多波段紫外辐照计设计

设计了一种多波段紫外辐照计.采用AlGaN基紫外探测器,利用可编程波段选择运算电路,通过对探测器输出信号的处理来测量UVA、UVB和UVC波段或整个UV波段的紫外辐射,测量结果由LCD显示.该多波段紫外辐照计灵敏度高、操作简单且体积小.     

Transpositional behaviour of the Ds element in the Ac/Ds system in rice

Insertional mutagenesis based on maize Activator/Dissociator (Ac/Ds) transposons is becoming a ma- jor approach used to produce a saturated mutant collection in rice. In this research, Ds-T-DNA trans- formed homozygotes were crossed with Ac-T-DNA transformed homozygotes in order to establish an Ac/Ds transposon system in rice. The successive investigation of Ds transposition from F1 to F5 gen- erations indicated that the frequencies of germinal transposition increased over successive genera- tions and reached 54.2% in F3 generation. The Ds transposition pattern revealed that a Ds transposition induced an approximately 170-bp deletion of T-DNA sequence and another Ds transposition carried a 272-bp T-DNA sequence. Using thermal asymmetric interlaced PCR (TAIL-PCR), some flanking se- quences of the Ds element were amplified. Analyses of 17 Ds-flanking sequences showed that five Ds were inserted into gene regions. The Ds could transpose not only to the linked sites but also to the unlinked sites. The frequency of inter-chromosomal transposition of Ds was 33.3%.     

A comparison of iron phthalocyanine and cobalt porphyrin on the electrochemical catalysis in Ni-MH battery

The effects of iron phthalocyanine （FePc） and cobalt porphyrin （CoPp） on inner pressure and cycle behavior of sealed Ni-MH batteries were investigated in this study. The morphology of battery electrode was observed by SEM. The electrochemical impedance spectroscopy of floating-charge/discharge battery was also measured. Experimental results show that the addition of FePc or CoPp to the alloy electrode is an effective approach to decrease the internal pressure of battery during the process of charge and overcharge. In contrast to CoPp, the battery with FePc exhibits a slower capacity decay and a smaller overpotential at the same charge-discharge rate. As an electrocatalyst, FePc may more effectively speed up the reduction of oxygen, and decrease its reduction potential. As a result, the charge process is accelerated, the gas evolution is reduced and the pulverization of electrode materials is slowed down.     

Tc>100K的Tl-Ca-Ba-Cu-O超导体

新近朱经武、赵忠贤、Hazen等人相继报导研制成Tc>100K的Bi-Sr-Ca-O和Tl-ca-Ba-Cu-O体系高温超导体,这是自1987年国际上掀起的超导热以来的又一次重大突破。我们选择名义成伤为Tl:Ca:Ba:Cu=2:2:1:3(简称2213)的配比作了初步研究。所用原料为Tl_2O_3,CaO,BaCO_3,CuO。由于Tl_2O_3,的熔点为717℃,低于BaCO_3的分解温度,远低于CaO、BaO和CuO的熔点。因此,将这四种原料直接混合在高温下烧结是难以得到预期结果的。特别是Tl_2O_3是剧毒化合物,高温下很易挥发,必     

圆柱螺旋弹簧可靠性优化设计

首先分析了圆柱螺旋弹簧静强度和疲劳强度可靠性模型建立方法,推导了其可靠性计算的公式和应力强度的分布形式.其次为充分发挥零件材料的效能同时又要考虑到零件的可靠性指标,以圆柱螺旋弹簧的质量为优化的目标函数,利用机械可靠性设计和机械最优化设计方法,在弹簧常规约束和可靠性约束基础上,建立了可靠性优化设计计算模型.最后,结合优化工具和上述优化模型对具体实例进行了应用计算,并分析对比了可靠性优化设计和常规优化设计的结果,说明所提可靠性优化设计方法实用、可靠,能最大程度地满足设计要求.     

超深稠油高温高压井筒降黏举升摩阻的实验研究

新疆塔河油田深层稠油在井筒举升过程中,由于温度的降低,原油逐渐失去流动性。稠油降黏是有效降低井筒举升摩阻的途径。根据现场掺降黏剂工艺,建立了室内高温高压井筒流动模拟实验装置,实验研究了温度、压力及流速对稠油井筒举升流动摩阻的影响,得到了不同降黏方式井筒举升摩阻梯度分布,在已有井筒压降计算模型的基础上,构筑了室内井筒流动模拟装置与实际井筒之间的压降换算关系,得到了不同降黏方式塔河原油在实际井筒中的压力分布。实验结果表明:原油在垂直井筒中举升摩阻随压力和流速的增加而增大,随着温度的升高而降低,但流速越大,井筒流动摩阻增加趋势渐缓。在井下3 000 m处掺降黏剂使稠油更易举升至井口,降黏效果为复合降黏剂油溶性降黏剂掺稀降黏。     

Effects of asymmetric rolling process on ridging resistance of ultra-purified 17%Cr ferritic stainless steel

In ferritic stainless steels, a significant non-uniform recrystallization orientation and a substantial texture gradient usually occur, which can degrade the ridging resistance of the final sheets. To improve the homogeneity of the recrystallization orientation and reduce the texture gradient in ultra-purified 17%Cr ferritic stainless steel, in this work, we performed conventional and asymmetric rolling processes and conducted macro and micro-texture analyses to investigate texture evolution under different cold-rolling conditions. In the conventional rolling specimens, we observed that the deformation was not uniform in the thickness direction, whereas there was homogeneous shear deformation in the asymmetric rolling specimens as well as the formation of uniform recrystallized grains and random orientation grains in the final annealing sheets. As such, the ridging resistance of the final sheets was significantly improved by employing the asymmetric rolling process. This result indicates with certainty that the texture gradient and orientation inhomogeneity can be attributed to non-uniform deformation, whereas the uniform orientation gradient in the thickness direction is explained by the increased number of shear bands obtained in the asymmetric rolling process.     

基于有界模型检测的门级软件自测试方法

提出了基于有界模型检测的门级软件自测试方法.将处理器中的模块简化成约束模块,缓解状态爆炸问题.将难测故障的触发条件逐个转化成性质并且采用有界模型检测技术,搜索触发这些性质的违例.最后,将违例映射成测试指令序列,并为测试指令序列添加观测指令序列,构成自测试程序.实验结果表明:该方法在不引起状态爆炸问题的情况下,有效地测试控制器中难以测试的故障,提高了在线测试的测试质量.