The stabilization using a stable compensator does not introduce additional unstable zeros into the closed-loop transfer function beyond those of the original plant, so it is a desirable compensator, the price is that ...The stabilization using a stable compensator does not introduce additional unstable zeros into the closed-loop transfer function beyond those of the original plant, so it is a desirable compensator, the price is that the compensator’s order will go up. This note considered the order of stable compensators for a class of time-delay systems. First, it is shown that for single-loop plants with at most one real right-half plane zero, a special upper bound for the minimal order of a strongly stabilizing compensator can be obtained in terms of the plant order; Second, it is shown that approximate unstable pole-zero cancellation does not occur, and the distances between distinct unstable zeroes are bounded below by a positive constant, then it is possible to find an upper bound for the minimal order of a strongly stabilizing compensator.展开更多
Composite cathodes integrating Ni-rich layered oxides and oxide solid electrolytes are essential for highenergy all-solid-state lithium-ion batteries(ASSLBs),yet interfacial degradation during high-temperature co-sint...Composite cathodes integrating Ni-rich layered oxides and oxide solid electrolytes are essential for highenergy all-solid-state lithium-ion batteries(ASSLBs),yet interfacial degradation during high-temperature co-sintering(>600℃)remains a critical challenge.While surface passivation strategies mitigate reactions below 400℃,their effectiveness diminishes at elevated temperatures due to inability to counteract Li^(+)concentration gradients.Here,we introduce in situ lithium compensators,i.e.,LiOH/Li_(2)CO_(3),into NCM-LATP composite cathodes to dynamically replenish Li^(+)during co-sintering.These additives melt to form transient Li^(+)-rich phases that back-diffuse Li^(+)into NCM lattices,suppressing layered-to-rock salt transitions and stabilizing the interface.Quasi in situ XRD confirms retention of the layered structure at temperature up to 700℃,while electrochemical tests demonstrate a reversible capacity of 222.2 mA h g^(-1)—comparable to NCM before co-sintering—and an impressive 65.3% capacity retention improvement over100 cycles.In contrast,uncompensated cathodes exhibit severe degradation to 96.5 mA h g^(-1)due to Li depletion and resistive Li-Ti-O interphases.This strategy integrates sacrificial chemistry with scalable powder-mixing workflows,achieving a 93.4% reduction in interfacial impedance.By addressing Li^(+)flux homogenization and structural stability,this work provides a practical pathway toward industrialscale fabrication of high-performance ASSLBs.展开更多
The prediction and compensation control of marine ship motion is crucial for ensuring the safety of offshore wind turbine loading and unloading operations.However,the accuracy of prediction and control is significantl...The prediction and compensation control of marine ship motion is crucial for ensuring the safety of offshore wind turbine loading and unloading operations.However,the accuracy of prediction and control is significantly affected by the hysteresis phenomenon in the wave compensation system.To address this issue,a ship heave motion prediction is proposed in this paper on the basis of the Gauss-DeepAR(AR stands for autoregressive recurrent)model and the Hilbert−Huang time-delay compensation control strategy.Initially,the zero upward traveling wave period of the level 4−6 sea state ship heave motion is analyzed,which serves as the input sliding window for the Gauss-DeepAR prediction model,and probability predictions at different wave direction angles are conducted.Next,considering the hysteresis characteristics of the ship heave motion compensation platform,the Hilbert−Huang transform is employed to analyze and calculate the hysteresis delay of the compensation platform.After the optimal control action value is subsequently calculated,simulations and hardware platform tests are conducted.The simulation results demonstrated that the Gauss-DeepAR model outperforms autoregressive integrated moving average model(ARIMA),support vector machine(SVM),and longshort-term memory(LSTM)in predicting non-independent identically distributed datasets at a 90°wave direction angle in the level 4−6 sea states.Furthermore,the model has good predictive performance and generalizability for non-independent and non-uniformly distributed datasets at a 180°wave direction angle.The hardware platform compensation test results revealed that the Hilbert–Huang method has an outstanding effect on determining the hysteretic delay and selecting the optimal control action value,and the compensation efficiency was higher than 90%in the level 4−6 sea states.展开更多
Systems that are subject to both time-delay in state and input saturation are considered. We synthesize the anti-windup gain to enlarge the estimation of domain of attraction while guaranteeing the stability of the cl...Systems that are subject to both time-delay in state and input saturation are considered. We synthesize the anti-windup gain to enlarge the estimation of domain of attraction while guaranteeing the stability of the closed-loop system. An ellipsoid and a polyhedral set are used to bound the state of the system, which make a new sector condition valid. Other than an iterative algorithm, a direct designing algorithm is derived to compute the anti-windup compensator gain, which reduces the conservatism greatly. We analyze the delay-independent and delay-dependent cases, respectively. Finally, an optimization algorithm in the form of LMIs is constructed to compute the compensator gain which maximizes the estimation of domain of attraction. Numerical examples are presented to demonstrate the effectiveness of our approach.展开更多
Energy-regenerative suspension combined with piezoelectric and electromagnetic transduction has evolved into a core technological pathway in advancing automotive design paradigms.With the aim of improving energy harve...Energy-regenerative suspension combined with piezoelectric and electromagnetic transduction has evolved into a core technological pathway in advancing automotive design paradigms.With the aim of improving energy harvesting performance,time-delayed feedback control is widely used in an energy-regenerative suspension system under different external disturbances in this paper.Meanwhile,limited research has addressed the stochastic dynamics of time-delayed nonlinear energy-regenerative suspension systems.Different from previous studies,this work studies the stochastic response and P-bifurcation of the nonlinear energy-regenerative suspension system with time-delayed feedback control.Firstly,an approximately equivalent dimension reduction system is established by the variable transformation method,and then the stationary probability density function of amplitude is obtained by the stochastic averaging method.Secondly,the precision of the method used in this work is verified by comparing the numerical solutions with the analytical results.Finally,based on the stationary probability density function,the influence of system parameters on stochastic P-bifurcation and the mean output power is discussed.展开更多
In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused...In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused byαparticle ionizing radiation was proposed,and the effects of dead-pixel compensation algorithms were compared and analyzed under different parameter conditions.The experimental results show thatαparticle response signal has highest accuracy at 9 dB gain,with an obvious“target-ring”distribution.With increasing cumulative dose,the CMOS APS pedestal tends to saturation while dead pixels continue increasing.Though some pixel damage recovers through natural annealing,the dead-to-noise ratio increases with irradiation time,reaching 32.54%after 72 h.A hierarchical clustering dead-pixel detection method is proposed,categorizing pixels into two types:those within and outside the response event.A classification compensation strategy combining mean and majority filtering is proposed.This compensation algorithm can address dead-pixel interference without affectingαparticle radiation response data.When iterated multiple times and with integration time exceeding 6.31 ms,the number of dead pixels can be effectively reduced.展开更多
A network time-delay compensation method based on time-delay prediction and implicit proportional-integral-based generalized predictive controller(PIGPC) is proposed. The least squares support vector machine(LSSVM) is...A network time-delay compensation method based on time-delay prediction and implicit proportional-integral-based generalized predictive controller(PIGPC) is proposed. The least squares support vector machine(LSSVM) is used to predict the current time-delay, the parameters of the least squares support vector machine are optimized by particle swarm optimization(PSO) algorithm,and the predicted time-delay is used instead of the actual time-delay as the parameters of the network time-delay compensation controller. In order to improve the compensation effect of implicit generalized predictive controller(GPC), this paper puts forward an implicit generalized predictive control algorithm with proportional-integral-based(PI) structure and designs the controller based on implicit PIGPC. Through the simulation results, the effectiveness of this design in the paper is verified.展开更多
A passive heave compensator is designed to enhance the operation safety of a 4.5 km remotely operated vehicle (ROV).This paper proposes a novel idea of designing a compensator with relatively low natural period to opt...A passive heave compensator is designed to enhance the operation safety of a 4.5 km remotely operated vehicle (ROV).This paper proposes a novel idea of designing a compensator with relatively low natural period to optimize gas volume and while adding a special device to remove the problem of ineffectiveness and resonance in long seas.Numerical simulations are done based on serious dynamic model of the whole system,including the compensator,the umbilical tether and the vehicle,solved by the fourth-order Runge-Kutta scheme.The compensator provides great attenuation of motion and tension in most sea states.As the working depth increases,the system natural period decreases,resulting in the occurrence of risk of resonance.By regulating the system damping,the compensator can be effective in these situations.展开更多
Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic disto...Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion （THD） is greatly reduced. The weights of filter are adjusted on-line according to the control error by using least-mean-square （LMS） algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator （AFC） control scheme展开更多
A novel fuzzy logic compensating (FLC) scheme is proposed to enhance theconventional computed-torque control (CTC) structure of manipulators The control scheme is based onthe combination of a classical CTC and FLC, an...A novel fuzzy logic compensating (FLC) scheme is proposed to enhance theconventional computed-torque control (CTC) structure of manipulators The control scheme is based onthe combination of a classical CTC and FLC, and the resulting control scheme has a simple structurewith improved robustness. Further improvement of the performance of the FLC scheme is achievedthrough automatic tuning of a weight parameter a leading to a self-tuning fuzzy logic compensator,so the system uncertainty can be compensated very well. By taking into account the full nonlinearnature of the robotic dynamics, the overall closed-loop system is shown to be asymptotically stable.Experimental results demonstrate the effectiveness of the computed torque and fuzzy compensationscheme to control a manipulator during a trajectory tracking task.展开更多
CHC Trailing suction hopper dredgers (TSHD) have been widely used in dredging industry. In order to simulate the dredging process accurately, a mathematical model for a swell compensator used in TSHD is proposed, and ...CHC Trailing suction hopper dredgers (TSHD) have been widely used in dredging industry. In order to simulate the dredging process accurately, a mathematical model for a swell compensator used in TSHD is proposed, and a friendly simulation model based on the Automated Dynamic Analysis of Mechanical Systems (ADAMS) is built to test and validate the mathematical model for the swell compensator. The factors influencing the dynamic behavior of the TSHD suction pipe system, such as the mo-tion of the vessel in an unquiet situation with different water current velocities, seabed profiles, seabed soil hardness and the forces acting on the suction pipe system, have been taken into consideration. The simulation results show that they fit in with the operat-ing practice qualitatively.展开更多
In order to improve the Power Quality(PQ)of traction power supply system and reduce the power rating and operation cost of compensator,a Static VAR Compensator(SVC)integrated Railway Power Conditioner(RPC)is presented...In order to improve the Power Quality(PQ)of traction power supply system and reduce the power rating and operation cost of compensator,a Static VAR Compensator(SVC)integrated Railway Power Conditioner(RPC)is presented in this paper.RPC is a widely used device in the AC electrified railway systems to enhance the PQ indices of the main network.The next generation of this equipment is Active Power Quality Compensator(APQC).The major concern of these compensators is their high kVA rating.In this paper,a hybrid technique is proposed to solve aforementioned problems.A combination of SVC as an auxiliary device is employed together with the main compensators,i.e.,RPC and APQC that leads on to the reduction of power rating of the main compensators.The use of proposed scheme will cause to reduce significantly the initial investment cost of compensation system.The main compensators are only utilized to balance active powers of two adjacent feeder sections and suppress harmonic currents.The SVCs are used to compensate reactive power and suppress the third and fifth harmonic currents.In this paper firstly,the PQ compensation procedure in AC electrified railway is analyzed step by step.Then,the control strategies for SVC and the main compensators are presented.Finally,a simulation is fulfilled using Matlab/Simulink software to verify the effectiveness and validity of the proposed scheme and compensation strategy and also demonstrate that this technique could compensate all PQ problems.展开更多
This paper investigates the problem of real-time estimation for one kind of linear time invariant systems which subject to limited communication capacity. The communication limitations include signal transmission dela...This paper investigates the problem of real-time estimation for one kind of linear time invariant systems which subject to limited communication capacity. The communication limitations include signal transmission delay, the out-of-sequence measurements and data packet dropout, which appear typically in a network environment. The kernel of filter design is equally to formularize the traditional Kalman filter as one linear weighted summation which is composed of the initial state estimate and all sequential sampled measurements. For it can adapt aforementioned information limitations, the linear weighted summation is then decomposed into two stages. One is a predict-estimator composed by all reached measurements, another is one compensator constructed by those time-delayed data. In the network environment, there are obvious differences between the new hybrid filter and those existing delayed Kalman filters. For example, the novel filter can be optimal in the sense of linear minimum mean square error as soon as all measurements available and has the lowest running time than these existing delayed filters. One simulation, including two cases, is utilized to illustrate the design procedures proposed in this paper.展开更多
In this paper, a delay-dependent anti-windup compensator is designed for wide-area power systems to enhance the damping of inter-area low-frequency oscillations in the presence of time-varying delays and actuator satu...In this paper, a delay-dependent anti-windup compensator is designed for wide-area power systems to enhance the damping of inter-area low-frequency oscillations in the presence of time-varying delays and actuator saturation using an indirect approach. In this approach, first, a conventional wide-area damping controller is designed by using output feedback with regional pole placement approach without considering time-varying delays and actuator saturation. Then to mitigate the effect of both time-varying delays and actuator saturation, an add-on delay-dependent anti-windup compensator is designed. Based on generalized sector conditions, less conservative delay-dependent sufficient conditions are derived in the form of a linear matrix inequality(LMI) to guarantee the asymptotic stability of the closedloop system in the presence of time-varying delays and actuator saturation by using Lyapunov-Krasovskii functional and Jensen integral inequality. Based on sufficient conditions, the LMI-based optimization problem is formulated and solved to obtain the compensator gain which maximizes the estimation of the region of attraction and minimizes the upper bound of-gain. Nonlinear simulations are performed first using MATLAB/Simulink on a two-area four-machine power system to evaluate the performance of the proposed controller for two operating conditions, e.g.,3-phase to ground fault and generator 1 terminal voltage variation. Then the proposed controller is implemented in real-time on an OPAL-RT digital simulator. From the results obtained it is verified that the proposed controller provides sufficient damping to the inter-area oscillations in the presence of time-varying delays and actuator saturation and maximizes the estimation of the region of attraction.展开更多
We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg gratin...We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg grating is optimally designed and used to compensate for the entire time-delays of the quantized pulses precisely. Simulation results show that the compensated coding pulses are well synchronized with a time difference less than 3.3 ps, which can support a maximum sampling rate of 151.52 GSa/s. The proposed scheme can efficiently reduce the structure complexity and cost of all-optical analog-to-digital conversion compared to the previous schemes with multiple optical time-delay lines.展开更多
According to the theory of testing aspherical surface by normal aberration compensation method,the designing method of quasi-universal compensator is studied.On the basis of third-order aberration theory,after calcula...According to the theory of testing aspherical surface by normal aberration compensation method,the designing method of quasi-universal compensator is studied.On the basis of third-order aberration theory,after calculating and optimizing with an optical design program,the structure parameters of a compensator are obtained.This new compensator could be used in Twyman-Green interferometer,and in measurement of a certain range of paraboloid ellipsoid and hyperboloid.The compensation accuracy is more than 0.02 λ .展开更多
In this paper, the reduced-order modeling （ROM） technology and its corresponding linear theory are expanded from the linear dynamic system to the nonlinear one, and H∞ control theory is employed in the frequency do...In this paper, the reduced-order modeling （ROM） technology and its corresponding linear theory are expanded from the linear dynamic system to the nonlinear one, and H∞ control theory is employed in the frequency domain to design some nonlinear system＇ s pre-compensator in some special way. The adaptive model inverse control （AMIC）theory coping with nonlinear system is improved as well. Such is the model reference adaptive inverse control with pre-compensator （PCMRAIC）. The aim of that algorithm is to construct a strategy of control as a whole. As a practical example of the application, the nunlerical simulation has been given on matlab software packages. The numerical result is given. The proposed strategy realizes the linearization control of nonlinear dynamic system. And it carries out a good performance to deal with the nonlinear system.展开更多
Unmanned Aero Vehicles (UAV) has become a useful entity for quite a good number of industries and facilities. It is an agile, cost effective and reliable solution for communication, defense, security, delivery, survei...Unmanned Aero Vehicles (UAV) has become a useful entity for quite a good number of industries and facilities. It is an agile, cost effective and reliable solution for communication, defense, security, delivery, surveillance and surveying etc. However, their reliability is dependent on the resilient and stabilizes performance based on control systems embedded behind the body. Therefore, the UAV is majorly dependent upon controller design and the requirement of particular performance parameters. Nevertheless, in modern technologies there is always a room for improvement. In the similar manner a UAV lateral control system was implemented and researched in this study, which has been optimized using Proportional, Integral and Derivative (PID) controller, phase lead compensator and signal constraint controller. The significance of this study is the optimization of the existing UAV controller plant for improving lateral performance and stability. With this UAV community will benefit from designing robust controls using the optimized method utilized in this paper and moreover this will provide sophisticated control to operate in unpredictable environments. It is observed that results obtained for optimized lateral control dynamics using phase lead compensator (PLC) are efficacious than the simple PID feedback gains. However, for optimizing unwanted signals of lateral velocity, yaw rate, and yaw angle modes, PLC were integrated with PID to achieve dynamical stability.展开更多
Based on the analysis, according to the principle of vibration, of the working character of weft tension compensator in needle looms, the paper studied the principle of tension compensation and introduced the idea of ...Based on the analysis, according to the principle of vibration, of the working character of weft tension compensator in needle looms, the paper studied the principle of tension compensation and introduced the idea of compensating coefficient. The paper also discussed some factors affecting the effect of tension compensation.展开更多
Ca_(3-x)(PO_(4))_(2):xTb^(3+)(0.2≤x≤0.4),Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.35 A^(+)(A=Li,Na,K),and Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),yLi^(+)(0.35≤y≤0.455)phosphors were prepared by solid-state reaction.All the p...Ca_(3-x)(PO_(4))_(2):xTb^(3+)(0.2≤x≤0.4),Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.35 A^(+)(A=Li,Na,K),and Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),yLi^(+)(0.35≤y≤0.455)phosphors were prepared by solid-state reaction.All the prepared phosphors formed a rhombohedral unit cell with the R3c space group.To improve the photoluminescence(PL)properties of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor,monovalent charge compensators such as Li^(+),NA^(+),and K^(+)were added to the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.The charge compensators acted as fluxes,so they improved the crystallinity.The excitation and emission properties were significantly improved through the incorporation of charge compensators.In particular,among the charge compensators,Li^(+)ion substantially enhanced the emission intensity and color purity.Furthermore,considering the evaporation of Li_(2)CO_(3)during the annealing process,we optimized the concentration of Li^(+)charge compensator to enhance its PL performance.Impressively,the green emission intensity of the Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.385 Li^(+)phosphor was 260%higher than that of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.We believe that the effect of charge compensators on the PL properties and the optimum concentration of Li^(+)cha rge compensator are useful for the design of phosphors in light-emitting diodes.展开更多
基金This work was supported by the National Natural Science Foundation(No.60274007)the Doctoral Foundation of Education Ministry(No.20010487005)the Academic Foundation of Naval University of Engineering(No.E988).
文摘The stabilization using a stable compensator does not introduce additional unstable zeros into the closed-loop transfer function beyond those of the original plant, so it is a desirable compensator, the price is that the compensator’s order will go up. This note considered the order of stable compensators for a class of time-delay systems. First, it is shown that for single-loop plants with at most one real right-half plane zero, a special upper bound for the minimal order of a strongly stabilizing compensator can be obtained in terms of the plant order; Second, it is shown that approximate unstable pole-zero cancellation does not occur, and the distances between distinct unstable zeroes are bounded below by a positive constant, then it is possible to find an upper bound for the minimal order of a strongly stabilizing compensator.
基金financially supported by the National Natural Science Foundation of China(52102206)the Natural Science Foundation of Beijing Municipality-Shunyi Innovation Collaborative Joint Fund(L247018)+2 种基金the Natural Science Foundation of Beijing Municipality(2254076 and 2252024)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(246Z4412G)the Fundamental Research Funds for the Central Universities(2025MS022,North China Electric Power University)。
文摘Composite cathodes integrating Ni-rich layered oxides and oxide solid electrolytes are essential for highenergy all-solid-state lithium-ion batteries(ASSLBs),yet interfacial degradation during high-temperature co-sintering(>600℃)remains a critical challenge.While surface passivation strategies mitigate reactions below 400℃,their effectiveness diminishes at elevated temperatures due to inability to counteract Li^(+)concentration gradients.Here,we introduce in situ lithium compensators,i.e.,LiOH/Li_(2)CO_(3),into NCM-LATP composite cathodes to dynamically replenish Li^(+)during co-sintering.These additives melt to form transient Li^(+)-rich phases that back-diffuse Li^(+)into NCM lattices,suppressing layered-to-rock salt transitions and stabilizing the interface.Quasi in situ XRD confirms retention of the layered structure at temperature up to 700℃,while electrochemical tests demonstrate a reversible capacity of 222.2 mA h g^(-1)—comparable to NCM before co-sintering—and an impressive 65.3% capacity retention improvement over100 cycles.In contrast,uncompensated cathodes exhibit severe degradation to 96.5 mA h g^(-1)due to Li depletion and resistive Li-Ti-O interphases.This strategy integrates sacrificial chemistry with scalable powder-mixing workflows,achieving a 93.4% reduction in interfacial impedance.By addressing Li^(+)flux homogenization and structural stability,this work provides a practical pathway toward industrialscale fabrication of high-performance ASSLBs.
基金supported by the National Natural Science Foundation of China(Grant No.52105466).
文摘The prediction and compensation control of marine ship motion is crucial for ensuring the safety of offshore wind turbine loading and unloading operations.However,the accuracy of prediction and control is significantly affected by the hysteresis phenomenon in the wave compensation system.To address this issue,a ship heave motion prediction is proposed in this paper on the basis of the Gauss-DeepAR(AR stands for autoregressive recurrent)model and the Hilbert−Huang time-delay compensation control strategy.Initially,the zero upward traveling wave period of the level 4−6 sea state ship heave motion is analyzed,which serves as the input sliding window for the Gauss-DeepAR prediction model,and probability predictions at different wave direction angles are conducted.Next,considering the hysteresis characteristics of the ship heave motion compensation platform,the Hilbert−Huang transform is employed to analyze and calculate the hysteresis delay of the compensation platform.After the optimal control action value is subsequently calculated,simulations and hardware platform tests are conducted.The simulation results demonstrated that the Gauss-DeepAR model outperforms autoregressive integrated moving average model(ARIMA),support vector machine(SVM),and longshort-term memory(LSTM)in predicting non-independent identically distributed datasets at a 90°wave direction angle in the level 4−6 sea states.Furthermore,the model has good predictive performance and generalizability for non-independent and non-uniformly distributed datasets at a 180°wave direction angle.The hardware platform compensation test results revealed that the Hilbert–Huang method has an outstanding effect on determining the hysteretic delay and selecting the optimal control action value,and the compensation efficiency was higher than 90%in the level 4−6 sea states.
基金Supported by National Natural Science Foundation of P.R.China (60474045)973 Program of P.R.China (2002CB312200)the project sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry, Zhejiang Province, and Zhejiang University
文摘Systems that are subject to both time-delay in state and input saturation are considered. We synthesize the anti-windup gain to enlarge the estimation of domain of attraction while guaranteeing the stability of the closed-loop system. An ellipsoid and a polyhedral set are used to bound the state of the system, which make a new sector condition valid. Other than an iterative algorithm, a direct designing algorithm is derived to compute the anti-windup compensator gain, which reduces the conservatism greatly. We analyze the delay-independent and delay-dependent cases, respectively. Finally, an optimization algorithm in the form of LMIs is constructed to compute the compensator gain which maximizes the estimation of domain of attraction. Numerical examples are presented to demonstrate the effectiveness of our approach.
基金Project supported by the National Natural Science Foundation of China(Grant No.12002089)the Science and Technology Projects in Guangzhou(Grant No.2023A04J1323)UKRI Horizon Europe Guarantee(Marie SklodowskaCurie Fellowship)(Grant No.EP/Y016130/1)。
文摘Energy-regenerative suspension combined with piezoelectric and electromagnetic transduction has evolved into a core technological pathway in advancing automotive design paradigms.With the aim of improving energy harvesting performance,time-delayed feedback control is widely used in an energy-regenerative suspension system under different external disturbances in this paper.Meanwhile,limited research has addressed the stochastic dynamics of time-delayed nonlinear energy-regenerative suspension systems.Different from previous studies,this work studies the stochastic response and P-bifurcation of the nonlinear energy-regenerative suspension system with time-delayed feedback control.Firstly,an approximately equivalent dimension reduction system is established by the variable transformation method,and then the stationary probability density function of amplitude is obtained by the stochastic averaging method.Secondly,the precision of the method used in this work is verified by comparing the numerical solutions with the analytical results.Finally,based on the stationary probability density function,the influence of system parameters on stochastic P-bifurcation and the mean output power is discussed.
基金supported by the National Natural Science Foundation of China(No.11905102)Hunan Provincial Postgraduate Research and Innovation Project(No.QL20230234)。
文摘In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused byαparticle ionizing radiation was proposed,and the effects of dead-pixel compensation algorithms were compared and analyzed under different parameter conditions.The experimental results show thatαparticle response signal has highest accuracy at 9 dB gain,with an obvious“target-ring”distribution.With increasing cumulative dose,the CMOS APS pedestal tends to saturation while dead pixels continue increasing.Though some pixel damage recovers through natural annealing,the dead-to-noise ratio increases with irradiation time,reaching 32.54%after 72 h.A hierarchical clustering dead-pixel detection method is proposed,categorizing pixels into two types:those within and outside the response event.A classification compensation strategy combining mean and majority filtering is proposed.This compensation algorithm can address dead-pixel interference without affectingαparticle radiation response data.When iterated multiple times and with integration time exceeding 6.31 ms,the number of dead pixels can be effectively reduced.
基金supported by National Natural Science Foundation of China(No.61034005)Liaoning Province Doctor Startup Fund(No.20141070)
文摘A network time-delay compensation method based on time-delay prediction and implicit proportional-integral-based generalized predictive controller(PIGPC) is proposed. The least squares support vector machine(LSSVM) is used to predict the current time-delay, the parameters of the least squares support vector machine are optimized by particle swarm optimization(PSO) algorithm,and the predicted time-delay is used instead of the actual time-delay as the parameters of the network time-delay compensation controller. In order to improve the compensation effect of implicit generalized predictive controller(GPC), this paper puts forward an implicit generalized predictive control algorithm with proportional-integral-based(PI) structure and designs the controller based on implicit PIGPC. Through the simulation results, the effectiveness of this design in the paper is verified.
基金the National High Technology Research and Development Program (863) of China(No. 2008AA092301-1)the National Natural Science Foundation of China(No. 50909061)the PH. D. Programs Foundation of Ministry of Education of China(No. 20070248103)
文摘A passive heave compensator is designed to enhance the operation safety of a 4.5 km remotely operated vehicle (ROV).This paper proposes a novel idea of designing a compensator with relatively low natural period to optimize gas volume and while adding a special device to remove the problem of ineffectiveness and resonance in long seas.Numerical simulations are done based on serious dynamic model of the whole system,including the compensator,the umbilical tether and the vehicle,solved by the fourth-order Runge-Kutta scheme.The compensator provides great attenuation of motion and tension in most sea states.As the working depth increases,the system natural period decreases,resulting in the occurrence of risk of resonance.By regulating the system damping,the compensator can be effective in these situations.
文摘Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion （THD） is greatly reduced. The weights of filter are adjusted on-line according to the control error by using least-mean-square （LMS） algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator （AFC） control scheme
文摘A novel fuzzy logic compensating (FLC) scheme is proposed to enhance theconventional computed-torque control (CTC) structure of manipulators The control scheme is based onthe combination of a classical CTC and FLC, and the resulting control scheme has a simple structurewith improved robustness. Further improvement of the performance of the FLC scheme is achievedthrough automatic tuning of a weight parameter a leading to a self-tuning fuzzy logic compensator,so the system uncertainty can be compensated very well. By taking into account the full nonlinearnature of the robotic dynamics, the overall closed-loop system is shown to be asymptotically stable.Experimental results demonstrate the effectiveness of the computed torque and fuzzy compensationscheme to control a manipulator during a trajectory tracking task.
文摘CHC Trailing suction hopper dredgers (TSHD) have been widely used in dredging industry. In order to simulate the dredging process accurately, a mathematical model for a swell compensator used in TSHD is proposed, and a friendly simulation model based on the Automated Dynamic Analysis of Mechanical Systems (ADAMS) is built to test and validate the mathematical model for the swell compensator. The factors influencing the dynamic behavior of the TSHD suction pipe system, such as the mo-tion of the vessel in an unquiet situation with different water current velocities, seabed profiles, seabed soil hardness and the forces acting on the suction pipe system, have been taken into consideration. The simulation results show that they fit in with the operat-ing practice qualitatively.
文摘In order to improve the Power Quality(PQ)of traction power supply system and reduce the power rating and operation cost of compensator,a Static VAR Compensator(SVC)integrated Railway Power Conditioner(RPC)is presented in this paper.RPC is a widely used device in the AC electrified railway systems to enhance the PQ indices of the main network.The next generation of this equipment is Active Power Quality Compensator(APQC).The major concern of these compensators is their high kVA rating.In this paper,a hybrid technique is proposed to solve aforementioned problems.A combination of SVC as an auxiliary device is employed together with the main compensators,i.e.,RPC and APQC that leads on to the reduction of power rating of the main compensators.The use of proposed scheme will cause to reduce significantly the initial investment cost of compensation system.The main compensators are only utilized to balance active powers of two adjacent feeder sections and suppress harmonic currents.The SVCs are used to compensate reactive power and suppress the third and fifth harmonic currents.In this paper firstly,the PQ compensation procedure in AC electrified railway is analyzed step by step.Then,the control strategies for SVC and the main compensators are presented.Finally,a simulation is fulfilled using Matlab/Simulink software to verify the effectiveness and validity of the proposed scheme and compensation strategy and also demonstrate that this technique could compensate all PQ problems.
基金Supported by the National Natural Science Foundation of China (No.60804064,60772006)
文摘This paper investigates the problem of real-time estimation for one kind of linear time invariant systems which subject to limited communication capacity. The communication limitations include signal transmission delay, the out-of-sequence measurements and data packet dropout, which appear typically in a network environment. The kernel of filter design is equally to formularize the traditional Kalman filter as one linear weighted summation which is composed of the initial state estimate and all sequential sampled measurements. For it can adapt aforementioned information limitations, the linear weighted summation is then decomposed into two stages. One is a predict-estimator composed by all reached measurements, another is one compensator constructed by those time-delayed data. In the network environment, there are obvious differences between the new hybrid filter and those existing delayed Kalman filters. For example, the novel filter can be optimal in the sense of linear minimum mean square error as soon as all measurements available and has the lowest running time than these existing delayed filters. One simulation, including two cases, is utilized to illustrate the design procedures proposed in this paper.
文摘In this paper, a delay-dependent anti-windup compensator is designed for wide-area power systems to enhance the damping of inter-area low-frequency oscillations in the presence of time-varying delays and actuator saturation using an indirect approach. In this approach, first, a conventional wide-area damping controller is designed by using output feedback with regional pole placement approach without considering time-varying delays and actuator saturation. Then to mitigate the effect of both time-varying delays and actuator saturation, an add-on delay-dependent anti-windup compensator is designed. Based on generalized sector conditions, less conservative delay-dependent sufficient conditions are derived in the form of a linear matrix inequality(LMI) to guarantee the asymptotic stability of the closedloop system in the presence of time-varying delays and actuator saturation by using Lyapunov-Krasovskii functional and Jensen integral inequality. Based on sufficient conditions, the LMI-based optimization problem is formulated and solved to obtain the compensator gain which maximizes the estimation of the region of attraction and minimizes the upper bound of-gain. Nonlinear simulations are performed first using MATLAB/Simulink on a two-area four-machine power system to evaluate the performance of the proposed controller for two operating conditions, e.g.,3-phase to ground fault and generator 1 terminal voltage variation. Then the proposed controller is implemented in real-time on an OPAL-RT digital simulator. From the results obtained it is verified that the proposed controller provides sufficient damping to the inter-area oscillations in the presence of time-varying delays and actuator saturation and maximizes the estimation of the region of attraction.
基金Project supported by the National Basic Research Program,China(Grant Nos.2010CB327605 and 2010CB328300)the National High-Technology Research and Development Program of China(Grant No.2013AA031501)+7 种基金the National Natural Science Foundation of China(Grant No.61307109)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120005120021)the Fundamental Research Funds for the Central Universities,China(Grant No.2013RC1202)the Program for New Century Excellent Talents in University,China(Grant No.NECT-11-0596)the Beijing Nova Program,China(Grant No.2011066)the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications) Chinathe China Postdoctoral Science Foundation(Grant No.2012M511826)the Postdoctoral Science Foundation of Guangdong Province,China(Grant No.244331)
文摘We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg grating is optimally designed and used to compensate for the entire time-delays of the quantized pulses precisely. Simulation results show that the compensated coding pulses are well synchronized with a time difference less than 3.3 ps, which can support a maximum sampling rate of 151.52 GSa/s. The proposed scheme can efficiently reduce the structure complexity and cost of all-optical analog-to-digital conversion compared to the previous schemes with multiple optical time-delay lines.
文摘According to the theory of testing aspherical surface by normal aberration compensation method,the designing method of quasi-universal compensator is studied.On the basis of third-order aberration theory,after calculating and optimizing with an optical design program,the structure parameters of a compensator are obtained.This new compensator could be used in Twyman-Green interferometer,and in measurement of a certain range of paraboloid ellipsoid and hyperboloid.The compensation accuracy is more than 0.02 λ .
基金Supported by the National Defense Base Research Foundation (No. 40104030102),and the Postdoctoral Foundation of Heilongjiang Province
文摘In this paper, the reduced-order modeling （ROM） technology and its corresponding linear theory are expanded from the linear dynamic system to the nonlinear one, and H∞ control theory is employed in the frequency domain to design some nonlinear system＇ s pre-compensator in some special way. The adaptive model inverse control （AMIC）theory coping with nonlinear system is improved as well. Such is the model reference adaptive inverse control with pre-compensator （PCMRAIC）. The aim of that algorithm is to construct a strategy of control as a whole. As a practical example of the application, the nunlerical simulation has been given on matlab software packages. The numerical result is given. The proposed strategy realizes the linearization control of nonlinear dynamic system. And it carries out a good performance to deal with the nonlinear system.
文摘Unmanned Aero Vehicles (UAV) has become a useful entity for quite a good number of industries and facilities. It is an agile, cost effective and reliable solution for communication, defense, security, delivery, surveillance and surveying etc. However, their reliability is dependent on the resilient and stabilizes performance based on control systems embedded behind the body. Therefore, the UAV is majorly dependent upon controller design and the requirement of particular performance parameters. Nevertheless, in modern technologies there is always a room for improvement. In the similar manner a UAV lateral control system was implemented and researched in this study, which has been optimized using Proportional, Integral and Derivative (PID) controller, phase lead compensator and signal constraint controller. The significance of this study is the optimization of the existing UAV controller plant for improving lateral performance and stability. With this UAV community will benefit from designing robust controls using the optimized method utilized in this paper and moreover this will provide sophisticated control to operate in unpredictable environments. It is observed that results obtained for optimized lateral control dynamics using phase lead compensator (PLC) are efficacious than the simple PID feedback gains. However, for optimizing unwanted signals of lateral velocity, yaw rate, and yaw angle modes, PLC were integrated with PID to achieve dynamical stability.
文摘Based on the analysis, according to the principle of vibration, of the working character of weft tension compensator in needle looms, the paper studied the principle of tension compensation and introduced the idea of compensating coefficient. The paper also discussed some factors affecting the effect of tension compensation.
基金financially supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea government Ministry of Trade,Industry&Energy(No.20184030202260)。
文摘Ca_(3-x)(PO_(4))_(2):xTb^(3+)(0.2≤x≤0.4),Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.35 A^(+)(A=Li,Na,K),and Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),yLi^(+)(0.35≤y≤0.455)phosphors were prepared by solid-state reaction.All the prepared phosphors formed a rhombohedral unit cell with the R3c space group.To improve the photoluminescence(PL)properties of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor,monovalent charge compensators such as Li^(+),NA^(+),and K^(+)were added to the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.The charge compensators acted as fluxes,so they improved the crystallinity.The excitation and emission properties were significantly improved through the incorporation of charge compensators.In particular,among the charge compensators,Li^(+)ion substantially enhanced the emission intensity and color purity.Furthermore,considering the evaporation of Li_(2)CO_(3)during the annealing process,we optimized the concentration of Li^(+)charge compensator to enhance its PL performance.Impressively,the green emission intensity of the Ca_(2.3)(PO_(4))_(2):0.35 Tb^(3+),0.385 Li^(+)phosphor was 260%higher than that of the Ca_(2.65)(PO_(4))_(2):0.35 Tb^(3+)phosphor.We believe that the effect of charge compensators on the PL properties and the optimum concentration of Li^(+)cha rge compensator are useful for the design of phosphors in light-emitting diodes.
