Weighted factor is given to access eontrol policies to express the importanceof policy and its effect on access control decision. According to this weighted access controlframework, a trustworthiness model for aceess ...Weighted factor is given to access eontrol policies to express the importanceof policy and its effect on access control decision. According to this weighted access controlframework, a trustworthiness model for aceess request is also given. In this model, we give themeasure of trustworthiness factor to access request- by using some idea of uncertainty reasoning ofexpert system, present and prove the parallel propagation formula of request trustworthiness factoramong multiple policies, and get thefinal trustworthiness factor to decide whether authorizing. Inthis model, authorization decision is given according to the calculation of request trustworthinessfactor, which is more understandable, more suitable for real requirement and more powerfulforsecurity enhancement than traditional methods. Meanwhile the finer access control granularity isanother advantage.展开更多
Aiming at the tele-operation instability caused by time delay of interuet information transfer for internet based tele-robotics, this paper proposes a novel control framework for internet based tele-roboties, which ca...Aiming at the tele-operation instability caused by time delay of interuet information transfer for internet based tele-robotics, this paper proposes a novel control framework for internet based tele-roboties, which can guarantee the non-distortion-transfer of control information and reduce the difference of action time between the local simulated virtual robot and the remote real robot. This framework is insensitive to the inherent interact time delay, and differs from other tele-robotics systems that try to use some mathematic models to describe the internet delay or take some assumptions. In order to verify the framework, a 4-DOF fischertechnik industry robot tele-operation system has been developed using the new proposed framework. Experimental results demonstrate the applicable performance of the new framework. The framework is open structured and can be applied to other general purposed tele-operation systems.展开更多
Cloud computing is touted as the next big thing in the Information Technology (IT) industry, which is going to impact the businesses of any size and yet the security issue continues to pose a big threat on it. The sec...Cloud computing is touted as the next big thing in the Information Technology (IT) industry, which is going to impact the businesses of any size and yet the security issue continues to pose a big threat on it. The security and privacy issues persisting in cloud computing have proved to be an obstacle for its widespread adoption. In this paper, we look at these issues from a business perspective and how they are damaging the reputation of big companies. There is a literature review on the existing issues in cloud computing and how they are being tackled by the Cloud Service Providers (CSP). We propose a governing body framework which aims at solving these issues by establishing relationship amongst the CSPs in which the data about possible threats can be generated based on the previous attacks on other CSPs. The Governing Body will be responsible for Data Center control, Policy control, legal control, user awareness, performance evaluation, solution architecture and providing motivation for the entities involved.展开更多
Due to the current global oil price,the sand production is considered undesirable product and the control of sand production is considered as one of the main concerns of production engineers.It can damage downhole,sub...Due to the current global oil price,the sand production is considered undesirable product and the control of sand production is considered as one of the main concerns of production engineers.It can damage downhole,subsea equipments and surface production facilities,also increasing the risk of catastrophic failure.As a result of that it costs the producers multiple millions of dollars each year.Therefore,there are many different approaches of sand control designed for different reservoir conditions.Selecting an appropriate technique for preventing formation sand production depends on different reservoir parameters.Therefore,choosing the best sand control method is the result of systematic study.In this paper the sand production factors and their effects are presented where the emphasis is given towards the sand prediction to determine the probability of producing sand from the reservoir,followed by the correct prevention implementation of sand control method.The combination of these two is presented as a smart control framework that can be applied for sand production management.展开更多
The coordinate landing control of the unmanned aerial vehicles(UAVs)is a key technology to expand the cooperation between the UAVs and the unmanned surface vehicle(USV).This paper provides an eagle vision-based coordi...The coordinate landing control of the unmanned aerial vehicles(UAVs)is a key technology to expand the cooperation between the UAVs and the unmanned surface vehicle(USV).This paper provides an eagle vision-based coordinate landing control framework for the UAV swarm landing on a USV.Back-stepping controller is designed to guarantee that the tracking errors in both of the approaching stage and the landing stage converge to zero.Eagle vision is applied in the visual navigation to improve the landing accuracy.The experiment verified the feasibility of the proposed method.展开更多
In view of the currant status of the quality risk control of livestock products, the differences between the quality, safety and risk of the livestock products were pointed clearly; the derivative mechanism model of t...In view of the currant status of the quality risk control of livestock products, the differences between the quality, safety and risk of the livestock products were pointed clearly; the derivative mechanism model of the quality risk was studied; the risk system of livestock products was established; and the types of controllable risk were identified. On this basis, the design principles of risk control framework were established. Then the modular system of risk control was constructed and the attributes of production system were detailed into the describable indicators of risk control based on the thrae-dimensional risks.展开更多
We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of ...We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of the ions to create phonon-mediated entangling gates and,unlike the state of the art,requires neither weakcoupling Lamb-Dicke approximation nor perturbation treatment.With the application of gradient-based optimal control,it enables finding amplitude-and phase-modulated laser control protocols that work without the Lamb-Dicke approximation,promising gate speeds on the order of microseconds comparable to the characteristic trap frequencies.Also,robustness requirements on the temperature of the ions and initial optical phase can be conveniently included to pursue high-quality fast gates against experimental imperfections.Our approach represents a step in speeding up quantum gates to achieve larger quantum circuits for quantum computation and simulation,and thus can find applications in near-future experiments.展开更多
Water-soluble three-dimensional porous supramolecular organic frameworks（SOFs） have been demonstrated as a new generation of homogeneous polycationic platforms for anti-cancer drug delivery.The new SOF drug delivery...Water-soluble three-dimensional porous supramolecular organic frameworks（SOFs） have been demonstrated as a new generation of homogeneous polycationic platforms for anti-cancer drug delivery.The new SOF drug delivery systems（sof-DDSs） can adsorb dianionic pemetrexed（PMX）,a clinically used chemotherapeutic agent instantaneously upon dissolving in water,which is driven by both electrostatic attraction and hydrophobicity.The in situ-prepared PMX@SOFs are highly stable and can avoid important release of the drug during plasm circulation and overcome the multidrug resistance of human breast MCF-7/Adr cancer cells to enter the cancer cells.Acidic microenvironment of cancer cells promotes the release of the drug in cancer cells.Both in vitro and in vivo studies have revealed that sofDDSs considerably improve the treatment efficacy of PMX,leading to 6-12-fold reduction of the IC50 values,as compared with that of PMX alone.The new drug delivery strategy omits the loading process required by most of reported nanoparticle-based delivery systems and thus holds promise for future development of low-cost drug delivery systems展开更多
Initiated three decades ago,integrated design of controllers and fault detectors has continuously attracted research attention.The recent development of the unified control and detection framework with an observer-bas...Initiated three decades ago,integrated design of controllers and fault detectors has continuously attracted research attention.The recent development of the unified control and detection framework with an observer-based residual generator in its core gives a more general form of the previous works.Its applications to residual centred modelling of uncertain control systems,fault detection in feedback control systems with uncertainties,fault-tolerant control(FTC)as well as control performance degradation monitoring,detection and recovery are introduced.In conclusion,some future perspectives are proposed.展开更多
For the constant distance spacing policy,the existing researches of the string stability focus on the single-predecessor information framework（SPIF） and predecessor-successor information framework（PSIF）.The resear...For the constant distance spacing policy,the existing researches of the string stability focus on the single-predecessor information framework（SPIF） and predecessor-successor information framework（PSIF）.The research results demonstrated that the string stability could not be guaranteed with the SPIF,and then the PSIF was proposed to resolve this string instability.But the issue,whether the string stability can be guaranteed when applying the PSIF,is still controversial.Meanwhile,most of the previous researches on the string stability were conducted without consideration of the parasitic time delays and lags.In this paper,the practical longitudinal vehicle dynamics model is built with consideration of the parasitic time delays and lags existing in the actuators,sensors or the communication systems.Secondly,the detailed theoretical analysis of string stability in frequency domain is conducted to demonstrate that the classical linear control laws can not ensure the string stability when applying both the symmetrical PSIF（SPSIF） and asymmetrical PSIF（APSIF）.Thirdly,a control law,which adds the position and velocity information of the leading vehicle,is proposed to guarantee string stability for small/medium platoon,and the other control law,which adds the acceleration information of the controlled vehicle,is proposed to guarantee string stability for large platoon as well as small/medium platoon.Finally,the comparative simulation is conducted to confirm the conducted analysis and the proposed control laws.The conducted research completes the means to analyze the string stability in frequency domain,provides the parameters＇ reference for the design and implementation of the practical automatic following controllers,and improves the reliability and stability of the platoon of automatic vehicles.展开更多
It’s possible for malicious operators to seize hold of electrical control systems, for instance, the engine control unit of driverless vehicles, from various vectors, e.g. autonomic control system, remote vehicle acc...It’s possible for malicious operators to seize hold of electrical control systems, for instance, the engine control unit of driverless vehicles, from various vectors, e.g. autonomic control system, remote vehicle access, or human drivers. To mitigate potential risks, this paper provides the inauguration study by proposing a theoretical framework in the physical, human and cyber triad. Its goal is to, at each time point, detect adversary control behaviors and protect control systems against malicious operations via integrating a variety of methods. This paper only proposes a theoretical framework which tries to indicate possible threats. With the support of the framework, the security system can lightly reduce the risk. The development and implementation of the system are out of scope.展开更多
The research on legged robots attracted much attention both from the academia and industry. Legged robots are multi-input multi-output with multiple end-e ector systems. Therefore,the mechanical design and control fra...The research on legged robots attracted much attention both from the academia and industry. Legged robots are multi-input multi-output with multiple end-e ector systems. Therefore,the mechanical design and control framework are challenging issues. This paper reviews the development of type synthesis and behavior control on legged robots; introduces the hexapod robots developed in our research group based on the proposed type synthesis method. The control framework for legged robots includes data driven layer,robot behavior layer and robot execution layer. Each layer consists several components which are explained in details. Finally,various experiments were conducted on several hexapod robots. The summarization of the type synthesis and behavior control design constructed in this paper would provide a unified platform for communications and references for future advancement for legged robots.展开更多
Faults in traction system rectifiers can cause deterioration in system performance,robustness,and continuity.A single fault may propagate and cause the whole system to be shut down.Therefore,improving the robust stabi...Faults in traction system rectifiers can cause deterioration in system performance,robustness,and continuity.A single fault may propagate and cause the whole system to be shut down.Therefore,improving the robust stability and reliability of the control system is becoming more important.This study presents a robust current control based on a generalized internal model control(GIMC)for single-phase pulse width modulation(PWM)rectifier.The study aims to simultaneously achieve decent dynamic performance and robustness for the rectifiers under current sensor gain faults using generalized internal model control.H∞loop shaping can maintain robustness and achieve acceptable performance for the system in such cases.However,this controller will be conservative during an increase of sensor gain faults.That is,we sacrifice performance for robustness.Therefore,the GIMC structure is proposed to balance robustness and dynamic performance in such cases.The proposed control scheme during sensor gain faults is investigated.Furthermore,the robustness is analyzed using the v-gap metric.The proposed GIMC control framework consists of two parts,nominal and robustness controllers.The system is controlled solely by the nominal controller in normal operation in the absence of current sensor gain faults.If they occur,then the robustness controller will be active to maintain system robustness and achieve acceptable performance.The nominal controller is chosen as H∞loop shaping to assure nominal performance,while the robustness controller is chosen as the plant inverse cascaded by low pass filter to compensate for the sensor gain faults.Hardware-in-loop experimental results indicate that the suggested fault-tolerant control achieves good performance and robustness in comparison to the H∞loop shaping controller.展开更多
In this paper, a robust model predictive control approach is proposed for a class of uncertain systems with time-varying, linear fractional transformation perturbations. By adopting a sequence of feedback control laws...In this paper, a robust model predictive control approach is proposed for a class of uncertain systems with time-varying, linear fractional transformation perturbations. By adopting a sequence of feedback control laws instead of a single one, the control performance can be improved and the region of attraction can be enlarged compared with the existing model predictive control （MPC） approaches. Moreover, a synthesis approach of MPC is developed to achieve high performance with lower on-line computational burden. The effectiveness of the proposed approach is verified by simulation examples.展开更多
The command and control（C2） is a decision-making process based on human cognition,which contains operational,physical,and human characteristics,so it takes on uncertainty and complexity.As a decision support approac...The command and control（C2） is a decision-making process based on human cognition,which contains operational,physical,and human characteristics,so it takes on uncertainty and complexity.As a decision support approach,Bayesian networks（BNs） provide a framework in which a decision is made by combining the experts＇ knowledge and the specific data.In addition,an expert system represented by human cognitive framework is adopted to express the real-time decision-making process of the decision maker.The combination of the Bayesian decision support and human cognitive framework in the C2 of a specific application field is modeled and executed by colored Petri nets（CPNs）,and the consequences of execution manifest such combination can perfectly present the decision-making process in C2.展开更多
User’s data is considered as a vital asset of several organizations.Migrating data to the cloud computing is not an easy decision for any organization due to the privacy and security concerns.Service providers must e...User’s data is considered as a vital asset of several organizations.Migrating data to the cloud computing is not an easy decision for any organization due to the privacy and security concerns.Service providers must ensure that both data and applications that will be stored on the cloud should be protected in a secure environment.The data stored on the public cloud will be vulnerable to outside and inside attacks.This paper provides interactive multi-layer authentication frameworks for securing user identities on the cloud.Different access control policies are applied for verifying users on the cloud.A security mechanism is applied to the cloud application that includes user registration,granting user privileges,and generating user authentication factor.An intrusion detection system is embedded to the security mechanism to detect malicious users.The multi factor authentication,intrusion detection,and access control techniques can be used for ensuring the identity of the user.Finally,encryption techniques are used for protecting the data from being disclosed.Experimental results are carried out to verify the accuracy and efficiency of the proposed frameworks and mechanism.The results recorded high detection rate with low false positive alarms.展开更多
文摘Weighted factor is given to access eontrol policies to express the importanceof policy and its effect on access control decision. According to this weighted access controlframework, a trustworthiness model for aceess request is also given. In this model, we give themeasure of trustworthiness factor to access request- by using some idea of uncertainty reasoning ofexpert system, present and prove the parallel propagation formula of request trustworthiness factoramong multiple policies, and get thefinal trustworthiness factor to decide whether authorizing. Inthis model, authorization decision is given according to the calculation of request trustworthinessfactor, which is more understandable, more suitable for real requirement and more powerfulforsecurity enhancement than traditional methods. Meanwhile the finer access control granularity isanother advantage.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 60776816)Scientific Research Foundation of Education Department of Yunnan Province (Grant No.08Y10326)
文摘Aiming at the tele-operation instability caused by time delay of interuet information transfer for internet based tele-robotics, this paper proposes a novel control framework for internet based tele-roboties, which can guarantee the non-distortion-transfer of control information and reduce the difference of action time between the local simulated virtual robot and the remote real robot. This framework is insensitive to the inherent interact time delay, and differs from other tele-robotics systems that try to use some mathematic models to describe the internet delay or take some assumptions. In order to verify the framework, a 4-DOF fischertechnik industry robot tele-operation system has been developed using the new proposed framework. Experimental results demonstrate the applicable performance of the new framework. The framework is open structured and can be applied to other general purposed tele-operation systems.
文摘Cloud computing is touted as the next big thing in the Information Technology (IT) industry, which is going to impact the businesses of any size and yet the security issue continues to pose a big threat on it. The security and privacy issues persisting in cloud computing have proved to be an obstacle for its widespread adoption. In this paper, we look at these issues from a business perspective and how they are damaging the reputation of big companies. There is a literature review on the existing issues in cloud computing and how they are being tackled by the Cloud Service Providers (CSP). We propose a governing body framework which aims at solving these issues by establishing relationship amongst the CSPs in which the data about possible threats can be generated based on the previous attacks on other CSPs. The Governing Body will be responsible for Data Center control, Policy control, legal control, user awareness, performance evaluation, solution architecture and providing motivation for the entities involved.
文摘Due to the current global oil price,the sand production is considered undesirable product and the control of sand production is considered as one of the main concerns of production engineers.It can damage downhole,subsea equipments and surface production facilities,also increasing the risk of catastrophic failure.As a result of that it costs the producers multiple millions of dollars each year.Therefore,there are many different approaches of sand control designed for different reservoir conditions.Selecting an appropriate technique for preventing formation sand production depends on different reservoir parameters.Therefore,choosing the best sand control method is the result of systematic study.In this paper the sand production factors and their effects are presented where the emphasis is given towards the sand prediction to determine the probability of producing sand from the reservoir,followed by the correct prevention implementation of sand control method.The combination of these two is presented as a smart control framework that can be applied for sand production management.
基金partially supported by National Natural Science Foundation of China under Grants #U1913602,#U20B2071,#91948204 and #T2121003.
文摘The coordinate landing control of the unmanned aerial vehicles(UAVs)is a key technology to expand the cooperation between the UAVs and the unmanned surface vehicle(USV).This paper provides an eagle vision-based coordinate landing control framework for the UAV swarm landing on a USV.Back-stepping controller is designed to guarantee that the tracking errors in both of the approaching stage and the landing stage converge to zero.Eagle vision is applied in the visual navigation to improve the landing accuracy.The experiment verified the feasibility of the proposed method.
基金supported by the Science and Technology Development Plan Issue of Jinlin Province(20060217)
文摘In view of the currant status of the quality risk control of livestock products, the differences between the quality, safety and risk of the livestock products were pointed clearly; the derivative mechanism model of the quality risk was studied; the risk system of livestock products was established; and the types of controllable risk were identified. On this basis, the design principles of risk control framework were established. Then the modular system of risk control was constructed and the attributes of production system were detailed into the describable indicators of risk control based on the thrae-dimensional risks.
基金supported by the National Natural Science Foundation of China(Grant Nos.12441502,12122506,12204230,and 12404554)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2024ZD0300404)+6 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515020070)Shenzhen Science and Technology Program(Grant No.RCYX20200714114522109)China Postdoctoral Science Foundation(CPSF)(2024M762114)Postdoctoral Fellowship Program of CPSF(GZC20231727)supported by the National Natural Science Foundation of China(Grant Nos.92165206 and 11974330)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301603)the Fundamental Research Funds for the Central Universities。
文摘We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of the ions to create phonon-mediated entangling gates and,unlike the state of the art,requires neither weakcoupling Lamb-Dicke approximation nor perturbation treatment.With the application of gradient-based optimal control,it enables finding amplitude-and phase-modulated laser control protocols that work without the Lamb-Dicke approximation,promising gate speeds on the order of microseconds comparable to the characteristic trap frequencies.Also,robustness requirements on the temperature of the ions and initial optical phase can be conveniently included to pursue high-quality fast gates against experimental imperfections.Our approach represents a step in speeding up quantum gates to achieve larger quantum circuits for quantum computation and simulation,and thus can find applications in near-future experiments.
基金the National Natural Science Foundation of China(Nos.21432004,21529201,and 91527301)the Ministry of Science and Technology of China(No.2013CB834501)+1 种基金the Ministry of Education of China Research Fund for the Doctoral Program and of China for financial supportsupport from the Molecular Foundry,Lawrence Berkeley National Laboratory,supported by the Office of Science,Office of Basic Energy Sciences,Scientific User Facilities Division,of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231
文摘Water-soluble three-dimensional porous supramolecular organic frameworks（SOFs） have been demonstrated as a new generation of homogeneous polycationic platforms for anti-cancer drug delivery.The new SOF drug delivery systems（sof-DDSs） can adsorb dianionic pemetrexed（PMX）,a clinically used chemotherapeutic agent instantaneously upon dissolving in water,which is driven by both electrostatic attraction and hydrophobicity.The in situ-prepared PMX@SOFs are highly stable and can avoid important release of the drug during plasm circulation and overcome the multidrug resistance of human breast MCF-7/Adr cancer cells to enter the cancer cells.Acidic microenvironment of cancer cells promotes the release of the drug in cancer cells.Both in vitro and in vivo studies have revealed that sofDDSs considerably improve the treatment efficacy of PMX,leading to 6-12-fold reduction of the IC50 values,as compared with that of PMX alone.The new drug delivery strategy omits the loading process required by most of reported nanoparticle-based delivery systems and thus holds promise for future development of low-cost drug delivery systems
基金This work was supported by the National Natural Science Foundation of China(62020106003,62073029)the Beijing Natural Science Foundation(4202045)the Fundamental Research Funds for the Central Universities(FRF-TP-20-012A3).
文摘Initiated three decades ago,integrated design of controllers and fault detectors has continuously attracted research attention.The recent development of the unified control and detection framework with an observer-based residual generator in its core gives a more general form of the previous works.Its applications to residual centred modelling of uncertain control systems,fault detection in feedback control systems with uncertainties,fault-tolerant control(FTC)as well as control performance degradation monitoring,detection and recovery are introduced.In conclusion,some future perspectives are proposed.
基金supported by Doctoral Foundation of Ministry of Education of China (Grant No.20070006011)
文摘For the constant distance spacing policy,the existing researches of the string stability focus on the single-predecessor information framework（SPIF） and predecessor-successor information framework（PSIF）.The research results demonstrated that the string stability could not be guaranteed with the SPIF,and then the PSIF was proposed to resolve this string instability.But the issue,whether the string stability can be guaranteed when applying the PSIF,is still controversial.Meanwhile,most of the previous researches on the string stability were conducted without consideration of the parasitic time delays and lags.In this paper,the practical longitudinal vehicle dynamics model is built with consideration of the parasitic time delays and lags existing in the actuators,sensors or the communication systems.Secondly,the detailed theoretical analysis of string stability in frequency domain is conducted to demonstrate that the classical linear control laws can not ensure the string stability when applying both the symmetrical PSIF（SPSIF） and asymmetrical PSIF（APSIF）.Thirdly,a control law,which adds the position and velocity information of the leading vehicle,is proposed to guarantee string stability for small/medium platoon,and the other control law,which adds the acceleration information of the controlled vehicle,is proposed to guarantee string stability for large platoon as well as small/medium platoon.Finally,the comparative simulation is conducted to confirm the conducted analysis and the proposed control laws.The conducted research completes the means to analyze the string stability in frequency domain,provides the parameters＇ reference for the design and implementation of the practical automatic following controllers,and improves the reliability and stability of the platoon of automatic vehicles.
文摘It’s possible for malicious operators to seize hold of electrical control systems, for instance, the engine control unit of driverless vehicles, from various vectors, e.g. autonomic control system, remote vehicle access, or human drivers. To mitigate potential risks, this paper provides the inauguration study by proposing a theoretical framework in the physical, human and cyber triad. Its goal is to, at each time point, detect adversary control behaviors and protect control systems against malicious operations via integrating a variety of methods. This paper only proposes a theoretical framework which tries to indicate possible threats. With the support of the framework, the security system can lightly reduce the risk. The development and implementation of the system are out of scope.
基金Supported by National Natural Science Foundation of China(Grant No.U1613208)
文摘The research on legged robots attracted much attention both from the academia and industry. Legged robots are multi-input multi-output with multiple end-e ector systems. Therefore,the mechanical design and control framework are challenging issues. This paper reviews the development of type synthesis and behavior control on legged robots; introduces the hexapod robots developed in our research group based on the proposed type synthesis method. The control framework for legged robots includes data driven layer,robot behavior layer and robot execution layer. Each layer consists several components which are explained in details. Finally,various experiments were conducted on several hexapod robots. The summarization of the type synthesis and behavior control design constructed in this paper would provide a unified platform for communications and references for future advancement for legged robots.
基金supported by the National Natural Science Foundation of China(No.61733015)High-Speed Railway Joint Funds of the National Science Foundation of China(No.U1934204).
文摘Faults in traction system rectifiers can cause deterioration in system performance,robustness,and continuity.A single fault may propagate and cause the whole system to be shut down.Therefore,improving the robust stability and reliability of the control system is becoming more important.This study presents a robust current control based on a generalized internal model control(GIMC)for single-phase pulse width modulation(PWM)rectifier.The study aims to simultaneously achieve decent dynamic performance and robustness for the rectifiers under current sensor gain faults using generalized internal model control.H∞loop shaping can maintain robustness and achieve acceptable performance for the system in such cases.However,this controller will be conservative during an increase of sensor gain faults.That is,we sacrifice performance for robustness.Therefore,the GIMC structure is proposed to balance robustness and dynamic performance in such cases.The proposed control scheme during sensor gain faults is investigated.Furthermore,the robustness is analyzed using the v-gap metric.The proposed GIMC control framework consists of two parts,nominal and robustness controllers.The system is controlled solely by the nominal controller in normal operation in the absence of current sensor gain faults.If they occur,then the robustness controller will be active to maintain system robustness and achieve acceptable performance.The nominal controller is chosen as H∞loop shaping to assure nominal performance,while the robustness controller is chosen as the plant inverse cascaded by low pass filter to compensate for the sensor gain faults.Hardware-in-loop experimental results indicate that the suggested fault-tolerant control achieves good performance and robustness in comparison to the H∞loop shaping controller.
基金supported by National Natural Science Foundation of China (No. 60934007, No. 61074060)China Postdoctoral Science Foundation (No. 20090460627)+1 种基金Shanghai Postdoctoral Scientific Program (No. 10R21414600)China Postdoctoral Science Foundation Special Support (No. 201003272)
文摘In this paper, a robust model predictive control approach is proposed for a class of uncertain systems with time-varying, linear fractional transformation perturbations. By adopting a sequence of feedback control laws instead of a single one, the control performance can be improved and the region of attraction can be enlarged compared with the existing model predictive control （MPC） approaches. Moreover, a synthesis approach of MPC is developed to achieve high performance with lower on-line computational burden. The effectiveness of the proposed approach is verified by simulation examples.
基金supported by the National Natural Science Foundation of China (60874068)
文摘The command and control（C2） is a decision-making process based on human cognition,which contains operational,physical,and human characteristics,so it takes on uncertainty and complexity.As a decision support approach,Bayesian networks（BNs） provide a framework in which a decision is made by combining the experts＇ knowledge and the specific data.In addition,an expert system represented by human cognitive framework is adopted to express the real-time decision-making process of the decision maker.The combination of the Bayesian decision support and human cognitive framework in the C2 of a specific application field is modeled and executed by colored Petri nets（CPNs）,and the consequences of execution manifest such combination can perfectly present the decision-making process in C2.
文摘User’s data is considered as a vital asset of several organizations.Migrating data to the cloud computing is not an easy decision for any organization due to the privacy and security concerns.Service providers must ensure that both data and applications that will be stored on the cloud should be protected in a secure environment.The data stored on the public cloud will be vulnerable to outside and inside attacks.This paper provides interactive multi-layer authentication frameworks for securing user identities on the cloud.Different access control policies are applied for verifying users on the cloud.A security mechanism is applied to the cloud application that includes user registration,granting user privileges,and generating user authentication factor.An intrusion detection system is embedded to the security mechanism to detect malicious users.The multi factor authentication,intrusion detection,and access control techniques can be used for ensuring the identity of the user.Finally,encryption techniques are used for protecting the data from being disclosed.Experimental results are carried out to verify the accuracy and efficiency of the proposed frameworks and mechanism.The results recorded high detection rate with low false positive alarms.
