Hewlett-Packard

About: Hewlett-Packard is a company organization based out in Palo Alto, California, United States. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 34663 authors who have published 59808 publications receiving 1467218 citations. The organization is also known as: Hewlett Packard & Hewlett-Packard Company.

Supplying power to an electronic device using multiple power sources

Abstract: An electronic device includes multiple power sources (102, 104, 202, 206, 302, 304) that can provide power to a load (106, 208, 306) in the electronic device. A DC-DC converter (110, 204, 310) is provided between one of the multiple power sources and the load.

Conversations over video conferences: an evaluation of the spoken aspects of video-mediated communication

Abstract: Recent trends toward telecommuting, mobile work, and wider distribution of the work force, combined with reduced technology costs, have made video communications more attractive as a means of supporting informal remote interaction. In the past, however, video communications have never gained widespread acceptance. Here we identify possible reasons for this by examining how the spoken characteristics of video-mediated communication differ from face-to-face interaction, for a series of real meetings. We evaluate two wide-area systems. One uses readily available Integrated Services Digital Network (ISDN) lines but suffers the limitations of transmission lags, a half-duplex line, and poor quality video. The other uses optical transmission and video-switching technology with negligible delays, full duplex audio, and broadcast quality video. To analyze the effects of video systems on conversation, we begin with a series of conversational characteristics that have been shown to be important in face-to-face interaction. We identify properties of the communication channel in face-to-face interaction that are necessary to support these characteristics, namely, that it has low transmission lags, it is two way, and it uses multiple modalities. We compare these channel properties with those of the two video-conferencing systems and predict how their different channel properties will affect spoken conversation. As expected, when compared with face-to-face interaction, communication using the ISDN system was found to have longer conversational turns; fewer interruptions, overlaps, and backchannels; and increased formality when switching speakers. Communication over the system with broadcast quality audio and video was more similar to face-to-face meetings, although it did not replicate face-to-face interaction. Contrary to our expectations, formal techniques were still used to achieve speaker switching. We suggest that these may be necessary because of the absence of certain speaker-switching cues. The results imply that the advent of high-speed multimedia networking will improve but not remove all the problems of video conferencing as an interpersonal communications tool, and we describe possible solutions to the outstanding problems.

Microwave signal generation with injection-locked laser diodes

Abstract: Heterodyne detection of the light from two slave lasers injection locked to FM sidebands of a modulated master laser is used to generate a narrowband microwave signal at 10.5 GHz.

Quality is in the eye of the beholder: meeting users' requirements for Internet quality of service

Abstract: Growing usage and diversity of applications on the Internet makes Quality of Service (QoS) increasingly critical [15]. To date, the majority of research on QoS is systems oriented, focusing on traffic analysis, scheduling, and routing. Relatively minor attention has been paid to user-level QoS issues. It is not yet known how objective system quality relates to users' subjective perceptions of quality. This paper presents the results of quantitative experiments that establish a mapping between objective and perceived QoS in the context of Internet commerce. We also conducted focus groups to determine how contextual factors influence users' perceptions of QoS. We show that, while users' perceptions of World Wide Web QoS are influenced by a number of contextual factors, it is possible to correlate objective measures of QoS with subjective judgements made by users, and therefore influence system design. We argue that only by integrating users' requirements for QoS into system design can the utility of the future Internet be maximized.

F-bounded polymorphism for object-oriented programming

Abstract: Bounded quantification was introduced by Cardelli and Wegner as a means of typing functions that operate uniformly over all subtypes of a given type. They defined a simple “object” model and used bounded quantification to type-check functions that make sense on all objects having a specified set of “attributes.” A more realistic presentation of object-oriented languages would allow objects that are elements of recursively-defined types. In this context, bounded quantification no longer serves its intended purpose. It is easy to find functions that makes sense on all objects having a specified set of methods, but which cannot be typed in the Cardelli-Wegner system. To provide a basis for typed polymorphic functions in object-oriented languages, we introduce F-bounded quantification. Some applications of F-bounded quantification are presented and semantic issues are discussed. Although our original motivation was to type polymorphic functions over objects, F-bounded quantification is a general form of polymorphism that seems useful whenever recursive type definitions and subtyping are used.