Discrete Convolution in Power System Reliability

This paper describes a general method for convolving discrete distributions using Fast Fourier Transforms. It can be used in evaluating reliability of any system involving discrete or discretised convolution. It has been used in power system studies to deduce capacity-outage probability tables and to solve probabilistic load flows. These studies have shown it to be much less time-consuming and more efficient than the conventional direct methods. The method is used in the paper to evaluate the loss of load probability of a generating system in order to demonstrate the method's application and inherent merits.     

Sudden incapacitation: USAF experience, 1970-80

During the period 1970-80, there were reported 146 cases of in-flight sudden incapacitation in the USAF. Of these, 62 involved pilots, 14 were navigators, and 70 were student pilots. The etiologies of sudden incapacitation included illness without loss of consciousness, loss of consciousness, spatial disorientation, and improper M-1 maneuver. Each of these categories is analyzed with emphasis upon prevention, for example, not flying with symptomatic preexisting disease, continued emphasis upon spatial disorientation training, and correct performance of the M-1 maneuver. Based upon the data, conclusions and recommendations are suggested to minimize the risk of episodes of in-flight sudden incapacitation.     

Effect of La2O3 doping on the microstructure and electrical properties of a SnO2-based varistor

The effect of La₂O₃ addition on the densification and electrical properties of the (0.9895-xSnO₂+0.01CoO+0.0005Nb₂O₅+x La₂O₅ system, where x=0.0005 or 0.00075, was considered in this study. The samples were sintered at 1300 °C for 2 and 4 h and a single SnO₂ phase was identified by X-ray diffraction. Microstructure analysis by scanning electron microscopy showed that the affect of La₂O₃ addition is to decrease the SnO₂ grain size. J versus E curves indicated that the system exhibits a varistor behavior and the effect of La₂O₃ is to increase both the non-linear coefficient () and the breakdown voltage (E₂). Considering the Schottky thermionic emission model the potential height and the width were estimated. The addition of small amounts of La₂O₃ to the basic system increases the potential barrier height and decreases both grain size and potential barrier width. © 2001 Kluwer Academic Publishers     

Lessons learned from the testing of RC frames with masonry infills and proposals for new solutions / Untersuchungen an mit Mauerwerk ausgefachten Stahlbetonrahmen und neue Lösungsvorschläge

Past experience has shown that inadequate design of unreinforced masonry walls (URM) or inadequate selection of materials can lead to significant economic losses and fatalities in the case of a strong earthquake. In this context, this paper presents the experimental research that has been carried out with the aim of gaining a better insight into the traditional masonry infill walls commonly built in Portugal. The experimental research includes: (1) shaking table tests on reduced‐scale reinforced concrete (RC) buildings with masonry infills with distinct typologies, from traditional solutions to those with enhanced properties and solutions to improve the seismic behaviour; (2) in‐plane static cyclic tests on a representative one‐storey, one‐bay RC frame with masonry infills with distinct typologies but similar to the ones tested in the RC building models. It was concluded that the typology of masonry walls influences the global behaviour of RC buildings, particularly when there is no connection between masonry infill and RC frame. An appropriate design is necessary to prevent an unforeseen failure mechanism due to shear stresses in the RC columns induced by the infill. The in‐plane cyclic tests showed that render plays a central role in the lateral strength and stiffness. Additionally, it was observed that bed joint reinforcement and reinforced render are important measures for controlling damage but do not significantly influence the in‐plane lateral strength and stiffness.     

Enhancement of pasta antioxidant activity with oregano and carrot leaf

Five different pasta formulations were prepared using different concentrations of carrot leaf meal (CLM) and oregano leaf meal (OLM). One control formulation (wheat flour and semolina, 70:30 w/w) and four other formulations were prepared using the following amounts of leaf meals: 5% CLM and 5% OLM (I), 10% CLM (II), 10% OLM (III), and 10% CLM, 10% OLM (IV). The highest content of alpha-linolenic acid was found in formulations II and IV, which also had a reduced n-6/n-3 ratio, 3.6 (IV), when compared to the control, which was 19.8. All the samples enhanced with leaf meals showed antioxidant activity by the DPPH radical method; however, it was higher in formulation IV, which was the same observed for phenolic compounds. Pasta added with leaf meals lost more solubles, had shorter cooking time and a lower weight increase than the control pasta. All formulations had significant sensory acceptance.     

Pseudo-chronological simulation for composite reliability analysiswith time varying loads

This paper presents a new methodology to evaluate loss of load indices, with particular emphasis on LOLC (loss of load cost) assessment, for composite generation and transmission systems considering time varying loads for different areas or buses. The proposed approach, named pseudo-chronological simulation, retains the computational efficiency of nonsequential Monte Carlo simulation and the ability to model chronological load curves in sequential simulation. It considers the actual blocks of unsupplied energy per consumer class, per bus, and the respective duration, to accurately characterize the interruption process. Case studies on the IEEE-MRTS (Modified Reliability Test System) and the BSS (Brazilian South-Southeastern System) are presented and discussed