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.     

PZT铁电薄膜的制备及电学性能研究

使用硝酸锆作锆源的溶胶－凝胶方法制备ＰＺＴ铁电薄膜。他们的电学性能被测试包括电滞回线，电流Ｉ（ｔ）特性，漏电流，矫顽场疲劳和老化。测到的ＰＺＴ薄膜剩余极化８．２μＣ／ｃｍ~２，矫顽场６８ｋＶ／ｃｍ．簿膜的寿命可超过１０~（１１）周期。     

WTG420铁路罐车用钢的组织结构和力学性能分析

分析了ＷＴＧ４２０铁路罐车用钢的组织结构和力学性能。提出了冶炼与轧制的技术关键，其一，添加稀土元素改善钢中夹杂物；其二，采用控轧控冷使铁素体晶粒细化。     

Contributions of source and inhibitory mechanisms to age-related retroactive interference in verbal working memory.

Determining contributions of source-monitoring and inhibitory function to age-related forgetting has been an elusive goal for cognitive theorists. Five studies used a verbal working memory paradigm to examine mechanisms accounting for disproportionate retroactive interference (RI) experienced with adult aging. Participants distinguished studied target-word pairs from interfering pairs that were read aloud. Source-monitoring and inhibitory task components varied through manipulations of response requirements. RI effects were primarily due to source-monitoring failures rather than to inhibitory failures. Removing both source and inhibitory components eliminated age differences in RI. When source monitoring was emphasized, RI continued to be observed in all age groups but disproportionately for older adults. Process dissociation analyses of memory found recollection decreases and familiarity increases consistent with source failures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ZG3Cr13钢经长期时效后组织及硬度的研究

研究了ZG3Cr13钢在550℃～600℃的工作温度区间经2500h长期时效后的硬度及组织的变化。结果表明，在时效1000h内，硬度有明显的下降，之后趋于稳定；组织变化与正常处理后的组织均匀化程度有关，原始组织越均匀组织稳定性和热强性越高。     

Fundamentals of stability testing

The principles on which stability tests are based are reviewed. The need to differentiate between product stability and product-container compatibility is emphasized. Recognition of this distinction is fundamental to the efficient organisation and execution of stability tests.
Attention is also drawn to the desirability of having for every product a release specification with which it must comply when manufactured and a broader check specification with which it must comply throughout its shelf-life.
Test methods and the interpretation of the data accrued throughout a test are also discussed.
It is concluded that stability tests should not be conducted in accordance with a standardized routine pattern but that the objectives of each test should be defined and the test designed to achieve those objectives in the most efficient way.
Les regles fondamentales des essais de stabilite     

évaluation du livre intitulé manuel de gérontologie sociale 2.

Reviews the book, Manuel de gérontologie sociiale 2 by Jean Carette (1992). The Handbook of Social Gerontology 2 constitutes a practical complement of volume 1 which related to the social aspects of ageing and the retirement. Volume 2 relates mainly to the social intervention whose objective is to support the action and the collective mobilization individuals and associations of retirements. Using a 30-year experiment with groups of retirees, either in preparation of retirement, or in the collective action, the author approaches a new ground in gerontology. He proposes a new approach--social gerontology, (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

多级泵站老化的模糊评价模式

多级泵站是一个包括各级泵站及泵站内各种设施的复杂系统，系统内各个泵站的老化直接影响整个泵站系统的正常运行，采用单元化方法将多级泵站系统单元伦，引和泵站老化评价指标，建立了多级泵站老化的模糊评价模式，并对甘肃省景泰高扬程提水灌区多级泵站系统进行分析，提出了评价多级泵站老化程度的排序方法。     

铝活塞余热淬火和自然时效的应用研究

图 1所示的活塞试件 ,在开型时间为 5 0s～ 5 5s时 ,其表面温度为 (4 90± 5 )℃ ,可满足淬火要求。自然时效时间为 2 4天时 ,其机械性能可达到国标技术要求。这种新工艺有明显的经济效益。     

某军用直流电源的RET方法研究

可靠性强化试验(RET)是一种新兴的试验技术,它使用在产品的设计阶段,用于快速暴露产品的缺陷和薄弱环节。以某军用直流电源为例介绍了可靠性试验方法,并对可靠性强化试验方法的优越性进行了讨论。