Bi3+对纳米MnO2水热合成的影响研究

在中性和酸性条件下，以MnO2作为锰源，通过水热合成了纳米MnO2，通过XRD和TEM对产物进行的观察表明，在酸性条件下，向溶液中添加一定量的Bi^3 ，产物的晶型由α型向γ型转化，产物形貌由针状、丝状向颗粒状转变。     

用φ20mm离心萃取器两步法制取高纯钇

本文研究了中钇富镧稀土的氧化物溶液在环烷酸中的萃取行为，测定了镧钇组成、温度变化与分离系数的关系；在Ｐ＿（５０７）体系中研究了ｐＨ值与分配比的关系；提出用环烷酸、Ｐ＿（５０７）两种萃取剂制备高纯钇的工艺流程。用８４台φ２０ｍｍ离心萃取器进行了一个月的台架试验，结果证明两种萃取剂有很好的互补性，在满足钇的纯度要求下有较高收率。离心萃取器具有易分相、体系存留量少、液流密闭性好等优点，它更适宜于粘度大、级数多、产品纯度要求高的体系。     

Full scale thermal testing of latent heat storage in wallboard

Full scale thermal storage tests were conducted in a room lined with PCM wallboard having latent heat storage capacity. The results were compared with those obtained from tests conducted in a similar room lined with ordinary wallboard. The research showed that PCM wallboard can function efficiently as a thermal storage medium which can be applied to peak load shifting, improved use of waste and solar heat as well as more efficient operation of heating and cooling equipment.     

Encapsulation of PV modules using ethylene vinyl acetate copolymer as a pottant: A critical review

The primary purpose of this work is to review the literature about what is and is not known about using ethylene vinyl acetate (EVA0 copolymer as the encapsulant (or pottant) material in photovoltaic (PV) modules. Secondary purposes include elucidating the complexity of the encapsulation problem, providing an overview about encapsulation of PV cells and modules, providing a historical overview of the relevant research and development on EVA, summarizing performance losses reported for PV systems deployed since ca. 1981, and summarizing the general problems of polymer stability in a solar environment. We also provide a critical review of aspects of reported work for cases that we believe are important.Failure modes resolved in the early work to establish reliability of deployed modules and the purposes and properties of pottants, are summarized. Typical performance losses in large field-deployed, large-scale systems ranging from 1% to 10% per year are given quantitatively, and qualitative reports of EVA discoloration are summarized with respect to ultraviolet (UV), world-wide location and site dependence.The general stability of polymers and their desirable bulk properties for solar utilization are given. The stabilization formulation for EVA, its effectiveness, and changes in it during degradation are discussed. The degradation mechanisms for the base resin, e.g., unstabilized Elvax 150^TM, and stabilized EVA are indicated for literature dating to the early 1950s, and the role played by unsaturated chromophores is indicated. The limited number of studies relating discoloration and PV cell efficiency are summarized.Observed degradation of EVA or the unstabilized base resin in the laboratory and examples used to measure the degradation are summarized in sections entitled: (1) thermally-induced degradation; (2) photodegradation and photothermal degradation of EVA in different temperature regimes; (3) photobleaching and photodegradation of the UV absorber and cross-linking agent; (4) acetic acid and metal and metal-oxide catalyzed oxidative degradation; and (5) discolaration and PV cell efficiency losses.Processing effects/influences on EVA stability are discussed in sections entitled: (1) EVA raw materials and extruded, uncured films; (2) thermal encapsulation processes; (3) effects of lamination, curing, and curing peroxide on gel content and chromophores formed; and (4) incomplete shielding of curing-generated chromophores. A summary is given for the limited number of accelerated lifetime testing efforts and examples of erroneous service lifetime predictions for EVA are discussed. The known factors that effect the discoloration rate of several EVA formulations are discussed in which the reduction in rate by using UV-absorbing superstrates is a prime example. A summary is given of what is and is not known about EVA degradation mechanisms, degradation from exposures in field-deployed modeules and/or laboratory testing, and factors that contribute to EVA stability or degradation. Finally, conclusions about using Elvax 150 in EVA formulations are summarized, and future prospects for developing the next-generation pottant for encapsulating PV modules are discussed.     

On integral equation approaches to the mechanics of fibre-crack interaction

The paper examines the problem of a penny-shaped crack which is formed by the development of a crack in both the fibre and the matrix of a composite consisting of an isolated elastic fibre located in an elastic matrix of infinite extent. The composite region is subjected to a uniform strain field in the direction of the fibre. The paper presents two integral-equation based approaches for the analysis of the problem. The first approach considers the formulation of the complete integral equations governing the associated elasticity problem for a two material region. The second approach considers the boundary integral equation formulation of the problem. Both methods entail the numerical solution of the governing integral equations. The solutions to these integral equations are used to evaluate the stress intensity factor at the boundary of the penny-shaped crack.     

离心式永磁直流发电机的设计研究

离心式永磁直流发电机把皮带轮与离心式转子设计为一体,磁场得到了充分利用,降低了成本。本文介绍了电子稳压器通过移相、削波输出电压稳定的直流电,解决了小型农用车的低速照明问题和用电设施需用直流电的问题。     

应用在地下工程施工中的新技术（Ⅱ）

为有效保护地面上的生态环境，开发利用地下空间资源并营建新世纪的地下水城，在新的21世纪里将会建造更多的地下工程以满足人们生产生活的各种需要。文中介绍了地下工程施工中采用的逆作法、盾构法、新奥法、沉管隧道、顶管工程和大型沉井施工新技术，供同行们参考应用。     

化学束外延

本文介绍了化学束外延(CBE)的发明和发展,论述了CBE的原理和设备。文中还介绍了最近提出的一种生长机理。