Achieving balance between proximity and diversity in multi-objective evolutionary algorithm

Currently, an alternative framework using the hypervolume indicator to guide the search for elite solutions of a multi-objective problem is studied in the evolutionary multi-objective optimization community very actively, comparing to the traditional Pareto dominance based approach. In this paper, we present a dynamic neighborhood multi-objective evolutionary algorithm based on hypervolume indicator (DNMOEA/HI), which benefits from both Pareto dominance and hypervolume indicator based frameworks. DNMOEA/HI is featured by the employment of hypervolume indicator as a truncation operator to prune the exceeded population, while a well-designed density estimator (i.e., tree neighborhood density) is combined with the Pareto strength value to perform fitness assignment. Moreover, a novel algorithm is proposed to directly evaluate the hypervolume contribution of a single individual. The performance of DNMOEA/HI is verified on a comprehensive benchmark suite, in comparison with six other multi-objective evolutionary algorithms. Experimental results demonstrate the efficiency of our proposed algorithm. Solutions obtained by DNMOEA/HI well approach the Pareto optimal front and are evenly distributed over the front, simultaneously.     

Illumination invariant extraction for face recognition using neighboring wavelet coefficients

The features of a face can change drastically as the illumination changes. In contrast to pose position and expression, illumination changes present a much greater challenge to face recognition. In this paper, we propose a novel wavelet based approach that considers the correlation of neighboring wavelet coefficients to extract an illumination invariant. This invariant represents the key facial structure needed for face recognition. Our method has better edge preserving ability in low frequency illumination fields and better useful information saving ability in high frequency fields using wavelet based NeighShrink denoise techniques. This method proposes different process approaches for training images and testing images since these images always have different illuminations. More importantly, by having different processes, a simple processing algorithm with low time complexity can be applied to the testing image. This leads to an easy application to real face recognition systems. Experimental results on Yale face database B and CMU PIE Face Database show that excellent recognition rates can be achieved by the proposed method.     

CrackTree: Automatic crack detection from pavement images

Pavement cracks are important information for evaluating the road condition and conducting the necessary road maintenance. In this paper, we develop CrackTree, a fully-automatic method to detect cracks from pavement images. In practice, crack detection is a very challenging problem because of (1) low contrast between cracks and the surrounding pavement, (2) intensity inhomogeneity along the cracks, and (3) possible shadows with similar intensity to the cracks. To address these problems, the proposed method consists of three steps. First, we develop a geodesic shadow-removal algorithm to remove the pavement shadows while preserving the cracks. Second, we build a crack probability map using tensor voting, which enhances the connection of the crack fragments with good proximity and curve continuity. Finally, we sample a set of crack seeds from the crack probability map, represent these seeds by a graph model, derive minimum spanning trees from this graph, and conduct recursive tree-edge pruning to identify desirable cracks. We evaluate the proposed method on a collection of 206 real pavement images and the experimental results show that the proposed method achieves a better performance than several existing methods.     

Study of dynamic characteristics of resonators for MEMS resonant vibratory gyroscopes

Dynamic characteristics of resonators for MEMS resonant vibratory gyroscopes are studied in this paper. Firstly, a small parameter method is introduced to analyze the dynamic characteristic stability of the resonator. It is proved that geometrical parameters of the resonator have to be regulated to match corresponding stability analysis. In order to verify the rationality of the theoretical parameters design, static calibration experiment is built using a resonator sample. It is concluded from the calibrated result that the error between theory design and experiment is 0.03?%, which shows they have a good match, and the design of resonator is reasonable. Moreover, the method of small parameter perturbation is considered to analyze the input–output dynamic characteristic. Under some transformations, which make input angular velocity and output resonant frequency shift possess a good linear relationship. In order to verify the correctness of the theory analysis method, dynamic frequency output characteristic experiment is built using the resonant vibratory gyroscope sample. It is concluded from the dynamic measurement result that the correlation coefficient of output fitted curve is 99.95?%, the measured algorithm scale factor of the gyroscope sample is 0.2116, which prove theoretical analyzing approach is feasible.     

Wing crack model subjected to high hydraulic pressure and far field stresses and its numerical simulation

By considering the effect of hydraulic pressure filled in wing crack and the connected part of main crack on the stress intensity factor at wing crack tip, a new wing crack model exerted by hydraulic pressure and far field stresses was proposed. By introducing the equivalent crack length l _eq of wing crack, two terms make up the stress intensity factor K _I at wing crack tip: one is the component K _I⁽¹⁾ for a single isolated straight wing crack of length 2l subjected to hydraulic pressure in wing crack and far field stresses, and the other is the component K _I⁽²⁾ due to the effective shear stress induced by the presence of the equivalent main crack. The FEM model of wing crack propagation subjected to hydraulic pressure and far field stresses was also established according to different side pressure coefficients and hydraulic pressures in crack. The result shows that a good agreement is found between theoretical model of wing crack proposed and finite element method (FEM). In theory, an unstable crack propagation is shown if there is high hydraulic pressure and lateral tension. The wing crack model proposed can provide references for studying on hydraulic fracturing in rock masses.     

基于ASP.NET的旅游网站的设计与实现

本文通过对旅游行业现状进行分析提出了基于ASP.NET的开发思路,介绍了旅游网站的功能设计、数据库设计和具体模块的实现代码。旅游网站包括旅游信息浏览、预定线路和后台管理等功能,通过旅游网站,可以满足游客的个性化需求,提高旅游服务质量,增加效益。     

最短路问题在旅游线路优化中的应用

本文利用Floyd算法探究了最短路问题,经过Matlab实现后将其应用到旅游线路优化设计中。选取了甘肃及周边地区13个旅游景点,求得从任意景点出发到任意目的景点的最短路,以及途中必须给定两个景点的最短路问题。     

内燃机工作过程三维两相反应流数值模拟

针对内燃机缸内工作过程三维两相反应流动问题开发了一套数值模拟程序.对气相流动采用Euler方法求解,用有限体积法离散控制方程组,采用SIMPLEC算法求解压力速度耦合.而对液滴相采用离散液滴模型(DDM),通过Lagrange方法求解.对液滴追踪采用了一种快速的颗粒追踪方法,考虑了液滴相与气相的完全双相耦合情况,采用Spalding模型描述液滴蒸发,同时采用涡破碎(EBU)模型计算化学反应速率.对TBD620发动机工作过程进行了数值模拟,数值计算结果分别与理论值和实验值吻合良好,压力峰值处误差在2％以内,验证了程序的可行性,并通过不同网格模型证明了程序的网格独立性.     

项目划分对工程质量评定的影响分析

近年来,关于项目划分和质量评定工作,实际操作中仍存在一些问题,原因在于我们对规程规范没有充分理解,使项目划分不够准确,导致评定结果失真。笔者通过对现行的水利水电工程施工质量检验与评定规程和水利水电建设工程质量等级评定标准的系统学习,同时参考有关专家学者的文献资料,结合自己的工作实践,对项目划分和质量评定进行了研究分析,与读者共勉。