Hierarchical Controller Synthesis Under Linear Temporal Logic Specifications Using Dynamic Quantization

Linear temporal logic(LTL)is an intuitive and expressive language to specify complex control tasks,and how to design an efficient control strategy for LTL specification is still a challenge.In this paper,we implement the dynamic quantization technique to propose a novel hierarchical control strategy for nonlinear control systems under LTL specifications.Based on the regions of interest involved in the LTL formula,an accepting path is derived first to provide a high-level solution for the controller synthesis problem.Second,we develop a dynamic quantization based approach to verify the realization of the accepting path.The realization verification results in the necessity of the controller design and a sequence of quantization regions for the controller design.Third,the techniques of dynamic quantization and abstraction-based control are combined together to establish the local-to-global control strategy.Both abstraction construction and controller design are local and dynamic,thereby resulting in the potential reduction of the computational complexity.Since each quantization region can be considered locally and individually,the proposed hierarchical mechanism is more efficient and can solve much larger problems than many existing methods.Finally,the proposed control strategy is illustrated via two examples from the path planning and tracking problems of mobile robots.

Application of Dynamic Linear Detecting Method in Data Processing of the Portable Blood Sugar Analyzer

In this paper,a dynamic linear detecting method,that the non-linear coefficient NL% was led and the non-linearity of data were estimated continuously and dynamically and determined when NL% exceeded reference value (5%),was used for data processing and could solve the problem caused by the phenomenon of substrate depleting occurred following the redox reaction in portable blood sugar analyzer.By contrast to the conventional end-point method,the dynamic linear detecting method is based on multipoint data collecting.Experiments of measuring the calibration glucose solution with 8 various concentrations from 50 mg/dl to 400 mg/dl were carried out with the analyzer developed by our group.The linear regression curve,whose correlation for the data was 0.9995 and the residual was 2.8080,were obtained.The obtained correlation,residual, and the computation workload are all fit for the portable blood sugar analyzer.

Dynamic inverse control of feedback linearization in ballistic correction based on nose cone swinging

It is a complicated nonlinear controlling problem to conduct a two-dimensional trajectory correction of rockets.By establishing the aerodynamic correction force mathematical model of rockets on nose cone swinging,the linear control is realized by the dynamic inverse nonlinear controlling theory and the three-time-scale separation method.The control ability and the simulation results are also tested and verified.The results show that the output responses of system track the expected curve well and the error is controlled in a given margin.The maximum correction is about±314 m in the lengthwise direction and±1 212 m in the crosswise direction from the moment of 5 s to the drop-point time when the angle of fire is 55°.Thus,based on the dynamic inverse control of feedback linearization,the trajectory correction capability of nose cone swinging can satisfy the requirements of two-dimensional ballistic correction,and the validity and effectiveness of the method are proved.

A Dynamic Active-Set Method for Linear Programming

An efficient active-set approach is presented for both nonnegative and general linear programming by adding varying numbers of constraints at each iteration. Computational experiments demonstrate that the proposed approach is significantly faster than previous active-set and standard linear programming algorithms.

SYNCHRONIZATION OF MASTER-SLAVE MARKOVIAN SWITCHING COMPLEX DYNAMICAL NETWORKS WITH TIME-VARYING DELAYS IN NONLINEAR FUNCTION VIA SLIDING MODE CONTROL

In this article, a synchronization problem for master-slave Markovian switching complex dynamical networks with time-varying delays in nonlinear function via sliding mode control is investigated. On the basis of the appropriate Lyapunov-Krasovskii functional, introducing some free weighting matrices, new synchronization criteria are derived in terms of linear matrix inequalities （LMIs）. Then, an integral sliding surface is designed to guarantee synchronization of master-slave Markovian switching complex dynamical networks, and the suitable controller is synthesized to ensure that the trajectory of the closed-loop error system can be driven onto the prescribed sliding mode surface. By using Dynkin＇s formula, we established the stochastic stablity of master-slave system. Finally, numerical example is provided to demonstrate the effectiveness of the obtained theoretical results.

A symplectic finite element method based on Galerkin discretization for solving linear systems

We propose a novel symplectic finite element method to solve the structural dynamic responses of linear elastic systems.For the dynamic responses of continuous medium structures,the traditional numerical algorithm is the dissipative algorithm and cannot maintain long-term energy conservation.Thus,a symplectic finite element method with energy conservation is constructed in this paper.A linear elastic system can be discretized into multiple elements,and a Hamiltonian system of each element can be constructed.The single element is discretized by the Galerkin method,and then the Hamiltonian system is constructed into the Birkhoffian system.Finally,all the elements are combined to obtain the vibration equation of the continuous system and solved by the symplectic difference scheme.Through the numerical experiments of the vibration response of the Bernoulli-Euler beam and composite plate,it is found that the vibration response solution and energy obtained with the algorithm are superior to those of the Runge-Kutta algorithm.The results show that the symplectic finite element method can keep energy conservation for a long time and has higher stability in solving the dynamic responses of linear elastic systems.

Application of scaled boundary finite element method in static and dynamic fracture problems

The scaled boundary finite element method （SBFEM） is a recently developed numerical method combining advantages of both finite element methods （FEM） and boundary element methods （BEM） and with its own special features as well. One of the most prominent advantages is its capability of calculating stress intensity factors （SIFs） directly from the stress solutions whose singularities at crack tips are analytically represented. This advantage is taken in this study to model static and dynamic fracture problems. For static problems, a remeshing algorithm as simple as used in the BEM is developed while retaining the generality and flexibility of the FEM. Fully-automatic modelling of the mixed-mode crack propagation is then realised by combining the remeshing algorithm with a propagation criterion. For dynamic fracture problems, a newly developed series-increasing solution to the SBFEM governing equations in the frequency domain is applied to calculate dynamic SIFs. Three plane problems are modelled. The numerical results show that the SBFEM can accurately predict static and dynamic SIFs, cracking paths and load-displacement curves, using only a fraction of degrees of freedom generally needed by the traditional finite element methods.

Spatio-temporal dynamics of vegetation in Jungar Banner of China during 2000–2017

It is known that the exploitation of opencast coal mines has seriously damaged the environments in the semi-arid areas.Vegetation status can reliably reflect the ecological degeneration and restoration in the opencast mining areas in the semi-arid areas.Long-time series MODIS NDVI data are widely used to simulate the vegetation cover to reflect the disturbance and restoration of local ecosystems.In this study, both qualitative(linear regression method and coefficient of variation(CoV)) and quantitative(spatial buffer analysis, and change amplitude and the rate of change in the average NDVI) analyses were conducted to analyze the spatio-temporal dynamics of vegetation during 2000–2017 in Jungar Banner of Inner Mongolia Autonomous Region, China, at the large(Jungar Banner and three mine groups) and small(three types of functional areas: opencast coal mining excavation areas, reclamation areas and natural areas) scales.The results show that the rates of change in the average NDVI in the reclamation areas(20%–60%) and opencast coal mining excavation areas(10%–20%) were considerably higher than that in the natural areas(<7%).The vegetation in the reclamation areas experienced a trend of increase(3–5 a after reclamation)-decrease(the sixth year of reclamation)-stability.The vegetation in Jungar Banner has a spatial heterogeneity under the influences of mining and reclamation activities.The ratio of vegetation improvement area to vegetation degradation area in the west, southwest and east mine groups during 2000–2017 was 8:1, 20:1 and 33:1, respectively.The regions with the high CoV of NDVI above 0.45 were mainly distributed around the opencast coal mining excavation areas, and the regions with the CoV of NDVI above 0.25 were mostly located in areas with low(28.8%) and medium-low(10.2%) vegetation cover.The average disturbance distances of mining activities on vegetation in the three mine groups(west, southwest and east) were 800, 800 and 1000 m, respectively.The greater the scale of mining, the farther the disturbance distances of mining activities on vegetation.We conclude that vegetation reclamation will certainly compensate for the negative impacts of opencast coal mining activities on vegetation.Sufficient attention should be paid to the proportional allocation of plant species(herbs and shrubs) in the reclamation areas, and the restored vegetation in these areas needs to be protected for more than 6 a.Then, as the repair time increased, the vegetation condition of the reclamation areas would exceed that of the natural areas.

Love Dynamical Models with Delay

A sufficient condition for the asymptotic stability of the equilibrium point of a system, which appears as a model for couple of the love affair with time delay, is obtained by applying the technique of linearized method and Hopf- bifurcation.

An efficient technique for recovering responses of parameterized structural dynamic problems

In this article,an effective technique is developed to efficiently obtain the output responses of parameterized structural dynamic problems.This technique is based on the conception of reduced basis method and the usage of linear interpolation principle.The original problem is projected onto the reduced basis space by linear interpolation projection,and subsequently an associated interpolation matrix is generated.To ensure the largest nonsingularity,the interpolation matrix needs to go through a timenode choosing process,which is developed by applying the angle of vector spaces.As a part of this technique,error estimation is recommended for achieving the computational error bound.To ensure the successful performance of this technique,the offline-online computational procedures are conducted in practical engineering.Two numerical examples demonstrate the accuracy and efficiency of the presented method.

高震区斜坡式护岸的岸坡稳定性分析

对位于菲律宾高震区的某斜坡式护岸结构的岸坡进行稳定性评估,分析国际上主流抗震设计规范,结合该工程的具体设计条件,提出合适的地震岸坡稳定分析方法、稳定标准和分析流程,并采用Newmark法和非线性动力分析对该护岸的震后残余位移进行计算。结果表明:高震区的岸坡稳定分析宜以控制位移为目标,水准1、2地震下的残余位移宜分别不超过5、30 cm;当采用Newmark法计算时宜取其上限位移,而通过非线性动力分析可获得岸坡残余位移和最大剪应变等的分布,从而对地震下的岸坡稳定做更为全面的设计和评估。

基于等效线性化的SISC隔震框架结构动力响应分析

为探究采用废旧轮胎隔震垫(STP)制成的柱下新型隔震装置(SISC)在村镇框架结构中的隔震效果,通过SAP2000建立隔震与非隔震三层框架结构模型,利用简化计算方法进行初步布置,采用反应谱法及时程分析法对比了隔震前后层间剪力比,并进行了上部结构的动力响应分析。结果表明:简化计算方法、振型分解反应谱法及时程分析法得到的底部剪力比分别为0.4207、0.4091、0.4491;隔震结构较非隔震结构自振周期延长2~3倍,由时程分析法可得隔震结构中上部结构层间位移角、顶层加速度较非隔震结构最大分别降低86.48%、49.26%,均满足规范限值要求,上部结构整体呈现平动;SISC隔震框架结构按照简化计算方法进行SISC初步布置具有可行性,该研究成果为STP隔震体系在村镇框架结构中的实际应用提供参考。

航天器气动耦合六自由度姿轨动力学多步法积分预报误差分析

航天器轨降过程中的姿态估计是载人航天领域中的重要一环.随着近些年测站精度的提高,任务要求的增加,且研究表明姿态会影响航天器轨降过程中受到的气动力,进而对轨道产生影响,因此发展高精度姿轨耦合预报对航天器状态实时测控至关重要.本文以“天宫一号”航天器轨降过程中姿轨耦合沿弹道联合预报为背景,研究线性多步法积分误差对大型航天器姿轨预报精度的影响.具体包括Adams-Bashforth法、Adams-Moulton法、预估校正法等,为大型航天器轨降过程中的姿轨耦合预报以及落点预报提供数据参考.

Collaborative optimization of linear vibrating screen screening efficiency and dynamic response stability based on coupled DEM-MBK simulation

The dynamic response stability of the vibrating screen is an important factor affecting the screening effect and the structural performance of the vibrating screen.In this paper,to improve dynamic response stability and screening efficiency,we optimized the configuration of linear screening process parameters based on the co-optimization method with dual objectives via the virtual experiment.Firstly,a coupled DEM-MBK simulation model was established according to the dynamics of linear screen,and the dy-namic response law of the screen machine under material impact was investigated.Secondly,the quantitative index of dynamic response stability according to the time-domain characteristics of the centroid amplitude was established.The trend and significance of three types of screening process pa-rameters,including excitation,damping and structure,on the screening efficiency and dynamic response stability were analyzed through virtual orthogonal experiments.Finally,a parameter configuration scheme to achieve co-optimization was proposed based on the comprehensive balance method.The virtual experiment results show that the screening efficiency and dynamic response stability of the proposed scheme are improved by 3.28%and 49.07%,respectively,compared with the empirical parameter configuration.Obviously,the co-optimization method can maintain high screening efficiency and dynamic response stability at the same time,which is beneficial to improve the service life of the screen surface and screen body.

分段线性系统经典数学模型的修正与动力学分析

由于间隙的存在,很多机械系统可以简化为分段线性模型,而简化后的模型中副簧系统通常包含阻尼.在大多数文献建立的数学模型中,主、副系统的接触点与分离点固定在间隙处.文章研究发现,由于副簧系统中弹簧与阻尼的力学特性不同,主、副系统的接触点与分离点位置实际上是随着系统参数和运动状态而变化的.若忽视这一点,后续的包括分岔和混沌在内的动力学分析就会出现误差甚至错误.首先基于经典的数学模型,用数值方法揭示了在简谐激励下主系统未返回到间隙处就与副簧系统提前分离,证明了经典数学模型的不当之处.进一步研究发现主系统不仅会出现提前分离,还会出现接触滞后的现象.因此对系统的接触与分离条件提出了修正,得到了更合理的数学模型.研究发现修正后的接触点、分离点位置与修正前相差较大,修正后的幅频响应曲线与修正前存在一定差别;在复杂运动中,修正前后的运动性质也可能发生改变,证明了修正后的模型更加合理,更能反映工程实际.然后,采用平均法并对平均法的积分区间进行推广,求得了修正模型的幅频响应的解析解,并通过龙格库塔法验证了解析解的正确性.对解析解进行稳定性分析,得到了解析解的稳定性判别式.最后,探究了修正模型的副簧系统参数对主系统幅频响应的影响.

加工误差对静压气浮主轴静动态性能的影响

为了改善静压气浮主轴静动态性能,研究了非均匀分布变节流孔直径静压气浮主轴结构。基于有限差分和线性小扰动法分析节流孔直径和分布不均匀性对主轴承载能力的影响,研究了轴套存在周向或轴向加工误差(正弦波纹、矩形波纹和三角波纹)对主轴静动态性能的影响。结果表明:节流孔直径系数为0.9~0.95时,承载能力提升最明显;周向或轴向加工误差有助于提高主轴承载能力;矩形和三角形波纹提高新型主轴承载能力更显著;轴向矩形波纹、三角波纹更有助于提高主轴稳定性;随着加工误差幅值增大,主轴稳定性降低。

在线优化参数的神经网络预测监督控制

使用具有辅助变量的全格式动态线性化方法逼近系统,构建了神经网络监督控制预测模型。利用线性跟踪-微分器建立过渡过程,应用线性扩张状态观测器估计输出预测值及其微分,给出了线性PID控制算法。根据对角回归神经网络构成直接逆控制,提出了改进的控制目标函数。依据非线性递推最小二乘法在线优化了PID控制参数和对角回归神经网络的连接权。当系统控制误差大于一定值时,重置PID控制参数。最后提出了在线优化参数的神经网络预测监督控制,克服了已有的神经网络监督控制存在建模难的问题。仿真研究结果表明控制算法的响应具有理想性能。

基于多目标优化模型的扇叶最优分组与排列方案

衡量某种机械单片扇叶结构优劣的指标有“质量”与“转动频率”两种参数,为了合理地装配整个风扇,需要相邻组的扇叶质量差达到最小,同时相邻叶片的频率差达到最大。首先构建一个单目标优化的质量分组模型,其后引入递推型动态规划算法,使得相邻组的扇叶质量差达到最小。同时考虑转动频率的影响,再建立一个多目标优化的质量分组模型,采用动态权重线性加权法,通过对比不同权重下相邻扇叶组的最大质量差和相邻扇叶的最大频率差,发现当A目标和B目标的权重均为0.5时,该模型所给出的方案效果最佳。

ON THE SOLVABILITY OF GENERAL LINEAR METHODS FOR DISSIPATIVE DYNAMICAL SYSTEMS

The main purpose of the present paper is to examine the existence and local uniqueness of solutions of the implicit equations arising in the application of a weakly algebraically stable general linear methods to dissipative dynamical systems, and to extend the existing relevant results of Runge-Kutta methods by Humphries and Stuart(1994). [ABSTRACT FROM AUTHOR]

考虑土结相互作用下核电厂海域沉管隧道三维抗震分析

为研究核电厂海域安全级取水沉管隧道的动力响应规律,综合考虑结构-土体的相互作用、复杂土体参数的非线性、沉管内部动水的对流效应和脉冲效应,建立了复杂土质地基条件下沉管-土体三维精细化有限元模型,并运用UPFs二次开发在ANSYS中创建了等价线性单元及黏弹性人工边界,在此基础上开展了极限地震作用下的沉管隧道动力时程分析。计算结果表明:层间位移角符合规范;顶板和底板以受弯为主,其中顶板3的弯矩最大,底板2的剪力最大;三个竖墙以受压为主。其中,中隔墙轴力最大;沉管隧道各墙连接部位内力较大,受地震影响最大。应提高顶底板的抗弯能力及竖墙的抗压能力,适当加固各墙连接部位,同时反应位移法、线弹性动力时程分析法、等价线性分析法三种方法计算出的内力规律基本一致,且等价线性法结果较为合理,反应位移法内力值较为保守。