SAE transactions最新文献

{"title":"Design of A Fuel Vapor-containment System (FVS) to Meet Zero Evaporative Emissions Requirements in a Hybrid Electric Vehicle","authors":"Yojiro Iriyama, Masahide Kobayashi, T. Matsubara, Yuusaku Nishimura, Ryosuke Nomura, Takashi Ishikawa","doi":"10.4271/2005-01-3825","DOIUrl":"https://doi.org/10.4271/2005-01-3825","url":null,"abstract":"Generally Hybrid Electrical Vehicles (HEV's) tend to have difficulty with regard to evaporative emissions because they have less capability of purging canisters compared with that of conventional systems. Toyota has developed a new fuel system that can address this difficulty and enables outstanding performance for the new-generation HEV. The fuel system, called the \"Fuel Vapor-containment System (FVS)\", consists of newly developed or redesigned components, such as a high strength fuel tank, a Fuel Vapor-containment Valve (FW), refueling canister and a purge buffer as well as newly defined controls of the components for the vehicle. The fuel tank is sealed while a vehicle is parked and fuel vapor does not flow into the canister by control of the FVV, except during refueling events. Therefore, HEV's do not have to ensure as much as purge capacity to achieve the necessary lower evaporative requirements. As a result, an HEV can provide low fuel consumption and environmental-friendliness which meets Super Ultra Low Emission Vehicle (SULEV) exhaust emissions requirements and zero evaporative emissions standards in California.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"8 1","pages":"1551-1558"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84796570","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 Effect of Water on Soot Formation Chemistry","authors":"C. Roberts, D. Naegeli, Christopher J. Chadwell","doi":"10.4271/2005-01-3850","DOIUrl":"https://doi.org/10.4271/2005-01-3850","url":null,"abstract":"A combined, experimental and numerical program is presented. This work summarizes an internal research effort conducted at Southwest Research Institute. Meeting new, stringent emissions regulations for diesel engines requires a way to reduce NO x and soot emissions. Most emissions reduction strategies reduce one pollutant while increasing the other. Water injection is one of the few promising emissions reduction techniques with the potential to simultaneously reduce soot and NO x in diesel engines. While it is widely accepted that water reduces NO x via a thermal effect, the mechanisms behind the reduction of soot are not well understood. The water could reduce the soot via physical, thermal, or chemical effects. To aid in developing water injection strategies, this project's goal was to determine how water enters the soot formation chemistry. Linked burner experiments and modeling of a rich premixed flame were used to determine the magnitude of the thermal and chemical effect of water on soot formation and identify a possible kinetic mechanism to explain it. Following Dec's model for diesel combustion processes (Dec, 1997; Flynn, et al., 1999) [1,19] , soot inception results from rich premixed combustion; thus the rich premixed flame provides an appropriate venue in which to isolate the influence of water on the kinetics. Open flame, burner experiments have been performed to quantify the soot inception point and the relative amounts of soot formation in premixed flames with and without water addition. These results have been used to expand and compliment data available in the published literature. Subsequent modeling has been used to predict trends in soot inception using currently accepted kinetic soot mechanisms. Results from this effort led to a revised kinetic mechanism for the process. Comparison of the experimental and modeling data has been used to assess the accuracy of soot formation mechanisms and ultimately has yielded a new understanding of the soot formation chemistry and the role of added water.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"5 1","pages":"1656-1672"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91378791","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":"Cycle-Resolved Investigation of In-Cylinder and Exhaust NO in a Spray-Guided Gasoline Direct-Injection Engine: Effect of Intake Temperature and Simulated Exhaust Gas Recirculation","authors":"Udo Fissenewert, V. Sick","doi":"10.4271/2005-01-3685","DOIUrl":"https://doi.org/10.4271/2005-01-3685","url":null,"abstract":"The formation of NO was investigated in a spray-guided spark-ignition direct-injection gasoline engine. The influence of variations in intake air temperature and simulated exhaust gas recirculation was examined in an optical single-cylinder engine, fueled with iso-octane. Cycle-resolved simultaneous measurements of OH-chemiluminescence, NO laser induced fluorescence, and fast NO exhaust gas sampling allowed a detailed view of the formation process of NO in this engine. Overall, it was found that cycle-resolved information is needed to explain the differences found between operating conditions, since the initial high stratification of fuel leads to large spatial gradients in the NO concentration. Averaged in-cylinder NO distributions do not adequately reflect the formation process rather than show a smoothed distribution that may even be counter-intuitive based on averaged chemiluminescence data. The strong impact of the high level of fuel stratification is also reflected in the temporal evolution of the in-cylinder NO concentrations. Spatially averaged peak concentrations can reach 2700 ppm for engine operation with 90 °C intake air temperature and no EGR. This compares to approximately 300 ppm as measured in the exhaust gas. This ratio is high for spark-ignition engines. However, given the high level of fuel stratification in this spray-guided engine, the observations are plausible and are supported by the measured high local concentrations of NO.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"38 1","pages":"1213-1228"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82287684","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":"A New Flame Jet Concept to Improve the Inflammation of Lean Burn Mixtures in SI Engines","authors":"M. Kettner, M. Rothe, A. Velji, U. Spicher, D. Kuhnert, R. Latsch","doi":"10.4271/2005-01-3688","DOIUrl":"https://doi.org/10.4271/2005-01-3688","url":null,"abstract":"Engines with gasoline direct injection promise an increase in efficiency mainly due to the overall lean mixture and reduced pumping losses at part load. But the near stoichiometric combustion of the stratified mixture with high combustion temperature leads to high NO x emissions. The need for expensive lean NO x catalysts in combination with complex operation strategies may reduce the advantages in efficiency significantly. The Bowl-Prechamber-lgnition (BPI) concept with flame jet ignition was developed to ignite premixed lean mixtures in DISI engines. The mainly homogeneous lean mixture leads to low combustion temperatures and subsequently to low NO x emissions. By additional EGR a further reduction of the combustion temperature is achievable. The BPI concept is realized by a prechamber spark plug and a piston bowl. The main feature of the concept is its dual injection strategy. A preinjection in the inlet stroke leads to a homogeneous lean mixture with an air-fuel ratio of λ = 1.4 to λ = 1.7. During the compression stroke a second direct injection with a small amount of fuel (about 3 % of the total fuel mass) is directed towards the piston bowl. The enriched air fuel mixture in the piston bowl is transported by the piston motion towards the prechamber spark plug. Due to the pressure difference between main combustion chamber and prechamber the mixture is transported with a highly turbulent flow into the prechamber. After reliable ignition of the enriched mixture in the prechamber, flame jets penetrate into the main combustion chamber and ignite the lean mixture. Numerical and experimental investigations were carried out in a modified 3-valve single cylinder engine for part load operation. The in-cylinder flow including the mixture process in the main combustion chamber and in the prechamber was investigated by CFD simulation, so that the local mixture composition could be predicted. With extended test runs and measurements the functionality of the BPI concept has been proved. For the quantification of the mixture enrichment in the prechamber spark plug ion current measurement has been found as an appropriate measurement tool [11][12]. At part load operation in BPI mode significant reductions in fuel consumption and NOx emission have been achieved compared to stoichiometric operation. Further investigations at full load have been carried out on a single cylinder engine and a 4-cylinder production engine to analyse the influence of prechamber spark plugs on one hand and the influence of lean operation on the other hand on the engine process. Homogeneous full load operation with the prechamber spark plug has shown a reduction in knock sensitivity. Due to significantly reduced cyclic fluctuations the maximum knock amplitudes at the knock limit was reduced.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"240 1","pages":"1549-1557"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80456611","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":"Transient ultrafine particle emission measurements with a new fast particle aerosol sizer for a trap equipped diesel truck","authors":"A. Ayala, J. Herner","doi":"10.4271/2005-01-3800","DOIUrl":"https://doi.org/10.4271/2005-01-3800","url":null,"abstract":"The California Air Resources Board (CARB) has tested the utility of the Model 3090 Engine Exhaust Particle Sizer (EEPS™) by TSI in measuring pre- and post-trap particulate matter (PM) emissions from a medium-duty truck. Pre- and post-trap measurements are used to evaluate the effect of engine operation on PM emissions and trap effectiveness. Because of mounting evidence that ultrafine (UF) particles are harmful, regulatory agencies are investigating new and promising instrumentation for improved characterization of such particles in emissions. This is especially true for fast-response instruments that can be used to size-resolve real-time UF emissions from prominent sources such as diesel engines. The EEPS uses diffusion charging, electrical mobility segregation, and electrometers. It is designed for the number measurement of transient aerosols in the size range of 5.6 to 560 nm. It collects 10 measurements per second at a flow rate of 10 Ipm. We sampled the emissions from a model year 2000 Isuzu medium-heavy-duty delivery truck. The truck was retrofitted with a Johnson Matthey Continuously Regenerative Trap (CRT\") and fueled by ultra low sulfur diesel (ULSD). Pre- and post-trap partial-flow samples of raw exhaust were taken using a double-stage Dekati diluter. Primary and secondary dilution ratios of approximately 8 each resulted in a total dilution of 64:1. The vehicle was operated over steady-state (50 mph cruise and idle) and transient (CBD and NYBC) duty cycles. The EEPS measurements suggest that without a trap, the size of the particles emitted by the diesel engine is highly dependent on the driving cycle. Emissions of particles smaller than 120 nm were greatest during accelerations and emissions of particles larger than 250 nm were greatest during decelerations and idle. Bursts of particularly high emissions of particles smaller than 10 nm were seen immediately after accelerations. The pre-trap size distribution was bi-modal during both steady state and transient engine operation. Peak concentrations were observed at or below 10 nm and at 60 nm at concentrations, uncorrected for dilution, of 10 5 -10 6 N/cc. The post-trap size distribution and concentration did not change significantly as a function of driving cycles. The post-trap size distribution was bi-modal with peaks at 10 and 30 nm and peak concentration of 10 2 N/cc. The EEPS measurements showed substantial effectiveness of the CRT in reducing both transient and steady-state UF particle emissions over the entire size range. In the current study the CRT reduced the total number concentrations by two to three orders of magnitude.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"87 6 1","pages":"1525-1533"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84029898","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":"Emissions of Toxicologically Relevant Compounds Using Fischer-Tropsch Diesel Fuel and Aftertreatment at a Low NOx, Low Power Engine Condition","authors":"J. C. Ball, T. E. Kenney, Leslie R. Wolf, D. Yost, M. Schulman, E. Frame, J. P. Wallace, D. Hilden, M. Natarajan, T. Johnson, Kenneth J. Wright, K. Eng, A. D. González","doi":"10.4271/2005-01-3764","DOIUrl":"https://doi.org/10.4271/2005-01-3764","url":null,"abstract":"Previously we reported (SAE Paper 2005-01-0475) that emissions of toxicologically relevant compounds from an engine operating at low NOx conditions using Fischer-Tropsch fuel (FT100) were lower than those emissions from the engine using an ultra-low sulfur (15 PPM sulfur) diesel fuel (BP15). Those tests were performed at two operating modes: Mode 6 (4.2 bar BMEP, 2300 RPM) and Mode 11 (2.62 bar BMEP, 1500 RPM). We wanted to evaluate the effect on emissions of operating the engine at low power (near idle) in conjunction with the low NOx strategy. Specifically, we report on emissions of total hydrocarbon (HC), carbon monoxide (CO), NOx, particulates (PM), formaldehyde, acetaldehyde, benzene, 1,3-butadiene, gas phase polyaromatic hydrocarbons (PAH's) and particle phase PAH's from a DaimlerChrysler OM611 CIDI engine using a low NOx engine operating strategy at Mode 22 (1.0 bar BMEP and 1500 RPM). Mode 22 did produce some differences in emissions levels and aftertreatment performance for toxicologically relevant species compared to Modes 6 and 11. Further, uncontrolled step changes in these emissions were observed to occur at the low exhaust temperature of Mode 22. Nevertheless the emissions for Mode 22 with Fischer-Tropsch diesel fuel were generally consistent with Modes 6 and 11.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"11 1","pages":"1426-1449"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76057729","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":"Investigation of Boundary Layer Behaviour in HCCI Combustion using Chemiluminescence Imaging","authors":"H. Persson, Leif Hildingsson, Anders Hultqvist, B. Johansson, Jochen Ruebel","doi":"10.4271/2005-01-3729","DOIUrl":"https://doi.org/10.4271/2005-01-3729","url":null,"abstract":"Investigation of Boundary Layer Behavior in Hcci Combustion Using Chemiluminescence Imaging","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"1 1","pages":"1358-1369"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79808412","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":"Final Operability and Chassis Emissions Results from a Fleet of Class 6 Trucks Operating on Gas-to-Liquid Fuel and Catalyzed Diesel Particle Filters","authors":"T. Alleman, R. Barnitt, L. Eudy, M. Miyasato, A. Oshinuga, Tom Corcoran, S. Chatterjee, Todd Jacobs, R. A. Cherrillo, N. Clark, W. Wayne","doi":"10.4271/2005-01-3769","DOIUrl":"https://doi.org/10.4271/2005-01-3769","url":null,"abstract":"Six 2001 International Class 6 trucks participated in a project to determine the impact of gas-to-liquid (GTL) fuel and catalyzed diesel particle filters (DPFs) on emissions and operations from December 2003 through August 2004. The vehicles operated in Southern California and were nominally identical. Three vehicles operated \"as-is\" on California Air Resources Board (CARB) specification diesel fuel and no emission control devices. Three vehicles were retrofit with Johnson Matthey CCRT® (Catalyzed Continuously Regenerating Technology) filters and fueled with Shell GTL Fuel. Two rounds of emissions tests were conducted on a chassis dynamometer over the City Suburban Heavy Vehicle Route (CSHVR) and the New York City Bus (NYCB) cycle. The CARB-fueled vehicles served as the baseline, while the GTL-fueled vehicles were tested with and without the CCRT filters. Results from the first round of testing have been reported previously (see 2004-01-2959). The second round results were compared to the CARB specification diesel fuel baseline. Over the CSHVR cycle, the GTL Fuel (no filter) reduced oxides of nitrogen (NO x ), hydrocarbon (HC), and particulate matter (PM) emissions by 13%, 46%, and 21%, respectively, and increased carbon monoxide (CO) by 11%. The GTL Fuel and the CCRT filter virtually eliminated the HC, CO, and PM emissions and reduced NO x emissions by 22%, a statistically significant reduction. Testing over the NYCB cycle also revealed emission reductions are possible with GTL Fuel. Compared to the CARB specification diesel fuel, the GTL Fuel provided statistically significant reductions in NO x , HC, and PM emissions by 11%, 58%, and 16%, respectively. A 10% increase in CO emissions was also noted, although not statistically significant. With the CCRT filter, the HC, CO, and PM emissions were reduced by over 95%. A statistically significant NO x reduction of 20% was observed. Reductions from round 2 were notably larger than those in round 1. To determine if the changes observed between rounds were \"real\", a statistical analysis was performed. The analysis found that CO emissions were higher without the filter in round 2, while no changes were observed for HC or PM emissions. The NO x emissions were significantly higher in round 1 for the NYCB cycle only. The fleet was followed for operability for 6 months and accumulated -20,000 miles. Driver feedback for the vehicles operating on the GTL Fuel and CCRT filters was very positive. An analysis determined that the fuel economy with the combination of GTL Fuel and CCRT filters decreased by 8%. Evaluation of the maintenance records did not reveal any impact of the GTL fuel or CCRT filters on operability.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"8 1","pages":"1450-1463"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72764369","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 Quantification of Mixture Stoichiometry When Fuel Molecules Contain Oxidizer Elements or Oxidizer Molecules Contain Fuel Elements","authors":"C. Mueller","doi":"10.4271/2005-01-3705","DOIUrl":"https://doi.org/10.4271/2005-01-3705","url":null,"abstract":"The accurate quantification and control of mixture stoichiometry is critical in many applications using new combustion strategies and fuels (e.g., homogeneous charge compression ignition, gasoline direct injection, and oxygenated fuels). The parameter typically used to quantify mixture stoichiometry (i.e., the proximity of a reactant mixture to its stoichiometric condition) is the equivalence ratio, Φ. The traditional definition of Φ is based on the relative amounts of fuel and oxidizer molecules in a mixture. This definition provides an accurate measure of mixture stoichiometry when the fuel molecule does not contain oxidizer elements and when the oxidizer molecule does not contain fuel elements. However, the traditional definition of θ leads to problems when the fuel molecule contains an oxidizer element, as is the case when an oxygenated fuel is used, or once reactions have started and the fuel has begun to oxidize. The problems arise because an oxidizer element in a fuel molecule is counted as part of the fuel, even though it is an oxidizer element. Similarly, if an oxidizer molecule contains fuel elements, the fuel elements in the oxidizer molecule are misleadingly lumped in with the oxidizer in the traditional definition of Φ. In either case, use of the traditional definition of Φ to quantify the mixture stoichiometry can lead to significant errors. This paper introduces the oxygen equivalence ratio, Φ Ω , a parameter that properly characterizes the instantaneous mixture stoichiometry for a broader class of reactant mixtures than does Φ. Because it is an instantaneous measure of mixture stoichiometry, Φ Ω can be used to track the time-evolution of stoichiometry as a reaction progresses. The relationship between Φ Ω and Φ is shown. Errors are involved when the traditional definition of Φ is used as a measure of mixture stoichiometry with fuels that contain oxidizer elements or oxidizers that contain fuel elements; Φ Ω is used to quantify these errors. Proper usage of Φ Ω is discussed, and Φ Ω is used to interpret results in a practical example.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"124 2 1","pages":"1243-1252"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89418055","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":"A Thermal Response Analysis on the Transient Performance of Active Diesel Aftertreatment","authors":"M. Zheng, G. Reader, Dong Wang, J. Zuo, Raj Kumar, M. Mulenga, U. Asad, D. Ting, Meiping Wang","doi":"10.4271/2005-01-3885","DOIUrl":"https://doi.org/10.4271/2005-01-3885","url":null,"abstract":"Diesel fueling and exhaust flow strategies are investigated to control the substrate temperatures of diesel aftertreatment systems. The fueling control includes the common-rail post injection and the external supplemental fuel injection. The post injection pulses are further specified at the early, mid, or late stages of the engine expansion stroke. In comparison, the external fueling rates are moderated under various engine loads to evaluate the thermal impact. Additionally, the active-flow control schemes are implemented to improve the overall energy efficiency of the system. In parallel with the empirical work, the dynamic temperature characteristics of the exhaust system are simulated one-dimensionally with in-house and external codes. The dynamic thermal control, measurement, and modeling of this research intend to improve the performance of diesel particulate filters and diesel NOx absorbers.","PeriodicalId":21404,"journal":{"name":"SAE transactions","volume":"60 1","pages":"1804-1815"},"PeriodicalIF":0.0,"publicationDate":"2005-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89195928","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}