氦液化循环中透平流量的优化及影响因素热力学分析

为了在氦液化循环中获得最大的液化率,采用MATLAB编程实现流程中的热力学计算,针对带液氮预冷的Collins循环中的透平流量(me_1、me_2)进行优化分析。首先根据前人已得到的结论验证了模型的正确性,在此基础上进行深入研究。结果显示,当固定流程中的高低压力、换热器有效度以及透平的等熵效率时,透平的分流量为压缩机入口总流量的74%并且两台透平均分时系统可获得最大的液化率,且这一最优流量并不随透平的等熵效率和换热器的有效度改变。     

动态力校准中力传感器端部等效质量测量方法研究

力传感器端部等效质量是动态力校准中的重要部分,其测量误差会对动态力校准产生较大影响。本文通过了解力传感器结构,确定力传感器端部等效质量的构成,并简单介绍了四种测量端部等效质量的方法。最后,利用两次配重消去法进行实验,将不同配合不同工况下得到的结果进行对比分析,说明该方法可以较好的解决测量端部等效质量问题。     

空气源热泵热水机组最佳运行时段模糊判定的研究

根据空气源热泵热水机组制热性能随环境温度升高而升高的规律,以热泵机组前一日开机时间和环境温度变化量作为输入量,设计机组当日开机时间的模糊判定控制系统,运用MATLAB软件验证模糊控制系统的效果。结果表明,该模糊判定控制系统可根据前一日开机时间和温度变量的变化情况,实时决定最佳运行时段,对提高热泵系统的节能性能具有重要意义。     

Dynamic analysis of laminated composite plates traversed by a moving mass based on a first-order theory

The dynamic response of angle-ply laminated composite plates traversed by a moving mass or a moving force is investigated. For this purpose, a finite element method based on the first-order shear deformation theory is used. Stationary and adaptive mesh techniques have been applied as two different meshing schemes. The adaptive mesh strategy is then used to avoid off-nodal position of moving mass. In this manner, the finite element mesh is continuously adapted to follow and comply with the path of moving mass. A Newmark direct integration method is employed to solve the equations of motion. Parametric study is directed to find out how different parameters like mass of the moving object as well as the type of the angle-ply laminated composite plates affect the dynamic response. Numerical results show the significant effects of the stacking order on the dynamic responses of the composite structures under a moving mass. It is found that although [30/−60/−60/30] lamination shows the highest maximum vertical deflection but [−45/45/45/−45] lamination has the highest value of the dynamic amplification factor. The dynamic amplification factor for different stacking orders and mass velocities is less than 1.25.     

用电喷雾质谱和特异 PCR 初步鉴定粳稻 GluB 蛋白突变体

用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)方法对采集于中国、日本、印尼、老挝的42份特异粳稻资源进行了分析.结果显示,在编号为B104的粳稻中有谷蛋白亚家族 GluB 基因沉默现象.将对照材料 B90 的对应蛋白进行回收染色、原位酶解,然后利用电喷雾-四极杆飞行时间质谱(ESI-Q-IOF-MS)技术进行鉴定分析.用 MASCOT 叩数据库进行比对的结果显示,该蛋白的推测分子量为 54kD,被包括 GluB2、GluB4、GluB7 等基因在内的 GluB 亚家族基因编码.为了深入探讨 CluB 蛋白的突变机制,设计了2对特异引物,以 B90 为对照,用基因组 PCR 方法来钓取并鉴定其中的 GluB4 和 GluB7 基因.鉴定结果表明 GluB7 基因在 DNA 水平上未发生变化,而 GluB4 基因发生了点突变,导致一个氨基酸的变异.研究证实,电喷雾电离质谱(ESI-MS)可以用来辅助解析植物蛋白质的复合体.     

Application of the theory of Markov chains to model heat and mass transfer between stochastically moving particulate and gas flows

A cell model to describe heat and mass transfer between two media, one or both of which are involved in stochastic motion, is proposed. The model consists of two chains of cells to describe 1D stochastic motion of the flows. Each couple of corresponding cells experiences heat and mass exchange at every transition. The model allows describing the transient process as well as the steady-state distribution of parameters of the flows. It allows taking into account such non-linear phenomena as phase transformation (boiling, for example) and the internal heat sources caused, for example, by chemical reactions. The examples of modelling given in the paper demonstrate the ability of the model to describe all necessary features of the process.     

Some methods for redefining the unit of mass standard fundamental problems in metrology

Contemporary methods are presented for redefining the unit of mass standard, i.e., the kilogram prototype. The main tendencies in improving these methods in order to reduce the uncertainty of reproducing the unit of mass are discussed. It is noted that the use of precise values of a number of fundamental physical constants, primarily the Avogadro number, is important. __________ Translated from Izmeritel’naya Tekhnika, No. 4, pp. 3–7, April, 2006.     

离子膜传质机理的研究评述

介绍近期有关离子膜传质机理方面的主要研究思路,包括采用不可逆热力学观点、三通道模型、毛细孔流模型以及“吸附-溶解”模式下的理论分析和实验研究情况,并对其结果进行评述．     

Nanosecond and femtosecond mass spectroscopic analysis of a molecular beam produced by the spray-jet technique

The spray-jet molecular beam apparatus enabled us to produce a molecular beam of non-volatile molecules under high vacuum from a sprayed mist of sample solutions. The apparatus has been used in spectroscopic studies and as a means of molecular beam deposition. We analyzed the molecular beam, consisting of non-volatile, solvent, and carrier-gas molecules, by using femtosecond- and nanosecond- laser mass spectroscopy. The information thus obtained provided insight into the molecular beam produced by the spray-jet technique.     

果胶超滤纯化过程传质模型和动力学分析

研究了果胶提取液超滤膜分离处理过程传质特征,建立了渗透通量、膜面浓度与压差的传质模型,并对膜阻力和浓差极化阻力进行了定量描述;同时对超滤过程的动力学进行了分析.     

微孔膜的可压缩性及参数变化对膜蒸馏跨膜传质速率的影响

针对两种聚四氟乙烯膜在膜两侧压差为10～100kPa范围内进行了气体渗透实验,结果表明：实验用膜具有一定的可压缩性,随膜两侧压差的增大,膜孔径r减小,而膜孔隙率与有效厚度的比值ε／τδ是增大的,且其变化幅度随膜厚度的增大而增大,通过求解数学模型方程得到了不同膜参数时直接接触式膜蒸馏和真空膜蒸馏跨膜传质速率的预测值,与相同条件下的膜蒸馏实验测定的传质速率进行对比,结果表明：由膜的可压缩性带来的膜参数变化能够使跨膜传质速率有所增长,采用相近压差下气体渗透实验测定的膜参数能够较准确地预测膜蒸馏的跨膜传质速率。     

表面活性剂对液膜分离传质性能的影响

研究了不同表面活性剂组成的液膜体系在分离过程中的传质、溶胀和渗透等性能,分别考查了聚胺型表面活性剂L-113A和LMA-1及酯型表面活性剂Span80对含P204载体液膜体系迁移镧(Ⅲ)的影响,以及L—113A、L—113B和EM-301对无载体液膜体系富集氨氮的影响．实验表明,因表面活性剂不同,造成乳状液膜体系在分离富集镧或氨氮时,分离传质性能相差较大,LMA—1—P204-煤油的液膜体系对镧具有最大的迁移能力。迁移率97．4％;而L-113A-膜相添加剂-煤油的液膜体系对氨氮的溶解渗透能力最大。迁移率为86．4％．另外,对因表面活性剂结构不同而造成油水界面黏度的差异以及对传质速率的影响,从乳状液膜和自组装双分子液膜等方面进行了探讨．     

How to improve the sensitivity of future neutrino mass experiments with thermal calorimeters

In this paper we discuss the perspectives for a new generation of neutrino mass experiments using thermal detectors to reach interesting sensitivities before and after the KATRIN experiment. By scaling the performance of the present Milano neutrino mass experiment with Monte Carlo simulations, we show how a new experiment can validate the present limit of few eV set by spectrometers before the KATRIN experiment starts. We also show how such a result can be used to design a very large thermal detector experiment to reach sensitivities beyond the KATRIN expected one.     

面向大规模定制的供应链驱动模型的研究与应用

大规模定制是在高效率的大规模生产的基础上,通过产品结构和制造过程的重组,运用现代信息技术,新材料技术、柔性技术等一系列高新技术,以大规模生产的成本和速度,为单个顾客或小批量多品种市场定制任意数量的产品的一种生产模式,本文提出了面向大规模定制的推拉型供应链驱动模式,构建了以装配为分离点的供应链模型,并进行了案例研究。     

管式间接蒸发空气冷却器传热传质模型的建立及验证

回顾和分析现有间接蒸发冷却器的热工性能和数学模型,并在分析管式间接蒸发空气冷却器传热、传质过程及特点的基础上,建立针对管式间接蒸发空气冷却器热工计算模型。基于模型中管外二次空气侧空气与水膜之间的传热、传质系数是影响模型精度的重要因素,对管外二次空气侧空气与水膜之间的传热、传质系数进行深入分析,将模型用于水平单管外蒸发传热、传质系数的计算,并将计算结果与文献中的实验数据进行对比,证明所选模型的正确性,为下一步对管式间接蒸发空气冷却器整体热工性能的数值模拟奠定坚实的基础。     

提高曲面近似展开精度的方法与实现

通过对不可展曲面近似展开精度的研究，提出了根据曲面曲率的大小对曲面自动进行网格划分，通过对综合展开误差数据场进行数据拟合来选取最优展开基点，基于空间曲面与其展开图间近似的等距变换关系进行展开样形的误差矫正等3种方法，这几种方法的实现在不同程度上有效地减小了曲面的近似展开误差，提高了曲面的近似展开精度。     

真空度对膜法溶解氧解吸过程传质性能的影响

采用中空纤维膜组件对水中溶解氧脱除进行了实验研究,测定了不同操作条件下溶解氧浓度随时间的变化关系,重点考察了真空度对中空纤维膜组件传质系数的影响,并获得了传质准数关联式.研究结果表明,系统真空度对水中溶解氧的传递过程有重要影响,且真空度越高,溶解氧脱除效果越明显,传质系数越大,并进一步影响传质准数关联式.     

TiO2光催化降解有机污染物机理和影响因素

半导体TiO2光催化降解有机污染物是目前涉及物理化学、材料科学和环境科学等学科领域的研究热点.介绍了TiO2光催化分解有机污染物的机理;着重探讨了光催化反应有机物、反应条件和TiO2光催化剂等三大因素对光催化反应过程和效率的影响.最后提出了在实际应用中提高光催化降解效率需要解决的问题和发展方向.     

Strategic orientations and mass customisation capability: the moderating effect of product life cycle

This study examines the influence of three strategic orientations (customer, competitor and innovation) on mass customisation (MC) capability via the organisational learning process known as customisation knowledge utilisation (CKU). The moderating effect of product life cycle (PLC) is also investigated. Using data collected from 204 manufacturers, we show that all three strategic orientations positively contribute to MC capability, both directly and indirectly through CKU. Further, our empirical findings suggest that the effects of customer, competitor and innovation orientation on MC capability are contingent on PLC. The effects of customer orientation on CKU and the effects of competitor orientation on CKU and MC capability are stronger when a product is in the maturity stage of its life cycle, whereas the effect of innovation orientation on CKU and MC capability are stronger in the growth stage. These findings suggest that to effectively improve MC capability, managers need to leverage external and internal orientations at different stages of the PLC.