Anna Ostaszewska-Liżewska, Dominika Kopala, R. Szewczyk
Tetrahedral meshing is the critical element of finite element modeling. Recently, adaptive meshing has been commonly used. In such meshing, according to the Delaunay method, mesh density is connected with the curvature of modeled object’s edge. Such a method is especially efficient during the modeling of mechanical systems. However, the efficiency of commonly used meshing algorithms is strongly limited in surface-focused phenomena, such as eddy current induced by magneto-dynamic processes. The paper proposes the improved method of Delaunay meshing considering the specific requirements of magnetodynamic systems. In the proposed method, tetrahedral mesh density may be flexibly modified according to the needs of modeled physical phenomena, such as eddy current density. As a result, physical effects may be efficiently and accurately described in finite element models. The paper presents the example of implementing the proposed solution for cylindrical wire. The complete source code is available as open-source software for further practical use and development.
{"title":"Improved Control of Mesh Density in Adaptive Tetrahedral Meshes for Finite Element Modeling","authors":"Anna Ostaszewska-Liżewska, Dominika Kopala, R. Szewczyk","doi":"10.14313/par_244/23","DOIUrl":"https://doi.org/10.14313/par_244/23","url":null,"abstract":"Tetrahedral meshing is the critical element of finite element modeling. Recently, adaptive meshing has been commonly used. In such meshing, according to the Delaunay method, mesh density is connected with the curvature of modeled object’s edge. Such a method is especially efficient during the modeling of mechanical systems. However, the efficiency of commonly used meshing algorithms is strongly limited in surface-focused phenomena, such as eddy current induced by magneto-dynamic processes. The paper proposes the improved method of Delaunay meshing considering the specific requirements of magnetodynamic systems. In the proposed method, tetrahedral mesh density may be flexibly modified according to the needs of modeled physical phenomena, such as eddy current density. As a result, physical effects may be efficiently and accurately described in finite element models. The paper presents the example of implementing the proposed solution for cylindrical wire. The complete source code is available as open-source software for further practical use and development.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"206 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125367398","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 presents a modification of the pressure-pressure (PP) sound intensity measurement method. In the proposed solution simultaneous measurement with a pair of microphones (used in the classical PP probe) is replaced by a sequence of measurements taken with a single microphone placed in successive positions. This approach requires an additional (reference) microphone to synchronize the successive measurements. Although, in the process of calculating the sound intensity only the signal from the measurement microphone is used. Thanks of this the errors associated with differences in the frequency responses of the measurement microphones (especially phase mismatch error) that occurs in the classical PP method are eliminated. This approach simultaneously increases the random error and limits the measurements to periodic signals only. The article presents the principle of operation of the classical PP probe and the currently used methods of phase mismatch error elimination based on pre-calibration of the probe. Next, the theoretical basis of the proposed measurement method is described. To verify the effectiveness of phase mismatch error elimination in the proposed method, an experiment was conducted. It consisted in estimation the angle of incidence of an acoustic wave under controlled conditions in an anechoic chamber. The measurement was carried out with the classical PP probe and with the modified method. Measurements were made for different sound sources (a loudspeaker set and a small electrical device). In the final part of the paper, the results are discussed, both methods (classical and modified) are compared and potential applications of the proposed method are indicated.
{"title":"Elimination of the Phase Mismatch Error in PP Probe Using Synchronous Measurement Technique","authors":"M. Raczyński","doi":"10.14313/par_244/35","DOIUrl":"https://doi.org/10.14313/par_244/35","url":null,"abstract":"The paper presents a modification of the pressure-pressure (PP) sound intensity measurement method. In the proposed solution simultaneous measurement with a pair of microphones (used in the classical PP probe) is replaced by a sequence of measurements taken with a single microphone placed in successive positions. This approach requires an additional (reference) microphone to synchronize the successive measurements. Although, in the process of calculating the sound intensity only the signal from the measurement microphone is used. Thanks of this the errors associated with differences in the frequency responses of the measurement microphones (especially phase mismatch error) that occurs in the classical PP method are eliminated. This approach simultaneously increases the random error and limits the measurements to periodic signals only. The article presents the principle of operation of the classical PP probe and the currently used methods of phase mismatch error elimination based on pre-calibration of the probe. Next, the theoretical basis of the proposed measurement method is described. To verify the effectiveness of phase mismatch error elimination in the proposed method, an experiment was conducted. It consisted in estimation the angle of incidence of an acoustic wave under controlled conditions in an anechoic chamber. The measurement was carried out with the classical PP probe and with the modified method. Measurements were made for different sound sources (a loudspeaker set and a small electrical device). In the final part of the paper, the results are discussed, both methods (classical and modified) are compared and potential applications of the proposed method are indicated.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117128687","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 work continues the series of publications on the estimation of the parameters of the equation and the limits of the uncertainty band of the straight-line y = ax + b fitted to the measurement results of both coordinates of the tested points with the use of the linear regression method. A general case was considered when these coordinates have different uncertainties and there are all possible autocorrelations and cross-correlations. Description of matrix equations was used. The results of the coordinate measurements are presented as elements of the X and Y vectors. The propagation of their uncertainty was described by the UZ covariance matrix with four component matrices, i.e., UX and UY – for the uncertainties and autocorrelations of X and of Y, and UXY and its transposition U – for the cross-correlations. The equation of a straight line and of the borders of its uncertainty band are given. Obtained them for the function of parameters a and b satisfying the so-called total criterion WTLS, i.e., the minimum sum of squared distances of points from the straight line weighted by the reciprocal of the coordinate uncertainty. When the coordinates of different points are not correlated, the simplified criterion WLS is used. The directions of projecting the points result from the minimization of the function describing the criterion. In the general case, there is only a numerical solution. This is illustrated by an example, in which the parameters a and b of the straight line were determined numerically from the enlarged fragments of the graph of the criterion function around its minimum. The conditions for the uncertainty and correlation of coordinates of points required to obtain an analytical solution and its example are also given.
{"title":"Regression and Uncertainty of a Straight-Line for Measurements of x and y Variables with All Correlations","authors":"J. Puchalski, Z. Warsza","doi":"10.14313/par_244/47","DOIUrl":"https://doi.org/10.14313/par_244/47","url":null,"abstract":"The work continues the series of publications on the estimation of the parameters of the equation and the limits of the uncertainty band of the straight-line y = ax + b fitted to the measurement results of both coordinates of the tested points with the use of the linear regression method. A general case was considered when these coordinates have different uncertainties and there are all possible autocorrelations and cross-correlations. Description of matrix equations was used. The results of the coordinate measurements are presented as elements of the X and Y vectors. The propagation of their uncertainty was described by the UZ covariance matrix with four component matrices, i.e., UX and UY – for the uncertainties and autocorrelations of X and of Y, and UXY and its transposition U – for the cross-correlations. The equation of a straight line and of the borders of its uncertainty band are given. Obtained them for the function of parameters a and b satisfying the so-called total criterion WTLS, i.e., the minimum sum of squared distances of points from the straight line weighted by the reciprocal of the coordinate uncertainty. When the coordinates of different points are not correlated, the simplified criterion WLS is used. The directions of projecting the points result from the minimization of the function describing the criterion. In the general case, there is only a numerical solution. This is illustrated by an example, in which the parameters a and b of the straight line were determined numerically from the enlarged fragments of the graph of the criterion function around its minimum. The conditions for the uncertainty and correlation of coordinates of points required to obtain an analytical solution and its example are also given.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129650856","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}
Dominika Kopala, Anna Ostaszewska-Liżewska, R. Szewczyk
Highly sensitive fluxgate magnetic field sensors with rod-shaped cores are widely used for non-destructive testing as well as for industrial applications. However, in case of both Foerster and Vacquier (two-core sensors configurations), fluxgate sensors sensitivity is directly connected with the relative magnetic permeability of the sensor’s core. It should be highlighted that the magnetic permeability of rod-shaped magnetic cores is driven mainly by the demagnetization factor determined by its slenderness (aspect ratio). The paper presents the analyses of sensitivity limits of fluxgate sensors with rod-shaped cores. On the base of estimations of demagnetization factor specific for fluxgate sensors, it is shown that in case of rod-shaped cores, the sensor’s sensitivity is connected with the shape of the core rather than its relative magnetic permeability. This conclusion is essential during the development and optimization of functional characteristics of fluxgate sensors.
{"title":"Sensitivity Limits and Functional Characteristics of Fluxgate Sensors with Rod-Shaped Magnetic Cores","authors":"Dominika Kopala, Anna Ostaszewska-Liżewska, R. Szewczyk","doi":"10.14313/par_244/29","DOIUrl":"https://doi.org/10.14313/par_244/29","url":null,"abstract":"Highly sensitive fluxgate magnetic field sensors with rod-shaped cores are widely used for non-destructive testing as well as for industrial applications. However, in case of both Foerster and Vacquier (two-core sensors configurations), fluxgate sensors sensitivity is directly connected with the relative magnetic permeability of the sensor’s core. It should be highlighted that the magnetic permeability of rod-shaped magnetic cores is driven mainly by the demagnetization factor determined by its slenderness (aspect ratio). The paper presents the analyses of sensitivity limits of fluxgate sensors with rod-shaped cores. On the base of estimations of demagnetization factor specific for fluxgate sensors, it is shown that in case of rod-shaped cores, the sensor’s sensitivity is connected with the shape of the core rather than its relative magnetic permeability. This conclusion is essential during the development and optimization of functional characteristics of fluxgate sensors.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130462999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, tracking systems have been significantly developed. A number of their possible applications have also increased. Their usage was no longer limited to the industrial applications and became more accessible to the everyday appliances. This article covers process of a design and synthesis of a ball stabilization system on a mobile platform. The mechanics and electronics of the platform have been described as well as a mathematical model of the platform and a process of a platform software development. Results of conducted tests of performance quality for step response, square and circle trajectories have been presented.
{"title":"The Stabilization System of a Ball on Mobile Platform","authors":"Michał Banach, R. Piotrowski","doi":"10.14313/par_243/11","DOIUrl":"https://doi.org/10.14313/par_243/11","url":null,"abstract":"In recent years, tracking systems have been significantly developed. A number of their possible applications have also increased. Their usage was no longer limited to the industrial applications and became more accessible to the everyday appliances. This article covers process of a design and synthesis of a ball stabilization system on a mobile platform. The mechanics and electronics of the platform have been described as well as a mathematical model of the platform and a process of a platform software development. Results of conducted tests of performance quality for step response, square and circle trajectories have been presented.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125396741","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 article presents two modular radio transmission jamming devices developed by the consortium of Łukasiewicz-PIAP and ITTI sp. z o.o. as part of the project: „Jamming of radio transmission in selected facilities of the Border Guard”. In typical operating conditions the devices ensure effective blocking of radio communication (prevention of information leakage, protection against remote radio detonation of IED) and analysis of the frequency spectrum in the 25 MHz to 5.9 GHz band. Developed jammers are intended for use by professional state services, have a modern user interface and offer the possibility of remote control. The most important parameters and functionalities are characterized, as well as the distinguishing non-standard operating modes are discussed, i.e. the spectrum analysis mode and the responsive jamming mode, which minimizes the negative effects of user’s exposure to electromagnetic radiation in the vicinity of working devices for a long time.
本文介绍了Łukasiewicz-PIAP和ITTI sp. z . o.o.联合开发的两种模块化无线电传输干扰装置，作为“干扰边境警卫选定设施的无线电传输”项目的一部分。在典型的操作条件下，这些设备可确保有效地阻断无线电通信(防止信息泄露，防止IED的远程无线电引爆)并分析25 MHz至5.9 GHz频段的频谱。开发的干扰机旨在供专业国家服务机构使用，具有现代化的用户界面，并提供远程控制的可能性。介绍了其最重要的参数和功能，并讨论了区分非标准工作模式，即频谱分析模式和响应式干扰模式，以最大限度地减少用户长时间暴露在工作设备附近的电磁辐射的负面影响。
{"title":"Implementation of ZKR-1 Wireless Communication Jammer. Presentation of the Results of Research and Development Projects","authors":"K. Bożek","doi":"10.14313/par_243/41","DOIUrl":"https://doi.org/10.14313/par_243/41","url":null,"abstract":"The article presents two modular radio transmission jamming devices developed by the consortium of Łukasiewicz-PIAP and ITTI sp. z o.o. as part of the project: „Jamming of radio transmission in selected facilities of the Border Guard”. In typical operating conditions the devices ensure effective blocking of radio communication (prevention of information leakage, protection against remote radio detonation of IED) and analysis of the frequency spectrum in the 25 MHz to 5.9 GHz band. Developed jammers are intended for use by professional state services, have a modern user interface and offer the possibility of remote control. The most important parameters and functionalities are characterized, as well as the distinguishing non-standard operating modes are discussed, i.e. the spectrum analysis mode and the responsive jamming mode, which minimizes the negative effects of user’s exposure to electromagnetic radiation in the vicinity of working devices for a long time.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132891568","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 transition of automated machine systems towards autonomous operation is progressing fast in various industrial sectors. The following paper presents the current situation in the regulations that normalize and support the development of working machines for construction purposes. A review of the existing ISO and IEC standards alongside own work focusing on autonomous machines, as well as a review of different activities in international industry groups regarding automation and autonomy of machines have been presented. Three different approaches to the concept of safety have been identified for different working conditions. The paper also tackles issues of on-board machine communication. By analysing different systems and their basic requirements, several optimization possibilities have been identified in relation to combining different data sources. It has been shown that the combination of different systems at the machine level as well as the connection between different machines can have a major impact on the performance of both the entire system as well as on the machine itself.
{"title":"Safety in the Use of Unmanned Working Machines","authors":"A. Typiak, R. Typiak","doi":"10.14313/par_243/47","DOIUrl":"https://doi.org/10.14313/par_243/47","url":null,"abstract":"The transition of automated machine systems towards autonomous operation is progressing fast in various industrial sectors. The following paper presents the current situation in the regulations that normalize and support the development of working machines for construction purposes. A review of the existing ISO and IEC standards alongside own work focusing on autonomous machines, as well as a review of different activities in international industry groups regarding automation and autonomy of machines have been presented. Three different approaches to the concept of safety have been identified for different working conditions. The paper also tackles issues of on-board machine communication. By analysing different systems and their basic requirements, several optimization possibilities have been identified in relation to combining different data sources. It has been shown that the combination of different systems at the machine level as well as the connection between different machines can have a major impact on the performance of both the entire system as well as on the machine itself.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"166 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114248086","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 method for selection of discretization step and discrete PID controller settings is presented for a model of servo with voltage controlled motor, described by an integrator with time constant. The method assumes a triple pole location of the closed-loop system to provide smooth control transients. Settling time is a design data. Influence of filtering degree in controller derivative component on reduction of discretization step is examined. Extended design problem with the filtering degree being an additional requirement is also considered.
{"title":"Discretization Step and PID Settings for Voltage Controlled Discrete Servo","authors":"A. Bozek, L. Trybus","doi":"10.14313/par_243/5","DOIUrl":"https://doi.org/10.14313/par_243/5","url":null,"abstract":"A method for selection of discretization step and discrete PID controller settings is presented for a model of servo with voltage controlled motor, described by an integrator with time constant. The method assumes a triple pole location of the closed-loop system to provide smooth control transients. Settling time is a design data. Influence of filtering degree in controller derivative component on reduction of discretization step is examined. Extended design problem with the filtering degree being an additional requirement is also considered.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121652308","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 construction of mobile robot manipulators for special applications must be optimized to achieve the required working capacity while maintaining a low mass. In the literature on the optimization of manipulator structures, the authors most often take into account the most unfavorable load case in their calculations or take into account several distinguished load cases resulting from the static or dynamic of the loaded manipulator. To optimize the design of a teleoperated robot manipulator, which during operation is exposed to contact with obstacles in an unstructured environment, the load analysis must be carried out in many aspects. The results of such analysis are used to select manipulator elements, e.g. drives, and to determine the loads for the design of the load-bearing structure and its optimization. The determined loads can be used to perform topological optimization of components of manipulators to minimize the mass while maintaining strength adapted to the operating conditions. Preliminary work on the preparation of a method for selecting such loads is presented.
{"title":"Selection of Loads in the Design and Optimization of Manipulators of Portable Mobile Robots for Special Applications","authors":"Tomasz Krakówka, A. Typiak","doi":"10.14313/par_243/61","DOIUrl":"https://doi.org/10.14313/par_243/61","url":null,"abstract":"The construction of mobile robot manipulators for special applications must be optimized to achieve the required working capacity while maintaining a low mass. In the literature on the optimization of manipulator structures, the authors most often take into account the most unfavorable load case in their calculations or take into account several distinguished load cases resulting from the static or dynamic of the loaded manipulator. To optimize the design of a teleoperated robot manipulator, which during operation is exposed to contact with obstacles in an unstructured environment, the load analysis must be carried out in many aspects. The results of such analysis are used to select manipulator elements, e.g. drives, and to determine the loads for the design of the load-bearing structure and its optimization. The determined loads can be used to perform topological optimization of components of manipulators to minimize the mass while maintaining strength adapted to the operating conditions. Preliminary work on the preparation of a method for selecting such loads is presented.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"310 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128009552","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 article presents the results of research on the handling of data types from the PN-EN 61131-3 standard in systems with ARM architecture. The tests were carried out on several different hardware platforms with the Cortex-M and Cortex-A series as CPUs. The research was carried out on the basis of the CPDev environment for creating and running control software. Due to the limitations of the ARM architecture, three methods of access to memory have been developed, and the results allow to determine the most effective. The article also presents the proposed virtual machine extension with new instructions to make data operations in ARM solutions more efficient.
{"title":"Support for PN-EN 61131-3 Standard Data Types in ARM Architecture with Memory Access Restrictions","authors":"Marcin Hubacz, Jan Sadolewski, B. Trybus","doi":"10.14313/par_243/23","DOIUrl":"https://doi.org/10.14313/par_243/23","url":null,"abstract":"The article presents the results of research on the handling of data types from the PN-EN 61131-3 standard in systems with ARM architecture. The tests were carried out on several different hardware platforms with the Cortex-M and Cortex-A series as CPUs. The research was carried out on the basis of the CPDev environment for creating and running control software. Due to the limitations of the ARM architecture, three methods of access to memory have been developed, and the results allow to determine the most effective. The article also presents the proposed virtual machine extension with new instructions to make data operations in ARM solutions more efficient.","PeriodicalId":383231,"journal":{"name":"Pomiary Automatyka Robotyka","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114234250","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：