Dear Editor,This letter addresses the resilient distributed cooperative control problem of a virtually coupled train convoy under stochastic disturbances and cyber attacks.The main purpose is to achieve distributed co...Dear Editor,This letter addresses the resilient distributed cooperative control problem of a virtually coupled train convoy under stochastic disturbances and cyber attacks.The main purpose is to achieve distributed coordination of virtually coupled high-speed trains with the prescribed inter-train distance and same cruise velocity.展开更多
Solar insecticidal lamps(SIL) can effectively control pests and reduce the use of pesticides. Combining SIL and Internet of Things(IoT) has formed a new type of agricultural IoT,known as SIL-IoT, which can improve the...Solar insecticidal lamps(SIL) can effectively control pests and reduce the use of pesticides. Combining SIL and Internet of Things(IoT) has formed a new type of agricultural IoT,known as SIL-IoT, which can improve the effectiveness of migratory phototropic pest control. However, since the SIL is connected to the Internet, it is vulnerable to various security issues.These issues can lead to serious consequences, such as tampering with the parameters of SIL, illegally starting and stopping SIL,etc. In this paper, we describe the overall security requirements of SIL-IoT and present an extensive survey of security and privacy solutions for SIL-IoT. We investigate the background and logical architecture of SIL-IoT, discuss SIL-IoT security scenarios, and analyze potential attacks. Starting from the security requirements of SIL-IoT we divide them into six categories, namely privacy, authentication, confidentiality, access control, availability,and integrity. Next, we describe the SIL-IoT privacy and security solutions, as well as the blockchain-based solutions. Based on the current survey, we finally discuss the challenges and future research directions of SIL-IoT.展开更多
The speed and pace of the transmission of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2;also referred to as novel Coronavirus 2019 and COVID-19)have resulted in a global pandemic,with significant health,f...The speed and pace of the transmission of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2;also referred to as novel Coronavirus 2019 and COVID-19)have resulted in a global pandemic,with significant health,financial,political,and other implications.There have been various attempts to manage COVID-19 and other pandemics using technologies such as Internet of Things(IoT)and 5G/6G communications.However,we also need to ensure that IoT devices used to facilitate COVID-19 monitoring and treatment(e.g.,medical IoT devices)are secured,as the compromise of such devices can have significant consequences(e.g.,life-threatening risks to COVID-19 patients).Hence,in this paper we comprehensively survey existing IoT-related solutions,potential security and privacy risks and their requirements.For example,we classify existing security and privacy solutions into five categories,namely:authentication and access control solutions,key management and cryptography solutions,blockchain-based solutions,intrusion detection systems,and privacy-preserving solutions.In each category,we identify the associated challenges.We also identify a number of recommendations to inform future research.展开更多
Connected automated vehicles(CAVs)serve as a promising enabler for future intelligent transportation systems because of their capabilities in improving traffic efficiency and driving safety,and reducing fuel consumpti...Connected automated vehicles(CAVs)serve as a promising enabler for future intelligent transportation systems because of their capabilities in improving traffic efficiency and driving safety,and reducing fuel consumption and vehicle emissions.A fundamental issue in CAVs is platooning control that empowers a convoy of CAVs to be cooperatively maneuvered with desired longitudinal spacings and identical velocities on roads.This paper addresses the issue of resilient and safe platooning control of CAVs subject to intermittent denial-of-service(DoS)attacks that disrupt vehicle-to-vehicle communications.First,a heterogeneous and uncertain vehicle longitudinal dynamic model is presented to accommodate a variety of uncertainties,including diverse vehicle masses and engine inertial delays,unknown and nonlinear resistance forces,and a dynamic platoon leader.Then,a resilient and safe distributed longitudinal platooning control law is constructed with an aim to preserve simultaneous individual vehicle stability,attack resilience,platoon safety and scalability.Furthermore,a numerically efficient offline design algorithm for determining the desired platoon control law is developed,under which the platoon resilience against DoS attacks can be maximized but the anticipated stability,safety and scalability requirements remain preserved.Finally,extensive numerical experiments are provided to substantiate the efficacy of the proposed platooning method.展开更多
In this paper,a new distributed consensus tracking protocol incorporating local disturbance rejection is devised for a multi-agent system with heterogeneous dynamic uncertainties and disturbances over a directed graph...In this paper,a new distributed consensus tracking protocol incorporating local disturbance rejection is devised for a multi-agent system with heterogeneous dynamic uncertainties and disturbances over a directed graph.It is of two-degree-of-freedom nature.Specifically,a robust distributed controller is designed for consensus tracking,while a local disturbance estimator is designed for each agent without requiring the input channel information of disturbances.The condition for asymptotic disturbance rejection is derived.Moreover,even when the disturbance model is not exactly known,the developed method also provides good disturbance-rejection performance.Then,a robust stabilization condition with less conservativeness is derived for the whole multi-agent system.Further,a design algorithm is given.Finally,comparisons with the conventional one-degree-of-freedombased distributed disturbance-rejection method for mismatched disturbances and the distributed extended-state observer for matched disturbances validate the developed method.展开更多
For unachievable tracking problems, where the system output cannot precisely track a given reference, achieving the best possible approximation for the reference trajectory becomes the objective. This study aims to in...For unachievable tracking problems, where the system output cannot precisely track a given reference, achieving the best possible approximation for the reference trajectory becomes the objective. This study aims to investigate solutions using the Ptype learning control scheme. Initially, we demonstrate the necessity of gradient information for achieving the best approximation.Subsequently, we propose an input-output-driven learning gain design to handle the imprecise gradients of a class of uncertain systems. However, it is discovered that the desired performance may not be attainable when faced with incomplete information.To address this issue, an extended iterative learning control scheme is introduced. In this scheme, the tracking errors are modified through output data sampling, which incorporates lowmemory footprints and offers flexibility in learning gain design.The input sequence is shown to converge towards the desired input, resulting in an output that is closest to the given reference in the least square sense. Numerical simulations are provided to validate the theoretical findings.展开更多
This paper reports a wind-powered water pumping system implemented in rural side of Pakistan. The design methodology presented in this paper shall enhance the efficiency of the existing Savonius turbine's performa...This paper reports a wind-powered water pumping system implemented in rural side of Pakistan. The design methodology presented in this paper shall enhance the efficiency of the existing Savonius turbine's performance by modifying it aerodynamically. Blades with different twist angles are designed in Solid Edge and analyzed using computational fluid dynamics(CFD) with ANSYS FLUENT software. Static and rotational analyses are performed to get optimized twist angle and results are highlighted. The performances of the turbine in both static and rotational analyses are compared.展开更多
Fusion is an ideal clean energy for human being utilized in the future. Much more significant research progress for such new energy exploited in a limited finite space of the high temperature plasma flow constrained b...Fusion is an ideal clean energy for human being utilized in the future. Much more significant research progress for such new energy exploited in a limited finite space of the high temperature plasma flow constrained by strong magnetic fields of superconducting magnets has been achieved on Tokamak research, which comes to a new era with the international joint efforts from China, Europe, India, Japan, Korea, Russia and United States for building the international thermonuclear experimental reactor (ITER). The plasma chamber and magnets are key components of a fusion power reactor system.展开更多
This work conducts robust H^(∞)analysis for a class of quantum systems subject to perturbations in the interaction Hamiltonian.A necessary and sufficient condition for the robustly strict bounded real property of thi...This work conducts robust H^(∞)analysis for a class of quantum systems subject to perturbations in the interaction Hamiltonian.A necessary and sufficient condition for the robustly strict bounded real property of this type of uncertain quantum system is proposed.This paper focuses on the study of coherent robust H^(∞)controller design for quantum systems with uncertainties in the interaction Hamiltonian.The desired controller is connected with the uncertain quantum system through direct and indirect couplings.A necessary and sufficient condition is provided to build a connection between the robust H^(∞)control problem and the scaled H^(∞)control problem.A numerical procedure is provided to obtain coefficients of a coherent controller.An example is presented to illustrate the controller design method.展开更多
Wide bandgap(WBG)semiconductors,such as silicon carbide(SiC)and gallium nitride(GaN),exhibit superior physical properties and demonstrate great potential for replacing conventional silicon(Si)semiconductors with WBG t...Wide bandgap(WBG)semiconductors,such as silicon carbide(SiC)and gallium nitride(GaN),exhibit superior physical properties and demonstrate great potential for replacing conventional silicon(Si)semiconductors with WBG technology,pushing the boundaries of power devices to handle higher blocking voltages,switching frequencies,output power levels,and operating temperatures.However,tradeoffs in switching performance and converter efficiency when substituting GaN devices for Si and SiC counterparts are not well-defined,especially in a cascode configuration.Additional research with further detailed investigation and analysis is necessitated for medium-voltage GaN devices in power converter applications.Therefore,the aim of this research is to experimentally investigate the impact of emerging 650/900 V cascode GaN devices on bidirectional dc-dc converters that are suitable for energy storage and distributed renewable energy systems.Dynamic characteristics of Si,SiC,and cascode GaN power devices are examined through the double-pulse test(DPT)circuit at different gate resistance values,device currents,and DC bus voltages.Furthermore,the switching behavior and energy loss as well as the rate of voltage and current changes over the time are studied and analyzed at various operating conditions.A 500 W experimental converter prototype is implemented to validate the benefits of cascode GaN devices on the converter operation and performance.Comprehensive analysis of the power losses and efficiency improvements for Si-based,SiC-based,and GaN-based converters are performed and evaluated as the switching frequency,working temperature,and output power level are in-creased.The experimental results reveal significant improvements in switching performance and energy efficiency from the emerging cascode GaN devices in the bidirectional converters.展开更多
High-speed motor has the characteristics of high frequency, high temperature, and more stress, resulting in the field distribution inside the motor being complicated. To better study the electromagnetic characteristic...High-speed motor has the characteristics of high frequency, high temperature, and more stress, resulting in the field distribution inside the motor being complicated. To better study the electromagnetic characteristics of silicon steel sheet for high-speed motor. In this article, a study on the calculation model of silicon sheet electromagnetic characteristics considers the effects of electromagnetic, stress, and temperature factors. The study is divided into two parts, one is to propose the calculation model of silicon steel sheet’s permeability;the other is to improve the calculation model of silicon steel sheet’s loss. Then, the magnetic field, stress field, and temperature field of a surface mount high speed permanent magnet motor(SMHSPMSM) are analyzed by finite element method(FEM), and the results under the consideration of magnetic, stress, and temperature factors are brought into the calculation model for calculation. Finally, the accuracy of the calculation model for electromagnetic characteristics of silicon steel sheet is verified by comparing the calculated results with the finite element results.展开更多
The P-type update law has been the mainstream technique used in iterative learning control(ILC)systems,which resembles linear feedback control with asymptotical convergence.In recent years,finite-time control strategi...The P-type update law has been the mainstream technique used in iterative learning control(ILC)systems,which resembles linear feedback control with asymptotical convergence.In recent years,finite-time control strategies such as terminal sliding mode control have been shown to be effective in ramping up convergence speed by introducing fractional power with feedback.In this paper,we show that such mechanism can equally ramp up the learning speed in ILC systems.We first propose a fractional power update rule for ILC of single-input-single-output linear systems.A nonlinear error dynamics is constructed along the iteration axis to illustrate the evolutionary converging process.Using the nonlinear mapping approach,fast convergence towards the limit cycles of tracking errors inherently existing in ILC systems is proven.The limit cycles are shown to be tunable to determine the steady states.Numerical simulations are provided to verify the theoretical results.展开更多
In this paper, we extend the state-space kriging(SSK) modeling technique presented in a previous work by the authors in order to consider non-autonomous systems. SSK is a data-driven method that computes predictions a...In this paper, we extend the state-space kriging(SSK) modeling technique presented in a previous work by the authors in order to consider non-autonomous systems. SSK is a data-driven method that computes predictions as linear combinations of past outputs. To model the nonlinear dynamics of the system, we propose the kernel-based state-space kriging(K-SSK), a new version of the SSK where kernel functions are used instead of resorting to considerations about the locality of the data. Also, a Kalman filter can be used to improve the predictions at each time step in the case of noisy measurements. A constrained tracking nonlinear model predictive control(NMPC) scheme using the black-box input-output model obtained by means of the K-SSK prediction method is proposed. Finally, a simulation example and a real experiment are provided in order to assess the performance of the proposed controller.展开更多
Dear Editor,This letter investigates the fixed-time trajectory tracking controller design for nonholonomic chained systems with static state constraints.Firstly,a fixed-time tracking control law is given to carry out ...Dear Editor,This letter investigates the fixed-time trajectory tracking controller design for nonholonomic chained systems with static state constraints.Firstly,a fixed-time tracking control law is given to carry out relay switching,which divides the controller development process into two stages.展开更多
With the deep combination of both modern information technology and traditional agriculture,the era of agriculture 4.0,which takes the form of smart agriculture,has come.Smart agriculture provides solutions for agricu...With the deep combination of both modern information technology and traditional agriculture,the era of agriculture 4.0,which takes the form of smart agriculture,has come.Smart agriculture provides solutions for agricultural intelligence and automation.However,information security issues cannot be ignored with the development of agriculture brought by modern information technology.In this paper,three typical development modes of smart agriculture(precision agriculture,facility agriculture,and order agriculture)are presented.Then,7 key technologies and 11 key applications are derived from the above modes.Based on the above technologies and applications,6 security and privacy countermeasures(authentication and access control,privacy-preserving,blockchain-based solutions for data integrity,cryptography and key management,physical countermeasures,and intrusion detection systems)are summarized and discussed.Moreover,the security challenges of smart agriculture are analyzed and organized into two aspects:1)agricultural production,and 2)information technology.Most current research projects have not taken agricultural equipment as potential security threats.Therefore,we did some additional experiments based on solar insecticidal lamps Internet of Things,and the results indicate that agricultural equipment has an impact on agricultural security.Finally,more technologies(5 G communication,fog computing,Internet of Everything,renewable energy management system,software defined network,virtual reality,augmented reality,and cyber security datasets for smart agriculture)are described as the future research directions of smart agriculture.展开更多
Vehicular communications and networking(VCN)is considered a billion-dollar industry.Its development not only possesses economic value,but also has enormous social potential.The earliest vehicular network started from ...Vehicular communications and networking(VCN)is considered a billion-dollar industry.Its development not only possesses economic value,but also has enormous social potential.The earliest vehicular network started from the dedicated short range networks,such as the IEEE 802.11p standard established at the beginning of this century.In recent years,the public access network based VCN has been rapidly advanced.For example,LTE-V based on 4G LTE is under standardization。展开更多
The advent of healthcare information management systems(HIMSs)continues to produce large volumes of healthcare data for patient care and compliance and regulatory requirements at a global scale.Analysis of this big da...The advent of healthcare information management systems(HIMSs)continues to produce large volumes of healthcare data for patient care and compliance and regulatory requirements at a global scale.Analysis of this big data allows for boundless potential outcomes for discovering knowledge.Big data analytics(BDA)in healthcare can,for instance,help determine causes of diseases,generate effective diagnoses,enhance Qo S guarantees by increasing efficiency of the healthcare delivery and effectiveness and viability of treatments,generate accurate predictions of readmissions,enhance clinical care,and pinpoint opportunities for cost savings.However,BDA implementations in any domain are generally complicated and resource-intensive with a high failure rate and no roadmap or success strategies to guide the practitioners.In this paper,we present a comprehensive roadmap to derive insights from BDA in the healthcare(patient care)domain,based on the results of a systematic literature review.We initially determine big data characteristics for healthcare and then review BDA applications to healthcare in academic research focusing particularly on No SQL databases.We also identify the limitations and challenges of these applications and justify the potential of No SQL databases to address these challenges and further enhance BDA healthcare research.We then propose and describe a state-of-the-art BDA architecture called Med-BDA for healthcare domain which solves all current BDA challenges and is based on the latest zeta big data paradigm.We also present success strategies to ensure the working of Med-BDA along with outlining the major benefits of BDA applications to healthcare.Finally,we compare our work with other related literature reviews across twelve hallmark features to justify the novelty and importance of our work.The aforementioned contributions of our work are collectively unique and clearly present a roadmap for clinical administrators,practitioners and professionals to successfully implement BDA initiatives in their organizations.展开更多
基金the National Natural Science Foundation of China(62303240)the Natural Science Foundation of Jiangsu Province of China(BK20230356)+1 种基金the Natural Science Research Start-Up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(NY222033)the Natural Science Foundation for Colleges and Universities in Jiangsu Province(22KJB120001)。
文摘Dear Editor,This letter addresses the resilient distributed cooperative control problem of a virtually coupled train convoy under stochastic disturbances and cyber attacks.The main purpose is to achieve distributed coordination of virtually coupled high-speed trains with the prescribed inter-train distance and same cruise velocity.
基金supported in part by the National Natural Science Foundation of China (62072248, 62072247)the Jiangsu Agriculture Science and Technology Innovation Fund (CX(21)3060)。
文摘Solar insecticidal lamps(SIL) can effectively control pests and reduce the use of pesticides. Combining SIL and Internet of Things(IoT) has formed a new type of agricultural IoT,known as SIL-IoT, which can improve the effectiveness of migratory phototropic pest control. However, since the SIL is connected to the Internet, it is vulnerable to various security issues.These issues can lead to serious consequences, such as tampering with the parameters of SIL, illegally starting and stopping SIL,etc. In this paper, we describe the overall security requirements of SIL-IoT and present an extensive survey of security and privacy solutions for SIL-IoT. We investigate the background and logical architecture of SIL-IoT, discuss SIL-IoT security scenarios, and analyze potential attacks. Starting from the security requirements of SIL-IoT we divide them into six categories, namely privacy, authentication, confidentiality, access control, availability,and integrity. Next, we describe the SIL-IoT privacy and security solutions, as well as the blockchain-based solutions. Based on the current survey, we finally discuss the challenges and future research directions of SIL-IoT.
基金supported in part by the Research Start-Up Fund for Talent Researcher of Nanjing Agricultural University(77H0603)。
文摘The speed and pace of the transmission of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2;also referred to as novel Coronavirus 2019 and COVID-19)have resulted in a global pandemic,with significant health,financial,political,and other implications.There have been various attempts to manage COVID-19 and other pandemics using technologies such as Internet of Things(IoT)and 5G/6G communications.However,we also need to ensure that IoT devices used to facilitate COVID-19 monitoring and treatment(e.g.,medical IoT devices)are secured,as the compromise of such devices can have significant consequences(e.g.,life-threatening risks to COVID-19 patients).Hence,in this paper we comprehensively survey existing IoT-related solutions,potential security and privacy risks and their requirements.For example,we classify existing security and privacy solutions into five categories,namely:authentication and access control solutions,key management and cryptography solutions,blockchain-based solutions,intrusion detection systems,and privacy-preserving solutions.In each category,we identify the associated challenges.We also identify a number of recommendations to inform future research.
基金supported in part by Australian Research Council Discovery Early Career Researcher Award(DE210100273)。
文摘Connected automated vehicles(CAVs)serve as a promising enabler for future intelligent transportation systems because of their capabilities in improving traffic efficiency and driving safety,and reducing fuel consumption and vehicle emissions.A fundamental issue in CAVs is platooning control that empowers a convoy of CAVs to be cooperatively maneuvered with desired longitudinal spacings and identical velocities on roads.This paper addresses the issue of resilient and safe platooning control of CAVs subject to intermittent denial-of-service(DoS)attacks that disrupt vehicle-to-vehicle communications.First,a heterogeneous and uncertain vehicle longitudinal dynamic model is presented to accommodate a variety of uncertainties,including diverse vehicle masses and engine inertial delays,unknown and nonlinear resistance forces,and a dynamic platoon leader.Then,a resilient and safe distributed longitudinal platooning control law is constructed with an aim to preserve simultaneous individual vehicle stability,attack resilience,platoon safety and scalability.Furthermore,a numerically efficient offline design algorithm for determining the desired platoon control law is developed,under which the platoon resilience against DoS attacks can be maximized but the anticipated stability,safety and scalability requirements remain preserved.Finally,extensive numerical experiments are provided to substantiate the efficacy of the proposed platooning method.
基金supported by the National Natural Science Foundation of China(62003010,61873006,61673053)the Beijing Postdoctoral Research Foundation(Q6041001202001)+1 种基金the Postdoctoral Research Foundation of Chaoyang District(Q1041001202101)the National Key Research and Development Project(2018YFC1602704,2018YFB1702704)。
文摘In this paper,a new distributed consensus tracking protocol incorporating local disturbance rejection is devised for a multi-agent system with heterogeneous dynamic uncertainties and disturbances over a directed graph.It is of two-degree-of-freedom nature.Specifically,a robust distributed controller is designed for consensus tracking,while a local disturbance estimator is designed for each agent without requiring the input channel information of disturbances.The condition for asymptotic disturbance rejection is derived.Moreover,even when the disturbance model is not exactly known,the developed method also provides good disturbance-rejection performance.Then,a robust stabilization condition with less conservativeness is derived for the whole multi-agent system.Further,a design algorithm is given.Finally,comparisons with the conventional one-degree-of-freedombased distributed disturbance-rejection method for mismatched disturbances and the distributed extended-state observer for matched disturbances validate the developed method.
基金supported by the National Natural Science Foundation of China (62173333, 12271522)Beijing Natural Science Foundation (Z210002)the Research Fund of Renmin University of China (2021030187)。
文摘For unachievable tracking problems, where the system output cannot precisely track a given reference, achieving the best possible approximation for the reference trajectory becomes the objective. This study aims to investigate solutions using the Ptype learning control scheme. Initially, we demonstrate the necessity of gradient information for achieving the best approximation.Subsequently, we propose an input-output-driven learning gain design to handle the imprecise gradients of a class of uncertain systems. However, it is discovered that the desired performance may not be attainable when faced with incomplete information.To address this issue, an extended iterative learning control scheme is introduced. In this scheme, the tracking errors are modified through output data sampling, which incorporates lowmemory footprints and offers flexibility in learning gain design.The input sequence is shown to converge towards the desired input, resulting in an output that is closest to the given reference in the least square sense. Numerical simulations are provided to validate the theoretical findings.
文摘This paper reports a wind-powered water pumping system implemented in rural side of Pakistan. The design methodology presented in this paper shall enhance the efficiency of the existing Savonius turbine's performance by modifying it aerodynamically. Blades with different twist angles are designed in Solid Edge and analyzed using computational fluid dynamics(CFD) with ANSYS FLUENT software. Static and rotational analyses are performed to get optimized twist angle and results are highlighted. The performances of the turbine in both static and rotational analyses are compared.
文摘Fusion is an ideal clean energy for human being utilized in the future. Much more significant research progress for such new energy exploited in a limited finite space of the high temperature plasma flow constrained by strong magnetic fields of superconducting magnets has been achieved on Tokamak research, which comes to a new era with the international joint efforts from China, Europe, India, Japan, Korea, Russia and United States for building the international thermonuclear experimental reactor (ITER). The plasma chamber and magnets are key components of a fusion power reactor system.
基金supported by the National Natural Science Foundation of China(61803132,61828303,61803389)the U.S.Office of Naval Research Global(N62909-19-1-2129)the Australian Research’s Discovery Projects Funding Scheme under Project DP190101566。
文摘This work conducts robust H^(∞)analysis for a class of quantum systems subject to perturbations in the interaction Hamiltonian.A necessary and sufficient condition for the robustly strict bounded real property of this type of uncertain quantum system is proposed.This paper focuses on the study of coherent robust H^(∞)controller design for quantum systems with uncertainties in the interaction Hamiltonian.The desired controller is connected with the uncertain quantum system through direct and indirect couplings.A necessary and sufficient condition is provided to build a connection between the robust H^(∞)control problem and the scaled H^(∞)control problem.A numerical procedure is provided to obtain coefficients of a coherent controller.An example is presented to illustrate the controller design method.
文摘Wide bandgap(WBG)semiconductors,such as silicon carbide(SiC)and gallium nitride(GaN),exhibit superior physical properties and demonstrate great potential for replacing conventional silicon(Si)semiconductors with WBG technology,pushing the boundaries of power devices to handle higher blocking voltages,switching frequencies,output power levels,and operating temperatures.However,tradeoffs in switching performance and converter efficiency when substituting GaN devices for Si and SiC counterparts are not well-defined,especially in a cascode configuration.Additional research with further detailed investigation and analysis is necessitated for medium-voltage GaN devices in power converter applications.Therefore,the aim of this research is to experimentally investigate the impact of emerging 650/900 V cascode GaN devices on bidirectional dc-dc converters that are suitable for energy storage and distributed renewable energy systems.Dynamic characteristics of Si,SiC,and cascode GaN power devices are examined through the double-pulse test(DPT)circuit at different gate resistance values,device currents,and DC bus voltages.Furthermore,the switching behavior and energy loss as well as the rate of voltage and current changes over the time are studied and analyzed at various operating conditions.A 500 W experimental converter prototype is implemented to validate the benefits of cascode GaN devices on the converter operation and performance.Comprehensive analysis of the power losses and efficiency improvements for Si-based,SiC-based,and GaN-based converters are performed and evaluated as the switching frequency,working temperature,and output power level are in-creased.The experimental results reveal significant improvements in switching performance and energy efficiency from the emerging cascode GaN devices in the bidirectional converters.
基金the Key International Cooperation of National Natural Science Foundation of China under Grant 51920105011Liaoning BaiQianWan Talents Programthe Natural Science Foundation of LiaoNing Province under Grant 2021-YQ-09。
文摘High-speed motor has the characteristics of high frequency, high temperature, and more stress, resulting in the field distribution inside the motor being complicated. To better study the electromagnetic characteristics of silicon steel sheet for high-speed motor. In this article, a study on the calculation model of silicon sheet electromagnetic characteristics considers the effects of electromagnetic, stress, and temperature factors. The study is divided into two parts, one is to propose the calculation model of silicon steel sheet’s permeability;the other is to improve the calculation model of silicon steel sheet’s loss. Then, the magnetic field, stress field, and temperature field of a surface mount high speed permanent magnet motor(SMHSPMSM) are analyzed by finite element method(FEM), and the results under the consideration of magnetic, stress, and temperature factors are brought into the calculation model for calculation. Finally, the accuracy of the calculation model for electromagnetic characteristics of silicon steel sheet is verified by comparing the calculated results with the finite element results.
基金supported by the National Natural Science Foundation of China(62173333)Australian Research Council Discovery Program(DP200101199)。
文摘The P-type update law has been the mainstream technique used in iterative learning control(ILC)systems,which resembles linear feedback control with asymptotical convergence.In recent years,finite-time control strategies such as terminal sliding mode control have been shown to be effective in ramping up convergence speed by introducing fractional power with feedback.In this paper,we show that such mechanism can equally ramp up the learning speed in ILC systems.We first propose a fractional power update rule for ILC of single-input-single-output linear systems.A nonlinear error dynamics is constructed along the iteration axis to illustrate the evolutionary converging process.Using the nonlinear mapping approach,fast convergence towards the limit cycles of tracking errors inherently existing in ILC systems is proven.The limit cycles are shown to be tunable to determine the steady states.Numerical simulations are provided to verify the theoretical results.
基金supported by the Agencia Estatal de Investigación (AEI)-Spain (PID2019-106212RB-C41/AEI/10.13039/501100011033)Junta de Andalucía and FEDER funds (P20_00546)。
文摘In this paper, we extend the state-space kriging(SSK) modeling technique presented in a previous work by the authors in order to consider non-autonomous systems. SSK is a data-driven method that computes predictions as linear combinations of past outputs. To model the nonlinear dynamics of the system, we propose the kernel-based state-space kriging(K-SSK), a new version of the SSK where kernel functions are used instead of resorting to considerations about the locality of the data. Also, a Kalman filter can be used to improve the predictions at each time step in the case of noisy measurements. A constrained tracking nonlinear model predictive control(NMPC) scheme using the black-box input-output model obtained by means of the K-SSK prediction method is proposed. Finally, a simulation example and a real experiment are provided in order to assess the performance of the proposed controller.
基金supported by the National Natural Science Foundation of China(62173207,62003148)the China Postdoctoral Science Foundation(2021M691277)the Youth Innovation Team Project of Colleges and Universities in Shandong Province(2022KJ176)。
文摘Dear Editor,This letter investigates the fixed-time trajectory tracking controller design for nonholonomic chained systems with static state constraints.Firstly,a fixed-time tracking control law is given to carry out relay switching,which divides the controller development process into two stages.
基金supported in part by the National Natural Science Foundation of China(62072248,61902188)in part by China Postdoctoral Science Foundation(2019M651713)。
文摘With the deep combination of both modern information technology and traditional agriculture,the era of agriculture 4.0,which takes the form of smart agriculture,has come.Smart agriculture provides solutions for agricultural intelligence and automation.However,information security issues cannot be ignored with the development of agriculture brought by modern information technology.In this paper,three typical development modes of smart agriculture(precision agriculture,facility agriculture,and order agriculture)are presented.Then,7 key technologies and 11 key applications are derived from the above modes.Based on the above technologies and applications,6 security and privacy countermeasures(authentication and access control,privacy-preserving,blockchain-based solutions for data integrity,cryptography and key management,physical countermeasures,and intrusion detection systems)are summarized and discussed.Moreover,the security challenges of smart agriculture are analyzed and organized into two aspects:1)agricultural production,and 2)information technology.Most current research projects have not taken agricultural equipment as potential security threats.Therefore,we did some additional experiments based on solar insecticidal lamps Internet of Things,and the results indicate that agricultural equipment has an impact on agricultural security.Finally,more technologies(5 G communication,fog computing,Internet of Everything,renewable energy management system,software defined network,virtual reality,augmented reality,and cyber security datasets for smart agriculture)are described as the future research directions of smart agriculture.
文摘Vehicular communications and networking(VCN)is considered a billion-dollar industry.Its development not only possesses economic value,but also has enormous social potential.The earliest vehicular network started from the dedicated short range networks,such as the IEEE 802.11p standard established at the beginning of this century.In recent years,the public access network based VCN has been rapidly advanced.For example,LTE-V based on 4G LTE is under standardization。
基金supported by two research grants provided by the Karachi Institute of Economics and Technology(KIET)the Big Data Analytics Laboratory at the Insitute of Business Administration(IBAKarachi)。
文摘The advent of healthcare information management systems(HIMSs)continues to produce large volumes of healthcare data for patient care and compliance and regulatory requirements at a global scale.Analysis of this big data allows for boundless potential outcomes for discovering knowledge.Big data analytics(BDA)in healthcare can,for instance,help determine causes of diseases,generate effective diagnoses,enhance Qo S guarantees by increasing efficiency of the healthcare delivery and effectiveness and viability of treatments,generate accurate predictions of readmissions,enhance clinical care,and pinpoint opportunities for cost savings.However,BDA implementations in any domain are generally complicated and resource-intensive with a high failure rate and no roadmap or success strategies to guide the practitioners.In this paper,we present a comprehensive roadmap to derive insights from BDA in the healthcare(patient care)domain,based on the results of a systematic literature review.We initially determine big data characteristics for healthcare and then review BDA applications to healthcare in academic research focusing particularly on No SQL databases.We also identify the limitations and challenges of these applications and justify the potential of No SQL databases to address these challenges and further enhance BDA healthcare research.We then propose and describe a state-of-the-art BDA architecture called Med-BDA for healthcare domain which solves all current BDA challenges and is based on the latest zeta big data paradigm.We also present success strategies to ensure the working of Med-BDA along with outlining the major benefits of BDA applications to healthcare.Finally,we compare our work with other related literature reviews across twelve hallmark features to justify the novelty and importance of our work.The aforementioned contributions of our work are collectively unique and clearly present a roadmap for clinical administrators,practitioners and professionals to successfully implement BDA initiatives in their organizations.
