基于协方差矩阵变换的相干源个数估计

正确地估计信号源个数是高分辨阵列信号处理的一个重要组成部分,本文提出了一种相干源个数估计的方法。这种方法是先采用空间平滑技术对信号源去相关,然后对阵列协方差进行酉变换,最后用基于协方差矩阵变换的信息论准则和盖氏半径(Gerschgorin Radii)两种方法估计信号源个数。计算机仿真结果证实了方法的可行性。     

钛及钛合金电弧钎焊及接头强度

用Ti—Cu—Ni，Ti-Cr-Zr钎料在TIG电弧加热条件对TA2和Ti—6Al—4V钛合金进行钎焊。结果表明：用Ti—Cu—Ni钎料钎焊TA2和Ti—6Al—4V钛合金的搭接接头强度分别是418．3MPa和439．6MPa；用Ti—Cr—Zr钎料钎焊TA2和Ti—6Al—4V钛合金的搭接接头强度分别是575．2MPa和656．1MPa。对Ti-Cu-Ni钎料／母材界面分析认为固液异分化合物η相((Cu，Ni)Ti2)生成时呈笋状生长，嵌入钎缝对钎缝的强度提高有利。对Ti-Cr-Zr钎料／母材界面分析，认为主要是固溶体β-Ti(Cr)存在提高了钎缝强度。     

A UNIFIED FRAMEWORK OF TARGETED MARKETING USING CUSTOMER PREFERENCES

One of the fundamental tasks of targeted marketing is to elicit associations between customers and products. Based on the results from information retrieval and utility theory, this article proposes a unified framework of targeted marketing. The customer judgments of products are formally described by preference relations and the connections of customers and products are quantitatively measured by market value functions. Two marketing strategies, known as the customer‐oriented and product‐oriented marketing strategies, are investigated. Four marketing models are introduced and examined. They represent, respectively, the relationships between a group of customers and a group of products, between a group of customers and a single product, between a single customer and a group of products, and between a single customer and a single product. Linear and bilinear market value functions are suggested and studied. The required parameters of a market value function can be estimated by exploring three types of information, namely, customer profiles, product profiles, and transaction data. Experiments on a real‐world data set are performed to demonstrate the effectiveness of the proposed framework.     

TiAl/Ti/V/Cu/40Cr钢扩散连接界面组织结构对接头强度的影响

研究了TiAl/Ti/V/Cu/40Cr钢的扩散连接，结果显示：在TiAl/Ti界面处形成了对接头强度有利的Ti3Al TiAl双相层及Ti固溶体层，而Ti/V/Cu/40Cr界面处未出现金属间化合物及其它脆性相，接头最高拉伸强度可达420MPa，接近TiAl母材。     

Evaluating information retrieval system performance based on user preference

One of the challenges of modern information retrieval is to rank the most relevant documents at the top of the large system output. This calls for choosing the proper methods to evaluate the system performance. The traditional performance measures, such as precision and recall, are based on binary relevance judgment and are not appropriate for multi-grade relevance. The main objective of this paper is to propose a framework for system evaluation based on user preference of documents. It is shown that the notion of user preference is general and flexible for formally defining and interpreting multi-grade relevance. We review 12 evaluation methods and compare their similarities and differences. We find that the normalized distance performance measure is a good choice in terms of the sensitivity to document rank order and gives higher credits to systems for their ability to retrieve highly relevant documents.     

User-centric query refinement and processing using granularity-based strategies

Under the context of large-scale scientific literatures, this paper provides a user-centric approach for refining and processing incomplete or vague query based on cognitive- and granularity-based strategies. From the viewpoints of user interests retention and granular information processing, we examine various strategies for user-centric unification of search and reasoning. Inspired by the basic level for human problem-solving in cognitive science, we refine a query based on retained user interests. We bring the multi-level, multi-perspective strategies from human problem-solving to large-scale search and reasoning. The power/exponential law-based interests retention modeling, network statistics–based data selection, and ontology-supervised hierarchical reasoning are developed to implement these strategies. As an illustration, we investigate some case studies based on a large-scale scientific literature dataset, DBLP. The experimental results show that the proposed strategies are potentially effective.     

均匀设计法在粉末氯丁橡胶制备中的应用

以高分子树脂为包覆剂，采用凝聚包覆法将CRl21型氯丁胶乳制备成粉末氯丁橡胶。用均匀设计法研究了制备工艺路线中的主要4个因子(氯化钠、包覆剂M81、包覆剂M82和脂肪酸盐)对产物粒径分布以及物理机械性能的影响，并用回归分析法拟合了产物的粒径分布和物理机械性能与主要变量之间的试验数据，在试验范围内预测产物的性能并作了验证。结果表明，4个影响因子对硫化胶拉伸强度和扯断伸长率的影响不显著，但对产物中1-3mm和小于1mm粒子所占的质量分数、500％定伸应力、邵尔A型硬度和永久变形的影响很显著。     

宝钢纯净钢生产技术进步

重点叙述了宝钢在钢中碳、氮、氧、磷、硫以及夹杂物控制方面的技术进步.并介绍了宝钢IF钢、管线钢所达到的纯净度综合水平.     

ZnO:Al(AZO)薄膜制备工艺参数的正交优化设计

采用正交设计法,对溶胶-凝胶方法制备AZO薄膜的工艺参数进行了优化研究;确定了最佳工艺参数,为制备AZO薄膜的工业化控制提供了一种可行的方法。     

MB2-LY12扩散焊接头界面组织结构及其形成机制

采用真空扩散焊接技术进行镁合金（MB2）与铝合金（LY12）的焊接,采用超声波无损检测,电子探针、X射线衍射和扫描电镜等手段研究了焊接温度对焊接接头界面附近组织结构的影响,分析了界面反应物的生成机理。结果表明,随着焊接温度的升高,焊接界面的焊合率提高,在焊接压力为3 MPa、保温时间为100 min的条件下,温度升高到480℃完全焊合,在Al侧和Mg侧分别形成了A1（ss,Mg）和Mg（ss,A1）固溶体,焊接界面形成了Al₁₂Mg₁₇、AlMg、Al₃Mg₂三种金属间化合物层,其厚度随着焊接温度的升高而增加,其中AlMg层厚度增长得最快,接头断裂发生在金属间化合物层且呈阶梯状断裂。界面扩散区的形成主要由有效物理接触阶段、固溶体形成阶段、金属间化合物相形成阶段以及金属间化合物增长阶段组成。