Conventional adaptive filtering algorithms often exhibit performance degradation when processing multipath interference in raw echoes of spaceborne synthetic aperture radar(SAR)systems due to anomalous outliers,manife...Conventional adaptive filtering algorithms often exhibit performance degradation when processing multipath interference in raw echoes of spaceborne synthetic aperture radar(SAR)systems due to anomalous outliers,manifesting as insufficient convergence and low estimation accuracy.To address this issue,this study proposes a novel robust adaptive filtering algorithm,namely the M-estimation-based minimum error entropy with affine projection(APMMEE)algorithm.This algorithm inherits the joint multi-data-block update mechanism of the affine projection algorithm,enabling rapid adaptation to the dynamic characteristics of raw echoes and achieving fast convergence.Meanwhile,it incorporates the M-estimation-based minimum error entropy(MMEE)criterion,which weights error samples in raw echoes through M-estimation functions,effectively suppressing outlier interference during the algorithm update.Both the system identification simulations and practical multipath interference suppression experiments using raw echoes demonstrate that the proposed APMMEE algorithm exhibits superior filtering performance.展开更多
This paper proposes an extension of the Modified-Plant ADRC(MP-ADRC)strategy to broaden its application to minimum phase dynamical systems.The main features of the MP-ADRC method are the inclusion of a constant gain i...This paper proposes an extension of the Modified-Plant ADRC(MP-ADRC)strategy to broaden its application to minimum phase dynamical systems.The main features of the MP-ADRC method are the inclusion of a constant gain in series with the plant output error and a linear filter in parallel with the overall error system.These structural changes do not influence the input/output dynamics of the original plant,but are intentionally introduced to modify the dynamics to be estimated by the extended state observer(ESO)and,thus,promote an increase in the robustness of the method.Some advantages can also be attributed to the proposed methodology,such as(i)the design procedures of both the controller and the ESO only require knowledge of the sign(±)of the plant input channel coefficient(or control gain);(ii)the plant control input is generated directly by a single ESO state variable.Despite the advantages and the characteristics of MP-ADRC mentioned earlier,closed-loop stability cannot be guaranteed when it is applied to dynamical systems that have finite zeros.To overcome this difficulty,this work introduces an extension in the MP-ADRC method.It basically consists of rewriting the minimum phase plant dynamics according to its relative order,and then follows with the design of the ESO by conveniently increasing the number of ESO state variables.The simulation results are also presented to illustrate the application of the proposed method.展开更多
This paper will investigate global exponential stability analysis for a class of switched positive nonlinear systems under minimum dwell time switching, whose nonlinear functions for each subsystem are constrained in ...This paper will investigate global exponential stability analysis for a class of switched positive nonlinear systems under minimum dwell time switching, whose nonlinear functions for each subsystem are constrained in a sector field by two odd symmetric piecewise linear functions and whose system matrices for each subsystem are Metzler. A class of multiple time-varying Lyapunov functions is constructed to obtain the computable sufficient conditions on the stability of such switched nonlinear systems within the framework of minimum dwell time switching.All present conditions can be solved by linear/nonlinear programming techniques. An example is provided to demonstrate the effectiveness of the proposed result.展开更多
Minimum-energy formation achievement problems for networked multiagent systems are investigated,where information networks with leaderless and leader-follower structures are respectively addressed and information netw...Minimum-energy formation achievement problems for networked multiagent systems are investigated,where information networks with leaderless and leader-follower structures are respectively addressed and information networks are randomly switching.The critical feature of this work is that the energy constraint is minimum in the sense of the linear matrix inequality,but limited-budget control and guaranteed-cost control cannot realize a minimum-energy formation.Firstly,the leaderless minimum-energy formation control problem is converted into an asymp-totic stability one via a nonsingular transformation and state space decomposition,and based on linear matrix inequality techniques,sufficient conditions for analysis and design of leaderless minimum-energy formation achievement are proposed,respectively,which can be solved by the generalized eigenvalue method.Then,main results of minimum-energy formation achievement of leaderless networked multiagent systems are extended leader-follower networked multiagent systems,where the asymmetric property of the leader-follower information network is well dealt with by two nonsingular transformations.Finally,two simulation examples are shown to verify the main results for minimum-energy formation achievements of leaderless and leader-follower networked multiagent systems,respectively.展开更多
An effective parameter in the miscible-CO_2 enhanced oil recovery procedure is the minimum miscibility pressure(MMP)defined as the lowest pressure that the oil in place and the injected gas into reservoir achieve misc...An effective parameter in the miscible-CO_2 enhanced oil recovery procedure is the minimum miscibility pressure(MMP)defined as the lowest pressure that the oil in place and the injected gas into reservoir achieve miscibility at a given temperature. Flue gases released from power plants can provide an available source of CO_2,which would otherwise be emitted to the atmosphere, for injection into a reservoir. However, the costs related to gas extraction from flue gases is potentially high. Hence, greater understanding the role of impurities in miscibility characteristics between CO_2 and reservoir fluids helps to establish which impurities are tolerable and which are not. In this study, we simulate the effects of the impurities nitrogen(N_2), methane(C_1), ethane(C_2) and propane(C_3) on CO_2 MMP. The simulation results reveal that,as an impurity, nitrogen increases CO_2–oil MMP more so than methane. On the other hand, increasing the propane(C_3)content can lead to a significant decrease in CO_2 MMP, whereas varying the concentrations of ethane(C_2) does not have a significant effect on the minimum miscibility pressure of reservoir crude oil and CO_2 gas. The novel relationships established are particularly valuable in circumstances where MMP experimental data are not available.展开更多
AIM To establish minimum clinically important difference(MCID) for measurements in an orthopaedic patient population with joint disorders.METHODS Adult patients aged 18 years and older seeking care for joint condition...AIM To establish minimum clinically important difference(MCID) for measurements in an orthopaedic patient population with joint disorders.METHODS Adult patients aged 18 years and older seeking care for joint conditions at an orthopaedic clinic took the Patient-Reported Outcomes Measurement Information System Physical Function(PROMIS~? PF) computerized adaptive test(CAT), hip disability and osteoarthritis outcome score for joint reconstruction(HOOS JR), and the knee injury and osteoarthritis outcome score for joint reconstruction(KOOS JR) from February 2014 to April 2017. MCIDs were calculated using anchorbased and distribution-based methods. Patient reports of meaningful change in function since their first clinic encounter were used as an anchor.RESULTS There were 2226 patients who participated with a mean age of 61.16(SD = 12.84) years, 41.6% male, and 89.7% Caucasian. Mean change ranged from 7.29 to 8.41 for the PROMIS~? PF CAT, from 14.81 to 19.68 for the HOOS JR, and from 14.51 to 18.85 for the KOOS JR. ROC cut-offs ranged from 1.97-8.18 for the PF CAT, 6.33-43.36 for the HOOS JR, and 2.21-8.16 for the KOOS JR. Distribution-based methods estimated MCID values ranging from 2.45 to 21.55 for the PROMIS~? PF CAT; from 3.90 to 43.61 for the HOOS JR, and from 3.98 to 40.67 for the KOOS JR. The median MCID value in the range was similar to the mean change score for each measure and was 7.9 for the PF CAT, 18.0 for the HOOS JR, and 15.1 for the KOOS JR.CONCLUSION This is the first comprehensive study providing a wide range of MCIDs for the PROMIS? PF, HOOS JR, and KOOS JR in orthopaedic patients with joint ailments.展开更多
Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmissio...Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmission.Earlier analysis of methods of pilot-aided channel estimation for ACM systems were relatively little.In this paper,we investigate the performance of CSI prediction using the Minimum Mean Square Error(MMSE)channel estimator for an ACM system.To solve the two problems of MMSE:high computational operations and oversimplified assumption,we then propose the Low-Complexity schemes(LC-MMSE and Recursion LC-MMSE(R-LC-MMSE)).Computational complexity and Mean Square Error(MSE) are presented to evaluate the efficiency of the proposed algorithm.Both analysis and numerical results show that LC-MMSE performs close to the wellknown MMSE estimator with much lower complexity and R-LC-MMSE improves the application of MMSE estimation to specific circumstances.展开更多
In distributed cloud storage systems, inevitably there exist multiple node failures at the same time. The existing methods of regenerating codes, including minimum storage regenerating(MSR) codes and minimum bandwidth...In distributed cloud storage systems, inevitably there exist multiple node failures at the same time. The existing methods of regenerating codes, including minimum storage regenerating(MSR) codes and minimum bandwidth regenerating(MBR) codes, are mainly to repair one single or several failed nodes, unable to meet the repair need of distributed cloud storage systems. In this paper, we present locally minimum storage regenerating(LMSR) codes to recover multiple failed nodes at the same time. Specifically, the nodes in distributed cloud storage systems are divided into multiple local groups, and in each local group(4, 2) or(5, 3) MSR codes are constructed. Moreover, the grouping method of storage nodes and the repairing process of failed nodes in local groups are studied. Theoretical analysis shows that LMSR codes can achieve the same storage overhead as MSR codes. Furthermore, we verify by means of simulation that, compared with MSR codes, LMSR codes can reduce the repair bandwidth and disk I/O overhead effectively.展开更多
In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem i...In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem is formulated under the constraints of maximum power and minimum rate of each user.Then,we develop a near-optimal power allocation(PA)scheme by using the successive convex approximation(SCA)method,Lagrange multiplier method,and block coordinate descent(BCD)method,and it can obtain almost the same SE as the benchmark scheme with lower complexity.Since this scheme needs three-layer iteration,a suboptimal PA scheme is developed to further reduce the complexity,where the characteristic of massive MIMO(i.e.,numerous receive antennas)is utilized for convex reformulation,and the rate constraint is converted to linear constraints.This suboptimal scheme only needs single-layer iteration,thus has lower complexity than the near-optimal scheme.Finally,we joint design the pilot power and data power to further improve the performance,and propose an two-stage algorithm to obtain joint PA.Simulation results verify the effectiveness of the proposed schemes,and superior SE performance is achieved.展开更多
This paper investigates the anomaly-resistant decentralized state estimation(SE) problem for a class of wide-area power systems which are divided into several non-overlapping areas connected through transmission lines...This paper investigates the anomaly-resistant decentralized state estimation(SE) problem for a class of wide-area power systems which are divided into several non-overlapping areas connected through transmission lines. Two classes of measurements(i.e., local measurements and edge measurements) are obtained, respectively, from the individual area and the transmission lines. A decentralized state estimator, whose performance is resistant against measurement with anomalies, is designed based on the minimum error entropy with fiducial points(MEEF) criterion. Specifically, 1) An augmented model, which incorporates the local prediction and local measurement, is developed by resorting to the unscented transformation approach and the statistical linearization approach;2) Using the augmented model, an MEEF-based cost function is designed that reflects the local prediction errors of the state and the measurement;and 3) The local estimate is first obtained by minimizing the MEEF-based cost function through a fixed-point iteration and then updated by using the edge measuring information. Finally, simulation experiments with three scenarios are carried out on the IEEE 14-bus system to illustrate the validity of the proposed anomaly-resistant decentralized SE scheme.展开更多
In this paper, an output-feedback tracking controller is proposed for a class of nonlinear non-minimum phase systems.To keep the unstable internal dynamics bounded, the method of output redefinition is applied to let ...In this paper, an output-feedback tracking controller is proposed for a class of nonlinear non-minimum phase systems.To keep the unstable internal dynamics bounded, the method of output redefinition is applied to let the stability of the internal dynamics depend on that of redefined output, thus we only need to consider the new external dynamics rather than internal dynamics in the process of designing control law. To overcome the explosion of complexity problem in traditional backstepping design, the dynamic surface control(DSC) method is firstly used to deal with the problem of tracking control for the nonlinear non-minimum phase systems. The proposed outputfeedback DSC controller not only forces the system output to asymptotically track the desired trajectory, but also drives the unstable internal dynamics to follow its corresponding bounded and causal ideal internal dynamics, which is solved via stable system center method. Simulation results illustrate the validity of the proposed output-feedback DSC controller.展开更多
This paper uses SWOT analysis, feasibility analysis of integration of urban and rural residents in China, including the overall analysis of the urban and rural integration China internal conditions, mainly for its ove...This paper uses SWOT analysis, feasibility analysis of integration of urban and rural residents in China, including the overall analysis of the urban and rural integration China internal conditions, mainly for its overall advantages and disadvantages are analyzed; and the external environment, the system is mainly to raise the opportunities and threats were analyzed; in these. The external conditions are analyzed based on the construction of SWOT strategic matrix, found the advantages and disadvantages of the reform process of the integration of urban and rural subsistence allowances system in coexist, opportunities outweigh the challenges, so China＇s overall urban and rural integration construction is feasible.展开更多
Active disturbance rejection control （ADRC）, as proposed by Prof. Jingqing Han, reduces first the plant dynamics to its canonical form, normally in the form of cascade integrators, for which the standard controller ...Active disturbance rejection control （ADRC）, as proposed by Prof. Jingqing Han, reduces first the plant dynamics to its canonical form, normally in the form of cascade integrators, for which the standard controller can be employed to meet the design specifications. This paper concerns with the selection of the canonical form for non-minimum phase systems. In particular, it is shown that, by employing the well known controllable canonical form, the uncertainties of such systems can be divided into two terms in the state space model, one in the control channel and the other in the output channel. The necessary and sufficient condition is obtained for the stability of the closed-loop system with the proposed canonical form and ADRC. Also, by showing the necessity of the detectability of the extended system as well as certain information of the system-s ＂zeros＂, we present the fundamental guidelines of design ADRC for non-minimum phase uncertain systems.展开更多
This paper concerns minimum-energy leader-following formation design and analysis problems of distributed multiagent systems(DMASs)subjected to randomly switching topologies and aperiodic communication pauses.The crit...This paper concerns minimum-energy leader-following formation design and analysis problems of distributed multiagent systems(DMASs)subjected to randomly switching topologies and aperiodic communication pauses.The critical feature of this paper is that the energy consumption during the formation control process is restricted by the minimum-energy constraint in the sense of the linear matrix inequality.Firstly,the leader-following formation control protocol is proposed based on the relative state information of neighboring agents,where the total energy consumption is considered.Then,minimum-energy leader-following formation design and analysis criteria are presented in the form of the linear matrix inequality,which can be checked by the generalized eigenvalue method.Especially,the value of the minimum-energy constraint is determined.An illustrative simulation is provided to show the effectiveness of the main results.展开更多
Based on the conclusion of the related researches on China's rural poverty alleviation policies and poverty problems,studies of Chinese scholars on the convergence between rural minimum subsistence system and the ...Based on the conclusion of the related researches on China's rural poverty alleviation policies and poverty problems,studies of Chinese scholars on the convergence between rural minimum subsistence system and the development policies of poverty alleviation are illustrated and personal understandings proposed.On the one hand,considering the actual situations of the quickening of China's urbanization and deepening of poverty,it is necessary to make significant adjustment and transformation in China's poverty reduction policies and minimum subsistence security system.On the other hand,it is pointed out that there is no omnipotent experience to follow in the convergence of minimum subsistence security system and poverty reduction policies.The actual conditions in various regions should be taken into consideration.And it is suggested that China should achieve the organic integration of rural minimum subsistence security system and poverty alleviation policies from management,capital and policy.展开更多
In this study, numerical analysis is performed to adopt the equivalence ratio on the high velocity oxygen fuel （HVOF） thermal spray coating systems equipped with a minimum length nozzle. The analysis is applied to i...In this study, numerical analysis is performed to adopt the equivalence ratio on the high velocity oxygen fuel （HVOF） thermal spray coating systems equipped with a minimum length nozzle. The analysis is applied to investigate the axisymmetric, steady-state, turbulent, and chemically combusting flow both within the torch and in a free jet region between the torch and the substrate to be coated. The combustion is modeled using a single-step and eddy-dissipation model which assumes that the reaction rate is limited by the turbulent mixing rate of the fuel and oxidant. As the diameter of the nozzle throat is increased, the location of the Mach shock disc moves backward from the nozzle exit. As the throat diameter and the divergent portion are 6 mm and 8 mm, respectively, the pressure in the HVOF system is the lowest at the chamber and the expanding gas is steadily maintained with both high velocity and high temperature for different equivalence ratios. Thus, relatively minor amendments of the equivalence ratio and the geometry of HVOF can lead to improved control over coating characteristics.展开更多
This paper investigates the consensus control of multi-agent systems(MASs) with constrained input using the dynamic event-triggered mechanism(ETM).Consider the MASs with small-scale networks where a centralized dynami...This paper investigates the consensus control of multi-agent systems(MASs) with constrained input using the dynamic event-triggered mechanism(ETM).Consider the MASs with small-scale networks where a centralized dynamic ETM with global information of the MASs is first designed.Then,a distributed dynamic ETM which only uses local information is developed for the MASs with large-scale networks.It is shown that the semi-global consensus of the MASs can be achieved by the designed bounded control protocol where the Zeno phenomenon is eliminated by a designable minimum inter-event time.In addition,it is easier to find a trade-off between the convergence rate and the minimum inter-event time by an adjustable parameter.Furthermore,the results are extended to regional consensus of the MASs with the bounded control protocol.Numerical simulations show the effectiveness of the proposed approach.展开更多
New method for determination of optimal placement and value of installed capacity of renewable source of energy (RES) by the criterion of minimum losses of active power, that allows taking into consideration the depen...New method for determination of optimal placement and value of installed capacity of renewable source of energy (RES) by the criterion of minimum losses of active power, that allows taking into consideration the dependence of RES on natural conditions of region, schedule of energy supply, parameters and configuration of distribution network is suggested in the paper. Results of computations of test scheme confirm the efficiency of the proposed method and its simplicity as compared with the methods considered in literature sources.展开更多
An accurate and reliable estimation of minimum miscibility pressure(MMP) of CO2-oil system is a critical task for the design and implementation of CO2 miscible displacement process.In this study,an improved CO2-oil MM...An accurate and reliable estimation of minimum miscibility pressure(MMP) of CO2-oil system is a critical task for the design and implementation of CO2 miscible displacement process.In this study,an improved CO2-oil MMP correlation was developed to predict the MMP values for both pure and impure CO2 injection cases based on ten influential factors,i.e.reservoir temperature(TR),molecular weight of C7+oil components(MWC7+),mole fraction of volatile oil components(xvol),mole fraction of C2-C4 oil components(xC2-C4),mole fraction of C5-C6 oil components(xCs-5-C6),and the gas stream mole fractions of CO2(yCO2),H2S(yH2S),C1(yC1),hydrocarbons(yHC)and N2(yN2).The accuracy of the improved correlation was evaluated against experimental data reported in literature concurrently with those estimated by several renowned correlations.It was found that the improved correlation provided higher prediction accuracy and consistency with literature experimental data than other literature correlations.In addition,the predictive capability of the improved correlation was further validated by predicting an experimentally measured CO2-Oil MMP data,and it showed an accurate result with the absolute deviation of 4.15%.Besides,the differential analysis of the improved correlation was analyzed to estimate the impact of parameters uncertainty in the original MMP data on the calculated results.Also,sensitivity analysis was performed to analyze the influence of each parameter on MMP qualitatively and quantitatively.The results revealed that the increase of xC2-C4,xC5-C6 and yH2 S lead to the decrease of MMP,while the increase of TR,MWC7+,xvol,yCO2,YC1,yHC and yN2 tend to increase the MMP.Overall,the relevance of each parameter with MMP follows the order of TR> xC5-C6> MWC7+> xvol> yH2 S> yHC> yCO2>yC1>yN2>xC2-C4.展开更多
The surplus rural labors transferring to the city is an inevitable trend in the economic development of the reform and opening up. The household register system has made urban migrant workers free from the social secu...The surplus rural labors transferring to the city is an inevitable trend in the economic development of the reform and opening up. The household register system has made urban migrant workers free from the social security system and drift on the brink of city. Social assistance system concerning their interests is few. This article starts with the current situation of rural migrant workers in social assistance system, states the necessity and feasibility for bringing the migrant workers into the urban minimum living security system and according to the characteristics of the migrant workers on the reasonable classification, finally talks about existing obstacles and countermeasures of the migrant workers joining into the urban low income system. I believe that with the continuous reform of the registered permanent household register system, the continuous development of urbanization, the basic life of migrant worker will be guaranteed.展开更多
基金supported by Shandong Provincial Natural Science Foundation(No.ZR2022MF314).
文摘Conventional adaptive filtering algorithms often exhibit performance degradation when processing multipath interference in raw echoes of spaceborne synthetic aperture radar(SAR)systems due to anomalous outliers,manifesting as insufficient convergence and low estimation accuracy.To address this issue,this study proposes a novel robust adaptive filtering algorithm,namely the M-estimation-based minimum error entropy with affine projection(APMMEE)algorithm.This algorithm inherits the joint multi-data-block update mechanism of the affine projection algorithm,enabling rapid adaptation to the dynamic characteristics of raw echoes and achieving fast convergence.Meanwhile,it incorporates the M-estimation-based minimum error entropy(MMEE)criterion,which weights error samples in raw echoes through M-estimation functions,effectively suppressing outlier interference during the algorithm update.Both the system identification simulations and practical multipath interference suppression experiments using raw echoes demonstrate that the proposed APMMEE algorithm exhibits superior filtering performance.
基金supported in part by the Brazilian research agencies CNPq and CAPESby the Fundação Carlos Chagas Filho de AmparoàPesquisa do Estado do Rio de Janeiro,FAPERJ-Brasil(Project E-26/210.425/2024).
文摘This paper proposes an extension of the Modified-Plant ADRC(MP-ADRC)strategy to broaden its application to minimum phase dynamical systems.The main features of the MP-ADRC method are the inclusion of a constant gain in series with the plant output error and a linear filter in parallel with the overall error system.These structural changes do not influence the input/output dynamics of the original plant,but are intentionally introduced to modify the dynamics to be estimated by the extended state observer(ESO)and,thus,promote an increase in the robustness of the method.Some advantages can also be attributed to the proposed methodology,such as(i)the design procedures of both the controller and the ESO only require knowledge of the sign(±)of the plant input channel coefficient(or control gain);(ii)the plant control input is generated directly by a single ESO state variable.Despite the advantages and the characteristics of MP-ADRC mentioned earlier,closed-loop stability cannot be guaranteed when it is applied to dynamical systems that have finite zeros.To overcome this difficulty,this work introduces an extension in the MP-ADRC method.It basically consists of rewriting the minimum phase plant dynamics according to its relative order,and then follows with the design of the ESO by conveniently increasing the number of ESO state variables.The simulation results are also presented to illustrate the application of the proposed method.
基金supported by the National Natural Science Foundation of China(61673198)the Provincial Natural Science Foundation of Liaoning Province(20180550473)
文摘This paper will investigate global exponential stability analysis for a class of switched positive nonlinear systems under minimum dwell time switching, whose nonlinear functions for each subsystem are constrained in a sector field by two odd symmetric piecewise linear functions and whose system matrices for each subsystem are Metzler. A class of multiple time-varying Lyapunov functions is constructed to obtain the computable sufficient conditions on the stability of such switched nonlinear systems within the framework of minimum dwell time switching.All present conditions can be solved by linear/nonlinear programming techniques. An example is provided to demonstrate the effectiveness of the proposed result.
基金supported by the National Natural Science Foundation of China(Nos.62176263,62103434,62003363,61703411)the Science Foundation for Distinguished Youth of Shaanxi Province,China(No.2021JC-35)+2 种基金the Youth Science Foundation of Shaanxi Province,China(No.2021JQ-375)the China Postdoctoral Science Special Foundation(No.2021T140790)the China Postdoctoral Science Foundation(No.271004).
文摘Minimum-energy formation achievement problems for networked multiagent systems are investigated,where information networks with leaderless and leader-follower structures are respectively addressed and information networks are randomly switching.The critical feature of this work is that the energy constraint is minimum in the sense of the linear matrix inequality,but limited-budget control and guaranteed-cost control cannot realize a minimum-energy formation.Firstly,the leaderless minimum-energy formation control problem is converted into an asymp-totic stability one via a nonsingular transformation and state space decomposition,and based on linear matrix inequality techniques,sufficient conditions for analysis and design of leaderless minimum-energy formation achievement are proposed,respectively,which can be solved by the generalized eigenvalue method.Then,main results of minimum-energy formation achievement of leaderless networked multiagent systems are extended leader-follower networked multiagent systems,where the asymmetric property of the leader-follower information network is well dealt with by two nonsingular transformations.Finally,two simulation examples are shown to verify the main results for minimum-energy formation achievements of leaderless and leader-follower networked multiagent systems,respectively.
文摘An effective parameter in the miscible-CO_2 enhanced oil recovery procedure is the minimum miscibility pressure(MMP)defined as the lowest pressure that the oil in place and the injected gas into reservoir achieve miscibility at a given temperature. Flue gases released from power plants can provide an available source of CO_2,which would otherwise be emitted to the atmosphere, for injection into a reservoir. However, the costs related to gas extraction from flue gases is potentially high. Hence, greater understanding the role of impurities in miscibility characteristics between CO_2 and reservoir fluids helps to establish which impurities are tolerable and which are not. In this study, we simulate the effects of the impurities nitrogen(N_2), methane(C_1), ethane(C_2) and propane(C_3) on CO_2 MMP. The simulation results reveal that,as an impurity, nitrogen increases CO_2–oil MMP more so than methane. On the other hand, increasing the propane(C_3)content can lead to a significant decrease in CO_2 MMP, whereas varying the concentrations of ethane(C_2) does not have a significant effect on the minimum miscibility pressure of reservoir crude oil and CO_2 gas. The novel relationships established are particularly valuable in circumstances where MMP experimental data are not available.
基金National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health,No.U01AR067138.
文摘AIM To establish minimum clinically important difference(MCID) for measurements in an orthopaedic patient population with joint disorders.METHODS Adult patients aged 18 years and older seeking care for joint conditions at an orthopaedic clinic took the Patient-Reported Outcomes Measurement Information System Physical Function(PROMIS~? PF) computerized adaptive test(CAT), hip disability and osteoarthritis outcome score for joint reconstruction(HOOS JR), and the knee injury and osteoarthritis outcome score for joint reconstruction(KOOS JR) from February 2014 to April 2017. MCIDs were calculated using anchorbased and distribution-based methods. Patient reports of meaningful change in function since their first clinic encounter were used as an anchor.RESULTS There were 2226 patients who participated with a mean age of 61.16(SD = 12.84) years, 41.6% male, and 89.7% Caucasian. Mean change ranged from 7.29 to 8.41 for the PROMIS~? PF CAT, from 14.81 to 19.68 for the HOOS JR, and from 14.51 to 18.85 for the KOOS JR. ROC cut-offs ranged from 1.97-8.18 for the PF CAT, 6.33-43.36 for the HOOS JR, and 2.21-8.16 for the KOOS JR. Distribution-based methods estimated MCID values ranging from 2.45 to 21.55 for the PROMIS~? PF CAT; from 3.90 to 43.61 for the HOOS JR, and from 3.98 to 40.67 for the KOOS JR. The median MCID value in the range was similar to the mean change score for each measure and was 7.9 for the PF CAT, 18.0 for the HOOS JR, and 15.1 for the KOOS JR.CONCLUSION This is the first comprehensive study providing a wide range of MCIDs for the PROMIS? PF, HOOS JR, and KOOS JR in orthopaedic patients with joint ailments.
基金supported by the 2011 China Aerospace Science and Technology Foundationthe Certain Ministry Foundation under Grant No.20212HK03010
文摘Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmission.Earlier analysis of methods of pilot-aided channel estimation for ACM systems were relatively little.In this paper,we investigate the performance of CSI prediction using the Minimum Mean Square Error(MMSE)channel estimator for an ACM system.To solve the two problems of MMSE:high computational operations and oversimplified assumption,we then propose the Low-Complexity schemes(LC-MMSE and Recursion LC-MMSE(R-LC-MMSE)).Computational complexity and Mean Square Error(MSE) are presented to evaluate the efficiency of the proposed algorithm.Both analysis and numerical results show that LC-MMSE performs close to the wellknown MMSE estimator with much lower complexity and R-LC-MMSE improves the application of MMSE estimation to specific circumstances.
基金supported in part by the National Natural Science Foundation of China (61640006, 61572188)the Natural Science Foundation of Shaanxi Province, China (2015JM6307, 2016JQ6011)the project of science and technology of Xi’an City (2017088CG/RC051(CADX002))
文摘In distributed cloud storage systems, inevitably there exist multiple node failures at the same time. The existing methods of regenerating codes, including minimum storage regenerating(MSR) codes and minimum bandwidth regenerating(MBR) codes, are mainly to repair one single or several failed nodes, unable to meet the repair need of distributed cloud storage systems. In this paper, we present locally minimum storage regenerating(LMSR) codes to recover multiple failed nodes at the same time. Specifically, the nodes in distributed cloud storage systems are divided into multiple local groups, and in each local group(4, 2) or(5, 3) MSR codes are constructed. Moreover, the grouping method of storage nodes and the repairing process of failed nodes in local groups are studied. Theoretical analysis shows that LMSR codes can achieve the same storage overhead as MSR codes. Furthermore, we verify by means of simulation that, compared with MSR codes, LMSR codes can reduce the repair bandwidth and disk I/O overhead effectively.
基金supported by the Fundamental Research Funds for the Central Universities of NUAA(No.kfjj20200414)Natural Science Foundation of Jiangsu Province in China(No.BK20181289).
文摘In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem is formulated under the constraints of maximum power and minimum rate of each user.Then,we develop a near-optimal power allocation(PA)scheme by using the successive convex approximation(SCA)method,Lagrange multiplier method,and block coordinate descent(BCD)method,and it can obtain almost the same SE as the benchmark scheme with lower complexity.Since this scheme needs three-layer iteration,a suboptimal PA scheme is developed to further reduce the complexity,where the characteristic of massive MIMO(i.e.,numerous receive antennas)is utilized for convex reformulation,and the rate constraint is converted to linear constraints.This suboptimal scheme only needs single-layer iteration,thus has lower complexity than the near-optimal scheme.Finally,we joint design the pilot power and data power to further improve the performance,and propose an two-stage algorithm to obtain joint PA.Simulation results verify the effectiveness of the proposed schemes,and superior SE performance is achieved.
基金supported in part by the National Natural Science Foundation of China(61933007, U21A2019, 62273005, 62273088, 62303301)the Program of Shanghai Academic/Technology Research Leader of China (20XD1420100)+2 种基金the Hainan Province Science and Technology Special Fund of China(ZDYF2022SHFZ105)the Natural Science Foundation of Anhui Province of China (2108085MA07)the Alexander von Humboldt Foundation of Germany。
文摘This paper investigates the anomaly-resistant decentralized state estimation(SE) problem for a class of wide-area power systems which are divided into several non-overlapping areas connected through transmission lines. Two classes of measurements(i.e., local measurements and edge measurements) are obtained, respectively, from the individual area and the transmission lines. A decentralized state estimator, whose performance is resistant against measurement with anomalies, is designed based on the minimum error entropy with fiducial points(MEEF) criterion. Specifically, 1) An augmented model, which incorporates the local prediction and local measurement, is developed by resorting to the unscented transformation approach and the statistical linearization approach;2) Using the augmented model, an MEEF-based cost function is designed that reflects the local prediction errors of the state and the measurement;and 3) The local estimate is first obtained by minimizing the MEEF-based cost function through a fixed-point iteration and then updated by using the edge measuring information. Finally, simulation experiments with three scenarios are carried out on the IEEE 14-bus system to illustrate the validity of the proposed anomaly-resistant decentralized SE scheme.
基金supported by National Natural Science Foundation of China(61403013)the Aero-Science Foundation of China(2015ZA51009)
文摘In this paper, an output-feedback tracking controller is proposed for a class of nonlinear non-minimum phase systems.To keep the unstable internal dynamics bounded, the method of output redefinition is applied to let the stability of the internal dynamics depend on that of redefined output, thus we only need to consider the new external dynamics rather than internal dynamics in the process of designing control law. To overcome the explosion of complexity problem in traditional backstepping design, the dynamic surface control(DSC) method is firstly used to deal with the problem of tracking control for the nonlinear non-minimum phase systems. The proposed outputfeedback DSC controller not only forces the system output to asymptotically track the desired trajectory, but also drives the unstable internal dynamics to follow its corresponding bounded and causal ideal internal dynamics, which is solved via stable system center method. Simulation results illustrate the validity of the proposed output-feedback DSC controller.
文摘This paper uses SWOT analysis, feasibility analysis of integration of urban and rural residents in China, including the overall analysis of the urban and rural integration China internal conditions, mainly for its overall advantages and disadvantages are analyzed; and the external environment, the system is mainly to raise the opportunities and threats were analyzed; in these. The external conditions are analyzed based on the construction of SWOT strategic matrix, found the advantages and disadvantages of the reform process of the integration of urban and rural subsistence allowances system in coexist, opportunities outweigh the challenges, so China＇s overall urban and rural integration construction is feasible.
文摘Active disturbance rejection control （ADRC）, as proposed by Prof. Jingqing Han, reduces first the plant dynamics to its canonical form, normally in the form of cascade integrators, for which the standard controller can be employed to meet the design specifications. This paper concerns with the selection of the canonical form for non-minimum phase systems. In particular, it is shown that, by employing the well known controllable canonical form, the uncertainties of such systems can be divided into two terms in the state space model, one in the control channel and the other in the output channel. The necessary and sufficient condition is obtained for the stability of the closed-loop system with the proposed canonical form and ADRC. Also, by showing the necessity of the detectability of the extended system as well as certain information of the system-s ＂zeros＂, we present the fundamental guidelines of design ADRC for non-minimum phase uncertain systems.
基金the National Natural Science Foundation of China(62176263,62103434,62003363)the Science Foundation for Distinguished Youth of Shaanxi Province(2021JC-35)+2 种基金the Youth Talent Promotion Program of Shaanxi Provincial Association for Science and Technology(20220123)the Natural Science Basic Research Program of Shaanxi Province(2022KJXX-99)the National Defense Basic Research Program of Technology and Industry for National Defense(JCKY2021912B001).
文摘This paper concerns minimum-energy leader-following formation design and analysis problems of distributed multiagent systems(DMASs)subjected to randomly switching topologies and aperiodic communication pauses.The critical feature of this paper is that the energy consumption during the formation control process is restricted by the minimum-energy constraint in the sense of the linear matrix inequality.Firstly,the leader-following formation control protocol is proposed based on the relative state information of neighboring agents,where the total energy consumption is considered.Then,minimum-energy leader-following formation design and analysis criteria are presented in the form of the linear matrix inequality,which can be checked by the generalized eigenvalue method.Especially,the value of the minimum-energy constraint is determined.An illustrative simulation is provided to show the effectiveness of the main results.
文摘Based on the conclusion of the related researches on China's rural poverty alleviation policies and poverty problems,studies of Chinese scholars on the convergence between rural minimum subsistence system and the development policies of poverty alleviation are illustrated and personal understandings proposed.On the one hand,considering the actual situations of the quickening of China's urbanization and deepening of poverty,it is necessary to make significant adjustment and transformation in China's poverty reduction policies and minimum subsistence security system.On the other hand,it is pointed out that there is no omnipotent experience to follow in the convergence of minimum subsistence security system and poverty reduction policies.The actual conditions in various regions should be taken into consideration.And it is suggested that China should achieve the organic integration of rural minimum subsistence security system and poverty alleviation policies from management,capital and policy.
基金support by the Center of Excellency Program of the Korea Science and Engineering Foundation (KOSEF)and Ministry of Science and Technology (MOST)(No.R11-2000-086-0000-0)through the Center for Advanced Plasma Surface Technology (CAPST)at the Sungkyunkwan University
文摘In this study, numerical analysis is performed to adopt the equivalence ratio on the high velocity oxygen fuel （HVOF） thermal spray coating systems equipped with a minimum length nozzle. The analysis is applied to investigate the axisymmetric, steady-state, turbulent, and chemically combusting flow both within the torch and in a free jet region between the torch and the substrate to be coated. The combustion is modeled using a single-step and eddy-dissipation model which assumes that the reaction rate is limited by the turbulent mixing rate of the fuel and oxidant. As the diameter of the nozzle throat is increased, the location of the Mach shock disc moves backward from the nozzle exit. As the throat diameter and the divergent portion are 6 mm and 8 mm, respectively, the pressure in the HVOF system is the lowest at the chamber and the expanding gas is steadily maintained with both high velocity and high temperature for different equivalence ratios. Thus, relatively minor amendments of the equivalence ratio and the geometry of HVOF can lead to improved control over coating characteristics.
基金supported in part by the National Natural Science Foundation of China(51939001,61976033,62273072)the Natural Science Foundation of Sichuan Province (2022NSFSC0903)。
文摘This paper investigates the consensus control of multi-agent systems(MASs) with constrained input using the dynamic event-triggered mechanism(ETM).Consider the MASs with small-scale networks where a centralized dynamic ETM with global information of the MASs is first designed.Then,a distributed dynamic ETM which only uses local information is developed for the MASs with large-scale networks.It is shown that the semi-global consensus of the MASs can be achieved by the designed bounded control protocol where the Zeno phenomenon is eliminated by a designable minimum inter-event time.In addition,it is easier to find a trade-off between the convergence rate and the minimum inter-event time by an adjustable parameter.Furthermore,the results are extended to regional consensus of the MASs with the bounded control protocol.Numerical simulations show the effectiveness of the proposed approach.
文摘New method for determination of optimal placement and value of installed capacity of renewable source of energy (RES) by the criterion of minimum losses of active power, that allows taking into consideration the dependence of RES on natural conditions of region, schedule of energy supply, parameters and configuration of distribution network is suggested in the paper. Results of computations of test scheme confirm the efficiency of the proposed method and its simplicity as compared with the methods considered in literature sources.
基金The financial supports from the Scientific research start-up funding of Zhoukou Normal University (ZKNUC2016022)National Natural Science Foundation of China (21536003, 21706057, and 21606078)the Natural Science Foundation of Guangxi Province (2016GXNSFAA380190) are gratefully acknowledged
文摘An accurate and reliable estimation of minimum miscibility pressure(MMP) of CO2-oil system is a critical task for the design and implementation of CO2 miscible displacement process.In this study,an improved CO2-oil MMP correlation was developed to predict the MMP values for both pure and impure CO2 injection cases based on ten influential factors,i.e.reservoir temperature(TR),molecular weight of C7+oil components(MWC7+),mole fraction of volatile oil components(xvol),mole fraction of C2-C4 oil components(xC2-C4),mole fraction of C5-C6 oil components(xCs-5-C6),and the gas stream mole fractions of CO2(yCO2),H2S(yH2S),C1(yC1),hydrocarbons(yHC)and N2(yN2).The accuracy of the improved correlation was evaluated against experimental data reported in literature concurrently with those estimated by several renowned correlations.It was found that the improved correlation provided higher prediction accuracy and consistency with literature experimental data than other literature correlations.In addition,the predictive capability of the improved correlation was further validated by predicting an experimentally measured CO2-Oil MMP data,and it showed an accurate result with the absolute deviation of 4.15%.Besides,the differential analysis of the improved correlation was analyzed to estimate the impact of parameters uncertainty in the original MMP data on the calculated results.Also,sensitivity analysis was performed to analyze the influence of each parameter on MMP qualitatively and quantitatively.The results revealed that the increase of xC2-C4,xC5-C6 and yH2 S lead to the decrease of MMP,while the increase of TR,MWC7+,xvol,yCO2,YC1,yHC and yN2 tend to increase the MMP.Overall,the relevance of each parameter with MMP follows the order of TR> xC5-C6> MWC7+> xvol> yH2 S> yHC> yCO2>yC1>yN2>xC2-C4.
文摘The surplus rural labors transferring to the city is an inevitable trend in the economic development of the reform and opening up. The household register system has made urban migrant workers free from the social security system and drift on the brink of city. Social assistance system concerning their interests is few. This article starts with the current situation of rural migrant workers in social assistance system, states the necessity and feasibility for bringing the migrant workers into the urban minimum living security system and according to the characteristics of the migrant workers on the reasonable classification, finally talks about existing obstacles and countermeasures of the migrant workers joining into the urban low income system. I believe that with the continuous reform of the registered permanent household register system, the continuous development of urbanization, the basic life of migrant worker will be guaranteed.
