流动注射氢化物发生—原子荧光法中膜分相器和U管分相器…

本文在灵敏度，精密度，检出限，抗干扰能力，以及操作简易性和稳定性方面比较了流动注射氢化物发生法中膜分相器和Ｕ管分相器的分析性能，结果表明，两种分相器各有优缺点，均能满足地球化学品分析的要求，但膜的寿命短，需经常更换，是膜分相器的不足之处。     

LPT的RF分相偏置电路的研制

为了对兰州彭宁离子阱LPT内的离子运动进行偶极和四极共振激发,采用变压器原理,设计制作了两套分相器:一套工作频率为200 k Hz～4 MHz,适用于四极激发模式;另一套工作频率为1700～1750 Hz,适用于偶极激发模式。详细测试了它们在空载和负载情况下的幅频曲线与相频曲线。测试结果表明:RF分相偏置电路的输出幅度与相位均达到了设计要求。     

氟锆酸盐光纤玻璃中的析晶和分相现象

氟化物光纤玻璃中的夹杂物,分相颗粒和微晶颗粒等缺陷,造成光纤的散射损失,影响了实际制备工作.本文利用大视场光学显微镜,X射线衍射,透射电子显微镜和差热分析,研究了ZBLA氟化物玻璃中的分相和析晶现象,观察到了以成核生长机理进行的分相颗粒,析晶颗粒的成分是β-BaF_2·ZrF_4和α-BaF_2·2ZrF_4,通过DTA分析确定了这些相的析晶活化能.     

微型太阳敏感器光学掩模的镀膜设计

太阳敏感器是空间飞行器进行姿态确定和方位测定的重要器件，传统太阳敏感器大而重，无法应用到微小卫星特别是皮纳卫星上。介绍了基于CMOS APS探测器的微型太阳敏感器的工作原理，基于黑体辐射理论和太阳光谱特性，结合CMOS APS探测器工作特性，分析给出了这种敏感器像元表面产生光电子数的计算方法，并采用Matlab软件，编程计算了地球表面太阳垂直入射条件下，探测器像元表面产生的光电子数。采用光学薄膜设计方法，分析设计了掩模表面光学薄膜的膜系结构，计算了各膜层的透射特性。在此基础上，得到了基于CMOS APS探测器微型太阳敏感器光学掩模的光学薄膜的设计方法，最后给出了设计结果。     

软X射线多层膜单色器能量分辨研究

从理论上分析了影响软X射线多层膜单色器能量分辨率的机制，给出了一种既能提高多层膜能量分辨率又不影响其反射率的膜材选择规则．并给出近年来在北京同步辐射装置上开展多层膜单色器应用研究的结果 关键词：     

带有高压储液器的制冷系统建模研究

通过对制冷系统循环特性、变工况特性和参数间耦合特性的分析,遵循热力学基本定律和能量、动量、质量守恒定律,采用稳态和动态建模相结合的方法建立压缩式制冷系统的数学模型。针对换热器建模难点采用分相区和移动边界相结合的方法建立其集总参数动态模型,并且冷凝器与高压储液器相结合,构成冷凝器加储液器的整体部件,文中建立的制冷系统的整体模型,反映了制冷系统工况变化时制冷剂质量的重新分配及其对状态变量的影响,提高了系统建模的精度,最后通过实验对所建模型的准确性进行了验证。     

开架式气化器预冷过程海水膜传热分析

为了减少开架式气化器换热管表面结冰，设计一种新型高效换热管，并采用ANSYS Workbench软件对预冷过程中换热管表面海水膜温度场和速度场进行模拟。分析发现：结冰主要发生在预冷过程中的非稳定阶段，该阶段海水膜厚度影响温度场和速度场的分布，海水膜越厚，温度越高，速度越大；稳定阶段，海水膜厚度对温度场分布和接近冰点温度海水量的多少影响不大，而使海水膜速度分布逐渐趋于均匀，并在左右肋两侧形成四个涡旋，距离LNG进口端越远，旋涡运动越剧烈。     

肥皂膜过滤器的性能探究

物质分离是很多医疗和工业的核心技术.传统的固体过滤膜可以允许小于临界尺寸的粒子通过而阻挡大的粒子透过.然而，允许大粒子通过而小粒子停留的膜却很难人工制造.Birgitt Boschitsch Stogin、Luke Gockowski等人证明了完全由液体组成的液膜可以被设计成保留小于临界尺寸粒子而透过大尺寸粒子的过滤膜.基于上述研究，本文在液膜过滤器模型基础上进行解析推导，分析讨论了液膜的临界透过条件，并在实验中得到验证.同时，本文通过调节液膜表面张力系数实现了对粒子速度的筛选.     

光束定向器中膜厚不均匀性对远场性能的影响

讨论DF(氟化氘)强激光系统光束定向器中的光学薄膜，用偏振光线追迹分析定向器出瞳主激光、信标光偏振态变化，计算膜厚不均匀性对远场性能的影响．     

分相式热虹吸油冷却系统性能分析

对于螺杆式压缩制冷机组,润滑油的冷却是机组稳定、可靠运行的保证,而在几种冷却方式中,分相式热虹吸油冷却系统最适用于螺杆式压缩制冷机组。建立了分相式热虹吸油冷却系统的数学模型,研究了螺杆式压缩制冷机组的冷凝温度、液位高度差和连接管管径对系统换热性能的影响。结果表明:油冷却系统的换热量先随着液位高度差的增大而增大,然后保持稳定;连接管管径从32 mm变化至42 mm,油冷却系统的换热量提高12.2%～19.7%;冷凝温度升高会导致油冷却器内制冷剂的蒸发温度升高,削弱制冷剂和润滑油之间的换热能力,导致换热量降低。     

Performance Analysis of HFC-404A Vapor Compression Refrigeration System Using Shell and U-Tube Smooth and Micro-Fin Tube Condensers

Performance analyses of an HFC-404A refrigeration system for a smooth U-tube condenser and a micro-fin U-tube condenser are carried out for various operating conditions. This article mainly reports performance testing of the above-mentioned condensers for various operating parameters and their effect on the performance of refrigeration systems. The condensers used are shell and U-tube types, with refrigerant through a tube and cooling water through a shell. It also reports the performance enhancement of the system using a micro-fin tube condenser relative to a smooth-tube condenser system. The cooling capacity of the system is increased by 10%, and the coefficient of performance of the system is improved up to 17% using a micro-fin tube condenser.     

U型管传热量影响因素的数值模拟研究

地下换热器是地源热泵的重要组成部分,竖直U型管是最常见的地下换热器形式. U型管与土壤间的传热受诸多因素的影响.为分析这些因素对于U型管传热的影响,本文建立了地源热泵竖直U型管地下换热器的三维全尺寸数值模型,在此基础上采用CFD软件FLUENT对U型管的埋管深度、进口水温、管内流速等一系列因素在冬夏不同工况下对U型管传热量的影响进行了数值模拟研究.经过整理分析得出的各种因素对传热量影响可以为优化工程设计提供依据.     

The morphological evolution, mechanical properties and ionic conductivities of electrospinning P(VDF-HFP) membranes at various temperatures

Poly(vinylidene difluoride-co-hexafluoropropylene) [P(VDF-HFP)] membranes as separators for lithium-ion batteries were prepared from electrospinning. The morphological evolution of the separators at various temperatures were characterized by atomic force microscopy (AFM) equipped with a hot stage. We found the swollen effect of electrolytes on the P(VDF-HFP) phase through in situ observation. The electrochemical measurements results showed the ionic conductivity increased gradually with the increase of temperature. To evaluate the mechanical properties of the P(VDF-HFP) membranes at various temperatures, the tensile curves of the separators were also investigated.     

埋管换热器热阻分析

地源热泵系统中的竖直埋管换热器是地源热泵系统的一个关键部分,从U管内至岩土间的传热热阻影响热泵系统的性能.文中介绍在静态负荷下,利用垂直U型埋管换热器换热的一维模型和二维模型,从传热热阻的角度进行了埋管管径、钻孔直径与管内对流热阻、钻孔热阻间的分析,结果显示,对钻孔热阻与管径的优化选择可降低热阻,同时对提高埋管换热器的...     

Distribution of lithium in doped nuclear pores of polyethylene terephthalate by neutron depth profiling

In this paper, doping of porous polyethylene terephthalate membrane using Li-based solution is described and analyzed by nuclear analytic methods. In recent years, the polymeric porous membranes have been studied as advanced battery separators in various applications, such as portable electronic devices or electric vehicles. Apart from mechanical stability, the separators also provide electrical separation and ionic transport between the electrodes during charging and discharging processes. For application of the membranes, it is important to follow the Li distribution in the separator material over time. In this work, the distribution of Li in the porous PET foils, adepts for Li ion battery separators, was analyzed by Neutron Depth Profiling and the 3D shape of the etched pores by Ion Transmission Spectroscopy. The data obtained show that Li can be incorporated, in a passive way in the micropores in large quantities, but its amount is still limited and does not depend on time of doping. Here, the first data are presented.     

U型管地下换热系统非稳态传热数值模拟

地下换热器是地源热泵系统重要的组成部分,单U型管是当前广泛使用的地下换热器形式。本文建立了单U型管地下换热器的真实尺寸三维数值模型,通过模拟结果同试验实测数据的对比,验证了模型的正确性。本文随后对单U型管地下换热器在冬季工况下连续运行和间歇运行的换热率进行了数值计算,得出了换热率随时间变化的规律。本文还对连续运行工况下U型管作用半径随时间变化的规律进行了研究。本文得出的结果可以用来指导地源热泵工程的设计。     

Ultrasonic enhancement of battery diffusion

It has been demonstrated that sonic energy can be harnessed to enhance convection in Galvanic cells during cyclic voltammetry; however, the practical value of this approach is limited due to the lack of open volumes for convection patterns to develop in most batteries. This study evaluates the ability of ultrasonic waves to enhance diffusion in membrane separators commonly used in sandwich-architecture batteries. Studies include the measuring of open-circuit performance curves to interpret performances in terms of reductions in concentration overpotentials. The use of a 40 kHz sonicator bath can consistently increase the voltage of the battery and reduce overpotential losses up to 30%. This work demonstrates and quantifies battery enhancement due to enhanced diffusion made possible with ultrasonic energy.     

Sensitive and robust electrophoretic NMR: instrumentation and experiments

Although simple as a concept, electrophoretic NMR (eNMR) has so far failed to find wider application. Problems encountered are mainly due to disturbing and partly irreproducible convection-like bulk flow effects from both electro-osmosis and thermal convection. Additionally, bubble formation at the electrodes and rf noise pickup has constrained the typical sample geometry to U-tube-like arrangements with a small filling factor and a low resulting NMR sensitivity. Furthermore, the sign of the electrophoretic mobility cancels out in U-tube geometries. We present here a new electrophoretic sample cell based on a vertically placed conventional NMR sample tube with bubble-suppressing palladium metal as electrode material. A suitable radiofrequency filter design prevents noise pickup by the NMR sample coil from the high-voltage leads which extend into the sensitive sample volume. Hence, the obtained signal-to-noise ratio of this cell is one order of magnitude higher than that of our previous U-tube cells. Permitted by the retention of the sign of the displacement-related signal phase in the new cell design, an experimental approach is described where bulk flow effects by electro-osmosis and/or thermal convection are compensated through parallel monitoring of a reference signal from a non-charged species in the sample. This approach, together with a CPMG-like pulse train scheme provides a superior first-order cancellation of non-electrophoretic bulk flow effects.     

自然循环蒸汽发生器倒U型管内流动不稳定性判别准则

针对自然循环蒸汽发生器倒U型管内流动不稳定的特点,利用无量纲分析方法建立管内流体控制方程.采用小扰动分析方法,得到倒U型管内流动不稳定的判别准则.通过对某型蒸汽发生器进行计算分析,获得判别准则随流体进口温度和弯管半径变化规律.计算结果表明:随着流体进口温度的升高,特征雷诺数增加,但是不同流体进口温度条件下特征雷诺数随弯管半径的变化规律不同.相对于流体进口温度,弯管半径对特征雷诺数的影响较小.所得结论为蒸汽发生器倒U型管内倒流管空间分布及倒流流量计算提供理论依据.