This paper presents a mathematical analysis to predict the solder fillet shape for ceramic ball grid array joints. Unlike the past analyses, the solder fillet is not assumed to be linear. The solder fillets on both the module and the card side are represented as arcs, and the solder shape is calculated from an analysis that incorporates the major factors affecting the solder fillet, including the solder volume, the pad size, the solder ball size, the wetting angle between the solder and the solder ball, and the gap between the solder ball and the pad. Three of these parameters (the card pad size, the solder ball size and the card-side eutectic solder volume) were selected for investigation of their effect on the reliability of solder joints. To this end, a central composite design of experiment was set up, and the mathematical analysis and finite element methods were used to predict the fatigue life corresponding to each of the design settings in the design array. The results of analyzing the data reveal that the solder volume, the solder ball size and their interaction are statistically significant; the interaction between the pad size and the solder volume is also significant but to a less degree; the pad size and the interaction between the pad size and the solder ball size are not significant. In addition, a response surface model was built to find the optimum settings for maximum reliability. Finally, inaccuracy due to the linear solder fillet assumption is assessed in light of the present analysis.
{"title":"CBGA Solder Fillet Shape Prediction and Design Optimization","authors":"Y. Li, R. Mahajan","doi":"10.1115/1.2792592","DOIUrl":"https://doi.org/10.1115/1.2792592","url":null,"abstract":"\u0000 This paper presents a mathematical analysis to predict the solder fillet shape for ceramic ball grid array joints. Unlike the past analyses, the solder fillet is not assumed to be linear. The solder fillets on both the module and the card side are represented as arcs, and the solder shape is calculated from an analysis that incorporates the major factors affecting the solder fillet, including the solder volume, the pad size, the solder ball size, the wetting angle between the solder and the solder ball, and the gap between the solder ball and the pad. Three of these parameters (the card pad size, the solder ball size and the card-side eutectic solder volume) were selected for investigation of their effect on the reliability of solder joints. To this end, a central composite design of experiment was set up, and the mathematical analysis and finite element methods were used to predict the fatigue life corresponding to each of the design settings in the design array. The results of analyzing the data reveal that the solder volume, the solder ball size and their interaction are statistically significant; the interaction between the pad size and the solder volume is also significant but to a less degree; the pad size and the interaction between the pad size and the solder ball size are not significant. In addition, a response surface model was built to find the optimum settings for maximum reliability. Finally, inaccuracy due to the linear solder fillet assumption is assessed in light of the present analysis.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"55 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":"114337174","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}
Residual stress distributions due to plating and polishing were determined for nickel-phosphorus plated aluminum alloy disks. Knowledge of these stresses provides insight into the material deformation and removal processes, information as to the effects of processing conditions on residual stress magnitude and can also serve as a basis for development of models of material deformation and removal in polishing. Measured disk shape data was fitted to an analytical solution for plate displacement due to bending moments, and residual stresses were calculated. Plating and polishing residual stresses were separated. Polishing residual stress is compressive indicating differential plastic deformation between the surface and interior regions of the workpiece. Residual stresses produced in polishing operations in which process motions were constrained so that polishing was unidirectional were measured. The results show large differences between amounts of deformation in the polishing direction and the direction perpendicular to it.
{"title":"Residual Stresses and Workpiece Deformation due to Polishing and Plating of Computer Hard Disk Substrates","authors":"B. Klamecki","doi":"10.1115/1.2830572","DOIUrl":"https://doi.org/10.1115/1.2830572","url":null,"abstract":"Residual stress distributions due to plating and polishing were determined for nickel-phosphorus plated aluminum alloy disks. Knowledge of these stresses provides insight into the material deformation and removal processes, information as to the effects of processing conditions on residual stress magnitude and can also serve as a basis for development of models of material deformation and removal in polishing. Measured disk shape data was fitted to an analytical solution for plate displacement due to bending moments, and residual stresses were calculated. Plating and polishing residual stresses were separated. Polishing residual stress is compressive indicating differential plastic deformation between the surface and interior regions of the workpiece. Residual stresses produced in polishing operations in which process motions were constrained so that polishing was unidirectional were measured. The results show large differences between amounts of deformation in the polishing direction and the direction perpendicular to it.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"1 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":"116482428","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}
A simple dynamic model to describe the grinding behavior in bound abrasive microgrinding of optical materials with CNC (Computerized Numerical Control) machining equipment is discussed and compared with data collected from direct measurement of grinding force. The model involves the relation between grinding force and material removal rate, machine stiffness, and tool condition. Measurements have shown that the tool’s effectiveness and the workpiece surface quality are closely tied through the normal load exerted by the tool on the workpiece during grinding.
{"title":"A Dynamic Model for Bound Abrasive Grinding of Optical Materials: The Effect of Grinding Conditions on the Workpiece Surface Quality","authors":"Toshio Takahashi, P. Funkenbusch","doi":"10.1115/imece1997-1099","DOIUrl":"https://doi.org/10.1115/imece1997-1099","url":null,"abstract":"\u0000 A simple dynamic model to describe the grinding behavior in bound abrasive microgrinding of optical materials with CNC (Computerized Numerical Control) machining equipment is discussed and compared with data collected from direct measurement of grinding force. The model involves the relation between grinding force and material removal rate, machine stiffness, and tool condition. Measurements have shown that the tool’s effectiveness and the workpiece surface quality are closely tied through the normal load exerted by the tool on the workpiece during grinding.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"39 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":"116231435","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. Ramabhadran, R. R. Hebbar, R. Kashyap, S. Chandrasekar
We present a method for estimating the quality of a measured discharge train in Micro-EDM processes. In contrast to generic EDM, Micro-EDM is characterized by a higher frequency of discharges and is used for machining smaller features, thus making regulation more difficult. In this paper, a system similar to a fuzzy rule based classification is used to identify good and bad disharges based on discharge quality. In addition to traditional machining quality issues, we include parameters that illustrate the degree of control of the voltage pulse input over the spark gap. To aid the formulation of quick closed loop control schemes for Micro-EDM, a method for identifying the parameter/sensor that separates best the good and bad discharges, is presented. The use of this method in closed loop control schemes for Micro-EDM is discussed.
{"title":"Discharge Quality Estimation and Significant Feature Identification in Micro-Electrical Discharge Machining","authors":"R. Ramabhadran, R. R. Hebbar, R. Kashyap, S. Chandrasekar","doi":"10.1115/imece1997-1106","DOIUrl":"https://doi.org/10.1115/imece1997-1106","url":null,"abstract":"\u0000 We present a method for estimating the quality of a measured discharge train in Micro-EDM processes. In contrast to generic EDM, Micro-EDM is characterized by a higher frequency of discharges and is used for machining smaller features, thus making regulation more difficult. In this paper, a system similar to a fuzzy rule based classification is used to identify good and bad disharges based on discharge quality. In addition to traditional machining quality issues, we include parameters that illustrate the degree of control of the voltage pulse input over the spark gap. To aid the formulation of quick closed loop control schemes for Micro-EDM, a method for identifying the parameter/sensor that separates best the good and bad discharges, is presented. The use of this method in closed loop control schemes for Micro-EDM is discussed.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"108 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":"116789264","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 paper deals with the monitoring technologies for making the grinding process more intelligent and reliable by applying the sensor fusion and artificial intelligence technologies. Increase of the practical application of CBN wheels requires a development of reliable monitoring system to utilize expensive abrasives more efficiently. Combination of an acoustic emission sensor and a power sensor makes the judgment of the wheel life possible with high reliability. One of the characteristic features of the proposed monitoring system is that the acoustic emission sensor is integrated in the CBN wheel, which makes it possible to detect a reliable signal. Monitoring of the dressing process is made possible by applying the same system. Concept of the intelligent data base system based on the genetic algorithms and fuzzy production rules is proposed.
{"title":"Monitoring Technology for Achieving Intelligent Grinding System","authors":"I. Inasaki","doi":"10.1115/imece1997-1078","DOIUrl":"https://doi.org/10.1115/imece1997-1078","url":null,"abstract":"\u0000 The paper deals with the monitoring technologies for making the grinding process more intelligent and reliable by applying the sensor fusion and artificial intelligence technologies. Increase of the practical application of CBN wheels requires a development of reliable monitoring system to utilize expensive abrasives more efficiently. Combination of an acoustic emission sensor and a power sensor makes the judgment of the wheel life possible with high reliability. One of the characteristic features of the proposed monitoring system is that the acoustic emission sensor is integrated in the CBN wheel, which makes it possible to detect a reliable signal. Monitoring of the dressing process is made possible by applying the same system. Concept of the intelligent data base system based on the genetic algorithms and fuzzy production rules is proposed.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"5 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":"125202204","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}
Thermally-induced failure is a major reliability issue for electronic packaging. Due to highly nonlinearity of packaging materials, the electronic packages exhibit uneven thermal deformation in the whole temperature range during thermal cycling. This behavior will affect the buildup of thermal strain and thermal stress within packages, which may affect the reliability of the packaging. Therefore, a real time method is needed to monitor the thermal deformation of packages during the thermal cycling. In this study, the real time moiré interferometry technique is used to monitor the thermal deformation of a plastic package. A grating is transferred onto the cross section of the sample at room temperature. Then the sample is placed in a thermal vacuum chamber and the temperature is increased from room temperature to high temperature. A moiré interferometry setup is used to monitor the thermal deformation of the package with the increase of temperature. The fringe patterns are recorded by a CCD camera system and are compared with the displacement contours of nonlinear finite element simulations. The results show that the real time moiré interferometry technique is an effective way to monitor the thermal deformation of electronic packaging and also provide a powerful validation method for finite element analysis. The comparison between the moiré fringe patterns and finite element results also shows a good agreement.
{"title":"Real Time Monitoring and Simulation of Thermal Deformation in Plastic Package","authors":"Jiansen Zhu, D. Zou, Sheng Liu","doi":"10.1115/imece1997-1111","DOIUrl":"https://doi.org/10.1115/imece1997-1111","url":null,"abstract":"\u0000 Thermally-induced failure is a major reliability issue for electronic packaging. Due to highly nonlinearity of packaging materials, the electronic packages exhibit uneven thermal deformation in the whole temperature range during thermal cycling. This behavior will affect the buildup of thermal strain and thermal stress within packages, which may affect the reliability of the packaging. Therefore, a real time method is needed to monitor the thermal deformation of packages during the thermal cycling. In this study, the real time moiré interferometry technique is used to monitor the thermal deformation of a plastic package. A grating is transferred onto the cross section of the sample at room temperature. Then the sample is placed in a thermal vacuum chamber and the temperature is increased from room temperature to high temperature. A moiré interferometry setup is used to monitor the thermal deformation of the package with the increase of temperature. The fringe patterns are recorded by a CCD camera system and are compared with the displacement contours of nonlinear finite element simulations. The results show that the real time moiré interferometry technique is an effective way to monitor the thermal deformation of electronic packaging and also provide a powerful validation method for finite element analysis. The comparison between the moiré fringe patterns and finite element results also shows a good agreement.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"10 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":"129428723","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}
Literaturally, the local-global finite element analysis technique plays a very important role in the area array packaging. This technique applies a finite element based method to calculate the geometrical data and elastic/plastic material properties of the equivalent beam model that is used to elastically and plastically simulate the 3-D local model. In this study, the underlying goal is to propose an improved equivalent model for the use in the local/global analysis, and most importantly, provide a systematic procedure in approaching this equivalent model. In addition, the choice of the equivalent beam model (i.e., either solid circular beam or the thin-walled circular pipe) will be also extensively investigated. Since the configuration of the solder joint is far from being close to a “beam-like” structure, defining the corresponding equivalent beam exists a great level of difficulties. Hence, in order to remove the possible difficulties, a comparatively effective way is proposed by incorporating the analytical derivations and optimization approaches. To this end, one practical application is presented to substantiate the proposed methodology.
{"title":"On the Equivalent Finite Element Beam Model for Ball Grid Array Analysis","authors":"Hsien-Chie Cheng, K. Chiang, Ming-Hisao Lee","doi":"10.1115/imece1997-1110","DOIUrl":"https://doi.org/10.1115/imece1997-1110","url":null,"abstract":"\u0000 Literaturally, the local-global finite element analysis technique plays a very important role in the area array packaging. This technique applies a finite element based method to calculate the geometrical data and elastic/plastic material properties of the equivalent beam model that is used to elastically and plastically simulate the 3-D local model. In this study, the underlying goal is to propose an improved equivalent model for the use in the local/global analysis, and most importantly, provide a systematic procedure in approaching this equivalent model. In addition, the choice of the equivalent beam model (i.e., either solid circular beam or the thin-walled circular pipe) will be also extensively investigated. Since the configuration of the solder joint is far from being close to a “beam-like” structure, defining the corresponding equivalent beam exists a great level of difficulties. Hence, in order to remove the possible difficulties, a comparatively effective way is proposed by incorporating the analytical derivations and optimization approaches. To this end, one practical application is presented to substantiate the proposed methodology.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"20 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":"126302941","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}
This paper describes an interactive neural network based system for specifying robotic tasks using virtual tools. This virtual environment allows an operator to reach into a live video scene and direct robots to use corresponding real tools to carry out complex metal finishing tasks. The virtual tool concept provides a human-machine interface that is robust to unanticipated developments and tunable to the specific requirements of a particular task. This interactive specification concept is applied to robotic deburring processes. A function is formulated to map the end-effector position of this robot to corresponding set of joint angles through a neural network learning process obtained through examples. The experimental result of such a system that has been implemented on the Mitsubishi RV-M1 robot shows the efficiency of the approach and its potential for use in virtual reality based interactive robotics.
{"title":"A Neural Network Based Interactive Programing of a Deburring Robot in a Virtual Environment","authors":"T. Kesavadas, Chin Khor","doi":"10.1115/imece1997-1101","DOIUrl":"https://doi.org/10.1115/imece1997-1101","url":null,"abstract":"\u0000 This paper describes an interactive neural network based system for specifying robotic tasks using virtual tools. This virtual environment allows an operator to reach into a live video scene and direct robots to use corresponding real tools to carry out complex metal finishing tasks. The virtual tool concept provides a human-machine interface that is robust to unanticipated developments and tunable to the specific requirements of a particular task. This interactive specification concept is applied to robotic deburring processes. A function is formulated to map the end-effector position of this robot to corresponding set of joint angles through a neural network learning process obtained through examples. The experimental result of such a system that has been implemented on the Mitsubishi RV-M1 robot shows the efficiency of the approach and its potential for use in virtual reality based interactive robotics.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"9 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":"121695322","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}
F. Kobayashi, F. Arai, T. Fukuda, M. Onoda, Norimasa Marui
Grinding process is frequently used to produce a smooth surface in the manufacturing system. Recently, for using a whetstone for a long time, grinding system needs to measure the surface roughness. However, it is difficult to measure the surface roughness and it takes a long time to measure it in process. Thus, we have to estimate surface roughness in process by online sensing information. In this paper, we propose a Recurrent Fuzzy Inference (RFI) with recurrent inputs and is applied to a multi-sensor fusion system for estimating the surface roughness. The membership functions of RFI are expressed by Radial Basis Function (RBF) with insensitive ranges. The learning method of RFI is based on the steepest descent method and incremental learning which can add new fuzzy rules. Where, the shape of new fuzzy rules is determined by the fitness of previous fuzzy rules.
{"title":"Online Estimation of Surface Roughness by Recurrent Fuzzy Inference in Grinding Process","authors":"F. Kobayashi, F. Arai, T. Fukuda, M. Onoda, Norimasa Marui","doi":"10.1115/imece1997-1074","DOIUrl":"https://doi.org/10.1115/imece1997-1074","url":null,"abstract":"\u0000 Grinding process is frequently used to produce a smooth surface in the manufacturing system. Recently, for using a whetstone for a long time, grinding system needs to measure the surface roughness. However, it is difficult to measure the surface roughness and it takes a long time to measure it in process. Thus, we have to estimate surface roughness in process by online sensing information. In this paper, we propose a Recurrent Fuzzy Inference (RFI) with recurrent inputs and is applied to a multi-sensor fusion system for estimating the surface roughness. The membership functions of RFI are expressed by Radial Basis Function (RBF) with insensitive ranges. The learning method of RFI is based on the steepest descent method and incremental learning which can add new fuzzy rules. Where, the shape of new fuzzy rules is determined by the fitness of previous fuzzy rules.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"17 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":"125059326","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}
A new shear angle prediction law is proposed for oblique cutting operations. Assuming a thin shear zone model, the oblique cutting mechanics are described by the five angles which show the directions of shear, resultant cutting force and chip flow. Five expressions required to solve the unknown angles are derived from the kinematics of oblique cutting and the physical law of deformation, i.e. either Maximum Shear Stress or Minimum Energy Principle. Unlike the previous solutions which require intuitive or empirical assumptions, the proposed methods use only the tool geometry and the material properties, i.e. shear yield stress and average chip-rake face friction coefficient. The predicted angles and forces agree well with the empirical and experimental results reported in the literature. Furthermore, the proposed models are experimentally verified in predicting forces for practical oblique helical end milling operations.
{"title":"Prediction of Shear Angle in Oblique Cutting With Maximum Shear Stress and Minimum Energy Principles","authors":"E. Shamoto, Y. Altintas","doi":"10.1115/1.2832695","DOIUrl":"https://doi.org/10.1115/1.2832695","url":null,"abstract":"\u0000 A new shear angle prediction law is proposed for oblique cutting operations. Assuming a thin shear zone model, the oblique cutting mechanics are described by the five angles which show the directions of shear, resultant cutting force and chip flow. Five expressions required to solve the unknown angles are derived from the kinematics of oblique cutting and the physical law of deformation, i.e. either Maximum Shear Stress or Minimum Energy Principle. Unlike the previous solutions which require intuitive or empirical assumptions, the proposed methods use only the tool geometry and the material properties, i.e. shear yield stress and average chip-rake face friction coefficient. The predicted angles and forces agree well with the empirical and experimental results reported in the literature. Furthermore, the proposed models are experimentally verified in predicting forces for practical oblique helical end milling operations.","PeriodicalId":432053,"journal":{"name":"Manufacturing Science and Engineering: Volume 1","volume":"60 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":"129732972","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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