A critical assessment of the US code for lightning protection ofboats

It is argued that the US code for lightning protection of boats is seriously inadequate. Downconductor conductance should be specified as that of #4 gauge copper rather than the #8 gauge presently specified in order to minimize the risk of overheating and melting. The 1-ft² ground plate is shown to be inadequate to prevent side flashes in fresh water. The magnitude of the potential gradients involved is 2 orders of magnitude larger than the breakdown value if the effect of breakdown in the water is ignored. In salt water, a 1-ft² ground plate is adequate. The concept of a cone of protection with a 90° apex angle is not applicable to the attractive effect of sailboat masts because it underestimates the probability of strike occurrence by an order of magnitude     

Change,the Need for Security

如何开发新的信息化资源，架构新的安全保障体系？如何整合和提升原有的信息化资源？以及如何节能减排将呈现强劲的发展势头。变革，如今不仅仅意味着刺激全球经济回暖，也在为IT和IT安全领域注入新的期待和信心。     

Need for data-driven instruction of engineering English

The author emphasizes the role of data-driven corpus-based methodology that promotes the study of natural language on examples of real life language use in teaching English for Specific Purposes (ESP), such as Engineering English. This approach can improve the way Engineering English is taught and add more creativity in ESP classes. In particular, the author demonstrates how vocabulary teaching in the ESP context can benefit from a corpus-based approach. She addresses the issue of technical and sub-/nontechnical vocabulary with characteristic examples from teaching situations in Southeast Asia. It is argued that sub-/nontechnical vocabulary should be given more attention in the ESP classrooms than technical vocabulary. Surprisingly, sub-/nontechnical words seem to cause more problems for ESP students specializing in technical fields than technical terms. It is also claimed that the availability of specialist language corpora and computerized text analysis (i.e., concordancing) programs can help learners acquire what D. Bolinger (1976) called "the prefabs of language," or formulaic multiword units (collocations), for technical and nontechnical uses.     

Wireless Landscape – Need for Seamless Connectivity

The unprecedented growth in cellular and wireless technology has brought the tremendous incompatibility and coexistence issues based on access, economic, political and geographical reasons around the globe. The compartmentalization and isolation of standards development based on mobility and coverage requirements have added the incompatibility and interoperability issues even further since they don't exploit the commonality and the issue of coexistence. The universal wireless platform approach with seamless roaming would alleviate the incompatibility, coexistence and roaming issues marring the present generation of cellular and wireless landscape.     

Communicating by Recorded Information--A Need for Changing Technology

If one examines the need for the recording of information, it will emerge that for some classes of information it is essential that it be recorded, whereas for others, it seems only a matter of convenience, convention, or habit. The implications of this statement are discussed in this paper with the aim of determining whether a need exists for changing the present technology of recording information on paper for the purpose of communication. It is suggested that the problems arising from the continued use of this technology seem to be significant and that techniques are readily available for the development of alternative solutions.     

Need for Broadband Infrastructure in a 2020 Perspective

The need for broadband capacity in the access networks by 2020 is discussed in this paper. A large range of countries around the world has decided to strengthen their resolve to have their broadband infrastructures built out and upgraded. The size of bandwidth requirements is, however, not an issue, which has been subject to much analysis from an academic angle whereas a number of consultancy reports with estimations on bandwidth needs for different services can be found. The needs for broadband access up until 2020 are discussed by scrutinizing the different services and applications requiring bandwidth. The bandwidth requirements in question are those of residential users and SMEs. In the paper it is assumed that users of broadband connections will use broadband for all their digital communications and further the paper focuses on the requirements for bandwidth notwithstanding the pricing of access. It is the estimated bandwidth need and not the actual demand, which is the subject of analysis. Scenarios including different types of households and different kinds of SMEs are presented.     

网络视频服务亟需实现模式创新

互联网2.0时代的网络视频服务迅缀发展,服务类型丰富多彩。但随着用户规模的不断扩大,网络视频服务企业的实际收入并没有实现有效增长,盈利模式仍需探索。面向未来,网络视频服务行业将向移动视频领域、商业服务领域和可控可管及有QoS保障领域延伸,并获得新的发展契机。     

通信管道设计中应注意的几个问题

介绍了几种常见通信用塑料管的特点、使用范围，最小埋设深度，以及与其他管线的最小隔距。     

无需微处理器控制的555定时器LED驱动器

从高端视频显示器到低端的照明,LED在很多领域得到了应用。设计者经常只需要一个专用LED驱动器功能的一部分,但不能承受用微控制器进行控制的成本。微处理器一般用于控制专用LED驱动器,实现例如对LED电流的模拟或PWM(脉冲     

The Need of Terahertz Cameras for Standardizing Sensitivity Measurements

The applicability of a blackbody source to sensitivity measurements and calibration of an uncooled Terahertz (THz) focal plane array (FPA) is discussed, but the combination of a blackbody source and a band-pass filter may not be suitable for these purposes. Two ways to measure the minimum detectable power (MDP) of uncooled THz-FPAs are described and compared when used with strong THz sources such as a quantum cascade laser (QCL). The MDP is defined as the radiant power that produces a signal-to-noise ratio of unity in the output of a THz imager that uses a THz-FPA operating at a TV frame rate. One method (method 1) is based on the hypothesis that the beam pattern of the THz source is close to a Gaussian pattern. In another method (method 2), the signal level of the background in an image that does not contain a THz source is subtracted from the signal of the image. While method 2 is more flexible, how large the signals coming from THz source should be, as compared with the noise level, remains to be defined. Finally, based on issues with the current non-uniformity correction (NUC) technique, specifications are proposed for THz source power and wobbling technique to obtain uniform illumination for an ideal NUC technique.     

Storing power for critical loads

The operation of systems for superconducting magnetic-energy storage (SMES) is explained. The original goal was systems storing thousands of megawatts of back-up electricity for several hours at a time, to help utilities meet peak power demands. The first commercially available unit rapidly stores and delivers much less electricity over much briefer periods-megawatts for seconds only. It excels in its handling of power glitches, an increasingly expensive problem in industrial applications of digital control equipment, and for other electronic equipment. The advantages of SMES for these applications are examined, and some field test results are discussed     

新型媒体处理器应对汽车电子发展需求

2006年北京国际车展于11月开展,据称这次展览共吸引了六十余万名观众.不知是有意还是巧合,三家半导体公司在同期纷纷推出了针对汽车应用的媒体处理,新产品在性能,针对性以及灵活性等方面均得到了进一步的提升.     

宽带和移动唤醒企业对VPN的需求

目前，互联网的方便性、高速接入和广阔的覆盖并没有被企业网络充分应用。究其原因这是出自于企业的IT经理对互联网安全性的担忧。任何企业的IT经理都不会将企业内部网络直接连接到互联网络中。一般情况下，企业内部网络与互联网互通都会设置防火墙．只允许内部网络节点向互联网发起请求，进行     

Software testing for safety critical applications

Software quality indicates how well the software product complies with the user requirements. Safety-critical applications in industrial automation such as industrial measurement and instrument software pose unique concerns for software quality due to its demanding requirements on system performance. Effective software testing can ensure the software quality as well as help the developer garner customer kudos for high-quality software. In this article, various issues on industrial measurement and instrument software testing are discussed. (Code inspections and audits are complementary activities to software testing and are very effective. This article addresses only testing; it does not address code inspections and review).     

Designing risk-management strategies for critical engineeringsystems

Effective management of the tradeoff between productivity and safety is a challenge in many industries that operate critical engineering systems such as nuclear power plants or offshore oil platforms. The objective of this paper is to link risk-management strategies to a system's safety and productivity over its lifetime. These strategies involve decisions that affect the physical system both directly and indirectly though the performance of the personnel that design, construct, or operate it. The problem is thus to link the different components of such risk-management strategies to human and system performance. In this paper, we present the basis of a decision support framework for the design and assessment of different risk-management strategies in risk-critical systems. First we discuss the inherent difficulty in balancing productivity and safety in the short and the long term and the different components of a risk-management strategy. We present a model involving both production failures and catastrophic failures as a function of strategic alternatives. This model is based on a probabilistic and dynamic risk analysis of a system, linking different aspects of risk-management strategies to specific characteristics of the physical system. We show how this model, coupled with explicit value judgments, can be used to design optimal strategies, e.g., to balance initial costs, long-term operations and maintenance costs, and the potential costs of catastrophic failures. To illustrate the concepts we use the case of the maintenance of a corporate airplane