Topic analysis using a finite mixture model

Addressed here is the issue of ‘topic analysis’ which is used to determine a text’s topic structure, a representation indicating what topics are included in a text and how those topics change within the text. Topic analysis consists of two main tasks: topic identification and text segmentation. While topic analysis would be extremely useful in a variety of text processing applications, no previous study has so far sufficiently addressed it. A statistical learning approach to the issue is proposed in this paper. More specifically, topics here are represented by means of word clusters, and a finite mixture model, referred to as a stochastic topic model (STM), is employed to represent a word distribution within a text. In topic analysis, a given text is segmented by detecting significant differences between STMs, and topics are identified by means of estimation of STMs. Experimental results indicate that the proposed method significantly outperforms methods that combine existing techniques.     

加速度传感器动态有限元分析

本文对传感器进行了模态分析、谐响应和瞬态分析,通过模态分析得到传感器的前六阶固有频率和振型,谐响应分析和瞬态分析得到传感器的幅频特性．得出传感器动态维间耦合情况,为后续的研究提供一定的参考。     

Fast finite time stability of stochastic nonlinear systems

This paper focus on fast finite time stability for a class of stochastic nonlinear systems. Firstly, a useful inequality, which will play a crucial role in the fast finite time stability in probability, is expanded on Bihari inequality. Then, the concept of fast finite time stability is discussed for stochastic nonlinear systems and an important theory concerned with fast finite time stability in probability is obtained. Next, a fast finite time state feedback controller can be subtle designed, which not only shortens the convergent time but also requires no large control effort. Three simulation examples are given to support our results of theoretical analysis.     

Cyclic codes over some finite quaternion integer rings

In this paper, cyclic codes are studied over some finite quaternion integer rings with respect to the quaternion Mannheim distance.     

The stochastic harmonic oscillator with finite correlation times

The moments of an undamped stochastic harmonic oscillator are examined using iteration procedures described in earlier papers. The noise is similar to white noise, but has finite correlation time which is taken to be less than the period of the oscillator. When the time of observation is finite, the first moment is explicitly given, attempting first-order approximation. For infinite time, we establish certain conditions which assure boundedness of the first and second moments. All the results obtained are applied to the white noise when its correlation time is considered finite.     

Matrix approach to verification of finite multi-potential games

This paper studies the verification of multi-potential games with a given partition, and proposes a kind of multi-potential equation based on semi-tensor product of matrices. Firstly, the basis of each player’s potential function is constructed, based on which, a new formula is established for the calculation of each player’s potential function. Secondly, a new potential equation is proposed for the verification of potential games via each player’s potential function. Using the new potential equation, a kind of multi-potential equation is constructed for the verification of multi-potential games with a given partition. It is proved that a finite game is a multi-potential game with a given partition if and only if the multi-potential equation has solution. In addition, all possible potential functions are obtained for each group of the partition. An illustrative example is worked out to show the effectiveness of the obtained new results.     

Dependency parsing with finite state transducers and compression rules

This article proposes a syntactic parsing strategy based on a dependency grammar containing formal rules and a compression technique that reduces the complexity of those rules. Compression parsing is mainly driven by the ‘single-head’ constraint of Dependency Grammar, and can be seen as an alternative method to the well-known constructive strategy. The compression algorithm simplifies the input sentence by progressively removing from it the dependent tokens as soon as binary syntactic dependencies are recognized. This strategy is thus similar to that used in deterministic dependency parsing. A compression parser was implemented and released under General Public License, as well as a cross-lingual grammar with Universal Dependencies, containing only broad-coverage rules applied to Romance languages. The system is an almost delexicalized parser which does not need training data to analyze Romance languages. The rule-based cross-lingual parser was submitted to CoNLL 2017 Shared Task: Multilingual Parsing from Raw Text to Universal Dependencies. The performance of our system was compared to the other supervised systems participating in the competition, paying special attention to the parsing of different treebanks of the same language. We also trained a supervised delexicalized parser for Romance languages in order to compare it to our rule-based system. The results show that the performance of our cross-lingual method does not change across related languages and across different treebanks, while most supervised methods turn out to be very dependent on the text domain used to train the system.     

基于ANSYS的热电冷却器有限元分析

主要介绍利用ANSYS的热电耦合分析功能,对热电冷却器的温度分布、电势分布进行模拟分析,为设计提供理论参考数据,使热电冷却器外形尺寸更加合理,降低试验造成的浪费,减少设计成本。     

A least squares finite element method applied to b-splines

In this article we construct a class of functions on a bounded irregular region Ω?R² which are of compact support, smooth and locally polynomials. The basic tool is the use of ordinary B-splines associated with the square containing Ω. This construction is then used for approximating the solution of Poisson's boundary value problem. The approximation is carried out through a least squares finite element method applied to the above class. Aside from some computational experiments, the objective is to emphasize the ease of generating the basis elements and the role of Kernel function in a convergence proof.     

A finite element based collocation method for eigenvalue calculations

The Method of Weighted Residuals (MWR) is a powerful tool in solving boundary value problems. A particular MWR is the “collocation method”. The main theme of this paper is eigenvalue calculations with the collocation method. The bench mark problems considered are second and fourth order differential operators in one dimension and a Helmholtz eigenvalue problem in two dimensions.     

Design and some applications of extended bandwidth finite gain amplifiers

A general theory is developed for extended bandwidth operation of actively compensated finite gain amplifiers. Designs for three new circuits are given which implement the theory. These circuits employ only operational amplifiers and resistors and their gains depend only on their resistor ratios. Thus they are suitable for IC fabrication. Further in IC technology, the characteristics of the operational amplifiers as well as the resistor ratios track closely with each other with reference to temperature and aging. Thus the extended bandwidth operation of the amplifiers will be available over a wide temperature range as well as under varying aging conditions. Their characteristics can be tuned easily by trimming only two resistors. Applications of the new amplifiers have been considered in RC active filters as well as in inductance simulation schemes. Experimental results are given which closely agree with theoretical predictions. The results also indicate that substantial improvement in the usable bandwidth of the circuits employing the new amplifiers may be expected over those using the conventional design of finite gain amplifiers.     

基于有限能力的离散型制造企业生产排程模型

ERP中基于无限产能的倒序排产方法已不能适应现代企业的管理需求,针对ERP生产排程方法的局限性,以离散型制造企业为研究对象,采用规划建模的方法,构建了一种基于有限能力的生产排程模型,给出了求解方法,并通过实例验证了模型的可行性与有效性。该模型可在满足设备负荷的情况下自动给出优化的排产方案,无需人工反馈和调整,能显著提高生产排程的使用效果。     

Global finite time stabilization of pure-feedback systems with input dead-zone nonlinearity

This paper is concerned with finite-time stabilization of a class of pure-feedback systems with dead-zone input. A systematic design procedure is established to derive the finite-time controller. Firstly, to circumvent the difficulties arising from the nonaffine properties, through a change of coordinates and incorporating mean value theorem, a system transformation technique is introduced to convert the original nonaffine system into an affine one. Then, based on the strengthened finite-time Lyapunov stability theorem as well as utilizing the bounds of dead-zone parameters, the finite-time stabilizer is explicitly constructed via backstepping design approach. It is proven that the designed controller can ensure all the states of the closed-loop system converge to zero in a finite time and maintain at zero afterwards. The proposed design framework is also extended to finite-time stabilization of uncertain pure-feedback systems and finite-time tracking control of pure-feedback systems. The effectiveness of the theoretical results are finally demonstrated by a numerical example and a realistic example.     

基于带内花键十字轴有限元分析及其应用

本文介带内花键结构的十字轴差速器的原理及其十字轴受力情况,运用NX 8.5建立三维模型并进行有限元分析,根据分析结果提出优化后模型,重新分析优化后结果。     

Least squares finite element approximation of Navier's equation

In this paper we construct a collection of vector functions which are later used as a basis in finding a least squares finite element approximation to Navier's equation. Through ideas from potential theory, pointwise convergence is demonstrated.     

MINRES法和有限元法解奇摄动反应扩散方程

讨论奇摄动反应扩散方程 的数值逼近求解问题, 及 均为正实数. 利用有限元方法并结合最小残量法, 给出求解该问题的一个新方 法, 该方法修正了单纯采用有限元方法求解时在边界附近呈现出的非正常扰动的 现象, 避免了因为 过小所引起的解的变异, 从而得到更加精确的数值结果.     

平面应变有限元法在基坑支护中的应用分析

本文结合沿海某基坑工程,运用Plaxis有限元程序建模并计算,对桩的水平位移、坑底隆起量、应力、桩体及内支撑弯矩、桩体和土体接触面应力进行分析。经实践证明,平面应变有限元法在该基坑支护设计中切实可用,可为类似工程的设计及施工提供一定的参考。     

Closed plane curves described by finite and infinite sums of rotating vectors

A large group of closed plane curves may be classified as roulettes, including epicycloids, hypocycloids, and related epitrochoids and hypotrochoids. The equation for the roulette in complex polar form shows that any roulette may be described by the vector sum of two vectors of specified constant magnitudes rotating with constant angular velocities. Methods for plotting, and for electronic display of roulettes are described. An equation is derived for a roulette approximation for an N-sided regular polygon. In particular, an application to two-dimensional potential theory is described and illustrated by consideration of the roulette approximation for a square as an equipotential curve, with derivation of equations for equipotential curves in the field surrounding the square. General equations are derived for given closed plane curves with points whose x and y coordinates may separately be expanded in Fourier series as functions of the polar angle, assuming these expansions are valid. It is shown that, in general, a closed plane curve may be considered as being described by an infinite sum of vectors, each rotating in a circle. Simplifying effects of symmetry about a polar axis and/or about the origin are discussed, and methods for harmonic analysis of a given closed plane curve with aid of an electronic calculator are described.