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
Urbanization alters vegetation productivity by both direct(ωd)and indirect(ω_(i))effects.The direct effect is from the change of vegetated area indicated by impervious surface intensity(ISI),while indirect effects a...Urbanization alters vegetation productivity by both direct(ωd)and indirect(ω_(i))effects.The direct effect is from the change of vegetated area indicated by impervious surface intensity(ISI),while indirect effects arise from changes in urban environmental factors,such as near-surface air temperatures,precipitation,urban heat island(UHI)intensity,and population density(POP).The respective contributions ofω_(d) andω_(i) to vegetation net primary productivity(NPP)under various phases of urbanization are not well quantified.Using multisource remote-sensing data from 1990 to 2020,we analyzed the spatiotemporal variation in urban expansion and the effect thatω_(d) andω_(i) had on NPP in the megalopolis of Beijing,China,over 5-year intervals.During this period,Beijing underwent significant planar expansion rates of about 58.9 km^(2)/yr.Annual mean loss of NPP byω_(d) was estimated to be about 77.1 g C/(m^(2)·yr)during the 1990-2020 period,while annual mean improvement to NPP byω_(i) amounted to an increase of 28.9 g C/(m^(2)·yr).The NPP losses were partially offset by NPP improvements in the order of 18.6%-69.3%.The impact of forcing variables on NPP varied spatially.Air temperature,precipitation,UHI,POP,and ISI explained about 13.8%,23.2%,23.7%,14.7%,and 24.6%of the spatial variation in NPP.The impact of air temperature on NPP was related to available moisture,negatively affecting NPP in regions with water deficits.Our findings demonstrate the dual impact of urbanization on vegetation and underscore the necessity for spatially adaptive ecological management strategies in regions experiencing rapid urban growth.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
The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestratio...The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestration in grasslands remains unclear.Based on panel data from prefecture-level cities in the Yellow River Basin(YRB)from 2000 to 2020,this study explored the effects of the GECP on grassland carbon sequestration in the YRB and its heterogeneity using a time-varying difference-in-differences(TV-DID)model.Subsequently,we predicted changes in carbon sequestration in grasslands under the influence of the GECP from 2021 to 2040 using a simulation.The main conclusions are as follows:First,the implementation of the GECP promoted carbon sequestration in grasslands.This conclusion was validated after conducting a series of robustness tests.Moreover,the effects of the GECP were heterogeneous across different geographical locations,highway densities,and grassland areas.Finally,the simulation results indicated that over the next 20 years,grassland carbon sequestration will generally increase but exhibit cyclical changes.The government should align the principles and objectives of the GECP with local geographic conditions,resource availability,and socio-economic development.It must formulate and implement tailored policies that maximize the ecological protection benefits of the GECP and promote carbon sequestration in the grasslands of the YRB.展开更多
Measuring cross sections of nuclear reactions,such as the so-called“Holy Grail”reaction,^(12)C(σ,γ)^(16)O,is essential for understanding stellar nucleosynthesis but presents significant challenges due to extremely...Measuring cross sections of nuclear reactions,such as the so-called“Holy Grail”reaction,^(12)C(σ,γ)^(16)O,is essential for understanding stellar nucleosynthesis but presents significant challenges due to extremely low cross sections.Key challenges include significant energy loss as ions penetrate the target material,limiting measurements to thin target layers.To overcome these obstacles,we propose a novel method,the in-target energy loss compensating(eLOC)method,specifically designed for gas targets,which utilizes a gas-filled magnetic field and accelerating electric fields to compensate for ion energy loss in the target.Simulations show that this approach significantly enhances the effective target thickness by over 140 times in the case of the“Holy Grail”reaction with an inverse-kinematics setup.This eLOC method may provide a powerful new tool for obtaining critical data in nuclear astrophysics,thereby advancing our understanding of stellar nucleosynthesis and the origins of elements in the universe,as well as benefiting other related fields such as isotope production.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
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
This work presents a fuzzy based methodology for distribution system feeder reconfiguration considering DSTATCOM with an objective of minimizing real power loss and operating cost. Installation costs of DSTATCOM devic...This work presents a fuzzy based methodology for distribution system feeder reconfiguration considering DSTATCOM with an objective of minimizing real power loss and operating cost. Installation costs of DSTATCOM devices and the cost of system operation, namely, energy loss cost due to both reconfiguration and DSTATCOM placement, are combined to form the objective function to be minimized. The distribution system tie switches, DSTATCOM location and size have been optimally determined to obtain an appropriate operational condition. In the proposed approach, the fuzzy membership function of loss sensitivity is used for the selection of weak nodes in the power system for the placement of DSTATCOM and the optimal parameter settings of the DFACTS device along with optimal selection of tie switches in reconfiguration process are governed by genetic algorithm(GA). Simulation results on IEEE 33-bus and IEEE 69-bus test systems concluded that the combinatorial method using DSTATCOM and reconfiguration is preferable to reduce power losses to 34.44% for 33-bus system and to 45.43% for 69-bus system.展开更多
Presents the design of a micro boring servo system. A piezoelectric actuator is employed to compensate the deflection errors of the cutter in the radial direction to reduce the force induced errors in the workpiece. I...Presents the design of a micro boring servo system. A piezoelectric actuator is employed to compensate the deflection errors of the cutter in the radial direction to reduce the force induced errors in the workpiece. In order to bore small and deep holes, the boring bar is designed with a new structure consisting of two concentric bars, one being used for error measuring and the other for error compensation. As a result, the size of the micro boring bar is not affected even after the piezoelectric actuator and strain gauges have been incorporated. The outer diameter of the boring bar used is 16 mm and the length to diameter ratio is greater than 9. A Forecasting Compensatory Control (FCC) technique is adopted in this system for error prediction and error compensation. The off line forecasting compensatory control simulation and on line cutting results have verified that the roundness form errors in the workpiece can be reduced up to 60 percent with the developed micro boring servo system.展开更多
Presents a systematic design method of reduced order dynamical compensator via the parametric representations of eigenstructure assignment for linear system, which provides maximum degree of freedom, and can be easily...Presents a systematic design method of reduced order dynamical compensator via the parametric representations of eigenstructure assignment for linear system, which provides maximum degree of freedom, and can be easily used for the design of a linear system with unknown inputs under some conditions. Even when these conditions are not satisfied, the lower order dynamical compensator can also be designed under some relaxed conditions. Some examples illustrate that the method is neat, simple and effective.展开更多
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 Key Research and Develop-ment Program of China(No.2020YFA0608100)the National Nat-ural Science Foundation of China(Nos.32071842 and 32101588).
文摘Urbanization alters vegetation productivity by both direct(ωd)and indirect(ω_(i))effects.The direct effect is from the change of vegetated area indicated by impervious surface intensity(ISI),while indirect effects arise from changes in urban environmental factors,such as near-surface air temperatures,precipitation,urban heat island(UHI)intensity,and population density(POP).The respective contributions ofω_(d) andω_(i) to vegetation net primary productivity(NPP)under various phases of urbanization are not well quantified.Using multisource remote-sensing data from 1990 to 2020,we analyzed the spatiotemporal variation in urban expansion and the effect thatω_(d) andω_(i) had on NPP in the megalopolis of Beijing,China,over 5-year intervals.During this period,Beijing underwent significant planar expansion rates of about 58.9 km^(2)/yr.Annual mean loss of NPP byω_(d) was estimated to be about 77.1 g C/(m^(2)·yr)during the 1990-2020 period,while annual mean improvement to NPP byω_(i) amounted to an increase of 28.9 g C/(m^(2)·yr).The NPP losses were partially offset by NPP improvements in the order of 18.6%-69.3%.The impact of forcing variables on NPP varied spatially.Air temperature,precipitation,UHI,POP,and ISI explained about 13.8%,23.2%,23.7%,14.7%,and 24.6%of the spatial variation in NPP.The impact of air temperature on NPP was related to available moisture,negatively affecting NPP in regions with water deficits.Our findings demonstrate the dual impact of urbanization on vegetation and underscore the necessity for spatially adaptive ecological management strategies in regions experiencing rapid urban growth.
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 the National Natural Science Foundation of China[Grant No.71773091]the Graduate Student Science and Technology Innovation Program of College of Economics and Management[Grant No.JGYJSCXXM202308].
文摘The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestration in grasslands remains unclear.Based on panel data from prefecture-level cities in the Yellow River Basin(YRB)from 2000 to 2020,this study explored the effects of the GECP on grassland carbon sequestration in the YRB and its heterogeneity using a time-varying difference-in-differences(TV-DID)model.Subsequently,we predicted changes in carbon sequestration in grasslands under the influence of the GECP from 2021 to 2040 using a simulation.The main conclusions are as follows:First,the implementation of the GECP promoted carbon sequestration in grasslands.This conclusion was validated after conducting a series of robustness tests.Moreover,the effects of the GECP were heterogeneous across different geographical locations,highway densities,and grassland areas.Finally,the simulation results indicated that over the next 20 years,grassland carbon sequestration will generally increase but exhibit cyclical changes.The government should align the principles and objectives of the GECP with local geographic conditions,resource availability,and socio-economic development.It must formulate and implement tailored policies that maximize the ecological protection benefits of the GECP and promote carbon sequestration in the grasslands of the YRB.
基金supported by the the National Key R&D Program of China (Grant Nos.2023YFA1606900 and 2022YFA1602301)the National Natural Science Foundation of China (Grant Nos.12235003,12435010,and 12147101)+3 种基金the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2020B0301030008)the STCSM (Grant No.23590780100)the Natural Science Foundation of Shanghai (Grant No.23JC1400200)the China Postdoctoral Science Foundation (Grant No.2024M760483)。
文摘Measuring cross sections of nuclear reactions,such as the so-called“Holy Grail”reaction,^(12)C(σ,γ)^(16)O,is essential for understanding stellar nucleosynthesis but presents significant challenges due to extremely low cross sections.Key challenges include significant energy loss as ions penetrate the target material,limiting measurements to thin target layers.To overcome these obstacles,we propose a novel method,the in-target energy loss compensating(eLOC)method,specifically designed for gas targets,which utilizes a gas-filled magnetic field and accelerating electric fields to compensate for ion energy loss in the target.Simulations show that this approach significantly enhances the effective target thickness by over 140 times in the case of the“Holy Grail”reaction with an inverse-kinematics setup.This eLOC method may provide a powerful new tool for obtaining critical data in nuclear astrophysics,thereby advancing our understanding of stellar nucleosynthesis and the origins of elements in the universe,as well as benefiting other related fields such as isotope production.
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.
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.
基金supported by Borujerd Branch,Islamic Azad University Iran
文摘This work presents a fuzzy based methodology for distribution system feeder reconfiguration considering DSTATCOM with an objective of minimizing real power loss and operating cost. Installation costs of DSTATCOM devices and the cost of system operation, namely, energy loss cost due to both reconfiguration and DSTATCOM placement, are combined to form the objective function to be minimized. The distribution system tie switches, DSTATCOM location and size have been optimally determined to obtain an appropriate operational condition. In the proposed approach, the fuzzy membership function of loss sensitivity is used for the selection of weak nodes in the power system for the placement of DSTATCOM and the optimal parameter settings of the DFACTS device along with optimal selection of tie switches in reconfiguration process are governed by genetic algorithm(GA). Simulation results on IEEE 33-bus and IEEE 69-bus test systems concluded that the combinatorial method using DSTATCOM and reconfiguration is preferable to reduce power losses to 34.44% for 33-bus system and to 45.43% for 69-bus system.
文摘Presents the design of a micro boring servo system. A piezoelectric actuator is employed to compensate the deflection errors of the cutter in the radial direction to reduce the force induced errors in the workpiece. In order to bore small and deep holes, the boring bar is designed with a new structure consisting of two concentric bars, one being used for error measuring and the other for error compensation. As a result, the size of the micro boring bar is not affected even after the piezoelectric actuator and strain gauges have been incorporated. The outer diameter of the boring bar used is 16 mm and the length to diameter ratio is greater than 9. A Forecasting Compensatory Control (FCC) technique is adopted in this system for error prediction and error compensation. The off line forecasting compensatory control simulation and on line cutting results have verified that the roundness form errors in the workpiece can be reduced up to 60 percent with the developed micro boring servo system.
文摘Presents a systematic design method of reduced order dynamical compensator via the parametric representations of eigenstructure assignment for linear system, which provides maximum degree of freedom, and can be easily used for the design of a linear system with unknown inputs under some conditions. Even when these conditions are not satisfied, the lower order dynamical compensator can also be designed under some relaxed conditions. Some examples illustrate that the method is neat, simple and effective.
