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1.
以比亚迪E6、荣威E50、江淮iev3 为研究对象,利用CRUISE仿真分析NEDC_LOW和上海两种行驶工 况下燃料消耗经济性,构建基于购置成本和使用成本的纯电动汽车消费者拥有成本模型,分析纯电动汽车的市场竞争 力,并与传统汽油车进行比较。  相似文献   
2.
为了改进流量可调燃气发生器的调节精度,引入燃气发生器压力闭环控制,针对流量可调燃气发生器压力闭环控制特点,在压力闭环中引入了模糊积分控制,此控制算法响应速度快,超调量较小,不同工况及长时间工作下系统仍然有较好的动态特性。   相似文献   
3.
The author discusses “Text a Librarian,” a short message service-to-email service provided via Upside Wireless, Inc., a Canadian telecommunications provider. Any user of the University of Virginia Library who has a cell phone and text messaging capability can send a text message to a local phone number provided by Upside Wireless. Upside's “virtual SMS channel,” which forwards the message to the Library's reference e-mail account. Librarians then respond to the query with an e-mail message that the user receives as a text message on his or her cell phone. This article describes the process by which a library developed the idea for the service and decided to contract with Upside, as well as staffing for the service and the challenges, successes, and possible new directions. A brief survey of the SMS reference landscape is included.  相似文献   
4.
针对燃烧加热地面试验设备存在的工质污染问题,采用数值模拟方法研究了燃烧加热污染空气对氢燃料超燃冲压发动机性能的影响。以飞行马赫数Ma=6.5,当量油气比ER=0.6为计算基准状态,分别对纯净空气和污染空气来流下氢燃料超燃冲压发动机的整机流场和性能进行了对比计算分析。燃烧化学反应模拟采用了改进的H2/O2七组分八方程模型,湍流模型为标准的 k-ε模型,并采用直连式燃烧室试验数据进行了数值方法的验证。研究结果表明:(1)相对于纯净空气来流,污染空气来流下的超燃冲压发动机推力和比冲均有所下降。(2)采用酒精燃烧加热器的前提下,来流参数匹配静温、静压、马赫数时,发动机性能与纯净空气来流下的结果最为接近,而匹配总温、总压、马赫数时相差最大。(3)来流参数匹配总焓、静压、马赫数的前提下,采用氢燃烧加热器时发动机性能与纯净空气来流下的结果最为接近,而采用甲烷燃烧加热器时相差最大。   相似文献   
5.
周仁惠 《编辑学报》2008,20(3):257-259
从3G时代手机媒体的特点出发,分析其对读者的阅读行为与习惯的影响,提出了3G时代期刊界应彻底转变观念,处理好纸介质出版与数字出版、一般的数字出版与手机媒体数字出版的关系,开展传统出版与手机传媒间的整合,实现资源共享;建设各个类型的数据库,培育发展手机媒体的数字内容业务;创新商业模式,向特定读者提供个性化服务;加强内容资源的建设,提升期刊市场竞争力:为未来的期刊出版提供了新的思路。  相似文献   
6.
顾震宇  路炜 《图书馆杂志》2006,25(11):40-44
本文基于Dialog联机检索,以德温特世界专利索引数据库和专利引文索引数据库为数据源,对质子交换膜(PEM)燃料电池行业进行了专利分析研究。作者用实例说明了利用各种Dialog高级检索指令实现行业专利分析的技巧。通过分析研究,发现了PEM燃料电池行业的领先企业、技术领军人物、产业发展前景、全球技术/市场布局、关键技术、研发热点等。研究表明,Dialog?联机检索在行业专利分析中是一种有效的工具。  相似文献   
7.
网络广告走到了十字路口   总被引:1,自引:0,他引:1  
本文针对中国网络广告中存在的突出问题,如强迫式广告过多,缺乏创意等;提出了相应的对策,并对手机媒体广告作了探讨。  相似文献   
8.
Microfibril angle (MFA) – the orientation of cellulose fibres in the S2 layer of the secondary cell wall – is a key determinant of the stiffness and strength of timber. The microfibril angle depends on the way in which the timber was grown and its position within the tree. Microfibril angle can be measured by X-ray diffraction and other methods, but the methods in current use are slow or require advanced instrumentation. The aim of this study was to explore the use of polarised Fourier transform infrared (FTIR) microscopy as a relatively fast and inexpensive method for measuring MFA in historic Scots pine (Pinus sylvestris L.). The FTIR measurements were calibrated against X-ray measurements of MFA in modern Scots pine. We observed a wide range in MFA values and a radial pattern of MFA similar to modern Scots pine in undecayed Scots pine heartwood from sixteenth and seventeenth century beams in Scottish secular buildings. The density of the heartwood was also similar to modern plantation-grown Scots pine despite the much slower growth rate recorded in the ring widths of the historic timber. The sapwood, which had been attacked by both insect pests and fungi, showed an erratic reduction in density and a large increase in MFA compared to the modern material. The increased sapwood MFA was attributed to selective destruction of the S2 layer of the wood cell walls by fungal decay. Using MFA measurements in conjunction with density offers the possibility to estimate the mechanical properties of sound historic pine timber, to detect fungal decay more sensitively than by density alone, and to distinguish between pest and fungal attack in a way that relates directly to the remaining mechanical performance of the timber.  相似文献   
9.
In the early months of 1947, as it sought to save power during an acute fuel crisis, Clement Attlee's Labour government suspended the publication of all British periodicals for a period of two weeks. This would have been a bold step for any government, let alone one which had as uncomfortable a relationship with the press as Attlee's did, and, at the time, the press was not slow to suggest that the suspension was motivated as much by political factors as it was by a desire to conserve fuel. This article examines the implementation and nature of the suspension, exploring the tensions it generated and asking whether the government's actions can be described—as they were by some contemporary observers—as a deliberate act of suppression.  相似文献   
10.
No Phone Zone     
Abstract

This article reports the results of a survey of cell phone policies in university libraries conducted over a three-month period in 2005. The authors sought information about the libraries' problems regarding cell phone use and attendant noise by students and other library users. The authors began with an 18-question survey of one hundred libraries, with at least one library from every state. When the response was low, the authors expanded their research by looking at every library Web page that had the word “University” in its title. Finally, they contacted several larger libraries that had policies banning cell phone use altogether to see whether they worked. Most respondents found cell phone noise a problem. Most respondents indicated that public service staff and security officers enforced the policies; comments from the original survey were insightful concerning compliance solutions.  相似文献   
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