Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback ...Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.展开更多
Small and medium-sized enterprises(SMEs)constitute the primary drivers of production within the nation’s existing enterprise landscape.They represent the most dynamic segment of the national economy and play a pivota...Small and medium-sized enterprises(SMEs)constitute the primary drivers of production within the nation’s existing enterprise landscape.They represent the most dynamic segment of the national economy and play a pivotal role in supporting economic growth,fostering employment,and enhancing people’s livelihoods.However,despite their significant and extensive organizational structures,only a fraction of these companies have established internal control systems,and even fewer possess robust ones.Building upon this premise and considering the prevailing circumstances of SMEs,this paper undertakes an empirical analysis of monetary fund management within this sector.It delves into the operational intricacies,exploring how monetary funds should be effectively implemented to ensure their safety and integrity.Furthermore,it proposes viable strategies to enhance the circulation efficiency of monetary funds,thereby maximizing benefits for enterprises.Addressing these challenges is crucial for SME managers striving to achieve sustainable profit growth and navigate the complexities of financial management.展开更多
As an important pillar of national economic development,state-owned enterprises,their operational efficiency,and risk management ability are directly related to the stability and security of the national economy.As an...As an important pillar of national economic development,state-owned enterprises,their operational efficiency,and risk management ability are directly related to the stability and security of the national economy.As an important part of enterprise management,internal control management plays an irreplaceable role.Especially in the current domestic and international economic situation is complex and changeable,market competition is increasingly fierce environment,to strengthen the internal control management of state-owned enterprises and risk prevention measures is particularly important.This paper starts with the importance of internal control management and risk prevention for state-owned enterprises,and analyzes the problems and strategies in the internal control management and risk prevention of state-owned enterprises,in order to build a more comprehensive and efficient risk management system for state-owned enterprises to adapt to the ever-changing market environment and realize sustainable development.展开更多
Fixed assets in universities occupy an important position in university management due to their wide coverage and large amount of money.Due to insufficient funding supply,private universities mainly focus on the alloc...Fixed assets in universities occupy an important position in university management due to their wide coverage and large amount of money.Due to insufficient funding supply,private universities mainly focus on the allocation and utilization of fixed assets,which reflects the overall characteristics of cautious allocation,maximum utilization,and delayed elimination in the actual management of fixed assets.This article aims to conduct research and analysis on the entire lifecycle process of the allocation,use,and disposal of fixed assets in private universities,summarize the problems existing in the internal control of fixed assets in private universities,and propose corresponding countermeasures and suggestions in a targeted manner.展开更多
This paper outlines the internal control management of hospital accounting and finance,introducing its concept,importance,and objectives.It then analyzes the problems existing in the internal control management of hos...This paper outlines the internal control management of hospital accounting and finance,introducing its concept,importance,and objectives.It then analyzes the problems existing in the internal control management of hospital accounting and finance,including an unsound management system,insufficient system implementation,inadequate risk assessment and control capabilities,poor information communication,weak internal supervision,and uneven personnel quality.The reasons for these problems are also analyzed,including outdated management concepts,irrational organizational structures,imperfect training and incentive mechanisms,low levels of information technology,and changes in the external environment.This paper proposes improvement measures for the internal control management of hospital accounting,including enhancing the management system,strengthening system implementation,improving risk assessment and control capabilities,enhancing the information communication mechanism,strengthening internal supervision,improving personnel quality,advancing information technology,and adapting to changes in the external environment.展开更多
Internal solitary wave(ISW),as a typical marine dynamic process in the deep sea,widely exists in oceans and marginal seas worldwide.The interaction between ISW and the seafloor mainly occurs in the bottom boundary lay...Internal solitary wave(ISW),as a typical marine dynamic process in the deep sea,widely exists in oceans and marginal seas worldwide.The interaction between ISW and the seafloor mainly occurs in the bottom boundary layer.For the seabed boundary layer of the deep sea,ISW is the most important dynamic process.This study analyzed the current status,hotspots,and frontiers of research on the interaction between ISW and the seafloor by CiteSpace.Focusing on the action of ISW on the seabed,such as transformation and reaction,a large amount of research work and results were systematically analyzed and summarized.On this basis,this study analyzed the wave–wave interaction and interaction between ISW and the bedform or slope of the seabed,which provided a new perspective for an in‐depth understanding of the interaction between ISW and the seafloor.Finally,the latest research results of the bottom boundary layer and marine engineering stability by ISW were introduced,and the unresolved problems in the current research work were summarized.This study provides a valuable reference for further research on the hazards of ISW to marine engineering geology.展开更多
Focusing on the two themes of"internal control"and"risk management",this paper makes an in-depth analysis of the current situation of risk management and internal control of Moutai Group.It analyze...Focusing on the two themes of"internal control"and"risk management",this paper makes an in-depth analysis of the current situation of risk management and internal control of Moutai Group.It analyzes the current situation of risk management and internal control of Moutai Group.It is found that the risk management of Moutai Group is not perfect,the information exchange is not smooth,and the internal control assessment is not perfect.Finally,it puts forward some corresponding countermeasures,including establishing an effective information communication mechanism,perfecting the risk assessment system,and strengthening the construction of the professional talent team.展开更多
Strategic management oriented enterprise internal control is an inevitable choice after the enterprise develops to a certain scale,and it is also an important starting point for enterprises to adjust their own strateg...Strategic management oriented enterprise internal control is an inevitable choice after the enterprise develops to a certain scale,and it is also an important starting point for enterprises to adjust their own strategic layout and resource allocation.With the continuous expansion of the scope of internal control supervision,the traditional mode of internal control supervision has become more and more restricted.In view of this,the present study started from the necessity of internal control supervision from the overall and top-level perspectives,and analyzed the current problems in the internal control of enterprises from the perspective of strategic management.The problems include the lack of methods and tools of strategic management,insufficient awareness of strategic risk management,insufficient expansion of internal control objects,insufficient prior intervention in internal control supervision,etc.Finally,it came up with the idea of constructing strategic enterprise internal control,in order to provide an effective reference for the study of enterprise internal control.展开更多
A modified two-degrees-of-freedom( M-TDOF) internal model control( IMC) method is proposed for non-square systems with multiple time delays and right-half-plane( RHP) zeros. In this method,pseudo-inverse is introduced...A modified two-degrees-of-freedom( M-TDOF) internal model control( IMC) method is proposed for non-square systems with multiple time delays and right-half-plane( RHP) zeros. In this method,pseudo-inverse is introduced to design the internal model controller,and a desired closed-loop transfer function is designed to eliminate the unrealizable factors of the derived controller. In addition,set-point tracking and load-disturbance rejection of each process are separately controlled by two controllers. The simulation results show that in addition to high decoupling performance and robustness,the proposed control method also effectively improves loaddisturbance rejection and simultaneously optimizes the input tracking performance and disturbance rejection performance by selecting the parameters of controllers. Furthermore,the higher tolerance of model mismatch is achieved in this paper.展开更多
Pyropia haitanensis is an economically important mariculture crop in China and has a high research value for several life phenomena, for example environmental tolerance. To explore the mechanisms underlying these char...Pyropia haitanensis is an economically important mariculture crop in China and has a high research value for several life phenomena, for example environmental tolerance. To explore the mechanisms underlying these characteristics, gene expression has been investigated at the whole transcriptome level. Gene expression studies using quantitative real-time PCR should start by selecting an appropriate internal control gene; therefore, the absolute expression abundance of six housekeeping genes （18S rRNA （18S）, ubiquitin-conju-ating enzyme （UBC）, actin （ACT）, β-tubulin （TUB）, elongation factors 2 （EF2）, and glyceraldehyde-3-phos- phate dehydrogenase （GAPDH） examined by the quantitative real-time PCR in samples corresponding to different strains, life-cycle stages and abiotic stress treatments. Their expression stabilities were assessed by the comparative cycle threshold （Ct） method and by two different software packages： geNorm and NormFinder. The most stable housekeeping gene is UBC and the least stable housekeeping is GADPH. Thus, it is proposed that the most appropriate internal control gene for expression analyses in P. haitanensis is UBC. The results pave the way for further gene expression analyses of different aspects of P. haitanensis biology including different strains, life-history stages and abiotic stress responses.展开更多
A novel control scheme of active disturbance rejection internal model control(ADRIMC) is proposed to improve the anti-interference ability and robustness for the dead-time process. The active anti-interference concept...A novel control scheme of active disturbance rejection internal model control(ADRIMC) is proposed to improve the anti-interference ability and robustness for the dead-time process. The active anti-interference concept is introduced into the internal model control(IMC) by analyzing the relationship between IMC and disturbance observer control(DOB). Further, a design process of disturbance filter is presented to realize the active anti-interference ability for ADRIMC scheme. The disturbance filter is used to estimate an equivalent disturbance consisting of both external disturbances and internal disturbances caused by model mismatches.Simulation results demonstrate that the proposed method possesses a good disturbance rejection performance, though losing some partial dynamic performance. In other words, the proposed method shows a tradeoff between the dynamic performance and the system robust.展开更多
In this paper,a multi-loop internal model control(IMC) scheme in conjunction with feed-forward strategy based on the dynamic partial least squares(DyPLS) framework is proposed.Unlike the traditional methods to decoupl...In this paper,a multi-loop internal model control(IMC) scheme in conjunction with feed-forward strategy based on the dynamic partial least squares(DyPLS) framework is proposed.Unlike the traditional methods to decouple multi-input multi-output(MIMO) systems,the DyPLS framework automatically decomposes the MIMO process into a multi-loop system in the PLS subspace in the modeling stage.The dynamic filters with identical structure are used to build the dynamic PLS model,which retains the orthogonality among the latent variables.To address the model mismatch problem,an off-line least squares method is applied to obtain a set of optimal filter parameters in each latent space.Without losing the merits of model-based control,a simple and easy-tuned IMC structure is readily carried over to the dynamic PLS control framework.In addition,by projecting the measurable disturbance into the latent subspace,a multi-loop feed-forward control is yielded to achieve better performance for disturbance rejection.Simulation results of a distillation column are used to further demonstrate this new strategy outperforms conventional control schemes in servo behavior and disturbance rejection.展开更多
Because of vehicle＇s external disturbances and model uncertainties,robust control algorithms have obtained popularity in vehicle stability control.The robust control usually gives up performance in order to guarantee...Because of vehicle＇s external disturbances and model uncertainties,robust control algorithms have obtained popularity in vehicle stability control.The robust control usually gives up performance in order to guarantee the robustness of the control algorithm,therefore an improved robust internal model control（IMC） algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness.The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties.In order to separate the design process of model tracking from the robustness design process,the improved 2 degree of freedom（DOF） robust internal model controller structure is given from the standard Youla parameterization.Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm,on the basis of a nonlinear vehicle simulation model with a magic tyre model.Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance,which can enhance the vehicle stability and handling,regardless of variations of the vehicle model parameters and the external crosswind interferences.Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained.展开更多
By means of the existence and uniqueness of semi-global C1 solution to the mixed initial-boundary value problem with general nonlinear boundary conditions for first order quasilinear hyperbolic systems with zero eigen...By means of the existence and uniqueness of semi-global C1 solution to the mixed initial-boundary value problem with general nonlinear boundary conditions for first order quasilinear hyperbolic systems with zero eigenvalues,the local exact boundary controllability for higher order quasilinear hyperbolic equations is established.展开更多
Spatial control of lithium deposition is the most important issue in lithium-metal batteries because of the considerable control of lithium dendrite suppression via the uniform distribution of Li^(+)flux.Although seed...Spatial control of lithium deposition is the most important issue in lithium-metal batteries because of the considerable control of lithium dendrite suppression via the uniform distribution of Li^(+)flux.Although seed materials are crucial for the behavior of lithium deposition,in-depth studies on their physical and chemical control have not been conducted.Here,we describe a new design of seed structure comprising a wrinkled Cu/graphene substrate surrounded by copper(Ⅰ)oxide(Cu_(2)O)on a graphene grain boundary over a large area,which is fabricated by the oxidation of the Cu surface via graphene boundary defects by using chemical vapor deposition(CVD).Scanning and transmission electron microscopy results reveal that Cu_(2)O on the graphene boundary can render a preferential reaction with lithium during the first deposition and assist in the uniform deposition of lithium by preventing the agglomeration of lithium clusters during the second deposition.This two-step process is attributed to the degree of selectivity due to the difference in lithium affinity,which allows long-term electrochemical stability and a high rate capability via boundary effects.This study highlights the significance of the boundary effect,which can open new avenues for the formation of a large family of seed structures in lithium-metal batteries.展开更多
In this paper, the nonreflecting boundary conditions based upon fundamental ideas of the linear analysis are developed for gas dynamic equations, and the modified boundary conditions for Navier-Stokes equations are pr...In this paper, the nonreflecting boundary conditions based upon fundamental ideas of the linear analysis are developed for gas dynamic equations, and the modified boundary conditions for Navier-Stokes equations are proposed as a substitute of the nonreflecting boundary conditions inside boundary layers near rigid walls. These derived boundary conditions are then applied to calculations both for the Euler equations and the Navier-Stokes equations to determine if they can produce acceptable results for the subsonic flows in channels. The numerical results obtained by an implicit second-order upwind difference scheme show the effective- ness and generality of the boundary conditions. Furthermore, the formulae and the analysis performed here may be extended to three dimensional problems.展开更多
Because of the tire nonlinearity and vehicle＇s parameters＇uncertainties,robust control methods based on the worst cases,such as H_∞,μsynthesis,have been widely used in active front steering control,however,in orde...Because of the tire nonlinearity and vehicle＇s parameters＇uncertainties,robust control methods based on the worst cases,such as H_∞,μsynthesis,have been widely used in active front steering control,however,in order to guarantee the stability of active front steering system（AFS）controller,the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS control.In this paper,a generalized internal model robust control（GIMC）that can overcome the contradiction between performance and stability is used in the AFS control.In GIMC,the Youla parameterization is used in an improved way.And GIMC controller includes two sections：a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters＇uncertainties and some external disturbances.Simulations of double lane change（DLC）maneuver and that of braking on split-μroad are conducted to compare the performance and stability of the GIMC control,the nominal performance PID controller and the H_∞controller.Simulation results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle＇s parameters variations,H_∞controller is conservative so that the performance is a little low,and only the GIMC controller overcomes the contradiction between performance and robustness,which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS controller.Therefore,the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system,that is,can solve the instability of PID or LQP control methods and the low performance of the standard H_∞controller.展开更多
The flat-plate turbulent boundary layer at Reτ=1140 is manipulated using a spanwise array of bidirectional dielectric barrier discharge(DBD)plasma actuators.Based on the features of no moving mechanical parts in the ...The flat-plate turbulent boundary layer at Reτ=1140 is manipulated using a spanwise array of bidirectional dielectric barrier discharge(DBD)plasma actuators.Based on the features of no moving mechanical parts in the DBD plasma control technology and hot-wire anemometer velocity measurements,a novel convenient method of local drag reduction(DR)measurement is proposed by measuring the single-point velocity within the linear region of the viscous sublayer.We analyze the premise of using the method,and the maximum effective measurement range of-73.1%<DR<42.2%is obtained according to the experimental environment in this work.The local drag decreases downstream of the center of two adjacent upper electrodes and increases downstream of the upper electrodes.The magnitude of the local DR increases with increasing voltage and decreases as it moves away from the actuators.For the spanwise position in between,the streamwise distribution of the local DR is very dependent on the voltage.The variable-interval time-average detection results reveal that all bursting intensities are reduced compared to the baseline,and the amount of reduction is comparable to the absolute values of the local DR.Compared with previous results,we infer that the control mechanism is that many meandering streaks are combined together into single stabilized streaks.展开更多
An adaptive internal mode control is proposed to eliminate effectively periodic disturbance with uncertain frequency caused by input error angle of PIGA （Pendulous Integrating Gyro Accelerometer）. An adaptive algori...An adaptive internal mode control is proposed to eliminate effectively periodic disturbance with uncertain frequency caused by input error angle of PIGA （Pendulous Integrating Gyro Accelerometer）. An adaptive algorithm with periodic disturbance frequency identification on line is applied and the internal model controller parameters are adjusted to eliminate disturbance. Then the convergence of this algorithm and the stability of the system are proved by the averaging method. Simulation results verify the proposed scheme can eliminate periodic disturbance and improve the test precision for PIGA effectively.展开更多
This paper proposes a design of internal model control systems for process with delay by using support vector regression(SVR).The proposed system fully uses the excellent nonlinear estimation performance of SVR with t...This paper proposes a design of internal model control systems for process with delay by using support vector regression(SVR).The proposed system fully uses the excellent nonlinear estimation performance of SVR with the structural risk minimization principle.Closed-system stability and steady error are analyzed for the existence of modeling errors.The simulations show that the proposed control systems have the better control performance than that by neural networks in the cases of the training samples with small size and noises.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.62275272)the Training Program for Excellent Young Innovators of Changsha(Grant No.KQ2305025)。
文摘Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.
文摘Small and medium-sized enterprises(SMEs)constitute the primary drivers of production within the nation’s existing enterprise landscape.They represent the most dynamic segment of the national economy and play a pivotal role in supporting economic growth,fostering employment,and enhancing people’s livelihoods.However,despite their significant and extensive organizational structures,only a fraction of these companies have established internal control systems,and even fewer possess robust ones.Building upon this premise and considering the prevailing circumstances of SMEs,this paper undertakes an empirical analysis of monetary fund management within this sector.It delves into the operational intricacies,exploring how monetary funds should be effectively implemented to ensure their safety and integrity.Furthermore,it proposes viable strategies to enhance the circulation efficiency of monetary funds,thereby maximizing benefits for enterprises.Addressing these challenges is crucial for SME managers striving to achieve sustainable profit growth and navigate the complexities of financial management.
文摘As an important pillar of national economic development,state-owned enterprises,their operational efficiency,and risk management ability are directly related to the stability and security of the national economy.As an important part of enterprise management,internal control management plays an irreplaceable role.Especially in the current domestic and international economic situation is complex and changeable,market competition is increasingly fierce environment,to strengthen the internal control management of state-owned enterprises and risk prevention measures is particularly important.This paper starts with the importance of internal control management and risk prevention for state-owned enterprises,and analyzes the problems and strategies in the internal control management and risk prevention of state-owned enterprises,in order to build a more comprehensive and efficient risk management system for state-owned enterprises to adapt to the ever-changing market environment and realize sustainable development.
文摘Fixed assets in universities occupy an important position in university management due to their wide coverage and large amount of money.Due to insufficient funding supply,private universities mainly focus on the allocation and utilization of fixed assets,which reflects the overall characteristics of cautious allocation,maximum utilization,and delayed elimination in the actual management of fixed assets.This article aims to conduct research and analysis on the entire lifecycle process of the allocation,use,and disposal of fixed assets in private universities,summarize the problems existing in the internal control of fixed assets in private universities,and propose corresponding countermeasures and suggestions in a targeted manner.
文摘This paper outlines the internal control management of hospital accounting and finance,introducing its concept,importance,and objectives.It then analyzes the problems existing in the internal control management of hospital accounting and finance,including an unsound management system,insufficient system implementation,inadequate risk assessment and control capabilities,poor information communication,weak internal supervision,and uneven personnel quality.The reasons for these problems are also analyzed,including outdated management concepts,irrational organizational structures,imperfect training and incentive mechanisms,low levels of information technology,and changes in the external environment.This paper proposes improvement measures for the internal control management of hospital accounting,including enhancing the management system,strengthening system implementation,improving risk assessment and control capabilities,enhancing the information communication mechanism,strengthening internal supervision,improving personnel quality,advancing information technology,and adapting to changes in the external environment.
基金National Natural Science Foundation of China,Grant/Award Number:42107158Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20210527。
文摘Internal solitary wave(ISW),as a typical marine dynamic process in the deep sea,widely exists in oceans and marginal seas worldwide.The interaction between ISW and the seafloor mainly occurs in the bottom boundary layer.For the seabed boundary layer of the deep sea,ISW is the most important dynamic process.This study analyzed the current status,hotspots,and frontiers of research on the interaction between ISW and the seafloor by CiteSpace.Focusing on the action of ISW on the seabed,such as transformation and reaction,a large amount of research work and results were systematically analyzed and summarized.On this basis,this study analyzed the wave–wave interaction and interaction between ISW and the bedform or slope of the seabed,which provided a new perspective for an in‐depth understanding of the interaction between ISW and the seafloor.Finally,the latest research results of the bottom boundary layer and marine engineering stability by ISW were introduced,and the unresolved problems in the current research work were summarized.This study provides a valuable reference for further research on the hazards of ISW to marine engineering geology.
文摘Focusing on the two themes of"internal control"and"risk management",this paper makes an in-depth analysis of the current situation of risk management and internal control of Moutai Group.It analyzes the current situation of risk management and internal control of Moutai Group.It is found that the risk management of Moutai Group is not perfect,the information exchange is not smooth,and the internal control assessment is not perfect.Finally,it puts forward some corresponding countermeasures,including establishing an effective information communication mechanism,perfecting the risk assessment system,and strengthening the construction of the professional talent team.
文摘Strategic management oriented enterprise internal control is an inevitable choice after the enterprise develops to a certain scale,and it is also an important starting point for enterprises to adjust their own strategic layout and resource allocation.With the continuous expansion of the scope of internal control supervision,the traditional mode of internal control supervision has become more and more restricted.In view of this,the present study started from the necessity of internal control supervision from the overall and top-level perspectives,and analyzed the current problems in the internal control of enterprises from the perspective of strategic management.The problems include the lack of methods and tools of strategic management,insufficient awareness of strategic risk management,insufficient expansion of internal control objects,insufficient prior intervention in internal control supervision,etc.Finally,it came up with the idea of constructing strategic enterprise internal control,in order to provide an effective reference for the study of enterprise internal control.
基金Sponsored by the Fundamental Research Funds for the Central Universities(Grant No.N110304008)the National Natural Science Foundation of China(Grant No.61374137)
文摘A modified two-degrees-of-freedom( M-TDOF) internal model control( IMC) method is proposed for non-square systems with multiple time delays and right-half-plane( RHP) zeros. In this method,pseudo-inverse is introduced to design the internal model controller,and a desired closed-loop transfer function is designed to eliminate the unrealizable factors of the derived controller. In addition,set-point tracking and load-disturbance rejection of each process are separately controlled by two controllers. The simulation results show that in addition to high decoupling performance and robustness,the proposed control method also effectively improves loaddisturbance rejection and simultaneously optimizes the input tracking performance and disturbance rejection performance by selecting the parameters of controllers. Furthermore,the higher tolerance of model mismatch is achieved in this paper.
基金The National High Technology Research&Development Program of China under contract No.2012AA10A411the National Natural Science Foundation of China under contract Nos 41176151 and 41276177
文摘Pyropia haitanensis is an economically important mariculture crop in China and has a high research value for several life phenomena, for example environmental tolerance. To explore the mechanisms underlying these characteristics, gene expression has been investigated at the whole transcriptome level. Gene expression studies using quantitative real-time PCR should start by selecting an appropriate internal control gene; therefore, the absolute expression abundance of six housekeeping genes （18S rRNA （18S）, ubiquitin-conju-ating enzyme （UBC）, actin （ACT）, β-tubulin （TUB）, elongation factors 2 （EF2）, and glyceraldehyde-3-phos- phate dehydrogenase （GAPDH） examined by the quantitative real-time PCR in samples corresponding to different strains, life-cycle stages and abiotic stress treatments. Their expression stabilities were assessed by the comparative cycle threshold （Ct） method and by two different software packages： geNorm and NormFinder. The most stable housekeeping gene is UBC and the least stable housekeeping is GADPH. Thus, it is proposed that the most appropriate internal control gene for expression analyses in P. haitanensis is UBC. The results pave the way for further gene expression analyses of different aspects of P. haitanensis biology including different strains, life-history stages and abiotic stress responses.
基金Project(61273132)supported by the National Natural Foundation of ChinaProject(20110010010)supported by Higher School Specialized Research Fund for the Doctoral Program,China
文摘A novel control scheme of active disturbance rejection internal model control(ADRIMC) is proposed to improve the anti-interference ability and robustness for the dead-time process. The active anti-interference concept is introduced into the internal model control(IMC) by analyzing the relationship between IMC and disturbance observer control(DOB). Further, a design process of disturbance filter is presented to realize the active anti-interference ability for ADRIMC scheme. The disturbance filter is used to estimate an equivalent disturbance consisting of both external disturbances and internal disturbances caused by model mismatches.Simulation results demonstrate that the proposed method possesses a good disturbance rejection performance, though losing some partial dynamic performance. In other words, the proposed method shows a tradeoff between the dynamic performance and the system robust.
基金Supported by the National Natural Science Foundation of China（60574047） the National High Technology Research and Development Program of China（2007AA04Z168 2009AA04Z154） the Research Fund for the Doctoral Program of Higher Education in China（20050335018）
文摘In this paper,a multi-loop internal model control(IMC) scheme in conjunction with feed-forward strategy based on the dynamic partial least squares(DyPLS) framework is proposed.Unlike the traditional methods to decouple multi-input multi-output(MIMO) systems,the DyPLS framework automatically decomposes the MIMO process into a multi-loop system in the PLS subspace in the modeling stage.The dynamic filters with identical structure are used to build the dynamic PLS model,which retains the orthogonality among the latent variables.To address the model mismatch problem,an off-line least squares method is applied to obtain a set of optimal filter parameters in each latent space.Without losing the merits of model-based control,a simple and easy-tuned IMC structure is readily carried over to the dynamic PLS control framework.In addition,by projecting the measurable disturbance into the latent subspace,a multi-loop feed-forward control is yielded to achieve better performance for disturbance rejection.Simulation results of a distillation column are used to further demonstrate this new strategy outperforms conventional control schemes in servo behavior and disturbance rejection.
基金Supported by National Natural Science Foundation of China(Grant No.51375009)PhD Research Foundation of Liaocheng University,China(Grant No.318051523)Tsinghua University Initiative Scientific Research Program,China
文摘Because of vehicle＇s external disturbances and model uncertainties,robust control algorithms have obtained popularity in vehicle stability control.The robust control usually gives up performance in order to guarantee the robustness of the control algorithm,therefore an improved robust internal model control（IMC） algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness.The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties.In order to separate the design process of model tracking from the robustness design process,the improved 2 degree of freedom（DOF） robust internal model controller structure is given from the standard Youla parameterization.Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm,on the basis of a nonlinear vehicle simulation model with a magic tyre model.Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance,which can enhance the vehicle stability and handling,regardless of variations of the vehicle model parameters and the external crosswind interferences.Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained.
文摘By means of the existence and uniqueness of semi-global C1 solution to the mixed initial-boundary value problem with general nonlinear boundary conditions for first order quasilinear hyperbolic systems with zero eigenvalues,the local exact boundary controllability for higher order quasilinear hyperbolic equations is established.
基金funded by the Saudi Aramco-KAIST CO_(2)Management Centersupported by a grant from the National Research Foundation of Korea+1 种基金funded by the Ministry of Science,ICT,and Future Planning(Grant no.2021K1A4A8A01079356)supported by the National Research Foundation of Korea(NRF)fund(NRF-2020M3H4A3081874).
文摘Spatial control of lithium deposition is the most important issue in lithium-metal batteries because of the considerable control of lithium dendrite suppression via the uniform distribution of Li^(+)flux.Although seed materials are crucial for the behavior of lithium deposition,in-depth studies on their physical and chemical control have not been conducted.Here,we describe a new design of seed structure comprising a wrinkled Cu/graphene substrate surrounded by copper(Ⅰ)oxide(Cu_(2)O)on a graphene grain boundary over a large area,which is fabricated by the oxidation of the Cu surface via graphene boundary defects by using chemical vapor deposition(CVD).Scanning and transmission electron microscopy results reveal that Cu_(2)O on the graphene boundary can render a preferential reaction with lithium during the first deposition and assist in the uniform deposition of lithium by preventing the agglomeration of lithium clusters during the second deposition.This two-step process is attributed to the degree of selectivity due to the difference in lithium affinity,which allows long-term electrochemical stability and a high rate capability via boundary effects.This study highlights the significance of the boundary effect,which can open new avenues for the formation of a large family of seed structures in lithium-metal batteries.
文摘In this paper, the nonreflecting boundary conditions based upon fundamental ideas of the linear analysis are developed for gas dynamic equations, and the modified boundary conditions for Navier-Stokes equations are proposed as a substitute of the nonreflecting boundary conditions inside boundary layers near rigid walls. These derived boundary conditions are then applied to calculations both for the Euler equations and the Navier-Stokes equations to determine if they can produce acceptable results for the subsonic flows in channels. The numerical results obtained by an implicit second-order upwind difference scheme show the effective- ness and generality of the boundary conditions. Furthermore, the formulae and the analysis performed here may be extended to three dimensional problems.
基金Supported by National Natural Science Foundation of China(Grant Nos.11072106,51375009)
文摘Because of the tire nonlinearity and vehicle＇s parameters＇uncertainties,robust control methods based on the worst cases,such as H_∞,μsynthesis,have been widely used in active front steering control,however,in order to guarantee the stability of active front steering system（AFS）controller,the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS control.In this paper,a generalized internal model robust control（GIMC）that can overcome the contradiction between performance and stability is used in the AFS control.In GIMC,the Youla parameterization is used in an improved way.And GIMC controller includes two sections：a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters＇uncertainties and some external disturbances.Simulations of double lane change（DLC）maneuver and that of braking on split-μroad are conducted to compare the performance and stability of the GIMC control,the nominal performance PID controller and the H_∞controller.Simulation results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle＇s parameters variations,H_∞controller is conservative so that the performance is a little low,and only the GIMC controller overcomes the contradiction between performance and robustness,which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS controller.Therefore,the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system,that is,can solve the instability of PID or LQP control methods and the low performance of the standard H_∞controller.
基金the financial support received from the National Science Fund for Distinguished Young Scholars(No.12102359)。
文摘The flat-plate turbulent boundary layer at Reτ=1140 is manipulated using a spanwise array of bidirectional dielectric barrier discharge(DBD)plasma actuators.Based on the features of no moving mechanical parts in the DBD plasma control technology and hot-wire anemometer velocity measurements,a novel convenient method of local drag reduction(DR)measurement is proposed by measuring the single-point velocity within the linear region of the viscous sublayer.We analyze the premise of using the method,and the maximum effective measurement range of-73.1%<DR<42.2%is obtained according to the experimental environment in this work.The local drag decreases downstream of the center of two adjacent upper electrodes and increases downstream of the upper electrodes.The magnitude of the local DR increases with increasing voltage and decreases as it moves away from the actuators.For the spanwise position in between,the streamwise distribution of the local DR is very dependent on the voltage.The variable-interval time-average detection results reveal that all bursting intensities are reduced compared to the baseline,and the amount of reduction is comparable to the absolute values of the local DR.Compared with previous results,we infer that the control mechanism is that many meandering streaks are combined together into single stabilized streaks.
文摘An adaptive internal mode control is proposed to eliminate effectively periodic disturbance with uncertain frequency caused by input error angle of PIGA （Pendulous Integrating Gyro Accelerometer）. An adaptive algorithm with periodic disturbance frequency identification on line is applied and the internal model controller parameters are adjusted to eliminate disturbance. Then the convergence of this algorithm and the stability of the system are proved by the averaging method. Simulation results verify the proposed scheme can eliminate periodic disturbance and improve the test precision for PIGA effectively.
文摘This paper proposes a design of internal model control systems for process with delay by using support vector regression(SVR).The proposed system fully uses the excellent nonlinear estimation performance of SVR with the structural risk minimization principle.Closed-system stability and steady error are analyzed for the existence of modeling errors.The simulations show that the proposed control systems have the better control performance than that by neural networks in the cases of the training samples with small size and noises.
