冷却剂参数对铣槽喷管低周疲劳寿命的影响

采用有限体积流固耦合计算方法、非线性有限元热结构耦合分析方法和局部应变法研究大面积比铣槽喷管三维再生冷却槽道在循环工作条件下的热结构变形与低周疲劳寿命,并对比分析了冷却剂质量流量与入口温度对铣槽喷管疲劳使用寿命的影响。计算结果表明,铣槽喷管热结构响应呈现复杂的三维效应,应变较大位置主要分布在与肋连接的内衬区域,喷管中部的残余应变量最大;冷却槽道低周疲劳寿命分布和热结构响应基本一致,最小寿命位于喷管中部与肋相连的内衬区域燃气侧;随冷却剂质量流量增加,铣槽喷管低周疲劳寿命不断提高;随冷却剂入口温度增加喷管尾部低周疲劳寿命值不断降低,而喷管中前部的低周疲劳寿命值却不断提高,当冷却剂入口温度为280K左右时,本文的铣槽喷管总体使用寿命达到最大。      

发动机燃烧室内壁材料热环境的气动热试验模拟技术研究

利用超声速矩形湍流导管和等离子电弧加热器模拟了发动机燃烧室内流和高超声速飞行器外壁面外流热环境,进行了平板表面冷壁热流测量和燃烧室内壁材料考核试验。结果表明:由于辐射换热的影响,在选取的两个典型来流条件下,发动机燃烧室内流热环境下的冷壁热流比外流热环境下的高出21%和40%,但是冷壁热流的增量基本相当,约为0.70~0.80MW/m²。随着冷壁热流的增加,辐射换热产生的热流增量的影响力会逐渐减小。材料考核时,相同配方的C/SiC复合材料在内流热环境下的表面温度高出约400℃,背面温度高出约90℃,这种差异对于发动机燃烧室内壁面材料考核至关重要,必须在材料考核试验中加以考虑。      

夏热冬暖地区高校图书馆室内热环境测试与分析

以广西大学图书馆作为研究对象,在室内选取15个测点进行热环境测试,测试内容包括室内空气温度、湿度、气流速度以及黑球温度和建筑围护结构表面辐射温度。结合相关的研究资料和实测数据对其馆舍热环境进行分析,为认识夏热冬暖地区图书馆馆舍热环境特征、营造室内舒适环境的节能改造技术研究等提供依据。     

高温下预应力混凝土板温度场及力学性能的数值分析

对高温（火灾）下预应力混凝土简支板利用Ansys数值模拟板的温度场及应变,与已有试验对比得出高温下预应力构件温度场及力学性能通过Ansys软件有限元分析的可行性;对一预应力混凝土板进行数值模拟,得出板在单面受火过程中温度场变化的规律及其跨中应变随时间一温度的变化。     

科学数据在地震短临预报中的科学利用

文章在对科学利用卫星遥感热红外数据开展临震预报现状分析的基础上,阐明卫星热红外亮温异常的基本原理,并建立临震地震遥感信息模型。通过20多年试验性预报实践,说明亮温异常数据在地震短期和临震预测中具有重要作用,卫星遥感热红外临震预报技术具有实际应用前景,并提出科学数据只有通过科学地开发与利用。才能造福于人类。     

科学数据在地震短临预报中的科学利用

文章在对科学利用卫星遥感热红外数据开展临震预报现状分析的基础上,阐明卫星热红外亮温异常的基本原理,并建立临震地震遥感信息模型.通过20多年试验性预报实践,说明亮温异常数据在地震短期和临震预测中具有重要作用.卫星遥感热红外临震预报技术具有实际应用前景,并提出科学数据只有通过科学地开发与利用,才能造福于人类.     

冲压发动机C/SiC喷管承压失效研究

新型三维编织碳/碳化硅复合材料存在较强的各向异性,而各个方向的性能数据积累不足,复合材料的强度计算方法尚不完善,为了发现新型三维编织碳/碳化硅复合材料在冲压发动机喷管中应用可能遇到的问题,并找到相应地解决措施,开展了这种复合材料应用于冲压发动机喷管的承压强度计算和承压实验研究。对承压实验中出现的低压破坏情况进行了分析,分析了低压破裂的原因,提出了改进措施。分析结果表明:C/SiC喷管喉部密度较低,导致强度较低,承载能力下降,是首次强度验证实验过程中该局部破坏的原因;为提高喷管强度,需要通过其形状设计并控制沉积流场,保证其喉部的沉积密度达到1.9g/cm³以上。对改进后的喷管进行了实验验证,实验结果与计算结果基本一致,满足要求。因此,在实际应用中应对喷管喉部和纵向密度的分布进行工业CT无损检测,确保喷管密度的分布均匀。      

基于虚拟仪器技术的焊接预热温控系统设计

基于虚拟仪器技术,在LabVIEW中设计了一种焊接预热温控系统,实现了温度数据的采集监视和存储回放,并提供可靠的报警功能,具有加热迅速均匀、热惯性小、温控精确、安全可靠等优点,为传统梯度表式的手工温控系统提供了理想的替代方案。通过模块化的软硬件扩展能方便的对系统进行升级,值得在造船焊接等金属热处理领域推广应用。     

纳米材料改性沥青热反射性能试验研究

基于传热学和材料学原理,进行了改性沥青中掺入高折光指数的纳米填料TiO2、SiO2的热反射试验,以提高沥青混凝土的反射率,降低吸收率及路面温度。按改性沥青：2%、4%、6%线型/星型SBS＋基质沥青,2%、4%、6%TiO2/SiO2＋基质沥青,6%线型SBS＋2%,4%,6%TiO2＋基质沥青的配比制作试样,利用实验室简易法测定各种类型沥青的热反射效果。试验结果表明,线型/星型SBS对沥青热反射的影响不大,折光指数高的纳米材料TiO2及SiO2能明显地提高改性沥青的反射率;与基质沥青相比,掺加6%线型SBS和6%TiO2的改性沥青表面温度减低超过5,可以有效地提高沥青的反射率,从而降低了路面温度及带来的温度应力破坏,有一定的应用前景。     

超长框架结构温度荷载下非线性分析

针对目前超长框架结构温度应力分析多集中于混凝土的线弹性阶段的情况,借助于通用有限元软件Ansys,采用混凝土“分布式”裂缝模型,对一个典型的超长框架结构在承受渐变温度荷载下的柱顶位移及应力变化情况进行了数值模拟。分析表明：温度应力是引起混凝土板开裂的重要因素并且具有明显的非线性;混凝土“分布式”裂缝模型在模拟较长框架结构的整体响应时,能够满足一般的计算精度。     

British Writings on Romania: From Travel Accounts to Studies

This article surveys a sample of sources of the information about Romania available to British readers in nineteenth century British newspapers and periodicals. It traces first contacts between the Romanian lands and Britain after the union of the principalities of Wallachia and Moldavia in 1859, then after their independence from the Ottoman Empire. The article highlights an increased Romanian interest in British periodicals, which reported and reviewed Romanian literature and scholarship. The article concludes that nineteenth century British newspapers and periodicals offer a great variety and wealth of new material previously unavailable or unknown to researchers. It also states that only a portion of a large quantity of this material has been indexed and is therefore available via the bibliographic sources mentioned in the article. The author argues for the need of a new and updated British-Romanian bibliography, which can draw on new online resources offering access to thousands of new newspapers and periodical records.     

Slavic Approval Plans: What Works and What Doesn't

ABSTRACT

The paper looks at library approval plans for material published in Slavic, East European, and Eurasian countries from the selector's point of view. Reasons why a selector would or would not want one are examined. Success with approval plans requires monitoring receipts, as well as good and ongoing communication among the selector, the acquistions department, and the vendor. A preliminary list of vendors offering approval plans for the countries of the region appears in the appendix.     

由“资源集聚”向“需求导向”转变——对武汉科技信息服务平台建设的思考

为进一步提升武汉科技信息共享服务平台使用效率,本文从平台资源建设、资源应用、供需对接方式和供需特点等方面分析了武汉科技信息资源服务现状;基于需求和利用的角度,结合平台管理实践和走访用户、问卷调查等研究方法,从信息资源需求主体和平台自身建设管理两个维度,找出制约科技资源供需对接的主要因素;以市场化和制度化为创新理念,从政策创新、机制创新、市场化服务、环境营造、人才培养等方面提出平台建设由“资源集聚”向“需求导向”转变的对策建议.     

Politicking for the Public Library

ABSTRACT

In today's current political environment raising support for millage renewals, bond campaigns or even millage continuations for public libraries is affected by national politics, and a tendency towards tax aversion on principle across the country. The lessons we can learn from the governing boards of small and rural public libraries are worth raising up to a greater national consciousness. Board governance, community consciousness, and facilities management are clear and logical tools that elected boards of public libraries can use to politick for support of libraries.     

Architectures of Knowledge and Literary Tradition: A History of the Almanac in Croatia

ABSTRACT

The history of the almanac in Croatia is reconstructed through primary research in bibliographic and archival sources. The almanac is a vehicle for knowledge communication in informal contexts, engaging both oral tradition and literary forms traceable to medieval literacy and ways of structuring knowledge. The history of the almanac in Croatia reflects the changing context of the book trade, literacy, and the evolution of language. Four main stages are identified: (1) the beginning of the annual almanac in the seventeenth century; astrological almanacs reflecting the sensibility of the Baroque period; (2) the Enlightenment's stimulation of almanac publishing in the spirit of contemporary secular reforms in agriculture and education; (3) nineteenth-and twentieth-century almanac trade, showing complex and overlapping networks for the production, distribution and appropriation of printed almanacs;(4) roughly the end of World War II, when the almanac slowly moved out of the role of a popular mass medium and into specialized niches represented by regional, diaspora, and religious almanacs.     

基于文献时间特征的学科主题演化分析方法研究 ——以图书情报学领域为例

在分析文献在不同研究阶段用词时间特征的倾向性基础上,提出一种基于主题模型的研究发展阶段识别方法。重点阐述该方法的构建过程,包括时间特征抽取、发展阶段界定、主题冷热变化分析等步骤。为验证该方法的有效性,针对词频统计法和主题模型方法在主题演化分析中的效果进行比较分析。结果表明,该方法能在识别主题热点和发展趋势的同时,有效地区分不同主题所反映的研究发展阶段。     

How Digital Content Resellers are Impacting Trade Book Publishing

Some key questions for publishers in today’s market are: Could Amazon’s recent merger and acquisitions strategy create a disruptive or paradigm shifting business model in the publishing industry? Do their recent actions post mergers and acquisitions illustrate a predicable pattern of behaviour that publishers can strategize around? This paper will explore these questions and look at some of the possible reasons behind Amazon’s business practices and the possible consequences to publishers.     

Germany's New Culture of Welcome—Our Libraries are an Essential Part of it

ABSTRACT

German authorities are expecting more than 1 million refugees by the end of 2015. These people come to Germany to seek protection and assistance and to build a new life, therefore it is important to welcome them and to assist them in their integration as soon as possible. This situation creates a versatile and perfectly fitting opportunity for cultural and educational programs, including libraries, which can play a vital role in this integration process. The key to integration is the knowledge of the German language, and the most important challenge now is to teach the necessary language skills to as many asylum-seekers as possible.     

Syndicating Rich Bibliographic Metadata Using MODS and RSS

Abstract

Many libraries use RSS to syndicate information about their collections to users. A survey of 65 academic libraries revealed their most common use for RSS is to disseminate information about library holdings, such as lists of new acquisitions. Even though typical RSS feeds are ill suited to the task of carrying rich bibliographic metadata, great potential exists for developing applications that can exploit metadata exposed to Web services via RSS. Using the MODS metadata format, entire catalog records can be seamlessly embedded in RSS 2.0 feeds. Existing tools, such as Library of Congress Java toolkits and XSLT stylesheets, can facilitate this process, while a new XSLT stylesheet may be used to create the RSS feeds complete with MODS records. As an example of the added functionality these MODS/RSS feeds can offer, records from a MODS-enriched RSS feed can be ingested into a non-RSS application such as Zotero. As more emerging library technologies use Web services architectures to handle data objects, the ability to syndicate catalog records will become more critical to providing innovative library Web services.     

Selling Women on PDAs from “Simply Palm” to “Audrey”: How Moore's Law Met Parkinson's Law in the Kitchen

This essay investigates key moments in the history of personal digital assistant (PDA) marketing to women. Analyzing promotional texts for three PDAs that received considerable press coverage from 1999 to 2001, this essay explores the cultural significance of the convergence of anxieties about women's place in the gendered division of labor with the computer industry's changing marketing imperatives. Drawing on an array of promotional texts, including news articles, press releases, promotional Web sites, and ads appearing in newspapers and magazines, this paper tells the story of how the computer industry aimed to sell smaller, faster computing devices to women while promising to mediate and thus reproduce women's overwork as paid and familial laborers. After experimenting with the PDA as a sexy fashionable gadget for working women, marketers approached women as mothers with “Audrey,” an Internet appliance designed for the kitchen.