Educational Satellites: A Goal or Gaol?

Human and social problems, as well as benefits are often a consequence of technological advances. There is no reason to believe that the application of satellites to education will not create similar consequences. In this paper, several issues of significance in the wide-spread application and use of satellites in education are discussed, including the implications for education and cultural change; the organizational problems in operating a major satellite-based educational system; financing the activities; and the need to aggregate the market in order to amortize large investments for equipment and production, while maintaining a diversity of educational offerings to satisfy local needs. In one sense, the basic difficulty in applying satellites to education is how to develop and apply techniques that can be highly effective, but which are economical only when applied on a mass basis, to insure that there is enough flexibility and variety so that education can be responsive to local needs and desires. The task is to apply satellites to education in order to improve the quality of education, reduce its cost, increase the availability of educational opportunity, and create possibilities for additional choice, yet do so without creating new problems that outweigh existing ones. This is the challenge to those who are making decisions about applying satellites to education that is raised in this paper.     

Linear and nonlinear system identification of autonomic heart-ratemodulation

The authors' findings show that system identification provides a useful, noninvasive, and quantitative means for evaluating cardiovascular regulatory mechanisms. With combinations of linear and nonlinear identification, new insights about the cardiovascular regulatory dynamics were obtained. System identification provides a new way of studying and monitoring cardiovascular function. Instead of just studying the signals generated by the cardiovascular regulatory system, the signals are analyzed to characterize quantitatively the mechanisms that generate them. System identification is a type of “inverse modeling”in which the physiologic signals are used to create a model of cardiovascular regulation for the specific individual from whom the data are obtained. As such, system identification would appear to be a desirable means for evaluating effects of physiologic alterations resulting from pharmacological interventions, changes in environment such as changes in gravitational field, physiologic stresses such as hypoxia and exercise, and disease processes. System identification may also prove to be an attractive means to study closed-loop regulation in other physiologic systems, ranging in size from biochemical pathways to intact multi-organ systems     

Real-Time Fluorescence-Enhanced Imaging as an Aid to Surgery in Ovarian Cancer

Epithelial ovarian cancer has the highest mortality among all gynecologic cancers. Due to the nonspecific nature of its symptoms, most women with ovarian cancer present with advanced stage disease, resulting in a poor overall prognosis. Surgical tumor debulking is one of the most effective interventions to improve the outcome for these patients. However, reducing the amount of residual tumor to microscopic levels is often complicated by the small size of the implants and poor visual contrast between small tumor implants and normal tissue under white light conditions found in most operating rooms. Therefore, one proposed method to improve the resection of metastatic ovarian cancer is to apply tumor-targeted optical fluorophores that could identify sites of metastasis with high sensitivity and specificity, providing the surgeon with an intraoperative guide to tumor location. Herein, we describe a novel method of identifying ovarian cancer metastases using fluorescent tagging and a real-time fluorescence camera that allows the resection of metastatic disease that would otherwise not be visible to the surgeon.     

BSEE Curricula: The Electric Utility Engineer Looks Back

Under the aegis of the Engineering Education and Human Resources Task Force of the Edison Electric Institute a questionnaire was circulated to investor-owned utilities throughout the nation. The essential aims of the questionnaire were to seek answers to and provide background information on questions relating to BSEE curricula followed by engineers employed within the electric-utility industry for about five years. Responses from approximately 450 engineers working within the electric utility industry were received. The thirteen multipart questions which constituted the questionnaire provide background information, against which the suggested curriculum changes deemed most desirable by respondents can be examined. There is clear indication of course-areas which need to be developed if they are to meet the needs of electric-utility based engineers.     

Assessment of myocardial perfusion using contrast-enhanced MR imaging: Current status and future developments

Excellent inherent tissue contrast is one of the great promises of clinical magnetic resonance (MR) imaging, but functional information is relatively limited. However, MR imaging complemented by the administration of contrast agents can provide such functional assessment. The perfusion status of the myocardium is one of the most important functional information in cardiovascular imaging. Because the clinical acceptance of a contrast agent is measured by its ability to improve patient outcome and to guide therapy, it is unlikely that detection of myocardial infarction, the final stage of ischemic heart disease, should be the target for contrast media development. It would obviously be better if occult regional myocardial perfusion deficits could be reliably detected. The current article was prepared to help the clinical radiologist to keep pace with new strategies for myocardial enhancement and their potential clinical applicability for detection of early perfusion deficits. Several techniques for noninvasive measurement of myocardial perfusion are currently evolving which have the potential to be introduced into routine MR imaging. Most investigators favor a first-pass analysis of the contrast agent bolus through the myocardium using ultrafast sequences. However, such a technique may require clinical introduction of a blood pool agent. There are good resons to favorT ₁-weighted sequences over susceptibility imaging in such first-pass studies. In the future, assessment of myocardial perfusion status using contrast-enhanced MR imaging may be done producing perfusion maps with high spatial resolution (e.g., 256×128), with sequences available on most scanners without special hardware requirements (e.g., IR-Turboflash, keyhole imaging), and requiring only a short period of time for examination (≈3 min).     

山区城市电力需求预测分析

本文介绍了电力需求预测常用的几种方法,对其各自的优缺点和适用范围进行了分析比较,结合韶关地区的电力需求数据,指出山区市在电力需求预测方面应采取的思路和方法。     

Shake it up

Since its launch in 2001, the DTI-funded Process Industries Centre for Manufacturing Excellence (PICME) has served manufacturing clients from all walks of the process sector - chemicals, polymers, pharmaceuticals, fine chemicals and agrochemicals. All UK-based process manufacturers qualify and can apply to benefit from the redcar-based industry forum's diagnostic and performance measuring/benchmarking activities that aim to save manufacturers money in areas such as stock management, machine utilisation, lead-times, process variability and supply chain efficiencies. According to an expert, waste minimisation or elimination should be the driving philosophy behind most manufacturing and operations improvement; not only in terms of wasted end-product, but also in terms of other wasted inputs to the operation. PICME uses tried and tested systems to analyse for all types of waste including the traditional seven as well as a few other categories in which experience suggest needs special focus in this sector including the waste of good ideas which are essential to innovation. This paper discusses how PICME helped process industries strive for process excellence.     

基于泛在智能互动的客户办电服务新探索

目前电力公司客户办电服务存在不足,客户服务体验有待提升,而办电服务提升是国家电网公司当前重点工作任务之一。在国网政策以及泛在电力物联网建设的背景下,结合泛在电力物联网的理念,以目前最先进的技术、设备为基础,围绕办电服务全过程,提出构建智能互动办电服务体系,覆盖线上、线下客户办电业务,从根本上提升服务的智能互动化水平、办电效率,提升客户办电服务体验。     

Are "Engineering" Graduates Prepared to Meet Their Employers?

The most important aspect of an educational program is to evaluate its merits in meeting the needs and concerns of those who hire its product, the graduates. The world of work is discussed and analyzed from varied viewpoints; individual wants and needs, how this relates to the employer-employee relationship, the attributes that most employers are seeking, and the specifi'c concems of industry in the technical spectrum. There are two sides to the work world-an employee is concerned about what he has to gain by considering a choice of employment: remuneration rewards, relevant work, challenging work, respect as an individual, social satisfaction, and the opportunity for career advancement; the employer will be concerned about what's in it for them should they hire the employee: basic skills, cooperative attitude, ability to communicate, loyalty, integrity, motivation, initiative, performance, and appropriate appearance. The "engineering" curriculum to meet these employee-employer needs is discussed and the reader is thus queried, depending upon their own frame of reference, to decide whether or not "engineers" are prepared to meet their employers.     

NPC三电平变换器中点电压控制方法综述

中点箝位型(NPC)三电平拓扑是目前最常用的一种高压大功率多电平拓扑。在NPC三电平变换器的控制中,中点电压波动问题是一个直接关系到系统安全性与输出性能的重要问题,需要妥善解决。目前存在许多种可以抑制NPC变换器中点电压波动的控制方法,这里针对NPC三电平变换器,对其中点电压波动进行了分类并分析了其产生原因。归纳总结了常见的NPC三电平变换器中点电压控制方法,尤其对中点电压的软件控制算法进行了细致的分类和对比分析。     

Educational Technology Applied to an Electrical Engineering Laboratory Program

In the fall of 1969 a systematic reorganization of the EE laboratory program was begun at Purdue University. The reorganization was approached using an educational system model which recognized the needs for: clear statements of instructional objectives, mechanisms for information transfer, opportunities to practice, and apply new skills, the personal dimension of education and evaluation procedures. A second educational model, essentially orthogonal to the one above, based on Bloom's taxonomy of educational objectives was used to plan the degree to which various skills and activities should be stressed in each course. The educational methodologies used in developing the program and the end product of this effort are described.     

135MW全浸式蒸发冷却电机定子的绝缘结构

为了将拥有我国自主知识产权的蒸发冷却技术应用于高电压、大容量的汽轮发电机,并作为主力机组,需要解决定子绝缘结构的合理设计问题。全浸式蒸发冷却定子需要利用蒸发冷却介质的绝缘性能,大幅度减薄定子主绝缘的厚度,实现冷却与绝缘的双重功效。为此运用有限元数值仿真理论,首先详细计算并分析了该冷却方式下的定子绝缘结构内的电场与温度场,总结其分布规律与特点,证明了135MW全浸式蒸发冷却汽轮发电机主绝缘减薄的的合理性与可能性。这些仿真计算的结果通过了试验模型的检验,是合理可靠的,在此基础上提出定子主绝缘厚度的合理设计值以及对应的电流密度。研究结果值得国内制造业的借鉴。     

基于步进电机的微量计量泵控制系统的研究与实现

针对传统微量计量泵控制精度低、难以满足大规模生产工艺流程控制的自动化要求等现状,采用步进电机技术,以THB6064H步进电机驱动芯片为核心,开发了一种通过改变冲程频率来实现液体计量的微量计量泵控制系统。该系统与上位机通过串口进行通信,使其更方便地应用到多种场合。经测试证明该控制系统具有成本低、功能全面、输入数据方便等优点。     

对应用暂态能量函数法分析电力系统暂态稳定性的评价

基于李雅普诺夫稳定理论,对用于电力系统暂态稳定分析的暂态能量函数法进行了分析,认为可定量分析和快速性是其独特优势,不可靠性是其局限性,提出了暂态能量函数法用于非自治系统所必须满足的条件,包括用临界轨迹确定临界能量,以及用临界轨迹得到的切除时间确定故障清除后的稳定平衡点等,尽管目前暂态能量函数法只作为电力系统暂态稳定分析的辅助工具,但如何提高它的可靠性并将其应用到非自治系统仍是有待深入研究的课题。     

Departmental intranets

Many people use the Web everyday in their jobs. Excluding those whose jobs are to design, implement and maintain a Web infrastructure, most are looking for information. The Web provides an excellent medium for this information exchange and data retrieval. But, the entire World Wide Web (WWW) cannot serve the microscopic tailored needs of an individual's work project. What's more, a large corporation's intranet cannot serve those specific employee's needs well either. This is where a departmental intranet comes into play. A low-cost intranet can effectively serve the data archiving, retrieval and information exchange needs for any department. Additionally, an intranet caches data locally so workers can spend their time producing instead of waiting for data. There are many ways to set up an intranet. Hundreds of commercial solutions with dedicated servers, software and specially trained administrators exist, but all at a very high cost. Besides that, issues such as man-hours, capital expenses, urgency and privacy have to be examined. The solution discussed makes tradeoffs between man-hours and capital to install a freeware-based Web server into an existing infrastructure     

Equivalent circuit of transformers with control of voltage and phase angle

This paper presents a methodology aimed at obtaining the equivalent circuit of regulating transformers. This aspect is insufficiently treated in most current textbooks in which the equivalent circuit of a tapped transformer is not well justified. The document shows how to obtain the equivalent circuit of a regulating transformer with control of voltage magnitude and phase angle, and how to apply it using either physical quantities or per unit (pu) quantities. The resulting equivalent circuit is adequate for steady-state calculations under balanced conditions and neglects transformer core parameters. The usage of per unit values can be made by selecting the base quantities in an arbitrary manner, which is an obvious advantage when the turns ratio must be estimated.     

The high-frequency phenomenon of copper clad aluminum wires which are lower the alternating current resistance than copper solid wires,and the application of copper clad aluminum wires to the electrical equipment

The paper is proposed approximate formulas of the ac resistance of lead wires and coils which made by using copper clad aluminum (CCA) wires. There are the frequency range that the ac resistance of CCA wires is lower than it of cupper solid wires for lead wires and coils of an electrical equipment. It is shown that the application of CCA wires is economical as comparing with copper solid wires, if the design is due to successful calculation in the electrical equipment. The measured resistance is compared with the formula. CCA wires is an example of multiple conductors which shall be expected to apply in future.     

电网信号谐波分析算法计算性能比较研究

电网信号谐波分析算法种类多,适用于不同的负荷场景,但它们的性能优劣,目前仍没有一个统一的性能评价指标体系,致使很多用户无法根据自己的特定需求,更合理、快速地选择出最适用的谐波分析算法。针对于此,文中比较研究了621种电网信号谐波分析算法的计算性能。具体地,对众多窗函数,按频域特性的不同进行了分类;并根据计算原理,将电网信号谐波分析算法分成了加窗FFT插值、加窗FFT和谐波分组算法等三大类,进而比较分析了这些算法的计算准确度和计算的硬软件开销等性能;探究了非整周期采样和噪声等对算法计算准确度的影响;基于对供电系统电压、电弧炉电流以及风电机组电流等典型信号的分析计算结果,选取出了推荐算法;最后,还对稳态谐波分析算法在被测信号发生典型动态变化下的计算性能进行了测试。所得结论对不同电力用户依据自己的特定需求、选用合适的谐波分析算法以及开展相关研究等方面,可提供有说服力的指导和帮助。     

基于J2EE技术的网上用电申请系统的设计与实现

随着社会信息化程度的不断提高,为用电客户提供方便快捷的网上用电申请服务成为供电企业为客户提供优质服务的新手段。根据网上用电申请系统的功能和性能需求,提出在J2EE（Java 2 Enterprise Edition）技术框架下的网上用电申请系统设计和软件实现手段,分析实现过程中使用的涉及J2EE技术框架的JSP技术、Hibernate技术以及其他相关技术。     

设备状态监测系统的DL/T860建模及智能化设计

状态监测是获取设备运行状态的技术手段,是检修与运维的重要信息来源。根据面向智能电网的设备状态监测系统智能化的建设及改造需求,给出了基于DL/T860标准通信规约的从变电子站到主站的全面设计方案,解决了IED的标准化、互操作性和互换性问题,实现了信息共享,为生产管理、状态检修、智能电网决策分析提供所需要的数据,为实用化的状态监测技术应用、选型积累经验。