Direct Ranking for Voltage Contingency Selection

It is now commonly accepted that for security assessment of a power system, the most efficient and practical strategy is to deal with the problem in two stages. First in contingency selection, those potentially critical contingency cases are ranked by the severity of their impacts on a system. Then in contingency analysis, detailed AC power flows are applied only to the most dangerous cases appearing on top of the ranked list. In the past decade, the problem of ranking outage cases in the order of decreasing severity has attracted a lot of intensive studies, and many efficient and reliable algorithms were developed. But most of these techniques can only be applied to MW limit security problems. On the other hand, voltage problems were also found to be a very important aspect of security assessment. It has become the target of many research projects. Because the MVAR-voltage problem involves a much more complicated model than the MW-angle problem, significant obstacles were experienced in developing ranking algorithms for voltage security monitoring, making it an area where further study is still required. Almost all contingency ranking algorithms employ a scalar performance index to represent a global severity of voltage disturbance after a contingency event. The scalar performance index can be viewed as a weighted distance in voltage space measuring the post contingency voltage profile against specified voltage limits.     

Design of fiducials for accurate registration using machine vision

The effect of the shape and size of a standard feature (fiducial) on the positional accuracy of the centroid in machine-vision applications is studied. It is shown that a circular fiducial provides superior subpixel registration accuracy among the fiducial shapes typically used today     

Laser flash photolysis and magnetic-field-effect studies on interaction of thymine and thymidine with menadione: role of sugar in controlling reaction pattern

The magnetic field effect (MFE) in conjunction with laser flash photolysis has been used for the study of the interaction of one of the small drug like quinone molecules, 2-methyl, 1,4-naphthoquinone, commonly known as menadione (MQ), with one of the DNA bases, thymine (THN), and its corresponding nucleoside, thymidine (THDN), in acetonitrile (ACN) and sodium dodecylsulfate (SDS) micelles. It has been observed that THN undergoes electron transfer (ET) and hydrogen (H) abstraction with MQ, while THDN undergoes only H abstraction in both the media. However, our earlier studies showed that a purine base, adenine (ADN), and its nucleoside, 2′-deoxyadenosine (ADS), undergo ET in ACN and H abstraction in SDS. Here we have attempted to explain the differences in the reactions of these DNA bases with MQ. We also reveal the crucial role of a sugar unit in altering the behavior of purine and pyrimidine bases with respect to ET and H abstraction.     

Performance analysis under dynamic loading of wavelength continuous and non‐continuous WDM networks with shortest‐path routing

The performance of WDM networks using shortest path routing is studied under wavelength continuous (WC) and non‐continuous (NWC) constraints and dynamic traffic loading. Approximate analytical models are presented for the performance studies of such systems. Results of numerical calculations based on these models and simulations are given for different network topologies for the purposes of comparison. These analytical and simulation results are used to study the performance of these WDM networks under dynamic traffic loading. Copyright © 2001 John Wiley & Sons, Ltd.     

A theoretical and experimental study of noise and distortion in thereception of FM signals

A mathematical model is developed that can be used to analyze the effects of multipath on any modulation of an FM carrier. The predictions of this model are verified by simulation and by actual field testing. The model is used to analyze the existing FM stereo system and the proposed FMX system. The analysis, confirmed by field tests in over 15 000 locations, shows that FMX transmission significantly degrades reception on existing FM stereo receivers and that FMX receivers are inferior to FM stereo receivers for receiving FMX transmissions     

Improvement of nonisothermal oxidation behavior of fe and fe-cr alloys by superficially applied reactive oxide coatings

The nonisothermal oxidation behavior of pure iron and a few iron-chromium alloys in dry air has been studied. The effects of a superficial coating of a reactive oxide, CeO₂, on the oxidation behavior were studied. Linear heating rates of 3 K/min and 6 K/min were maintained up to a final temperature ranging from 1273–1473 K. Coatings were applied either from a slurry or an aqueous bath. The CeO₂ coating has been found to be effective not only in decreasing the nonisothermal oxidation rate but also in improving the scale adherence. Moreover, the coated samples withstood a number of heating cycles without scale rupture. The mass gain of the samples as a function of temperature was recorded by means of a sensitive balance, and the scales have been characterized by SEM, EPMA, and x-ray diffraction analysis.     

A Tutorial on GrÖbner Bases With Applications in Signals and Systems

This paper is a tutorial on GrÖbner bases and a survey on the applications of GrÖbner bases in the broad field of signals and systems. A reasonably detailed review is given of several fundamental theoretical issues that occur in the use of GrÖbner bases in multidimensional signals and systems applications. These topics include the primeness of multivariate polynomial matrices, multivariate unimodular polynomial matrix completion, and prime factorization of multivariate polynomial matrices. A brief review is also presented on the wide-ranging applications of GrÖbner bases in multidimensional as well as one-dimensional circuits, networks, control, coding, signals, and systems and other related areas like robotics and applied mechanics. The impact and scope of GrÖbner bases in signals and systems are highlighted with respect to what has already been accomplished as a stepping stone to expanding future research.