High-Tc dc-SQUID magnetometer and its application in eddy current non-destructive evaluation

We have fabricated and tested a high-T_c dc-SQUID magnetometer patterned on a YBCO thin film deposited on a SrTiO₃ bicrystal substrate. The measurement of noise spectrum at 77 K showed that the magnetometer has a white noise of 333 fT/Hz^1/2 without superconducting shield, corresponding to a flux sensitivity of 14.5 μΦ₀/Hz^1/2. We constructed a test system for eddy current non-destructive evaluation of conducting aluminum plates by using the magnetometer. Flaws over 10 mm below the surface can be clearly identified. By mapping the magnetic field distribution, we can locate the flaw position. The signals caused by flaw were expanded due to the use of double-D type driving coil with a wider central slit. The experimental results confirmed that this test system could operate in a magnetic unshielded environment.     

O—O数据模型中实体联系的表达方法

具有对实体和实体间联系的描述能力，是数据库的基本，吼是对数据库进逻辑设计的基本出发点。Ｏ－Ｏ数据模型不具备显式描术这实体联系的手段。且优于关系模型。     

地震数据采集系统中频谱均衡滤波器的理论设计

地层的高频吸收衰减效应是导致地震勘探分辨率不高的主要原因，在高分辨率野外地震数据系统中，频谱均衡滤波器所设置的重要部件。文章以频谱均衡滤波器的原理和地层吸收衰减特性为基础，用计算机模拟的方法研究地层吸收衰减使分辨率降低的程度和频谱均衡滤波器对分辨率的补偿效果，给出了较好的频谱均衡滤波器的设计方案。     

激光热源形成过程的定量描述

研究了热传导方程的通解，进而提出激光热源形成的微观机理和热源形成过程的三个理论计算式。对激光热效应的应用具有指导意义。     

The TDCPR Management Mode of Engineering Equipment

The Three Gorges Project is a very large project,and its structure is very complex.Interna-tional advanced engineering equipment is broadly used.The state of equipment running directly influ-ences project building qualities and limited time.According to the factud conditions of the Three Gor-ges Project,the characteristics of engineering equipment are analyzed.At the same time ,some theories about equipment management are induced ,and the TDCPR management mode of engineering equip-ment of the Three Gorges Project is put forwared in order to gain the aim of managing and using equip-ment well and speeding up the project construction.     

抗氧剂于有机PTC热敏导电材料性能的稳定作用研究

探讨了抗氧剂在聚乙烯 乙烯 醋酸乙烯酯共聚物 炭黑 (PE EVA CB)体系中的作用。结果表明 ,在体系中加入抗氧剂可以提高材料体系的结构稳定性 ,从而可以在一定程度上改善材料的热电稳定性。当在体系中加入 2 .0 %(w)的抗氧剂时可收到良好效果。     

令牌多环网性能—可靠性综合评价

网络的性能与可靠性已分别得到广泛的研究,然而,怎样分析具有容错机制的环网的性能仍属有待开拓的研究领域,本文提出了一种分析具有自修复机制的多环网络系统的方法,并给出了报文传输时间分布的拉氏变换式,平均等待时间及平均队列长度公式,分析结果可用于评估故障与修复过程对实时令牌环网的实时响应特性的影响,对基于LAN的分布式实时系统设计具有指导意义。     

连铸铝镇静钢的钢水准备

在连铸生产铝镇静钢时,水口絮流一直是困扰工程技术人员的一个难题.从絮流的原因入手,分析了Al2O3生成的控制.并介绍了几种钢水钙化的方法,从中比较出用复合造渣材料来解决浇铸铝镇静钢的优点.     

欧盟邻苯二甲酸盐新规明年实施

欧盟最新颁布的关于邻苯二甲酸盐的新指导标准（第2005／84／EC），将于2007年1月16日起开始执行。