Personal tools for becoming a more successful engineer

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Micro earth stations as personal computer accessories

Equatorial Communications Company has shipped more than 15000 micro earth stations, typically 24 in (60 cm) in diameter and costing under $3000 for reception of satellite data transmission. Many are used as data input devices for personal computers in distributed database applications. Equatorial is also developing low-cost interactive micro earth stations appropriate for connecting personal computers or terminals to remote host computers. Equatorial is also a satellite transponder owner and provider of packet-switched satellite network services to the installed base of micro earth stations. Spread-spectrum modulation techniques implemented in microprocessor technology are used in Equatorial networks and earth stations to provide high performance, including interference rejection, at very low cost.     

The Multi-angle Imaging SpectroRadiometer science data system, its products, tools, and performance

Ground processing of data from the Multi-angle Imaging SpectroRadiometer (MISR) instrument, part of NASA's Earth Observing System (EOS), exploits new and unique science algorithms not previously used operationally. A range of data products from Level 1 through Level 3 is being produced. Because of MISR's unprecedented design, extensive prototyping was required from a relatively early stage. The data throughput is large, necessitating an innovative software design approach that maximizes performance. The systematic science processing software was developed at the Jet Propulsion Laboratory, with data processing occurring at the NASA Langley Research Center using the EOS Core System, a collaborative arrangement that works well. With the availability of actual mission data following launch on the Terra spacecraft in December 1999, MISR's computational needs have become better known, and many improvements have been made to both the science software and the production system to achieve a successful overall data processing capability. This paper provides information about MISR data for the science user, and describes the nature and scope of implementation and operations activities.     

On the limitations of transimpedance amplifiers as tools for low-frequency noise characterization

An experimental set-up for the characterization of low-frequency noise on two terminal devices is reported. The experimental set-up is based on the use of the commercial transimpedance amplifier (TA) EG&G5182. This paper addresses the influence of the TA on the noise characterization process by describing the TA as a non-ideal operational amplifier with a feedback resistor. The impact of the TA finite input resistance and voltage gain is highlighted through comparison with measurements carried out on resistors and diodes.     

Personal network on the Internet: How the socially marginalized stay marginalized in personal network diversity and multiplicity

The Internet by its asynchronous and non-spatial nature may facilitate the diverse and multiple personal networks, but we hypothesize that this network affordance will be heavily influenced by one’s socio-demographic positions. To test this hypothesis, we used a large survey data set of Internet users (n = 3,120) and examined how users’ socio-demographic positions interact with Internet access to shape the affordance of network diversity and multiplicity. We found significant interactive effects, while network diversity, as indicated by homogeneity and heterogeneity, was not directly impacted by social positions. The effects of network multiplicity on personal wellbeing also differed by socio-demographic background. We argue that, without an understanding of socio-demographic disparities, a focus on Internet affordance fails to recognize the social reproduction in the creation and the benefits of personal networks.     

面向个人和家庭的远程医疗通信技术

近年来国际上开展了大量的面向个人和家庭的远程医疗中使用的通信技术的研究,其中国际产业联盟———康体佳健康联盟在这方面成果显著。本文通过介绍康体佳健康联盟的生态系统、市场关注和端到端参考构架,展现出远程医疗的应用模式、总体方案以及实现互联互通的关键技术。     

Design tools for analog and digital ICs

The era of the system on a chip is well under way, bringing in its train new headaches for the IC design engineer. One reason for the difficulties is that such systems are increasingly being built up from an assembly of pre-designed components-so-called intellectual property (IP) or virtual components-which sometimes come from diverse sources. Further, a decision is often demanded very early in the design process as to which functions will be executed in hardware and which in software, after which concurrent design of both components is necessary to ensure they work together. Then, too, the shrinking dimensions of the structures that make up the chip are compelling consideration of their physical and electrical properties in much more detail than ever before. All the while, market pressures are forcing companies to design and verify application-specific ICs with millions of logic gates in less and less time     

The case for CASE tools

The factors that are creating a demand for CASE (computer-aided software engineering) tools in all phrases of the software life cycle are identified. As CASE is beginning to extend its reach beyond software generation, the term is coming mean computer-aided systems engineering. The use of CASE in the typical software engineering process is described and CASE methodologies are briefly examined     

Perfluorooctyl Bromide Polymeric Capsules as Dual Contrast Agents for Ultrasonography and Magnetic Resonance Imaging

Polymeric capsules with a thick shell made of biodegradable and biocompatible polymer and a liquid core of perfluorooctyl bromide (PFOB) were evaluated for stability as well as for ultrasound and magnetic resonance imaging (MRI) contrast enhancement. The method of preparation allows the mean capsule diameter to be regulated between 70 nm and 25 µm and the capsule thickness‐to‐radius ratio from 0.25 to 0.54. Capsule diameter remains stable at 37 °C in phosphate buffer for at least 4 and 6 h for nanocapsules and microcapsules, respectively. The in vitro ultrasound signal‐to‐noise ratio (SNR) was measured from 40 to 60 MHz for 6 µm and 150 nm capsules: the SNR increases with capsule concentration up to 20–25 mg mL⁻¹, and then reaches a plateau that depends on capsule diameter (13.5 ± 1.5 dB for 6 µm and 6 ± 2 dB for the 150 nm capsules). The ultrasound SNR is stable for up to 20 min for microcapsules and for several hours for nanocapsules. For nanocapsules, the thinner the shell, the larger the SNR and the more compressible the capsules. Nanocapsule suspensions imaged in vitro with a commercial ultrasound imaging system (normal and tissue harmonic imaging modes, 7–14 MHz probe) were detected down to concentrations of 12.5 mg mL⁻¹. Injections of nanocapsules (200 µg ml⁻¹) in mice in vivo reveal that the initial bolus passage presents significant ultrasound enhancement of the blood pool during hepatic imaging (7–14 MHz probe, tissue harmonic imaging mode). ¹⁹F‐MRI images were obtained in vitro at 9.4T using spin‐echo and gradient echo sequences and allow detecting nanocapsules in suspension (50 mg mL⁻¹). In conclusion, these results show initial feasibility for development of these capsules toward a dual‐modality contrast agent.     

Planning tools for mobile networks

The RACE II project PLATON (Planning Tools for third generation mobile Networks) aims at defining a set of tools to be used for radio planning of the Universal Mobile Telecommunication Systems (UMTS) network. The paper presents studies on cell structures, propagation models, the different services and the corresponding quality-of-service and shows how these are used in the planning tools, the modular structure and the evolution of the software     

Satellite systems for personal communications

A number of industry groups are planning to construct satellite systems that will provide a personal communications service (PCS) (typically voice, data, and fax) to users over small, hand-held, cellular-type telephones. Some of these systems (e.g., Iridium and Globalstar) will be constructed using satellites in low Earth orbit. Two (Ellipso and ICO) will employ medium Earth orbit (3-8-h period), and still others (ACeS and Agrani) will operate from geostationary altitude. The origin and evolution of mobile satellite communications is discussed first, including the Inmarsat system and several land-based mobile satellite systems in operation. The rival approaches to the PCS market are then described, and some of the technical challenges inherent in each are indicated. This paper concludes with speculation on the factors influencing the likelihood of business success for the various PCS systems     

个人通信网和个人通信服务

作为第三代移动通信的创新概念“个人通信”被提出以来，个人通信网和个人通信服务从定义、理论、技术、设备等各方面得到不断发展和明显进步，得到全世界通信学界的极大重视，本文依据个人通信网的定义和现实发展，对个人通信网的研究发展方向，技术重点，实现个人通信服务所需求的功能和应用前景等进行讨论。     

基于软交换的个人监控通信

网络的融合及终端智能化程度的提高，为个人监控通信的实现提供了条件。借助于M2M技术，软交换网络可以为个人监控通信提供理想的实现平台。基于软交换的网络架构和实现原理，个人监控通信系统可分为网络侧和用户侧两部分。网络侧设备包括软交换机、现场业务中心等，位于核心控制层和业务层；用户侧设备包括监控设备、现场设备、网关和现场控制平台，位于接入层和现场设备层。通过基于软交换的个人监控通信系统可以实现家庭自动化、公共服务、资源调度、安全监测以及社群互助等多种人机通信业务。随着机器智能的提高和网络的融合，将来个人监控还会不断完善和发展，极有可能成为未来通信的主流业务之一。     

Digital modulation techniques for mobile and personal communicationsystems

The paper describes in detail various digital modulation techniques for mobile and personal communication systems. Among others, these include π/4-shift quadrature phase-shift keying (QPSK), used in the second generation digital cellular mobile systems in North America and Japan, and Gaussian minimum-shift keying (GMSK), employed in the GSM system in Europe. It then briefly discusses the current research activities in modulation schemes for future systems