Magnetic Attitude Control for Satellites in Polar or Sun-Synchronous Orbits

In this work, a new law for magnetic control of satellites in near-polar orbits is presented. This law has been developed for the UMPSat-2 microsatellite, which has been designed and manufactured by Universidad Politécnica de Madrid, Madrid. The control law is a modification of the B-dot strategy that enables the satellite to control the rotation rate. Besides, the satellite?s equilibrium state is characterized by having the rotation axis perpendicular to the orbit?s plane. The control law described in the present work only needs magnetometers and magnetorquers, as sensors and actuators, respectively, to carry out a successful attitude control on the spacecraft. A description of the analysis is included. Performance and applicability of the proposed method have been demonstrated by control dynamics together with Monte Carlo techniques and by implementing the control law in the UPMSat-2 mission simulator. Results show good performance in terms of acquisition and stability of the satellite rotation rate and orientation with respect to its orbit?s plane.

Voice-processing technologies--their application in telecommunications.

As the telecommunications industry evolves over the next decade to provide the products and services that people will desire, several key technologies will become commonplace. Two of these, automatic speech recognition and text-to-speech synthesis, will provide users with more freedom on when, where, and how they access information. While these technologies are currently in their infancy, their capabilities are rapidly increasing and their deployment in today's telephone network is expanding. The economic impact of just one application, the automation of operator services, is well over $100 million per year. Yet there still are many technical challenges that must be resolved before these technologies can be deployed ubiquitously in products and services throughout the worldwide telephone network. These challenges include: (i) High level of accuracy. The technology must be perceived by the user as highly accurate, robust, and reliable. (ii) Easy to use. Speech is only one of several possible input/output modalities for conveying information between a human and a machine, much like a computer terminal or Touch-Tone pad on a telephone. It is not the final product. Therefore, speech technologies must be hidden from the user. That is, the burden of using the technology must be on the technology itself. (iii) Quick prototyping and development of new products and services. The technology must support the creation of new products and services based on speech in an efficient and timely fashion. In this paper I present a vision of the voice-processing industry with a focus on the areas with the broadest base of user penetration: speech recognition, text-to-speech synthesis, natural language processing, and speaker recognition technologies. The current and future applications of these technologies in the telecommunications industry will be examined in terms of their strengths, limitations, and the degree to which user needs have been or have yet to be met. Although noteworthy gains have been made in areas with potentially small user bases and in the more mature speech-coding technologies, these subjects are outside the scope of this paper.

Supersaturation of nitrogen gas caused by artificial aeration in reservoirs /

At head of title: Environmental & Water Quality Operational Studies.

New directions in telecommunications policy /

Includes bibliographies and indexes.

Information products resulting from satellite studies at the Institute for Telecommunication Sciences /

May 1977.

Fixed-satellite and broadcasting-satellite service considerations for 1979 GWARC planning /

Issued Oct. 1978.

Study of satellite frequency requirements for the U.S. Postal Service electronic mail system /

v.1 Summary -- v. 2. Frequency allocations and network designs -- v.3 Technology studies

Interim report on channel deterioration study of natural and artificial drainageways in Republican, Loup, and Little Sioux River areas, Nebraska and Iowa.

Mode of access: Internet.

Artificial fertilizers in modern agriculture.

Bibliography: p. 193.

Hydraulic investigation for the construction of artificial islands in Peoria Lake : final report /

Prepared for Illinois Dept. of Energy and Natural Resources, Energy and Environmental Affairs Division.

A treatise on the operations for the formation of an artificial pupil; in which the morbid states of the eye requiring them, are considered ...

Mode of access: Internet.

Communications satellites : challenges of the future.

Mode of access: Internet.