J. Ambrose, A. Hashemi, Julie Schneider, D. Stubbs, K. Aaron, M. Shao, T. Vanzandt
This paper describes analytical and experimental thermal results for a 33.5 cm diameter plano mirror under conditions of small thermal perturbations (steady-state temperature gradients of 10–100 mK). These tests are intended to support verification of specific thermal requirements for a space interferometer. The primary thermal requirement is knowledge/control of temporal changes in mirror gradients to the 1 mK (0.001 K) level. Tests were performed with small heat inputs to the back of the mirror, which was suspended in a thermally-uniform shroud. Correlation of thermal models for both conductively and radiatively-heated test configurations were performed, and results indicate very good agreement between the thermal model predictions and the temperature measurements. The modeling uncertainty based on the test correlation is estimated to be ±3 mK for absolute temporal comparisons. Comparisons for temporal change of gradient are shown to be within 1 mK for small perturbations. The paper describes the test setup, test results, model correlation and uncertainty estimates.
{"title":"Measurement and Prediction of Temperature Distributions in Optical Elements in the Millikelvin Regime","authors":"J. Ambrose, A. Hashemi, Julie Schneider, D. Stubbs, K. Aaron, M. Shao, T. Vanzandt","doi":"10.1115/imece2000-1569","DOIUrl":"https://doi.org/10.1115/imece2000-1569","url":null,"abstract":"\u0000 This paper describes analytical and experimental thermal results for a 33.5 cm diameter plano mirror under conditions of small thermal perturbations (steady-state temperature gradients of 10–100 mK). These tests are intended to support verification of specific thermal requirements for a space interferometer. The primary thermal requirement is knowledge/control of temporal changes in mirror gradients to the 1 mK (0.001 K) level. Tests were performed with small heat inputs to the back of the mirror, which was suspended in a thermally-uniform shroud. Correlation of thermal models for both conductively and radiatively-heated test configurations were performed, and results indicate very good agreement between the thermal model predictions and the temperature measurements. The modeling uncertainty based on the test correlation is estimated to be ±3 mK for absolute temporal comparisons. Comparisons for temporal change of gradient are shown to be within 1 mK for small perturbations. The paper describes the test setup, test results, model correlation and uncertainty estimates.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125445357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Convection, diffusion, and phase change processes influence heat and mass transfer through textile materials used in clothing systems. For example, water in a hygroscopic porous textile may exist in vapor or liquid form in the pore spaces or in bound form when it has been absorbed by the solid phase, which is typically some kind of hydrophilic polymer. Phase changes associated with water include liquid evaporation/condensation in the pore spaces and sorption/desorption from hydrophilic polymer fibers. Certain materials such as encapsulated paraffins may also be added to textiles; these materials are designed to undergo a solid-liquid phase change over temperature ranges near human body temperature, which influences the perceived comfort of clothing. Additional factors such as the swelling of the solid polymer due to water imbibition, and the heat of sorption evolved when the water is absorbed by the polymeric matrix, can all be incorporated into the appropriate conservation and transport equations describing heat and mass transfer through clothing layers. These physical factors, nonlinear material properties, and complex multiphase flows make the task of modeling and predicting levels of protection and comfort of various clothing designs difficult and elusive. Computational fluid dynamics (CFD) has proven to be useful at several levels of material and system modeling to evaluate and design protective clothing systems and material components. This paper summarizes current and past work aimed at utilizing CFD techniques for protective clothing applications.
{"title":"Application of Computational Fluid Dynamics to Protective Clothing System Evaluation","authors":"P. Gibson, M. Charmchi","doi":"10.1115/imece2000-1570","DOIUrl":"https://doi.org/10.1115/imece2000-1570","url":null,"abstract":"\u0000 Convection, diffusion, and phase change processes influence heat and mass transfer through textile materials used in clothing systems. For example, water in a hygroscopic porous textile may exist in vapor or liquid form in the pore spaces or in bound form when it has been absorbed by the solid phase, which is typically some kind of hydrophilic polymer. Phase changes associated with water include liquid evaporation/condensation in the pore spaces and sorption/desorption from hydrophilic polymer fibers. Certain materials such as encapsulated paraffins may also be added to textiles; these materials are designed to undergo a solid-liquid phase change over temperature ranges near human body temperature, which influences the perceived comfort of clothing. Additional factors such as the swelling of the solid polymer due to water imbibition, and the heat of sorption evolved when the water is absorbed by the polymeric matrix, can all be incorporated into the appropriate conservation and transport equations describing heat and mass transfer through clothing layers. These physical factors, nonlinear material properties, and complex multiphase flows make the task of modeling and predicting levels of protection and comfort of various clothing designs difficult and elusive. Computational fluid dynamics (CFD) has proven to be useful at several levels of material and system modeling to evaluate and design protective clothing systems and material components. This paper summarizes current and past work aimed at utilizing CFD techniques for protective clothing applications.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125496672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mathematical modeling of utility boilers is a difficult problem due to the multiplicity of physical phenomena involved and to the interaction between different phenomena. However, reliable models are extremely useful since they can be used to design new equipment, and to optimize and retrofit units in operation. In this paper a survey of the work carried out at Institute superior Técnico (IST) in Lisbon is reported. Only the work based on comprehensive models, i.e., those accounting for all the relevant physical phenomena taking place in the combustion chamber is addressed. The models employed are briefly outlined. Then, four examples of application are given, two of them for coal-fired boilers where the effect of low NOx burners and coal over coal reburning is investigated, and the other two for oil-fired boilers where parallelization of the code and simulation of the convection chamber are reported.
{"title":"The Mathematical Modeling of Utility Boilers at IST","authors":"P. Coelho, J. Azevedo, L. M. Coelho","doi":"10.1115/imece2000-1554","DOIUrl":"https://doi.org/10.1115/imece2000-1554","url":null,"abstract":"The mathematical modeling of utility boilers is a difficult problem due to the multiplicity of physical phenomena involved and to the interaction between different phenomena. However, reliable models are extremely useful since they can be used to design new equipment, and to optimize and retrofit units in operation. In this paper a survey of the work carried out at Institute superior Técnico (IST) in Lisbon is reported. Only the work based on comprehensive models, i.e., those accounting for all the relevant physical phenomena taking place in the combustion chamber is addressed. The models employed are briefly outlined. Then, four examples of application are given, two of them for coal-fired boilers where the effect of low NOx burners and coal over coal reburning is investigated, and the other two for oil-fired boilers where parallelization of the code and simulation of the convection chamber are reported.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"360 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122853961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An existing in-cylinder thermal regeneration concept for the Diesel engines is examined for the roles of the porous regenerator motion and the fuel injection strategies on the fuel evaporation and combustion and on the engine efficiency. While the heated air emanating from the regenerator enhances fuel evaporation resulting in a superadiabatic combustion (thus increasing thermal efficiency), the corresponding increase in the thermal NOx is undesirable. A multi-gas-zone and a single-step reaction model are used with a Lagrangian droplet tracking model that allows for filtration by the regenerator. A thermal efficiency of 52 percent is predicted, compared to 45 percent of the conventional Diesel engines. The optimal regenerative cooling stroke occurs close to the peak flame temperature, thus increasing the superadiabatic flame temperature and the peak pressure, while decreasing the expansion stroke pressure and the pressure drop through the regenerator. During the regenerative heating stroke, the heated air enhances the droplet evaporation, resulting in a more uniform, premixed combustion and a higher peak pressure, and thus a larger mechanical work.
{"title":"Evaporation-Combustion Affected by In-Cylinder, Reciprocating Porous Regenerator","authors":"Chanwoo Park, M. Kaviany","doi":"10.1115/1.1418368","DOIUrl":"https://doi.org/10.1115/1.1418368","url":null,"abstract":"\u0000 An existing in-cylinder thermal regeneration concept for the Diesel engines is examined for the roles of the porous regenerator motion and the fuel injection strategies on the fuel evaporation and combustion and on the engine efficiency. While the heated air emanating from the regenerator enhances fuel evaporation resulting in a superadiabatic combustion (thus increasing thermal efficiency), the corresponding increase in the thermal NOx is undesirable.\u0000 A multi-gas-zone and a single-step reaction model are used with a Lagrangian droplet tracking model that allows for filtration by the regenerator. A thermal efficiency of 52 percent is predicted, compared to 45 percent of the conventional Diesel engines. The optimal regenerative cooling stroke occurs close to the peak flame temperature, thus increasing the superadiabatic flame temperature and the peak pressure, while decreasing the expansion stroke pressure and the pressure drop through the regenerator. During the regenerative heating stroke, the heated air enhances the droplet evaporation, resulting in a more uniform, premixed combustion and a higher peak pressure, and thus a larger mechanical work.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128274957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Permafrost (permanently frozen ground) underlies approximately 25% of the world’s land surface. Construction of surface facilities in these regions presents unique engineering challenges due to the alteration of the thermal regime at the ground surface. Even moderate disturbance of the pre-existing ground surface energy balance can induce permafrost thawing with consequent settlement and damage to buildings, roadways, or other man-made infrastructure. The present work examines the thermal characteristics of embankments constructed of unconventional, highly porous materials. Using these materials, a passive cooling effect can be achieved due to the unstable density stratification and resulting natural convection that occur during winter months. The convection enhances transport of heat out of the embankment, thus cooling the lower portions of the embankment and underlying foundation soil and preserving the permafrost layer. Numerical results obtained with an unsteady two-dimensional finite element model are compared to experimental measurements taken in full-scale field installations for the cases of open and closed (impermeable) side-slope boundary conditions.
{"title":"Passive Cooling of Permafrost Foundation Soils Using Porous Embankment Structures","authors":"D. Goering","doi":"10.1115/imece2000-1566","DOIUrl":"https://doi.org/10.1115/imece2000-1566","url":null,"abstract":"\u0000 Permafrost (permanently frozen ground) underlies approximately 25% of the world’s land surface. Construction of surface facilities in these regions presents unique engineering challenges due to the alteration of the thermal regime at the ground surface. Even moderate disturbance of the pre-existing ground surface energy balance can induce permafrost thawing with consequent settlement and damage to buildings, roadways, or other man-made infrastructure.\u0000 The present work examines the thermal characteristics of embankments constructed of unconventional, highly porous materials. Using these materials, a passive cooling effect can be achieved due to the unstable density stratification and resulting natural convection that occur during winter months. The convection enhances transport of heat out of the embankment, thus cooling the lower portions of the embankment and underlying foundation soil and preserving the permafrost layer. Numerical results obtained with an unsteady two-dimensional finite element model are compared to experimental measurements taken in full-scale field installations for the cases of open and closed (impermeable) side-slope boundary conditions.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124176763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, calculations of mixed-mode heat transfer in beds of randomly-packed cylinders are presented. An unstructured finite volume method is employed. Random packing is addressed by meshing a periodic module, and creating the bed by stacking and random lateral translation of modules. The ability of the finite volume scheme to employ arbitrary polyhedra is exploited in addressing the resulting non-conformal interfaces. Conduction and radiation are considered, but convection is ignored. Results are presented for conducting and semi-transparent cylinders for a range of fluid and solid conductivities and solid refractive indices and establish the viability and versatility of the method.
{"title":"Multi-Mode Heat Transfer in a Randomly Packed Bed of Cylindrical Rods Using a Finite Volume Scheme","authors":"J. Murthy, S. Mathur","doi":"10.1115/imece2000-1573","DOIUrl":"https://doi.org/10.1115/imece2000-1573","url":null,"abstract":"\u0000 In this paper, calculations of mixed-mode heat transfer in beds of randomly-packed cylinders are presented. An unstructured finite volume method is employed. Random packing is addressed by meshing a periodic module, and creating the bed by stacking and random lateral translation of modules. The ability of the finite volume scheme to employ arbitrary polyhedra is exploited in addressing the resulting non-conformal interfaces. Conduction and radiation are considered, but convection is ignored. Results are presented for conducting and semi-transparent cylinders for a range of fluid and solid conductivities and solid refractive indices and establish the viability and versatility of the method.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132474565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The quenching process is an important heat treatment method used to improve material properties. However, the heat transfer during quenching is particularly difficult to analyze and predict. To collect temperature data, quench probes have been used in controlled quenching experiments. The process of determination of the heat flux at the surface from the measured temperature data is the Inverse Heat Conduction Problem (IHCP), which is extremely sensitive to measurement errors. This paper reports on an experimental and theoretical study of quenching which is carried out to determine the surface heat flux history during a quenching process by an IHCP algorithm. The inverse heat conduction algorithm is applied to experimental data from a quenching experiment. The surface heat flux is then calculated, and the theoretical curve is compared with experimental results.
{"title":"Inverse Heat Flux Problem in Quenching","authors":"M. K. Alam, Rex J. Kuriger, R. Zhong","doi":"10.1115/imece2000-1585","DOIUrl":"https://doi.org/10.1115/imece2000-1585","url":null,"abstract":"\u0000 The quenching process is an important heat treatment method used to improve material properties. However, the heat transfer during quenching is particularly difficult to analyze and predict. To collect temperature data, quench probes have been used in controlled quenching experiments. The process of determination of the heat flux at the surface from the measured temperature data is the Inverse Heat Conduction Problem (IHCP), which is extremely sensitive to measurement errors. This paper reports on an experimental and theoretical study of quenching which is carried out to determine the surface heat flux history during a quenching process by an IHCP algorithm. The inverse heat conduction algorithm is applied to experimental data from a quenching experiment. The surface heat flux is then calculated, and the theoretical curve is compared with experimental results.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115719741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Turbulent flow in a channel, totally and partially filled with a porous medium, is simulated with a proposed turbulence model. Two cases are analyzed, namely clear flow past a porous obstacle and flow through a porous medium having a cavity with a higher porosity. Mean and turbulence quantities were solved within both computational domains using a single numerical technique. The control volume approach was used to discretize the governing equations. In the first case analyzed, the flow penetration into the porous substrate is accompanied by generation of turbulence kinetic energy within the obstacle. In the second geometry, the flow is pushed towards the cavity as porosity increases.
{"title":"Simulation of Turbulent Flow Through Hybrid Porous Medium: Clear Fluid Domains","authors":"M. D. de Lemos, Marcos H. J. Pedras","doi":"10.1115/imece2000-1567","DOIUrl":"https://doi.org/10.1115/imece2000-1567","url":null,"abstract":"\u0000 Turbulent flow in a channel, totally and partially filled with a porous medium, is simulated with a proposed turbulence model. Two cases are analyzed, namely clear flow past a porous obstacle and flow through a porous medium having a cavity with a higher porosity. Mean and turbulence quantities were solved within both computational domains using a single numerical technique. The control volume approach was used to discretize the governing equations. In the first case analyzed, the flow penetration into the porous substrate is accompanied by generation of turbulence kinetic energy within the obstacle. In the second geometry, the flow is pushed towards the cavity as porosity increases.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115029447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Improvements in the modeling of high-speed reacting propulsion flowfields are sought through the coupling of a stiff integrator to determine chemical reaction rates with a multidimensional CFD code. Detailed chemical kinetics models usually have significantly shorter reaction time scales than the fluid time scales, resulting in stiff governing equations and robustness issues. The present work investigates the application of a stiff ordinary differential equation solver, coupled to a diagonalized alternating-direction implicit scheme to decouple the governing time scales. This coupled ODE-ADI split-operator technique is applied to two high-speed reacting flows using hydrogen/air chemistry. The results from the stiff integrator method are compared to the traditional coupled approach utilizing 8- and 18-step kinetics models. Time-step choice, robustness, and comparison of results between the different solution methods are discussed, along with CPU times.
{"title":"Investigation of a Stiff-Integrator Scheme for High-Speed Reacting Flows","authors":"Lance D. Woolley, D. Schwer, R. Daines","doi":"10.1115/imece2000-1563","DOIUrl":"https://doi.org/10.1115/imece2000-1563","url":null,"abstract":"\u0000 Improvements in the modeling of high-speed reacting propulsion flowfields are sought through the coupling of a stiff integrator to determine chemical reaction rates with a multidimensional CFD code. Detailed chemical kinetics models usually have significantly shorter reaction time scales than the fluid time scales, resulting in stiff governing equations and robustness issues. The present work investigates the application of a stiff ordinary differential equation solver, coupled to a diagonalized alternating-direction implicit scheme to decouple the governing time scales. This coupled ODE-ADI split-operator technique is applied to two high-speed reacting flows using hydrogen/air chemistry. The results from the stiff integrator method are compared to the traditional coupled approach utilizing 8- and 18-step kinetics models. Time-step choice, robustness, and comparison of results between the different solution methods are discussed, along with CPU times.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128138314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thin, plate-like structures are often encountered in industrial heat transfer applications. Discretizing them as volumetric elements along with the rest of the domain results in a large number of elements and significantly increases the cost of computational analysis of such problems. It can also cause numerical errors and convergence difficulties because of the large aspect ratios and skewness of the mesh. On the other hand, treating the conduction in such regions separately is also unattractive because the inherent coupling of the two problems makes for very slow convergence. In this paper we present an alternative approach which treats such structures as planar elements while still maintaining full coupling between the temperature fields in the two regions. Consequently the solution for the entire domain can be obtained simultaneously without significant increase in problem complexity. The method is validated using canonical problems as well as solutions obtained by full discretization of the thin structures. Compared to the latter, the present approach is found to be significantly more efficient and robust.
{"title":"Development of Finite Volume Shell Conduction Model for Complex Geometries","authors":"S. Mathur, C. K. Lim, R. Nair","doi":"10.1115/imece2000-1577","DOIUrl":"https://doi.org/10.1115/imece2000-1577","url":null,"abstract":"\u0000 Thin, plate-like structures are often encountered in industrial heat transfer applications. Discretizing them as volumetric elements along with the rest of the domain results in a large number of elements and significantly increases the cost of computational analysis of such problems. It can also cause numerical errors and convergence difficulties because of the large aspect ratios and skewness of the mesh. On the other hand, treating the conduction in such regions separately is also unattractive because the inherent coupling of the two problems makes for very slow convergence. In this paper we present an alternative approach which treats such structures as planar elements while still maintaining full coupling between the temperature fields in the two regions. Consequently the solution for the entire domain can be obtained simultaneously without significant increase in problem complexity. The method is validated using canonical problems as well as solutions obtained by full discretization of the thin structures. Compared to the latter, the present approach is found to be significantly more efficient and robust.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"157 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132735525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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