Start-up investigation on a dual-evaporator MPCL system

This paper describes the start-up process of a space activate thermal control system, two-phase mechanically pumped cooling loop (MPCL) with two evaporators, in ground-based testing. Each evaporator has an outer diameter of 3 mm and a length of 10 m and the total loop of the system is about 40 m. In this paper, the system design and work principle as well as the test setup of an MPCL are presented and the start-up processes of the MPCL are studied. The experiments on the start-up processes under different evaporative temperatures were carried out. Tests attention has been paid to the system performance characteristics such as differential pressure, absolute pressure, mass flow rate, main components temperatures and so on. During the start-up processes, the system presents a good stability and each part of the system performs a reasonable temperature wave, except some superheat phenomena in the evaporator which cause a pressure shock to the system. The superheat is mainly related to evaporative temperature and the initial liquid distribution in the evaporator. In general, the lower the evaporative temperature is the higher superheat occurs. When set-point evaporative temperature is ?15 °C, the differential pressure shock can reach 6.23 bar which is as 7.5 times as the stable state. In conclusion, the MPCL with dual-evaporators can be started up successfully and is an effective kind of thermal control technology for future space applications.     

台风莫拉克(2009)暴雨过程中位势切变形变波作用密度诊断分析和预报应用

在水平风场切变形变的基础上引入物理量——位势切变形变, 把水平风场的垂直分量和切变形变与广义位温的空间梯度结合起来. 该物理量的二阶扰动被定义为波作用密度, 在局地直角坐标系中推导了能够描述中尺度扰动系统发展演变的波作用方程. 对2009年登陆台风莫拉克引发的暴雨过程进行诊断分析, 结果表明, 台风中心区切变形变向涡度的转化显著, 该转化通过纬向风的经向梯度实现. 纬向风速的经向梯度与广义位温垂直梯度的耦合引起位涡和位势切变形变之间的转化, 以至于位势切变形变和位涡的异常值区分别位于台风环流的外侧和内侧. 波作用密度因能够描述水平扰动风场的垂直切变和切变形变以及凝 结潜热函数扰动梯度而与观测降水联系紧密. 相关统计分析表明, 2009年夏季波作用密度与6 h观测降水存在明显滞后相关性, 对未来6 h降水有一定的指示意义. 另外, 波作用密度通量散度和扰动非地转风位涡是影响波作用密度局地变化的主要物理因素. 基于波作用密度与观测降水的良好相关性, 建立了波作用密度暴雨预报方程. 2009年登陆台风"苏迪罗", "天鹅", "莫拉菲"和"巨爵"的暴雨预报个例分析和长时间序列的ETS评分计算表明, 波作用密度对台风暴雨具有较好的预报效果, 其预报降水能力略优于美国全球预报系统(GFS)的直接降水预报. 关键词： 位势切变形变 波作用密度 波作用通量散度 台风暴雨     

嵌入式超薄微晶纤维素/碳糊电极的构建及应用

以镍铬合金为基体,在其表面通过直接嵌入微晶纤维素修饰的碳糊膜,构建了嵌入式超薄微晶纤维素/碳糊电极(ISM/CPE). 用扫描电子显微镜和循环伏安法表征了电极的特性;以抗坏血酸(AA)为目标物考察其在该电极上的电化学行为. 结果表明,在ISM/CPE上,AA的氧化峰电位为0.38 V,较传统碳糊电极负移了0.05 V;峰电流与AA的浓度在1.0×10-6～1.0×10-3 mol/L范围内呈良好线性关系,相关系数r=0.999 3,检测限(S/N=3)为7.5×10-7 mol/L. 表明合金表面嵌入的超薄微晶纤维素/碳糊膜,改变了基体电极的电化学性质,可用于实际样品中AA的测定.     

强流回旋加速器中心区模型试验装置上偏转板和中心区技术研究

中心区模型试验装置是进行强流回旋加速器关键技术研究的实验平台.本文介绍了为该试验装置所设计的偏转板和中心区,包括物理设计的考虑、数控加工技术及安装精度的控制技术.由于电磁场的相互作用粒子在偏转板中的的轨迹为螺旋线,其电极形状复杂,加工采用四轴联动以上的数控机床完成.为满足束流动力学的需要,中心区的电极结构比较复杂而且不规则,表面光洁度要求高,另外尺寸和安装位置精度要求严格.中心区曲面电极结构由三轴联动加工中心加工完成,中心区地电极与高频D板头部的电极间隙非常重要,在安装过程中,制作了专用的"电极间隙通止规"控制电极间隙精度在±0.05mm.     

双(4-吡咯基-1'-苯基)甲烷(醚、砜)的合成及表征

用ω-溴代对氯苯乙酮、ω-溴代对溴苯乙酮和乙酰丙酮为原料, 分别合成了二种3-对卤代苯甲酰甲基-2,4-戊二酮(1a和1b), 进而与芳香二胺2a～2c通过Paal-Knorr反应合成了多取代对称双吡咯3a～3c, 4a～4c, 并通过红外光谱、紫外光谱、质谱、核磁共振氢谱及元素分析对化合物进行了表征.     

钨硅酸银纳米晶：形貌可控合成与表征

通过聚电解质(表面活性剂)作为导向剂的液相合成路线，合成了多种形貌的多金属氧酸盐纳米晶，包括纳米球，纳米带，纳米片，纳米立方体，六角纳米粒子，三角纳米粒子，雪花状纳米粒子。形状独特的六角形空心纳米粒子也通过相似的方法合成出来。在反应过程中，银离子通过配位作用吸附在聚电解质的组装结构上，通过与氮原子或氧原子的配位作用被定位在聚电解质上，从而导致规则形貌的多酸纳米粒子的形成。结果表明，产物的形貌极大地取决于表面活性剂的组装结构和它们与反应物间的配位作用。     

Synchronization in a Mutualism Ecosystem Induced by Noise Correlation

Understanding the cause of the synchronization of population evolution is an important issue for ecological improvement. Here we present a Lotka-Volterra-type model driven by two correlated environmental noises and show, via theoretical analysis and direct simulation, that noise correlation can induce a synchronization of the mutualists. The time series of mutual species exhibit a chaotic-like fluctuation, which is independent of the noise correlation, however, the chaotic fluctuation of mutual species ratio decreases with the noise correlation. A quantitative parameter defined for characterizing chaotic fluctuation provides a good approach to measure when the complete synchronization happens.     

Monitoring of Dynamic Behavior of Phospholipids at Liquid/Liquid Interfaces by a Time-Resolved Quasi-Elastic Laser-Scattering Method

Phospholipids, which consist of a zwitterionic head group connected to a pair of long hydrocarbon chain, constitute the major component of most cell membranes. A monolayer composed of phospholipids at the interface between two immiscible liquids is a useful model system for studying biological and artificial membranes.     

GdVO4:Ln3+(Ln=Eu，Tm，Dy)荧光粉的水热法制备及其发光性能

以EDTA为矿化剂,采用水热法制备了GdVO₄:Dy³⁺、GdVO₄:Dy³⁺,Eu³⁺和GdVO₄:Dy³⁺,Eu³⁺,Tm³⁺荧光粉,研究了所制备样品的相结构、形貌、荧光性质、Dy³⁺到Eu³⁺的能量传递及Dy³⁺的⁴F_9/2→⁶H_15/2跃迁的衰减曲线。X射线衍射(XRD)确定了所合成的GdVO₄:0.03Dy³⁺、GdVO₄:0.03Dy³⁺,0.07Eu³⁺和GdVO₄:0.03Dy³⁺,0.07Eu³⁺,0.07Tm³⁺样品均为四方晶系;扫描电镜(SEM)显示GdVO₄:0.03Dy³⁺,0.07Eu³⁺和GdVO₄:0.03Dy³⁺,0.07Eu³⁺,0.07Tm³⁺均为棒状结构,平均长度分别约为0.458和0.491 μm;通过研究GdVO₄:Dy³⁺,Eu³⁺的发射光谱和衰减曲线,佐证了Dy³⁺到Eu³⁺的能量传递过程,并确定了其能量传递的机制为偶极-偶极相互作用。通过调节GdVO₄:0.03Dy³⁺,xEu³⁺荧光粉中Eu³⁺的掺杂浓度实现了准白光输出(0.424,0.350);调节GdVO₄:0.03Dy³⁺,0.07Eu³⁺,yTm³⁺荧光粉中Tm³⁺的掺杂浓度,也实现了白光输出(0.346,0.301)。     

(BaxY1-x)CuO3-y系统的超导电性

本文系统地分析了组份和制备条件(包括热处理温度、时间等)对超导氧化物(Ba_xY_1-x)CuO_3-y正常态电子输运特性和超导临界温度的影响。在x=0-0.55的组份范围内,系统经历了从半导体(绝缘体)到金属(超导体)的转变;随着组份x的增大,超导临界温度T_c单调上升。结合物相分析的结果,对该系统的高温超导电性机制和正常态输运特性作了讨论。