Showing papers by "University of Winnipeg published in 1993"
02 Oct 1993
TL;DR: It is shown that a combination of several PWM techniques offers the best solution for the drives application and that large induction motors with ratings up to 22 MVA, 7.46 kV may be supplied by the five-level inverter using presently available 4.5 kV, 3.0 kA GTO thyristors.
Abstract: The development of large induction motor drives with low torque ripple and fast dynamic response for new or retrofit applications has been limited by the device ratings and problems of series connections. This paper investigates the use of a five-level GTO voltage-sourced inverter for large induction motor drives. The advantages of such a drive are that single GTO thyristors may be used at each level, thereby avoiding the need for series connection of the thyristors. The thyristors are well protected from overvoltages by the clamping action of the DC supply capacitors. The disadvantages are that each DC level requires a separate supply, four in the case of the five-level inverter, and that the devices are not equally loaded. This paper reviews the basic operation of the five-level inverter and possible PWM voltage/frequency control techniques for the specific application of induction motor drives. The simulation results clearly show the unequal loading of the devices and the need for independent voltage supplies for the five levels. It is shown that a combination of several PWM techniques offers the best solution for the drives application. The conclusions indicate that large induction motors with ratings up to 22 MVA, 7.46 kV may be supplied by the five-level inverter using available 4.5 kV, 3.0 kA GTO thyristors. The recommended supply for such an inverter with full regenerative operation over the complete speed range is four, four-quadrant converters in a quasi-24-pulse configuration. >
289 citations
TL;DR: In this paper, it is proposed that the cognitive mechanisms underlying attachment styles are expectations about interaction with significant others, and that individuals of different attachment styles do have different expectations about likely patterns of interaction with a romantic partner in various interpersonal domains.
Abstract: It is proposed that the cognitive mechanisms underlying attachment styles are expectations about interaction with significant others. Two studies are described that assessed these relational schemata. The first study revealed that individuals of different attachment styles do have different expectations about likely patterns of interaction with a romantic partner in various interpersonal domains. The second study demonstrated the utility of the lexical decision task for examining interpersonal expectancies. When given a related context, secure subjects were quicker to identify words representing positive interpersonal outcomes, whereas insecure subjects were quicker to identify negative outcome words. Methodological and conceptual implications of a relational schema approach to attachment styles are discussed.
255 citations
TL;DR: The results from factor analyses demonstrated that the BAI has two factors, corresponding to cognitive and somatic symptoms as discussed by the authors, and that BAI items were distinguishable from BDI items, suggesting that the symptoms measured in the two scales are not entirely overlapping.
Abstract: This study sought to provide information on the Beck Anxiety Inventory (BAI) with respect to psychometric properties, gender differences, and relation to depression. A sample of 291 psychiatric patients completed the BAI, and a subsample of 251 completed the Beck Depression Inventory (BDI). The results from factor analyses demonstrated that the BAI has 2 factors, corresponding to cognitive and somatic symptoms. Although men and women did not differ in terms of factor structures, they did differ on mean levels of cognitive and somatic symptom scores and on total BAI scores. Finally, the authors found that BAI items were distinguishable from BDI items, suggesting that the symptoms measured in the two scales are not entirely overlapping
192 citations
Journal Article•
TL;DR: Early data from hydroelectric reservoirs in northern Canada support this hypothesis and show that both upland forests and peatlands are sites of intense microbial decomposition and greenhouse-gas production when they become covered with water as mentioned in this paper.
Abstract: Estimates suggest that, per unit of energy produced, greenhouse-gas flux to the atmosphere from some hydroelectric reservoirs may be significant compared to greenhouse-gas emission by fossil-fuelled electricity generation. Greenhouse gases (CO[sub 2] and CH[sub 4]) are produced during bacterial decomposition of flooded peat and forest biomass. The amount emitted will be positively related to the area flooded. Early data from hydroelectric reservoirs in northern Canada support this hypothesis. Our hypothesis is based primarily on two of our past studies which show that both upland forests and peatlands are sites of intense microbial decomposition and greenhouse-gas production when they become covered with water. During the summer of 1992, the first preliminary data were obtained that support our hypothesis. At 12 sampling locations on the LaGrande II-Boyd[sub S]akami Reservoir complex in northern Quebec, both the CO[sub 2] and CH[sub 4] were found to be evading to the atmosphere. CO[sub 2] concentrations were 2-3 times above atmospheric equilibrium at all sampling sites. This is in contrast to two large lakes, Nipigon and Superior, where CO[sub 2] was being absorbed from the atmosphere throughout the ice-free season. Surface CH[sub 4] concentrations were 0.05-1.1 [mu]mol L[sup -1] with most sites having concentrations higher than in natural, stratified Canadian shield lakes. Further measurements are required to determine annual fluxes. (19 refs., 3 figs., 2 tabs.)
181 citations
TL;DR: Different fuzzy-set oriented computational models of neurons are introduced and different topologies of neural networks put together with the use of these neurons are proposed to contribute significantly toward enhancements in learning processes in the network and substantially facilitates its interpretation.
Abstract: We will introduce and study different fuzzy-set oriented computational models of neurons. The generic topologies of the neurons emerging there are significantly influenced by basic logic operators(AND, OR, NOT) encountered in the theory of fuzzy sets. The logical flavor of the proposed constructs is expressed in terms of operators used in their formalization and a way of their superposition in the neurons. The two broad categories of neurons embrace basic aggregation neurons (named AND and OR neurons) and referential processing units (such as matching, dominance, inclusion neurons). The specific features of the neurons are flexibly modeled with the aid of triangular norms. The inhibitory and excitatory characteristics are captured by embodying direct and complemented (negated) input signals. We will propose various topologies of neural networks put together with the use of these neurons and demonstrate straightforward relationships coming off between the problem specificity and the resulting architecture of the network. This limpid way of mapping the domain knowledge onto the structure of the network contributes significantly toward enhancements in learning processes in the network and substantially facilitates its interpretation. >
167 citations
TL;DR: MR imaging with dynamic gadolinium enhancement and fat suppression is a promising tool in the investigation of islet cell tumors.
Abstract: Ten patients with 11 islet cell tumors underwent dynamic contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging within a 1-month period. MR imaging depicted all 11 tumors, and CT depicted seven of the 11 tumors. CT did not depict four of seven tumors that measured 2.5 cm in diameter or less. Islet cell tumors had low signal intensity on T1-weighted fat-suppressed MR images, and gastrinomas were best shown with this technique. Two of three insulinomas less than 1.5 cm in diameter were best shown on dynamic contrast-enhanced fast low-angle shot (FLASH) images as uniform areas of high signal intensity. Hepatic metastases were seen in five patients and showed peripheral ringlike enhancement best demonstrated on dynamic gadolinium-enhanced FLASH images. Hepatic lesions were most conspicuous on T2-weighted fat-suppressed spin-echo images. MR imaging with dynamic gadolinium enhancement and fat suppression is a promising tool in the investigation of islet cell tumors.
153 citations
TL;DR: The results suggest that in vivo 1H magnetic resonance spectroscopy may aid in diagnosing the extent of chronic localized encephalitis and the severity of hippocampal gliosis.
Abstract: We used high-resolution 1 H magnetic resonance spectroscopy to determine the concentrations of several metabolites (lactate, alanine, N -acetylaspartate [NAA], γ-aminobutyrate, glutamate, aspartate, creatine, cholines, taurine, inositol, and succinate) in tissue from patients undergoing surgical treatment of intractable epilepsy, and correlated the metabolite profiles with the results of histopathologic analysis of the excised tissue. We found no differences in metabolite levels for tissue from actively spiking or nonspiking neocortical sites in temporal lobe epilepsy patients. In neocortical tissue from patients with chronic localized encephalitis (Rasmussen9s encephalitis), the metabolite concentrations varied with the severity and extent of the encephalitis. In tissue showing mild encephalitis and mild histologic abnormalities, the metabolite levels differed little from those found for nonencephalitic neocortical tissue. Tissue showing marked abnormalities and extensive encephalitis had decreased NAA, glutamate, cholines, and inositol. In hippocampal tissue from temporal lobe epilepsy patients, the levels of NAA, glutamate, and aspartate were lower and the levels of alanine, taurine, and inositol were higher than in neocortical tissue from the same patients. The decrease in the levels of NAA and glutamate was greater in gliotic hippocampal tissue. The results suggest that in vivo 1 H magnetic resonance spectroscopy may aid in diagnosing the extent of chronic localized encephalitis and the severity of hippocampal gliosis.
83 citations
TL;DR: This article investigated the association between dimensions of perfectionism and specific fears and found that self-oriented and socially prescribed perfectionism were associated with specific fears about failure, making mistakes, losing control, and feeling angry.
80 citations
TL;DR: The findings are as follows: Among first generation male and second generation male, the gender pay gap among first generation males in Winnipeg is higher than in other developed countries.
Abstract: Data for this study were collected using a questionnaire method in Winnipeg in 1986 and analyzed using multiple regression technique. The findings are as follows: Among first generation male and fe...
60 citations
19 Apr 1993
TL;DR: In this paper, a 3-layer backpropagation model was used to learn the relationship between 86 inputs, which are believed to have significant effects on the loads, and 24 outputs: one for each hourly load of the day.
Abstract: This paper describes the application of an artificial neural network to short term load forecasting. One of the most popular artificial neural network models, the 3-layer backpropagation model, is used to learn the relationship between 86 inputs, which are believed to have significant effects on the loads, and 24 outputs: one for each hourly load of the day. Historical data collected over a period of 2 years (e.g. calendar years 1989 and 1990) is used to train the proposed ANN network. The results of the proposed ANN networks have been compared to those of the present system (multiple linear regression) and show an improved forecast capability. >
56 citations
TL;DR: A simple analysis of the information for depth present in optic flow is given and the psychophysical results for depth recovery from motion are reviewed.
Abstract: The field of depth recovery from optic flow has recently experienced much growth, both on the theoretical and on the empirical fronts. Unfortunately, the theoretical results are not as widely known to perception workers as they might be. This article gives a simple analysis of the information for depth present in optic flow. It also reviews the psychophysical results for depth recovery from motion. These results are discussed with reference to the theoretical analysis and to relevant computer algorithms for depth recovery.
28 Mar 1993
TL;DR: The implementation of artificial neural networks using stochastic arithmetic capable of in situ learning is described and the performance of this architecture is demonstrated by two examples.
Abstract: The implementation of artificial neural networks using stochastic arithmetic capable of in situ learning is described. Stochastic arithmetic uses values encoded as a pulse density, and allows addition, multiplication, and the nonlinearity to be implemented in a very small amount of digital hardware. A VLSI implementation of such a network is capable of processing 100000 training vectors per second. The performance of this architecture is demonstrated by two examples. >
28 Jun 1993
TL;DR: In this paper, a novel radiating element is presented which can provide simultaneously a large bandwidth and high gain, and it consists of four identical patches uniformly displayed within a rectangular aperture (2*2), and fed electromagnetically by a driven patch etched on a lower substrate.
Abstract: A novel radiating element is presented which can provide simultaneously a large bandwidth and high gain. It consists of four identical patches uniformly displayed within a rectangular aperture (2*2), and fed electromagnetically by a driven patch etched on a lower substrate. It is shown that a good coupling with the parasitic patches is obtained, causing a large bandwidth, and that the resonance modes of each patch are excited in phase, giving a high gain. Its structural simplicity and superior performance make this element an attractive candidate for large phase arrays. >
TL;DR: CMOS circuits implementing an analog neural network with on-chip deterministic Boltzmann learning (DBL) and capacitive synaptic weight storage have been designed, fabricated, and tested and indicate that deterministicboltzmann ANNs can be implemented efficiently using analog CMOS circuitry.
Abstract: CMOS circuits implementing an analog neural network (ANN) with on-chip deterministic Boltzmann learning (DBL) and capacitive synaptic weight storage have been designed, fabricated, and tested. Weights are refreshed by periodic repetition of the training data. The circuits were used to build a 12-neuron, 132-synapse ANN that performed well in a variety of learning experiments, including a 36-input to 4-output mapping problem. Adaptive systems such as those described here can compensate for imperfections in the components from which they are constructed and therefore can be built using simple silicon area-efficient analog circuits. The test results indicate that deterministic Boltzmann ANNs can be implemented efficiently using analog CMOS circuitry. >
TL;DR: In this article, it is argued that recent changes in families require us to rethink the standard model of family change, initiated by Burgess, as disorganization/reorganization.
Abstract: It is argued here that recent changes in families require us to rethink the standard model of family change, initiated by Burgess, as disorganization/reorganization. The dominant image of family life in standard sociological theory was summarized by Burgess in his influential definition of the family as “a unity of interacting persons.” Yet Burgess's studies of families in the 1920s, in fact, revealed two contrasting patterns of relationships. He referred to them as “the highly integrated family” and the “unintegrated or loosely integrated family.” Burgess's devalorization of the latter is described as being typical of theories of the modern family. In the 1980s and 1990s, sociological attention has increasingly turned toward concepts of divergence and difference. It is recommended that these issues be brought into sharper focus in theories of the postmodern family. Some suggestions are made for a research agenda from this emergent perspective.
17 May 1993
TL;DR: The performance of the discrete wavelet transform in terms of the bit rates and signal quality is comparable to that for other techniques such as the discrete cosine transform for images and code-excited linear predictive coding for speech, but with much less computational burden.
Abstract: The authors consider time-frequency multiresolution analysis based on wavelets, as it applies to speech/audio and image/video signal compression. They compare the wavelet analysis to the traditional short-window techniques used in signal compression. The performance of the discrete wavelet transform in terms of the bit rates and signal quality is comparable to that for other techniques such as the discrete cosine transform (DCT) for images and code-excited linear predictive coding (CELP) for speech, but with much less computational burden. Experiments with an image and Daubechies's four-coefficient wavelet show that truncation of wavelet coefficients as high as 90% still produces 30-dB peak signal-to-noise ratio (PSNR) quality. This is better than DCT. In an experiment on a male spoken sentence, the scheme reaches a 12.82-dB segmental signal-to-noise ratio (SEGSNR) at a rate of less than 4.8 kb/s. In comparison, the state-of-the-art CELP coding at 4.8 kbit/s can attain SEGSNR of 10-13 dB. Other experiments with images and Haar two-coefficient wavelet are also highlighted. >
TL;DR: In this article, a non-contact scanned probe potential measurement technique for integrated circuits is presented, where local potentials are extracted by sensing the electrostatic force between an energized probe and the circuit being tested.
Abstract: A high-resolution non-contact scanned probe potential measurement technique for integrated circuits is presented. Local potentials are extracted by sensing the electrostatic force between an energised probe and the circuit being tested. Using a nulling method, accurate magnitude measurement of high frequency signals can be performed without complex calibration.
TL;DR: Investigation of the relationship between panic attacks and awareness for cardiac sensations using an objective heartbeat discrimination procedure indicated that panic attacks were not related to enhanced interoceptive acuity for cardiac sensation, either at rest or following hyperventilation.
TL;DR: Patients who had attempted suicide, when compared to non-suicide attempters, were more likely to be classified as having PD, and be non-married, while IP and NP groups did not differ on any of the relevant variables.
01 Mar 1993
TL;DR: In this article, a novel algorithm for calculating high-voltage direct-current (HVDC) fields in the presence of corona and strong winds based on the boundary element-method (BEM) is presented.
Abstract: A novel algorithm for calculating high-voltage direct-current (HVDC) fields in the presence of corona and strong winds based on the boundary element-method (BEM) is presented. The algorithm uses an auxiliary Poisson's equation for updating the space-charge density during the iteration. The iteration process is convergent for wind velocities tested up to 12-m/s. The algorithm can be used for the calculation of ionized fields associated with bipolar HVDC power transmission lines, with some modifications. >
TL;DR: A nonperturbative ansatz is obtained for the wave functional of a black hole interacting with its surroundings by suitably relaxing the boundary conditions.
Abstract: A solvable two-dimensional conformally invariant midisuperspace model for black holes is obtained by imposing spherical symmetry in four-dimensional conformally invariant Einstein gravity The Wheeler-DeWitt equation for the theory is solved exactly to obtain the unique quantum wave functional for an isolated black hole with a fixed mass By suitably relaxing the boundary conditions, a nonperturbative ansatz is obtained for the wave functional of a black hole interacting with its surroundings
TL;DR: In this paper, a speech act analysis of presumption is presented, using the framework of a dialogue in which two parties reason together, where the burden of proof lies not on the proponent to prove, but on the respondent to rebut.
Abstract: This paper presents a speech act analysis of presumption, using the framework of a dialogue in which two parties reason together. In the speech act of presumption, as opposed to that of assertion, the burden of proof resides not on the proponent to prove, but on the respondent to rebut. Some connections of this account with nonmonotonic reasoning and informal fallacies in argumentation are explored.
TL;DR: Results suggest that both spontaneous and cued panic attacks may play a prominent role in the development of anxiety sensitivity.
TL;DR: The most common household financial strategy among Canadian couples today is that of flexible shares as discussed by the authors, which is suggested as evidence of a shift in the form of companionate marriage toward greater equality of economic agency.
Abstract: In Canada, there has been a marked increase in the relative frequency of dual earner families, and especially of dual career families, compared to breadwinner/homemaker families. Effects of this change on the handling of incomes inside the household are examined here. In this paper, quantitative survey data and qualitative data on strategies of financial management are described and analyzed for co-resident couples in Winnipeg. Findings are presented on control over income, financial possession, and access to household money. These findings are interpreted as evidence of a shift in the form of companionate marriage toward greater equality of economic agency. It is suggested that the most common household financial strategy among Canadian couples today is that of flexible shares.
09 May 1993
TL;DR: Preliminary simulation result are very promising and demonstrate that the basic technique may be quite practical, and is intended for use in a built-in test mode.
Abstract: A novel circuit for I/sub ddq/ monitoring is presented. The circuit is based on current mode signaling and is intended for use in a built-in test mode. A test chip has been fabricated in 1.2 micron CMOS. Preliminary simulation result are very promising and demonstrate that the basic technique may be quite practical.
TL;DR: Post-ischemic hyperglycemia resulted in delayed recovery of tissue pH in all groups and of PCr and ATP in animals hyperglycemic throughout the experiment, and insulin administration immediately following ischemia increased the rate of recovery of pH, ATP and PCr inhyperglycemic animals.
TL;DR: Rice originating from Saskatchewan and northern Manitoba contained significantly higher copper concentrations than samples from Ontario and southeastern Manitoba, and larger and heavier grains contained higher lead concentrations per unit weight.
Abstract: Samples of wild rice grains available for sale in Manitoba, Canada contained <0.01–6.2 μg/g cadmium, <0.01–6.7 μg/g lead, and 1.6–14.4 wg/g copper. Rice originating from Saskatchewan and northern Manitoba contained significantly higher copper concentrations than samples from Ontario and southeastern Manitoba. Larger and heavier grains contained higher lead concentrations per unit weight. Mean content of all three metals per individual grain was exponentially correlated with grain size and weight. Total soluble carbohydrate and soluble protein concentrations were negatively correlated with copper concentrations.
TL;DR: In this article, the authors examined the growth of government expenditures in Canadian provinces and found that the private sector share of the Provincial Gross Domestic Product (PGDP), capacity utilization and factors such as federal transfer payments to the provincial governments best explain the growth in expenditure at the provincial level.
Abstract: Most empirical studies have sought to explain the overall growth of the total government expenditures. Few studies have focused on the growth of spending at the provincial level. This article seeks to fill the gap. It examines the growth of government expenditures in Canadian provinces. Data spanning the past three decades are used to explain the growth of provincial government expenditures in Canada and to test alternative hypotheses. From a basic general theoretical model, three empirical models are developed and tested. It is concluded that the growth of the private sector share of the Provincial Gross Domestic Product (PGDP), capacity utilization and factors such as federal transfer payments to the provincial governments best explain the growth in expenditure at the provincial level. The expenditure policies of provincial governments are found to be independent of the political stance of the political parties in power. Estimated short-run and long-run ‘income’ elasticities of provincial government exp...
TL;DR: In this paper, gas sparging was conducted in lake enclosures previously treated with [4,6[sup 3]-H]-2,3,7,8-tetrachlorodibenzofuran (TCDF) to determine the fugacity or dissolved concentration of this hydrophobic contaminant under field conditions.
Abstract: Gas sparging was conducted in lake enclosures previously treated with [4,6[sup 3]-H]-2,3,7,8-tetrachlorodibenzofuran (TCDF) to determine the fugacity or dissolved concentration of this hydrophobic contaminant under the field conditions. Using a Henry's law constant for TCDF of 1.7[+-]0.8Pa[times]m[sup 3]/mol, measured experimentally by gas sparging, apparent dissolved TCDF concentrations of 7 to 22 pg/L were determined. These results were 100 times greater than concentrations of TCDF obtained by extraction of water samples from the same enclosures with dichloromethane. TCDF was found to be highly associated with naturally occurring particles in the water column, with 40% of sorbed TCDF associated with the 0.1- to 3-[mu]m size fraction. The results are interpreted in light of previous reports that indicate that bubbles are effective scavengers of bacteria and particulates in natural waters, transporting these solids across the water/air interface as bubbles burst at the water surface. In the laboratory addition of a yeast suspension increased the amount of TCDF sparged from aqueous solutions, confirming that particle-mediated movement of highly sorbed contaminants can influence apparent water concentrations measured by gas sparging on natural waters.
TL;DR: In this paper, the authors developed an empirically derived multivariate taxonomy of shoplifters by cluster analysis, including demographic characteristics, past history, psychosocial stressors, and purpose in life measures.
Abstract: The purpose of this study was to develop an empirically derived multivariate taxonomy of shoplifters by cluster analysis. Previously collected data from 75 suspected shoplifters, including demographic characteristics, past history, psychosocial stressors, and purpose in life measures as defined by the Purpose in Life (PIL), and Seeking of Noetic Goals (SONG) tests were analyzed. The results of cluster analysis indicate that shoplifters are a heterogeneous population consisting of a least four subgroups. Implications for treatment are discussed.