A SQUID gradiometer module with large junction shunt resistors

A dual-washer superconducting quantum interference device(SQUID) with a loop inductance of 350 pH and two onwasher integrated input coils is designed according to conventional niobium technology. In order to obtain a large SQUID flux-to-voltage transfer coefficient, the junction shunt resistance is selected to be 33 ?. A vertical SQUID gradiometer module with a baseline of 100 mm is constructed by utilizing such a SQUID and a first-order niobium wire-wound antenna.The sensitivity of this module reaches about 0.2 fT/(cm·Hz1/2) in the white noise range using a direct readout scheme, i.e.,the SQUID is directly connected to an operational amplifier, in a magnetically shielded room. Some magnetocardiography(MCG) measurements with a sufficiently high signal-to-noise ratio(SNR) are demonstrated.     

Superconducting quantum interference devices with different damped junctions operated in directly coupled current- and voltage-bias modes

We investigate niobium thin film superconducting quantum interference devices （SQUIDs） with different Steward- McCumber parameters βc operated in both current- and voltage-bias modes. We experimentally prove that there is no difference between the two bias modes with respect to the SQUID intrinsic noise and the noise contribution from the preamplifier. Furthermore, the relationships of the SQUID dynamic parameters, （Rd）current bias ≈ （Rd）voltage bias and （σV/σФ）current bias ≈ [σi/σФ）Rd]voltage bias, are always satisfied. For a strongly damped SQUID withβc ≈ 0.25, addi- tional positive feedback （APF） and noise cancellation （NC） were employed to enhance σV/σФ, the former showing a degradation in the linear flux range but otherwise the same with NC. For a weakly damped SQUID with βc ≈ 3, it is di- rectly connected to the preamplifier without APF or NC, and a low SQUID system noise of about 4μФ0/x/Hz is measured, which is close to its intrinsic noise.     

基于低温超导量子干涉器件的脑 听觉激励磁场探测

本文利用磁屏蔽室和二阶轴向梯度计抑制环境磁场噪声, 建立了单通道脑磁探测系统, 并对不用声音频率下脑听觉激励磁场N100m响应进行了初步探测.结果显示, 1000 Hz音频和100 ms持续声音激励下, N100m峰值的典型强度约为0.4 pT.在低的声音频率激励下, N100m峰出现延时, 100 Hz 和1000 Hz之间的延时差别达到25 ms.相比于1 kHz特定频率的声音激励, 1—4 kHz 随机变频下的N100m峰幅度增强, 出现了数毫秒的延时.本研究为下一步利用软件梯度计进行多通道脑磁系统和听觉机理研究奠定了一定的基础.     

LaNi5型储氢合金表面修饰及其电化学性能研究

0引言近年来,随着科学技术水平的提高和世界范围环保意识的增强,汽车尾气所造成的环境污染问题日益引起人们的重视[1]。电动汽车的发展可以有效制约燃油汽车所造成的环境污染。MH/Ni电池是一种无污染的“绿色能源”,它具有高比能量、高比功率、长寿命及安全性好等优异性能,非常     

响应面法优化深共熔溶剂提取烟草花序中的西柏三烯二醇

为实现烟草花序中西柏三烯二醇的绿色提取,以烟花作为原料,通过比较23种新型绿色溶剂——深共熔溶剂对烟花中西柏三烯二醇的提取效果,得到最适宜烟花中西柏三烯二醇提取的深共熔溶剂是氯化胆碱/1,4-丁二醇。在单因素实验的基础上,通过响应曲面设计(BoxBehnken Design),优化深共熔溶剂提取烟花中西柏三烯二醇的最佳条件。结果表明,最佳提取条件为:深共熔溶剂含水率为31%(V/V),提取温度为57℃,提取时间为30 min,料液比为10 mg/m L。在此条件下,西柏三烯二醇提取率为8.95 mg/g。通过与传统有机溶剂提取烟花中西柏三烯二醇的结果比较,深共熔溶剂可应用于烟花中西柏三烯二醇的提取,并且是一种绿色的提取溶剂。     

1,2,3-三唑取代的1,4-二氢-4-氧代-1,5-二氮杂萘-3-羧酸衍生物的设计、合成与HIV整合酶抑制活性评价

一价铜催化端炔与叠氮化物的1, 3-环加成反应是一种快速构建小分子库并筛选其可能性质的的主要方法。本文报道了1,2,3-三唑取代的1,4-二氢-4-氧代-1,5-二氮杂萘-3-羧酸衍生物的设计与合成。在该类化合物中,疏水性与亲水性片段通过Click反应有效地连接。所设计化合物8和12的结构通过光谱手段进行了表征;其可能的HIV整合酶抑制活性也进行了筛选。     

超导量子干涉器件读出电路中匹配变压器的传输特性研究

在磁通调制超导量子干涉器件(SQUID)的读出电路中, 匹配变压器具有放大信号和阻抗匹配的功能, 是实现SQUID低噪声读出的关键元件. 利用模拟SQUID电路对匹配变压器进行性能测试, 研究了不同绕制匝数变压器的传输特性, 确定最佳绕制匝数比. 在变压器拾取SQUID电压信号的耦合网络中, 研究了不同电容对变压器传输特性的影响, 实现了变压器耦合网络参数的匹配和优化. 室温下匝数比为1:20的匹配变压器在匹配电容C=1μF时, 输出源电压增益为21.2, 带宽范围可达到210 kHz. 最后在基于磁通调制式DC SQUID读出电路中, 对匹配变压器的工作性能进行了评估与验证. 关键词： 超导量子干涉器件读出电路 匹配变压器 低噪声 传输特性     

Multichannel fetal magnetocardiography using SQUID bootstrap circuit

Fetal magnetocardiography （MCG） is a sophisticated non-invasive technique for the fetal heart diagnosis. We constructed a multichannel fetal MCG system based on a novel superconducting quantum interference device （SQUID） direct readout scheme called SQUID bootstrap circuit （SBC）. The system incorporates four SBC gradiometers for the signal detection and three SBC magnetometers as the references. The fetal MCG signal at a 28-weeks’ gestation was measured. By the fetal MCG signal separation and average, the P-wave and QRS complex can be clearly identified. These results indicate that the SBC is one of the most promising techniques for the fetal MCG recordings.     

基于虚功原理建立套管外挤力学模型

为了准确地描述侧向载荷作用下套管发生挤毁变形,假设在发生塑性变形时套管的受力变形区形状为对称的两个弧形,基于虚功原理建立侧向载荷作用下的套管损坏力学平衡关系,引入菲涅耳积分推导出套管损坏力学模型.并结合大庆油田工程实际进行了套管挤毁实验,得出新公式的平均相对误差远远小于API公式的平均相对误差,从能量角度出发,为研究在外挤载荷下套管挤毁变形提供新的研究方法,为以后研究相关设计提供参考.     

大型电站锅炉炉内三维燃烧温度场可视化实验研究

本文利用 8只火焰图像探测器和相应的计算机图像采集处理系统,在一台 200 MW 四角切圆燃煤锅炉上进行了炉膛三维温度场可视化实验研究。现场实验结果表明,炉膛上部温度分布较低,并且呈典型的单峰形状;燃烧器区域的温度分布较高,能够反应四角切圆燃烧特性。用水冷枪抽气热电偶对温度场可视化结果进行了检验,相对误差在5％之内。三维温度场可视化结果刷新一次的时间不超过5秒,满足在线监测的要求。