高强度复合材料整铸辙叉前期研究

辙叉是线路上工作条件最为严峻的轨道部件之一。用高强度复合材料整铸的辙叉替代普通辙叉的研究具有重要意义。以ＰＤ３钢轨钢作为基体材料，在其表面熔合上一层新型具有更好耐磨性能的材质。新材料１、新材料２分别在ＰＤ３基础上把Ｖ的含量提高到０．１５％～０．２５％和０．３５％～０．４５％。采用合适的工艺措施，使新材料１、２与ＰＤ３轨道钢很好地熔合在一起。它们的σｂ、ａｋ、δ、τｂ均不低于ＰＤ３，而Ｈｖ却有了提高。     

陶瓷结合剂化学组成的计算与配方优化设计

本文利用计算机技术．对陶瓷结合剂化学成分进行精密计算．在此基础上，根据结合剂所需要的化学成分，采用数学模型精确优化设计出陶瓷结合剂配方(即各种原材料的配比)，文章介绍了上述算法具体实现方法，给出了算法模型和精确的程序语言描述，算法重点解决了误差放大．计算稳定性等工程计算问题，对实际系统运行样本数据进行了验证，同时，文章描述了算法所引用的数据库表的结构设计方法及提高数据库应用效率和灵活性的技巧；分析了整个软件系统模块组成，描述了系统功能。通过实际应用与测试．验证了该系统算法和软件系统的可用性，对研究开发新型陶瓷结合剂具有重要指导作用。     

Thermal analysis of laser surface transformation hardening—optimization of process parameters

This paper deals with the optimization of process parameters for maximum productivity (given by the product of scanning velocity and cross feed) in laser transformation hardening. The process parameters considered are laser beam power, P; laser beam diameter, D_b; and the heat intensity distribution, namely, normal, bimodal, or uniform. A thermal analysis of the laser surface transformation hardening of gears was conducted (based on Jaeger’s classical moving heat source method) by considering the laser beam as a moving plane (disc) heat source to establish the temperature rise distribution in the workpiece (gear) of finite width. In a recent investigation [Int. J. Heat Mass Transfer 44 (2001) 2845], the authors considered the case of a heat source with a pseudo-Gaussian (or normal) distribution of heat intensity. The analytical results were compared with the experimental results published in the literature. In laser heat treatment of steel, it is generally considered preferable to use a wider heat intensity distribution, such as uniform or bimodal, for it enables more uniform case hardening depth. In this paper, this model is extended to cover bimodal and uniform distributions and compared with the normal distribution. Scanning velocities for no surface melting and for a case hardening depth of 0.1 mm were determined for surface transformation hardening of AISI 1036 (EN 8) steel for a range of laser beam powers, P, laser beam diameters, D_b, and various heat intensity distributions. Since diffusion during the heat treatment (surface transformation hardening) process is a time dependent phenomenon, based on the literature review, an interaction time of 15 ms was taken as a basis. It is hoped that laser industry with adequate facilities available can validate the thermal analysis and subsequent optimization presented in this paper.     

钻杆环缝数控自动焊机

研制的钻杆环缝数控自动机焊为全自动的数控焊机。用于钻杆与两端法兰的内外共4条环缝的焊接。工件的上料、定位、夹紧、内外焊枪的到位、内外焊枪的焊接、自动排列焊道各层各道的焊接工艺参数的改变等均能自动进行。不同管径和不同壁厚采用的各种焊接参数都可在人机界面上预置。采用富氩混合气体保护焊工艺方法，焊缝美观，性能优良，几乎没有飞溅。经大量的生产实践证明该钻杆环缝数控自动焊机焊接质量好，生产效率高。     

渗硼层脆性判据K的物理本质

从实验和理论上对显微硬度压痕结合声发射测量渗硼层脆性的合理性及其脆性判据Ｋ的物理意义进行了讨论。Ｋ值可以反映渗硼层显微压痕裂纹长度随负荷增加的变化率，因而可以表征渗硼层的脆性。根据断裂力学可以导出入与Ｇ＿（ＩＣ）之间存在如下关系：Ｋ＝β（Ｇ＿Ｉ－Ｇ＿（ＩＣ））。Ｋ值间接反映了渗硼层的断裂韧性，可以作为定量评价渗硼层本质脆性的力学参量。     

生物形态多孔氮化钛陶瓷的碳热氮化法制备

研究了以生物模板(木炭)浸渍TiO2溶胶,高温碳热-氮化制备TiN陶瓷的工艺过程.应用热力学原理计算了经溶胶浸渍后形成的TiO2/C复合体系的氮化条件,确定了N2,CO分压对氮化温度的影响.采用碳热氮化法,在高浓度的氮气压力下反应烧结制备了具有生物形貌的多孔TiN/C陶瓷.结果表明在1400℃,4 h,0.5 MPa氮气压力下,得到了具有立方晶体结构的TiN/C多孔陶瓷,并保留了木材模板的显微结构.     

HA—微孔钛基涂层种植体的复合强度

研究了羟基磷灰石(HA)和中性玻璃(G)的混合涂料在TC4多孔钛基体上的界面复合强度。探讨了中性玻璃含量、基体表面状态以及烧结工艺对这种涂层复合种植体的复合强度的影响。指出:复合的实质是中性玻璃与基体的润湿结合,最合适的玻璃含量为50 wt%,提高复合强度的关键,在于基体表面的TiN蒸镀处理,当TiN厚度为2～3 μm时,复合强度可达7.2 MPa。最佳烧结工艺为:900～950℃/30 min。     

基于分块分形的工业CT图像缺陷自动定位算法

针对传统的缺陷定位必须经过图像分割和缺陷提取等步骤,识别过程比较麻烦而且费时,提出了一种基于分块分形的工业CT图像缺陷自动定位算法.该方法首先对图像进行分块处理,对每个分块区域进行分形维数计算.通过分形维数频域分布直方图进行阈值处理,标记边缘块,最后通过连通区域处理标记块,进而对缺陷进行标记定位.通过对含有不同缺陷数目的固体火箭发动机模型工业CT图像处理,均可以准确地定位缺陷.实验结果表明,该方法能有效、准确地自动定位工业CT图像缺陷,且具有较强的鲁棒性.     

Incorporating Intra‐Query Term Dependencies in an Aspect Query Language Model

Query language modeling based on relevance feedback has been widely applied to improve the effectiveness of information retrieval. However, intra‐query term dependencies (i.e., the dependencies between different query terms and term combinations) have not yet been sufficiently addressed in the existing approaches. This article aims to investigate this issue within a comprehensive framework, namely the Aspect Query Language Model (AM). We propose to extend the AM with a hidden Markov model (HMM) structure to incorporate the intra‐query term dependencies and learn the structure of a novel aspect HMM (AHMM) for query language modeling. In the proposed AHMM, the combinations of query terms are viewed as latent variables representing query aspects. They further form an ergodic HMM, where the dependencies between latent variables (nodes) are modeled as the transitional probabilities. The segmented chunks from the feedback documents are considered as observables of the HMM. Then the AHMM structure is optimized by the HMM, which can estimate the prior of the latent variables and the probability distribution of the observed chunks. Our extensive experiments on three large‐scale text retrieval conference (TREC) collections have shown that our method not only significantly outperforms a number of strong baselines in terms of both effectiveness and robustness but also achieves better results than the AM and another state‐of‐the‐art approach, namely the latent concept expansion model. © 2014 Wiley Periodicals, Inc.     

基于曲线拟合和SVM的眼动信号分类算法研究

为提高基于EOG的眼动信号分类算法精度,改进基于EOG的人—机交互系统性能,提出了一种基于曲线拟合(curve fitting)与支持向量机(SVM)的眼动信号分类算法(CF-SVM),并设计了新的实验范式,增加了“扫视保持”环节.该算法采用曲线拟合方法进行特征提取,在此基础上,使用SVM分类器对眼动信号进行分类.实验室环境下,对9名眼部活动正常的受试者进行了眼动数据采集与识别,CF-SVM算法的平均分类准确率达到98.3％,与其他几种眼动识别方法相比较,其平均正确率分别提升了9.4％、5.9％、1.0％.实验结果表明,CF-SVM算法在眼动信号识别中表现了良好的性能,具有高的分类精度和鲁棒性.