Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to thei...Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to their high settings of the action value when a high-impedance grounding fault occurs.In this study,the relationship between the zero-sequence currents of each feeder and the neutral branch was analyzed.Then,a grounding protection method was proposed on the basis of the zero-sequence current ratio coefficient.It is defined as the ratio of the zero-sequence current of the feeder to that of the neutral branch.Nonetheless,both zero-sequence voltage and zero-sequence current are affected by the transition resistance,The influence of transition resistance can be eliminated by calculating this coefficient.Therefore,a method based on the zero-sequence current ratio coefficient was proposed considering the significant difference between the faulty feeder and healthy feeder.Furthermore,unbalanced current can be prevented by setting the starting current.PSCAD simulation results reveal that the proposed method shows high reliability and sensitivity when a high-resistance grounding fault occurs.展开更多
The authors give the solution to the problem of one-dimensional conso l idation of double-layered ground with the use of the differential quadrature me t hod. Case studies showed that the computational results for por...The authors give the solution to the problem of one-dimensional conso l idation of double-layered ground with the use of the differential quadrature me t hod. Case studies showed that the computational results for pore-water pressure in soil layer agreed with those of analytical solution; and that in the computat ional results for the interface of soil layer also agreed with those of the anal ytical solution except for the small discrepancies during shortly after the star t of computation. The advantages of the solution presented in this paper are tha t compared with the analytical solution, it avoids the cumbersome work in solvin g the transcendental equation for eigenvalues, and in the case of the Laplace transform s olution, it can resolve the precision problem in the numerical solution of long time inverse Laplace transform. Because of the matrix form of the solution in th is paper, it is convenient for formulating computational program for engineering practice. The formulas for calculating double-layered ground consolidation may be easily extended to the case of multi-layered soils.展开更多
The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR ground...The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm.If the fault disappears before LR is put into the system,it is judged as an instantaneous fault;while the fault does not disappear after LR is put into the system,it is judged as a permanent fault;the single-phase grounding fault(SLG)protection criterion based on zerosequence power variation is proposed to identify the instantaneous-permanent fault.Firstly,the distribution characteristic of zero-sequence voltage(ZSV)and zero-sequence current(ZSC)are analyzed after SLGfault occurs in multi-mode grounding.Then,according to the characteristics that zero-sequence power variation of non-fault collector line is small,while the zero-sequence power variation of fault collector line can reflect the active power component of fault resistance,the protection criterion based on zero-sequence power variation is constructed.The theoretical analysis and simulation results show that the protection criterion can distinguish the property of fault only by using the single terminal information,which has high reliability.展开更多
In this paper, the authors investigate the zeros and growth of solutions of second order linear differential equations with entire coefficients of [p, q]-order and obtain some results which improve and generalize some...In this paper, the authors investigate the zeros and growth of solutions of second order linear differential equations with entire coefficients of [p, q]-order and obtain some results which improve and generalize some previous results.展开更多
This article is presenting data from a retrospective analysis of medical records and computed tomography (CT) scans of patients’ chests with coronavirus infection “COVID-19” who applied to the diagnostic center of ...This article is presenting data from a retrospective analysis of medical records and computed tomography (CT) scans of patients’ chests with coronavirus infection “COVID-19” who applied to the diagnostic center of URFA in Osh during the first wave of the pandemic in the Kyrgyz Republic, with a description of individual clinical cases and their differential diagnosis. Chest computed tomography is one of the main methods in visual diagnosis of pneumonia in COVID-19 in hospitalized patients, which allows determining signs, symptoms for effective treatment.展开更多
China has made significant strides in economic and social development since reform and opening up over the past four decades.This process has been influenced by the exceptional innovation and entrepreneurship of Chine...China has made significant strides in economic and social development since reform and opening up over the past four decades.This process has been influenced by the exceptional innovation and entrepreneurship of Chinese business leaders,as well as their profound sentiments of compassion for the world and their country.It is of great significance to foster and promote an entrepreneurial spirit with distinctive Chinese characteristics.Not only is such spirit essential to the high-quality development of enterprises and the economy,but it is also a critical impetus for achieving Chinese modernization.Nevertheless,there is still a paucity of adequate theoretical discourse on the cultural origins and entrepreneurial spirit of outstanding Chinese business leaders.This paper employs the classical grounded theory method to conduct a 10-year follow-up research on 11 representative entrepreneurs and their enterprises.The results indicate that these entrepreneurs exhibit an evolving worldview along the paths of“self-cultivation and moral conduct”,“assisting employees to achieve”,“multilateral symbiosis”,and“the oneness of existence”when interacting with themselves,employees,partners,the general public,and all things in nature.Such entrepreneurial spirit is embodied in this paper as the“Tianxia(all-under-heaven)worldview”.Through theoretical construction,this study defines the concept of“Tianxia worldview”and extensively examines the distinctions and connections between the broadminded“Tianxia worldview”and the kinship-centered“differential mode of association”in terms of internal structure,value orientation,and applicable groups.It is posited that the transition from the former to the latter is a continuous process of transcendence and evolution of the individual mindset.This study has theoretical significance in the context of advancing the research on the Chinese entrepreneurial spirit,transcending the constraints of the management approach based on the“differential mode of association”,and enhancing the research on social responsibility from the perspective of“benefit corporations”.It also has practical value in overcoming the trust dilemma and development impediment of family businesses,ensuring that enterprises consciously fulfill their social responsibilities in a broader social context,and achieving common prosperity and progress for both enterprises and society.展开更多
The texture of ground-based nephogram is abundant and multiplicity.Many cloud textures are not as clear as artificial textures.A nephogram enhancement algorithm based on Adaptive Fractional Differential is established...The texture of ground-based nephogram is abundant and multiplicity.Many cloud textures are not as clear as artificial textures.A nephogram enhancement algorithm based on Adaptive Fractional Differential is established to extract the natural texture of visible ground-based cloud image.Grunwald-Lentikov(G-L)and Grunwald-Lentikov(R-L)fractional differential operators are applied to the enhancement algorithm of ground-based nephogram.An operator mask based on adaptive differential order is designed.The corresponding mask template is used to process each pixel.The results show that this method can extract image texture and edge details and simplify the process of differential order selection.展开更多
Considering the joint effects of various factors such as temporal baseline, spatial baseline, thermal noise, the difference of Doppler centroid frequency and the error of data processing on the interference correlatio...Considering the joint effects of various factors such as temporal baseline, spatial baseline, thermal noise, the difference of Doppler centroid frequency and the error of data processing on the interference correlation, an optimum selection method of common master images for ground deformation monitoring based on the permanent scatterer and differential SAR interferometry （PS-DInSAR） technique is proposed, in which the joint correlation coeficient is used as the evaluation function. The principle and realization method of PS-DInSAR technology is introduced, the factors affecting the DInSAR correlation are analysed, and the joint correlation function model and its solution are presented. Finally an experiment for the optimum selection of common master images is performed by using 25 SAR images over Shanghai taken by the ERS-1/2 as test data. The results indicate that the optimum selection method for PS-DInSAR common master images is effective and reliable.展开更多
Considering gravity change from ground alignment to space applications, a fuzzy proportional-integral-differential(PID)control strategy is proposed to make the space manipulator track the desired trajectories in diffe...Considering gravity change from ground alignment to space applications, a fuzzy proportional-integral-differential(PID)control strategy is proposed to make the space manipulator track the desired trajectories in different gravity environments. The fuzzy PID controller is developed by combining the fuzzy approach with the PID control method, and the parameters of the PID controller can be adjusted on line based on the ability of the fuzzy controller. Simulations using the dynamic model of the space manipulator have shown the effectiveness of the algorithm in the trajectory tracking problem. Compared with the results of conventional PID control,the control performance of the fuzzy PID is more effective for manipulator trajectory control.展开更多
基金supported in part by National Key Research and Development Program of China(2016YFB0900603)Technology Projects of State Grid Corporation of China(52094017000W).
文摘Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to their high settings of the action value when a high-impedance grounding fault occurs.In this study,the relationship between the zero-sequence currents of each feeder and the neutral branch was analyzed.Then,a grounding protection method was proposed on the basis of the zero-sequence current ratio coefficient.It is defined as the ratio of the zero-sequence current of the feeder to that of the neutral branch.Nonetheless,both zero-sequence voltage and zero-sequence current are affected by the transition resistance,The influence of transition resistance can be eliminated by calculating this coefficient.Therefore,a method based on the zero-sequence current ratio coefficient was proposed considering the significant difference between the faulty feeder and healthy feeder.Furthermore,unbalanced current can be prevented by setting the starting current.PSCAD simulation results reveal that the proposed method shows high reliability and sensitivity when a high-resistance grounding fault occurs.
文摘The authors give the solution to the problem of one-dimensional conso l idation of double-layered ground with the use of the differential quadrature me t hod. Case studies showed that the computational results for pore-water pressure in soil layer agreed with those of analytical solution; and that in the computat ional results for the interface of soil layer also agreed with those of the anal ytical solution except for the small discrepancies during shortly after the star t of computation. The advantages of the solution presented in this paper are tha t compared with the analytical solution, it avoids the cumbersome work in solvin g the transcendental equation for eigenvalues, and in the case of the Laplace transform s olution, it can resolve the precision problem in the numerical solution of long time inverse Laplace transform. Because of the matrix form of the solution in th is paper, it is convenient for formulating computational program for engineering practice. The formulas for calculating double-layered ground consolidation may be easily extended to the case of multi-layered soils.
基金This paper is supported in part by the National Natural Science Foundations of China,and the Major Science and Technology Projects in Yunnan Province under Grant Nos.51667010,51807085,and 202002AF080001.
文摘The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm.If the fault disappears before LR is put into the system,it is judged as an instantaneous fault;while the fault does not disappear after LR is put into the system,it is judged as a permanent fault;the single-phase grounding fault(SLG)protection criterion based on zerosequence power variation is proposed to identify the instantaneous-permanent fault.Firstly,the distribution characteristic of zero-sequence voltage(ZSV)and zero-sequence current(ZSC)are analyzed after SLGfault occurs in multi-mode grounding.Then,according to the characteristics that zero-sequence power variation of non-fault collector line is small,while the zero-sequence power variation of fault collector line can reflect the active power component of fault resistance,the protection criterion based on zero-sequence power variation is constructed.The theoretical analysis and simulation results show that the protection criterion can distinguish the property of fault only by using the single terminal information,which has high reliability.
基金Supported by the Natural Science Foundation of Jiangxi Province(Grant Nos.20132BAB21100220122BAB211005)+1 种基金the Youth Foundation of Education Bureau of Jiangxi Province(Grant Nos.GJJ14271GJJ14272)
文摘In this paper, the authors investigate the zeros and growth of solutions of second order linear differential equations with entire coefficients of [p, q]-order and obtain some results which improve and generalize some previous results.
文摘This article is presenting data from a retrospective analysis of medical records and computed tomography (CT) scans of patients’ chests with coronavirus infection “COVID-19” who applied to the diagnostic center of URFA in Osh during the first wave of the pandemic in the Kyrgyz Republic, with a description of individual clinical cases and their differential diagnosis. Chest computed tomography is one of the main methods in visual diagnosis of pneumonia in COVID-19 in hospitalized patients, which allows determining signs, symptoms for effective treatment.
基金a result of the Major Project of Marxist Theory Research and Construction in 2023 and Major Project of the National Social Science Fund of China(NSSFC)“Research on Education,Science and Technology,and Talent as Fundamental Strategic Support for the Comprehensive Construction of a Modern Socialist Country”(Grant No.2023MZD010)General Project of the National Natural Science Foundation of China(NSFC)“The Tianxia Worldview of Contemporary Chinese Entrepreneurs:Concept Proposal,Scale Design,and Efficacy Verification”(Grant No.72072061)2020 Guangzhou Philosophy and Social Science Planning Project“Research on the Social Network and Development Mechanism of Enterprise-Driven Traditional Culture Revival in the Guangdong-Hong Kong-Macao Greater Bay Area”(Grant No.2020GZYB19).
文摘China has made significant strides in economic and social development since reform and opening up over the past four decades.This process has been influenced by the exceptional innovation and entrepreneurship of Chinese business leaders,as well as their profound sentiments of compassion for the world and their country.It is of great significance to foster and promote an entrepreneurial spirit with distinctive Chinese characteristics.Not only is such spirit essential to the high-quality development of enterprises and the economy,but it is also a critical impetus for achieving Chinese modernization.Nevertheless,there is still a paucity of adequate theoretical discourse on the cultural origins and entrepreneurial spirit of outstanding Chinese business leaders.This paper employs the classical grounded theory method to conduct a 10-year follow-up research on 11 representative entrepreneurs and their enterprises.The results indicate that these entrepreneurs exhibit an evolving worldview along the paths of“self-cultivation and moral conduct”,“assisting employees to achieve”,“multilateral symbiosis”,and“the oneness of existence”when interacting with themselves,employees,partners,the general public,and all things in nature.Such entrepreneurial spirit is embodied in this paper as the“Tianxia(all-under-heaven)worldview”.Through theoretical construction,this study defines the concept of“Tianxia worldview”and extensively examines the distinctions and connections between the broadminded“Tianxia worldview”and the kinship-centered“differential mode of association”in terms of internal structure,value orientation,and applicable groups.It is posited that the transition from the former to the latter is a continuous process of transcendence and evolution of the individual mindset.This study has theoretical significance in the context of advancing the research on the Chinese entrepreneurial spirit,transcending the constraints of the management approach based on the“differential mode of association”,and enhancing the research on social responsibility from the perspective of“benefit corporations”.It also has practical value in overcoming the trust dilemma and development impediment of family businesses,ensuring that enterprises consciously fulfill their social responsibilities in a broader social context,and achieving common prosperity and progress for both enterprises and society.
基金This work is supported by the National Natural Science Foundation of China(Grant No.41775165)Guangxi Key Laboratory of Automatic Detecting Technology and Instruments(YQ21207)the Qinglan Project of Jiangsu Province.
文摘The texture of ground-based nephogram is abundant and multiplicity.Many cloud textures are not as clear as artificial textures.A nephogram enhancement algorithm based on Adaptive Fractional Differential is established to extract the natural texture of visible ground-based cloud image.Grunwald-Lentikov(G-L)and Grunwald-Lentikov(R-L)fractional differential operators are applied to the enhancement algorithm of ground-based nephogram.An operator mask based on adaptive differential order is designed.The corresponding mask template is used to process each pixel.The results show that this method can extract image texture and edge details and simplify the process of differential order selection.
文摘Considering the joint effects of various factors such as temporal baseline, spatial baseline, thermal noise, the difference of Doppler centroid frequency and the error of data processing on the interference correlation, an optimum selection method of common master images for ground deformation monitoring based on the permanent scatterer and differential SAR interferometry （PS-DInSAR） technique is proposed, in which the joint correlation coeficient is used as the evaluation function. The principle and realization method of PS-DInSAR technology is introduced, the factors affecting the DInSAR correlation are analysed, and the joint correlation function model and its solution are presented. Finally an experiment for the optimum selection of common master images is performed by using 25 SAR images over Shanghai taken by the ERS-1/2 as test data. The results indicate that the optimum selection method for PS-DInSAR common master images is effective and reliable.
基金supported by National High Technology Research and Development Program of China(863 Program)(No.2011AA)
文摘Considering gravity change from ground alignment to space applications, a fuzzy proportional-integral-differential(PID)control strategy is proposed to make the space manipulator track the desired trajectories in different gravity environments. The fuzzy PID controller is developed by combining the fuzzy approach with the PID control method, and the parameters of the PID controller can be adjusted on line based on the ability of the fuzzy controller. Simulations using the dynamic model of the space manipulator have shown the effectiveness of the algorithm in the trajectory tracking problem. Compared with the results of conventional PID control,the control performance of the fuzzy PID is more effective for manipulator trajectory control.
