Abstract The paper determines a non-classical Bittner operational calculus model, in which the derivative is understood as an -symmetric difference Dm,n{x (k)} := {x (k+m)− x (k− n). By considering an operation Dm,n,b{x (k)} := {x (k+m)− b (k)x (k− n), the formulated model has been generalized.
本文确定了一个非经典Bittner运算模型，其导数被理解为一个-对称差分Dm,n{x (k)}:= {x (k+m) - x (k−n)。通过考虑一个运算Dm,n,b{x (k)}:= {x (k+m) - b (k)x (k−n)，推广了该模型。
{"title":"An Operational Calculus Model with the (m,n) - Symmetric Difference","authors":"H. Wysocki","doi":"10.2478/sjpna-2020-0016","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0016","url":null,"abstract":"Abstract The paper determines a non-classical Bittner operational calculus model, in which the derivative is understood as an -symmetric difference Dm,n{x (k)} := {x (k+m)− x (k− n). By considering an operation Dm,n,b{x (k)} := {x (k+m)− b (k)x (k− n), the formulated model has been generalized.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"223 1","pages":"67 - 82"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45688997","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}
Abstract The article is a presentation, and detailed description of a mobile, vehicular robot whose task is to support the alarm sub-unit. The project was created in response to the increasing need for monitoring, and recognition of the areas. The robot’s interface was created with the use of integrated development environments for Python. The software implementation was possible due to a minicomputer Raspberry Pi 4 B. The robot’s frame is made out of components which are based on the main chassis. The robot is equipped with compatible sensors and cameras. Those, combined with the interface, are able to give a real-time preview of the area in which the robot is in. This particular vehicular robot is designed to eliminate the risks caused by tasks of alarm sub-unit, by giving the real-time preview, and analysis of the currently watched area. In addition, it can be used to inspect soldiers in the containment zones, and to help with the identification of unknown objects.
摘要:本文介绍并详细描述了一种以支持报警子单元为任务的移动车载机器人。该项目是为了响应日益增长的监测需求和对这些地区的认识而创建的。机器人的界面是使用Python的集成开发环境创建的。由于一台小型计算机Raspberry Pi 4b，软件实现成为可能。机器人的框架由基于主机箱的组件组成。该机器人配备了兼容的传感器和摄像头。这些与界面相结合，能够实时预览机器人所处的区域。这种特殊的车载机器人通过对当前监视区域进行实时预览和分析，消除了报警子单元任务带来的风险。此外，它还可以用来检查隔离区的士兵，并帮助识别未知物体。
{"title":"Mobile Wheeled Robot to Support the Task of the Alarm Sub - Unit","authors":"Daniel Powarzyński","doi":"10.2478/sjpna-2020-0015","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0015","url":null,"abstract":"Abstract The article is a presentation, and detailed description of a mobile, vehicular robot whose task is to support the alarm sub-unit. The project was created in response to the increasing need for monitoring, and recognition of the areas. The robot’s interface was created with the use of integrated development environments for Python. The software implementation was possible due to a minicomputer Raspberry Pi 4 B. The robot’s frame is made out of components which are based on the main chassis. The robot is equipped with compatible sensors and cameras. Those, combined with the interface, are able to give a real-time preview of the area in which the robot is in. This particular vehicular robot is designed to eliminate the risks caused by tasks of alarm sub-unit, by giving the real-time preview, and analysis of the currently watched area. In addition, it can be used to inspect soldiers in the containment zones, and to help with the identification of unknown objects.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"223 1","pages":"53 - 66"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46739619","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}
Abstract Tracking of small objects in any given airspace is an integral part of modern security systems. In these systems, there are embedded methods that employ the techniques based on either radio waves, or acoustic signals, or light radiation. The computer vision operation, springing from the light radiation-based technique, has prompted interest in its research. This operation has the advantage of being less expensive than radars and acoustic systems. In addition, it can solve complex security problems by detecting and tracking humans, vehicles, and flying objects. Therefore, this article evaluates the usefulness of the varying computer vision algorithms for tracking of small flying objects.
{"title":"Tracking of Unmanned Aerial Vehicles Using Computer Vision Methods: A Comparative Analysis","authors":"Stanisław Hożyń, Miłosz Wierszyło","doi":"10.2478/sjpna-2020-0014","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0014","url":null,"abstract":"Abstract Tracking of small objects in any given airspace is an integral part of modern security systems. In these systems, there are embedded methods that employ the techniques based on either radio waves, or acoustic signals, or light radiation. The computer vision operation, springing from the light radiation-based technique, has prompted interest in its research. This operation has the advantage of being less expensive than radars and acoustic systems. In addition, it can solve complex security problems by detecting and tracking humans, vehicles, and flying objects. Therefore, this article evaluates the usefulness of the varying computer vision algorithms for tracking of small flying objects.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"223 1","pages":"39 - 51"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46567415","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}
Abstract The Doppler effect in 2×2, 3×3, 4×4 MIMO wireless communication systems with channel estimation is studied. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting, along with the eight alternative orthogonal sets similar to the Walsh set. MIMO transmissions are simulated for 10 cases of the frame length and pilot symbols per frame by no Doppler shift to 1100 Hz Doppler shift with a step of 100 Hz. Based on the simulation, it is ascertained that MIMO transmissions of shorter frames are less sensitive to the Doppler effect. Despite increasing the number of antennas does not mitigate the Doppler effect, and the bit-error rate performance of 4×4 MIMO systems worsens faster than that of 2×2 MIMO systems, it is better to use the maximum number of antennas. The Doppler effect does badly worsen the performance at highway and express train speeds (100 km/hr, and faster), leaving only possibility to further shorten transmissions. This, however, decreases the data rate, but the respective accuracy-versus-data-rate tradeoff must be acceptable.
{"title":"Doppler Effect in 2 × 2 to 4 × 4 Mimo Systems of Wireless Communication with Orthogonal Pilot Channel Estimation","authors":"V. Romanuke","doi":"10.2478/sjpna-2020-0012","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0012","url":null,"abstract":"Abstract The Doppler effect in 2×2, 3×3, 4×4 MIMO wireless communication systems with channel estimation is studied. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting, along with the eight alternative orthogonal sets similar to the Walsh set. MIMO transmissions are simulated for 10 cases of the frame length and pilot symbols per frame by no Doppler shift to 1100 Hz Doppler shift with a step of 100 Hz. Based on the simulation, it is ascertained that MIMO transmissions of shorter frames are less sensitive to the Doppler effect. Despite increasing the number of antennas does not mitigate the Doppler effect, and the bit-error rate performance of 4×4 MIMO systems worsens faster than that of 2×2 MIMO systems, it is better to use the maximum number of antennas. The Doppler effect does badly worsen the performance at highway and express train speeds (100 km/hr, and faster), leaving only possibility to further shorten transmissions. This, however, decreases the data rate, but the respective accuracy-versus-data-rate tradeoff must be acceptable.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"223 1","pages":"5 - 20"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49649029","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}
Abstract The paper presents dynamical models of controlling voltage and frequency of ship’s electric supply set. The simulation model of synchronous generator, implemented in Matlab/Simulink, was described. For the developed simulation model, developed control systems using fuzzy controllers type P and PD were presented. Simulation research for resistance, inductive and capacitive loads were carried out for these regulators. Sample results of simulation tests are presented in the form of voltage waveforms at the output of the generator and rotational speed of the internal combustion engine for various load conditions. The conducted tests allow to assess the quality of the control process using fuzzy controllers and thus ensure the selection of the optimal solution.
{"title":"Controlling the Operation of a Ship’s Electric Power Supply Using Fuzzy Controllers","authors":"B. Żak, Stanisław Hożyń","doi":"10.2478/sjpna-2020-0007","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0007","url":null,"abstract":"Abstract The paper presents dynamical models of controlling voltage and frequency of ship’s electric supply set. The simulation model of synchronous generator, implemented in Matlab/Simulink, was described. For the developed simulation model, developed control systems using fuzzy controllers type P and PD were presented. Simulation research for resistance, inductive and capacitive loads were carried out for these regulators. Sample results of simulation tests are presented in the form of voltage waveforms at the output of the generator and rotational speed of the internal combustion engine for various load conditions. The conducted tests allow to assess the quality of the control process using fuzzy controllers and thus ensure the selection of the optimal solution.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"222 1","pages":"1 - 13"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42549550","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}
Abstract The stochastic processes theory provides concepts, and theorems, which allow to build the probabilistic models concerning accidents. “Counting process” can be applied for modelling the number of road, sea, and railway accidents in the given time intervals. A crucial role in construction of the models plays a Poisson process and its generalizations. The nonhomogeneous Poisson process, and the corresponding nonhomogeneous compound Poisson process are applied for modelling the road accidents number, and number of people injured and killed in Polish roads. To estimate model parameters were used data coming from the annual reports of the Polish police.
{"title":"Nonhomogeneus Generalisations of Poisson Process in the Modeling of Random Processes Related to Road Accidents","authors":"F. Grabski","doi":"10.2478/sjpna-2020-0009","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0009","url":null,"abstract":"Abstract The stochastic processes theory provides concepts, and theorems, which allow to build the probabilistic models concerning accidents. “Counting process” can be applied for modelling the number of road, sea, and railway accidents in the given time intervals. A crucial role in construction of the models plays a Poisson process and its generalizations. The nonhomogeneous Poisson process, and the corresponding nonhomogeneous compound Poisson process are applied for modelling the road accidents number, and number of people injured and killed in Polish roads. To estimate model parameters were used data coming from the annual reports of the Polish police.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"222 1","pages":"29 - 42"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46404741","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}
Abstract The paper presents results of research based on analysis of historical and present studies of the Arctic ice drift. Current information about Arctic ice drift comes from the scientific expedition organized by the Alfred-Wrgener-Institut Helmholtz Centre for Polar and Marine Research (AWI) from Bremerhaven (Germany) in the Arctic Ocean, as a part of the Multidiscipli-nary drifting Observatory for the Study of Arctic Climate (MOSAiC), coming from the deck of the icebreaker RV “Polarstern”. The main purpose of the article was to collect and illustrate information on the phenomenon of ice drift in the Arctic Ocean, considering data from ongoing research during the MOSAiC expedition. The average movement speed of the icebreaker RV “Polarstern” frozen in Arctic ice during the first three legs of the expedition was over 5 Nm/day, which is characteristic of the current data relating to the speed of the Arctic ice drift in the place of research. On the other hand, the article is popular science, and presents the overall characteristics of Arctic ice drift with an indication of the general directions, and speed of its movement. Ice drift speeds in the Arctic can reach exceptionally high values under favorable conditions. The drift of sea ice reaching at its intensity/intensity values close to the limit (dangerous criterion) in these extreme cases is called the “ice river”. The speed of “ice rivers” can reach up to 1–2 knots, however, in extreme conditions up to 9 knots. Based on data from the AWI, correlation points were identified between the speed of Arctic ice drift and the speed of winds and atmospheric pressure values.
{"title":"Ice Drift in the Arctic Ocean","authors":"C. Dyrcz","doi":"10.2478/sjpna-2020-0011","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0011","url":null,"abstract":"Abstract The paper presents results of research based on analysis of historical and present studies of the Arctic ice drift. Current information about Arctic ice drift comes from the scientific expedition organized by the Alfred-Wrgener-Institut Helmholtz Centre for Polar and Marine Research (AWI) from Bremerhaven (Germany) in the Arctic Ocean, as a part of the Multidiscipli-nary drifting Observatory for the Study of Arctic Climate (MOSAiC), coming from the deck of the icebreaker RV “Polarstern”. The main purpose of the article was to collect and illustrate information on the phenomenon of ice drift in the Arctic Ocean, considering data from ongoing research during the MOSAiC expedition. The average movement speed of the icebreaker RV “Polarstern” frozen in Arctic ice during the first three legs of the expedition was over 5 Nm/day, which is characteristic of the current data relating to the speed of the Arctic ice drift in the place of research. On the other hand, the article is popular science, and presents the overall characteristics of Arctic ice drift with an indication of the general directions, and speed of its movement. Ice drift speeds in the Arctic can reach exceptionally high values under favorable conditions. The drift of sea ice reaching at its intensity/intensity values close to the limit (dangerous criterion) in these extreme cases is called the “ice river”. The speed of “ice rivers” can reach up to 1–2 knots, however, in extreme conditions up to 9 knots. Based on data from the AWI, correlation points were identified between the speed of Arctic ice drift and the speed of winds and atmospheric pressure values.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"222 1","pages":"68 - 85"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47201209","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}
Abstract The article presents modeling research on the M/S “Ziemia Zamojska” reduced model, carried out in an open fresh water area by a team of employees of the Department of Operating of Floating Vessels, Polish Naval Academy, Gdynia. The research involved circulating the model with constant angle of heel on the selected side, and the main engine set to full speed ahead. Using a real ship to carry this type of investigations is risky. It may lead to some failures like e.g. rudder failure, steering gear malfunction, overload and in some circumstances even main engine seizure. For this reason, ships are not tested with the rudder put to starboard or to port at the full speed ahead setting, even during a “Crash Stop” maneuver. However, based on the analysis of accidents at sea, and practical experience, it appears that during real operating conditions of vessels, there may occur situations when, for the sake of safety, the maneuver mentioned above must be carried out. Therefore, the authors had to conduct model tests of a floating vessel for the described case of ship operation
{"title":"The Effect on Constant Heel on Circulation of a Vessel Calculated on the Basis of Investigations of M/S “Ziemia Zamojska” Model","authors":"W. Mironiuk, A. Panasiuk, M. Szymoński","doi":"10.2478/sjpna-2020-0008","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0008","url":null,"abstract":"Abstract The article presents modeling research on the M/S “Ziemia Zamojska” reduced model, carried out in an open fresh water area by a team of employees of the Department of Operating of Floating Vessels, Polish Naval Academy, Gdynia. The research involved circulating the model with constant angle of heel on the selected side, and the main engine set to full speed ahead. Using a real ship to carry this type of investigations is risky. It may lead to some failures like e.g. rudder failure, steering gear malfunction, overload and in some circumstances even main engine seizure. For this reason, ships are not tested with the rudder put to starboard or to port at the full speed ahead setting, even during a “Crash Stop” maneuver. However, based on the analysis of accidents at sea, and practical experience, it appears that during real operating conditions of vessels, there may occur situations when, for the sake of safety, the maneuver mentioned above must be carried out. Therefore, the authors had to conduct model tests of a floating vessel for the described case of ship operation","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"222 1","pages":"14 - 28"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46946744","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}
Abstract A 2×2 MIMO wireless communication system with channel estimation is simulated, in which two transmit, and two receive antennas are employed. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting. Data are modulated by coherent binary phase-shift keying, whereupon an orthogonal space-time block coding subsystem encodes information symbols by using the Alamouti code. Based on the simulation, it is ascertained a possibility to decrease the bit-error rate by substituting the Hadamard sequences for the sequences having irregular structures, and constituting the eight known orthogonal bases. Considering a de-orthogonalization caused by two any pilot sequence symbol errors, the bit-error rate is decreased by almost 2.9 %. If de-orthogonalizations are caused by two repeated indefinite, and definite pilot sequence symbol errors, the decrements are almost 16 % and 10 %, respectively. Whichever sequences are used for piloting, the 2×2 MIMO system is ascertained to be resistant to the de-orthogonalization if the frame is of 128 to 256 symbols piloted with 32 to 64 symbols, respectively.
{"title":"Pilot Symbol Error Re - Orthogonalization in 2 × 2 MIMO Systems of Wireless Communication","authors":"V. Romanuke","doi":"10.2478/sjpna-2020-0010","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0010","url":null,"abstract":"Abstract A 2×2 MIMO wireless communication system with channel estimation is simulated, in which two transmit, and two receive antennas are employed. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting. Data are modulated by coherent binary phase-shift keying, whereupon an orthogonal space-time block coding subsystem encodes information symbols by using the Alamouti code. Based on the simulation, it is ascertained a possibility to decrease the bit-error rate by substituting the Hadamard sequences for the sequences having irregular structures, and constituting the eight known orthogonal bases. Considering a de-orthogonalization caused by two any pilot sequence symbol errors, the bit-error rate is decreased by almost 2.9 %. If de-orthogonalizations are caused by two repeated indefinite, and definite pilot sequence symbol errors, the decrements are almost 16 % and 10 %, respectively. Whichever sequences are used for piloting, the 2×2 MIMO system is ascertained to be resistant to the de-orthogonalization if the frame is of 128 to 256 symbols piloted with 32 to 64 symbols, respectively.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"222 1","pages":"43 - 67"},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42709520","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}
Abstract This article contains a description of the implemented STANTOS™ Integrated Platform Management System (IPMS) laboratory created by Research and Development Center Maritime Technology Center for the Polish Naval Academy in Gdynia. The author briefly described the topology of the solution, justifies the choice of hardware and software solutions. Concept of use was written, where the usefulness of the implemented laboratory was motivated, with a focus on cases where safety plays a key role.
{"title":"Modern Integrated Platform Management System Laboratory for Polish Naval Academy: Design and Implementation","authors":"Rafał Warżała","doi":"10.2478/sjpna-2020-0005","DOIUrl":"https://doi.org/10.2478/sjpna-2020-0005","url":null,"abstract":"Abstract This article contains a description of the implemented STANTOS™ Integrated Platform Management System (IPMS) laboratory created by Research and Development Center Maritime Technology Center for the Polish Naval Academy in Gdynia. The author briefly described the topology of the solution, justifies the choice of hardware and software solutions. Concept of use was written, where the usefulness of the implemented laboratory was motivated, with a focus on cases where safety plays a key role.","PeriodicalId":34248,"journal":{"name":"Scientific Journal of Polish Naval Academy","volume":"220-221 1","pages":"59 - 71"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47179327","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：