of)

    2015-01-15

    Exact comparisons of the thermal conductivities of the base fluid and a nanofluid are very important in the early stages of nanofluid development. A simple procedure of measuring the thermal conductivity of the two fluids by the transient hot wire method and numerically dividing these values is used for this purpose. However, because the experiments are not performed simultaneously and the physical properties of the measurement system are sometimes not properly known, large errors are incurred during the evaluation process. This article proposes a new apparatus for thermal conductivity comparison where the working principle is mainly based on relative measurement rather than absolute measurement. The measuring circuit and data processing steps are explained in detail; a validation test was performed using the well-known glycerine and engine oil.

  2. 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.

  3. Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory.

    Science.gov (United States)

    Fakhrabadi, Mir Masoud Seyyed; Rastgoo, Abbas; Ahmadian, Mohammad Taghi

    2013-01-01

    The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes.

  4. Social work knowledge of community-based services for older adults: an educational model for social work students.

    Science.gov (United States)

    Rowan, Noell L; Faul, Anna C; Birkenmaier, Julie; Damron-Rodriguez, JoAnn

    2011-02-01

    Social workers are often the key link between older adults, their families and community-based services. Thus, knowledge about older adults and community-based care is imperative for social work practice. Evaluation data are provided on a national multisite effort (N = 353) from 35 schools to assure graduate social work student's competency related to community services for older adults. Results suggest that the educational model as described in this article sets forth positive outcomes in the education of aging savvy social workers. Ongoing social work education is needed to meet the burgeoning needs of the geriatric population.

  5. Age-related changes in electrophysiological and neuropsychological indices of working memory, attention control, and fluid intelligence

    Directory of Open Access Journals (Sweden)

    Carrie Brumback Peltz

    2011-08-01

    Full Text Available Older adults exhibit great variability in their cognitive abilities, with some maintaining high levels of performance on executive control tasks and others showing significant deficits. Previous event-related potential (ERP work has shown that some of these performance differences are correlated with persistence of the novelty/frontal P3 in older adults elicited by task-relevant events, presumably reflecting variability in the capacity to suppress orienting to unexpected but no longer novel events. In recent ERP work in young adults, we showed that the operation-span task (OSPAN, a measure of attention control is predictive of the ability of individuals to keep track of stimulus sequencing and to maintain running mental representations of task stimuli, as indexed by the parietally-distributed P300 (or P3b. Both of these phenomena reflect aspects of frontal function (cognitive flexibility and attention control, respectively. To investigate these phenomena we sorted both younger and older adults into low- and high-working memory spans and low- and high-cognitive flexibility subgroups, and examined ERPs during an equal-probability choice reaction-time task. For both age groups (a participants with high OSPAN scores were better able to keep track of stimulus sequencing, as indicated by their smaller P3b to sequential changes; and (b participants with lower cognitive flexibility had larger P3a than their high-scoring counterparts. However, these two phenomena did not interact suggesting that they manifest dissociable control mechanisms. Further, the fact that both effects are already visible in younger adults suggests that at least some of the brain mechanisms underlying individual differences in cognitive aging may already operate early in life.

  6. Dynamical analysis of an accelerator-based fluid-fueled subcritical radioactive waste burning system

    Science.gov (United States)

    Woosley, Michael Louis, Jr.

    The recent revival of interest in accelerator-driven subcritical fluid-fueled systems is documented. Several important applications of these systems are mentioned. In particular, new applications have focused on the destruction of high-level radioactive waste. Systems can be designed to quickly destroy the actinides and long-lived fission products from light water reactor fuel, weapons plutonium, and other high-level defense wastes. The proposed development of these systems is used to motivate the need for the development of dynamic analysis methods for their nuclear kinetics. A physical description of the Los Alamos Accelerator-Based Conversion (ABC) concept is provided. This system is used as the basis for the kinetics study in this research. The current approach to the dynamic simulation of an accelerator-driven subcritical fluid-fueled system includes three elements: A discrete ordinates model is used to calculate the flux distribution for the source-driven system; A nodal convection model is used to calculate time-dependent isotope and temperature distributions which impact reactivity; A nodal importance weighting model is used to calculate the reactivity impact of temperature and isotope distributions and to feed this information back to the time-dependent nodal convection model. Specific transients which have been analyzed with the current modeling system are discussed. These transients include loss-of-flow and loss-of-cooling accidents, xenon and samarium transients, and cold-plug and overfueling events. The results of various transients have uncovered unpredictable behavior, unresolved design issues, and the need for active control. Modest initiating events can cause significant swings in system temperature and power. The circulation of the fluid fuel can lead to oscillations on the relatively short scale of the loop circulation time. The system responds quickly to reactivity changes because the large neutron source overwhelms the damping effect of delayed

  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. 不同有机工质的低温太阳能真空集热管的传热特性研究%Research on Heat Transfer of Different Organic Working Fluids in Solar Vacuum Heat Collecting Tube

    Institute of Scientific and Technical Information of China (English)

    葛永峰; 肖洪; 朱天宇; 毛宇飞

    2015-01-01

    以太阳能真空集热管为研究对象,基于其几何结构,分析其传热特性,建立了散热量和工质出口温度的计算模型,通过C++编程对比验证模型。最后,利用计算程序,分析一些有机工质的出口温度、吸热量与接收管温度、工质流量之间的关系。%Based on the geometric structure of e-vacuated solar collector tube and heat transfer charac-teristics,the calculation model of the working fluids'heat release and the outlet temperature is established. A calculation model of heat output and working fluid outlet temperature is established and verification mod-els are compared using C++ computer programming language. Furthermore, the relationships between outlet temperature,heat absorption,heat loss rate and mass flow rate are analyzed.

  9. 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.

  10. Work Based Learning in Intercultural Settings: A Model in Practice

    Science.gov (United States)

    Leeming, David Elvis; Mora, Maria Dolores Iglesias

    2016-01-01

    The Intercultural Business Communication at the University of Central Lancashire offers a taught module with a work placement that exists within a multicultural context as part of an MA in Intercultural Business Communication. As part of this process, students must work towards completing two practical assessments, a project presented in a report…

  11. Improvements in Children’s Fluid Intelligence with Working Memory Training%工作记忆训练提升幼儿流体智力表现

    Institute of Scientific and Technical Information of China (English)

    彭君; 莫雷; 黄平; 周莹; 王靖; 昂晨

    2014-01-01

    Fluid intelligence is one of the general intelligence types originally proposed by Cattell (1963), which refers to the innate ability of analytically solving novel problems and logically identifying new patterns and relationships. Increasing evidence has shown that cognitive training, especially those aiming at enhancing working memory, can significantly improve fluid intelligence. Moreover, central executive functions, especially working memory updating, were reported to positively correlate with individual intelligence. Thus, it is of great theoretical and practical significance to investigate whether working memory training can improve fluid intelligence. Recent studies have shown that, after short-term working memory training, performance in fluid intelligence tests, including running memory task and n-back paradigm, was improved both in adults and school-aged children. It is therefore suggested that the transfer of an improved working memory updating ability contributed to the reported training effects. However, there remain 2 major unsolved problems. On the one hand, although training has been reported effective for adults and school-aged children, few studies have focused on pre-school children. On the other hand, the demonstration of long-term effects was unreliable, because the reported studies either failed to examine lasting effects or lacked time for confirmation.%目前已有许多研究证据表明,工作记忆训练能提高成人、儿童的流体智力成绩,然而这种训练是否能够提高幼儿的流体智力表现,更为重要的是,如果训练确有成效,那么这种训练效果能否长期保持?为此,本研究选择了幼儿园4~5岁幼儿进行工作记忆训练任务,考察工作记忆训练对流体智力的提升及保持效应。实验中设立3个组:实验组、控制1组和控制2组。实验组采用单个空间n-back的工作记忆游戏程序进行训练,控制1组采用“水果忍者”的游戏程序

  12. Computational evaluation of intraventricular pressure gradients based on a fluid-structure approach.

    Science.gov (United States)

    Redaelli, A; Montevecchi, F M

    1996-11-01

    The dynamics of intraventricular blood flow, i.e. its rapid evolution, implies the rise of intraventricular pressure gradients (IPGs) characteristic of the inertia-driven events as experimentally observed by Pasipoularides (1987, 1990) and by Falsetti et al. (1986). The IPG time course is determined by the wall contraction which, in turn, depends on the load applied, namely the intraventricular pressure which is the sum of the aortic pressure (i.e., the systemic net response) and the IPG. Hence the IPGs account, at least in part, for the wall movement. These considerations suggest the necessity of a comprehensive analysis of the ventricular mechanics involving both ventricular wall mechanics and intraventricular fluid dynamics as each domain determines the boundary conditions of the other. This paper presents a computational approach to ventricular ejection mechanics based on a fluid-structure interaction calculation for the evaluation of the IPG time course. An axisymmetric model of the left ventricle is utilized. The intraventricular fluid is assumed to be Newtonian. The ventricle wall is thin and is composed of two sets of counter-rotating fibres which behave according to the modified version of Wong's sarcomere model proposed by Montevecchi and Pietrabissa and Pietrabissa et al. (1987, 1991). The full Navier-Stokes equations describing the fluid domain are solved using Galerkin's weighted residual approach in conjunction with finite element approximation (FIDAP). The wall displacement is solved using the multiplane quasi-Newton method proposed by Buzzi Ferraris and Tronconi (1985). The interaction procedure is performed by means of an external macro which compares the flow fields and the wall displacement and appropriately modifies the boundary conditions to reach the simultaneous and congruous convergence of the two problems. The results refer to a simulation of the ventricular ejection with a heart rate of 72 bpm. In this phase the ventricle ejects 61 cm3

  13. PRECISION CLEANING OF SEMICONDUCTOR SURFACES USING CARBON DIOXIDE-BASED FLUIDS

    Energy Technology Data Exchange (ETDEWEB)

    J. RUBIN; L. SIVILS; A. BUSNAINA

    1999-07-01

    The Los Alamos National Laboratory, on behalf of the Hewlett-Packard Company, is conducting tests of a closed-loop CO{sub 2}-based supercritical fluid process, known as Supercritical CO{sub 2} Resist Remover (SCORR). We have shown that this treatment process is effective in removing hard-baked, ion-implanted photoresists, and appears to be fully compatible with metallization systems. We are now performing experiments on production wafers to assess not only photoresist removal, but also residual surface contamination due to particulate and trace metals. Dense-phase (liquid or supercritical) CO{sub 2}, since it is non-polar, acts like an organic solvent and therefore has an inherently high volubility for organic compounds such as oils and greases. Also, dense CO{sub 2} has a low-viscosity and a low dielectric constant. Finally, CO{sub 2} in the liquid and supercritical fluid states can solubilize metal completing agents and surfactants. This combination of properties has interesting implications for the removal not only of organic films, but also trace metals and inorganic particulate. In this paper we discuss the possibility of using CO{sub 2} as a precision-cleaning solvent, with particular emphasis on semiconductor surfaces.

  14. Torsional Vibration Semiactive Control of Drivetrain Based on Magnetorheological Fluid Dual Mass Flywheel

    Directory of Open Access Journals (Sweden)

    Qing-hua Zu

    2015-01-01

    Full Text Available The damping characteristics of the traditional dual mass flywheel (DMF cannot be changed and can only meet one of the damping requirements. Given that the traditional DMF cannot avoid the resonance interval in start/stop conditions, it tends to generate high-resonance amplitude, which reduces the lifetime of a vehicle’s parts and leads to vehicle vibration and noise. The problems associated with the traditional DMF can be solved through the magnetorheological fluid dual mass flywheel (MRF-DMF, which was designed in this study with adjustable damping performance under different conditions. The MRF-DMF is designed based on the rheological behavior of the magnetorheological fluid (MRF, which can be changed by magnetic field strength. The damping torque of the MRF-DMF, which is generated by the MRF effect, is derived in detail. Thus, the cosimulation between the drivetrain model built in AMESim and the control system model developed in Simulink is conducted. The controller of MRF-DMF is developed, after which the torsional vibration control test of drivetrain is carried out. The cosimulation and test results indicate that MRF-DMF with the controller effectively isolates torque fluctuation of the engine in the driving condition and exhibits high performance in suppressing the resonance amplitude in the start/stop conditions.

  15. A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure.

    Science.gov (United States)

    Xia, Ji; Wang, Fuyin; Luo, Hong; Wang, Qi; Xiong, Shuidong

    2016-04-29

    Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP) cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG) written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas.

  16. A Magnetic Field Sensor Based on a Magnetic Fluid-Filled FP-FBG Structure

    Directory of Open Access Journals (Sweden)

    Ji Xia

    2016-04-01

    Full Text Available Based on the characteristic magnetic-controlled refractive index property, in this paper, a magnetic fluid is used as a sensitive medium to detect the magnetic field in the fiber optic Fabry-Perot (FP cavity. The temperature compensation in fiber Fabry-Perot magnetic sensor is demonstrated and achieved. The refractive index of the magnetic fluid varies with the applied magnetic field and external temperature, and a cross-sensitivity effect of the temperature and magnetic field occurs in the Fabry-Perot magnetic sensor and the accuracy of magnetic field measurements is affected by the thermal effect. In order to overcome this problem, we propose a modified sensor structure. With a fiber Bragg grating (FBG written in the insert fiber end of the Fabry-Perot cavity, the FBG acts as a temperature compensation unit for the magnetic field measurement and it provides an effective solution to the cross-sensitivity effect. The experimental results show that the sensitivity of magnetic field detection improves from 0.23 nm/mT to 0.53 nm/mT, and the magnetic field measurement resolution finally reaches 37.7 T. The temperature-compensated FP-FBG magnetic sensor has obvious advantages of small volume and high sensitivity, and it has a good prospect in applications in the power industry and national defense technology areas.

  17. NUMERICAL METHOD FOR MULTI-BODY FLUID INTERACTION BASED ON IMMERSED BOUNDARY METHOD

    Institute of Scientific and Technical Information of China (English)

    MING Ping-jian; ZHANG Wen-ping

    2011-01-01

    A Cartesian grid based on Immersed Boundary Method(IBM),proposed by the present authors,is extended to unstructured grids.The advantages of IBM and Body Fitted Grid(BFG)are taken to enhance the computation efficiency of the fluid structure interaction in a complex domain.There are many methods to generate the BFG,among which the unstructured grid method is the most popular.The concept of Volume Of Solid(VOS)is used to deal with the multi rigid body and fluid interaction.Each body surface is represented by a set of points which can be traced in an anti-clockwise order with the solid area on the left side of surface.An efficient Lagrange point tracking algorithm on the fixed grid is applied to search the moving boundary grid points.This method is verified by low Reynolds number flows in the range from Re =100 to 1 000 in the cavity with a moving lid.The results are in a good agreement with experimental data in literature.Finally,the flow past two moving cylinders is simulated to test the capability of the method.

  18. Choosing where to work at work - towards a theoretical model of benefits and risks of activity-based flexible offices.

    Science.gov (United States)

    Wohlers, Christina; Hertel, Guido

    2017-04-01

    Although there is a trend in today's organisations to implement activity-based flexible offices (A-FOs), only a few studies examine consequences of this new office type. Moreover, the underlying mechanisms why A-FOs might lead to different consequences as compared to cellular and open-plan offices are still unclear. This paper introduces a theoretical framework explaining benefits and risks of A-FOs based on theories from work and organisational psychology. After deriving working conditions specific for A-FOs (territoriality, autonomy, privacy, proximity and visibility), differences in working conditions between A-FOs and alternative office types are proposed. Further, we suggest how these differences in working conditions might affect work-related consequences such as well-being, satisfaction, motivation and performance on the individual, the team and the organisational level. Finally, we consider task-related (e.g. task variety), person-related (e.g. personality) and organisational (e.g. leadership) moderators. Based on this model, future research directions as well as practical implications are discussed. Practitioner Summary: Activity-based flexible offices (A-FOs) are popular in today's organisations. This article presents a theoretical model explaining why and when working in an A-FO evokes benefits and risks for individuals, teams and organisations. According to the model, A-FOs are beneficial when management encourages employees to use the environment appropriately and supports teams.

  19. Community-based rehabilitation: working in partnership with eye care

    Directory of Open Access Journals (Sweden)

    Joerg Weber

    2013-05-01

    Full Text Available Any response to the needs of people with visual impairment and their families will be more effective if eye care workers and CBR programme staff can work together at the community level.

  20. 78 FR 49281 - Trinity Adaptive Management Working Group; Public Meeting, Teleconference and Web-Based Meeting

    Science.gov (United States)

    2013-08-13

    ... Fish and Wildlife Service Trinity Adaptive Management Working Group; Public Meeting, Teleconference and... Trinity Adaptive Management Working Group (TAMWG). DATES: Public meeting, Teleconference, and web-based... Management Working Group (TAMWG) will hold a meeting. Background The TAMWG affords stakeholders...

  1. 78 FR 35312 - Trinity Adaptive Management Working Group; Public Meeting, Teleconference and Web-Based Meeting

    Science.gov (United States)

    2013-06-12

    ... Fish and Wildlife Service Trinity Adaptive Management Working Group; Public Meeting, Teleconference and... Trinity Adaptive Management Working Group (TAMWG). DATES: Public meeting, Teleconference, and web-based... Management Working Group (TAMWG) will hold a meeting. Background The TAMWG affords stakeholders...

  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. Assessment of smoking status based on cotinine levels in nasal lavage fluid

    Directory of Open Access Journals (Sweden)

    Cowart Beverly J

    2009-07-01

    Full Text Available Abstract Cotinine is a principal metabolite of nicotine with a substantially longer half-life, and cotinine levels in saliva, urine or serum are widely used to validate self-reported smoking status. The nasal cavity and olfactory system are directly exposed to tobacco smoke in smokers and in non-smokers who live with or work around smokers. However, despite the potential for a direct impact of tobacco smoke on the nasal epithelium and olfactory neurons, no prior studies have assessed cotinine levels in nasal mucus. We sought to determine whether cotinine levels in nasal lavage fluid (NLF would provide a reasonable estimate of smoke exposure. We assayed cotinine using a competitive immunoassay in NLF from 23 smokers, 10 non-smokers exposed to tobacco smoke (ETS and 60 non-smokers who did not report smoke exposure. NLF cotinine levels were significantly higher in smokers than in non-smokers, regardless of their exposure to ambient tobacco smoke. Cotinine levels in this small group of exposed non-smokers were not significantly different than those of non-exposed non-smokers. A cutoff of 1 ng/ml provided a sensitivity of 91% and a specificity of 99% for smoking status in this sample. Data were consistent with self-reported smoking status, and a cutoff of 1.0 ng/ml NLF cotinine may be used to classify smoking status. While saliva is the most easily obtained body fluid, NLF can be used to provide an objective and precise indication of smoking status and more directly reflects smoke exposure in the nasal and olfactory mucosa.

  4. Influence of filling ratio and working fluid thermal properties on starting up and heat transferring performance of closed loop plate oscillating heat pipe with parallel channels

    Science.gov (United States)

    Shi, Weixiu; Pan, Lisheng

    2017-02-01

    Using ethanol or acetone as the working fluid, the performance of starting up and heat transfer of closed-loop plate oscillating heat pipe with parallel channels (POHP-PC) were experimentally investigated by varying filling ratio, inclination, working fluids and heating power. The performance of the tested pulsating heat pipe was mainly evaluated by thermal resistance and wall temperature. Heating copper block and cold water bath were adopted in the experimental investigations. It was found that oscillating heat pipe with filling ratio of 50% started up earlier than that with 70% when heating input was 159.4 W, however, it has similar starting up performance with filling ratio of 50% as compared to 70% on the condition of heat input of 205.4 W. And heat pipe with filling ratio of 10% could not start up but directly transit to dry burning. A reasonable filling ratio range of 35%‒70% was needed in order to achieve better performance, and there are different optimal filling ratios with different heating inputs - the more heating input, the higher optimal filling ratio, and vice versa. However, the dry burning appeared easily with low filling ratio, especially at very low filling ratio, such as 10%. And higher filling ratio, such as 70%, resulted in higher heat transfer ( dry burning ) limit. With filling ratio of 70% and inclination of 75°, oscillating heat pipe with acetone started up with heating input of just 24W, but for ethanol, it needed to be achieved 68 W, Furthermore, the start time with acetone was similar as compared to that with ethanol. For steady operating state, the heating input with acetone was about 80 W, but it transited to dry burning state when heating input was greater than 160 W. However, for ethanol, the heating input was in vicinity of 160 W. Furthermore, thermal resistance with acetone was lower than that with ethanol at the same heating input of 120 W.

  5. Application of silver nanoparticles contained in ethanol as a working fluid in an oscillating heat pipe with a check valve (CLOHP/CV): a thermodynamic behaviour study

    Science.gov (United States)

    Bhuwakietkumjohn, N.; Parametthanuwat, T.

    2015-09-01

    This research focused on the thermal behaviour of oscillating heat pipe with a check valve (CLOHP/CV). The CLOHP/CV was made from a copper capillary tube with an internal diameter of 2.03 mm, 40 turns, and 2 check valves. The CLOHP/CV had three sections: the evaporator and adiabatic condenser of a length of 50, 100, and 150 mm. The angles of inclinations were 90°, 80°, 60°, 40°, 20° and 0° at normal operating conditions. The two working fluids were an ethanol and silver nanoparticles concentration of 0.5 wt% contained in the ethanol ( NE). The filling ratio was 50 % with respect to the total volume of the tube. The operating temperature ( T w ) was 45, 65, 85, 105, 125 and 150 °C. The results of the study showed that the heat flux increased significantly when the operating temperature increased, and the heat flux increased when the L e decreased from 150 to 50 mm. Furthermore, the thermal behaviour of CLOHP/CV showed the highest heat flux of 2,012.63 W/m2 at L e of 50, with an angle of inclination of 90° and operating temperature of 150 °C with NE. The behaviour of 0.5 wt% of silver nanoparticles contained in the ethanol produced a good contact angle. The 0.5 wt% of silver nanoparticles decreased the wet ability, thus increasing the thermal behaviour. The optimum concentration for the addition of silver nanoparticles in the working fluid was 0.5 wt%.

  6. Three-fluid hydrodynamics based event simulation for collisions at NICA and FAIR energies

    CERN Document Server

    Batyuk, P; Bleicher, M; Ivanov, Yu B; Karpenko, Iu; Merts, S; Nahrgang, M; Petersen, H; Rogachevsky, O

    2016-01-01

    We present a new event generator based on the three-fluid hydrodynamics approach for the early stage of the collision, followed by a particlization at the hydrodynamic decoupling surface to join to a microscopic transport model, UrQMD, to account for hadronic final state interactions. We present first results for nuclear collisions of the FAIR/NICA energy scan program (Au+Au collisions, $\\sqrt{s_{NN}}=4-11$ GeV). We address the directed flow of protons and pions as well as the proton rapidity distribution for two model EoS, one with a first order phase transition the other with a crossover type softening at high densities. The new simulation program has the unique feature that it can describe a hadron-to-quark matter transition which proceeds in the baryon stopping regime that is not accessible to previous simulation programs designed for higher energies.

  7. Tunable Effect of Double-Connective Dendritic Left-Handed Metamaterials Based on Electrorheological Fluids

    Institute of Scientific and Technical Information of China (English)

    GUO Ji-Quan; LUO Chun-Rong; ZHAO Xiao-Peng

    2009-01-01

    @@ We present double-connective dendritic unit pairs which exhibit the left-handed property for electromagnetic wave normal incidence. Based on the tunable characteristics of electrorheological fluids (ERF) as the electric field, we experimentally study the influence of the distance of electrodes, the number of stacked layers, and the intensity of the external electric field upon the ERF to the left-handed transmission peak of the double-connective dendritic structure. The results show that the transmission could be enhanced with the increase of distance or the number of layers. Furthermore, by changing the intensity of the electric fields, the left-handed transmission peak can be modulated actively, and the maximum shift is up to 160 MHz.

  8. ARTICLES: Shear Thickening Fluids Based on Additives with Different Concentrations and Molecular Chain Lengths

    Science.gov (United States)

    Xu, Yu-lei; Gong, Xing-long; Peng, Chao; Sun, Ying-qiang; Jiang, Wan-quan; Zhang, Zhong

    2010-06-01

    Shear thickening fluids (STFs) based on additives with different concentrations and molecular chain lengths were investigated. STF samples were prepared with silica and additive dispersed in polyethylene glycol (PEG) 400, where three types of additives with different molecular chain lengths of PEG4000, PEG6000, and PEG10000 were used. For PEG10000, different concentrations, including 0, 1%, 3%, and 5%, were selected to study the influences of additive concentrations. Rheological properties of the samples were measured with a rheometer. The results show that the shear thickening effect was significantly enhanced with the increase of the concentration and the molecular chain length of additives. The mechanism of enhancement was quantitatively explained with the formation of large particles clusters.

  9. 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.

  10. Operationalizing Evidence-Based Practice: The Development of an Institute for Evidence-Based Social Work

    Science.gov (United States)

    Regehr, Cheryl; Stern, Susan; Shlonsky, Aron

    2007-01-01

    Although evidence-based practice (EBP) has received increasing attention in social work in the past few years, there has been limited success in moving from academic discussion to engaging social workers in the process of implementing EBP in practice. This article describes the challenges, successes, and future aims in the process of developing a…

  11. 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

  12. PATH: a work sampling-based approach to ergonomic job analysis for construction and other non-repetitive work.

    Science.gov (United States)

    Buchholz, B; Paquet, V; Punnett, L; Lee, D; Moir, S

    1996-06-01

    A high prevalence and incidence of work-related musculoskeletal disorders have been reported in construction work. Unlike industrial production-line activity, construction work, as well as work in many other occupations (e.g. agriculture, mining), is non-repetitive in nature; job tasks are non-cyclic, or consist of long or irregular cycles. PATH (Posture, Activity, Tools and Handling), a work sampling-based approach, was developed to characterize the ergonomic hazards of construction and other non-repetitive work. The posture codes in the PATH method are based on the Ovako Work Posture Analysing System (OWAS), with other codes included for describing worker activity, tool use, loads handled and grasp type. For heavy highway construction, observations are stratified by construction stage and operation, using a taxonomy developed specifically for this purpose. Observers can code the physical characteristics of the job reliably after about 30 h of training. A pilot study of six construction laborers during four road construction operations suggests that laborers spend large proportions of time in nonneutral trunk postures and spend approximately 20% of their time performing manual material handling tasks. These results demonstrate how the PATH method can be used to identify specific construction operations and tasks that are ergonomically hazardous.

  13. Tribological properties and lubricating mechanism of SiO2 nanoparticles in water-based fluid

    Science.gov (United States)

    Bao, Y. Y.; Sun, J. L.; Kong, L. H.

    2017-03-01

    The tribological properties of surface modified SiO2 nanoparticles suspension in water-based lubricant have been studied. SiO2 (30 nm) nanoparticles were dispersed through surface modification with polyethylene glycol-200. Transmission electron microscope (TEM) and infrared (IR) spectroscopy show that SiO2 nanoparticles disperse well and stably in the water-based lubricant. The diameter of the nanoparticles is about 60 nm. Tribological properties of the water-based lubricant were evaluated using four-ball wear test machine and pin-on-disk tester under different loads and different concentrations of SiO2 nanoparticles. Wear surface morphology, element chemistry configuration of steel balls and steel rings were studied by means of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Results show that the tribological properties of the water-based fluid have been improved by addition of nanoparticles ranging from 0.1% to 0.3% concentrations. SiO2 nanoparticles deposited onto the wear surface during the sliding, which helped to reduce the friction coefficients and increase the anti-wear properties due to the miniature ball bearing effect and self-repairing performance of nanoparticles between the friction pairs. With the increase of test load, the friction coefficients decrease but the wear of the surface increase.

  14. Measurement of the Density of Base Fluids at Pressures 0.422 to 2.20 Gpa

    Science.gov (United States)

    Hamrock, B. J.; Jacobson, B. O.; Bergstroem, S. I.

    1985-01-01

    The influence of pressure on the density of six base fluids is experimentally studied for a range of pressures from 0.422 to 2.20 GPa. An important parameter used to describe the results is the change in relative volume with change in pressure dv sub r/dp. For pressures less than the solidification pressure (p ps) a small change in pressure results in a large change in dv sub r/ps. For pressures greater than the solidification pressure (p ps) there is no change in dv sub r/dp with changing pressure. The solidification pressures of the base fluids varies considerably, as do the slopes that the experimental data assumes for p ps. A new formula is developed that describes the effect of pressure on density in terms of four constants. These constants vary for the different base fluids tested.

  15. Dry Laboratories in Science Education : Computer-based Practical Work

    NARCIS (Netherlands)

    Kirschner, P.A.; Huisman, W.

    1998-01-01

    Practical (laboratory) work in science education has traditionally been used to allow students to rediscover already known concepts and ideas, to demonstrate concepts taught in the classroom or, in the case of inquirybased science curricula, to teach concepts. Often, these laboratory practicals do n

  16. 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...

  17. Faith-Based International Development Work: A Review

    OpenAIRE

    Dan Heist; Cnaan, Ram A

    2016-01-01

    In the wake of the Faith-Based Initiative in the USA, substantial research has resulted in an increased awareness of religious congregations and faith-based organizations as welfare service providers. The next frontier appears to be the role of religious organizations in international social and economic development, a topic that only recently started to attract academic interest. In this paper, we review available literature on the role that religious, or faith-based, organizations play in i...

  18. Inter-operator Reliability of Magnetic Resonance Image-Based Computational Fluid Dynamics Prediction of Cerebrospinal Fluid Motion in the Cervical Spine.

    Science.gov (United States)

    Martin, Bryn A; Yiallourou, Theresia I; Pahlavian, Soroush Heidari; Thyagaraj, Suraj; Bunck, Alexander C; Loth, Francis; Sheffer, Daniel B; Kröger, Jan Robert; Stergiopulos, Nikolaos

    2016-05-01

    For the first time, inter-operator dependence of MRI based computational fluid dynamics (CFD) modeling of cerebrospinal fluid (CSF) in the cervical spinal subarachnoid space (SSS) is evaluated. In vivo MRI flow measurements and anatomy MRI images were obtained at the cervico-medullary junction of a healthy subject and a Chiari I malformation patient. 3D anatomies of the SSS were reconstructed by manual segmentation by four independent operators for both cases. CFD results were compared at nine axial locations along the SSS in terms of hydrodynamic and geometric parameters. Intraclass correlation (ICC) assessed the inter-operator agreement for each parameter over the axial locations and coefficient of variance (CV) compared the percentage of variance for each parameter between the operators. Greater operator dependence was found for the patient (0.19 0.78). For the healthy subject, hydraulic diameter and Womersley number had the least variance (CV = ~2%). For the patient, peak diastolic velocity and Reynolds number had the smallest variance (CV = ~3%). These results show a high degree of inter-operator reliability for MRI-based CFD simulations of CSF flow in the cervical spine for healthy subjects and a lower degree of reliability for patients with Type I Chiari malformation.

  19. 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

  20. Carbon-supported base metal nanoparticles : Cellulose at work

    NARCIS (Netherlands)

    Hoekstra, Jacco; Versluijs-Helder, Marjan; Vlietstra, Edward J.; Geus, John W.; Jenneskens, Leonardus W.

    2015-01-01

    Pyrolysis of base metal salt loaded microcrystalline cellulose spheres gives a facile access to carbon-supported base metal nanoparticles, which have been characterized with temperature-dependent XRD, SEM, TEM, ICP-MS and elemental analysis. The role of cellulose is multifaceted: 1) it facilitates a

  1. Carbon-supported base metal nanoparticles: cellulose at work.

    Science.gov (United States)

    Hoekstra, Jacco; Versluijs-Helder, Marjan; Vlietstra, Edward J; Geus, John W; Jenneskens, Leonardus W

    2015-03-01

    Pyrolysis of base metal salt loaded microcrystalline cellulose spheres gives a facile access to carbon-supported base metal nanoparticles, which have been characterized with temperature-dependent XRD, SEM, TEM, ICP-MS and elemental analysis. The role of cellulose is multifaceted: 1) it facilitates a homogeneous impregnation of the aqueous base metal salt solutions, 2) it acts as an efficacious (carbonaceous) support material for the uniformly dispersed base metal salts, their oxides and the metal nanoparticles derived therefrom, and 3) it contributes as a reducing agent via carbothermal reduction for the conversion of the metal oxide nanoparticles into the metal nanoparticles. Finally, the base metal nanoparticles capable of forming metastable metal carbides catalytically convert the carbonaceous support into a mesoporous graphitic carbon material.

  2. 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.

  3. Visual Working Efficiency Analysis Method of Cockpit Based On ANN

    Directory of Open Access Journals (Sweden)

    Yingchun CHEN

    2012-09-01

    Full Text Available The Artificial Neural Networks method is applied on visual working efficiency of cockpit. A Self-Organizing Map (SOM network is demonstrated selecting material with near properties. Then a Back-Propagation (BP network automatically learns the relationship between input and output. After a set of training, the BP network is able to estimate material characteristics using knowledge and criteria learned before. Results indicate that trained network can give effective prediction for material.

  4. Phenol resin-based supports of inclined workings

    Energy Technology Data Exchange (ETDEWEB)

    Boldin, V.M.; Krivoshchekova, N.P.; Fedorova, G.G.

    1980-10-01

    This article evaluates experimental tubing supports produced in the Kuzbass. The tubings are formed from coal and phenol-formaldehyde resins. Benzene sulfonic acid is used as hardening agent. Coal with grains up to 10 mm is used as filling agent. Five phenol-formaldehyde resins (SFZh-3032U, SF-142, SF-40K0, SFZh-3032NV, SFZh-3032) are evaluated as the basis for support production. The results are given in a table. Experiments show that SFZh-3032 resin is superior to other resins as a means of improving strength and mechanical parameters of the coal body in which workings are driven. It is noted that until now 10 km of resin reinforced coal tubing support have been constructed. Capacity of equipment producing the supports is 2.5 km/year. Resin reinforced tubing is economical: it need not be removed, can be mined together with coal seam, it reduces hazard of wall or floor swelling, increases haulage capacity of workings used for underground haulage 3 to 4 times, and improves safety of work for miners. (In Russian)

  5. Control of electro-rheological fluid based resistive torque elements for use in active rehabilitation devices

    Science.gov (United States)

    Nikitczuk, Jason; Weinberg, Brian; Mavroidis, Constantinos

    2007-04-01

    In this paper we present control algorithms for novel electro-rheological fluid based resistive torque generation elements that will be used to drive the joint of a new type of portable and controllable active knee rehabilitation orthotic device (AKROD) for iso-inertial, isokinetic, and isometric exercising as well as gait retraining. The AKROD is composed of straps and rigid components for attachment to the leg, with a central hinge mechanism where a gear system is connected. The key features of AKROD include: a compact, lightweight design with highly tunable torque capabilities through a variable damper component, full portability with on-board power, control circuitry, and sensors (encoder and torque), and real-time capabilities for closed loop computer control for optimizing gait retraining. The variable damper component is achieved through an electro-rheological fluid (ERF) element that connects to the output of the gear system. Using the electrically controlled rheological properties of ERFs, compact brakes capable of supplying high resistive and controllable torques are developed. In this project, a prototype for the AKROD has been developed and tested. The AKROD's ERF resistive actuator was tested in laboratory experiments using a custom-made ERF testing apparatus (ETA). ETA provides a computer-controlled environment to test ERF brakes and actuators in various conditions and scenarios including emulating the interaction between human muscles involved with the knee and the AKROD's ERF actuators/brakes. The AKROD's ERF resistive actuator was tested in closed loop torque control experiments. A hybrid (non-linear, adaptive) proportional-integral (PI) torque controller was implemented to achieve this goal.

  6. Faith-Based International Development Work: A Review

    Directory of Open Access Journals (Sweden)

    Dan Heist

    2016-02-01

    Full Text Available In the wake of the Faith-Based Initiative in the USA, substantial research has resulted in an increased awareness of religious congregations and faith-based organizations as welfare service providers. The next frontier appears to be the role of religious organizations in international social and economic development, a topic that only recently started to attract academic interest. In this paper, we review available literature on the role that religious, or faith-based, organizations play in international social and economic development. We also provide results from our own study of USA international NGOs1 that are faith-based. We divide the paper into the positive contributions of faith-based international NGOs and the drawbacks of these NGOs. We find that faith-based nonprofits constitute almost 60 percent of USA-based international development organizations, and their contribution to international social development is quite considerable. We conclude with a call for further research and nuanced understanding of the role religion plays in international development.

  7. 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.

  8. Irrelevant features of a stimulus can either facilitate or disrupt performance in a working memory task: the role of fluid intelligence.

    Directory of Open Access Journals (Sweden)

    Bernardo Perfetti

    Full Text Available It has been shown that fluid intelligence (gf is fundamental to overcome interference due to information of a previously encoded item along a task-relevant domain. However, the biasing effect of task-irrelevant dimensions is still unclear as well as its relation with gf. The present study aimed at clarifying these issues. Gf was assessed in 60 healthy subjects. In a different session, the same subjects performed two versions (letter-detection and spatial of a three-back working memory task with a set of physically identical stimuli (letters presented at different locations on the screen. In the letter-detection task, volunteers were asked to match stimuli on the basis of their identity whereas, in the spatial task, they were required to match items on their locations. Cross-domain bias was manipulated by pseudorandomly inserting a match between the current and the three back items on the irrelevant domain. Our findings showed that a task-irrelevant feature of a salient stimulus can actually bias the ongoing performance. We revealed that, at trials in which the current and the three-back items matched on the irrelevant domain, group accuracy was lower (interference. On the other hand, at trials in which the two items matched on both the relevant and irrelevant domains, the group showed an enhancement of the performance (facilitation. Furthermore, we demonstrated that individual differences in fluid intelligence covaries with the ability to override cross-domain interference in that higher gf subjects showed better performance at interference trials than low gf subjects. Altogether, our findings suggest that stimulus features irrelevant to the task can affect cognitive performance along the relevant domain and that gf plays an important role in protecting relevant memory contents from the hampering effect of such a bias.

  9. Electrophysiological indices of interference resolution covary with individual fluid intelligence: investigating reactive control processes in a 3-back working memory task.

    Science.gov (United States)

    Perfetti, Bernardo; Varanese, Sara; Mancino, Elisa; Mercuri, Pasqua; Tesse, Marcello; Franciotti, Raffaella; Bonanni, Laura; Thomas, Astrid; Onofrj, Marco

    2014-06-01

    It has been proposed that the well-established relationship between working memory (WM) and fluid intelligence (gf) is mediated by executive mechanisms underlying interference control. The latter relies upon the integrity of a frontoparietal brain network, whose activity is modulated by general cognition. In regards to the chronology of this activation, only few EEG studies investigated the topic, although none of them examined the regional interaction or the effects of individual differences in gf. The current investigation sought at extending previous research by characterizing the EEG markers (temporal activation and regional coupling) of interference control and the effects of the individual variation in gf. To this end, we recorded the EEG activity of 33 participants while performing verbal and spatial versions of a 3-back WM task. In a separate session, participants were administered with a test of fluid intelligence. Interference-inducing trials were associated with an increased negativity in the frontal scalp region occurring in two separate time windows and probably reflecting two different stages of the underlying cognitive process. In addition, we found that scalp distribution of such activity differed among individuals, being the strongest activation of the left and right frontolateral sites related to high gf level. Finally, high- and low-gf participants showed different patterns in the modulation of regional connectivity (electrodes coherence in the range of 4.5-7.5Hz) according to changes in attention load among types of trials. Our findings suggest that high-gf participants may rely upon effective engagement and modulation of attention resources to face interference.

  10. Making activity-based funding work for mental health.

    Science.gov (United States)

    Rosenberg, Sebastian P; Hickie, Ian B

    2013-06-01

    The implementation of activity-based funding (ABF) in mental health from 1 July 2013 has significant risks and benefits. It is critical that the process of implementation is consistent with Australia's cherished goal of establishing a genuine and effective model of community-based mental health care. The infrastructure to support the application of ABF to mental health is currently weak and requires considerable development. States and territories are struggling to meet existing demand for largely hospital-based acute mental health care. There is a risk that valuable ABF-driven Commonwealth growth funds may be used to prop up these systems rather than drive the emergence of new models of community-based care. Some of these new models exist now and this article provides a short description. The aim is to help the Independent Hospital Pricing Authority better understand the landscape of mental health into which it now seeks to deploy ABF.

  11. Heating production fluids in a wellbore

    Science.gov (United States)

    Orrego, Yamila; Jankowski, Todd A.

    2016-07-12

    A method for heating a production fluid in a wellbore. The method can include heating, using a packer fluid, a working fluid flowing through a first medium disposed in a first section of the wellbore, where the first medium transfers heat from the packer fluid to the working fluid. The method can also include circulating the working fluid into a second section of the wellbore through a second medium, where the second medium transfers heat from the working fluid to the production fluid. The method can further include returning the working fluid to the first section of the wellbore through the first medium.

  12. Modeling and analysis of controllable output property of cantilever-beam inertial sensors based on magnetic fluid

    Institute of Scientific and Technical Information of China (English)

    Guixiong LIU; Peiqiang ZHANG; Chen XU

    2009-01-01

    Magnetic fluid is first introduced into thetraditional cantileverbeam senor. Based on the property of the cantilever-beam and the novel controllable mag-viscosity of magnetic fluid, the output of cantilever-beam sensors is under control so that the controllable output of the sensors can be realized. The mathematical model of the sensors is established and analyzed. The dynamic control function and the following educational results, which include the two curves of the displacement ratio and phase function with the different damping ratio and frequency ratio, are obtained based on the model. The result shows that it is valid to realize the controllable output of the sensors by controlling the viscosity of the magnetic fluid,and finally the expanded measurement range can be realized.

  13. A New IMS Based Inter-working Solution

    Science.gov (United States)

    Zhu, Zhongwen; Brunner, Richard

    With the evolution of third generation network, more and more multimedia services are developed and deployed. Any new service to be deployed in IMS network is required to inter-work with existing Internet communities or legacy terminal users in order to appreciate the end users, who are the main drivers for the service to succeed. The challenge for Inter-working between IMS (IP Multimedia Subsystem) and non-IMS network is “how to handle recipient’s address”. This is because each network has its own routable address schema. For instance, the address for Google Talk user is xmpp:xyz@google.com, which is un-routable in IMS network. Hereafter a new Inter-working (IW) solution between IMS and non-IMS network is proposed for multimedia services that include Instant Messaging, Chat, and File transfer, etc. It is an end-to-end solution built on IMS infrastructure. The Public Service Identity (PSI) defined in 3GPP standard (3rd Generation Partnership Project) is used to allow terminal clients to allocate this IW service. When sending the SIP (Session Initial Protocol) request out for multimedia services, the terminal includes the recipient’s address in the payload instead of the “Request-URI” header. In the network, the proposed solution provides the mapping rules between different networks in MM-IW (Multimedia IW). The detailed technical description and the corresponding use cases are present. The comparison with other alternatives is made. The benefits of the proposed solution are highlighted.

  14. 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.

  15. A web based semi automatic frame work for astrobiological researches

    Directory of Open Access Journals (Sweden)

    P.V. Arun

    2013-12-01

    Full Text Available Astrobiology addresses the possibility of extraterrestrial life and explores measures towards its recognition. Researches in this context are founded upon the premise that indicators of life encountered in space will be recognizable. However, effective recognition can be accomplished through a universal adaptation of life signatures without restricting solely to those attributes that represent local solutions to the challenges of survival. The life indicators should be modelled with reference to temporal and environmental variations specific to each planet and time. In this paper, we investigate a semi-automatic open source frame work for the accurate detection and interpretation of life signatures by facilitating public participation, in a similar way as adopted by SETI@home project. The involvement of public in identifying patterns can bring a thrust to the mission and is implemented using semi-automatic framework. Different advanced intelligent methodologies may augment the integration of this human machine analysis. Automatic and manual evaluations along with dynamic learning strategy have been adopted to provide accurate results. The system also helps to provide a deep public understanding about space agency’s works and facilitate a mass involvement in the astrobiological studies. It will surely help to motivate young eager minds to pursue a career in this field.

  16. Hierarchical calibration and validation of computational fluid dynamics models for solid sorbent-based carbon capture

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Canhai; Xu, Zhijie; Pan, Wenxiao; Sun, Xin; Storlie, Curtis; Marcy, Peter; Dietiker, Jean-François; Li, Tingwen; Spenik, James

    2016-01-01

    To quantify the predictive confidence of a solid sorbent-based carbon capture design, a hierarchical validation methodology—consisting of basic unit problems with increasing physical complexity coupled with filtered model-based geometric upscaling has been developed and implemented. This paper describes the computational fluid dynamics (CFD) multi-phase reactive flow simulations and the associated data flows among different unit problems performed within the said hierarchical validation approach. The bench-top experiments used in this calibration and validation effort were carefully designed to follow the desired simple-to-complex unit problem hierarchy, with corresponding data acquisition to support model parameters calibrations at each unit problem level. A Bayesian calibration procedure is employed and the posterior model parameter distributions obtained at one unit-problem level are used as prior distributions for the same parameters in the next-tier simulations. Overall, the results have demonstrated that the multiphase reactive flow models within MFIX can be used to capture the bed pressure, temperature, CO2 capture capacity, and kinetics with quantitative accuracy. The CFD modeling methodology and associated uncertainty quantification techniques presented herein offer a solid framework for estimating the predictive confidence in the virtual scale up of a larger carbon capture device.

  17. Design of a Sensor Based on Plastic Optical Fibre (POF) to Measure Fluid Flow and Turbidity.

    Science.gov (United States)

    Aiestaran, Pedro; Arrue, Jon; Zubia, Joseba

    2009-01-01

    Although many optical fibre applications are based on their capacity to transmit optical signals with low losses, it can also be desirable for the optical fibre to be strongly affected by a certain physical parameter in the environment. In this way, it can be used as a sensor for this parameter. There are many strong arguments for the use of POFs as sensors. In addition to being easy to handle and low cost, they demonstrate advantages common to all multimode optical fibres. These specifically include flexibility, small size, good electromagnetic compatibility behaviour, and in general, the possibility of measuring any phenomenon without physically interacting with it. In this paper, a sensor based on POF is designed and analysed with the aim of measuring the volume and turbidity of a low viscosity fluid, in this case water, as it passes through a pipe. A comparative study with a commercial sensor is provided to validate the proven flow measurement. Likewise, turbidity is measured using different colour dyes. Finally, this paper will present the most significant results and conclusions from all the tests which are carried out.

  18. Design of a Sensor Based on Plastic Optical Fibre (POF to Measure Fluid Flow and Turbidity

    Directory of Open Access Journals (Sweden)

    Joseba Zubia

    2009-05-01

    Full Text Available Although many optical fibre applications are based on their capacity to transmit optical signals with low losses, it can also be desirable for the optical fibre to be strongly affected by a certain physical parameter in the environment. In this way, it can be used as a sensor for this parameter. There are many strong arguments for the use of POFs as sensors. In addition to being easy to handle and low cost, they demonstrate advantages common to all multimode optical fibres. These specifically include flexibility, small size, good electromagnetic compatibility behaviour, and in general, the possibility of measuring any phenomenon without physically interacting with it. In this paper, a sensor based on POF is designed and analysed with the aim of measuring the volume and turbidity of a low viscosity fluid, in this case water, as it passes through a pipe. A comparative study with a commercial sensor is provided to validate the proven flow measurement. Likewise, turbidity is measured using different colour dyes. Finally, this paper will present the most significant results and conclusions from all the tests which are carried out.

  19. Peritoneal fluid culture

    Science.gov (United States)

    Culture - peritoneal fluid ... sent to the laboratory for Gram stain and culture. The sample is checked to see if bacteria ... based on more than just the peritoneal fluid culture (which may be negative even if you have ...

  20. Enhanced active swimming in viscoelastic fluids

    CERN Document Server

    Riley, Emily E

    2014-01-01

    Swimming microorganisms often self propel in fluids with complex rheology. While past theoretical work indicates that fluid viscoelasticity should hinder their locomotion, recent experiments on waving swimmers suggest a possible non-Newtonian enhancement of locomotion. We suggest a physical mechanism, based on fluid-structure interaction, leading to swimming in a viscoelastic fluid at a higher speed than in a Newtonian one. Using Taylor's two-dimensional swimming sheet model, we solve for the shape of an active swimmer as a balance between the external fluid stresses, the internal driving moments, and the passive elastic resistance. We show that this dynamic balance leads to a generic transition from hindered rigid swimming to enhanced flexible locomotion. The results are physically interpreted as due to a viscoelastic suction increasing the swimming amplitude in a non-Newtonian fluid and overcoming viscoelastic damping.

  1. Theoretical models for fluid thermodynamics based on the quasi-Gaussian entropy theory

    NARCIS (Netherlands)

    Amadei, Andrea

    1998-01-01

    Summary The theoretical modeling of fluid thermodynamics is one of the most challenging fields in physical chemistry. In fact the fluid behavior, except at very low density conditions, is still extremely difficult to be modeled from a statistical mechanical point of view, as for any realistic model

  2. 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...

  3. Miniaturized ionophore-based potentiometric sensors for the flow-injection determination of metformin in pharmaceutical formulations and biological fluids.

    Science.gov (United States)

    Khaled, Elmorsy; Kamel, Manal S; Hassan, Hassan N; Abd El-Alim, Sameh H; Aboul-Enein, Hassan Y

    2012-12-01

    Miniaturized potentiometric sensors based on β-cyclodextrins (β-CDs) are described for determination of metformin (Mf) in pharmaceutical preparations and biological fluids. Electrode matrix compositions are optimized on the basis of the nature and content of sensing ionophore, ionic sites and plasticizers. Coated wire electrodes (CWEs) modified with heptakis(2,3,6-tri-O-methyl)-β-CD, sodium tetrakis(4-fluorophenyl)borate (NaTFPB) and 2-fluorophenyl 2-nitrophenyl ether (f-NPE), work satisfactorily in the concentration range from 10(-6) to 10(-1) mol L(-1) with Nernstian compliance (55.7 ± 0.4 mV per decade activity) and a detection limit of 8 × 10(-7) mol L(-1). Incorporation of β-CD as a molecular recognition element improved the electrode sensitivity and selectivity due to encapsulation of Mf into the β-CD cavity (host-guest interaction). The developed electrodes have been successfully applied for the potentiometric determination of Mf under batch and flow injection analysis (FIA). FIA allows analysis of 90 samples per h offering the advantages of simplicity, accuracy and automation feasibility. The dissolution profile for metformin pharmaceutical samples (Cidophage®) was monitored using the proposed electrode in comparison with the official spectrophotometric methods. Characterization of the formed Mf-β-CD inclusion complexes is discussed in detail.

  4. Prospects of Supercritical Fluids in Realizing Graphene-Based Functional Materials.

    Science.gov (United States)

    Padmajan Sasikala, Suchithra; Poulin, Philippe; Aymonier, Cyril

    2016-04-13

    Supercritical-fluids science and technology predate all the approaches that are currently established for graphene production by several decades in advanced materials design. However, it has only recently been proposed as a plausible approach for graphene processing. Since then, supercritical fluids have emerged into contention as an alternative to existing technologies because of their scalability and versatility in processing graphene materials, which include composites, aerogels, and foams. Here, an overview is presented of such materials prepared through supercritical fluids from an advanced materials science standpoint, with a discussion on their fundamental properties and technological applications. The benefits of supercritical-fluid processing over conventional liquid-phase processing are presented. The benefits include not only better performances for advanced applications but also environmental issues associated with the synthesis process. Nevertheless, the limitations of supercritical-fluid processing are also stressed, along with challenges that are still faced toward the achievement of the great expectations from graphene materials.

  5. Making Digital Game-Based Learning Work: Domain Knowledge Transparency

    Science.gov (United States)

    Wang, Feihong; Burton, John K.

    2010-01-01

    During the past two decades, the popularity of computer and video games has prompted games to be a source of study for educational applications (Dickey, 2007). The most distinguishing characteristic of games is their capability to engage and motivate their players (Kiili, 2005). Educators started to explore game-based learning by testing…

  6. Activity-based computing for medical work in hospitals

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind

    2009-01-01

    . In a hospital, the challenges arising from the management of parallel activities and interruptions are amplified because multitasking is now combined with a high degree of mobility, collaboration, and urgency. The article presents the empirical and theoretical background for activity-based computing, its...

  7. Brain-Based Learning and Educational Neuroscience: Boundary Work

    Science.gov (United States)

    Edelenbosch, Rosanne; Kupper, Frank; Krabbendam, Lydia; Broerse, Jacqueline E. W.

    2015-01-01

    Much attention has been given to "bridging the gap" between neuroscience and educational practice. In order to gain better understanding of the nature of this gap and of possibilities to enable the linking process, we have taken a boundary perspective on these two fields and the brain-based learning approach, focusing on…

  8. Evidence-based laboratory medicine: is it working in practice?

    Science.gov (United States)

    Price, Christopher P

    2012-02-01

    The principles of Evidence-Based Medicine have been established for about two decades, with the need for evidence-based clinical practice now being accepted in most health systems around the world. These principles can be employed in laboratory medicine. The key steps in evidence-based practice, namely (i) formulating the question; (ii) searching for evidence; (iii) appraising evidence; (iv) applying evidence; and (v) assessing the experience are all accepted but, as yet, translation into daily clinical and laboratory practice has been slow. Furthermore, the demand for evidence-based laboratory medicine (EBLM) has been slow to develop.There are many contrasting observations about laboratory medicine, for example (i) there is too much testing vs insufficient testing; (ii) testing is expensive vs laboratories are expected to generate income; and (iii) test results have little impact on outcomes vs test results are crucial to clinical decision making. However, there is little evidence to support any of these observations. Integrating the principles of EBLM into routine practice will help to resolve some of these issues by identifying (a) where laboratory medicine fits into the care pathway; (b) where testing is appropriate; (c) the nature and quality of evidence required to demonstrate the clinical utility of a test; (d) how the test result impacts on clinical actions; (e) where changes in the care pathway will occur; and (f) where benefit/value can be achieved. These answers will help to establish the culture of EBLM in clinical and laboratory practice.

  9. A tomographic study of the skull base in primary spontaneous cerebrospinal fluid leaks

    Energy Technology Data Exchange (ETDEWEB)

    Giannetti, Alexandre Varella [Hospital das Clinicas, Service of Neurosurgery, Belo Horizonte (Brazil); Federal University of Minas Gerais, Department of Surgery, School of Medicine, Belo Horizonte (Brazil); Guimaraes, Roberto Eustaquio S. [Hospital das Clinicas, Services Otorhinolaryngology, Belo Horizonte (Brazil); Federal University of Minas Gerais, Department of Ophthalmology and Otorhinolaryngology, School of Medicine, Belo Horizonte (Brazil); Santiago, Ana Paula M.S. [Hospital das Clinicas, Services Radiology, Belo Horizonte (Brazil); Perpetuo, Francisco Otaviano L.; Machado, Marco Antonio O. [Computed Tomography Center of Minas Gerais, Belo Horizonte (Brazil)

    2012-05-15

    This study aims to evaluate the existence of anatomic abnormalities in the skull base that could contribute to the origin of primary spontaneous cerebrospinal fluid leaks (PSL). Twenty PSL patients were compared with 20 healthy individuals. The following features were measured through an analysis of computed tomography scans: the angles of the petrosal bones and skull base in both the sagittal and coronal planes; the anteroposterior and mediolateral diameters of the anterior skull base, sella, and sphenoid sinus; the depth of the olfactory fossa; the pneumatization of the sphenoid sinus; the position of the crista galli; and the state of the dorsum sellae. Body mass index (BMI) was compared. There were no differences between the two groups with respect to the angles and diameters of the anterior cranial fossa and the sphenoid sinus or the depth of the olfactory fossa. Pneumatization of the lateral recess of the sphenoid sinus was more frequent in the PSL group (55%) than in the control group (25%, p = 0.053). The dorsum sellae were eroded in 30% of the PSL patients but intact in all healthy subjects. PSL subjects showed higher sellae (1.0 versus 0.8 cm, p = 0.002). The average BMI of PSL patients was higher than that of the control group. Global alterations in the skull base of PSL patients were not found. The increase in the height of sellae and the erosion of its dorsum suggest intracranial hypertension. The higher BMI in the case group confirms the relation between obesity and PSL. (orig.)

  10. Computational fluid dynamics based aerodynamic optimization of the wind tunnel primary nozzle

    Science.gov (United States)

    Jan, Kolář; Václav, Dvořák

    2012-06-01

    The aerodynamic shape optimization of the supersonic flat nozzle is the aim of proposed paper. The nozzle discussed, is applied as a primary nozzle of the inlet part of supersonic wind tunnel. Supersonic nozzles of the measure area inlet parts need to guarantee several requirements of flow properties and quality. Mach number and minimal differences between real and required velocity and turbulence profiles at the nozzle exit are the most important parameters to meet. The aerodynamic shape optimization of the flat 2D nozzle in Computational Fluid Dynamics (CFD) is employed to reach as uniform exit velocity profile as possible, with the mean Mach number 1.4. Optimization process does not use any of standard routines of global or local optimum searching. Instead, newly formed routine, which exploits shape-based oriented sequence of nozzles, is used to research within whole discretized parametric space. The movement within optimization process is not driven by gradient or evolutionary too, instead, the Path of Minimal Shape Deformation is followed. Dynamic mesh approach is used to deform the shape and mesh from the actual nozzle to the subsequent one. Dynamic deformation of mesh allows to speed up whole converging process as an initialization of flow at the newly formed mesh is based on afore-computed shape. Shape-based similarity query in field of supersonic nozzles is discussed and applied. Evolutionary technique with genetic algorithm is used to search for minimal deformational path. As a result, the best variant from the set of solved shapes is analyzed at the base of momentum coefficient and desired Mach number at the nozzle exit.

  11. Infrared thermography based magnetic hyperthermia study in Fe3O4 based magnetic fluids

    Science.gov (United States)

    Lahiri, B. B.; Ranoo, Surojit; Philip, John

    2016-09-01

    Owing to the immense clinical benefits, magnetic hyperthermia is likely to emerge as an alternate cancer therapeutic procedure in the near future. Presently, radio frequency immune fiber optic based sensors are being used to monitor temperature changes during magnetic hyperthermia measurements, which have inherent limitations due to the requirement of physical contact of the sensor with the sample, contamination and temperature monitoring at a single point. Here, we investigate the field induced heating of oil based oleic acid coated Fe3O4 nanofluid, synthesized using co-precipitation method, using infrared thermal imaging (IRT) camera and compare the results with those of fiber optic temperature sensor. Experiments were performed on nanofluid samples of four different concentrations and under five different external field amplitudes. The specific absorption rate (SAR) of the samples were determined from the initial rate of temperature rise measured using both the techniques. The SAR values determined from both the techniques were in very good agreement with each other, with in an accuracy of 5%, after incorporating convection loss correction on the infrared thermal imaging data. The consecutive thermal cycling on the samples showed good thermal stability and thermal recovery. The maximum SAR obtained was 95.9 W/gFe for a sample concentration and field amplitude of 23 wt.% and 57.3 kA m-1, respectively. This study showed the efficacy and accuracy of temperature measurement using IRT during field induced heating of magnetic nanofluid and its advantages over conventional point measurements techniques for real-time, non-contact and wide area temperature mapping without sample contamination.

  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. 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.

  14. 77 FR 60138 - Trinity Adaptive Management Working Group; Public Teleconference/Web-Based Meeting

    Science.gov (United States)

    2012-10-02

    ... Fish and Wildlife Service Trinity Adaptive Management Working Group; Public Teleconference/ Web-Based... Working Group (TAMWG). DATES: Teleconference/web-based meeting: Wednesday October 17, 2012, from 9 a.m. to... announce that the Trinity Adaptive Management Working Group (TAMWG) will hold a...

  15. 78 FR 17226 - Trinity Adaptive Management Working Group; Public Meeting, Teleconference and Web-Based Meeting

    Science.gov (United States)

    2013-03-20

    ... Fish and Wildlife Service Trinity Adaptive Management Working Group; Public Meeting, Teleconference and... Trinity Adaptive Management Working Group (TAMWG). DATES: Public meeting, Teleconference, and web-based... Management Working Group (TAMWG) will hold a teleconference/web-based meeting. Background The TAMWG...

  16. Study of smectite clays of the city Pedra Lavrada - PB for use in water-based drilling fluids; Estudo das argilas esmectiticas do municipio de Pedra Lavrada-PB para uso em fluidos de perfuracao base agua

    Energy Technology Data Exchange (ETDEWEB)

    Silva, I.A. da; Costa, J.M.R.; Cardoso, M.A.F.; Neves, G.A.; Ferreira, H.C., E-mail: isabelle_albuquerquecg@hotmail.com [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Ferreira, H.S. [Universidade Federal da Paraiba (DEMAT/CT/UFPB), Joao Pessoa, PB (Brazil)

    2011-07-01

    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)

  17. Water base drilling fluids for high-angle wells; Fluidos a base de agua para perfuracao de pocos com elevada inclinacao

    Energy Technology Data Exchange (ETDEWEB)

    Passarelli, Rui [PETROBRAS, Rio de Janeiro (Brazil). Dept. de Perfuracao. Div. de Fluidos de Perfuracao; Lomba, Rosana Fatima T. [PETROBRAS, Rio de Janeiro (Brazil). Centro de Pesquisas. Div. de Explotacao

    1989-12-31

    Horizontal drilling has experimented a large increase in last years. In Brazil, two horizontal wells were drilled in Fazenda Belem and Carmopolis Fields. The first one reached a final measured depth of 1128 m and the horizontal length was 533 m. The drilling fluid program was elaborated after a large number of laboratory tests, in order to get a composition that best fitted the drilling requirements, mainly the desirable lubricity. The idea of using a water-base fluid instead of an oil-based, known as more suitable in this case, arose because the Company is interested in drilling this kind of well offshore, in deep water, where the use of oil-base muds is forbidden. Different compositions of water base muds were developed and tested in laboratory and the results led to low-solids salt fluids having a lubricant in its composition. The lubricity coefficients of these fluids are similar to those obtained with oil-base muds. 9-FZB-446D-CE well was drilled with the chosen fluid and high values of torque and drag were not registered, being the operation a total success. (author) 10 tabs.

  18. Numerical simulation of blood flow and interstitial fluid pressure in solid tumor microcirculation based on tumor-induced angiogenesis

    Science.gov (United States)

    Zhao, Gaiping; Wu, Jie; Xu, Shixiong; Collins, M. W.; Long, Quan; König, Carola S.; Jiang, Yuping; Wang, Jian; Padhani, A. R.

    2007-10-01

    A coupled intravascular transvascular interstitial fluid flow model is developed to study the distributions of blood flow and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network. This is generated from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels. Blood flow through the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille’s law and Darcy’s law, respectively, transvascular flow is described by Starling’s law; effects of the vascular permeability and the interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial hypertension and low convection on the inside of the tumor, which are consistent with physiological observed facts. These results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.

  19. Ongoing Analyses of Rocket Based Combined Cycle Engines by the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center

    Science.gov (United States)

    Ruf, Joseph H.; Holt, James B.; Canabal, Francisco

    2001-01-01

    This paper presents the status of analyses on three Rocket Based Combined Cycle (RBCC) configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics (CFD) analysis on a Penn State RBCC test rig, the proposed Draco axisymmetric RBCC engine and the Trailblazer engine. The intent of the analysis on the Penn State test rig is to benchmark the Finite Difference Navier Stokes (FDNS) code for ejector mode fluid dynamics. The Draco analysis was a trade study to determine the ejector mode performance as a function of three engine design variables. The Trailblazer analysis is to evaluate the nozzle performance in scramjet mode. Results to date of each analysis are presented.

  20. Kidney injury, fluid, electrolyte and acid-base abnormalities in alcoholics.

    Science.gov (United States)

    Adewale, Adebayo; Ifudu, Onyekachi

    2014-03-01

    In the 21(st) century, alcoholism and the consequences of ethyl alcohol abuse are major public health concerns in the United States, affecting approximately 14 million people. Pertinent to the global impact of alcoholism is the World Health Organisation estimate that 140 million people worldwide suffer from alcohol dependence. Alcoholism and alcohol abuse are the third leading causes of preventable death in the United States. Alcohol dependence and alcohol abuse cost the United State an estimated US$220 billion in 2005, eclipsing the expense associated with cancer (US$196 billion) or obesity (US$133 billion). Orally ingested ethyl alcohol is absorbed rapidly without chemical change from the stomach and intestine, reaching maximum blood concentration in about an hour. Alcohol crosses capillary membranes by simple diffusion, affecting almost every organ system in the body by impacting a wide range of cellular functions. Alcohol causes metabolic derangements either directly, via its chemical by-product or secondarily through alcohol-induced disorders. Many of these alcohol-related metabolic disturbances are increased in severity by the malnutrition that is common in those with chronic alcoholism. This review focuses on the acute and chronic injurious consequences of alcohol ingestion on the kidney, as well as the fluid, electrolyte and acid-base abnormalities associated with acute and chronic ingestion of alcohol.

  1. Computational Fluid Dynamics (CFD-Based Droplet Size Estimates in Emulsification Equipment

    Directory of Open Access Journals (Sweden)

    Jo Janssen

    2016-12-01

    Full Text Available While academic literature shows steady progress in combining multi-phase computational fluid dynamics (CFD and population balance modelling (PBM of emulsification processes, the computational burden of this approach is still too large for routine use in industry. The challenge, thus, is to link a sufficiently detailed flow analysis to the droplet behavior in a way that is both physically relevant and computationally manageable. In this research article we propose the use of single-phase CFD to map out the local maximum stable droplet diameter within a given device, based on well-known academic droplet break-up studies in quasi-steady 2D linear flows. The results of the latter are represented by analytical correlations for the critical capillary number, which are valid across a wide viscosity ratio range. Additionally, we suggest a parameter to assess how good the assumption of quasi-steady 2D flow is locally. The approach is demonstrated for a common lab-scale rotor-stator device (Ultra-Turrax, IKA-Werke GmbH, Staufen, Germany. It is found to provide useful insights with minimal additional user coding and little increase in computational effort compared to the single-phase CFD simulations of the flow field, as such. Some suggestions for further development are briefly discussed.

  2. Shear time dependent viscosity of polystyrene-ethylacrylate based shear thickening fluid

    Science.gov (United States)

    Chen, Qian; Xuan, Shouhu; Jiang, Wanquan; Cao, Saisai; Gong, Xinglong

    2016-04-01

    In this study, the influence of the shear rate and shear time on the transient viscosity of polystyrene-ethylacrylate based shear thickening fluid (STF) is investigated. If the shear rate is stepwise changed, it is found that both the viscosity and critical shear rate are affected by the shear time. Above the critical shear rate, the viscosity of the STF with larger power law exponent (n) increases faster. However, the viscosity tends to decrease when the shear time is long enough. This phenomenon can be responsible for the reversible structure buildup and the break-down process. An effective volume fraction (EVF) mechanism is proposed to analyze the shear time dependent viscosity and it is found that viscosity changes in proportion to EVF. To further clarify the structure evolution, a structural kinetic model is studied because the structural kinetic parameter (λ) could describe the variation in the effective volume fraction. The theoretical results of the structural kinetic model agree well with the experimental results. With this model, the change in viscosity and EVF can be speculated from the variation of λ and then the structure evolution can be better illustrated.

  3. Numerical Characterization of the Performance of Fluid Pumps Based on a Wankel Geometry

    Directory of Open Access Journals (Sweden)

    Stephen Wan

    2014-01-01

    Full Text Available The performance of fluid pumps based on Wankel-type geometry, taking the shape of a double-lobed limaçon, is characterized. To the authors’ knowledge, this is the first time such an attempt has been made. To this end, numerous simulations for three different pump sizes were carried out and the results were understood in terms of the usual scaling coefficients. The results show that such pumps operate as low efficiency (<30% valveless positive displacements pumps, with pump flow-rate noticeably falling at the onset of internal leakage. Also, for such pumps, the mechanical efficiency varies linearly with the head coefficient, and, within the onset of internal leakage, the capacity coefficient holds steady even across pump efficiency. Simulation of the flow field reveals a structure rich in three-dimensional vortices even in the laminar regime, including Taylor-like counterrotating vortex pairs, pointing towards the utility of these pumps in microfluidic applications. Given the planar geometry of such pumps, their applications as microreactors and micromixers are recommended.

  4. Standard and high-throughput microfluidic disposables based on laminar fluid diffusion interfaces

    Science.gov (United States)

    Weigl, Bernhard H.; Morris, Chris; Kesler, Natasa; Battrell, Fred; Bardell, Ron L.

    2002-06-01

    Laminar Fluid Diffusion Interfaces are generated when tow or more streams flow in parallel in a microfluidic structure. This technology can be used for diffusion-based separation and detection applications, for example: DNA desalting, the extraction of small proteins from whole-blood samples, and the detection of various constituents in while blood. Additional applications are the establishment of stable concentration gradients, and the exposure of chemical constituents or biological particles to these concentration gradients, enabling the uniform and controlled exposure of cells to lysing agents, allowing the differentiation of cells by their sensitivity to specific agents in an on-chip cytometer coupled directly to the lysing structure. We have developed integrated systems using machine-controlled disposable cartridges and passive self-contained disposable cards including particle separators, flow cytometers, valves, detection channels, mixers, and diluters that are used in a hematology analyzer, stand-alone blood plasma separators, and a variety of chemical and biological assays. Microfluidic arrays compatible with common well-plate formats have been designed for high-throughout toxicology screening applications. All these devices were manufactured using Micronics' unique rapid-prototyping process yielding low-cost plastic disposable microfluidic chips.

  5. Two-dimensional intraventricular flow pattern visualization using the image-based computational fluid dynamics.

    Science.gov (United States)

    Doost, Siamak N; Zhong, Liang; Su, Boyang; Morsi, Yosry S

    2016-10-31

    The image-based computational fluid dynamics (IB-CFD) technique, as the combination of medical images and the CFD method, is utilized in this research to analyze the left ventricle (LV) hemodynamics. The research primarily aims to propose a semi-automated technique utilizing some freely available and commercial software packages in order to simulate the LV hemodynamics using the IB-CFD technique. In this research, moreover, two different physiological time-resolved 2D models of a patient-specific LV with two different types of aortic and mitral valves, including the orifice-type valves and integrated with rigid leaflets, are adopted to visualize the process of developing intraventricular vortex formation and propagation. The blood flow pattern over the whole cardiac cycle of two models is also compared to investigate the effect of utilizing different valve types in the process of the intraventricular vortex formation. Numerical findings indicate that the model with integrated valves can predict more complex intraventricular flow that can match better the physiological flow pattern in comparison to the orifice-type model.

  6. Evaluation of low toxicity mineral oil base drilling fluids; Avaliacao de fluidos de perfuracao a base de oleo mineral de baixa toxidez

    Energy Technology Data Exchange (ETDEWEB)

    Ponte, Ielton Frederico da [PETROBRAS, Rio de Janeiro (Brazil). Centro de Pesquisas. Div. de Explotacao

    1989-12-31

    In order to introduce low toxicity mineral oil base drilling fluids in Brazil, we carried out a series with a low aromatic content basic oil for lubricants, produced by PETROBRAS: the Lubrax Industrial OB-9 (Lubind OB-9). This oil, as well as its mixture with aviation kerosene to reduce viscosity, was found adequate for use in drilling fluids together with other national products developed by companies that supply additives for drilling fluids in Brazil. We present the results of laboratory tests with systems of four different manufacturers, one of which was chosen for initial field tests. These tests, which were carried out at the Miranga and Bu River Fields, in the Drilling District of Bahia, produced satisfactory results. We anticipate the use of these fluids in other areas where the company operates. (author) 2 refs., 3 tabs.

  7. Refrigerating fluids; Fluides frigorigenes

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1999-03-01

    Refrigerating fluids are experiencing a real revolution since few years. CFCs with their destructive effect on the ozone layer are now prohibited while HCFCs will be progressively eliminated and replaced by HFCs. However, HFCs can contribute to the increase of the greenhouse effect. The solutions proposed by thermal engineering professionals consist in the confinement of air-conditioning installations (elimination of recurrent leaks) and in the improvement of installations efficiency. HCFC fluids like the R 22 are still widely used in air-conditioning but they are supposed to be replaced by HFC fluids like the R 134a, the R 407C or the R 410A. This short paper gives a brief presentation of these fluids and of their chemical characteristics. (J.S.)

  8. Development and Verification of a Pilot Code based on Two-fluid Three-field Model

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Moon Kyu; Bae, S. W.; Lee, Y. J.; Chung, B. D.; Jeong, J. J.; Ha, K. S.; Kang, D. H

    2006-09-15

    In this study, a semi-implicit pilot code is developed for a one-dimensional channel flow as three-fields. The three fields are comprised of a gas, continuous liquid and entrained liquid fields. All the three fields are allowed to have their own velocities. The temperatures of the continuous liquid and the entrained liquid are, however, assumed to be equilibrium. The interphase phenomena include heat and mass transfer, as well as momentum transfer. The fluid/structure interaction, generally, include both heat and momentum transfer. Assuming adiabatic system, only momentum transfer is considered in this study, leaving the wall heat transfer for the future study. Using 10 conceptual problems, the basic pilot code has been verified. The results of the verification are summarized below: It was confirmed that the basic pilot code can simulate various flow conditions (such as single-phase liquid flow, bubbly flow, slug/churn turbulent flow, annular-mist flow, and single-phase vapor flow) and transitions of the flow conditions. The pilot code was programmed so that the source terms of the governing equations and numerical solution schemes can be easily tested. The mass and energy conservation was confirmed for single-phase liquid and single-phase vapor flows. It was confirmed that the inlet pressure and velocity boundary conditions work properly. It was confirmed that, for single- and two-phase flows, the velocity and temperature of non-existing phase are calculated as intended. Complete phase depletion which might occur during a phase change was found to adversely affect the code stability. A further study would be required to enhance code capability in this regard.

  9. Correlation of Critical Loci for Water-Hydrocarbon Binary Systems by EOS Based on the Multi-Fluid Nonrandom Lattice Theory

    Institute of Scientific and Technical Information of China (English)

    Hun; Yong; SHIN; Hwayong; KIM; 等

    2002-01-01

    Quantitative representation of complicated behavior of fluid mixtures in the critical region by any of equation-of-state theories remains as a difficults thermodynamic topics to date.In the present work,a computational efforts were made for representing various types of critical loci of binary water with hydrocarbon systems showing Type Ⅱ and Type Ⅲ phase behavior by an elementary equation of state[called multi-fluid nonrandom lattice fluid EOS(MF-NLF EOS)]based on the lattice statistical mechanical theory.The model EOS requires two molecular parameters which representing molecular size and interaction energy for a pure component and single adjustable interaction energy parameter for binary mixtures.Critical temperature and pressure data were used to obtain molecular size parameter and vapor pressure data were used to obtain interaction energy parameter.The MF-NLF EOS model adapted in the present study correlated quantitatively well the critical loci of various binary water with hydrocarbon systems.

  10. Group contribution methodology based on the statistical associating fluid theory for heteronuclear molecules formed from Mie segments.

    Science.gov (United States)

    Papaioannou, Vasileios; Lafitte, Thomas; Avendaño, Carlos; Adjiman, Claire S; Jackson, George; Müller, Erich A; Galindo, Amparo

    2014-02-07

    A generalization of the recent version of the statistical associating fluid theory for variable range Mie potentials [Lafitte et al., J. Chem. Phys. 139, 154504 (2013)] is formulated within the framework of a group contribution approach (SAFT-γ Mie). Molecules are represented as comprising distinct functional (chemical) groups based on a fused heteronuclear molecular model, where the interactions between segments are described with the Mie (generalized Lennard-Jonesium) potential of variable attractive and repulsive range. A key feature of the new theory is the accurate description of the monomeric group-group interactions by application of a high-temperature perturbation expansion up to third order. The capabilities of the SAFT-γ Mie approach are exemplified by studying the thermodynamic properties of two chemical families, the n-alkanes and the n-alkyl esters, by developing parameters for the methyl, methylene, and carboxylate functional groups (CH3, CH2, and COO). The approach is shown to describe accurately the fluid-phase behavior of the compounds considered with absolute average deviations of 1.20% and 0.42% for the vapor pressure and saturated liquid density, respectively, which represents a clear improvement over other existing SAFT-based group contribution approaches. The use of Mie potentials to describe the group-group interaction is shown to allow accurate simultaneous descriptions of the fluid-phase behavior and second-order thermodynamic derivative properties of the pure fluids based on a single set of group parameters. Furthermore, the application of the perturbation expansion to third order for the description of the reference monomeric fluid improves the predictions of the theory for the fluid-phase behavior of pure components in the near-critical region. The predictive capabilities of the approach stem from its formulation within a group-contribution formalism: predictions of the fluid-phase behavior and thermodynamic derivative properties of

  11. Magnetic fluid based squeeze film between porous circular disks with sealed boundary

    Institute of Scientific and Technical Information of China (English)

    R.M.PATEL; G.M.DEHERI

    2001-01-01

    Efforts have been made to study the effect of the magnetic fluid lubricant and the seal-ing of the boundary for the squeeze film between two circular disks when the upper disk having aporous facing with its boundary sealed, approaches the non-porous lower disk normally. The modi-fied Reynolds equations for the fluid region and the governing Laplacian equation for the pressurein porous region are solved with appropriate boundary conditions. Expressions are obtained forpressure, load carrying capacity and the response time. The results are presented graphically. Thecombined effect of the magnetic fluid lubricant and sealing of the boundary increases the load car-rying capacity significantly and hence the performance of the bearing can be enhanced considera-bly by sealing the boundary and taking a magnetic fluid as lubricant.

  12. Preparation of Chitosan-Based Hemostatic Sponges by Supercritical Fluid Technology

    Directory of Open Access Journals (Sweden)

    Hu-Fan Song

    2014-03-01

    Full Text Available Using ammonium bicarbonate (AB particles as a porogen, chitosan (CS-based hemostatic porous sponges were prepared in supercritical carbon dioxide due to its low viscosity, small surface tension, and good compatibility with organic solvent. Fourier transform infrared spectroscopy (FTIR spectra demonstrated that the chemical compositions of CS and poly-(methyl vinyl ether-co-maleic anhydride (PVM/MA were not altered during the phase inversion process. The morphology and structure of the sponge after the supercritical fluid (SCF process were observed by scanning electron microscopy (SEM. The resulting hemostatic sponges showed a relatively high porosity (about 80% with a controllable pore size ranging from 0.1 to 200 µm. The concentration of PVM/MA had no significant influence on the porosity of the sponges. Comparative experiments on biological assessment and hemostatic effect between the resulting sponges and Avitene® were also carried out. With the incorporation of PVM/MA into the CS-based sponges, the water absorption rate of the sponges increased significantly, and the CS-PVM/MA sponges showed a similar water absorption rate (about 90% to that of Avitene®. The results of the whole blood clotting experiment and animal experiment also demonstrated that the clotting ability of the CS-PVM/MA sponges was similar to that of Avitene®. All these results elementarily verified that the sponges prepared in this study were suitable for hemostasis and demonstrated the feasibility of using SCF-assisted phase inversion technology to produce hemostatic porous sponges.

  13. [The status of acid-base homeostasis in oral fluid during gestation].

    Science.gov (United States)

    Pol'ovyĭ, P V

    2013-01-01

    The article presents information on the nature and dynamics of metabolic changes in oral fluid in women during gestation. It is shown that dystrophic-inflammatory processes of periodontal tissues grow backed by the progression of metabolic acidosis. High content of sulfhydryl groups and disulfide ties in soluble proteins and low molecular weight compounds of oral fluid during pregnancy and activation of enzymatic antioxidant defense system periodontal tissues are found.

  14. Water and clay based drilling fluids: rheologic, filtration and lubricity behavior; Fluidos hidroargilosos: comportamento reologico, de filtracao e lubricidade

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana V.; Pereira, Melquesedek S.; Ferreira, Heber C. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2008-07-01

    The aim of this work is to provide continuity for UFCG studies presenting results of rheological, filtration and the lubricity behaviors obtained with fluids prepared with bentonite clays from Paraiba, in binary compositions, after treatment with lubricants agents. It was selected two samples of bentonite clays and four lubricants (Lub 1, Lub 2, Lub 3 and Lub 4). The results showed that: depending on the composition, the drilling fluids presented bingham and pseudo plastic rheological behaviors, and with the additives bingham behavior; among the rheological and filtration properties evaluated, the apparent viscosity, yield limiting and the water loss are the have changes with the addition of lubricants; the values of the lubricity coefficient (LC) of fluids without additives were next of 0.50, independent of the composition of the bentonite clay mixture; after addition of the lubricants, the LC of fluids reduced for values next to 0,11, independent of its concentration and lubricants the best-performing are the Lub 2 and Lub 4. (author)

  15. Fully automated dialysis system based on the central dialysis fluid delivery system.

    Science.gov (United States)

    Kawanishi, Hideki; Moriishi, Misaki; Sato, Takashi; Taoka, Masahiro

    2009-01-01

    The fully automated dialysis system (FADS) was developed as an improvement over previous patient monitors used in the treatment of hemodialysis, with the aim of standardizing and promoting labor-saving in such treatment. This system uses backfiltration dialysis fluid to perform priming, blood rinse back and rapid fluid replenishment, and causes guiding of blood into the dialyzer by the drainage pump for ultrafiltration. This requires that the dialysis fluid used be purified to a high level. The central dialysis fluid delivery system (CDDS) combines the process of the creation and supply of dialysis water and dialysis fluid to achieve a level of purity equivalent with ultrapure dialysis fluid. FADS has the further advantages of greater efficiency and streamlined operation, reducing human error and the risk of infection without requiring the storage or disposal of normal saline solution. The simplification of hemodialysis allows for greater frequency of dialysis or extended dialysis, enabling treatment to be provided in line with the patient's particular situation. FADS thus markedly improves the reliability, safety and standardization of dialysis procedures while ensuring labor-saving in these procedures, making it of particular utility for institutions dealing with dialysis on a large scale.

  16. Fully Coupled Fluid-Structure Interaction Model Based on Distributed Lagrange Multiplier/Fictitious Domain Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper, with a finite element method, studies the interaction of a coupled incompressible fluid-rigid structure system with a free surface subjected to external wave excitations. With this fully coupled model, the rigid structure is taken as "fictitious" fluid with zero strain rate. Both fluid and structure are described by velocity and pressure. The whole domain, including fluid region and structure region, is modeled by the incompressible Navier-Stokes equations which are discretized with fixed Eulerian mesh. However, to keep the structure's rigid body shape and behavior, a rigid body constraint is enforced on the "fictitious" fluid domain by use of the Distributed Lagrange Multiplier/Fictitious Domain (DLM/FD) method which is originally introduced to solve particulate flow problems by Glowinski et al. For the verification of the model presented herein, a 2D numerical wave tank is established to simulate small amplitude wave propagations, and then numerical results are compared with analytical solutions. Finally, a 2D example of fluid-structure interaction under wave dynamic forces provides convincing evidences for the method excellent solution quality and fidelity.

  17. Magnetoviscous effect of ferrite-based magnetic fluid for EOR application

    Science.gov (United States)

    Latiff, Noor Rasyada Ahmad; Soleimani, Hassan; Zaid, Hasnah Mohd; Adil, Muhammad

    2016-11-01

    Magnetic fluid is proposed as a substitute for the application of polymer solution as a means to recover the residual oil left in the bypassed region in oil reservoirs. When subjected to magnetic field, the viscosity of magnetic fluids increases and enable flow control. In this study, the response of magnetic nanofluid with the applied magnetic field was observed as a function of shear rate. Two types of samples, namely magnetite and cobalt ferrite of 0.1% w/v of different polydispersity index, saturation magnetization and mean hydrodynamic particle size were used. The strength of the applied magnetic field was also varied to investigate the effect of magnetic field strength on the viscosity enhancement of magnetic fluid. Shear dependence response of the magnetic fluid exhibit non-Newtonian behavior when magnetic field of 20 to 40 mT was applied. Viscosity of the magnetic fluid reduced with increasing shear rates, showing shear thinning behavior. At a particular shear rate, viscosity remains constant when the strength of magnetic field increases indicating saturation in chain length even at low field. Magnetoviscous effect (MVE) is calculated as an indicator for a viscosity gain magnitude when magnetic field is applied. Cobalt ferrite sample shows larger MVE compared to magnetite that may be attributed to the higher polydispersity index. In conclusion, particle size distribution is the most dominant factor affecting MVE of the dilute magnetic fluid when magnetic field is applied.

  18. Corrosion in supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Propp, W.A.; Carleson, T.E.; Wai, Chen M.; Taylor, P.R.; Daehling, K.W.; Huang, Shaoping; Abdel-Latif, M.

    1996-05-01

    Integrated studies were carried out in the areas of corrosion, thermodynamic modeling, and electrochemistry under pressure and temperature conditions appropriate for potential applications of supercritical fluid (SCF) extractive metallurgy. Carbon dioxide and water were the primary fluids studied. Modifiers were used in some tests; these consisted of 1 wt% water and 10 wt% methanol for carbon dioxide and of sulfuric acid, sodium sulfate, ammonium sulfate, and ammonium nitrate at concentrations ranging from 0.00517 to 0.010 M for the aqueous fluids. The materials studied were Types 304 and 316 (UNS S30400 and S31600) stainless steel, iron, and AISI-SAE 1080 (UNS G10800) carbon steel. The thermodynamic modeling consisted of development of a personal computer-based program for generating Pourbaix diagrams at supercritical conditions in aqueous systems. As part of the model, a general method for extrapolating entropies and related thermodynamic properties from ambient to SCF conditions was developed. The experimental work was used as a tool to evaluate the predictions of the model for these systems. The model predicted a general loss of passivation in iron-based alloys at SCF conditions that was consistent with experimentally measured corrosion rates and open circuit potentials. For carbon-dioxide-based SCFs, measured corrosion rates were low, indicating that carbon steel would be suitable for use with unmodified carbon dioxide, while Type 304 stainless steel would be suitable for use with water or methanol as modifiers.

  19. Analysis of the Properties of Working Substances for the Organic Rankine Cycle based Database “REFPROP”

    Directory of Open Access Journals (Sweden)

    Galashov Nikolay

    2016-01-01

    Full Text Available The object of the study are substances that are used as a working fluid in systems operating on the basis of an organic Rankine cycle. The purpose of research is to find substances with the best thermodynamic, thermal and environmental properties. Research conducted on the basis of the analysis of thermodynamic and thermal properties of substances from the base “REFPROP” and with the help of numerical simulation of combined-cycle plant utilization triple cycle, where the lower cycle is an organic Rankine cycle. Base “REFPROP” describes and allows to calculate the thermodynamic and thermophysical parameters of most of the main substances used in production processes. On the basis of scientific publications on the use of working fluids in an organic Rankine cycle analysis were selected ozone-friendly low-boiling substances: ammonia, butane, pentane and Freon: R134a, R152a, R236fa and R245fa. For these substances have been identified and tabulated molecular weight, temperature of the triple point, boiling point, at atmospheric pressure, the parameters of the critical point, the value of the derivative of the temperature on the entropy of the saturated vapor line and the potential ozone depletion and global warming. It was also identified and tabulated thermodynamic and thermophysical parameters of the steam and liquid substances in a state of saturation at a temperature of 15 °C. This temperature is adopted as the minimum temperature of heat removal in the Rankine cycle when working on the water. Studies have shown that the best thermodynamic, thermal and environmental properties of the considered substances are pentane, butane and R245fa. For a more thorough analysis based on a gas turbine plant NK-36ST it has developed a mathematical model of combined cycle gas turbine (CCGT triple cycle, where the lower cycle is an organic Rankine cycle, and is used as the air cooler condenser. Air condenser allows stating material at a temperature

  20. The Impact of a Pulmonary-Artery-Catheter-Based Protocol on Fluid and Catecholamine Administration in Early Sepsis

    Directory of Open Access Journals (Sweden)

    Carina Bethlehem

    2012-01-01

    Full Text Available Objective. The pulmonary artery catheter (PAC remains topic of debate. Despite abundant data, it is of note that many trials did not incorporate a treatment protocol. Methods. We retrospectively evaluated fluid balances and catecholamine doses in septic patients after the introduction of a PAC-based treatment protocol in comparison to historic controls. Results. 2×70 patients were included. The first day the PAC group had a significantly higher positive fluid balance in comparison to controls (6.1±2.6 versus 3.8±2.4 litre, <0.001. After 7 days the cumulative fluid balance in the PAC group was significantly lower than in controls (9.4±7.4 versus 13±7.6 litre, =0.001. Maximum dose of norepinephrine was significantly higher in the PAC group. Compared to controls this was associated with a significant reduction in ventilator and ICU days. Conclusions. Introduction of a PAC-based treatment protocol in sepsis changed the administration of fluid and vasopressors significantly.

  1. Novel hydrophobic associated polymer based nano-silica composite with core–shell structure for intelligent drilling fluid under ultra-high temperature and ultra-high pressure

    Directory of Open Access Journals (Sweden)

    Hui Mao

    2015-02-01

    Full Text Available Micro-nano-based drilling fluid has attracted a strong interest due to its attractive properties, and micro-nano composite materials have great potential for developing intelligent drilling fluid. In this study a novel hydrophobic associated polymer based nano-silica composite with core–shell structure was prepared and characterized by PSD, SEM, TEM and ESEM. The results showed that the composite, as a micro-nano drilling fluid additive, possessed excellent properties such as thermal stability, rheology, fluid loss and lubricity. Especially, it could plug the formation effectively and improve the pressure bearing capability of formation significantly.

  2. Two-Fluid Equilibrium for Transonic Poloidal Flows

    Science.gov (United States)

    Guazzotto, Luca; Betti, Riccardo

    2012-03-01

    Much analytical and numerical work has been done in the past on ideal MHD equilibrium in the presence of macroscopic flow. In recent years, several authors have worked on equilibrium formulations for a two-fluid system, in which inertial ions and massless electrons are treated as distinct fluids. In this work, we present our approach to the formulation of the two-fluid equilibrium problem. Particular attention is given to the relation between the two-fluid equations and the equilibrium equations for the single-fluid ideal MHD system. Our purpose is to reconsider the results of one-fluid calculation with the more accurate two-fluid model, referring in particular to the so-called transonic discontinuities, which occur when the poloidal velocity spans a range crossing the poloidal sound speed (i.e., the sound speed reduced by a factor Bp/B). It is expected that the one-fluid discontinuity will be resolved into a sharp gradient region by the two-fluid model. Also, contrary to the ideal MHD case, in the two-fluid model the equations governing the equilibrium are elliptic in the whole range of interest for transonic equilibria. The numerical solution of the two-fluid system of equations is going to be based on a code built on the structure of the existing ideal-MHD code FLOW.

  3. GWAS-based pathway analysis differentiates between fluid and crystallized intelligence.

    Science.gov (United States)

    Christoforou, A; Espeseth, T; Davies, G; Fernandes, C P D; Giddaluru, S; Mattheisen, M; Tenesa, A; Harris, S E; Liewald, D C; Payton, A; Ollier, W; Horan, M; Pendleton, N; Haggarty, P; Djurovic, S; Herms, S; Hoffman, P; Cichon, S; Starr, J M; Lundervold, A; Reinvang, I; Steen, V M; Deary, I J; Le Hellard, S

    2014-09-01

    Cognitive abilities vary among people. About 40-50% of this variability is due to general intelligence (g), which reflects the positive correlation among individuals' scores on diverse cognitive ability tests. g is positively correlated with many life outcomes, such as education, occupational status and health, motivating the investigation of its underlying biology. In psychometric research, a distinction is made between general fluid intelligence (gF) - the ability to reason in novel situations - and general crystallized intelligence (gC) - the ability to apply acquired knowledge. This distinction is supported by developmental and cognitive neuroscience studies. Classical epidemiological studies and recent genome-wide association studies (GWASs) have established that these cognitive traits have a large genetic component. However, no robust genetic associations have been published thus far due largely to the known polygenic nature of these traits and insufficient sample sizes. Here, using two GWAS datasets, in which the polygenicity of gF and gC traits was previously confirmed, a gene- and pathway-based approach was undertaken with the aim of characterizing and differentiating their genetic architecture. Pathway analysis, using genes selected on the basis of relaxed criteria, revealed notable differences between these two traits. gF appeared to be characterized by genes affecting the quantity and quality of neurons and therefore neuronal efficiency, whereas long-term depression (LTD) seemed to underlie gC. Thus, this study supports the gF-gC distinction at the genetic level and identifies functional annotations and pathways worthy of further investigation.

  4. Alkaline phosphatase inhibition based conductometric biosensor for phosphate estimation in biological fluids.

    Science.gov (United States)

    Upadhyay, Lata Sheo Bachan; Verma, Nishant

    2015-06-15

    Determination of phosphate ions concentration is very important from both, environmental and clinical point of view. In this study, a simple and novel conductometric biosensor for indirect determination of the phosphate ions in aqueous solution has been developed. The developed biosensor is based on the inhibition of immobilized alkaline phosphatase activity, in the presence of the phosphate ions. This is the first time we developed a mono-enzymatic biosensor for indirect estimation of phosphate ions. The developed biosensor showed a broad linear response (as compared to other reported biosensors) for phosphate ions in the range of 0.5-5.0 mM (correlation coefficient=0.995), with a detection limit of 50 µM. Different optimized parameters were obtained as the buffer concentration of 30 mM, substrate concentration of 1.0mM, and a pH of 9.0. All the optimized parameters were analyzed by analysis of variance, and were found to be statistically significant at a level of α=0.05. The developed biosensor is also suitable to determine the serum phosphate concentration, with a recovery of 86-104%, while a recovery of 102% was obtained from the water samples that were spiked with 500 µM phosphate. A relative standard deviation in the conductance response for five successive measurements (n=5) did not exceed 7%, with a shelf life of 30 days. With a lower detection limit and a higher recovery, the biosensor provides a facile approach for phosphate estimation in biological fluids.

  5. CMC use as colloid protector in water and clay basis drilling fluids: part II; Uso do CMC como coloide protetor em fluidos de perfuracao a base de agua e argilas: parte II

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana Viana [Universidade Federal, Campina Grande, PB (Brazil). Engenharia de Processos]. E-mail: lucianaa@labdes.ufpb.br; Viana, Josiane Dantas; Farias, Kassie Vieira; Lira, Helio de Lucena; Ferreira, Heber Carlos [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia de Materiais]. E-mail: josianedantas@bol.com.br; kassievieira@bol.com.br; helio@dema.ufpb.br; heber@dema.ufpb.br; Franca, Kepler Borges [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Eng. Quimica]. E-mail: kepler@labdes.ufpb.br

    2003-07-01

    The aim of this work is to study the protect effect of the low viscosity carboxymethyl cellulose (CMC) on water based oil well drilling fluids and bentonite clays treated with sodium, additivated with degrading agents. The drilling fluids were prepared with a concentration of 4.86% w/w, according to PETROBRAS norms. It was studied three samples of natural bentonite clays treated with Na{sub 2}CO{sub 3}, from Boa Vista, PB. The drilling fluids were treated with three different concentration of CMC and submitted to a cure for a period of 24 hours. After it were added degrading agents (CaCl{sub 2} + MgCl{sub 2}). Also, it was done the treatment in a reverse order, i.e., first the drilling fluids were treated with degrading agents and after with CMC. It was measured apparent viscosity (AV), plastic viscosity (PV) by using a Fann Viscosimeter and water loss (WL), by using a Fann filter press. The results showed that CMC protect the drilling fluids from the flocculating effect of calcium and magnesium and stop the damage caused by degrading agents. Also, the order of the treatment (degrading agent - CMC) does not present significant influence in the rheological properties of the studied drilling fluids. (author)

  6. Study on some rheological parameters of water and clay basis drilling fluids additivated with industrial sodium silicate; Estudo de alguns parametros reologicos de fluidos de perfuracao a base de agua e argila aditivados com silicato de sodio industrial

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana Viana [Universidade Federal, Campina Grande, PB (Brazil). Engenharia de Processos]. E-mail: lucianaa@labdes.ufpb.br; Viana, Josiane Dantas; Farias, Kassie Vieira [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia de Materiais]. E-mail: josianedantas@bol.com.br; kassievieira@bol.com.br; Franca, Kepler Borges; Lira, Helio de Lucena; Ferreira, Heber Carlos [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Eng. Quimica]. E-mail: kepler@labdes.ufpb.br; helio@dema.ufpb.br; heber@dema.ufpb.br

    2003-07-01

    The aim of this work is to study some rheological parameters of water based oil well drilling fluids and bentonite clay from Boa Vista, PB, treated with industrial sodium silicate. It were selected there samples of natural polycationic bentonite clays and four industrial sodium bentonite clays. The natural clays were treated with concentrated Na{sub 2}CO{sub 3} solution. The drilling fluids were prepared with concentration of 4.86% w/w, according to PETROBRAS norms, and additivated with four different concentration of industrial sodium silicate. After 24 hours of cure, it were measured apparent viscosity (AV) and plastic viscosity (PV) by using a Fann 35A viscosimeter and water loss (WL) by using a Fann filter press. The results showed a change in the rheology of the drilling fluids. The drilling fluids prepared with industrialized clays showed a decrease in AV and an increase in WL. For the drilling fluids prepared with natural clays treated with Na{sub 2}CO{sub 3}, it was observed a decrease in AV and WL and an increase in PV. Also, it was observed a change in the drilling fluids state from flocculated-gel to a partially flocculated. (author)

  7. Amniotic Fluid Stem Cells and Their Application in Cell-Based Tissue Regeneration

    Directory of Open Access Journals (Sweden)

    Mohamadreza Baghaban Eslaminejad

    2012-01-01

    Full Text Available Advances in stem cell biotechnology hold great promise in the field of tissue engineering andregenerative medicine. Of interest are marrow mesenchymal stem cells (MSCs, embryonic stemcells (ESCs, and induced pluripotent stem cells (iPSCs. In addition, amniotic fluid stem cells (AFSCshave attracted attention as a viable choice following the search for an alternative stem cellsource. Investigators are interested in these cells because they come from the amniotic fluid that isroutinely discarded after birth. There have been multiple investigations conducted worldwide in anattempt to better understand AF-SCs in terms of their potential use in regenerative medicine. In thisreview we give a brief introduction of amniotic fluid followed by a description of the cells presentwithin this fluid. Their history related to stem cell discovery in the amniotic fluid as well as themain characteristics of AF-SCs are discussed. Finally, we elaborate on the potential for these cellsto promote regeneration of various tissue defects, including fetal tissue, the nervous system, heart,lungs, kidneys, bones, and cartilage.

  8. Rheological Properties of a Honge Oil-based Magnetorheological Fluid used as Carrier Liquid (Review Paper

    Directory of Open Access Journals (Sweden)

    Gangadhara Shetty B

    2011-10-01

    Full Text Available Developing a sudden damping and its control which is demanded in many engineering applications with the existing conventional methods are difficult and critical too. A magnetorheological (MR fluid with good rheological properties can exhibit very fast damping characteristics and can be controlled just by varying the applied magnetic field to that fluid. Thus in this paper, a MR fluid is proposed with a non-edible vegetable oil such as Honge oil as a carrier liquid. Three samples of such MR fluid containing different percentages by volume of carbonyl iron powder as suspensions are prepared for comparing their rheological properties. An experimental setup consisting of a capillary viscometer with a pair of solenoid type of electromagnetic coils is developed. The rheological properties of the proposed MR fluid are investigated under the application of different magnetic fields and the results are presented. It was observed that the one of the samples containing 40 per cent by volume as suspensions exhibits a maximum viscosity of 334 Pa-s and yield stress of 13.23 kPa at a magnetic field of 0.3816 T. The results have been compared with those obtained by other researchers.Defence Science Journal, 2011, 61(6, pp.583-589, DOI:http://dx.doi.org/10.14429/dsj.61.331

  9. Study on an alternating current electrothermal micropump for microneedle-based fluid delivery systems

    Science.gov (United States)

    Zhang, Rumi; Jullien, Graham A.; Dalton, Colin

    2013-07-01

    In this paper, we report on a modeling study of an AC electrothermal (ACET) micropump with high operating pressures as well as fast flow rates. One specific application area is for fluid delivery using microneedle arrays which require higher pressures and faster flow rates than have been previously reported with ACET devices. ACET is very suitable for accurate actuation and control of fluid flow, since the technique has been shown to be very effective in high conductivity fluids and has the ability to create a pulsation free flow. However, AC electrokinetic pumps usually can only generate low operating pressures of 1 to 100 Pa, where flow reversal is likely to occur with an external load. In order to realize a high performance ACET micropump for continuous fluid delivery, applying relatively high AC operating voltages (20 to 36 Vrms) to silicon substrate ACET actuators and using long serpentine channel allows the boosting of operating pressure as well as increasing the flow rates. Fast pumping flow rates (102-103 nl/s) and high operating pressures (1-12 kPa) can be achieved by applying both methods, making them of significant importance for continuous fluid delivery applications using microneedle arrays and other such biomedical devices.

  10. Examining Inclusion of Evidence-Based Practice on Social Work Training Program Websites

    Science.gov (United States)

    Wike, Traci L.; Bledsoe, Sarah E.; Bellamy, Jennifer L.; Grady, Melissa D.

    2013-01-01

    Websites represent a visible medium for social work programs to communicate information about social work research, academics, and professional training priorities, including evidence-based practice (EBP). However, few studies have examined the content of social work program websites. This exploratory study aimed to answer the question: Are EBP…

  11. Integrating Social Neuroscience and Social Work: Innovations for Advancing Practice-Based Research

    Science.gov (United States)

    Matto, Holly C.; Strolin-Goltzman, Jessica

    2010-01-01

    Throughout the social work profession, there is ongoing interest in building a social science agenda that can address the complex practice-based questions faced by social work professionals today. Methodological innovations and unique funding opportunities have already significantly advanced research on social work practice. Still, there is…

  12. Problem-Based Learning in Social Work Education: Students' Experiences in Denmark

    Science.gov (United States)

    Monrad, Merete; Mølholt, Anne-Kirstine

    2017-01-01

    Problem-based learning (PBL) constitutes a promising way of integrating academia and social work practice because PBL fosters engagement with real-life problems and enhances important skills needed in social work practice. However, little attention has been given to social work students' experiences of PBL. In this article we address this gap by…

  13. A longitudinal study of higher-order thinking skills: working memory and fluid reasoning in childhood enhance complex problem solving in adolescence.

    Science.gov (United States)

    Greiff, Samuel; Wüstenberg, Sascha; Goetz, Thomas; Vainikainen, Mari-Pauliina; Hautamäki, Jarkko; Bornstein, Marc H

    2015-01-01

    Scientists have studied the development of the human mind for decades and have accumulated an impressive number of empirical studies that have provided ample support for the notion that early cognitive performance during infancy and childhood is an important predictor of later cognitive performance during adulthood. As children move from childhood into adolescence, their mental development increasingly involves higher-order cognitive skills that are crucial for successful planning, decision-making, and problem solving skills. However, few studies have employed higher-order thinking skills such as complex problem solving (CPS) as developmental outcomes in adolescents. To fill this gap, we tested a longitudinal developmental model in a sample of 2,021 Finnish sixth grade students (M = 12.41 years, SD = 0.52; 1,041 female, 978 male, 2 missing sex). We assessed working memory (WM) and fluid reasoning (FR) at age 12 as predictors of two CPS dimensions: knowledge acquisition and knowledge application. We further assessed students' CPS performance 3 years later as a developmental outcome (N = 1696; M = 15.22 years, SD = 0.43; 867 female, 829 male). Missing data partly occurred due to dropout and technical problems during the first days of testing and varied across indicators and time with a mean of 27.2%. Results revealed that FR was a strong predictor of both CPS dimensions, whereas WM exhibited only a small influence on one of the two CPS dimensions. These results provide strong support for the view that CPS involves FR and, to a lesser extent, WM in childhood and from there evolves into an increasingly complex structure of higher-order cognitive skills in adolescence.

  14. A robust algorithm for moving interface of multi-material fluids based on Riemann solutions

    Institute of Scientific and Technical Information of China (English)

    Xueying Zhang; Ning Zhao

    2006-01-01

    In the paper,the numerical simulation of interface problems for multiple material fluids is studied.The level set function is designed to capture the location of the material interface.For multi-dimensional and multi-material fluids,the modified ghost fluid method needs a Riemann solution to renew the variable states near the interface.Here we present a new convenient and effective algorithm for solving the Riemann problem in the normal direction.The extrapolated variables are populated by Taylor series expansions in the direction.The anti-diffusive high order WENO difference scheme with the limiter is adopted for the numerical simulation.Finally we implement a series of numerical experiments of multi-material flows.The obtained results are satisfying,compared to those by other methods.

  15. Magnetite-cobalt ferrite nanoparticles for kerosene-based magnetic fluids

    Energy Technology Data Exchange (ETDEWEB)

    Ayala-Valenzuela, O. [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes Saavedra No. 120, Complejo Industrial Chihuahua, Chihuahua, Chih. (Mexico) and Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 140 CP 25000 Saltillo, Coahuila (Mexico)]. E-mail: oscar.ayala@cimav.edu.mx; Matutes-Aquino, J. [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes Saavedra No. 120, Complejo Industrial Chihuahua, Chihuahua, Chih. (Mexico); Betancourt-Galindo, R. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 140 CP 25000 Saltillo, Coahuila (Mexico); Garcia-Cerda, L.A. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 140 CP 25000 Saltillo, Coahuila (Mexico); Rodriguez Fernandez, O. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 140 CP 25000 Saltillo, Coahuila (Mexico); Fannin, P.C. [Department of Electronic and Electrical Engineering, Trinity College, Dublin 2 (Ireland); Giannitsis, A.T. [Department of Electronic and Electrical Engineering, Trinity College, Dublin 2 (Ireland)

    2005-07-15

    Due to the magnetic anisotropy introduced by the Co{sup 2+} ion in octahedral sites of cubic spinel ferrites, it is possible to tailor the magnetic properties by changing the cobalt content. Magnetic fluids with magnetite-cobalt ferrite nanoparticles given by the formula Co{sub (} {sub x} {sub )}Fe{sub (3-} {sub x} {sub )}O{sub 4} with x=0, 0.2 and 0.4 were prepared. Kerosene and oleic acid were used as liquid carrier and surfactant, respectively. Spherical magnetic nanoparticles were obtained by coprecipitation from metal salts and ammonium hydroxide; afterwards the magnetic fluids were obtained by a peptization process. Powder properties were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherma (BET), vibrating sample magnetometry (VSM) and fluids by transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), VSM and the short-circuited transmission line technique.

  16. Research on the Influence of the Working Fluid Conductivity on MSWEDM Process Indicators%工作液电导率对MSWEDM加工工艺性指标影响研究

    Institute of Scientific and Technical Information of China (English)

    郭翠霞; 刘康; 谢文玲; 周顺勇

    2014-01-01

    The influence of the working fluid conductivity on the multiple cutting process of MSWEDM was studied through ex-periments.The influence of the working fluid conductivity on machining states (machining voltage,machining current)and the influ-ence of the working fluid conductivity on the cutting speed,surface roughness and machining accuracy (precision,waist drum shape and shape accuracy)were studied.So the limit value of working fluid conductivity in the finishing machining was determined,to en-sure the feasibility of the working fluid intelligence exchange on MSWEDM.%通过实验方法研究了工作液电导率对中走丝电火花线切割机床加工工艺性指标的影响。分析了工作液电导率对加工状态(加工电压、加工电流)的影响规律;分析了工作液电导率对切割速度、表面粗糙度和加工精度(尺寸精度、腰鼓形和形状精度)工艺性指标的影响规律,从而确定了精加工工作液电导率上限值,保证中走丝电火花线切割机床工作液智能交换控制的可行性。

  17. Evaluation of gowns and coveralls used by medical personnel working with Ebola patients against simulated bodily fluids using an Elbow Lean Test.

    Science.gov (United States)

    Jaques, Peter A; Gao, Pengfei; Kilinc-Balci, Selcen; Portnoff, Lee; Weible, Robyn; Horvatin, Matthew; Strauch, Amanda; Shaffer, Ronald

    2016-11-01

    Gowns and coveralls are important components of protective ensembles used during the management of known or suspected Ebola patients. In this study, an Elbow Lean Test was used to obtain a visual semi-quantitative measure of the resistance of medical protective garments to the penetration of two bodily fluid simulants. Tests were done on swatches of continuous and discontinuous regions of fabrics cut from five gowns and four coveralls at multiple elbow pressure levels (2-44 PSI). Swatches cut from the continuous regions of one gown and two coveralls did not have any strike-through. For discontinuous regions, only the same gown consistently resisted fluid strike-through. As hypothesized, with the exception of one garment, fluid strike-through increased with higher applied elbow pressure, was higher for lower fluid surface tension, and was higher for the discontinuous regions of the protective garments.

  18. Implementing Evidence-Based Practice Education in Social Work: A Transdisciplinary Approach

    Science.gov (United States)

    Bellamy, Jennifer L.; Mullen, Edward J.; Satterfield, Jason M.; Newhouse, Robin P.; Ferguson, Molly; Brownson, Ross C.; Spring, Bonnie

    2013-01-01

    Evidence based practice (EBP) is reflected in social work publications, accreditation standards, research, and funding opportunities. However, implementing EBP in social work practice and education has proven challenging, highlighting the need for additional resources. This paper describes the Transdisciplinary Model of EBP, a model based on…

  19. Florida's Work-Based Learning and Child Labor Law. Resource Guide.

    Science.gov (United States)

    Florida State Univ., Tallahassee. School-to-Work Clearinghouse.

    This guide was developed to address issues related to work-based learning experiences at an employer's worksite and to explain when and how federal and state (Florida) labor laws and minimum wage provisions apply. It includes the following documents: "Definitions of Terms--Work Based Learning" (Institute for Workforce Competitiveness);…

  20. Pedagogy of Work-Based Learning: The Role of the Learning Group

    Science.gov (United States)

    Siebert, Sabina; Mills, Vince; Tuff, Caroline

    2009-01-01

    Purpose: The aim of this paper is to evaluate the role of learning from participation in a group of work-based learners. Design/methodology/approach: This study relies on qualitative data obtained from a survey of perspectives of students on two work-based learning programmes. A group of 16 undergraduate and seven postgraduate students…