The Rural Minimum Living Standard Guarantee(Rural Dibao)is an important unconditional cash transfer program to alleviate poverty in rural China.Despite the importance of children’s nutrition in breaking poverty cycle...The Rural Minimum Living Standard Guarantee(Rural Dibao)is an important unconditional cash transfer program to alleviate poverty in rural China.Despite the importance of children’s nutrition in breaking poverty cycles,little is known about the impact of Rural Dibao on child nutrition outcomes.Using China Family Panel Studies(CFPS),this paper examines the effects of Rural Dibao on child nutrition outcomes and investigates potential pathways and heterogeneous effects.We exploit propensity score matching and difference-in-differences techniques to evaluate the effects of the Rural Dibao program on child nutrition outcomes.Our results suggest that Rural Dibao significantly impacts the nutrition outcomes of children up to 15 years of age.Specifically,our results suggest that Rural Dibao improves child height-to-age z-scores by 1.05 standard deviations and lowers the probability of stunting by 11.9 percentage points.Additional analyses suggest that increased protein intake is the main pathway through which Rural Dibao participation contributes to better nutrition outcomes.We also find that the effect of the program is more pronounced among girls,children who are non-left-behind or live with highly educated mothers,and those from low-income families and poor areas.Our findings suggest that Rural Dibao participation helps improve child nutrition outcomes through improving diet quality.展开更多
The growing development of the Internet of Things(IoT)is accelerating the emergence and growth of new IoT services and applications,which will result in massive amounts of data being generated,transmitted and pro-cess...The growing development of the Internet of Things(IoT)is accelerating the emergence and growth of new IoT services and applications,which will result in massive amounts of data being generated,transmitted and pro-cessed in wireless communication networks.Mobile Edge Computing(MEC)is a desired paradigm to timely process the data from IoT for value maximization.In MEC,a number of computing-capable devices are deployed at the network edge near data sources to support edge computing,such that the long network transmission delay in cloud computing paradigm could be avoided.Since an edge device might not always have sufficient resources to process the massive amount of data,computation offloading is significantly important considering the coop-eration among edge devices.However,the dynamic traffic characteristics and heterogeneous computing capa-bilities of edge devices challenge the offloading.In addition,different scheduling schemes might provide different computation delays to the offloaded tasks.Thus,offloading in mobile nodes and scheduling in the MEC server are coupled to determine service delay.This paper seeks to guarantee low delay for computation intensive applica-tions by jointly optimizing the offloading and scheduling in such an MEC system.We propose a Delay-Greedy Computation Offloading(DGCO)algorithm to make offloading decisions for new tasks in distributed computing-enabled mobile devices.A Reinforcement Learning-based Parallel Scheduling(RLPS)algorithm is further designed to schedule offloaded tasks in the multi-core MEC server.With an offloading delay broadcast mechanism,the DGCO and RLPS cooperate to achieve the goal of delay-guarantee-ratio maximization.Finally,the simulation results show that our proposal can bound the end-to-end delay of various tasks.Even under slightly heavy task load,the delay-guarantee-ratio given by DGCO-RLPS can still approximate 95%,while that given by benchmarked algorithms is reduced to intolerable value.The simulation results are demonstrated the effective-ness of DGCO-RLPS for delay guarantee in MEC.展开更多
The safety of agricultural industry in Hunan Province shows an upward trend from"basically safe"to"very safe",but the state in the"safe"or"very safe"range is still unstable.In v...The safety of agricultural industry in Hunan Province shows an upward trend from"basically safe"to"very safe",but the state in the"safe"or"very safe"range is still unstable.In view of this,Hunan Province should guarantee the agricultural production ability,cultivate and enhance the core competitiveness of agriculture,firmly grasp the agricultural control power,attach importance to the export quality of agri-cultural products and other aspects to ensure the safety of agricultural industry.展开更多
"The Maritime Silk Road", part of China's maritime power strategy, will safeguard the realization of "Chinese Dream". "The Maritime Silk Road" needs desperately legal guarantee of State's marine rights and int..."The Maritime Silk Road", part of China's maritime power strategy, will safeguard the realization of "Chinese Dream". "The Maritime Silk Road" needs desperately legal guarantee of State's marine rights and interest. The primary target of this paper is to put forward several suggestions on the legal guarantee of maritime rights protection based on analyzing the present situation of China legal system.展开更多
After summarizing researches on domestic and foreign tourism safety,it was found that there were few research results on mountainous tourism safety,especially tourism safety and tourism safety guarantee system of high...After summarizing researches on domestic and foreign tourism safety,it was found that there were few research results on mountainous tourism safety,especially tourism safety and tourism safety guarantee system of high and higher mountains with high risk.The paper had concluded hidden dangers and sources of safe accidents of mountainous tourism,and studied tourism safety guarantee system of high and higher mountains.Furthermore,it proposed that tourism safety guarantee system was composed of tourism safety policies and regulations,tourism precaution,tourism safety control,tourism safety rescue and tourism insurance;and finally pointed out components of each factor.展开更多
Although there are appropriate stipulations for the chattel guarantees in the law of China, this guarantee system could not adapt to the request of economy's development because of the following reasons: the scope...Although there are appropriate stipulations for the chattel guarantees in the law of China, this guarantee system could not adapt to the request of economy's development because of the following reasons: the scope of chattel guarantees is narrow according to relevant stipulations; the transaction cost of the chattel is high; mortgage registration of chattel is in a mess; lack of efficiently executive guarantee system, etc. To counter the problems existing in the present Chinese chattel guarantee system, in this article, the author proposed some corresponding suggestions and countermeasures, hoping to perfect the chattel guarantee system in China.展开更多
The decentralized robust guaranteed cost control problem is studied for a class of interconnected singular large-scale systems with time-delay and norm-bounded time-invariant parameter uncertainty under a given quadra...The decentralized robust guaranteed cost control problem is studied for a class of interconnected singular large-scale systems with time-delay and norm-bounded time-invariant parameter uncertainty under a given quadratic cost performance function. The problem that is addressed in this study is to design a decentralized robust guaranteed cost state feedback controller such that the closed-loop system is not only regular, impulse-free and stable, but also guarantees an adequate level of performance for all admissible uncertainties. A sufficient condition for the existence of the decentralized robust guaranteed cost state feedback controllers is proposed in terms of a linear matrix inequality (LMI) via LMI approach. When this condition is feasible, the desired state feedback decentralized robust guaranteed cost controller gain matrices can be obtained. Finally, an illustrative example is provided to demonstrate the effectiveness of the proposed approach.展开更多
This paper focuses on the problem of non-fragile guaranteed cost control for a class of T-S discrete-time fuzzy bilinear systems(DFBS).Based on the parallel distributed compensation(PDC) approach,the sufficient co...This paper focuses on the problem of non-fragile guaranteed cost control for a class of T-S discrete-time fuzzy bilinear systems(DFBS).Based on the parallel distributed compensation(PDC) approach,the sufficient conditions are derived such that the closed-loop system is asymptotically stable and the cost function value is no more than a certain upper bound in the presence of the additive controller gain perturbations.The non-fragile guaranteed cost controller can be obtained by solving a set of bilinear matrix inequalities(BMIs).The Van de Vusse model is utilized to demonstrate the validity and effectiveness of the proposed approach.展开更多
The problem of guaranteed cost active fault-tolerant controller (AFTC) design for networked control systems (NCSs) with both packet dropout and transmission delay is studied in this paper. Considering the packet d...The problem of guaranteed cost active fault-tolerant controller (AFTC) design for networked control systems (NCSs) with both packet dropout and transmission delay is studied in this paper. Considering the packet dropout and transmission delay, a piecewise constant controller is adopted. With a guaranteed cost function, optimal controllers whose number is equal to the number of actuators are designed, and the design process is formulated as a convex optimal problem that can be solved by existing software. The control strategy is proposed as follows: when actuator failures appear, the fault detection and isolation unit sends out the information to the controller choosing strategy, and then the optimal stabilizing controller with the smallest guaranteed cost value is chosen. Two illustrative examples are given to demonstrate the effectiveness of the proposed approach. By comparing with the existing methods, it can be seen that our method has a better performance.展开更多
The problem of guaranteed cost control for the networked control systems(NCSs) with time-varying delays, time-varying sampling intervals and signals quantization was investigated, wherein the physical plant was contin...The problem of guaranteed cost control for the networked control systems(NCSs) with time-varying delays, time-varying sampling intervals and signals quantization was investigated, wherein the physical plant was continuous-time one, and the control input was discrete-time one. By using an input delay approach and a sector bound method, the network induced delays, quantization parameter and sampling intervals were presented in one framework in the case of the state and the control input by quantized in a logarithmic form. A novel Lyapunov function with discontinuity, which took full advantages of the NCS characteristic information, was exploited. In addition, it was shown that Lyapunov function decreased at the jump instants. Furthermore, the Leibniz-Newton formula and free-weighting matrix methods were used to obtain the guaranteed cost controller design conditions which were dependent on the NCS characteristic information. A numerical example was used to illustrate the effectiveness of the proposed methods.展开更多
A guaranteed cost control problem for a class of linear discrete-time switched systems with norm-bounded uncertainties is considered in this article. The purpose is to construct a switching rule and design a state fee...A guaranteed cost control problem for a class of linear discrete-time switched systems with norm-bounded uncertainties is considered in this article. The purpose is to construct a switching rule and design a state feedback control law, such that, the closed-loop system is asymptotically stable and the closed-loop cost function value is not more than a specified upper bound for all admissible uncertainties under the constructed switching rule. A sufficient condition for the existence of guaranteed cost controllers and switching rules is derived based on the Lyapunov theory together with the linear matrix inequality (LMI) approach. Furthermore, a convex optimization problem with LMI constraints is formulated to select the suboptimal guaranteed cost controller. A numerical example demonstrates the validity of the proposed design approach.展开更多
The principles for lifecycle safety guarantee of engineering structures areproposed, and the conception is developed for developing the safety guarantee system by integratingthe monitoring system, analysis system and ...The principles for lifecycle safety guarantee of engineering structures areproposed, and the conception is developed for developing the safety guarantee system by integratingthe monitoring system, analysis system and maintenance system together on the basis of multi-sensor,distribution-measurement, data fusion and digital-signal-processor (DSP) technologies as well asthree-dimensional (3D) fatigue fracture unified theory. As all the systems should work in situs andin real-time, micromation and integration are important. Damage detectability is introduced toclarify the relationship of life prediction and healthy monitoring or faulty diagnosis. The researchwork to realize the lifecycle safety guarantee system is summarized and perspectives for futureefforts are outlined.展开更多
This paper focuses on the problem of non-fragile hybrid guaranteed cost control for a class of uncertain switched linear systems. The controller gain to be designed is assumed to have additive gain variations. Based o...This paper focuses on the problem of non-fragile hybrid guaranteed cost control for a class of uncertain switched linear systems. The controller gain to be designed is assumed to have additive gain variations. Based on multiple-Lyapunov function technique, the design of non-fragile hybrid guaranteed cost controllers is derived to make the corresponding closed-loop system asymptotically stable for all admissible uncertainties. Furthermore, a convex optimization approach with LMIs constraints is introduced to select the optimal non-fragile guaranteed cost controllers. Finally, a simulation example illustrates the effectiveness of the proposed approach.展开更多
To improve the energy efficiency of a direct expansion air conditioning(DX A/C) system while guaranteeing occupancy comfort, a hierarchical controller for a DX A/C system with uncertain parameters is proposed. The con...To improve the energy efficiency of a direct expansion air conditioning(DX A/C) system while guaranteeing occupancy comfort, a hierarchical controller for a DX A/C system with uncertain parameters is proposed. The control strategy consists of an open loop optimization controller and a closed-loop guaranteed cost periodically intermittent-switch controller(GCPISC). The error dynamics system of the closed-loop control is modelled based on the GCPISC principle. The difference,compared to the previous DX A/C system control methods, is that the controller designed in this paper performs control at discrete times. For the ease of designing the controller, a series of matrix inequalities are derived to be the sufficient conditions of the lower-layer closed-loop GCPISC controller. In this way, the DX A/C system output is derived to follow the optimal references obtained through the upper-layer open loop controller in exponential time, and the energy efficiency of the system is improved. Moreover, a static optimization problem is addressed for obtaining an optimal GCPISC law to ensure a minimum upper bound on the DX A/C system performance considering energy efficiency and output tracking error. The advantages of the designed hierarchical controller for a DX A/C system with uncertain parameters are demonstrated through some simulation results.展开更多
This paper focuses on robust control problems for supercavitating vehicles in the vertical plane. Firstly, for the mathematical model with mismatched uncertainties, the robust sliding mode function is designed based o...This paper focuses on robust control problems for supercavitating vehicles in the vertical plane. Firstly, for the mathematical model with mismatched uncertainties, the robust sliding mode function is designed based on the guaranteed cost theory, and a sufficient condition for the existence is given in terms of linear matrix inequality (LMI). Secondly, a continuous sliding mode controller is proposed to handle the nonlinear, time - varying behavior of the vehicles. Simulation results demonstrate that the system responds rapidly and has good robust stability. Therefore, it provides theoretical references for further study on control problems of supercavitating vehicles.展开更多
以往的法律英语翻译教学往往以术语解释和句子翻译练习为主,未能站在文本的高度俯瞰法律翻译的全过程,对文本在词汇、句法、语篇等层面的特征进行考量。本研究以法律文本Deed of Covenants and Guarantee为例,立足于对原文本的分析...以往的法律英语翻译教学往往以术语解释和句子翻译练习为主,未能站在文本的高度俯瞰法律翻译的全过程,对文本在词汇、句法、语篇等层面的特征进行考量。本研究以法律文本Deed of Covenants and Guarantee为例,立足于对原文本的分析,析出该法律文本的8类词汇特征,10类句法特征,以及4类语篇特征,旨在说明:法律翻译是理解与表这的过程,而实践中面对的翻译对象往往是文本,因而理解文本,析出文本各个层面的表现特征,就成为法律翻译的第一步。展开更多
With the quick development of the reform of College English teaching, web based College English teaching is used and generalized in every institution of higher education. However, more attention should be paid to the ...With the quick development of the reform of College English teaching, web based College English teaching is used and generalized in every institution of higher education. However, more attention should be paid to the teaching quality to develop this web based College English teaching model. Therefore, the construction of the quality guarantee system is of major significance to promote the effective design of web based College English course system and improve the quality of web based College English teaching.展开更多
End-to-end TCP (transmission control protocol) congestion control can cause unfairness among multiple TCP connections with different RTT (Round Trip Time). The throughput of TCP connection is inversely proportional to...End-to-end TCP (transmission control protocol) congestion control can cause unfairness among multiple TCP connections with different RTT (Round Trip Time). The throughput of TCP connection is inversely proportional to its RTT. To resolve this problem, researchers have proposed many methods. The existing proposals for RTT-aware conditioner work well when congestion level is low. However, they over-protect long RTT flows and starve short RTT flows when congestion level is high. Due to this reason, an improved method based on adaptive thought is proposed. According to the congestion level of networks, the mechanism can adaptively adjust the degree of the protection to long RTT flows. Extensive simulation experiments showed that the proposed mechanism can guarantee the bandwidth fairness of TCP flows effectively and outperforms the existing methods.展开更多
Decentralized production model of small peasant household is main threat for China food safety source. By using the advantage of farmer professional cooperative in controlling the quality of agricultural products,its ...Decentralized production model of small peasant household is main threat for China food safety source. By using the advantage of farmer professional cooperative in controlling the quality of agricultural products,its dilemma at the guarantee aspect of agricultural product quality safety is analyzed,and the guaranteeing measures of farmer professional cooperative for quality safety of agricultural products are proposed,which has an important significance for improving quality safety of agricultural products.展开更多
The risk points in the credit guarantee network of steel trade enterprises were identified by using the network analysis method in this paper. Firstly, the formation and operation mechanism of steel trade credit guara...The risk points in the credit guarantee network of steel trade enterprises were identified by using the network analysis method in this paper. Firstly, the formation and operation mechanism of steel trade credit guarantee network was analyzed.Secondly,a guarantee network was established to analyze the related network structure indexes based on the mutual guarantee data of 83 enterprises in a steel trade market. These indexes included centrality,honest broker,and structural hole. The results suggest that network analysis method can be used to find out the risk points of the guarantee network. Additionally,some recommendations are brought forth to reduce or prevent future crises.展开更多
基金The authors are grateful for support from the National Social Science Fund of China(21AJL015).
文摘The Rural Minimum Living Standard Guarantee(Rural Dibao)is an important unconditional cash transfer program to alleviate poverty in rural China.Despite the importance of children’s nutrition in breaking poverty cycles,little is known about the impact of Rural Dibao on child nutrition outcomes.Using China Family Panel Studies(CFPS),this paper examines the effects of Rural Dibao on child nutrition outcomes and investigates potential pathways and heterogeneous effects.We exploit propensity score matching and difference-in-differences techniques to evaluate the effects of the Rural Dibao program on child nutrition outcomes.Our results suggest that Rural Dibao significantly impacts the nutrition outcomes of children up to 15 years of age.Specifically,our results suggest that Rural Dibao improves child height-to-age z-scores by 1.05 standard deviations and lowers the probability of stunting by 11.9 percentage points.Additional analyses suggest that increased protein intake is the main pathway through which Rural Dibao participation contributes to better nutrition outcomes.We also find that the effect of the program is more pronounced among girls,children who are non-left-behind or live with highly educated mothers,and those from low-income families and poor areas.Our findings suggest that Rural Dibao participation helps improve child nutrition outcomes through improving diet quality.
基金supported in part by the National Natural Science Foundation of China under Grant 61901128,62273109the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(21KJB510032).
文摘The growing development of the Internet of Things(IoT)is accelerating the emergence and growth of new IoT services and applications,which will result in massive amounts of data being generated,transmitted and pro-cessed in wireless communication networks.Mobile Edge Computing(MEC)is a desired paradigm to timely process the data from IoT for value maximization.In MEC,a number of computing-capable devices are deployed at the network edge near data sources to support edge computing,such that the long network transmission delay in cloud computing paradigm could be avoided.Since an edge device might not always have sufficient resources to process the massive amount of data,computation offloading is significantly important considering the coop-eration among edge devices.However,the dynamic traffic characteristics and heterogeneous computing capa-bilities of edge devices challenge the offloading.In addition,different scheduling schemes might provide different computation delays to the offloaded tasks.Thus,offloading in mobile nodes and scheduling in the MEC server are coupled to determine service delay.This paper seeks to guarantee low delay for computation intensive applica-tions by jointly optimizing the offloading and scheduling in such an MEC system.We propose a Delay-Greedy Computation Offloading(DGCO)algorithm to make offloading decisions for new tasks in distributed computing-enabled mobile devices.A Reinforcement Learning-based Parallel Scheduling(RLPS)algorithm is further designed to schedule offloaded tasks in the multi-core MEC server.With an offloading delay broadcast mechanism,the DGCO and RLPS cooperate to achieve the goal of delay-guarantee-ratio maximization.Finally,the simulation results show that our proposal can bound the end-to-end delay of various tasks.Even under slightly heavy task load,the delay-guarantee-ratio given by DGCO-RLPS can still approximate 95%,while that given by benchmarked algorithms is reduced to intolerable value.The simulation results are demonstrated the effective-ness of DGCO-RLPS for delay guarantee in MEC.
基金Supported by Hunan Provincial Philosophy and Social Science Fund Project"Hunan Agricultural Industry Safety Assessment and Early Warning Research"(22YBA161).
文摘The safety of agricultural industry in Hunan Province shows an upward trend from"basically safe"to"very safe",but the state in the"safe"or"very safe"range is still unstable.In view of this,Hunan Province should guarantee the agricultural production ability,cultivate and enhance the core competitiveness of agriculture,firmly grasp the agricultural control power,attach importance to the export quality of agri-cultural products and other aspects to ensure the safety of agricultural industry.
文摘"The Maritime Silk Road", part of China's maritime power strategy, will safeguard the realization of "Chinese Dream". "The Maritime Silk Road" needs desperately legal guarantee of State's marine rights and interest. The primary target of this paper is to put forward several suggestions on the legal guarantee of maritime rights protection based on analyzing the present situation of China legal system.
基金Supported by Science and Technology Support Project of Sichuan Province(2009SZ0067)Key Research Subject of Soft Science Research Project of Sichuan Province(2009ZR0103)~~
文摘After summarizing researches on domestic and foreign tourism safety,it was found that there were few research results on mountainous tourism safety,especially tourism safety and tourism safety guarantee system of high and higher mountains with high risk.The paper had concluded hidden dangers and sources of safe accidents of mountainous tourism,and studied tourism safety guarantee system of high and higher mountains.Furthermore,it proposed that tourism safety guarantee system was composed of tourism safety policies and regulations,tourism precaution,tourism safety control,tourism safety rescue and tourism insurance;and finally pointed out components of each factor.
文摘Although there are appropriate stipulations for the chattel guarantees in the law of China, this guarantee system could not adapt to the request of economy's development because of the following reasons: the scope of chattel guarantees is narrow according to relevant stipulations; the transaction cost of the chattel is high; mortgage registration of chattel is in a mess; lack of efficiently executive guarantee system, etc. To counter the problems existing in the present Chinese chattel guarantee system, in this article, the author proposed some corresponding suggestions and countermeasures, hoping to perfect the chattel guarantee system in China.
基金This project was supported by the National Natural Science Foundation of China (60474078)Science Foundation of High Education of Jiangsu of China (04KJD120016).
文摘The decentralized robust guaranteed cost control problem is studied for a class of interconnected singular large-scale systems with time-delay and norm-bounded time-invariant parameter uncertainty under a given quadratic cost performance function. The problem that is addressed in this study is to design a decentralized robust guaranteed cost state feedback controller such that the closed-loop system is not only regular, impulse-free and stable, but also guarantees an adequate level of performance for all admissible uncertainties. A sufficient condition for the existence of the decentralized robust guaranteed cost state feedback controllers is proposed in terms of a linear matrix inequality (LMI) via LMI approach. When this condition is feasible, the desired state feedback decentralized robust guaranteed cost controller gain matrices can be obtained. Finally, an illustrative example is provided to demonstrate the effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(60374015)
文摘This paper focuses on the problem of non-fragile guaranteed cost control for a class of T-S discrete-time fuzzy bilinear systems(DFBS).Based on the parallel distributed compensation(PDC) approach,the sufficient conditions are derived such that the closed-loop system is asymptotically stable and the cost function value is no more than a certain upper bound in the presence of the additive controller gain perturbations.The non-fragile guaranteed cost controller can be obtained by solving a set of bilinear matrix inequalities(BMIs).The Van de Vusse model is utilized to demonstrate the validity and effectiveness of the proposed approach.
基金supported by National Outstanding Youth Foundation (No. 60525303)National Natural Science Foundation of China(No. 60704009)+1 种基金Key Project for Natural Science Research of Hebei Education Department (No. ZD200908)the Doctor Fund of YanShan University (No. B203)
文摘The problem of guaranteed cost active fault-tolerant controller (AFTC) design for networked control systems (NCSs) with both packet dropout and transmission delay is studied in this paper. Considering the packet dropout and transmission delay, a piecewise constant controller is adopted. With a guaranteed cost function, optimal controllers whose number is equal to the number of actuators are designed, and the design process is formulated as a convex optimal problem that can be solved by existing software. The control strategy is proposed as follows: when actuator failures appear, the fault detection and isolation unit sends out the information to the controller choosing strategy, and then the optimal stabilizing controller with the smallest guaranteed cost value is chosen. Two illustrative examples are given to demonstrate the effectiveness of the proposed approach. By comparing with the existing methods, it can be seen that our method has a better performance.
基金Project(61104106) supported by the National Natural Science Foundation of ChinaProject(201202156) supported by the Natural Science Foundation of Liaoning Province,ChinaProject(LJQ2012100) supported by Program for Liaoning Excellent Talents in University(LNET)
文摘The problem of guaranteed cost control for the networked control systems(NCSs) with time-varying delays, time-varying sampling intervals and signals quantization was investigated, wherein the physical plant was continuous-time one, and the control input was discrete-time one. By using an input delay approach and a sector bound method, the network induced delays, quantization parameter and sampling intervals were presented in one framework in the case of the state and the control input by quantized in a logarithmic form. A novel Lyapunov function with discontinuity, which took full advantages of the NCS characteristic information, was exploited. In addition, it was shown that Lyapunov function decreased at the jump instants. Furthermore, the Leibniz-Newton formula and free-weighting matrix methods were used to obtain the guaranteed cost controller design conditions which were dependent on the NCS characteristic information. A numerical example was used to illustrate the effectiveness of the proposed methods.
基金This project was supported by a Program for Changjiang Scholars and an Innovative Research Team in the University and the National Natural Science Foundation of P. R. China (60474015).
文摘A guaranteed cost control problem for a class of linear discrete-time switched systems with norm-bounded uncertainties is considered in this article. The purpose is to construct a switching rule and design a state feedback control law, such that, the closed-loop system is asymptotically stable and the closed-loop cost function value is not more than a specified upper bound for all admissible uncertainties under the constructed switching rule. A sufficient condition for the existence of guaranteed cost controllers and switching rules is derived based on the Lyapunov theory together with the linear matrix inequality (LMI) approach. Furthermore, a convex optimization problem with LMI constraints is formulated to select the suboptimal guaranteed cost controller. A numerical example demonstrates the validity of the proposed design approach.
基金This project is supported by National Natural Science Foundation of China (No.50275073)Space Science Foundation of China (No.03B52011).
文摘The principles for lifecycle safety guarantee of engineering structures areproposed, and the conception is developed for developing the safety guarantee system by integratingthe monitoring system, analysis system and maintenance system together on the basis of multi-sensor,distribution-measurement, data fusion and digital-signal-processor (DSP) technologies as well asthree-dimensional (3D) fatigue fracture unified theory. As all the systems should work in situs andin real-time, micromation and integration are important. Damage detectability is introduced toclarify the relationship of life prediction and healthy monitoring or faulty diagnosis. The researchwork to realize the lifecycle safety guarantee system is summarized and perspectives for futureefforts are outlined.
基金This work was supported by the National Natural Science Foundation of China (No.60274009, 60574013), and the Natural Science Foundation ofLiaoning Province(No.20032020).
文摘This paper focuses on the problem of non-fragile hybrid guaranteed cost control for a class of uncertain switched linear systems. The controller gain to be designed is assumed to have additive gain variations. Based on multiple-Lyapunov function technique, the design of non-fragile hybrid guaranteed cost controllers is derived to make the corresponding closed-loop system asymptotically stable for all admissible uncertainties. Furthermore, a convex optimization approach with LMIs constraints is introduced to select the optimal non-fragile guaranteed cost controllers. Finally, a simulation example illustrates the effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(61773220,61876192,61907021)the National Natural Science Foundation of Hubei(ZRMS2019000752)+2 种基金the Fundamental Research Funds for the Central Universities(2662018QD057,CZT20022,CZT20020)Academic Team in Universities(KTZ20051)School Talent Funds(YZZ19004)。
文摘To improve the energy efficiency of a direct expansion air conditioning(DX A/C) system while guaranteeing occupancy comfort, a hierarchical controller for a DX A/C system with uncertain parameters is proposed. The control strategy consists of an open loop optimization controller and a closed-loop guaranteed cost periodically intermittent-switch controller(GCPISC). The error dynamics system of the closed-loop control is modelled based on the GCPISC principle. The difference,compared to the previous DX A/C system control methods, is that the controller designed in this paper performs control at discrete times. For the ease of designing the controller, a series of matrix inequalities are derived to be the sufficient conditions of the lower-layer closed-loop GCPISC controller. In this way, the DX A/C system output is derived to follow the optimal references obtained through the upper-layer open loop controller in exponential time, and the energy efficiency of the system is improved. Moreover, a static optimization problem is addressed for obtaining an optimal GCPISC law to ensure a minimum upper bound on the DX A/C system performance considering energy efficiency and output tracking error. The advantages of the designed hierarchical controller for a DX A/C system with uncertain parameters are demonstrated through some simulation results.
基金Supported by the National Natural Science Foundation of China( No. 10802026) and Research Fund for the Doctoral Program of Higher Education of China ( No. 200802130003 ).
文摘This paper focuses on robust control problems for supercavitating vehicles in the vertical plane. Firstly, for the mathematical model with mismatched uncertainties, the robust sliding mode function is designed based on the guaranteed cost theory, and a sufficient condition for the existence is given in terms of linear matrix inequality (LMI). Secondly, a continuous sliding mode controller is proposed to handle the nonlinear, time - varying behavior of the vehicles. Simulation results demonstrate that the system responds rapidly and has good robust stability. Therefore, it provides theoretical references for further study on control problems of supercavitating vehicles.
文摘以往的法律英语翻译教学往往以术语解释和句子翻译练习为主,未能站在文本的高度俯瞰法律翻译的全过程,对文本在词汇、句法、语篇等层面的特征进行考量。本研究以法律文本Deed of Covenants and Guarantee为例,立足于对原文本的分析,析出该法律文本的8类词汇特征,10类句法特征,以及4类语篇特征,旨在说明:法律翻译是理解与表这的过程,而实践中面对的翻译对象往往是文本,因而理解文本,析出文本各个层面的表现特征,就成为法律翻译的第一步。
文摘With the quick development of the reform of College English teaching, web based College English teaching is used and generalized in every institution of higher education. However, more attention should be paid to the teaching quality to develop this web based College English teaching model. Therefore, the construction of the quality guarantee system is of major significance to promote the effective design of web based College English course system and improve the quality of web based College English teaching.
文摘End-to-end TCP (transmission control protocol) congestion control can cause unfairness among multiple TCP connections with different RTT (Round Trip Time). The throughput of TCP connection is inversely proportional to its RTT. To resolve this problem, researchers have proposed many methods. The existing proposals for RTT-aware conditioner work well when congestion level is low. However, they over-protect long RTT flows and starve short RTT flows when congestion level is high. Due to this reason, an improved method based on adaptive thought is proposed. According to the congestion level of networks, the mechanism can adaptively adjust the degree of the protection to long RTT flows. Extensive simulation experiments showed that the proposed mechanism can guarantee the bandwidth fairness of TCP flows effectively and outperforms the existing methods.
文摘Decentralized production model of small peasant household is main threat for China food safety source. By using the advantage of farmer professional cooperative in controlling the quality of agricultural products,its dilemma at the guarantee aspect of agricultural product quality safety is analyzed,and the guaranteeing measures of farmer professional cooperative for quality safety of agricultural products are proposed,which has an important significance for improving quality safety of agricultural products.
基金Social Science Programs Foundation of Ministry of Education of China(No.10YJA910002)
文摘The risk points in the credit guarantee network of steel trade enterprises were identified by using the network analysis method in this paper. Firstly, the formation and operation mechanism of steel trade credit guarantee network was analyzed.Secondly,a guarantee network was established to analyze the related network structure indexes based on the mutual guarantee data of 83 enterprises in a steel trade market. These indexes included centrality,honest broker,and structural hole. The results suggest that network analysis method can be used to find out the risk points of the guarantee network. Additionally,some recommendations are brought forth to reduce or prevent future crises.