A universal dimensionless number, ΠN∼NN1+Pr-1 ,Pr being the usual Prandtl number and NN the limit of ΠN for Pr → ∞, is introduced for all natural convection processes. For NN=Ra ,Ra being the usual Rayleigh number, ΠN describes buoyancy-driven natural convection. For NN=Ma ,Ma being the usual Marangoni number, ΠN describes thermocapillary-driven natural convection. For NN=TaPr ,Ta being the usual Taylor number, ΠN describes centrifugally-driven natural convection. In terms of ΠN, a thermal Kolmogorov scale relative to an integral scale, ηθℓ∼ΠN-1/3 is introduced for natural convection including buoyancy, thermocapillary and centrifugally-driven flows. Heat transfer associated with these flows is modeled byNu∼ΠN1/3 ,Nu being the usual Nusselt number. A variety of turbulent natural convection phenomena are shown correlating the model.
一个通用的无量纲数ΠN ~ NN1+Pr-1,Pr是通常的普朗特数，NN是Pr→∞的极限ΠN，被引入到所有自然对流过程中。对于NN=Ra,Ra为通常的瑞利数，ΠN描述浮力驱动的自然对流。对于NN=Ma,Ma是通常的Marangoni数，ΠN描述了热毛细管驱动的自然对流。对于NN=TaPr,Ta为通常的泰勒数，ΠN描述离心驱动的自然对流。根据ΠN，相对于积分尺度的热Kolmogorov尺度，ηθ r ~ ΠN-1/3引入了自然对流，包括浮力、热毛细和离心驱动的流动。与这些流动相关的传热用Nu ~ ΠN1/3来模拟，Nu是通常的努塞尔数。与该模型相关的各种湍流自然对流现象也被展示出来。
{"title":"Microscales of Natural Convection","authors":"V. Arpaci","doi":"10.1115/imece1997-0888","DOIUrl":"https://doi.org/10.1115/imece1997-0888","url":null,"abstract":"\u0000 A universal dimensionless number, ΠN∼NN1+Pr-1 ,Pr being the usual Prandtl number and NN the limit of ΠN for Pr → ∞, is introduced for all natural convection processes. For NN=Ra ,Ra being the usual Rayleigh number, ΠN describes buoyancy-driven natural convection. For NN=Ma ,Ma being the usual Marangoni number, ΠN describes thermocapillary-driven natural convection. For NN=TaPr ,Ta being the usual Taylor number, ΠN describes centrifugally-driven natural convection.\u0000 In terms of ΠN, a thermal Kolmogorov scale relative to an integral scale, ηθℓ∼ΠN-1/3 is introduced for natural convection including buoyancy, thermocapillary and centrifugally-driven flows. Heat transfer associated with these flows is modeled byNu∼ΠN1/3 ,Nu being the usual Nusselt number. A variety of turbulent natural convection phenomena are shown correlating the model.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132414192","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}
Mean heat transfer and flow characteristics of a two-dimensional air jet impinging on a uniform heat flux surface were investigated. Measurements were made in a steady unforced jet, and in a jet with externally introduced forcing. The jet issued from a 24:1 aspect ratio rectangular nozzle. The heat transfer characteristics are parameterized by jet Reynolds number based on the hydraulic diameter and on the nozzle-to-plate spacing. Flow conditions (mean, turbulent fluctuations and power spectra) exiting the jet were measured and used to interpret their influences on the stagnation point heat transfer. A comparison of an unforced impinging jet to a forced impinging jet showed enhancements in the heat transfer rate of up to 57% with forcing.
{"title":"Turbulent Heat Transfer in a Forced and Unforced Two Dimensional Air Jet Impinging on an Isoflux Surface","authors":"Edmund Singer, A. Ortega","doi":"10.1115/imece1997-0894","DOIUrl":"https://doi.org/10.1115/imece1997-0894","url":null,"abstract":"\u0000 Mean heat transfer and flow characteristics of a two-dimensional air jet impinging on a uniform heat flux surface were investigated. Measurements were made in a steady unforced jet, and in a jet with externally introduced forcing. The jet issued from a 24:1 aspect ratio rectangular nozzle. The heat transfer characteristics are parameterized by jet Reynolds number based on the hydraulic diameter and on the nozzle-to-plate spacing. Flow conditions (mean, turbulent fluctuations and power spectra) exiting the jet were measured and used to interpret their influences on the stagnation point heat transfer. A comparison of an unforced impinging jet to a forced impinging jet showed enhancements in the heat transfer rate of up to 57% with forcing.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132438000","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}
Measurements of fully-developed augmented convection and pressure drop of air flow in an isothermal, symmetrically grooved channel are reported for channel Reynolds numbers ranging from 800 to 5,000. Grooves, oriented transverse to the flow, are of triangular shape with dimensions that are comparable to the hydraulic diameter of the channel. The grooved section is designed to excite instabilities in the flow leading to increased mixing at sub-transitional Reynolds numbers. Local heat transfer measurements are made using a holographic interferometer. Interferograms, representative of the cross-span-average temperature of the air in the channel, are analyzed to produce data records of the air temperature distribution and the local heat flux along the grooved walls. Heat flux distributions are spatially averaged to produce a correlation of fully-developed Colburn j-factor for this surface configuration. A performance evaluation of the grooved surface applied to a simple heat exchanger shows that it provides thermal performance which is comparable to other surfaces commonly employed in compact heat exchangers.
{"title":"Measurements of Fully-Developed Augmented Convection in a Symmetrically Grooved Channel","authors":"R. Wirtz, Feng Huang, M. Greiner","doi":"10.1115/imece1997-0891","DOIUrl":"https://doi.org/10.1115/imece1997-0891","url":null,"abstract":"\u0000 Measurements of fully-developed augmented convection and pressure drop of air flow in an isothermal, symmetrically grooved channel are reported for channel Reynolds numbers ranging from 800 to 5,000. Grooves, oriented transverse to the flow, are of triangular shape with dimensions that are comparable to the hydraulic diameter of the channel. The grooved section is designed to excite instabilities in the flow leading to increased mixing at sub-transitional Reynolds numbers.\u0000 Local heat transfer measurements are made using a holographic interferometer. Interferograms, representative of the cross-span-average temperature of the air in the channel, are analyzed to produce data records of the air temperature distribution and the local heat flux along the grooved walls. Heat flux distributions are spatially averaged to produce a correlation of fully-developed Colburn j-factor for this surface configuration. A performance evaluation of the grooved surface applied to a simple heat exchanger shows that it provides thermal performance which is comparable to other surfaces commonly employed in compact heat exchangers.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126422672","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}
Flow and combustion models are being used to evaluate new designs and retrofit options for various industrial combustion systems. Combustion models being used today are often very modular and, since they apply serial algorithms, require long run times to produce results. It is common for solutions to take several days, and the use of finite rate chemistry and Lagrangian based particle models can lengthen run times to a week or more. The modularity of these methods makes them candidates for parallel computing. This paper presents results for a distributed computing algorithm using the PVM software, which is applied to the finite rate chemistry and particle transport modules. It is based on a master-slave algorithm in which the master doles work to a number of independent processors. A load balancing scheme is used to account for the variability in the time the slaves complete their work. PVM was successfully used for parallel computations in the finite rate chemistry and particle modules. Significant speedups were found for both modules, but the work clearly indicates the need to control granularity and the need to optimize the algorithm specifically for the processors being used. Future work is planned to improve the algorithms presented here as well as extending the work to other parts of the combustion model.
{"title":"Parallel Computing Strategies for a Disperse Phase Flow and Combustion Model","authors":"W. Fiveland, K. L. Parker, R. Gansman","doi":"10.1115/imece1997-0927","DOIUrl":"https://doi.org/10.1115/imece1997-0927","url":null,"abstract":"\u0000 Flow and combustion models are being used to evaluate new designs and retrofit options for various industrial combustion systems. Combustion models being used today are often very modular and, since they apply serial algorithms, require long run times to produce results. It is common for solutions to take several days, and the use of finite rate chemistry and Lagrangian based particle models can lengthen run times to a week or more. The modularity of these methods makes them candidates for parallel computing.\u0000 This paper presents results for a distributed computing algorithm using the PVM software, which is applied to the finite rate chemistry and particle transport modules. It is based on a master-slave algorithm in which the master doles work to a number of independent processors. A load balancing scheme is used to account for the variability in the time the slaves complete their work.\u0000 PVM was successfully used for parallel computations in the finite rate chemistry and particle modules. Significant speedups were found for both modules, but the work clearly indicates the need to control granularity and the need to optimize the algorithm specifically for the processors being used. Future work is planned to improve the algorithms presented here as well as extending the work to other parts of the combustion model.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122277383","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}
Experiments were conducted to investigate natural convection heat transfer from single enclosed helical coils in a vertical orientation. Coils having different diameter, pitch, and tube diameters were placed inside a cylindrical shell of fixed height and diameter, to form a natural convection shell-and-coil heat exchanger. Effects of tube diameter, coil surface area and coil pitch on heat transfer coefficient were studied. Nu-Ra correlations were presented based on different characteristic lengths. The data was correlated well by NuDhx = 0.002RaDhx0.630 using heat exchanger hydraulic diameter as the characteristic length.
{"title":"Natural Convection From Vertical Helical Coils in a Cylindrical Enclosure","authors":"H. Taherian, Peter L. Allen","doi":"10.1115/imece1997-0902","DOIUrl":"https://doi.org/10.1115/imece1997-0902","url":null,"abstract":"\u0000 Experiments were conducted to investigate natural convection heat transfer from single enclosed helical coils in a vertical orientation. Coils having different diameter, pitch, and tube diameters were placed inside a cylindrical shell of fixed height and diameter, to form a natural convection shell-and-coil heat exchanger. Effects of tube diameter, coil surface area and coil pitch on heat transfer coefficient were studied. Nu-Ra correlations were presented based on different characteristic lengths. The data was correlated well by NuDhx = 0.002RaDhx0.630 using heat exchanger hydraulic diameter as the characteristic length.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114746295","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}
J. Baughn, M. R. Anderson, J. E. Mayhew, Robert J. Butler
A new periodic transient method for the measurement of local heat transfer coefficients is described. In this method, the freestream temperature is periodically heated while the local surface temperature fluctuation is measured. The local heat transfer coefficient can be determined from the frequency, the ratio of the surface temperature fluctuation to the free stream temperature fluctuation and the wall thermal properties. Measurements on a Plexiglas flat plate with a laminar boundary layer are presented as a demonstration of this method. For this demonstration the free stream is electrically heated using a fine wire cloth. The surface temperature fluctuation is measured using liquid crystals with a hue analysis technique. The results show that this is a viable method for measuring local heat transfer coefficients. Its advantages are that it approximates a uniform temperature thermal boundary condition and it is not necessary to control or measure the initial wall temperature.
{"title":"A Periodic Transient Method Using Liquid Crystals for the Measurement of Local Heat Transfer Coefficients","authors":"J. Baughn, M. R. Anderson, J. E. Mayhew, Robert J. Butler","doi":"10.1115/imece1997-0896","DOIUrl":"https://doi.org/10.1115/imece1997-0896","url":null,"abstract":"\u0000 A new periodic transient method for the measurement of local heat transfer coefficients is described. In this method, the freestream temperature is periodically heated while the local surface temperature fluctuation is measured. The local heat transfer coefficient can be determined from the frequency, the ratio of the surface temperature fluctuation to the free stream temperature fluctuation and the wall thermal properties. Measurements on a Plexiglas flat plate with a laminar boundary layer are presented as a demonstration of this method. For this demonstration the free stream is electrically heated using a fine wire cloth. The surface temperature fluctuation is measured using liquid crystals with a hue analysis technique. The results show that this is a viable method for measuring local heat transfer coefficients. Its advantages are that it approximates a uniform temperature thermal boundary condition and it is not necessary to control or measure the initial wall temperature.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121780256","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 overview is given of analytical algorithms for estimating the optical properties of a homogeneous slab or a homogeneous optically-thin, convex-shaped medium.
概述了用于估计均匀平板或均匀光学薄的凸形介质光学性质的解析算法。
{"title":"Analytical Solutions for Inverse Radiative Transfer Optical Property Estimation","authors":"N. Mccormick","doi":"10.1115/imece1997-0929","DOIUrl":"https://doi.org/10.1115/imece1997-0929","url":null,"abstract":"\u0000 An overview is given of analytical algorithms for estimating the optical properties of a homogeneous slab or a homogeneous optically-thin, convex-shaped medium.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125135781","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 wall heat transfer enhancement behind a circular cylinder-wall junction was investigated experimentally for Reynolds numbers ranging from ReD = 21,000 to 54,000 for locations up to 12 diameters downstream of the cylinder leading edge. Surface heat transfer was studied using a fully-heated surface downstream of the cylinder to provide traditional heat transfer coefficients, and thin-film surface sensors flush-mounted on an unheated surface to provide adiabatic heat transfer coefficients. Flow field transport measurements were obtained with a triple-wire Reynolds heat flux probe. The enhancement could be attributed to two effects: (1) a local fluid dynamic effect attributed to increased eddy diffusivity and subsequent increased turbulent transport and (2) an upstream heating effect, caused by reduced wall temperatures in the region directly behind the obstacle, and their effect on the subsequent redevelopment of the boundary layer downstream. The adiabatic heat transfer coefficients obtained from the surface sensors provided misleading results, because of the breakdown in the analogy between heat and momentum transport.
{"title":"Mechanisms of Heat Transfer Enhancement in a Turbulent Boundary Layer Downstream of a Cylinder-Wall Junction","authors":"D. Wroblewski, Q. Xie","doi":"10.1115/imece1997-0890","DOIUrl":"https://doi.org/10.1115/imece1997-0890","url":null,"abstract":"\u0000 The wall heat transfer enhancement behind a circular cylinder-wall junction was investigated experimentally for Reynolds numbers ranging from ReD = 21,000 to 54,000 for locations up to 12 diameters downstream of the cylinder leading edge. Surface heat transfer was studied using a fully-heated surface downstream of the cylinder to provide traditional heat transfer coefficients, and thin-film surface sensors flush-mounted on an unheated surface to provide adiabatic heat transfer coefficients. Flow field transport measurements were obtained with a triple-wire Reynolds heat flux probe. The enhancement could be attributed to two effects: (1) a local fluid dynamic effect attributed to increased eddy diffusivity and subsequent increased turbulent transport and (2) an upstream heating effect, caused by reduced wall temperatures in the region directly behind the obstacle, and their effect on the subsequent redevelopment of the boundary layer downstream. The adiabatic heat transfer coefficients obtained from the surface sensors provided misleading results, because of the breakdown in the analogy between heat and momentum transport.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"13 34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129226681","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 analytical method is discussed for predicting temperature in a material layer with embedded cooling channels to control material temperature. Problems of this type are encountered in the aerospace industry and include high-temperature or high-heat-flux protection for advanced composite-material skins of high-speed air vehicles, thermal laminar flow control on supersonic civil transports, or infrared signal suppression on military vehicles. A Green’s function solution of the diffusion equation is used to simultaneously predict the localized and global effects of temperature in the material and embedded cooling channels. The integral method is used to calculate temperature in the cooling fluid and material simultaneously. This method of calculation preserves the three-dimensional nature of this problem.
{"title":"Closed-Form Solution of Temperature and Heat Flux in Embedded Cooling Channels","authors":"S. C. Griggs, A. Haji-sheikh","doi":"10.1115/imece1997-0917","DOIUrl":"https://doi.org/10.1115/imece1997-0917","url":null,"abstract":"\u0000 An analytical method is discussed for predicting temperature in a material layer with embedded cooling channels to control material temperature. Problems of this type are encountered in the aerospace industry and include high-temperature or high-heat-flux protection for advanced composite-material skins of high-speed air vehicles, thermal laminar flow control on supersonic civil transports, or infrared signal suppression on military vehicles. A Green’s function solution of the diffusion equation is used to simultaneously predict the localized and global effects of temperature in the material and embedded cooling channels. The integral method is used to calculate temperature in the cooling fluid and material simultaneously. This method of calculation preserves the three-dimensional nature of this problem.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128270795","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}
R. Roy, V. Agarwal, S. Devasenathipathy, Junru He, Lars Meier, Yong W. Kim, Jeff Howe, Ko-Sun Ho
Experiments and computations are being carried out with the objective of understanding the turbulent flow field and convective heat transfer in gas turbine disk cavities. An experimental rig which features a configuration of rotor and stator disks simpler than in actual gas turbines but retains the important features of stator vanes, rotor blades, and realistic rim seals on the disks has been constructed for the experiments. The commercial CFD code FLUENT/UNS is used for the computations. We report measurements, in experiments with mainstream and secondary air flows, of the convective heat transfer coefficient and cooling effectiveness distributions on the rotor disk surface. Also reported are the radial distribution of the time-mean static pressure at the stator disk and the circumferential distribution of the same in the mainstream gas passage. Implications of the cooling effectiveness and static pressure distributions vis-á-vis the ingestion of mainstream gas into the disk cavity are discussed briefly. Computational results are presented and compared with measurements in some cases.
{"title":"A Study of the Flow Field and Convective Heat Transfer in a Model Rotor-Stator Cavity","authors":"R. Roy, V. Agarwal, S. Devasenathipathy, Junru He, Lars Meier, Yong W. Kim, Jeff Howe, Ko-Sun Ho","doi":"10.1115/imece1997-0898","DOIUrl":"https://doi.org/10.1115/imece1997-0898","url":null,"abstract":"\u0000 Experiments and computations are being carried out with the objective of understanding the turbulent flow field and convective heat transfer in gas turbine disk cavities. An experimental rig which features a configuration of rotor and stator disks simpler than in actual gas turbines but retains the important features of stator vanes, rotor blades, and realistic rim seals on the disks has been constructed for the experiments. The commercial CFD code FLUENT/UNS is used for the computations.\u0000 We report measurements, in experiments with mainstream and secondary air flows, of the convective heat transfer coefficient and cooling effectiveness distributions on the rotor disk surface. Also reported are the radial distribution of the time-mean static pressure at the stator disk and the circumferential distribution of the same in the mainstream gas passage. Implications of the cooling effectiveness and static pressure distributions vis-á-vis the ingestion of mainstream gas into the disk cavity are discussed briefly. Computational results are presented and compared with measurements in some cases.","PeriodicalId":306962,"journal":{"name":"Heat Transfer: Volume 3","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125737321","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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