Suppression of Chaotic Behaviors in a Complex Biological System by Disturbance Observer-based Derivative-Integral Terminal Sliding Mode

Coronary artery systems are a kind of complex biological systems. Their chaotic phenomena can lead to serious health problems and illness development. From the perspective of engineering, this paper investigates the chaos suppression problem. At first, nonlinear dynamics of coronary artery systems are presented. To suppress the chaotic phenomena, the method of derivative-integral terminal sliding mode control is adopted. Since coronary artery systems suffer from uncertainties, the technique of disturbance observer is taken into consideration. The stability of such a control system that integrates the derivative-integral terminal sliding mode controller and the disturbance observer is proven in the sense of Lyapunov. To verify the feasibility and effectiveness of the proposed strategy, simulation results are illustrated in comparison with a benchmark.

Parallel Control for Continuous-Time Linear Systems:A Case Study

In this paper,a new parallel controller is developed for continuous-time linear systems.The main contribution of the method is to establish a new parallel control law,where both state and control are considered as the input.The structure of the parallel control is provided,and the relationship between the parallel control and traditional feedback controls is presented.Considering the situations that the systems are controllable and incompletely controllable,the properties of the parallel control law are analyzed.The parallel controller design algorithms are given under the conditions that the systems are controllable and incompletely controllable.Finally,numerical simulations are carried out to demonstrate the effectiveness and applicability of the present method.Index Terms-Continuous-time linear systems,digital twin,parallel controller,parallel intelligence,parallel systems.

Distributed Adaptive Cooperative Tracking of Uncertain Nonlinear Fractional-order Multi-agent Systems

In this paper, the leader-following tracking problem of fractional-order multi-agent systems is addressed. The dynamics of each agent may be heterogeneous and has unknown nonlinearities. By assumptions that the interaction topology is undirected and connected and the unknown nonlinear uncertain dynamics can be parameterized by a neural network, an adaptive learning law is proposed to deal with unknown nonlinear dynamics, based on which a kind of cooperative tracking protocols are constructed. The feedback gain matrix is obtained to solve an algebraic Riccati equation. To construct the fully distributed cooperative tracking protocols, the adaptive law is also adopted to adjust the coupling weight. With the developed control laws,we can prove that all signals in the closed-loop systems are guaranteed to be uniformly ultimately bounded. Finally, a simple simulation example is provided to illustrate the established result.

Networked Control Systems:A Survey of Trends and Techniques

Networked control systems are spatially distributed systems in which the communication between sensors, actuators,and controllers occurs through a shared band-limited digital communication network. Several advantages of the network architectures include reduced system wiring, plug and play devices,increased system agility, and ease of system diagnosis and maintenance. Consequently, networked control is the current trend for industrial automation and has ever-increasing applications in a wide range of areas, such as smart grids, manufacturing systems,process control, automobiles, automated highway systems, and unmanned aerial vehicles. The modelling, analysis, and control of networked control systems have received considerable attention in the last two decades. The ‘control over networks’ is one of the key research directions for networked control systems. This paper aims at presenting a survey of trends and techniques in networked control systems from the perspective of ‘control over networks’, providing a snapshot of five control issues: sampled-data control, quantization control, networked control, event-triggered control, and security control. Some challenging issues are suggested to direct the future research.

Self-triggered Consensus Control for Linear Multi-agent Systems With Input Saturation

In this paper, we study the consensus problem for a class of linear multi-agent systems(MASs) with consideration of input saturation under the self-triggered mechanism. In the context of discrete-time systems, a self-triggered strategy is developed to determine the time interval between the adjacent triggers. The triggering condition is designed by using the current sampled consensus error. Furthermore, the consensus control protocol is designed by means of a state feedback approach. It is shown that the considered multi-agent systems can reach consensus with the presented algorithm. Some sufficient conditions are proposed in the form of linear matrix inequalities(LMIs) to show the positively invariant property of the domain of attraction(DOA). Moreover, some sufficient conditions of controller synthesis are provided to enlarge the volume of the DOA and obtain the control gain matrix. A numerical example is simulated to demonstrate the effectiveness of the theoretical analysis results.

Distributed H2/H∞ Filter Design for Discrete-Time Switched Systems

This paper addresses an infinite horizon distributed H2/H∞ filtering for discrete-time systems under conditions of bounded power and white stochastic signals. The filter algorithm is designed by computing a pair of gains namely the estimator and the coupling. Herein, we implement a filter to estimate unknown parameters such that the closed-loop multi-sensor accomplishes the desired performances of the proposed H2 and H∞ schemes over a finite horizon. A switched strategy is implemented to switch between the states once the operation conditions have changed due to disturbances. It is shown that the stability of the overall filtering-error system with H2/H∞ performance can be established if a piecewise-quadratic Lyapunov function is properly constructed. A simulation example is given to show the effectiveness of the proposed approach.

Novel Stability Criteria for Sampled-Data Systems With Variable Sampling Periods

This paper is concerned with a novel Lyapunovlike functional approach to the stability of sampled-data systems with variable sampling periods. The Lyapunov-like functional has four striking characters compared to usual ones. First, it is time-dependent. Second, it may be discontinuous. Third, not every term of it is required to be positive definite. Fourth, the Lyapunov functional includes not only the state and the sampled state but also the integral of the state. By using a recently reported inequality to estimate the derivative of this Lyapunov functional, a sampled-interval-dependent stability criterion with reduced conservatism is obtained. The stability criterion is further extended to sampled-data systems with polytopic uncertainties. Finally, three examples are given to illustrate the reduced conservatism of the stability criteria.

Multi-Variable Flocking Control for Multi-Agent Systems via a Received Signal Strength Indicator

A novel flocking control approach is proposed for multi-agent systems by integrating the variables of velocities, motion directions, and positions of agents. A received signal strength indicator （RSSI） is applied as a variable to estimate the inter-distance between agents. A key parameter that contains the local information of agents is defined, and a multi-variable controller is proposed based on the parameter. For the position control of agents, the RSSI is introduced to substitute the distance as a control variable in the systems. The advantages of RSSI include that the relative distance between every two agents can be adjusted through the communication quality under different environments, and it can shun the shortage of the limit of sensors. Simulation studies demonstrate the effectiveness of the proposed control approach.

Asynchronous Observer Design for Switched Linear Systems: A Tube-Based Approach

This paper proposes a tube-based method for the asynchronous observation problem of discrete-time switched linear systems in the presence of amplitude-bounded disturbances.Sufficient stability conditions of the nominal observer error system under mode-dependent persistent dwell-time(MPDT)switching are first established. Taking the disturbances into account, a novel asynchronous MPDT robust positive invariant(RPI) set and an asynchronous MPDT generalized RPI(GRPI)set are determined for the difference system between the nominal and disturbed observer error systems. Further, the global uniform asymptotical stability of the observer error system is established in the sense of converging to the asynchronous MPDT GRPI set, i.e., the cross section of the tube of the observer error system. Finally, the proposed results are validated on a space robot manipulator example.

Algorithms to Compute the Largest Invariant Set Contained in an Algebraic Set for Continuous-Time and Discrete-Time Nonlinear Systems

In this paper, some computational tools are proposed to determine the largest invariant set, with respect to either a continuous-time or a discrete-time system, that is contained in an algebraic set. In particular, it is shown that if the vector field governing the dynamics of the system is polynomial and the considered analytic set is a variety, then algorithms from algebraic geometry can be used to solve the considered problem. Examples of applications of the method(spanning from the characterization of the stability to the computation of the zero dynamics) are given all throughout the paper.

Sliding Mode Control of Coupled Tank Systems Using Conditional Integrators

For the problem of set point regulation of the liquid level in coupled tank systems, we present a continuous sliding mode control(SMC) with a "conditional integrator", which only provides integral action inside the boundary layer. For a special choice of the controller parameters, our design can be viewed as a PID controller with anti-windup and achieves robust regulation.The proposed controller recovers the transient response performance without control chattering. Both full-state feedback as well as output-feedback designs are presented in this work. Our output-feedback design uses a high-gain observer(HGO) which recovers the performance of a state-feedback design where plant parameters are assumed to be known. We consider both interacting as well as non-interacting tanks and analytical results for stability and transient performance are presented in both the cases. The proposed controller continuous SMC with conditional integrators(CSMCCI) provides superior results in terms of the performance measures as well as performance indices than ideal SMC, continuous SMC(CSMC) and continuous SMC with conventional integrator(CSMCI). Experimental results demonstrate good tracking performance in spite of unmodeled dynamics and disturbances.

Passivity and Passification of Uncertain Fuzzy Systems with Impulse

The passivity and feedback passification problems of fuzzy systems with parameter uncertainties and impulse are first presented in this paper. Based on the parallel distributed compensation （PDC） technique, some passivity and passification conditions are proposed in terms of linear matrix inequalities （LMIs）. Numerical examples are given to show the correctness and effectiveness of our theoretical results.

基于超效率DEA的地铁初近远期编组方案比选研究

编组方案是实现不同时期地铁运营模式与客流特征相匹配的基础,也是直接影响地铁规划建设成本和低碳运营的关键问题。在综合分析影响地铁编组方案关键要素的基础上,构建了地铁初近远期编组方案比选的综合评价指标体系,以及编组方案比选的两步筛选法;通过分析各指标对地铁编组方案影响的差异性,提出基于超效率DEA的地铁初近远期编组方案评价比选模型,并在对指标体系进行约简合并的基础上,从投入和产出两个角度对指标体系进行划分;最后,以实例验证和分析了地铁初近远期编组方案评价比选模型的可行性和合理性。算例分析结果表明:(1)固定编组方案属于成本赋能型方案,需较高的设备设施成本和运营投入;而更改编组方案属于技术赋能型方案,通过提高管理和技术水平,实现了运能匹配和乘客时间满意度等方面的有效产出;(2)更改编组方案和固定编组方案之间的优劣具有一定的动态性,需结合具体的线路条件、城市或企业财政情况、运营管理和技术水平等条件进行综合判断。本文提出的地铁初近远期编组方案比选理论方法适用于多种实践场景,具有一定的实用性,可为地铁初近远期编组方案比选的规范化提供一定的理论参考。

精神专科医院住院患者长期滞留风险评价指标体系的构建研究

目的:建立操作化的精神专科医院住院患者长期滞留风险评价指标体系。方法:依据文献研究、德尔菲法、AHP层次分析法,开展2轮专家函询,确定评价指标体系及各级指标权重,据此形成临床评估表,使用Pearson相关分析进行效度检验。结果:两轮函询,专家判断系数、熟悉系数、权威系数均值分别为0.8490、0.8800、0.8645,专家意见协调系数(W)分别为0.429、0.286,差异具有统计学意义(P<0.05)。运用层次分析法计算指标权重,经一致性检验(CR<0.1),得出一个包括3个一级指标(基础人口学特征、精神疾病病情、社会支持状况)、24个二级指标和76个三级指标的评价体系,各一级指标的权重分别为0.2232、0.183、0.5937。形成临床评估表,使用Pearson相关分析检验,样本(n=88)住院天数与长期滞留风险评分具显著相关性(r=0.695,P<0.01)。结论:综合文献研究、德尔菲法及AHP层次分析法,可筛选确定精神专科医院住院患者长期滞留的风险因素,由此形成的评估表具有良好效度与操作性,可为精神科开展临床路径,优化临床管理服务提供依据。

全身免疫炎症指数与急性主动脉夹层患者短期预后的关系

目的探讨全身免疫炎症指数(SII)与急性主动脉夹层(AAD)患者短期预后的关系。方法回顾性收集2019年6月至2022年5月上海长海医院急诊科收治的AAD患者249例,根据住院期间是否发生死亡分为预后良好组192例和死亡组57例。根据入院时SII将AAD患者分为四组(SII Q1~SII Q4),采用Kaplan-Meier曲线比较不同SII组的生存率;将单因素分析中有统计学意义的变量作为自变量进行Cox回归分析,探讨AAD患者短期预后的影响因素。结果本研究249例AAD患者,住院期间死亡57例,死亡率为22.89%。死亡组Stanford A型、累及分支血管、药物治疗比例、年龄、D-二聚体、SII、心肌肌钙蛋白T(cTnT)高于预后良好组,淋巴细胞计数低于预后良好组,差异有统计学意义(χ^(2)/t/U=20.359、6.935、31.633、6.459、4.427、3.998、2.597、2.130,P<0.05)。Log-rank检验显示,SII Q2组、SII Q3组、SII Q4组院内生存率分别为:79.7%、70.8%、66.1%,均低于SII Q1组(92.1%)(χ^(2)=4.262、10.501、14.021,P<0.05)。年龄、Stanford A型、D-二聚体、SII分层、手术治疗是AAD患者短期预后的影响因素(P<0.05)。结论死亡组AAD患者SII升高,为院内死亡的影响因素,临床应密切关注SII高的AAD患者。

饱和非线性光学介质中带折射率项的薛定谔方程的数值模拟

首先将带折射率项的非线性薛定谔方程转化成无限维哈密尔顿系统,证明了方程的质量和能量守恒特性;再利用傅里叶拟谱方法和平均向量场方法离散方程,对离散格式中非积分项采用Boole离散进行线积分近似,得到了离散方程的能量守恒数值格式,同时给出了方程的辛格式;然后以不同振幅的入射双曲正割型光脉冲为初值条件,模拟了保能量格式和辛格式在不同参数条件下光孤子的演化过程.最后分析了不同初始光脉冲和参数对光孤子传输的影响和保方程质量和能量守恒特性.

基于鱼类生物完整性的北京市山区河流生态健康评价

为了掌握北京市山区河流的生态健康状况,采用鱼类生物完整性指数(fish-index of biological integrity,F-IBI)进行了评价。于2021年8月、2022年5月、2022年10月对5条代表性山区河流的11个点位,进行了鱼类种群、水质、生境等调查。构建了鱼类生物完整性评价体系,确定核心指标9项,分别为鱼类总物种数(M1)、Shannon-Wiener多样性指数(M2)、鲤科鱼类占总物种数的百分比(M4)、鳅科鱼类占总物种数的百分比(M5)、底层鱼类百分比(M20)、杂食性鱼类数量百分比(M22)、耐受性鱼类数量百分比(M23)、黏性卵鱼类数量百分比(M26)和鱼类总个体数(M30)。采用比值法对上述核心指标进行赋分,并按照F-IBI得分将河流水生态健康状况划分为5个健康等级。结果显示研究区域河流生态健康状况良好,其中“优”、“良”点位占比为72.7%。通过分析F-IBI值与水质、生境等因素的相关性,发现全盐量、pH与F-IBI存在显著相关,而与水深、距闸坝的距离、溶解氧、透明度、化学需氧量、高锰酸盐指数、氨氮、总磷等不存在显著相关性。河道大量补充再生水会造成F-IBI下降,但是经过适当人工干预措施,如人工湿地,可以有效提升鱼类生物完整性。

四环素长期暴露对脱氮系统性能及微生物群落结构的影响

本实验通过构建序批式反应器(SBR),研究四环素浓度为0~35 mg/L的废水对硝化脱氮系统性能及微生物群落结构的影响。实验结果表明,四环素浓度≤20 mg/L时,硝化菌的活性随着暴露周期的增加而逐渐恢复。在四环素浓度为35 mg/L时,硝化菌失去活性,硝化系统崩溃。通过微生物群落结构分析可知,四环素的存在使Proteobacteria菌门产生一定的耐药性。随着四化素的浓度增加,对Ferribacterium和Nitrospira菌属的抑制程度越来越强,对Zoogloea和Pseudoxanthomonas菌属的抑制作用越来越弱。另外,四环素浓度为5 mg/L时利于Thauera菌属的生长。四环素浓度为35 mg/L时Nitrosomonas菌属全部失活。

A New Fire Detection Method Using a Multi-Expert System Based on Color Dispersion, Similarity and Centroid Motion in Indoor Environment

In this paper, a video fire detection method is proposed, which demonstrated good performance in indoor environment. Three main novel ideas have been introduced. Firstly, a flame color model in RGB and HIS color space is used to extract pre-detected regions instead of traditional motion differential method, as it’s more suitable for fire detection in indoor environment. Secondly, according to the flicker characteristic of the flame, similarity and two main values of centroid motion are proposed. At the same time, a simple but effective method for tracking the same regions in consecutive frames is established. Thirdly,a multi-expert system consisting of color component dispersion,similarity and centroid motion is established to identify flames.The proposed method has been tested on a very large dataset of fire videos acquired both in real indoor environment tests and from the Internet. The experimental results show that the proposed approach achieved a balance between the false positive rate and the false negative rate, and demonstrated a better performance in terms of overall accuracy and F standard with respect to other similar fire detection methods in indoor environment.

Quick System-Level DDR3 Signal Integrity Simulation Research

---Double data rate synchronous dynamic random access memory （DDR3） has become one of the most mainstream applications in current server and computer systems. In order to quickly set up a system-level signal integrity （SI） simulation flow for the DDR3 interface, two system-level SI simulation methodologies, which are board-level S-parameter extraction in the frequency-domain and system-level simulation assumptions in the time domain, are introduced in this paper. By comparing the flow of Speed2000 and PowerSI/Hspice, PowerSI is chosen for the printed circuit board （PCB） board-level S-parameter extraction, while Tektronix oscilloscope （TDS7404） is used for the DDR3 waveform measurement. The lab measurement shows good agreement between simulation and measurement. The study shows that the combination of PowerSI and Hspice is recommended for quick system-level DDR3 SI simulation.