The index systems are not only the tools to evaluate existing practice results, but also the guides to the future development direction and development way of practical activities. ＂Well-off society＂ is a relatively...The index systems are not only the tools to evaluate existing practice results, but also the guides to the future development direction and development way of practical activities. ＂Well-off society＂ is a relatively vague concept, and the contents of it ceaselessly change with the advancement of society and the development of productivity. Now the construction of a well-off society in an all-round way enters a critical stage, so the original evaluation standards must change with gradual advancement of the construction goal of a well-off society. So it is very necessary for us to build a comprehensive evaluation index system and make it better and better to provide effective statistical consultation and statistical supervision for constructing a well-off society in an all-round way. This paper attempts to analyze the current evaluation index system, then puts forward the general thinking and flame work of the index system of building a well-off society in an all-round way.展开更多
In this paper, the attack detection problem is investigated for a class of closed-loop systems subjected to unknownbutbounded noises in the presence of stealthy attacks. The measurement outputs from the sensors are qu...In this paper, the attack detection problem is investigated for a class of closed-loop systems subjected to unknownbutbounded noises in the presence of stealthy attacks. The measurement outputs from the sensors are quantized before transmission.A specific type of perfect stealthy attack, which meets certain rather stringent conditions, is taken into account. Such attacks could be injected by adversaries into both the sensor-toestimator and controller-to-actuator channels, with the aim of disrupting the normal data flow. For the purpose of defending against these perfect stealthy attacks, a novel scheme based on watermarks is developed. This scheme includes the injection of watermarks(applied to data prior to quantization) and the recovery of data(implemented before the data reaches the estimator).The watermark-based scheme is designed to be both timevarying and hidden from adversaries through incorporating a time-varying and bounded watermark signal. Subsequently, a watermark-based attack detection strategy is proposed which thoroughly considers the characteristics of perfect stealthy attacks,thereby ensuring that an alarm is activated upon the occurrence of such attacks. An example is provided to demonstrate the efficacy of the proposed mechanism for detecting attacks.展开更多
The quantum state transmission through the medium of high-dimensional many-particle system （boson or spinless fermion） is generally studied with a symmetry analysis. We discover that, if the spectrum of a Hamiltonia...The quantum state transmission through the medium of high-dimensional many-particle system （boson or spinless fermion） is generally studied with a symmetry analysis. We discover that, if the spectrum of a Hamiltonian matches the symmetry of a fermion or boson system in a certain fashion, a perfect quantum state transfer can be implemented without any operation on the medium with pre-engineered nearest neighbor （NN）. We also study a simple but realistic near half-filled tight-bindlng fermion system wlth uniform NN hopping integral. We show that an arbitrary many-particle state near the fermi surface can be perfectly transferred to its translational counterpart.展开更多
Wireless medical sensor networks(WMSNs)play a significant role in increasing the availability of remote healthcare systems.The vital and physiological data of the patient can be collected using the WMSN via sensor nod...Wireless medical sensor networks(WMSNs)play a significant role in increasing the availability of remote healthcare systems.The vital and physiological data of the patient can be collected using the WMSN via sensor nodes that are placed on his/her body and then transmitted remotely to a healthcare professional for proper diagnosis.The protection of the patient’s privacy and their data from unauthorized access is a major concern in such systems.Therefore,an authentication scheme with a high level of security is one of the most effective mechanisms by which to address these security concerns.Many authentication schemes for remote patient monitoring have been proposed recently.However,the majority of these schemes are extremely vulnerable to attacks and are unsuitable for practical use.This paper proposes a secure three-factor authentication scheme for a patient-monitoring healthcare system that operates remotely using a WMSN.The proposed authentication scheme is formally verified using the Burrows,Abadi and Needham’s(BAN)logic model and an automatic cryptographic protocol verifier(ProVerif)tool.We show that our authentication scheme can prevent relevant types of security breaches in a practical context according to the discussed possible attack scenarios.Comparisons of the security and performance are carried out with recently proposed authentication schemes.The results of the analysis show that the proposed authentication scheme is secure and practical for use,with reasonable storage space,computation,and communication efficiency.展开更多
With the emergence of Internet of Things,modern control systems have to deal with the big data from the ubiquitous information sensing mobile devices,cameras,microphones,radio-frequency identification devices,wireless...With the emergence of Internet of Things,modern control systems have to deal with the big data from the ubiquitous information sensing mobile devices,cameras,microphones,radio-frequency identification devices,wireless sensor networks,etc.,which is often beyond the capacity of traditional control technologies.To deal with this issue,the rapidly developing cloud computing may provide a perfect platform for big data storage and processing,controller design,and performance optimization.Thereby,with the extension and application of the basic theory and method of cloud computing defined by software in the field of automatic control,cloud control systems have recently attracted much attention from both researchers and engineers.展开更多
With the emergence of Internet of Things,modern control systems have to deal with the big data from the ubiquitous information sensing mobile devices,cameras,microphones,radio-frequency identification devices,wireless...With the emergence of Internet of Things,modern control systems have to deal with the big data from the ubiquitous information sensing mobile devices,cameras,microphones,radio-frequency identification devices,wireless sensor networks,etc.,which is often beyond the capacity of traditional control technologies.To deal with this issue,the rapidly developing cloud computing may provide a perfect platform for big data storage and processing,controller design,and performance optimization.展开更多
Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perf...Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber（CPA）beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices.展开更多
The healthcare internet of things(IoT)system has dramatically reshaped this important industry sector.This system employs the latest technology of IoT and wireless medical sensor networks to support the reliable conne...The healthcare internet of things(IoT)system has dramatically reshaped this important industry sector.This system employs the latest technology of IoT and wireless medical sensor networks to support the reliable connection of patients and healthcare providers.The goal is the remote monitoring of a patient’s physiological data by physicians.Moreover,this system can reduce the number and expenses of healthcare centers,make up for the shortage of healthcare centers in remote areas,enable consultation with expert physicians around the world,and increase the health awareness of communities.The major challenges that affect the rapid deployment and widespread acceptance of such a system are the weaknesses in the authentication process,which should maintain the privacy of patients,and the integrity of remote medical instructions.Current research results indicate the need of a flexible authentication scheme.This study proposes a scheme with enhanced security for healthcare IoT systems,called an end-to-end authentication scheme for healthcare IoT systems,that is,an E2EA.The proposed scheme supports security services such as a strong and flexible authentication process,simultaneous anonymity of the patient and physician,and perfect forward secrecy services.A security analysis based on formal and informal methods demonstrates that the proposed scheme can resist numerous security-related attacks.A comparison with related authentication schemes shows that the proposed scheme is efficient in terms of communication,computation,and storage,and therefore cannot only offer attractive security services but can reasonably be applied to healthcare IoT systems.展开更多
Ultra WideBand (UWB) radio is a new wireless technology that transmits extremely short duration radio impulses. In this paper, a new synchronization scheme is proposed in Direct Sequence (DS) UWB system using Perfect ...Ultra WideBand (UWB) radio is a new wireless technology that transmits extremely short duration radio impulses. In this paper, a new synchronization scheme is proposed in Direct Sequence (DS) UWB system using Perfect Punctured Binary Sequence Pairs (PPBSP) as the preamble. It can acquire both Pseudo-Noise (PN) sequence and frame synchronization at the same time. The properties and the combinatorial admis sibility conditions of PPBSP are presented. The simulation results show that PPBSP is good for synchronization by their good cross-correlation properties both under Additive White Gaussian Noise (AWGN) channel and modified Saleh-Valenzuela channel.展开更多
A cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer with a hybrid automatic repeat request (HARQ) protocol at the data link layer (LL) is presented, in cooperative relay syst...A cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer with a hybrid automatic repeat request (HARQ) protocol at the data link layer (LL) is presented, in cooperative relay system over Nakagami-m fading channels with perfect and imperfect channel state information (CSI). In order to maximize spectral efficiency (SE) under delay and packet error rate (PER) performance constraints, a state transition model and an optimization framework with perfect CSI are presented. Then the framework is extended to cooperative relay system with imperfect CSI. The numerical results show that the scheme can achieve maximum SE while satisfying transmitting delay requirements. Compared with the imperfect CSI, the average PER with perfect CSI is much lower and the spectral efficiency is much higher.展开更多
Electromagnetic tomography(EMT) is a non-invasive imaging technique capable of mapping the conductivity and permeability of an object. In EMT, eddy currents are induced in the object by the activation coils,and the re...Electromagnetic tomography(EMT) is a non-invasive imaging technique capable of mapping the conductivity and permeability of an object. In EMT, eddy currents are induced in the object by the activation coils,and the receiving coils can measure the EMT voltages. When the activation frequency is significantly large, we can treat the metallic targets as electrically perfect conductors(EPCs). In this situation, a thin skin approximation is reasonable and this type of scattering problem can be effectively treated by the boundary element method(BEM)formulated through integration equations. In this study, we compute three-dimensional(3D) sensitivity matrix between the sensors due to an EPC perturbation. Efficiency improvement is achieved through the utility of scalar magnetic potential. Two EPC objects, one sphere and one cube shaped, are simulated. The results agree well with the H dot H formula. Overall, we conclude that BEM can be used to calculate the 3D sensitivity matrix of an EMT system efficiently. This method is a general one for any shaped objects while the H dot H solution is only capable of producing the response for a small ball.展开更多
In this paper, we apply the perfect difference codes in wireless infrared systems considering the diffuse indoor optical wireless configuration. The bit error rate performance of the uplink wireless infrared system us...In this paper, we apply the perfect difference codes in wireless infrared systems considering the diffuse indoor optical wireless configuration. The bit error rate performance of the uplink wireless infrared system using Gaussian approximations is analyzed taking into account the effects of multiple-access interference, the ambient light noise, and the dark current. The proposed system also uses the compact encoder and decoder architecture resulting in a low cost system.展开更多
"The year of 2022 marked the70th anniversary of the founding of the China Council for the Promotion of International Trade(CCPIT),and it was also a milestone in the development history of trade promotion.Under th..."The year of 2022 marked the70th anniversary of the founding of the China Council for the Promotion of International Trade(CCPIT),and it was also a milestone in the development history of trade promotion.Under the strong leadership of the Central Committee of the Communist Party of China(CPC)with Comrade Xi Jinping at its core,the national trade promotion system faced up to difficulties,forged ahead.展开更多
Afirst-class forwarding agent company approved by the Ministry of Foreign Trade and Economic Cooperation,the Ministry of Communication, the General Customs and the Civil Aviation Administration of China, the Shanghai ...Afirst-class forwarding agent company approved by the Ministry of Foreign Trade and Economic Cooperation,the Ministry of Communication, the General Customs and the Civil Aviation Administration of China, the Shanghai Jinhai Jieya International Forwarding Co. Ltd comprises the Shanghai Haigang Industrial General Company,Shanghai Jin Jiang Associated Corporation (Group) and Hongkong Jieya Air Freight Forwarding Corporation, in the form of a joint venture.展开更多
Although it has stipulated a treatment system for juvenile delinquents in the existing law of China,the related provisions are scattered throughout different legal norms and need to be integrated and perfected.The exi...Although it has stipulated a treatment system for juvenile delinquents in the existing law of China,the related provisions are scattered throughout different legal norms and need to be integrated and perfected.The existing treatment of juvenile delinquents,including administrative treatment and judicial treatment,mainly faces the following problems:(a)The treatment measures are too rough and simple to effectively combine punishment with leniency effectively;(b)The hierarchical treatment measures are not perfect enough procedurally;(c)The non-criminal treatment measures do not produce the desired effect.Based on a good understanding of the basic connotations of the hierarchical treatment system for juvenile delinquents,it is necessary to take the following steps:(a)Treat the juvenile delinquents in appropriate ways according to the subject,specific content,and severity of juvenile delinquencies;(b)Take highly-targeted and flexible treatment measures at different stages of criminal proceedings,namely,take criminal coercive measures against juvenile delinquents in a prudent manner and impose criminal punishments against them in a relatively lenient manner,to better help them return to society.展开更多
Cloud computing is one of the fastest growing and popular computer technologies, and there are more and more enterprise services based on the cloud computing. In order to save costs, more and more enterprises and thei...Cloud computing is one of the fastest growing and popular computer technologies, and there are more and more enterprise services based on the cloud computing. In order to save costs, more and more enterprises and their employees have hired the enterprise cloud services, and put much important information in the cloud gradually. Cloud service systems have become the main targets of malicious attacks. However, the cloud computing technologies are still not perfect, and the management and maintenance of enterprise cloud services are more complex compared to traditional network services of cloud computing. So, enterprise cloud services are more likely to encounter some security problems, and the influenced scale of these security problems is broad. But there are few researches on the security of enterprise cloud services. In this paper, we analyze the software as a service（Saa S） enterprise cloud services and introduce the research status of security problems in cloud computing environment. Combining with the analysis of the characteristics and application architecture of Saa S enterprise cloud services, we propose the security problems analysis model, the analysis system architecture and the relational model. Our researches can support further research of the automatic generation of solutions and guide the deployment of security policies of Saa S enterprise cloud services.展开更多
During the Spring Festival in 2022,China Cultural Center in Mexico focused on the themes of Winter Olympics with Ice and Snow,the 50th anniversary of the establishment of diplomatic relations between China and Mexico,...During the Spring Festival in 2022,China Cultural Center in Mexico focused on the themes of Winter Olympics with Ice and Snow,the 50th anniversary of the establishment of diplomatic relations between China and Mexico,friendship between the two countries,etc.,and cooperated with 20-plus Chinese and Mexican institutions to hold 11 categories of 180-plus Spring Festival celebration activities,such as Year of the Tiger Costume Contest,Happy Spring Festival Quiz Show,the 8th Children's Painting Competition:China in My Imagination in the theme of Winter Olympics and ice&snow sports.展开更多
Aerospace is always a pursuit of humans,not only out of desire for knowledge,but also out of persevering ambition.Ground support equipment(GSE)and relevant systems are of vital significance,which is fundamental to spa...Aerospace is always a pursuit of humans,not only out of desire for knowledge,but also out of persevering ambition.Ground support equipment(GSE)and relevant systems are of vital significance,which is fundamental to space system programs and projects.Though there are standards for ESG,the standards for ESG inspection and maintenance are necessary to perfect the whole process.展开更多
We investigate the phenomenon of coherent perfect absorption in a high-order system with three passive resonators coupled to a super-surface to form this three-state coherent perfect absorber. The effective parity tim...We investigate the phenomenon of coherent perfect absorption in a high-order system with three passive resonators coupled to a super-surface to form this three-state coherent perfect absorber. The effective parity time (PT) symmetry in the passive system has received much attention, and in this open three-state PT symmetric system, the incident wave is used as the effective gain instead of balancing the material gain and loss. We analyze the variation of coherent perfect absorption of this system with the coupling coefficient of the system by simulation.展开更多
文摘The index systems are not only the tools to evaluate existing practice results, but also the guides to the future development direction and development way of practical activities. ＂Well-off society＂ is a relatively vague concept, and the contents of it ceaselessly change with the advancement of society and the development of productivity. Now the construction of a well-off society in an all-round way enters a critical stage, so the original evaluation standards must change with gradual advancement of the construction goal of a well-off society. So it is very necessary for us to build a comprehensive evaluation index system and make it better and better to provide effective statistical consultation and statistical supervision for constructing a well-off society in an all-round way. This paper attempts to analyze the current evaluation index system, then puts forward the general thinking and flame work of the index system of building a well-off society in an all-round way.
基金supported in part by the National Natural Science Foundation of China(61933007,62273087,62273088,U21A2019)the Shanghai Pujiang Program of China(22PJ1400400)+2 种基金the Hainan Province Science and Technology Special Fund of China(ZDYF2022SHFZ105)the Royal Society of U.K.the Alexander von Humboldt Foundation of Germany
文摘In this paper, the attack detection problem is investigated for a class of closed-loop systems subjected to unknownbutbounded noises in the presence of stealthy attacks. The measurement outputs from the sensors are quantized before transmission.A specific type of perfect stealthy attack, which meets certain rather stringent conditions, is taken into account. Such attacks could be injected by adversaries into both the sensor-toestimator and controller-to-actuator channels, with the aim of disrupting the normal data flow. For the purpose of defending against these perfect stealthy attacks, a novel scheme based on watermarks is developed. This scheme includes the injection of watermarks(applied to data prior to quantization) and the recovery of data(implemented before the data reaches the estimator).The watermark-based scheme is designed to be both timevarying and hidden from adversaries through incorporating a time-varying and bounded watermark signal. Subsequently, a watermark-based attack detection strategy is proposed which thoroughly considers the characteristics of perfect stealthy attacks,thereby ensuring that an alarm is activated upon the occurrence of such attacks. An example is provided to demonstrate the efficacy of the proposed mechanism for detecting attacks.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 90203018, 10474104, and 10447133, and the Knowledge Innovation Program （KIP） of the Chinese Academy of Sciences, the National Fundamental Research Program of China under Grant No. 2001CB309310
文摘The quantum state transmission through the medium of high-dimensional many-particle system （boson or spinless fermion） is generally studied with a symmetry analysis. We discover that, if the spectrum of a Hamiltonian matches the symmetry of a fermion or boson system in a certain fashion, a perfect quantum state transfer can be implemented without any operation on the medium with pre-engineered nearest neighbor （NN）. We also study a simple but realistic near half-filled tight-bindlng fermion system wlth uniform NN hopping integral. We show that an arbitrary many-particle state near the fermi surface can be perfectly transferred to its translational counterpart.
基金the Deanship of Graduate Studies at Jouf University for funding and supporting this research through the initiative of DGS,Graduate Students Research Support(GSR)at Jouf University,Saudi Arabia.
文摘Wireless medical sensor networks(WMSNs)play a significant role in increasing the availability of remote healthcare systems.The vital and physiological data of the patient can be collected using the WMSN via sensor nodes that are placed on his/her body and then transmitted remotely to a healthcare professional for proper diagnosis.The protection of the patient’s privacy and their data from unauthorized access is a major concern in such systems.Therefore,an authentication scheme with a high level of security is one of the most effective mechanisms by which to address these security concerns.Many authentication schemes for remote patient monitoring have been proposed recently.However,the majority of these schemes are extremely vulnerable to attacks and are unsuitable for practical use.This paper proposes a secure three-factor authentication scheme for a patient-monitoring healthcare system that operates remotely using a WMSN.The proposed authentication scheme is formally verified using the Burrows,Abadi and Needham’s(BAN)logic model and an automatic cryptographic protocol verifier(ProVerif)tool.We show that our authentication scheme can prevent relevant types of security breaches in a practical context according to the discussed possible attack scenarios.Comparisons of the security and performance are carried out with recently proposed authentication schemes.The results of the analysis show that the proposed authentication scheme is secure and practical for use,with reasonable storage space,computation,and communication efficiency.
文摘With the emergence of Internet of Things,modern control systems have to deal with the big data from the ubiquitous information sensing mobile devices,cameras,microphones,radio-frequency identification devices,wireless sensor networks,etc.,which is often beyond the capacity of traditional control technologies.To deal with this issue,the rapidly developing cloud computing may provide a perfect platform for big data storage and processing,controller design,and performance optimization.Thereby,with the extension and application of the basic theory and method of cloud computing defined by software in the field of automatic control,cloud control systems have recently attracted much attention from both researchers and engineers.
文摘With the emergence of Internet of Things,modern control systems have to deal with the big data from the ubiquitous information sensing mobile devices,cameras,microphones,radio-frequency identification devices,wireless sensor networks,etc.,which is often beyond the capacity of traditional control technologies.To deal with this issue,the rapidly developing cloud computing may provide a perfect platform for big data storage and processing,controller design,and performance optimization.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11864018 and 11574229)Scientific Research Foundation of the Education Department of Jiangxi Province of China(Grant No.GJJ170645)Doctor Startup Fund of the Natural Science of Jinggangshan University,China(Grant No.JZB16003)
文摘Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber（CPA）beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices.
文摘The healthcare internet of things(IoT)system has dramatically reshaped this important industry sector.This system employs the latest technology of IoT and wireless medical sensor networks to support the reliable connection of patients and healthcare providers.The goal is the remote monitoring of a patient’s physiological data by physicians.Moreover,this system can reduce the number and expenses of healthcare centers,make up for the shortage of healthcare centers in remote areas,enable consultation with expert physicians around the world,and increase the health awareness of communities.The major challenges that affect the rapid deployment and widespread acceptance of such a system are the weaknesses in the authentication process,which should maintain the privacy of patients,and the integrity of remote medical instructions.Current research results indicate the need of a flexible authentication scheme.This study proposes a scheme with enhanced security for healthcare IoT systems,called an end-to-end authentication scheme for healthcare IoT systems,that is,an E2EA.The proposed scheme supports security services such as a strong and flexible authentication process,simultaneous anonymity of the patient and physician,and perfect forward secrecy services.A security analysis based on formal and informal methods demonstrates that the proposed scheme can resist numerous security-related attacks.A comparison with related authentication schemes shows that the proposed scheme is efficient in terms of communication,computation,and storage,and therefore cannot only offer attractive security services but can reasonably be applied to healthcare IoT systems.
基金Supported by the Key Project of Chinese Ministry of Education(No.03035)the National High Technology Research and Development Program of China (863 Program) (No.2003AA 123240)the National Natural Science Foundation of China(No.60372097).
文摘Ultra WideBand (UWB) radio is a new wireless technology that transmits extremely short duration radio impulses. In this paper, a new synchronization scheme is proposed in Direct Sequence (DS) UWB system using Perfect Punctured Binary Sequence Pairs (PPBSP) as the preamble. It can acquire both Pseudo-Noise (PN) sequence and frame synchronization at the same time. The properties and the combinatorial admis sibility conditions of PPBSP are presented. The simulation results show that PPBSP is good for synchronization by their good cross-correlation properties both under Additive White Gaussian Noise (AWGN) channel and modified Saleh-Valenzuela channel.
基金Sponsored by the National Science and Technology Major Special Project of China (Grant No.2011ZX03003-003-02)the Natural Science Foundation of China (Grant No. 60972070)+2 种基金the Natural Science Foundation of Chongqing (Grant No. CSTC2009BA2090)the Foundation of Chongqing Educational Committee ( Grant No. KJ100514)the Special Fund of Chongqing Key Laboratory
文摘A cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer with a hybrid automatic repeat request (HARQ) protocol at the data link layer (LL) is presented, in cooperative relay system over Nakagami-m fading channels with perfect and imperfect channel state information (CSI). In order to maximize spectral efficiency (SE) under delay and packet error rate (PER) performance constraints, a state transition model and an optimization framework with perfect CSI are presented. Then the framework is extended to cooperative relay system with imperfect CSI. The numerical results show that the scheme can achieve maximum SE while satisfying transmitting delay requirements. Compared with the imperfect CSI, the average PER with perfect CSI is much lower and the spectral efficiency is much higher.
基金the National Natural Science Foundation of China(No.50937005)the Shanghai Maritime University Science and Technology Program(No.20120064)
文摘Electromagnetic tomography(EMT) is a non-invasive imaging technique capable of mapping the conductivity and permeability of an object. In EMT, eddy currents are induced in the object by the activation coils,and the receiving coils can measure the EMT voltages. When the activation frequency is significantly large, we can treat the metallic targets as electrically perfect conductors(EPCs). In this situation, a thin skin approximation is reasonable and this type of scattering problem can be effectively treated by the boundary element method(BEM)formulated through integration equations. In this study, we compute three-dimensional(3D) sensitivity matrix between the sensors due to an EPC perturbation. Efficiency improvement is achieved through the utility of scalar magnetic potential. Two EPC objects, one sphere and one cube shaped, are simulated. The results agree well with the H dot H formula. Overall, we conclude that BEM can be used to calculate the 3D sensitivity matrix of an EMT system efficiently. This method is a general one for any shaped objects while the H dot H solution is only capable of producing the response for a small ball.
文摘In this paper, we apply the perfect difference codes in wireless infrared systems considering the diffuse indoor optical wireless configuration. The bit error rate performance of the uplink wireless infrared system using Gaussian approximations is analyzed taking into account the effects of multiple-access interference, the ambient light noise, and the dark current. The proposed system also uses the compact encoder and decoder architecture resulting in a low cost system.
文摘"The year of 2022 marked the70th anniversary of the founding of the China Council for the Promotion of International Trade(CCPIT),and it was also a milestone in the development history of trade promotion.Under the strong leadership of the Central Committee of the Communist Party of China(CPC)with Comrade Xi Jinping at its core,the national trade promotion system faced up to difficulties,forged ahead.
文摘Afirst-class forwarding agent company approved by the Ministry of Foreign Trade and Economic Cooperation,the Ministry of Communication, the General Customs and the Civil Aviation Administration of China, the Shanghai Jinhai Jieya International Forwarding Co. Ltd comprises the Shanghai Haigang Industrial General Company,Shanghai Jin Jiang Associated Corporation (Group) and Hongkong Jieya Air Freight Forwarding Corporation, in the form of a joint venture.
文摘Although it has stipulated a treatment system for juvenile delinquents in the existing law of China,the related provisions are scattered throughout different legal norms and need to be integrated and perfected.The existing treatment of juvenile delinquents,including administrative treatment and judicial treatment,mainly faces the following problems:(a)The treatment measures are too rough and simple to effectively combine punishment with leniency effectively;(b)The hierarchical treatment measures are not perfect enough procedurally;(c)The non-criminal treatment measures do not produce the desired effect.Based on a good understanding of the basic connotations of the hierarchical treatment system for juvenile delinquents,it is necessary to take the following steps:(a)Treat the juvenile delinquents in appropriate ways according to the subject,specific content,and severity of juvenile delinquencies;(b)Take highly-targeted and flexible treatment measures at different stages of criminal proceedings,namely,take criminal coercive measures against juvenile delinquents in a prudent manner and impose criminal punishments against them in a relatively lenient manner,to better help them return to society.
基金supported by National Natural Science Foundation of China(Nos.61300049,61502197 and 61503044)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20120061120059)+2 种基金the China Postdoctoral Science Foundation(No.2011M500612)the Key Program for Science and Technology Development of Jilin Province of China(No.20130206052GX)the Natural Science Research Foundation of Jilin Province of China(Nos.20140520069JH,20150101054JC and 20150520058JH)
文摘Cloud computing is one of the fastest growing and popular computer technologies, and there are more and more enterprise services based on the cloud computing. In order to save costs, more and more enterprises and their employees have hired the enterprise cloud services, and put much important information in the cloud gradually. Cloud service systems have become the main targets of malicious attacks. However, the cloud computing technologies are still not perfect, and the management and maintenance of enterprise cloud services are more complex compared to traditional network services of cloud computing. So, enterprise cloud services are more likely to encounter some security problems, and the influenced scale of these security problems is broad. But there are few researches on the security of enterprise cloud services. In this paper, we analyze the software as a service（Saa S） enterprise cloud services and introduce the research status of security problems in cloud computing environment. Combining with the analysis of the characteristics and application architecture of Saa S enterprise cloud services, we propose the security problems analysis model, the analysis system architecture and the relational model. Our researches can support further research of the automatic generation of solutions and guide the deployment of security policies of Saa S enterprise cloud services.
文摘During the Spring Festival in 2022,China Cultural Center in Mexico focused on the themes of Winter Olympics with Ice and Snow,the 50th anniversary of the establishment of diplomatic relations between China and Mexico,friendship between the two countries,etc.,and cooperated with 20-plus Chinese and Mexican institutions to hold 11 categories of 180-plus Spring Festival celebration activities,such as Year of the Tiger Costume Contest,Happy Spring Festival Quiz Show,the 8th Children's Painting Competition:China in My Imagination in the theme of Winter Olympics and ice&snow sports.
文摘Aerospace is always a pursuit of humans,not only out of desire for knowledge,but also out of persevering ambition.Ground support equipment(GSE)and relevant systems are of vital significance,which is fundamental to space system programs and projects.Though there are standards for ESG,the standards for ESG inspection and maintenance are necessary to perfect the whole process.
文摘We investigate the phenomenon of coherent perfect absorption in a high-order system with three passive resonators coupled to a super-surface to form this three-state coherent perfect absorber. The effective parity time (PT) symmetry in the passive system has received much attention, and in this open three-state PT symmetric system, the incident wave is used as the effective gain instead of balancing the material gain and loss. We analyze the variation of coherent perfect absorption of this system with the coupling coefficient of the system by simulation.
