Structure of Saturn's rings: Optical and dynamical considerations

The photometric phase curves of Saturn's rings are considered, as well as a conflict between dynamical and photometric models of the rings. The dependence of ring brightness on angular separation of the earth and sun as viewed from Saturn is discussed. The nonlinear brightness surge is interpreted. Some quantitative calculations were carried out for bodies in and near the asteroidal belt. Predicted density profiles of the ring obtained with Mimas in an eccentric orbit and in a circular orbit are also included

Study of lunar earthshine by photoelectric photometry Final report, 1 Nov. 1965 - 30 Sep. 1967

Design feasibility and performance of semiportable field instrument for monitoring changes in earth albedo via earthshine measurement

Lorentz contraction, Bell's spaceships, and rigid body motion in special relativity

The meaning of Lorentz contraction in special relativity and its connection with Bell's spaceships parable is discussed. The motion of Bell's spaceships is then compared with the accelerated motion of a rigid body. We have tried to write this in a simple form that could be used to correct students' misconceptions due to conflicting earlier treatments.Comment: Modified the discussion in Sec. 2. This version to be published in European Journal of Physic

Logic Simulation: Statistics and Machine Design

The high costs associated with logic simulation of large VLSI based systems have led to the need for new computer architectures tailored to the simulation task. Such architecture have the potential for significant speed-ups over standard software based logic simulators. Several commercial simulation engines have bene produced to satisfy needs in this area. To properly explore the space of alternative simulation architectures, data is required on the simulation process itself. This paper presents a framework for such data gathering activity and uses the data in estimating the maximum speed-up attainable with a particular type of special-purpose parallel/pipelined simulation machine. First, possible sources of speed-up in the logic simulation task are examined. Then, the sort of data needed in the design of simulation engines is discussed. Next, the data is presented and the implication on machine design are discussed. This data includes information on subtask times found in standard discrete-event simulation algorithms, event intensities, queue length distributions, and simultaneous event distributions. Finally, a simple performance model of one type of simulation machine is developed, and the maximum speed-up attainable with this type of machine is predicted

VLSI Based Interconnection Networks

Interest in tightly coupled multiprocessor computer systems has grown as the possibilities for high performance with such systems have been recognized. Central to their design is the structure of the network over which the processors communicate. Unless properly designed, such networks can be both a cost and performance bottleneck. This paper focuses on the design of VLSI communications networks, this is, on communications network which can be placed on a single VLSI chip. Traditional SSI-based boost and complexity measures for such networks have principally involved switch aggregate counts. In a VLSI domain, however, more appropriate measures involve chip area, and space-time product. The effects of network topology and VLSI layout on these measures are reviewed with regard to two network types. Another important question related to the VLSI communication network problem related to the chip pin constraints. This problem is discussed and some effects and options presented by bit slice network designs are described

PIN Limitations and VLSI Interconnection Networks

Multiple processor interconnection networks can be characterized as having N\u27 inputs and N\u27 outputs, each B\u27 bits wide. Construction of large networks requires partitioning of the N\u27*N\u27*B\u27 network into a collection of N*N switch modules of data size B (

Some Service Failures arising from Various Types of Corrosion

The Research Laboratory of the Development and Research Department of The Mond Nickel Company Limited, has been concerned is developing new heat and corrosion-resistant alloys to meet the demands of designers of gas-turbine chemical plant and electrical equipment.Premature service failures in these materials are not common, and when they do occur they can usually be traced to misuse or mal-treatment of the material during fabrication or appli-cation, or to some form of accidental contamination or damage. Important lessons have nevertheless been learned from post-mortem examinations of service failures, and the following five examples have been selected as of interest not only to works' metallurgists but also to designers, to whom these special materials offer new possibilities, and to fabricators, to whom they present certain problems

Parallel Machines and Algorithms for Discrete-Event Simulations

A number of recent articles have focused on the design of high speed discrete-event simulation (DES) machines for digital logic simulation. These investigations are in response to the enormous costs associated with the simulation of complex (VLSI) digital circuits for logic verification and fault analysis. One approach to reducing simulation costs is to design special purpose digital computers that are tailored to the logic simulation test. This paper is concerned with the architecture of such logic machines. The paper has three principal parts. First, a taxonomy of logic machine architectures is presented. The taxonomy focuses on the central components of the logic simulation algorithms and on architectural alternatives for increasing the speed of the simulation process. It thus represents a basis for discussing and differentiating between proposed architectures and also results in the identification of several new architectures. Although developed for digital logic simulators., the taxonomy can be used for general DES machines. Second, a performance measure is presented which permits evaluation of DES machines. Finally several DES machine designs are described and categorized using the taxonomy