Prescribed Performance Tracking Control of Time-Delay Nonlinear Systems With Output Constraints

The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requirements, i.e., boundedness and the local Lipschitz condition, are assumed for the allowable time delays. Moreover, we focus on the case where the reference is unknown beforehand, which renders the standard prescribed performance control designs under output constraints infeasible. To conquer these challenges, a novel robust prescribed performance control approach is put forward in this paper.Herein, a reverse tuning function is skillfully constructed and automatically generates a performance envelop for the tracking error. In addition, a unified performance analysis framework based on proof by contradiction and the barrier function is established to reveal the inherent robustness of the control system against the time delays. It turns out that the system output tracks the reference with a preassigned settling time and good accuracy,without constraint violations. A comparative simulation on a two-stage chemical reactor is carried out to illustrate the above theoretical findings.

A frequency servo SoC with output power stabilization loop technology for miniaturized atomic clocks

A frequency servo system-on-chip(FS-SoC)featuring output power stabilization technology is introduced in this study for high-precision and miniaturized cesium(Cs)atomic clocks.The proposed power stabilization loop(PSL)technique,incorporating an off-chip power detector(PD),ensures that the output power of the FS-SoC remains stable,mitigating the impact of power fluctuations on the atomic clock's stability.Additionally,a one-pulse-per-second(1PPS)is employed to syn-chronize the clock with GPS.Fabricated using 65 nm CMOS technology,the measured phase noise of the FS-SoC stands at-69.5 dBc/Hz@100 Hz offset and-83.9 dBc/Hz@1 kHz offset,accompanied by a power dissipation of 19.7 mW.The Cs atomic clock employing the proposed FS-SoC and PSL obtains an Allan deviation of 1.7×10^(-11) with 1-s averaging time.

Adaptive Optimal Discrete-Time Output-Feedback Using an Internal Model Principle and Adaptive Dynamic Programming

In order to address the output feedback issue for linear discrete-time systems, this work suggests a brand-new adaptive dynamic programming(ADP) technique based on the internal model principle(IMP). The proposed method, termed as IMP-ADP, does not require complete state feedback-merely the measurement of input and output data. More specifically, based on the IMP, the output control problem can first be converted into a stabilization problem. We then design an observer to reproduce the full state of the system by measuring the inputs and outputs. Moreover, this technique includes both a policy iteration algorithm and a value iteration algorithm to determine the optimal feedback gain without using a dynamic system model. It is important that with this concept one does not need to solve the regulator equation. Finally, this control method was tested on an inverter system of grid-connected LCLs to demonstrate that the proposed method provides the desired performance in terms of both tracking and disturbance rejection.

Achieving Given Precision Within Prescribed Time yet With Guaranteed Transient Behavior via Output Based Event-Triggered Control

It is interesting yet nontrivial to achieve given control precision within user-assignable time for uncertain nonlinear systems.The underlying problem becomes even more challenging if the transient behavior also needs to be accommodated and only system output is available for feedback.Several key design innovations are proposed to circumvent the aforementioned technical difficulties,including the employment of state estimation filters with event-triggered mechanism,the construction of a novel performance scaling function and an error transformation.In contrast to most existing performance based works where the stability is contingent on initial conditions and the maximum allowable steady-state tracking precision can only be guaranteed at some unknown(theoretically infinite)time,in this work the output of the system is ensured to synchronize with the desired trajectory with arbitrarily pre-assignable convergence rate and arbitrarily pre-specified precision within prescribed time,using output only with lower cost of sensing and communication.In addition,all the closed-loop signals are ensured to be globally uniformly bounded under the proposed control method.The merits of the designed control scheme are confirmed by numerical simulation on a ship model.

Asynchronous Learning-Based Output Feedback Sliding Mode Control for Semi-Markov Jump Systems: A Descriptor Approach

This paper presents an asynchronous output-feed-back control strategy of semi-Markovian systems via sliding mode-based learning technique.Compared with most literature results that require exact prior knowledge of system state and mode information,an asynchronous output-feedback sliding sur-face is adopted in the case of incompletely available state and non-synchronization phenomenon.The holonomic dynamics of the sliding mode are characterized by a descriptor system in which the switching surface is regarded as the fast subsystem and the system dynamics are viewed as the slow subsystem.Based upon the co-occurrence of two subsystems,the sufficient stochastic admissibility criterion of the holonomic dynamics is derived by utilizing the characteristics of cumulative distribution functions.Furthermore,a recursive learning controller is formulated to guarantee the reachability of the sliding manifold and realize the chattering reduction of the asynchronous switching and sliding motion.Finally,the proposed theoretical method is substantia-ted through two numerical simulations with the practical contin-uous stirred tank reactor and F-404 aircraft engine model,respectively.

Adaptive Optimal Output Regulation of Interconnected Singularly Perturbed Systems With Application to Power Systems

This article studies the adaptive optimal output regulation problem for a class of interconnected singularly perturbed systems(SPSs) with unknown dynamics based on reinforcement learning(RL).Taking into account the slow and fast characteristics among system states,the interconnected SPS is decomposed into the slow time-scale dynamics and the fast timescale dynamics through singular perturbation theory.For the fast time-scale dynamics with interconnections,we devise a decentralized optimal control strategy by selecting appropriate weight matrices in the cost function.For the slow time-scale dynamics with unknown system parameters,an off-policy RL algorithm with convergence guarantee is given to learn the optimal control strategy in terms of measurement data.By combining the slow and fast controllers,we establish the composite decentralized adaptive optimal output regulator,and rigorously analyze the stability and optimality of the closed-loop system.The proposed decomposition design not only bypasses the numerical stiffness but also alleviates the high-dimensionality.The efficacy of the proposed methodology is validated by a load-frequency control application of a two-area power system.

Event-triggered robust cooperative output regulation for a class of linear multi-agent systems with an unknown exosystem

This paper investigates the robust cooperative output regulation problem for a class of heterogeneousuncertain linear multi-agent systems with an unknown exosystem via event-triggered control (ETC). By utilizingthe internal model approach and the adaptive control technique, a distributed adaptive internal model isconstructed for each agent. Then, based on this internal model, a fully distributed ETC strategy composed ofa distributed event-triggered adaptive output feedback control law and a distributed dynamic event-triggeringmechanism is proposed, in which each agent updates its control input at its own triggering time instants. It isshown that under the proposed ETC strategy, the robust cooperative output regulation problem can be solvedwithout requiring either the global information associated with the communication topology or the bounds ofthe uncertain or unknown parameters in each agent and the exosystem. A numerical example is provided toillustrate the effectiveness of the proposed control strategy.

Observer Based Control for a Class of Systems with Output Deadzone Nonlinearity

In this paper, a combination of model based adaptive design along with adaptive linear output feedback controller is used to compensate for robotic manipulator with output deadzone nonlinearity. The deadzone dynamics are utilized to adaptively estimate the deadzone parameter and a switching function is designed to eliminate the error produced in the adaptive observer dynamics. The overall design of the closed loop system ensures stability in the BIBO criterion.

A 3D convolutional neural network model with multiple outputs for simultaneously estimating the reactive transport parameters of sandstone from its CT images

Porosity,tortuosity,specific surface area(SSA),and permeability are four key parameters of reactive transport modeling in sandstone,which are important for understanding solute transport and geochemical reaction pro-cesses in sandstone aquifers.These four parameters reflect the characteristics of pore structure of sandstone from different perspectives,and the traditional empirical formulas cannot make accurate predictions of them due to their complexity and heterogeneity.In this paper,eleven types of sandstone CT images were firstly segmented into numerous subsample images,the porosity,tortuosity,SSA,and permeability of the subsamples were calculated,and the dataset was established.The 3D convolutional neural network(CNN)models were subse-quently established and trained to predict the key reactive transport parameters based on subsample CT images of sandstones.The results demonstrated that the 3D CNN model with multiple outputs exhibited excellent prediction ability for the four parameters compared to the traditional empirical formulas.In particular,for the prediction of tortuosity and permeability,the 3D CNN model with multiple outputs even showed slightly better prediction ability than its single-output variant model.Additionally,it demonstrated good generalization per-formance on sandstone CT images not included in the training dataset.The study showed that the 3D CNN model with multiple outputs has the advantages of simplifying operation and saving computational resources,which has the prospect of popularization and application.

The Impact of The Three-Dimensional Cultivation Model on the Development of the Suzhou Tea Industry:Estimating Value of Output Per Acre and Diversified Sales Models

This article explores the impact of the three-dimensional cultivation mode on the development of the Suzhou tea industry,focusing on the diversified estimation of the value of output per acre and sales mode.It introduces the history and traditional cultivation practices of tea in Suzhou,as well as the current challenges and problems faced by the industry.An in-depth analysis was conducted on the overview and improvement plans of the three-dimensional cultivation mode,covering relevant technical methods.Based on this analysis,the impact of the three-dimensional cultivation on the value of output per acre was studied and predicted.Its potential and advantages were explored and compared with the effectiveness of traditional cultivation models.Additionally,the impact of the three-dimensional cultivation mode on sales was analyzed,examining its market adaptability and competitiveness,as well as its advantages in expanding sales channels and market coverage.The study also focused on the promoting effect of diversified sales models on the Suzhou tea industry,including direct consumption market development,tea processing product development and promotion,and the integration of tea culture and the tourism industry.To ensure sustainable development,the article evaluates the environmental impact,economic feasibility,social benefits,and farmer benefits of the three-dimensional cultivation model.Finally,the prospects for the development of the Suzhou tea industry were discussed,and the positioning and response strategies of the threedimensional cultivation model were proposed.

基于扰动和输入饱和限制的连续时间系统预见跟踪控制

本文研究一类带有外部干扰和输入饱和的连续时间系统的预见控制问题.为了能成功地构造出连续时间输入饱和系统的误差系统,与以往对系统方程求导不同,本文利用状态平移方法代替状态求导,使得输入饱和连续时间系统的误差系统的构造成为可能.这样原系统的预见饱和控制就转化为误差系统的标准饱和控制问题.另外,针对原系统的误差系统,分别引入状态反馈和静态输出反馈,并改写输入向量以便利用可预见信号的未来信息.利用Lyapunov函数及LMI技巧,导出了闭环系统渐近稳定的充分条件.最后仿真例子表明了本文结果的有效性.

基于半桥三电平LLC谐振变换器的混合控制策略研究

半桥三电平LLC谐振变换器具有体积小、开关器件少、开关器件耐压高等优势,已逐渐应用于直流充电模块后级为动力电池充电。针对传统变频调制(PFM)策略与移相调制(PSM)策略无法实现宽输出电压范围的问题进行分析,提出一种宽增益范围的移相-变频(PSM-PFM)混合控制策略。通过搭建一台功率为600 W、输出电压为20~60 V的实验样机进行验证。实验结果表明,所提控制策略相比单一调制策略具有更宽的增益,进而可实现宽输出电压范围,能够为动力电池提供稳定、宽范围且可调的充电电压,并实现开关管零电压开通。

基于感知与产出视角的维吾尔语辅音/n/的教学策略探析

本文主要以二语习得理论为基础,采用实验语音学的研究方法,以零基础开始学习的新疆大学维吾尔语专业不同水平(从低年级到高年级)学生为实验对象,进行感知和产出实验的研究。感知实验主要研究实验对象对目标辅音/n/的感知能力,结合知觉同化模型(PAM),分析偏误原因,探索维吾尔语辅音/n/的听力教学策略。产出实验主要通过第二共振峰频率跟舌位的关系,分析实验者在不同元音环境下发辅音/n/的舌位位置,结合有关口语的二语习得理论,探索维吾尔语辅音/n/的口语教学策略。

Pes/SV、P_(ET)CO_(2)在脓毒症休克患者容量负荷试验反应性判断中的应用

目的分析心室收缩末压与每搏量比值(Pes/SV)、呼气末二氧化碳分压(P_(ET)CO_(2))与脓毒症休克患者心排血量(CO)、平均动脉压(MAP)变化率的相关性及在脓毒症休克患者容量负荷试验反应性判断中的应用价值。方法选取2021年9月至2023年6月该院收治的128例脓毒症休克患者作为研究对象,所有患者均行容量负荷试验,根据容量负荷试验结果,将患者分为容量无反应组与容量有反应组。比较两组基线资料,以及扩容前后Pes/SV、P_(ET)CO_(2)、CO、MAP和扩容后CO、MAP变化率;采用Pearson相关分析扩容前Pes/SV、P_(ET)CO_(2)与扩容后CO、MAP变化率的相关性;采用多因素Logistic回归分析脓毒症休克患者容量反应性的影响因素;绘制受试者工作特征(ROC)曲线分析扩容前Pes/SV、P_(ET)CO_(2)单项及联合预测脓毒症休克患者容量反应性的价值。结果容量无反应组入院时急性生理学和慢性健康状况评价Ⅱ(APACHEⅡ)评分高于容量有反应组(P<0.05)。容量有反应组扩容后Pes/SV低于扩容前(P<0.05),扩容后P_(ET)CO_(2)、CO、MAP均高于扩容前(P<0.05);容量无反应组扩容后Pes/SV、P_(ET)CO_(2)、CO、MAP与扩容前比较,差异无统计学意义(P>0.05)。扩容前,两组Pes/SV、P_(ET)CO_(2)、CO比较,差异均有统计学意义(P<0.05);扩容后,两组Pes/SV、P_(ET)CO_(2)、CO比较,差异均无统计学意义(P>0.05)。容量有反应组扩容后CO、MAP变化率均高于容量无反应组(P<0.05)。相关性分析显示,扩容前Pes/SV与扩容后CO变化率、扩容后MAP变化率呈正相关(r=0.726、0.619,P<0.001);扩容前P_(ET)CO_(2)与扩容后CO变化率、扩容后MAP变化率呈负相关(r=-0.798、-0.759,P<0.001)。多因素Logistic回归分析结果显示:校正入院时APACHEⅡ评分后,扩容前P_(ET)CO_(2)升高是脓毒症休克患者容量无反应的危险因素(P<0.05),扩容前Pes/SV升高是脓毒症休克患者容量无反应的保护因素(P<0.05)。扩容前Pes/SV、P_(ET)CO_(2)单项及联合预测脓毒症休克患者容量无反应的AUC分别为0.786(95%CI:0.705~0.854)、0.751(95%CI:0.667~0.823)、0.930(95%CI:0.871~0.967),联合预测的AUC大于扩容前Pes/SV、P_(ET)CO_(2)单项预测的AUC(Z=4.129、4.303,P=0.026、0.022)。结论扩容前Pes/SV、P_(ET)CO_(2)与脓毒症休克患者扩容后CO、MAP变化率具有相关性,联合应用扩容前Pes/SV、P_(ET)CO_(2)能提高对脓毒症休克患者容量无反应的预测能力,可能为不能实施CO监测或潜在容量过负荷的患者提供了一种简单可行、实用、无创、准确度高的选择。

大型变压器高压间接出线区域油中气体扩散特性研究

大型变压器间接式升高座或出线盒作为绕组出线的关键通道,具有引线电流大、电场高且绝缘结构复杂等特点。同时该部位油隙大、油循环差,故障特征气体扩散困难或迟滞,将导致故障气体难以被在线或离线油中溶解气体诊断装置及时检测到。本文通过试验获得大型变压器间接式升高座或模拟油箱等油流不畅区域内部故障特征气体迁移扩散规律,掌握死油区特征气体输运扩散机理,为油循环结构优化及故障在线监测等提供参考,对保障变压器安全运行具有重要的意义。

基于XGBoost多输出模型实现宫颈癌VMAT中直肠和膀胱的DVH预测

目的基于XGBoost算法构建多输出模型,预测宫颈癌容积旋转调强放疗中膀胱和直肠的剂量。方法选取于我院进行宫颈癌容积旋转调强放疗的120例患者为研究对象。随机抽取20例患者作为测试集,将剩余100例患者数据按照4∶1采取五折交叉验证方式构建XGBoost预测模型。将所有患者CT中膀胱和直肠结构的与靶区边界距离直方图信息和计划中的剂量跌落函数f(x)作为输入,提取膀胱和直肠微分剂量体积直方图,并将其以2 Gy为间隔离散为多个剂量端点(Dose Endpoints,DEs)作为输出,建立多输出模型。使用平均绝对误差(Mean Absolute Error,MAE)和均方根误差(Root Mean Square Error,RMSE)评估模型各个DEs预测值与临床实际值之间的差异。使用剂量体积百分比(V_(Rx))对比模型预测积分剂量体积直方图(Cumulative Dose Volume Histogram,cDVH)曲线与临床cDVH的差异。结果直肠剂量体积直方图(Dose Volume Histogram,DVH)曲线中所有DEs的MAE为0.0206,RMSE为0.0287;膀胱DVH曲线中所有DEs的MAE为0.0339,RMSE为0.0450。对比预测值与临床实际值的V_(Rx),约91.8%的膀胱预测值和实际值差异小于5%误差范围。直肠预测值与实际值差异小于5%误差范围占比为94.0%。进一步分析发现,膀胱体积<500 mL时,模型DVH预测表现较好;膀胱体积>500 mL时,模型DVH预测结果有待提高。直肠在各个体积范围内,其模型DVH预测均表现较好。结论基于XGBoost算法的多输出DVH预测模型可帮助临床医师和物理师快速评估直肠和膀胱的器官受量,且该模型无需高性能的图形处理器即可快速完成优化过程,为机器学习在放疗中的应用提供新思路。

Difference of Nitrogen Uptake and Use Efficiency in Conventional Indica Rice Cultivars with Different Nitrogen Use Efficiency for Grain Output

[Objective] The study aimed to confirm difference of nitrogen uptake and used efficiency with different nitrogen use efficiency for grain output (NUEg) types of indica rice.[Method] 88 and 122 conventional indica rice cultivars were solution-cultured in 2001 and 2002, respectively. Dry matter weight (including root system, culm and sheath, leaves, panicle), nitrogen content of different organs, yield and its components were measured. The tested rice cultivars were classified into 6 types (i.e. A, B, C, D, E and F, A was the lowest, and F was the highest) based on their NUEg level by the MinSSw method.[Result](1)Difference of NUEg of the cultivars used in this study were very large; (2) No significant difference of N content at heading stage was observed among different NUEg types of indica rice. In the cultivars with higher NUEg, however, N content in leaf, stem-sheath and entire rice plant were lower at mature stage. (3)Cultivars with higher NUEg were characterized with lower N uptake before heading and at mature stage; (4) Cultivars with higher NUEg were characterized with higher N use efficiency in biomass production and harvest index. [Conclusion] The cultivars with higher NUEg showed lower N uptake and N content, while nitrogen use efficiency was higher.

Sizing of Energy Storage Systems for Output Smoothing of Renewable Energy Systems

光伏、风力发电等可再生能源（renewable energysources，RESs）具有随机性、间歇性等特点。为了抑制RESs输出波动对电网的不利影响，提出了用于平滑RESs发电系统功率输出的储能系统（energy storage system，ESS）容量优化确定方法。利用离散傅里叶变换（discrete Fouriertransform，DFT）对RESs输出功率进行频谱分析，基于频谱分析结果，考虑ESS充放电效率、荷电状态（stateofcharge，soc）及RESs发电系统目标功率输出波动率的约束，确定所需ESS最小容量。采用美国华盛顿州实际观测风速数据及日本东北电力公司风电场接入电网20rnin有功功率波动规范（最大波动率为10％），在一风力发电系统中对该方法进行了验证。算例结果表明采用该方法能够以较小的容量将风机输出最大波动率由61．7％降到9．9％。

Research and Design of an On-Chip High Efficiency Dual-Output Charge Pump

To meet the demands for different supply voltage levels on SOC required by digital modules like CPU core and analog modules,a novel dual-output charge pump is proposed. The charge pump can output a step-up and a step-down voltage simultaneously with a high driving capability. The multiple gain pair technique was introduced to enhance its efficiency. The proposed co-use technology for capacitors and switch arrays reduced its cost. The charge pump was designed and fabricated in a TSMC 0.35μm mixed-signal CMOS process. A group of analytical equations were derived to model its static characteristics. A state-space model was derived to describe its small-signal dynamic behavior. Analytical predictions were verified by Spectre simulation and testing. The consistency of simulated results as well as test results with analytical predictions demonstrated the high precision of the derived analytical equations and the developed models.

控制方向未知的受限多智能体系统的预设时间模糊控制

综合考虑受控制方向未知、输入受限和状态时延影响的有领导者多智能体系统的编队控制问题,设计基于模糊逻辑系统的预设时间一致性控制策略.为了保证编队输出误差在预设时间内满足预定的约束范围要求,引入预设时间性能函数,构造Lyapunov-Krasovskii(L-K)泛函解决状态时延问题,将外界干扰和L-K泛函的导数中的部分项定义为未知非线性函数,并利用模糊逻辑系统对其进行估计,利用Nussbaum函数和均值定理分别处理控制方向未知和输入受限问题,基于以上设计,提出预设时间模糊控制策略,并通过Lyapunov稳定性理论,分析闭环系统的有界稳定性,数值对比仿真和两级化学反应器应用仿真说明控制方法的有效性.