Solvent alternatives for the 1990s

The Montreal Protocol controls the manufacture and use of substances that deplete the Earth's stratospheric ozone. Amongst the chemicals under regulatory control are two halogenated solvents used widely in the electronics industry: CFC-113 and 1.1.1 trichloroethane. The paper gives the environmental science of ozone depletion and its ecological impact. The properties and uses of the common halogenated solvents are discussed and the range of more environmentally acceptable cleaning options, suitable for the applications in the electronics industry, are given     

通信传输技术九十年代新动向

本文概述九十年代通信技术的新动向,主要讲卫星通信、移动通信、光纤通信以及公用和专用通信网传输技术的发展趋势。文中着重指出各种有前途的新技术,包括卫星通信的星上点波束天线,小孔径天线地面终端,与ISDN兼容;数字移动通信的蜂窝微区(micro-cell),个人便携通信的无线接入交换网;光纤通信的掺铒光纤放大器,DFB调谐单频激光管,多量子阱(MQW),光电子集成,外差检测,密集FDM多路载波通信;以及公用通信网数字化、综合化、宽带化组成B-ISDN,同步光纤网,同步数字体系,异步转移方式;专用通信网的局域网(LAN和MAN),光纤分布数据接口,分隙环(slotted ring),分布排队双总线等新建议。     

FDDI and beyond-a network for the 1990s

The availability of cheap optical fibre and associated transceivers has encouraged the development of the next generation of computer networks. Most prominent among these is the fibre distributed-date interface (FDDI), which is expected to become a standard. The authors describe the principal advantages of the FDDI (namely its size and transmission rate) and outline the apparently bright future of FDDI networks and their applications     

New video coding standard for the 1990s

The growth of a conversational audio-visual service such as videoconferencing depends on an ability to provide a complete system at a price the customer can afford. Video compression technology can play a significant role by drastically reducing transmission costs. The paper outlines progress in establishing a new standard, H.261, for video coding bit rates between 64 kbit/s and 2 Mbit/s     

Satellite Scenarios and Technology for the 1990's

Commercial satellite communications continues to undergo changes arising not only from advancing technology but also from new service offerings and regulatory activities. As the communications industry grows more competitive, future directions in satellite communications will become more economically than technologically motivated. This paper addresses the future of satellite communications, emphasizing fixed satellite services but also covering maritime mobile and broadcast satellite services. Following a brief recapping of the past, current services are discussed and future services are projected for the above service categories. A projection is made of the economics of satellite communications systems using gateway and varying degrees of distribution of earth stations, for both INTELSAT VI and future multibeam satellites and the TAT-8 fiber-optic undersea cable. After a brief allusion to systems design considerations, the anticipated technology projections towards the year 2000 for satellite communication services (including satellite antennas, transmitters and receivers, and on-board interconnection subsystems) are presented in some detail. Finally, it is concluded that satellite communications will have a major role in this epoch, and widespread use of low-cost customer premise earth station may justify more sophisticated and more expensive spacecraft.     

Applied neural control in the 1990s

The authors describe some of the current neural prostheses and examine technological developments needed for future generations of neural prosthetic implants. Current developments include the peroneal nerve stimulator, upper and lower extremity functional neuromuscular stimulation and the auditory prosthesis. Three issues connected with future developments include stimulating and recording electrodes, the interconnection system, encapsulation, the command unit, force, touch, and position sensors, and signal conditioning     

Green energy? Electricity in the 1990s

All conventional energy sources are now under attack from conservationists, and the changing ESI privatisation plans have cast a cloud over Britain's nuclear future. The author discusses the state of fossil fuel power production in the UK and then discusses the alternatives including renewable energy sources. The possibilities of using wind energy and a Severn barrage are discussed. The effects on the environment of renewables is also discussed     

ASTER as a source for topographic data in the late 1990s

Topography is a fundamental Earth characteristic that can be measured for studies of the land surface. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the EOS-AM1 platform will acquire along-track stereo data for topographic mapping. ASTER is capable of recording 771 digital stereo pairs per day, each covering 60×60 km on the ground, at 15-m resolution, with a base-to-height ratio of 0.6. According to present plans, approximately 30 digital elevation models (DEMs), accurate to within ±7 to ±50 m (RMSE_z) will be produced daily by processing facilities in Japan and the United States. The Land Processes Distributed Active Archive Center (LP-DAAC) at the United States Geological Survey's (USGS's) EROS Data Center (EDC) will emphasize the use of automated stereocorrelation procedures to produce absolute DEMs tied to ground control. During the six-year mission, ASTER has the potential to provide a coherent, digital stereo data set covering all of the Earth's land surface. At minimum, ASTER DEMs will augment topographic data from other sources. Results of simulations of ASTER stereo data using existing satellite and aircraft data over validation sites in Huntsville, AL, and Iguala, Mexico, illustrate the value of high-resolution ASTER DEMs and how actual ASTER DEMs will be validated     

Chinese Cinema's Economic Reform From the Mid-1980s to the Mid-1990s

Since the mid-1980s, the Chinese audiovisual industry has gone through a series of institutional reforms aimed at decentralization and marketization. The reform measures from the mid-1980s to the mid-1990s affected the general trend in film production and criticism during the period. The outcome of film reform has been the commercialization and privatization of the Chinese film industry and the surge of entertainment pictures. Meanwhile, the global popularity of Hollywood pictures (re)defined what counted as quality films for Chinese audiences. As such, the industrial structure and market practice institutionalized by Hollywood have become the new model for the Chinese film industry. Approached from an institutional perspective, this article gives major attention to the structural formation of the market and the audiovisual industries, that is, the industries' ownership and control related to state policy.     

Telecommunication applications of the 1990s and their transportrequirements

The extent of the diversity in telecommunication services of the next decade is investigated, using a number of transport-oriented characteristics. Groups of services that have similar transport requirements are identified. The results are shown to have implications on priority considerations in the headers of asynchronous time-division multiplexing (ATDM), otherwise known as asynchronous transfer mode, cells, and also to provide an introduction strategy for ATDM switching into the present network. A detailed service characterization and a taxonomy of services are included     

Eos: The earth observing system of the 1990s

In this paper the recent considerations of NASA's Earth Observing System Science and Mission Requirements Working Group are summarized. The Working Group was chartered to consider the broad Earth Science objectives that could be addressed from a low-earth orbital perspective in the 1990s, together with consideration of the specific observations and instrument packages that would be needed to meet the science objectives. The concept that was developed diverges somewhat from past practices in that the Working Group chose to consider Eos as an information system, where mission operations, Eos databases, and information about other relevant data sets are tied together by an information network. The network would link users with mission data repositories, with Eos and non-Eos data archives, and with subsets of Eos and related data maintained as active research databases. Three Eos instrument packages were chosen on the basis of synergistic groupings of instruments to make simultaneous observations of selected phenomena over a variety of wavelengths. The suggested packages are: 1) a surface-imaging and-sounding package, with two imaging spectrometers, a high-resolution multifrequency microwave radiometer, and a Lidar atmospheric sounder and altimeter; 2) an active microwave package, with a synthetic-aperture radar, an altimeter, and a scatterometer; and 3) an atmospheric physical and chemical monitoring package, with a variety of instruments to measure atmospheric chemistry, winds, and energy balances. The significant observing capabilities offered by the Eos instrument packages, if implemented in the proposed information system environment, will allow significant increases in our understanding of global processes operating above, on, and beneath the earth's surface.     

The current state of the reflector antenna are-entering the 1990s

Modern reflector theory and practice, with emphasis on the recent past are reviewed. Included are a brief historical review and performance definitions for the nonspecialist. Special sections are devoted to shaped multiple reflectors, reflector surface metrology, and reflectors for the next decade and beyond. In spite of decreasing budgets for scientific, commercial, and military space programs, the 1990s promise to be a true golden age for the reflector antenna art     

In our image: interface design in the 1990s

People, not technology, have become the focus of current interface design. Multimedia interface designers try to take advantage of human senses to ease our communication with one another and with the computer. This survey of current work highlights the complexity facing them in their task     

Rain side-scatter interference in the satellite links of the 1990s

In addition to inducing attenuation and depolarization in satellite links, scattering by rain can create intersystem interference. This type of interference was investigated extensively in the 1970s for terrestrial paths, but little has been done to study its effects on modern and future satellite links. Studies of the potential interference created by the scattering of an uplink signal into an adjacent satellite and the inverse case where a downlink signal is scattered into the earth station of an adjacent satellite system are reported. Two computation methods for the interfering power are presented. The first, based on the bistatic radar equation, takes only the first-order multiple scattering into account, whereas the second method, based on the radiative transfer equation, includes higher orders of multiple scattering     

Automobile electronics in the 1990s .2. Chassis electronics

There can be few topics developing faster than automotive electronics. Although the application of microcomputer-based systems is now well established for the control of automobile engines, there is still greater scope for the use of high-reliability electronic technology in other areas of vehicle operation. Amongst these are systems, such as air-bags, which improve safety, and also features which improve comfort and convenience. In this paper the operation of electronically controlled antilock braking systems (ABS) and electrically power-assisted steering (EPAS) is examined     

二十世纪九十年代的通信卫星技术和业务

从商用和军用两个方面论述了卫星通信的未来。讨论了卫星通信的技术发展和新业务。同时，对用户和需求进行了评估。     

A scenario for the deployment of interactive multimedia cabletelevision systems in the United States in the 1990s

This paper discusses the key technologies that are enabling the transition from analog to digital interactive television. Also discussed is a proposed three-phase scenario for the U.S. deployment of interactive multimedia cable television systems during the remainder of the decade of the 1990s and some of the social implications of such networks