Integral Theorems Based on a New Gradient Operator Derived from Biomembranes (Part II): Applications

Introduction Yin et al.[1, 2] described a gradient operator ? derived from biomembranes with “the second gradient operator” defined on a curved surface. Yin[2] then used the second gradient operator to develop a set of integral theorems named “the second category of integral theorems” on curved surfaces, including the second divergence theorem, the second gradient theorem, the second curl theorem, and the second circulation theorem: d d ?2 dA C A? A = ?K∫∫ ∫ ∫∫i v si Li v A iv (1) …     

Snakes外力场的改进及其左心室MRI的精确分割

参数活动轮廓模型（Snakes）分割图像时有两个明显的缺陷：要求初始轮廓线位于图像特征附近，且对深度凹陷区域的分割也不理想。基于梯度向量流（GVF）Snakes较好地解决了传统Snakes的两个本质缺陷。但是，由于GVF Snakes内力的性质和GVF的光滑性，使得对曲率大的边缘点不能精确定位。该文通过采用各向异性方程对图像扩散平滑和边缘增强，改善计算势能力场和梯度向量力场指向边缘的精确度。两种力场的有机组合作为Snakes的外力场。这种新的力场Snakes具有GVF Snakes和势能力场Snakes的优点，对左心室核磁共振图像（MRI）进行分割能得到精确的边缘轮廓。     

用气温梯度进行折光改正的三角高程测量及应用

提出了一种计算气温梯度进行大气垂直折光改正的，以倾斜距离为基础的三角高程测量方法，并用于建筑物的沉降观测，给出了某一观测周期中各沉降标志的下沉量的计算公式，理论分析证明其具有原理简单，高差测定范围大，易操作等优点。     

高等数学教学中新概念的引进

就梯度概念，微分概念的引进展开讨论，旨在说明高等数学中引进新概念的优越性和必要性，从而使学生能更深划地理解高等数学的概念与说明，提高学生的学习兴趣。     

一种基于梯度的HMM参数重估方法

对于隐Markov模型（HMM），经典的参数重估方法是Eaum-Welch算法，该算法基于最大似然准则，具有快速收敛和保证似然度单调增的优点，但是对于其他的训练准则，则不存在这样的算法，由于目标函数的复杂性，在考虑采用梯度方法时，必须先解决如何求取梯度的问题，为此，提出一种求取梯度的实现方法，结果表明，使用该方法所取得的模型与用Baum-Welch算法所得的模型性能相当，而前者适用于基于各种准则的训练方法。     

Deterministic approaches for noncoherent communicationswith chaotic carriers

1.INTRODUCTION Since1990s,chaoticsignalshavebecomepromising carriersincommunications[1].Severalschemeshave beendevelopedsuchaschaoticmasking[2],chaotic modulation[3],chaosspreadingspectrumcommunica tion[4],chaosshiftkeying(CSK)[5].Theadvantages ofutilizingchaoticdynamicsinsuchschemesinclude thebroadband,apparentlystochastic,δ likeautocor relation,natureofthesignalandtheeasewithwhich chaoticdatamaybegenerated.Andtheseschemes exploiteitherthesynchronizationprinciplesforchaot icsignals(…     

梯温场中玻璃陶瓷定向析晶的过程及工艺

以析晶理论和热传导理论为基础，研究了梯温场中玻璃陶瓷定向析晶的过程和工艺，分析了梯温场主要工艺参数——温度梯度、析晶界面温度、热源升温速率、边界条件等对定向析晶的影响，研究结果对于制定定向析晶工艺，制备性能优良的定向析晶玻璃陶瓷有一定意义。     

一个修正的HS公式及其全局收敛性

给出修正的HS公式,并且将其应用到无约束优化中,得到一类新的共轭梯度（型）算法,新的公式不需要任何线搜索可以保持充分下降性.此外,证明了算法的全局收敛性.     

Alternative Theorems and Sufficient Conditions of Global Convergence for a Class of Feasible Direction Algorithms

In this paper,two alternative theorems which differ from Theorem 10.2.6 in [1] andTheorem 1 in [3] are presented for a class of feasible direction algorithms.On the basis of alternativetheorems,furthermore,two sufficient conditions of global convergence of this class of algorithms areobtained.     

Multi-channel blind deconvolution algorithm for multiple-input multiple-output DS/CDMA system

Direct sequence spread spectrum transmission can be realized at low SNR,and has low probability of detection.It is aly problem how to obtain the original users'signal in a non-cooperative context.In practicality,the DS/CDMA sources received are linear convolute mixing.A more complex multichannel blind deconvolution MBD algorithm is required to achieve better source separation.An improved MBD algorithm for separating linear convolved mixtures of signals in CDMA system is proposed.This algorithm is based on minimizing the average squared cross-output-channel-correlation.The mixture coefficients are totally unknown.while some knowledge about temporal model exists.Results show that the proposed algorithm Can bring about the exactness and low computational complexity.