INVESTIGATION OF HYDROGEN DISTRIBUTION IN METALS BY TRITIUM AUTORADIOGRAPHY

氚自射线照相法是观察低含量氢微观分布的有效手段之一。本工作利用氚示踪法研究:1.在不同纯度Fe中氢的分布规律;2.在局部应力状态下氢的扩散行为;3.在液相烧结钨合金中氢的分布;4.氢在堆焊接头不同区域的分布特征。实验结果表明,氢的分布特性与相结构、应力状态和碳陷阱有关。     

Preparation and properties of magnetorheological elastomers based on silicon rubber/polystyrene blend matrix

Magnetorheological (MR) elastomers, which are mainly composed of magnetic particles and elastic polymer, are a new kind of smart materials whose modulus can be controlled by changing the strength of magnetic fields. In this article, MR elastomers based on immiscible silicon rubber/polystyrene (SR/PS) blend matrix were fabricated successfully via cosolvent method and the MR effect, electric and mechanical properties, and the microstructures of the corresponding materials were studied. SEM studies showed that the dispersion of iron particles in blend matrix were different from that in single polymer, which could be further proved by the different electric conductivity. The MR effect of MR elastomers based on blend matrix varied with the different ratios of SR and PS, which was discussed in detail from the special dispersion of iron particles and of zero‐modulus of MR elastomers. In addition, the MR elastomers based on SR/PS blend matrix had enhanced mechanical properties, which made them more hopeful to be applied in practice. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3143–3149, 2007     

无线局域网中鉴权功能的实现

介绍无线局域网的系统结构,提出一种利用IP接入技术和蜂窝鉴权理论实现无线局域网鉴权工作的结构,并详细分析了工作流程。     

GPS信号发生器射频模块的一种实现方案

为了测试GPS（Global Positioning System）接收机的性能，需要用GPS信号发生器来模拟各种条件下的真实GPS信号。国外高性能GPS信号发生器的功能已经相当完善，但其核心技术对我国高度保密，而且市场上的GPS信号模拟器售价比较高。因此，自主研制GPS信号模拟器对我国的国防建设具有重大意义。本文介绍了GPS信号发生器射频模块的一种较优的实现方案，该方案采用移相法实现频率调制，具有电路实现简单、灵活性较大、性能指标较高等特点。     

A novel weighted fuzzy LDA for face recognition using the genetic algorithm

Fuzzy linear discriminate analysis (FLDA), the principle of which is the remedy of class means via fuzzy optimization, is proven to be an effective feature extraction approach for face recognition. However, some of the between-class distances in the projected space after FLDA may be too small, which can render some classes inseparable. In this paper we propose a weighted FLDA approach that aims to increase the smallest of the between-class distances. This is accomplished by introducing some weighting coefficients to the between-class distances in FLDA. Since the optimal selection of these weighting coefficients is not tractable via standard optimization techniques, the genetic algorithm is adopted as an alternative solution in this paper. The experimental results on some benchmark data sets reveal that the proposed weighted fuzzy LDA can improve the worst recognition rate effectively and also exceed LDA and FLDA’s average performance index.     

广东石油分公司天然气加气业务发展战略研究

世界各国面临气候变化的挑战,人们将目光投向最清洁的化石能源——天然气。天然气也是汽车理想的替代燃料,以开拓天然气零售和直分销业务作为燃气业务拓展主攻方向,抢占先机积极推进天然气加气网点建设投营和天然气直分销业务,快速提高天然气市场占有率已成为广东石油的发展战略。     

Construction of (2k,k, 2) Convolutional Codes with Double-Loop Cyclic Codes

In this paper, by taking multiple-time information in blocks into the coding of linear block codes, a new class of (2 \(k\) , \(k\) , 2) convolutional codes is constructed, by which a new way of constructing long codes with short ones is obtained. After that, the type of embedded codes is determined and the optimal values of the linear combination coefficients are derived by using a three-dimensional state transfer matrix to analyze and testify the constructing mechanism of the codes. Finally, the simulation experiment tests the error-correcting performance of the (2 \(k\) , \(k\) , 2) convolutional codes for different value of \(k\) , it is shown that the performance of the new convolutional codes compares favorably with that of traditional (2, 1, \(l\) ) convolutional codes.     

一种破片高回收率射孔弹壳体破碎特性的设计方法研究？

针对油气井下作业后射孔弹壳体破片对井筒的污染等负面影响,文中对射孔弹壳体爆炸后形成大尺寸破片的影响因素进行了试验研究,通过改变壳体厚度、材料、外部刻槽参数,进而改变壳体破裂后的破片尺寸,增加破片回收率。结果表明：壳体厚度为6.0 mm、材料为20＃钢、壳体外表面刻4条槽、槽宽为3.0 mm、槽深为4.0 mm时,通过单发射孔弹破片收集试验可得尺寸≥9.53 mm的破片,回收率可达83.1％,使得大部分壳体破片滞留在射孔枪体内,有效减少壳体破片对井筒的污染,降低射孔作业卡枪事故发生的风险。