退化时滞系统的极点配置

This paper deals with the pole placement of the singular system Ex~.=Ax(t) Dx(t-(?)) Bu, y=Cx, where x∈R~n,u∈R~m,and y∈R~n are its state,control input and measure output respectively;E,A∈R~(n×n),B∈R~(n×m),and C∈R~((?)×n) are constant matrices.It is also assumed that rankE相似文献   

基于磁光晶体的光纤电流传感器磁串扰效应研究

对光学电流传感器测量电流时存在的相邻导线磁串扰问题进行了研究,提出了一种利用传感头的摆放位置和角度来消除磁串扰对电流测量影响的方法.通过理论分析给出了磁串扰的大小与两导线间距以及传感头与主导线的距离和夹角之间的定量关系,从而确定测量条件下的传感头的最佳摆放方案,并以此为依据进行了相应的实验测量和分析,结果表明当传感头处于最佳摆放位置时较好的消除了相邻导线磁串扰的影响,提高了光学电流传感器的测量精度.     

混沌时滞神经网络系统的反同步

利用状态观测器方法研究了一类带时滞的混沌神经网络系统的反同步问题.与应用于其他混沌系统的反同步方法相比,提出的方法更为简便,并且利用极点配置技术,只要通过调整特征值来实现反同步速率的快慢.最后,给出了数值例子和计算机仿真结果来验证该方案的有效性. 关键词： 混沌神经网络 状态观测器 极点配置技术 反同步     

双参数曲面的泡泡网格化方法

为将双参数曲面离散成高质量的网格,首先在参数域内利用各向异性的非均匀泡泡布点方法优化布点,然后用各向异性Delaunay三角化方法将参数域网格化,最后用映射法得到双参数曲面的离散网格.参数域中的节点由二阶黎曼度量矩阵控制,该度量矩阵由三维曲面的网格度量矩阵和曲面参数方程的梯度计算得到.数值算例表明,泡泡布点法在参数域上能生成满足度量矩阵要求的节点集,将节点连接成网格并投影回曲面,所得曲面网格具有很高的质量.     

Significant Improvement of the Processability of Ladder‐Type Polymers by Using Aqueous Colloidal Dispersions

Summary: It has been shown that stable aqueous dispersions of nanoparticles of the rigid‐rod ladder‐type polymer poly(benzo‐bisimidazobenzo‐phenanthroline) (BBL) can be prepared in order to facilitate BBL processing. The obtained dispersions have a controllable particle size in the range between 50 and 150 nm and, consequently, the deposition of layers by spin‐coating or drop‐casting is realized. The resultant films exhibit a particulate structure and their morphology has been characterized by means of SEM and AFM. Upon investigation of the BBL dispersions in organic field‐effect transistors an ambipolar charge carrier transport has been observed, which presumably is related to the presence of mobile ions.

SEM image of a drop‐cast film of the BBL nanoparticles.     

Voice and airway restoration: Endoscopic placement of molds and stents

Severe damage to the vocal folds and upper airways after translaryngeal endotracheal intubation occurs with greater frequency and to a greater extent than is usually surmised. Videolaryngoscopic techniques have led to prompt recognition of endolaryngeal/endotracheal lesions in the critical care setting. Traditionally, surgeons have treated obstructive sequelae such as glottic, subglottic, and tracheal stenosis by major transcervical and/or transthoracic resective and reconstructive surgery. Endolaryngeal core molds and endotracheal stents have conventionally been inserted by open surgical techniques. As a prototypic case illustrates, evolutional methods of endoscopic placement of prosthetic molds and stents combined with endoscopic optical/suction instrumentation and laser photoresection allow the physician to restore upper airway patency and phonatory vocal fold function without resorting to major surgery. Delta scan topograms provide radiographic imaging of the major airways.     

On the Convergence of Inhomogeneous Markov Chains Approximating Equilibrium Placements of Flexible Objects

This paper deals with the minimization of local forces in two-dimensional placements of flexible objects within rigid boundaries. The objects are disks of the same size but, in general, of different materials. Potential applications include the design of new amorphous polymeric and related granular materials as well as the design of package cushioning systems. The problem is considered on a grid structure with a fixed step size w and for a fixed diameter of the discs, i.e., the number of placed disks may increase as the size of the placement region increases. The near-equilibrium configurations have to be calculated from uniformly distributed random initial placements. The final arrangements of disks must ensure that any particular object is deformed only within the limits of elasticity of the material. The main result concerns -approximations of the probability distribution on the set of equilibrium placements. Under a natural assumption about the configuration space, we prove that a run-time of n+log^O(1)(1/} is sufficient to approach with probability 1 – the minimum value of the objective function, where depends on the maximum of the escape depth of local minima within the underlying energy landscape. The result is derived from a careful analysis of the interaction among probabilities assigned to configurations from adjacent distance levels to minimum placements. The overall approach for estimating the convergence rate is relatively independent of the particular placement problem and can be applied to various optimization problems with similar properties of the associated landscape of the objective function.     

Inventory placement in acyclic supply chain networks

By adding a set of redundant constraints, and by iteratively refining the approximation, we show that a commercial solver is able to routinely solve moderate-size strategic safety stock placement problems to optimality. The speed-up arises because the solver automatically generates strong flow cover cuts using the redundant constraints.     

Load-aware femtocell placement in the commercial buildings

Femtocells are designed to cover small indoor areas. In commercial buildings, femtocell placement and number is one of the most important network issues. In such buildings, another problem is uneven traffic distribution in different spaces, which causes high traffic and low traffic areas. Due to the small coverage areas of femtocells and these high traffic and low traffic areas, some femtocells are overloaded and some femtocells are underloaded. Also, increase in the distance of high-traffic areas from the femtocells, increases the number of resource blocks used. These issues reduce network efficiency. In this article, femtocell placement has been managed in such a way that the traffic load on the femtocells is balanced and is reduced the number of resource blocks used in the building and efficiency is increased. A mathematical model for femtocell placement has been introduced which balancing the femtocell load and reducing the average number of resource blocks used, the conditions of maximum coverage area and minimum femtocell number should also be fulfilled. This challenge has been addressed by using non-dominated sorting genetic algorithm (NSGA-II). An initial population generation algorithm and a selection function are also presented. The assessment results indicate that compared to the latest studies, this newly proposed method reduces the average load on the whole building by 79% and decreases the load variance between the femtocells by 86%.     

高超音速飞行器鲁棒控制器设计

军事变革和信息化战场环境的变化,促使空天攻防作战成为未来作战的战场之一。临近空间高超音速飞机和导弹会对传统攻防体系带来颠覆性冲击。复杂环境对高超音速飞行器控制技术的发展提出了严峻的挑战,本文针对吸气式高超音速飞行器在飞行包线内动态特性易变、稳定性较差、不确定因素较多以及对外界扰动敏感以及整个执行机构控制能力弱和动态特性低等的控制问题,首次提出了一种能同时抑制扰动和模型不确定性的基于优化控制的鲁棒控制方法,保证飞行器能得到很好地控制,快速响应环境变化并很快回到稳定飞行的状态。采用线性矩阵不等式方法来设计飞行控制系统,给出了不确定系统稳定的条件, 将反馈稳定问题转化为了一个最优控制问题。同时将闭环极点在一定区域内参与优化,进一步提高优化效率。与文献方法仿真对比结果证实了本文方法的优越性。