First-principles prediction of ductility in β-type Ti-Mo binary alloys

Recent studies suggest that the ratio of the shear modulus (G) to the bulk modulus (B) and the Poisson’s ratio (ν) are good indicators of ductility. Using the method of supercell and the first-principles pseudopotential plane-wave method, the G/B and ν of the β-type Ti-Mo binary alloys with Mo molar fraction (x _Mo) ranging from 6.25% to 37.5% are calculated. The results show that the ductility of β-type Ti-Mo binary alloys first increases with increasing x _Mo and reaches the maximum when x _Mo is about 25%, and then reduces with more increasing x _Mo. The charge density difference calculations suggest that the x _Mo dependence of the ductility can be ascribed to the change of bonding characteristics between Ti and Mo atoms in the [111] direction.     

基于二维主分量分析的人耳身份识别研究

有效的特征提取方法是解决人耳身份识别任务的关键之一。以主分量分析（PCA）为代表的线性子空间方法在特征提取工作中得到了广泛应用。为了更有效地提取人耳图像特征并减少运算量,将基于二维图像矩阵的2D-PCA方法应用于人耳身份识别。针对三个USTB人耳图像库,采用最近邻分类器,研究了选用不同的特征维数、贡献率,及不同的相似性测度时,2D-PCA方法与传统的PCA方法的识别性能。交叉验证的实验结果表明：2D-PCA方法较PCA方法获得了更短的训练时间和更高的识别率,说明基于图像矩阵的2D—PCA方法是一种效率更高,鲁棒性更强的人耳身份识别方法。     

基于ASP.NET的专业气象服务系统的权限控制实现

使用ASP.NET提供的HttpModule技术,对用户提交的Http请求进行解析.辅以合理的权限数据库结构设计,实现了专业气象服务网站的权限分配和管理.在实际开发过程中,通过权限数据库来动态生成导航菜单及其级联菜单,使得用户的权限分配和管理变得更加灵活、高效.     

一种改进的IGBT稳态解析模型

根据IGBT物理结构与基区过剩载流子的分布特点进行半导体物理公式推导,参考现有模型并对其不足之处进行改进,把整个基区分为多个区域并采用不同的边界条件分别求解连续性方程,提出了一种考虑了载流子二维分布的改进的稳态解析模型,较准确地反映了IGBT基区过剩载流子分布,得到了更为准确的V-I特性仿真结果,通过实验验证了该模型的准确性.     

A-SMGCS机场场面运行控制的Petri网建模

以基本网模型为基础,阐述典型运行单元精细化模块构建方法与替代规则,生成场面精细化模型.采用航空器后续滑行路径对托肯进行着色以完成航空器建模,并给出精细化模型与航空器模型集成的方法,实现场面资源的动态竞争建模.以首都机场部分场面运行控制过程建模为例,验证所提建模方法的有效性和适用性.     

Asymptotic field of mode Ⅱ dynamic growing crack in visco-elastic material

A mechanical model of visco-elastic material is established in order to investigate viscous effect in dynamic growing crack-tip field of mode Ⅱ. It is shown that in stable creep growing phase, elastic deformation and viscous deformation are equally dominant in the near-tip field, the stress and strain have the same singularity, namely, (σε) ∝r^-1/(n-1). The asymptotic solutions of separatied variables of stress, stain and displacement in crack-tip field are obtained by asymptotic analysis, and the results of numerical value of stress and strain in crack-tip field are obtained by shooting method. Through numerical calculation, it is shown that the near-tip fields are mainly governed by the creep exponent n and Mach number M. By the asymptotic analysis to the crack-tip field, the fracture criterion of mode Ⅱ dynamic growing crack of visco-elastic materials is put forward from the point of view of strain.     

汽车外饰用耐候PC材料的开发及应用

汽车外饰灯具用PC材料通常还需在表面喷涂一层UV漆,以提高零件表面的耐光性能及耐磨性能。但对于结构设计复杂的灯具,工艺上无法实现UV喷涂,这就对灯具材料提出了更高的要求。为解决这类灯具对材料的要求,保证产品性能及工艺可实施性,开发了应用于汽车外部灯具的免喷涂、透明改性聚碳酸酯材料。介绍了材料开发机理及改性制备方法,该材料通过了全面的实验验证,并已成功应用。     

Lightweight mixture faults detection method for gasoline engine using on-line trend analysis

Mixture faults detection is meaningful for gasoline engines because proper mixture is the basic prerequisite for healthy running of a combustion engine. Among existing methods for faults detection, the data-driven trend analysis technique is widely used due to the simplicity and efficiency in time-domain. The CUSUM (Cumulative Sum Of Errors) algorithm is good at real-time trend extraction, but it’s easy to be costly on the fuel trim signal during the engine in normal working conditions, which will increase battery energy consumption because engine failure is rarely occurs. Hence, the conventional treatment methods of artifacts in the CUSUM algorithm are modified by means of decay function and detection time analysis. The thresholds are tuned according to the characteristics of artifacts instead of residual variability, which leads to better results of trend extraction and less computation. Then, the revised CUSUM algorithm is used for monitoring the mixture abnormal behaviors, and the mixture faults can be detected in real time through analyzing the variation features of fuel trim signal. The lightweight faults detector using the advanced CUSUM algorithm (FD-A-CUSUM) is evaluated on the experimental data collected from a Ford engine. The validation results show that while engine works under normal conditions, the computation of FD-A-CUSUM has decreased by 72.79 % in comparison with the detection method using the original CUSUM algorithm (FD-O-CUSUM), and the false alarm ratio of FD-A-CUSUM is 3.37 %. Futhermore, the detection results of FD-A-CUSUM for two leakage faults have achieved 91.18 % test accuracy.     

高填土U型桥台病害治理研究

结合内蒙古自治区乌海地区工程实际，就U型桥台高度与台身稳定性关系进行病害分析，并提出可行的加固方案及施工工艺。     

温度对离合器性能影响的研究

离合器作为整车传动系不可或缺的零部件,其使用故障多数为高温烧蚀,所以有必要深入了解温度与离合器性能之间的相互关系,找出影响离合器表面温度的因素和温度对离合器性能的影响,为整车离合器匹配设计提供支持。