Continuous attractors of a class of neural networks with a large number of neurons

A class of simplified background neural networks model with a large number of neurons is proposed. Continuous attractors of the simplified model are studied in this paper. It contains: (1) When the background inputs are set to zero and the excitatory connections are in Gaussian shape, continuous attractors of the new network are obtained under some condition. (2) When the background inputs are nonzero and the excitatory connections are still in Gaussian shape, continuous attractors are achieved under some appropriately selected condition. (3) Discussions and examples are used to illustrate the theories developed.     

一类非完整约束系统的镇定与能控性

考虑非完整约束系统的镇定与能控性问题. 文中首先证明了虽然一般地说这类系统不能由光滑反馈镇定, 但它的存在性依赖于初值. 当初值在一个零测集外时, 这种反馈镇定确实存在. 然后我们证明了这类系统在分段光滑控制下全局可控. 由于证明是构造性的, 它给出了相应的控制.     

自行火炮发射动力学仿真

用ADAMS软件的履带工具箱模块(ATV)，建立了某自行火炮的多体系统动力学模型。该模型由炮身、反后坐装置、摇架、炮塔、车体、悬挂系统和行驶系统组成，共202个刚体，1029个自由度。将内弹道计算的发射时的火药气体压力施加于炮身，就动力轮锁定和不锁定两种情形，进行发射过程的动力学仿真，给出了关健部位的载荷时间历程。该文结果可为自行火炮发射时的强度设计和校核提供参考。     

Analysis of systems of singular ordinary differential equations

Systems of ordinary differential equations with a small parameter at the derivative and specific features of the construction of their periodic solution are considered. Sufficient conditions of existence and uniqueness of the periodic solution are presented. An iterative procedure of construction of the steady-state solution of a system of differential equations with a small parameter at the derivative is proposed. This procedure is reduced to the solution of a system of nonlinear algebraic equations and does not involve the integration of the system of differential equations. Problems of numerical calculation of the solution are considered based on the procedure proposed. Some sources of its divergence are found, and the sufficient conditions of its convergence are obtained. The results of numerical experiments are presented and compared with theoretical ones. Translated from Kibemetika i Sistemnyi Analiz, No. 5, pp. 103–110, September–October, 1999.     

步态识别问题的特点及研究现状

步态识别作为一种较新的生物认证技术有其独特优势,在计算机视觉研究领域又是一个难题.本文首先分析了步态识别问题的这两个特点.其次,按一个模式识别系统所涉及的4个问题域：传感器的选择、预处理技术、表达方法、决策模型为索引去分析步态识别问题.在表达方法一节中将文献中所反映的研究方法从计算机视觉的角度分为基于模型和基于整体的两大类,并对每类方法进行了举例说明,指出了所举出的方法的优缺点和其提取步态模式中的结构成分信息和运动特征信息时所采用的方法.再次,对步态识别算法性能评价标准和可得到的数据库进行了分析说明.最后得出了目前步态识别问题研究中的几个薄弱点,指出进一步研究此问题的发展空间.     

一类前馈系统的鲁棒镇定

Two kinds of saturated controllers are designed for a class of feedforward systems and the closed-loop resulted is locally input-to-state stable and input-to-state stable, respectively. By the word "locally", it is meant that there are restrictions on the amplitude of inputs. At first, under the guidance of suitable energy functions, two kinds of saturated controllers are designed as locally input-to-state stabilizers for a class of perturbed linear systems, from which explicit gain estimations can be obtained for the subsequent design. Then under the conditions that two subsystems of the feedforward system are respectively of locally input-to-state stability and input-to-state stability, the small gain theory is used to determine saturated degrees for corresponding robust stabilizers. The stability proofs are given by using a new characterization of input-to-state stability that is based on the concept of ultimate boundedness. As an application, saturated controllers are designed for the partial dynamics of a certain inverted pendulum.     

Problems of Evolution of Rotations of a Rigid Body under the Action of Perturbing Moments

The rotatory motion of a nearly dynamically spherical rigidbody, which contains a viscoelastic element, is considered. This elementis simulated by a moving mass, connected by a spring and damper to thepoint, situated on one of a principal axis of inertia. The smallparameters caused by the proximity of moments of inertia and thepresence of moving mass are considered to be of the same order. Thespherical coordinates defining the position of the angular velocityvector are introduced. The system of differential equations is obtainedand investigated, the special cases of motion are considered. Theauthors investigate perturbed rotational motions of a rigid body,similar to the regular precession in the Lagrange case, under the actionof the moment that is slowly changing in time and the restoring momentdepending on the angle of nutation. In two problems it is assumed thatthe angular velocity of the body is large and its direction is close tothe axes of dynamic symmetry. In the first problem it is assumed thattwo projections of the vector of the perturbing moment onto principalaxes of inertia of the body are small as compared to the restoringmoment, while the third one is of the same order of the magnitude as themoment in question. In the second problem it is assumed that theperturbing moments are small as compared to the restoring one. Averagedsystems of equations of motion are obtained and investigated in thefirst and the second approximations. Examples are considered.     

Optimization of conical shells of Mises material

Conical shells made of a von Mises material are considered. The shells are subjected to unifromly distributed lateral loading and are simply supported at outer edges whereas inner edges are absolutely free. The shell wall is assumed to be of piece-wise constant thickness. Resorting to the lower bound theorem of limit analysis, optimal designs of shells are established under given weight (material volume of a shell) which corresponds to the maximum load carrying capacity. Received May 15, 2000     

针织物悬垂屈曲的数值模拟

开发虚拟服装试衣系统需模拟织物的悬垂和屈曲,而采用正交异性力学模型不适合织物。为此,笔者基于针织物的细观力学模型,用有限元方法模拟方形针织物片铺在圆桌面上的悬垂和屈曲,该细观模型描述了织物由于其细观针织结构而特有的力学性质。织物片用8结点壳单元离散,这种壳单元被特别设计,能描述织物片在悬垂中发生的大转动。对织物片的屈曲模态进行了分析,对其后屈曲变形进行了计算,最后进行了方形织物片的悬垂和屈曲实验。模拟的结果和实验的观测结果很一致。研究成果为虚拟服装试衣系统的开发奠定了基础。     

基于CPLD的某型导弹测角仪视频信号模拟

针对导弹检测系统的训练和计量,采用CPLD技术设计了某型导弹电视测角仪视频信号模拟系统;介绍了测角仪的视频显示方式和模拟信号产生原理,并给出了CPLD主要的内部逻辑电路和VHDL语言描述;将视频信号分解为同步信号、固定图像和可控实心圆,以行计数器和列计数器构成图像的时间基准,通过对行、列计数器的编码实现同步信号和固定图像,通过对可逆计数器及行、列计数器的运算实现可控实心圆,并对可逆计数器的数据进行编码构成变焦数据,最终精确地实现了测角仪视频信号及其变焦数据输出的模拟。     

Intelligent Choice of Machine Learning Methods for Predictive Maintenance of Intelligent Machines

Machines are serviced too often or only when they fail. This can result in high costs for maintenance and machine failure. The trend of Industry 4.0 and the networking of machines opens up new possibilities for maintenance. Intelligent machines provide data that can be used to predict the ideal time of maintenance. There are different approaches to create a forecast. Depending on the method used, appropriate conditions must be created to improve the forecast. In this paper, results are compiled to give a state of the art of predictive maintenance. First, the different types of maintenance and economic relationships are explained. Then factors for the forecast are explained. Requirements for the data are collected and algorithms for machine learning are presented. Based on the relationships found, a process model is presented that shows a fast implementation of the predictive maintenance for machines.     

On organization of markets of homogeneous goods

Different supply function auctions in a market of homogeneous good are considered. The problems of the unique existence and computation of a Nash equilibrium are studied for these models. Estimates of the Nash equilibrium deviation from the competitive equilibrium are obtained for each case. For a first-price auction different indexes of the “market power” are investigated as applied to the electricity market. It is shown that the ordinary criteria of competitive behavior are too gentle for this market. Stronger conditions are formulated that provide sufficiently small deviation of the market price from the competitive equilibrium price. The problem of optimal organization of an auction is discussed from the viewpoint of welfare maximization. The obtained results are applied to the analysis of the electricity market in Russia.     

Conversion of units of measurement

Algorithms are presented for converting units of measurement from a given form to a desired form. The algorithms are fast, are able to convert any combination of units to any equivalent combination, and perform dimensional analysis to ensure that the conversion is legitimate. Algorithms are also presented for simplification of symbolic combinations of units. Application of these techniques to perform automatic unit conversion and unit checking in a programming language is described     

石英谐振器的电路设计与力频特性的研究

根据共模抑制原理,基于一种单基多电极石英晶体谐振器的结构,设计了一种新型的信号处理电路,这种电路将同一晶体基片上不同位置的谐振器对应的谐振频率作混频处理,然后采用差频、求和,最后倍频输出的方式输出,描述了各部分电路的设计.在分析石英谐振器的能限理论及力一频特性的基础上,用此方案设计的电路进行AT切同基三电极石英谐振器的力一频特性实验,记录了不同加力方式下的力一频特性,结果显示这种电路优化了力一频系数,线性度良好.在一定的加力方式下,经求和电路处理后的力一频系数可达139.72 Hz/N.     

集群系统通信性能的测量

集群系统通信性能作为影响集群性能的主要因素之一,其测量对寻找集群内部通信瓶颈具有指导作用。采用NetPIPE基准测试对PC集群系统和Sun工作站集群的通信性能进行了测量,实验结果与理论分析一致,表明在通信性能方面,MPI环境整体上优于PVM,合并一些非相关短消息为长消息能够优化集群应用。并采用性能模拟的方法,以基准测试为工具,对两个集群系统的带参数LogP通信模型进行了定量化地测量和计算,完整表征了集群通信子系统的通信性能特征。     

Identification of finite dimensional models of infinite dimensional dynamical systems

The identification of finite dimensional discrete-time models of deterministic linear and nonlinear infinite dimensional systems from pointwise observations is investigated. The input and output observations are used to construct finite dimensional approximations of the solution and the forcing function which are expanded in terms of a finite element basis. An algorithm to determine a minimal basis to approximate the data is introduced. Subsequently, the resulting coordinate vectors are used to identify a finite dimensional discrete-time model. Theoretical results concerning the existence, stability and convergence of the finite dimensional representation are established. Numerical results involving identification of finite dimensional models for both linear and nonlinear infinite dimensional systems are presented.     

随机算法异步并行化的效率分析

随机算法的执行时间具有不确定性,这种不确定性为随机算法的异步并行提供了良好的基础,已有许多计算实验表明了随机算法的异步并行可以达到线性甚至超线性的加速.对于求解SAT问题的随机算法RDP,研究了异步并行效率与运行时间分布和处理器数目之间的关系.应用一种单峰分布──分段线性分布模型来模拟随机算法的运行时间分布.理论分析和计算结果均表明:当处理器数目k较小和单峰位于分布的前部时,随机算法的异步并行具有近线性加速.     

On the recognition of printed characters of any font and size

We describe the current state of a system that recognizes printed text of various fonts and sizes for the Roman alphabet. The system combines several techniques in order to improve the overall recognition rate. Thinning and shape extraction are performed directly on a graph of the run-length encoding of a binary image. The resulting strokes and other shapes are mapped, using a shape-clustering approach, into binary features which are then fed into a statistical Bayesian classifier. Large-scale trials have shown better than 97 percent top choice correct performance on mixtures of six dissimilar fonts, and over 99 percent on most single fonts, over a range of point sizes. Certain remaining confusion classes are disambiguated through contour analysis, and characters suspected of being merged are broken and reclassified. Finally, layout and linguistic context are applied. The results are illustrated by sample pages.     

Evaluation of Architectures for Mobile Robotics

In this paper we make a comparative study of some successful software architectures for mobile robot systems. The objective is to gather experience for the future design of a new robot architecture. Three architectures are studied more closely, Saphira, TeamBots and BERRA. Qualities such as portability, ease of use, software characteristics, programming and run-time efficiency are evaluated. In order to get a true hands-on evaluation, all the architectures are implemented on a common hardware robot platform. A simple reference application is made with each of these systems. All the steps necessary to achieve this are discussed and compared. Run-time data are also gathered. Conclusions regarding the results are made, and a sketch for a new architecture is made based on these results.     

一种新型神经网络结构模型的应用研究

基于过程先验知识与神经网络结构选择相结合的思想,提出了一类新型神经网络结构,并 具体研究了其学习算法.同时给出了一种新的样本抽取方法及其相应的网络训练步骤.这些 思想和方法均在复杂尿素生产过程的建模和优化中得到了应用.基于所建神经网络模型知识 的专家系统已在某化肥厂得到成功的应用.