Corrigendum for `Constraint-based automatic test data generation'by R.A. DeMillo and A.J. Offutt

In reference to the above-titled paper by R.A. DeMillo and A.J. Offutt (see ibid., vol.17, no.9, p.900-10, Sept. 1991), the commenter rates that he and M.R. Woodward (1985) implemented a system for FORTRAN-77 programs that integrates weak mutation and data flow analysis. He reports here that experiments have been carried out by them (1986), using the system to compare the error exposing ability of weak mutation, data flow, and control flow testing strategies     

Power engineering industry interaction at Clemson University

The authors present a successful model of industry/university cooperation in establishing a strong power system curriculum in both the graduate and undergraduate level. Numerous long-term and short-term research projects have been developed to satisfy the university mission and to tackle challenging problems facing the power industry. A unique structure for the Clemson University Electric Power Research Association (CUEPRA) has been established to promote electric power system research and to meet the need for a working communication link between the power industry and the academic community. The power industries involvements in the power program at Clemson University and the strategic improvements that have been accomplished in research and education are outlined     

The effect of heat on metal incorporated silica gels

Silica gel prepared under varying conditions indicated that, in addition to the pH and kind of acid, the mode of adding the solutions govern the evolution of surface area of the produced xerogel. Co-precipitation with the oxides of iron, copper, or nickel showed a marked effect in decreasing the surface area of the dry gel. Xerogels incorporated with iron oxide suffered from a sharp sintering that appeared upon heating to 900 °C. Copper oxide-incorporated silicas showed a small decrease in surface area at the same temperature. However, silica incorporated with nickel oxide seems to be resistant to heat treatment at 900 °C, and exhibits only a small change in surface area. Acid treatment of the incorporated silicas resulted in negligible variations in surface area, probably due to the low content of oxides.     

Effect of magnesium content and metal vanadate formation on the catalytic behaviour of Cu1.0−x -Mg x -V2.0 oxide/vanadate (0.0 ≤ x ≤ 1.0) system

The catalytic activity of the vapour-phase decomposition of 2-propanol over the Cu_1.0–x -Mg _x -V_2.0 oxide (0.0 x 1.0) series calcined between 500 and 1000 °C was investigated in the temperature range 165–375 °C using a flow system technique at atmospheric pressure. The catalysts were found to be selective dehydration types for 2-propanol. X-ray diffraction and scanning electron microscopy studies were used to identify the structural changes caused by the alcohol decomposition reaction. The activity and selectivity results were discussed on the basis of the electrical and/or acid-base properties of the catalysts, which not only depend on the sample composition, x, but also on its calcination temperature. A tentative reaction mechanism consistent with the obtained data has been suggested.     

Testing the performance of three-phase induction watthour meters inthe presence of harmonic distortion

Computer-based testing of a three-phase induction watthour meter in the presence of harmonic distortion is reported. Two three-phase harmonic generators produce the distorted current and voltage waveforms. Each waveform consists of prespecified harmonic magnitude and phase. Therefore, balanced or unbalanced conditions can be simulated in the testing. A fiber optic sensor is designed to convert the rotation of the disk of the meter into digital signals to be stored in an IBM PC/AT. A data acquisition system transfers the samples of current and voltage waveforms to compute the power and energy for comparison. Presented are: the computer-based harmonic generator facilities for testing, the testing procedure, and the impact of the different harmonics magnitude and phase angle on the meter's registration error     

Harmonic filter design using actual recorded data

This work presents a study of a harmonic filter design that minimizes harmonic distortion caused by harmonic sources such as drives. Several types of shunt harmonic filters are presented. The analysis includes the basic principles, the application of the Z-bus method and the economic aspects affecting the harmonic filter design. Offline steady state simulation programs, namely, V-HARM and HARMFLO, are used to model loads, to study variation of the harmonics, and to evaluate the effect of harmonic filters at various buses in the system. Several existing utility systems are used as test cases to check the performance of the filter. The major objectives in this study are (i) to improve the power factor, (ii) to reduce current and voltage distortion to standard limits, and (iii) to reduce resonance problems at other buses, if any. The transient analysis of harmonic filters using the Electromagnetic Transients Program (EMTP), which is essential to determine proper ratings of the filter components, is also reported     

Effect of harmonic distortion in reactive power measurement

The authors present the effect of harmonics on reactive power measurements and offer a new method for calculating active, reactive apparent, and residual power in nonsinusoidal conditions. The method considers common and uncommon harmonic components of voltage and current waveforms. It properly defines all power components at different harmonic frequencies, such as rotating real power, quadrature power, and the residual power (distortion). Each component is calculated correctly at different frequencies to define its physical meaning. A computer algorithm is developed to calculate all the power components for any distorted voltage and current waveforms     

A hybrid expert system for faulted section identification, faulttype classification and selection of fault location algorithms

The authors present an expert system developed in Turbo PROLOG to identify faulted sections and interpret protective apparatus operation in large interconnected power systems. This expert system is capable of identifying bus faults, line fault sections, and fault sections in the common area of a specific bus and line. Also, the expert system identifies relays or breaker malfunctions. The expert system is expanded to include real-time measurements of current and voltage phasors to classify the type of fault that the faulted section has experienced. When the faulted section is a transmission line, the expert system then selects an appropriate fault location algorithm to compute the fault location in miles. The importance of using a combination of numeric and database algorithms is emphasized     

Analysis of high-impedance fault generated signals using a Kalmanfiltering approach

High-impedance faults are accompanied by variations in the 60 Hz and harmonic components. An approach that accounts for the time-varying nature of the fundamental and harmonic components is developed. This approach is based on Kalman-filtering theory to obtain the best estimation of the time variations of the fundamental and harmonic components. Four actual recorded data sets for staged arcing fault on different types of soil are investigated by the proposed Kalman-filtering technique. The time variations of fundamental and low-order harmonic components significantly contribute to high-impedance fault detection using the features presented     

Metabolic myopathy as a cause of the exercise limitation in lung transplant recipients

BACKGROUND: Cardiopulmonary exercise (CPEx) studies of lung transplant (LTx) recipients have found low maximum oxygen consumptions because of an as yet unexplained mechanism. Although it is likely that a significant problem resides within the mitochondria, this study determines whether a defect in oxygen uptake or utilization is present. METHODS: Six LTx recipients and six age- and sex-matched, healthy control subjects were studied to assess the possibility of a mitochondrial myopathy in LTx recipients. We used standard CPEx testing in conjunction with near-infrared spectroscopy (NIRS), a noninvasive optical technique to assess peripheral oxygen uptake in exercising muscle. NIRS analyzes the absorption spectra of hemoglobin and myoglobin at 760 and 850 nm to determine the relative oxygen saturation of these compounds during exercise with respect to baseline values. Relative changes in oxygen saturation are determined from the application of Beers law to changes in absorbance to compute changes in optical density (deltaOD). The LTx recipients and control subjects performed maximal noninvasive CPEx studies with NIRS analysis of the vastus lateralis muscle. RESULTS: All subjects had a circulatory limitation to exercise. The LTx group had a significantly lower percent predicted maximum oxygen consumption than the control group (45.3%+/-14% vs 100.8%+/-15.6%, [mean +/- SD] P < .001) and earlier onset of the anaerobic threshold (30.3%+/-7.6% vs 60.3%+/-8.0% of predicted VO2max, P < .0001) The LTx recipients demonstrated a significantly smaller deltaOD at maximum exercise as determined by NIRS analysis (0.024+/-0.005 deltaOD vs 0.054+/-0.03 deltaOD, P < .05). CONCLUSIONS: LTx recipients have an impaired maximal exercise capacity because of a disorder of peripheral oxygen utilization. This may be caused by a cyclosporine-induced mitochondrial myopathy.