Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems最新文献

{"title":"A Numerical Study on Reducing the Stator Blade Surface Temperature in the Ultra-High Efficiency Gas Turbine Engine by Indexing Fuel Injectors and Using Film Cooling","authors":"S. Ghoreyshi, M. Schobeiri","doi":"10.1115/GT2018-75967","DOIUrl":"https://doi.org/10.1115/GT2018-75967","url":null,"abstract":"The Ultra-High Efficiency Gas Turbine technology, UHEGT, has been introduced in our previous publications [1]-[4]. In UHEGT, the combustion process is no longer contained in isolation between the compressor and turbine, rather distributed and integrated within the axial gaps before each stator row. As shown in the previous publications, this technology substantially increases the thermal efficiency of the engine to 45% and above. Since the combustion process is brought into the turbine stages in UHEGT, the stator blades are exposed to high temperature gases and are prone to be overheated. To address this issue, two different approaches are investigated in this paper in order to control and reduce the temperature on the stator blade surface. The first approach is indexing (clocking) of the fuel injectors (cylindrical tubes extended from hub to shroud), in which the positions of the injectors are adjusted relative to each other and the stator blades. The second approach is using film cooling, in which cooling holes are added on the blade surface to bring down the temperature via coolant injection. Four configurations are designed and studied via computational fluid dynamics (CFD) to evaluate the effectiveness of the two approaches. The objective functions in this evaluation are stator blade surface temperature, temperature non-uniformity at rotor inlet, total pressure loss over the injectors, and total power production by rotor. The results show that the second configuration, which uses the indexing approach, presents the most promising case in controlling the stator blade surface temperature. This configuration produces the lowest temperature distribution over the stator blade surface and the least amount of total pressure loss.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"4324 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115762414","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}

{"title":"Numerical Analysis of Heat Transfer Characteristics of Hexamethyldisiloxane (MM) at Supercritical Pressures","authors":"J. Fu, Guoqiang Xu, Yongkai Quan, Yanchen Fu, Bensi Dong","doi":"10.1115/GT2018-76260","DOIUrl":"https://doi.org/10.1115/GT2018-76260","url":null,"abstract":"Organic Rankine cycle (ORC) is one of the most promising solutions to utilize low-grade thermal energy for the worldwide energy crisis, environment deterioration, and climate change. Organic fluids, commonly with relatively low critical temperature and pressure, can be heated and compressed directly to the supercritical state in order to obtain better match with the heat source temperature and lower corresponding exergy destruction. Supercritical ORC has therefore attracted increasing attention in recent years. Supercritical fluids in the heated channels experience sharp changes in thermal properties during the pseudo-critical temperature range, leading to abnormal supercritical heat transfer characteristics. However, to the best of our knowledge, as one of the most challenging aspects related to the ORC modeling, heat transfer mechanisms for supercritical organic fluids have not been completely explained. To fill this gap, this work numerically analyzes the heat transfer to supercritical hexamethyldisiloxane (MM) with characteristics of high thermal stability and low critical parameters and therefore it is applicable for high temperature supercritical ORC system. In the numerical analysis, the shear stress transport k–ω turbulence model is employed to simulate the supercritical heat transfer process in a vertical upward tube under different boundary conditions of pressure, mass flux, and heat flux. Further insight is provided about the physical mechanisms of heat transfer deterioration with numerical results. The results show that the distributions of specific heat and turbulent kinetic energy are the key factors in determining the deterioration degree of heat transfer.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116915113","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}

{"title":"An Introduction Into the Clearance Management of Ansaldo GT36 From Development to Validation","authors":"S. Boeller, B. Feuillard, G. Filkorn, S. Olmes, F. Prou, C. Robson, R. Santos","doi":"10.1115/GT2018-75652","DOIUrl":"https://doi.org/10.1115/GT2018-75652","url":null,"abstract":"The optimization and evaluation of blading clearance is important for gas turbine efficiency and performance. The Ansaldo GT36 gas turbine offers high efficiency together with outstanding flexibility across a large load range. Active management of engine clearances during the complete development process followed by a thorough validation on the Ansaldo test plant facility in Birr, Switzerland enables the GT to attain ambitious clearance targets. The clearance at baseload must be minimized but is limited by the pinch point clearance during cold, warm and hot start-ups — including normal and fast ramp-up and/or shutdown. Therefore transient analysis is necessary for covering the different operating conditions. A well-established process of 2d finite element modelling of the whole engine model (WEM) comprised of axis-symmetric and plane stress elements was used during the design process from concept to detailed design to optimize the clearances. It delivers the transient stator and rotor deformation and together with the compressor and turbine airfoil deformation based on 3D models the basic clearance evaluation process is defined. The GT engine design was significantly influenced, starting with a simplified version of the WEM for identification of the most promising variants. Subsequently a detailed WEM was developed which is fully validated against measurements on the test engine. Different 3D effects are considered separately at identified critical transient conditions and overlaid on the 2d clearances which lead to the final optimized clearances. In addition to this, limitations from each step of the manufacturing process were identified and improved to reduce tolerances and uncertainties to their minimum. The results of the calculation and clearance prediction process are compared against clearance measurements during all kinds of GT operation and cooldown. Passive clearance indicators showing the remaining gap till rubbing would occur and rub marks, in areas that tolerate it, further validate the clearances and clearance prediction process.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129718287","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}

{"title":"Model Based Diagnostics of AE-T100 Micro Humid Air Turbine Cycle","authors":"M. Mahmood, Alessio Martini, A. Massardo, W. D. Paepe","doi":"10.1115/GT2018-75979","DOIUrl":"https://doi.org/10.1115/GT2018-75979","url":null,"abstract":"Micro gas turbines (mGT) are emerging power sources for distributed generation facilities with promising features like environment friendliness, high fuel flexibility, cost effectiveness and efficient cogeneration of heat and power (CHP). However, curtailed heat demand during summers reduces the plant operating hours per year and negatively affects the overall economic feasibility of a CHP project. The micro Humid Air Turbine (mHAT) cycle is one of the novel cycles to increase the electrical efficiency of the gas turbine by utilizing the exhaust gas heat in periods of low heat demand, thus avoiding the system shutdown. However, the water injection system can introduce additional pressure losses in the mGT cycle, which may lead to compressor surge and it may also affect the recuperator performance in the long run due to corrosion. Hence, numerical simulation and diagnostic tools are essential for cycle optimization of mHAT and prediction of performance degradation.\u0000 This work is focused on the real time application of the AE-T100 model for the mHAT system located at the Vrije Universiteit Brussel (VUB), which is based on the T100 mGT equipped with a spray saturation tower. The AE-T100 model is a steady-state simulation tool for mGT cycles, which has been developed within a collaboration between the University of Genova (Unige) and Ansaldo Energia, and has been successfully applied at the Ansaldo Enegia test rig (AE-T100) for the diagnostic purpose. For this study, the basic AE-T100 model has been modified to simulate the humidified cycle according to the VUB plant configuration. The modified AE-T100 model has been validated against the experimental data obtained from the mHAT unit at nominal and part load.\u0000 Once the model was validated using real operating conditions, it has been used for monitoring the recuperator performance over large number of tests in dry mode, conducted over the past five years, as well as initial tests in wet mode, from the VUB-mHAT system. This work has proved the modeling capability of the AE-T100 tool to simulate the mHAT cycle with reasonable accuracy and first diagnostic application of the AE-T100 tool, in dry mode. However, the lack of data available at present in wet mode does not allow to provide a complete and robust diagnostics of this novel cycle under wet operation.\u0000 Hence, this preliminary analysis will provide basis for more detail diagnostics of the mHAT cycle using AE-T100 tool, over a longer time period under wet operation, in future.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124640072","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}

{"title":"Optimization Analysis of Combined Heat and Power Plant of Multistage Gas Turbine for Marine Applications","authors":"Zhitao Wang, H. Lei, Yi-Guang Li, Shuying Li, Wang Weitian","doi":"10.1115/GT2018-76025","DOIUrl":"https://doi.org/10.1115/GT2018-76025","url":null,"abstract":"Nowadays, the rising demand for energy and serious environmental pollution become the motive to improve the energy structure, saving energy and optimize energy utilization. Based on a gas turbine, a marine multistage gas turbine combined heat and power (CHP) structure is proposed. The CHP system includes the top gas turbine Brayton cycle, the intermediate water Rankine cycle (WRC) and the bottom organic Rankine cycle (ORC). According to the method of screening organic Rankine cycle refrigerant to select the appropriate organic working fluids, and their physical characteristics are described. Based on the modular modelling method, the 3-stage CHP system is established. In order to more effectively absorb low temperature waste heat, three different kinds of 3-stage CHP structures were designed to recover the heat in the exhaust gas from the heat recover steam generator (HRSG). The thermodynamic model of the combined heat and power system of marine multistage gas turbine was used to simulate the performance of three different types of 3-stage CHP structures, the optimal 3-stage CHP structure was selected by comparing and analyzing the simulation results. Based on the simulation results of the design point, it is found that the introduction of the optimal 3-stage CHP structure can increase the power output by about 8.5% and improve the cycle thermal efficiency by about 4.32% compared with a conventional 2-stage CHP cycle where only gas turbine topping cycle and water Rankine bottoming cycle are included.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125627388","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}

{"title":"The Heron Fan: Concept Description and Preliminary Aerothermodynamic Analysis","authors":"F. Schöning, D. Kožulović","doi":"10.1115/GT2018-76529","DOIUrl":"https://doi.org/10.1115/GT2018-76529","url":null,"abstract":"The Heron Fan is a new concept of a fuel powered jet engine that does not utilize a conventional core engine. The fan, a single axial compressor of high diameter, creates thrust, similar to a turbofan. Its blades are hollow with inner channels to transport the core air from the hub to the tip, inducing radial compression. The combustion chamber is located in the casing region, either integrated in the blades or in an external ring. After burning, the core air is returned to the blades and is blown out through an expansion device with a large component in circumferential direction. This propels the fan in the opposite direction. The expansion device may be realized by nozzles integrated in the blade trailing edge or by turbine stages integrated in the blade tip region. Subsequently, the core air mixes with the bypass air, which passes the fan axially, and ejects through the main nozzle, producing thrust. To achieve higher compression ratios, it is possible to install core air compressor stages ahead of the fan.\u0000 The main purpose of this concept is to reduce weight and complexity of the engine, leading to lower production and operating costs. This is achieved by simplifying the engine architecture, integrating the functions and shortening some of the components. In particular, the core engine has been rearranged, thus eliminating the second and in some cases the third shaft. Further, the complete expansion and parts of the compression have been integrated in the fan blade. To assess the aero-thermodynamic parameters, a preliminary cycle analysis has been done, where the most influential parameters were varied. The results show, that the above listed benefits can be achieved while maintaining an efficiency comparable to conventional turbofans. Further, a feasibility study in terms of geometry, internal flow, component implementation and installation has been done, in order to qualify the concept and to identify the most critical aspects. To incorporate the corresponding thoughts and results, as well as to find and eliminate conceptual conflicts and opposing trends, a CAD model has been generated. Overall, the results are sound and encouraging, hence justifying future investigations. However, the Heron Fan concept also brings structural, thermal and aerodynamic challenges which are illustrated and briefly discussed, but still need detailed investigation.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123990467","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}

{"title":"Technology Application to MHPS Large Flame F Series Gas Turbine","authors":"K. Fujimoto, Yuya Fukunaga, Satoshi Hada, T. Ai, M. Yuri, J. Masada","doi":"10.1115/GT2018-77274","DOIUrl":"https://doi.org/10.1115/GT2018-77274","url":null,"abstract":"The development of gas turbines, Mitsubishi Hitachi Power Systems, Ltd. (MHPS) has continued to pursue and contribute to society in terms of global environmental conservation and stable energy supply. MHPS leverages its abundant gas turbine operation experience and takes advantage of its extensive advanced technologies research on the Japanese National Project.\u0000 MHPS has been participating in this project since 2004. Recent years’ achievements include the demonstration of a gas turbine combined cycle (GTCC) efficiency in excess of 62% created by increasing the turbine inlet temperature to the 1,600°C class in the M501J in 2011.\u0000 The Latest M701F incorporates “J” gas turbine technologies, already applied to actual equipment, for efficiency improvement. It also applies air-cooled combustor technologies successfully validated in the G class, for increased flexibility. The 1st unit started commercial operation in 2015 and currently 4 units has accumulated more than 46,000 actual operating hours collectively.\u0000 MHPS is making the upgrading program for existing F-series gas turbines. The proven technology verified in the M501J and developed in the National project increases efficiency and reliability.\u0000 This paper explains the features and development status of Latest M701F gas turbine, and explains upgrade program for existing F-series gas turbines.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126007445","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}

{"title":"Thermal Stability Analysis of Gevo Jet Fuel Using Ellipsometry","authors":"L. Nash, J. Klettlinger, Subith S. Vasu","doi":"10.1115/GT2018-76209","DOIUrl":"https://doi.org/10.1115/GT2018-76209","url":null,"abstract":"Thermal stability is an important characteristic of alternative fuels that must be evaluated before they can be used in aviation engines. This characteristic is of great importance to the effectiveness of the fuel as a coolant and to the engine’s combustion performance. In this work, the thermal stability of Gevo fuel, an alcohol to jet fuel made from plant derived feedstock, was studied. This analysis was used to comment on the effectiveness of the current thermal stability test standard. This work was performed using a spectroscopic ellipsometer to measure the thickness of deposits left on aluminum substrates. It was observed that Gevo deposit thickness increased slowly up to 375 °C and much more rapidly after that point. Similar behavior was observed in JP-8 fuel. Comparisons were also made between color standard ratings and ellipsometric thickness measurements, and it was found that in some cases, darker colors did not indicate thicker deposits. Reference tubes were used to validate the optical models used in this work, and different optical constants were found to best model the results than what are published in the ASTM D3241 test method for thermal stability.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125225524","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}

{"title":"Performance Simulation and Analysis of a Gas Turbine Engine Using Drop-In Bio-Fuels","authors":"J. Rubie, Yi-Guang Li, A. Jackson","doi":"10.1115/GT2018-75751","DOIUrl":"https://doi.org/10.1115/GT2018-75751","url":null,"abstract":"There is an increasing dependence on conventional fuels for aviation. In order for a country’s air force to sustain a steady and a secure supply of fuel for aircraft with foresight into the future, alternate sources of fuels must be considered. This paper describes a thermodynamic performance simulation method and analysis of a model military aero gas turbine engine operating in several off-design modes while employing various types of blended fuels between Jet A and alternate bio-fuels, including Synthetic Paraffinic Kerosene (SPK) from Algae (Bio-Algae), Jatropha (JSPK) and Camelina (CSPK). These fuels are already approved by American Society for Testing and Materials (AS™) for blending with 50% Jet A fuel. A thermodynamic performance model for the model engine similar to GE F404-400 turbofan engine has been set up using Pythia, a Cranfield University created performance simulation software implemented with multiple fuel capabilities. The simulated performance and a comparative study shows that the performance of the model engine using blended fuels between Jet A and a bio-fuel were found to be equal or better than that using pure conventional fuel Jet A. The key hot section temperatures, pressures and the fuel consumption of the model engine were found to be slightly lower with the blended fuels than that using Jet A.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"25 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128545064","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}

{"title":"Design of a Closed-Loop Optical-Access Supersonic Test Facility for Organic Vapours","authors":"M. White, A. Sayma","doi":"10.1115/GT2018-75301","DOIUrl":"https://doi.org/10.1115/GT2018-75301","url":null,"abstract":"Despite significant research activities into organic Rankine cycles for the conversion of low-temperature heat into power, there remain uncertainties with regards to non-ideal gas effects and their role in turbine performance. Moreover, existing performance models and numerical solvers have yet to be validated for turbines operating with organic fluids. This paper documents the design of a closed-loop supersonic test facility intended for experimental characterisation of the flow of organic fluids under typical operating conditions experienced within an ORC turbine. The test section forms part of a wider test facility, developed for the study of ORC expanders, which includes a screw compressor, the supersonic test section, a heat exchanger and an expander test section. The working fluid is R1233zd, and the test facility is sized to deliver test conditions up to 20 bar and 125 °C with a mass-flow rate of 1 kg/s. After an overview of the test facility, the detailed design of the upstream diffuser, settling chamber, contraction zone and converging-diverging nozzle to deliver a flow with a Mach number of 2 to the test section is discussed. The performance of the test section is confirmed by CFD simulations. Finally, the intended flow visualisation using particle-image velocimetry is discussed. This includes the identification of a suitable seeding method considering both liquid and solid tracer particles. The assessment is completed considering constraints such as the operating conditions, the required particle size to accurately trace the fluid flow, maintenance issues, and compatibility with the working fluid. In particular, the possibility of using the compressor lubricating oil as the seeding particle is evaluated.","PeriodicalId":131179,"journal":{"name":"Volume 3: Coal, Biomass, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126433681","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}