Search

I N a previous publicationi we have analyzed the reflection of a plane electromagnetic wave on a rough surface. Due to an error in sign* in Eq. (3.6) of the foregoing reference the sign on the right side of Eqs. (3.7) and (3.9) must also be changed. This amounts to replacing the “roughness parameter” r by -(r throughout the paper. In particular the boundary condition (7.8) for the case of vertical polarization should read

A significant factor which affects the accurate prediction of the discharge coefficients of square edged orifice plates is the precise shape of the edge. A rounding of only 0·002 of the orifice diameter can increase the coefficient by 1% so that a reliable method of assessing the edge sharpness is of considerable benefit to the instrument engineer. In the work described in this paper, a systematic intercomparison of three methods of measuring orifice edge sharpness has been undertaken. The methods tested involved casting, lead foil impression and optical techniques, and their relative reliability and effectiveness has been assessed. While the results obtained from the casting and lead foil methods showed good agreement, the foils did not follow the edge profiles as closely as the castings. The casting procedure can also be used to determine the shapes of re-entrant profiles which will not be detected using lead foil impressions. However, the casting method required more skill and considerably more time to complete measurements than the impression method. The optical method proved to be the least reliable, since measurements depended on subjective judgment. Nevertheless, this measuring procedure could be completed more quickly than the others, and these tests indicated that it may be used to examine large diameter plates for burrs or excessive rounding.

This paper extends the usefulness of an earlier report by evaluating an approximation for the transient response. The approximation examined is that of equivalent oil column stiffness; this has been used in the past, without evaluation, for displacement but is extended here to cover pressure transients. The comparisons between approximate and correct displacement responses indicate that the former is of sufficient accuracy for most practical purposes. In the two very different cases investigated, the approximation gives conservative estimates of the pressure peak.

The aim of the work presented here is to enlarge the subset of VHDL which can be manipulated by formal verification tools by including the timing constructs. In this paper we give formal semantics for these constructs. And, we prove, partially, the equivalence between these semantics and the informal operational semantics of the language as defined in the VHDL language reference manual. Also, we show how these semantics can establish a basis for the construction of formal timing verifiers.

The paper first offers a parallel between two approaches to conceptual clustering, namely formal concept analysis (augmented with the introduction of new operators) and bipartite graph analysis. It is shown that a formal concept (as defined in formal concept analysis) corresponds to the idea of a maximal bi-clique, while sub-contexts, which correspond to independent "conceptual worlds" that can be characterized by means of the new operators introduced, are disconnected sub-graphs in a bipartite graph. The parallel between formal concept analysis and bipartite graph analysis is further exploited by considering "approximation" methods on both sides. It leads to suggest new ideas for providing simplified views of datasets, taking also inspiration from the search for approximate itemsets in data mining (with relaxed requirements), and the detection of communities in hierarchical small worlds. © 2013 Copyright the authors.

This paper describes a procedure for simulation of digital control systems on an analog computer with digital logic. The digital elements are only those normally provided in the digital panel now available as an optional accessory from most analog computer manufacturers. When used in conjunction with the conventional analog amplifiers and integrators connected as track-hold devices, it is possible to simulate complete systems which include not only the straightforward single-rate system but also those having two or more sampling rates or subsystems, and those having delayed or skip sampling characteristics. The digital logic connections for some simple but typical problems are given and are suggestive of those required for more sophisticated applications. A couple of oscilloscope photographs are included which show the informative presentation which can be obtained with this simulation technique.

International audience; This paper presents an overview of a comprehensive collection of on-line testing techniques for VLSI. Such techniques are for instance: self-checking design, allowing high quality concurrent checking by means of hardware cost drastically lower than duplication; signature monitoring, allowing low cost concurrent error detection for FSMs; on-line monitoring of reliability relevant parameters such as current, temperature, abnormal delay, signal activity during steady state, radiation dose, clock waveforms, etc.; exploitation of standard BIST, or implementation of BIST techniques specific to on-line testing (Transparent BIST, Built-In Concurrent Self-Test, ...); exploitation of scan paths to transfer internal states for performing various tasks for on-line testing or fault tolerance; fail-safe techniques for VLSI, avoiding complex fail-safe interfaces using discrete components; radiation hardened designs, avoiding expensive fabrication process such as SOI, etc.

The fitting of mathematical models to physiological sys tems can be tedious and difficult, whether one uses analog or digital computer methods. Both methods have their pros and cons depending on the available hardware and software and on the type of modeling. In recent years many digital simulation languages have been written com bining analog-like and digital features to facilitate model ing, but, for a variety of reasons, none of these was suit able for our applications. We, therefore, designed a new digital simulation control system, SIMCON, which is de scribed in this paper. The primary objectives were to provide: (1) Maximum man-machine interaction at run-time, in cluding visual displays, digital control, and both con tinuous analog and digital parameter adjustment (2) The ability to generate solutions and to fit them to experimental data or other theoretical curves with a minimum of computer memory (3) The option to use a mathematically oriented language, FORTRAN, and block operators with variable input/ output. The result is a relatively general and simple simulation system which is easy to use and has wide versatility.