一种新的红外图像快速分割方法研究

研究红外图像目标分割快速优化问题。在高分辨率红外图像的分割中,红外图像存在数据量大、目标的边缘模糊和噪声较大等导致分辨率低和实时性差。为了快速准确分割,提出基于低尺度分割阈值预测的快速红外图像分割方法(LFIRS)。首先建立尺度阶数计算模型以确定保留原始红外图像目标基本信息所需的最小尺度,在分析多尺度过程对具有目标/背景强相关特性的红外图像进行分割阈值,建立多尺度红外图像分割阈值的相关模型(CLM),结合经典二维阈值法得到的最低两个尺度的阈值CLM模型参数,可以通过CLM模型与最小尺度的快速获取原始尺度的分割阈值,实现红外图像的快速分割。实验结果表明,改进方法提高了图像分辨和分割速度,且改善了分割效果。     

失速型风力发电机的建模与仿真研究

研究风力发电机系统优化控制问题,对风力发电进行设计,应通过风能带动发电机发电。但风力发电机组模型存在高阶、非线性问题,考虑因素很多。传统方法缺乏总体性能分析。为解决上述问题,建立了包括风力发电机组气动性能、传动系统部分和感应电机部分的一种新的较完善的失速型风力发电机组的动态数学模型。应用在MATLAB软件上,以数学模型为基础搭建了失速型风力发电机组数字仿真模型。并以稳态风速和动态风速为例,对600千瓦失速控制型风力发电机组进行了仿真计算。试验结果表明模型的正确性,为风力发电机组的进一步优化设计和优化控制等均提供了科学依据。     

基于复杂网络理论的高校内部理工医文合作研究分析

运用复杂网络理论的基本原理和有关方法,对理工医文等学科、专业之间的合作规律和人员合作方式进行探讨,以某高校2005-2010年医工合作情况作为实例展开研究,采用5年的合作数据作了计算分析,研究了高校内部理工医文开展学科交叉工作的特点及其运行情况、医工交叉合作中存在问题,客观分析其原因,提出了解决的办法,为今后开展高校系统的理工医文交叉合作,建设电子化交叉平台.     

信息融合技术在变压器油气识别故障诊断中的研究

变压器故障分为放电性故障和过热性故障两大类别,它们均会在变压器油中有所反映。本文通过对变压器油中主要气体的分析,判断变压器的故障类型。具体方法是:利用改进算法的BP网络和信息融合技术,以变压器油中五种主要特征气体作为神经网络的输入,以六种变压器状态作为相应的输出,通过加入动量因子,可以提高学习率系数,充分发挥改进算法的BP网络具有自适应学习能力的优势。仿真测试结果表明,本方法能够在较大范围内准确有效地进行变压器的故障诊断。     

基于最大加权独立集的频谱分配算法

动态频谱接入技术允许认知用户接入未授权的频谱,可以有效地提高频谱资源的利用率。频谱分配算法的时间开销和公平性是算法优劣的主要评价标准。本文从图论着色模型出发,构建了着色算法的评价体系及优化目标。针对用户间的公平性与分配的时间开销问题,在极大独立集的基础上提出了基于加权最大独立集的着色算法,获得了接近于最优的用户公平性,且该算法的时间开销等于信道数,与认知用户的数目无关。仿真分析验证了算法的正确性。     

基于S7-300 PLC的运动定位系统设计

本文利用西门子组态软件WinCC及编程软件S7-300PLC实现了二维平面的快速准确定位。并对系统的平台构架、硬件选型、功能实现,实时监控做了具体的分析与设计。本系统实现了本地控制与远程监控,运行操作方式灵活可靠。自投入使用以来,各项功能正常,达到了设计要求。     

Group contributions to activity coefficients from the hard sphere expansion corresponding states theory

A new method has been developed for predicting liquid activity coefficients in ternary mixtures from group contributions. In this method, activity coefficients are obtained from the excess Gibbs free energy of mixing at constant temperature and pressure. In calculating this excess function, the constituent and mixture Gibbs free energies are each represented by an expansion about a pure reference fluid in powers of ratios of hard-sphere diameters and molecular attraction parameters. When the pure component differs from the reference by a single structural group, these ratios represent, respectively, the size contribution and the attraction contribution of this group to the thermodynamic property of the pure fluid. Contributions of intermolecular repulsion to the excess Gibbs free energy are calculated directly from hard-sphere equations of state for the mixture and pure components. The effect of polar contributions calculated by a Padé approximant is also examined. Results indicate that the method developed from the hard-sphere expansion corresponding-states theory is useful for predicting activity coefficients in ternary mixtures when unlike-pair interaction parameters are fitted to binary activity coefficient data. Furthermore, the method shows promise in providing a theoretical basis for applying group contributions to activity coefficients.Nomenclature A Residual Helmholtz free energy - C _p Constant-pressure heat capacity - H _vap Heat of vaporization - P ^s Saturated vapor pressure - R Gas constant - T Temperature - U ^HS Hard-sphere internal energy - V _c Critical volume - V ^L Liquid volume - x Dimensionless residual thermodynamic property - Z Compressibility factor - d Center-to-center distance between two touching molecules - k Boltzmann constant - n Moles - x Liquid mole fraction - y Vapor mole fraction - Volume expansivity - Liquid activity coefficient - Minimum molecular attraction potential - Isothermal compressibility - Permanent dipole moment - 3.14159... - Density - Fugacity coefficient Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Discrete logarithms inGF(p)

Several related algorithms are presented for computing logarithms in fieldsGF(p),p a prime. Heuristic arguments predict a running time of exp((1+o(1)) ) for the initial precomputation phase that is needed for eachp, and much shorter running times for computing individual logarithms once the precomputation is done. The running time of the precomputation is roughly the same as that of the fastest known algorithms for factoring integers of size aboutp. The algorithms use the well known basic scheme of obtaining linear equations for logarithms of small primes and then solving them to obtain a database to be used for the computation of individual logarithms. The novel ingredients are new ways of obtaining linear equations and new methods of solving these linear equations by adaptations of sparse matrix methods from numerical analysis to the case of finite rings. While some of the new logarithm algorithms are adaptations of known integer factorization algorithms, others are new and can be adapted to yield integer factorization algorithms.     

Aluminum. II. Derivation of C v0from C p and comparison to C v0 calculated from anharmonic models

The specific heat at constant pressure, C _p, of aluminum measured by Ditmars, Plint, and Shukla has been reduced to the volume V ₀ appropriate for 0 K employing the Murnaghan equation. The C _v0 thus obtained is compared with the theoretical C _v0 calculated in the harmonic and the lowest-order anharmonic approximation from three different pseudopotentials (Harrison, Ashcroft, and Dagens-Rasolt-Taylor) as well as a phenomenological Morse potential. The higher-order ( ⁴) anharmonic contributions are calculated from the same nearest-neighbor Morse potential as in the lowest-order anharmonic theory. The role of the vacancy and the higher-order anharmonic contributions to C _v0 has been examined and we conclude that the ⁴ contributions to C _v0 are much smaller than the vacancy contribution. After removal of the vacancy contribution, the reduced C _v0 is found to be in excellent agreement with the Ashcroft and Harrison pseudopotentials as well as the Morse potential including the ² and ⁴ contributions to C _v0.