A Symbolic-Numeric Approach for Parametrizing Ruled Surfaces

This paper presents symbolic algorithms to determine whether a given surface(implicitly or parametrically defined) is a rational ruled surface and find a proper parametrization of the ruled surface. However, in practical applications, one has to deal with numerical objects that are given approximately, probably because they proceed from an exact data that has been perturbed under some previous measuring process or manipulation. For these numerical objects, the authors adapt the symbolic algorithms presented by means of the use of numerical techniques. The authors develop numeric algorithms that allow to determine ruled surfaces "close" to an input(not necessarily ruled)surface, and the distance between the input and the output surface is computed.     

Minimum Hausdorff distance under rigid motions and comparison of protein structures

Hausdorff distance between two compact sets, defined as the maximum distance from a point of one set to another set, has many application in computer science. It is a good measure for the similarity of two sets. This paper proves that the shape distance between two compact sets in R ⁿ defined by minimum Hausdorff distance under rigid motions is a distance. The authors introduce similarity comparison problems in protein science, and propose that this measure may have good application to comparison of protein structure as well. For calculation of this distance, the authors give one dimensional formulas for problems (2, n), (3, 3), and (3, 4). These formulas can reduce time needed for solving these problems. The authors did some numerical experiments for (2, n). On these sets of data, this formula can reduce time needed to one fifteenth of the best algorithms known on average. As n increases, it would save more time.     

The complexity and on-line algorithm for automated storage and retrieval system with stacker cranes on one rail

This paper considers an on-line scheduling and routing problem concerning the automated storage and retrieval system from tobacco industry. In this problem, stacker cranes run on one common rail between two racks. Multiple input/output-points are located at the bottom of the racks. The stacker cranes transport bins between the input/output-points and cells on the racks to complete requests generated over time. Each request should be accomplished within its response time. The objective is to minimize the time by which all the generated requests are completed. Under a given physical layout, the authors study the complexity of the problem and design on-line algorithms for both one-stacker-crane model and two-stacker-crane model. The algorithms are validated by instances and numerical simulations.     

一种基于数据融合的机动目标跟踪预测算法

在机动目标的运动跟踪中,为了减小搜索区域,需要对下一时刻目标位置进行预测。本文以医疗康复领域中基于视频的运动分析为背景,针对二维平面中静止背景的运动目标提出一种基于数据融合的预测跟踪方法。首先采用多项式拟合算法和基于“当前”模型的改进卡尔曼滤波算法分莉对运动目标进行位置预铡,然后采用数据融合的方法得到最终的预测结果．最后用计算机仿真和实验对所提出的预测算法进行了验证,结果表明本文算法与多项式拟合和卡尔曼滤波算法相比,预测误差更小,跟踪精度更高。     

Radau IIA方法对比例延迟微分方程的渐近稳定性

研究Raudau IIA 方法用于求解比例延迟微分方程时的渐近稳定性。近年来比例延迟微分方程数值解的性质已被数位数学家所研究,他们使用的步长都是定步长,一般情况下将推导出较难分析的递推关系,在本文中出于理论和计算两方面的原因,我们研究强制变步长计算方案,这种解法得到不变阶差分方程。我们证明了Raudau IIA 方法是渐近稳定的。     

Synchronous Parallel Block Coordinate Descent Method for Nonsmooth Convex Function Minimization

This paper proposes a synchronous parallel block coordinate descent algorithm for minimizing a composite function, which consists of a smooth convex function plus a non-smooth but separable convex function. Due to the generalization of the proposed method, some existing synchronous parallel algorithms can be considered as special cases. To tackle high dimensional problems, the authors further develop a randomized variant, which randomly update some blocks of coordinates at each round of computation. Both proposed parallel algorithms are proven to have sub-linear convergence rate under rather mild assumptions. The numerical experiments on solving the large scale regularized logistic regression with 1 norm penalty show that the implementation is quite efficient. The authors conclude with explanation on the observed experimental results and discussion on the potential improvements.     

高质量保形三角网格简化算法

网格简化算法在多分辨率模型显示、三角网格模型重构、网络传输等领域应用广泛,但是目前的简化算法简化后的网格,经常会出现极大、极小、狭长的三角片,质量不高。在基于QEM(QuadricErrorMetric)简化方法的基础上,提出了在点对折叠代价中引入折叠点对关联形状因子、法向量的夹角因子、边长的非线性加权因子3种优化因子,并配合虚折叠回退操作,对简化过程中网格质量进行综合优化,并取得了较好的简化结果。     

一种基于特征光流检测的运动目标跟踪方法

图像序列的运动目标分割检测与跟踪是一个具有广泛应用的困难问题,特别当目标被遮挡丢失和/或大幅度机动时,算法要有很强的鲁棒性才能实现高精度的连续跟踪。通过特征角点提取、由粗到细层级匹配特征光流及其聚类分析算法实现运动目标分割,利用卡尔曼滤波估计对目标的多特征点构成的最小凸多边形描述子进行跟踪,具有抗遮挡丢失和抗机动功能,因此在跟踪过程中能够较好地保持或重新检测目标的最小凸多边形,使检测与跟踪算法鲁棒性强。对运动目标真实图像序列的实验结果充分证明了算法的优良性能。     

推广的多传感器数据融合算法

本文对工程实际中多传感器系统线性化后存在未知的系统误差，测量噪声具有指数衰减相关，且与状态噪声相关的问题，提出了推广的多传感器数据的分层融合算法和多传感器自适应数据融合算法，给出了计算流程图，可以对目标的状态进行实时估计，这两种算法对防空导弹体系制导雷达组网数据融合具有理论意义与实用价值。     

基于半边结构的点删除算法研究

点删除是一种三角形网格模型化简算法,这篇文章在研究现有的删除算法基础上,对其中存在的一些问题进行了改进。采用半边结构替代原有的数据结构,采用顶点重要度作为选择顶点的一个依据,引入顶点法向作为删除顶点的判断准则,并且对删除后的空洞采用了面扩张算法进行重绘。以人头三维模型为例,通过实验验证了算法的有效性。     

干扰条件下的双基地定位跟踪

针对电子干扰日趋恶化的形势，文中专门研究了干扰条件下双基地系统如何利用数据融合实现对运动目标的三维跟踪问题。根据电子干扰“无－弱－强”的变化规律。文中提出了一种最大限度地利用两站测量数据信息量的“分段跟踪技术”、不仅提高了无、弱干扰时的跟踪精度，而且为强干扰条件下应用ＳＯＰＬＡＴ技术保持对目标的跟踪创造了有利条件。文中从理论。实际两个角度出发，分别研究了两种测量模式接收站采用的跟踪算法，通过典型航迹的计算机仿真．对基于数据融合算法的分段跟踪技术在理想观测精度和实际情况下的跟踪精度做了分析比较。     

PARAMETER-UNIFORM FINITE DIFFERENCE SCHEME FOR A SYSTEM OF COUPLED SINGULARLY PERTURBED CONVECTION-DIFFUSION EQUATIONS

A coupled system of singularly perturbed convection-diffusion equations is considered. The leading term of each equation is multiplied by a small positive parameter, but these parameters may have different magnitudes. The solutions to the system have boundary layers that overlap and interact. The structure of these layers is analyzed, and this leads to the construction of a piecewise-uniform mesh that is a variant of the usual Shishkin mesh. On this mesh an upwind difference scheme is proved to be almost first-order accurate, uniformly in both small parameters. We present the results of numerical experiments to confirm our theoretical results.     

基于自适应网格的跳频信号参数估计

分析了现有跳频信号稀疏重构算法的基不匹配问题,导致离散字典的稀疏表示能力变差,严重影响稀疏重构算法的性能。针对这种情形,提出了基于自适应网格的变分贝叶斯稀疏重构算法。该方法通过对字典不断地加权聚类和缩放处理,实现字典的自我更新,使得参数网格更加精细化。仿真结果表明,该方法具有良好的抗噪性能和交叉项抑制能力,同时缓解了稀疏重构算法的基不匹配情形,时频聚焦性进一步提高,能够在较低信噪比条件下,获取较高时频分辨率的时频矩阵,可以更精确地完成后续跳时刻检测、跳周期及跳频率等参数估计。     

基于混合遗传算法的目标优化分配

根据防空作战目标分配的特点 ,在分析启发式方法和遗传算法基础上 ,将二者结合起来得到了求解目标优化分配问题的混合遗传算法 ,该算法具有全局收敛性.     

A Poisson-Gaussian model to price European options on the extremum of several risky assets within the HJM framework

<正> This paper generalizes European call options on the extremum of several risky assets ina Poisson-Gaussian model which allows both the risky assets and stochastic interest rates movingrandomly with jump risks.The stochastic interest rate is assumed to follow an extended multi-factorHJM model with jumps.The authors provide explicitly the closed-form solutions of these optionsthrough the change of numeraire technique and examine the effects of both jump risks and stochasticinterest rate on the option price with numerical experiment.The model can be seen as an extension ofStulz(1982),Johnson(1987)and Lindset(2006).     

Scheduling problems with rejection to minimize the maximum flow time

This paper considers the scheduling problem with rejection on m identical parallel machines to minimize the maximum flow time. The authors show that this problem is NP-hard even when there is a single machine and all jobs have two distinct release dates. Furthermore, the authors present a dynamic programming algorithm and two approximation algorithms to solve them.     

单天线SAR动目标的检测和聚焦

单天线SAR运动目标检测系统具有结构简单、算法容易实现等特点,它的运动目标检测性能的完善很有应用意义.首先建立了运动目标SAR回波模型,结合单天线SAR运动目标检测系统,提出了一种基于频域对称扰动的能够对具有方位向速度的运动目标检测的新方法,在详细分析运动目标散焦程度和方位向速度关系的基础上,给出了检测原理以及实现检测的方法.对检测到运动目标的距离门单元,提出了用基于图像域的偏移自聚焦算法估计动目标的调频率,进而完成运动目标在SAR图像上的聚焦成像.并用计算机仿真结果和实测数据验证了算法的有效性.     

An improved algorithm for constructing moving quadrics from moving planes

This paper proposes an improved algorithm to construct moving quadrics from moving planes that follow a tensor product surface with no base points, assuming that there are no moving planes of low degree following the surface. These moving quadrics provide an efficient method to implicitize the tensor product surface which outperforms a previous approach by the present authors.     

Analysis of G-Queue with Pseudo-Fault and Multiple Working Vacations

This paper presents a new model of discrete time Geo/Geo/1 repairable queueing system with pseudo-fault, negative customers and multiple working vacations. The authors assume that system service may be interrupted by breakdown or pseudo-fault, this system may become disabled only when it is in a regular busy period, and negative customers adopt two types of typical killing strategies. In this paper, the authors know that the evolution of the system can be described by a two-dimensional Markov chain, and the two-dimensional Markov chain satisfies the condition of quasi birth and death chains. Based on the method of matrix-geometric solution, the authors obtain distributions for the stationary queue length in RCH and RCE strategy, respectively. Moreover, the reliability of the system is analyzed and the number of customers and waiting time of a customer in the system in steady state are obtained. The authors analyze the impact of two killing strategies on the system comparatively.This paper studies the individually and socially optimal behaviors of positive customers, and presents a pricing policy for positive customers, therefore, the authors obtain the socially optimal arrival rate.Various numerical results are provided to show the change of performance measures.     

基于互相关平动补偿的外辐射源成像技术

基于已有的无源雷达成像算法均未考虑目标的平动补偿问题,利用短时间内两次回波的强相关性,通过估计两次回波相关函数的最大值来估计补偿因子,进行平动补偿,然后利用直接FFT成像方法来对运动目标进行成像。仿真实验表明提出的互相关平动补偿算法在考虑了目标实际运动情况下,可以获得良好的成像质量。