Showing papers by "University of Windsor published in 1994"

Effect of microstructure (particulate size and volume fraction) and counterface material on the sliding wear resistance of particulate-reinforced aluminum matrix composites

Abstract: The effects of microstructure (namely, particulate volume fraction and particulate size) and the counterface materials on the dry-sliding wear resistance of the aluminum matrix composites 2014A1-SiC and 6061Al-Al2O3 were studied. Experiments were performed within a load range of 0.9 to 350 N at a constant sliding velocity of 0.2 ms-1. Two types of counterface materials, SAE 52100 bearing steel and mullite, were used. At low loads, where particles act as loadbearing constituents, the wear resistance of the 2014A1 reinforced with 15.8 µm diameter SiC was superior to that of the alloy with the same volume fraction of SiC but with 2.4 µm diameter. The wear rates of the composites worn against a steel slider were lower compared with those worn against a mullite slider because of the formation of iron-rich layers that act asin situ solid lubricants in the former case. With increasing the applied load, SiC and A12O3 particles fractured and the wear rates of the composites increased to levels comparable to those of unreinforced matrix alloys. The transition to this regime was delayed to higher loads in the composites with a higher volume percentage of particles. Concurrent with particle fracture, large strains and strain gradients were generated within the aluminum layers adjacent to contact surfaces. This led to the subsurface crack growth and delamination. Because the particles and interfaces provided preferential sites for subsurface crack initiation and growth and because of the propensity of the broken particles to act as third-body abrasive elements at the contact surfaces, no improvement of the wear resistance was observed in the composites in this regime relative to unreinforced aluminum alloys. A second transition, to severe wear, occurred at higher loads when the contact surface temperature exceeded a critical value. The transition loads (and temperatures) were higher in the composites. The alloys with higher volume fraction of reinforcement provided better resistance to severe wear. Wearing the materials against a mullite counterface, which has a smaller thermal conductivity than a counterface made of steel, led to the occurrence of severe wear at lower loads.

The Importance of Product Country of Origin

Abstract: Uses conjoint analysis to investigate the relative importance of the country of origin of a product to consumers in the United States, Canada, Germany and The Netherlands. It was found that the country of origin of a product was one of the two or three most important attributes in preference evaluation. Across the four countries and the two product categories studied, the importance weight assigned to the country‐of‐origin factor ranged from 18 to 29 per cent, a level of importance that was often equal to or greater than that assigned to the brand name, price and other intrinsic and extrinsic attributes. Respondents in each country preferred domestically‐made products foremost, followed by products made in other developed countries and, lastly, products made in developing countries.

A fuzzy neural network and its application to pattern recognition

Abstract: Defines four types of fuzzy neurons and proposes the structure of a four-layer feedforward fuzzy neural network (FNN) and its associated learning algorithm. The proposed four-layer FNN performs well when used to recognize shifted and distorted training patterns. When an input pattern is provided, the network first fuzzifies this pattern and then computes the similarities of this pattern to all of the learned patterns. The network then reaches a conclusion by selecting the learned pattern with the highest similarity and gives a nonfuzzy output. The 26 English alphabets and the 10 Arabic numerals, each represented by 16/spl times/16 pixels, were used as original training patterns. In the simulation experiments, the original 36 exemplar patterns were shifted in eight directions by 1 pixel (6.25% to 8.84%) and 2 pixels (12.5% to 17.68%). After the FNN has been trained by the 36 exemplar patterns, the FNN can recall all of the learned patterns with 100% recognition rate. It can also recognize patterns shifted by 1 pixel in eight directions with 100% recognition rate and patterns shifted by 2 pixels in eight directions with an average recognition rate of 92.01%. After the FNN has been trained by the 36 exemplar patterns and 72 shifted patterns, it can recognize patterns shifted by 1 pixel with 100% recognition rate and patterns shifted by 2 pixels with an average recognition rate of 98.61%. The authors have also tested the FNN with 10 kinds of distorted patterns for each of the 36 exemplars. The FNN can recognize all of the distorted patterns with 100% recognition rate. The proposed FNN can also be adapted for applications in some other pattern recognition problems. >

Principal Identifying Features of the Syndrome of Nonverbal Learning Disabilities in Children

Abstract: The identifying features of the syndrome of nonverbal learning disabilities (NLD) were examined with a view to determining their relative discriminant validity A stepwise linear discriminant function analysis of children with NLD (n = 29), children with reading and spelling disabilities (Group R-S; n = 27), and a group of nonclinical children (NC; n = 27) on 15 neuropsychological variables yielded a subset of scores on four tests (Target Test; Trail Making Test, Part B; Tactual Performance Test; and Grooved Pegboard Test) that accurately (> 95%) discriminated the NLD group from the R-S and NC subjects Of the neuropsychological features of NLD described by Rourke (1987, 1988b, 1989), deficits in visual-perceptual-organizational psychomotor coordination and complex tactile-perceptual skills appeared to be most representative (in the sense of most discriminative) of the NDL syndrome in the children examined These are also the dimensions that are considered to be "primary" in the NLD model (Rourke, 1989) Replication of these results, employing children with other clinical disorders, is necessary

Coping with transition: a study of layoff survivors

Abstract: This study examined the determinants and consequences of survivors' coping responses to a recent workforce reduction involving permanent layoffs. The participants consisted of 200 unionized technicians in the telecommunications industry. Survivors with high optimistic predispositions and a strong sense of mastery were more likely to engage in control-oriented coping. Perceived threat of job loss was positively related to the use of both control and escape coping whereas sense of powerlessness was negatively related to the use of control coping. Control coping was associated with positive outcomes and escape coping with negative outcomes. Coping had both additive and interactive effects on the outcome variables. The implications of these findings for management are discussed.

Chemical changes at the surface of RTV silicone rubber coatings on insulators during dry-band arcing

Abstract: Under wet and contaminated conditions dry band arcing occurs on the surface of HV outdoor insulators coated with room temperature vulcanizing (RTV) silicone rubber. The thermal impact of the arcing on the surface of the RTV causes chemical changes. The gradual loss of hydrophobicity due to dry band arcing is of considerable concern because it results in a reduction of the withstand voltage and subsequent failure of the insulator and power outage. In this study the RTV coatings were subjected simultaneously to salt-fog and electrical stress. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and electron spectroscopy for chemical analysis (ESCA) were then employed to investigate the chemical changes. Possible chemical reactions and processes occurring under dry band arcing are suggested. The results of ATR-FTIR and ESCA indicate the formation of low molecular weight polydimethylsiloxane (PDMS), the reduction in the surface density of CH3 groups and crosslinking of the PDMS backbone chains at the surface. Chemical derivative analysis was also carried out to further elucidate the chemical changes on the surface of RTV coating. >

Visible light photochemical release of nitric oxide from S-nitrosoglutathione: potential photochemotherapeutic applications.

Abstract: Some aspects of the physiological role of NO may be mediated by stable NO-carriers such as S-nitrosoglutathione and related S-nitrosothiols. In this report we show that irradiation of S-nitrosoglutathione at either absorption band (lambda max = 340 nm or 545 nm) results in the release of nitric oxide. Photolysis of S-nitrosoglutathione at 545 nm exhibited a quantum yield of 0.056 +/- 0.002 and was best approximated by a first-order process with kobs = 4.9 x 10(-7) +/- 0.3 x 10(-7) s-1. The photolytic release of NO from S-nitrosoglutathione resulted in an enhanced cytotoxic effect of S-nitrosoglutathione on HL-60 leukemia cells. That the cytotoxic effect of S-nitrosoglutathione was diminished by the addition of oxyhemoglobin strongly suggests that NO is the cytotoxic species. The finding that NO can be readily liberated from S-nitrosoglutathione by visible radiation indicates that the photochemical properties of this compound in the visible spectrum must be considered in order to obtain meaningful data as to its physiological role and the S-nitrosoglutathione and related compounds may find use as photochemotherapeutic agents.

Testing the Goodness of Fit of a Parametric Density Function by Kernel Method

Abstract: Let F denote a distribution function defined on the probability space (Ω,,P), which is absolutely continuous with respect to the Lebesgue measure in Rd with probability density function f. Let f0(·,β) be a parametric density function that depends on an unknown p × 1 vector β. In this paper, we consider tests of the goodness-of-fit of f0(·,β) for f(·) for some β based on (i) the integrated squared difference between a kernel estimate of f(·) and the quasimaximum likelihood estimate of f0(·,β) denoted by In and (ii) the integrated squared difference between a kernel estimate of f(·) and the corresponding kernel smoothed estimate of f0(·, β) denoted by Jn. It is shown in this paper that the amount of smoothing applied to the data in constructing the kernel estimate of f(·) determines the form of the test statistic based on In. For each test developed, we also examine its asymptotic properties including consistency and the local power property. In particular, we show that tests developed in this paper, except the first one, are more powerful than the Kolmogorov-Smirnov test under the sequence of local alternatives introduced in Rosenblatt [12], although they are less powerful than the Kolmogorov-Smirnov test under the sequence of Pitman alternatives. A small simulation study is carried out to examine the finite sample performance of one of these tests.

A new technique for loss reduction using compensating capacitors applied to distribution systems with varying load condition

Abstract: A new method based on a heuristic technique for reactive loss reduction in distribution network is presented. This method allocates capacitors to certain nodes (sensitive nodes) which are selected by first identifying the branch which has the largest losses due to reactive power. Then, the node therein, which has the largest reactive power is selected. The capacitor rating is determined by differentiating the system losses with respect to the load connected to that node. The compensating capacitors are placed at these optimal locations with appropriate VAr ratings to achieve maximum benefits in dollar savings. The variation of the load during the year is considered. The capital and installation costs of the capacitors are also taken into account. This method is applied to a 38 feeder distribution system of 27.6 kV, 560 MVA of the city of Windsor, Ontario, resulting in annual saving of about CAN $145000 after amortizing the capital and installation costs of applying the compensating capacitors, and using a figure for the cost of energy of 1.986 cents per kWh. >

Purpose in life and outcome of treatment for alcohol dependence.

Abstract: A number of studies have linked the development of substance abuse problems to a lack of purpose or meaning in life, and a few studies have demonstrated an increase in sense of life purpose through substance abuse treatment programmes. The present study extended past research by examining the relationship of purpose in life to treatment outcome assessed three months after completion of treatment. The subject sample comprised 131 people in in-patient treatment programmes or awaiting treatment for alcoholism (in some cases in addition to other drug addictions). Consistent with previous research, the mean Purpose in Life Test (PIL) score before treatment was significantly below the normal range and the mean PIL score at the end of in-patient treatment was within the normal range. Furthermore, the PIL score at the end of treatment was predictive of changes in intimate relationships and health at follow-up. It was also predictive of follow-up drinking/drug use status. However, the pattern of prediction differed in the two treatment groups. Post-treatment PIL score was a positive predictor of improvement in a skill-based treatment centre, and a negative predictor in a more authoritarian, confrontation-based programme. The distinction between internally and externally derived senses of meaning is presented as one possible explanation of these findings.

Biological assessment of aquatic pollution: a review, with emphasis on plants as biomonitors*

Abstract: In a number of disciplines including ecology, ecotoxicology, water quality management, water resource management, fishery biology etc., there is significant interest in the testing of new materials, environmental samples (of water or sediments) and specific sites, in terms of their effects on biota. In the first instance, we consider various sources of aquatic pollution, sources typically associated with developed areas of the world. Historically, much water quality assessment has been performed by researchers with a background in chemistry or engineering, thus chemical analysis was a dominant form of assessment. However, chemical analyses, particularly of such materials as organochlorines and polyaromatic hydrocarbons can be expensive, and local environmental factors may cause the actual exposure of an organism to be little correlated with chemical concentrations in the surrounding water or sediments. To a large extent toxicity testing has proceeded independently of environmental quality assessment in situ, and the work has been done by different, and differently-trained researchers. Here we attempt to bring together the various forms of biological assessment of aquatic pollution, because in our opinion it is worth developing a coherent framework for the application of this powerful tool. Biotic assessment in its most primitive form involves the simple tracking of mortality in exposed organisms. However, in most natural environments it is extended, chronic exposure to contaminants that has the most wide-ranging and irreversible repercussions--thus measures of sub-lethal impairment are favoured. From an ecological standpoint, it is most valuable to assess ecological effects by direct study of in situ contaminant body burdens and impairment of growth and reproduction compared with 'clean' sites. A distinction is made here between bioindication and biomonitoring, and a case is made for including aquatic macrophytes (angiosperms) in studies of contaminant levels and effects in the biota. It is apparent that there is a concurrent need for laboratory-based testing of new industrial by-products before any are released in the environment, and such studies should aid the investigation of mechanisms and modes of toxicity, but environmental assessment, and tracking of improvements in environmental quality are most effectively achieved by active biomonitoring experiments.

An image processing system for locating craniofacial landmarks

Abstract: A new automatic target recognition algorithm has been developed to extract craniofacial landmarks from lateral skull X-rays (cephalograms). The locations of these landmarks are used by orthodontists in what is referred to as a cephalometric evaluation. The evaluation assists in the diagnosis of anomalies and in the monitoring of treatments. The algorithm is based on gray-scale mathematical morphology. A statistical approach to training was used to overcome subtle differences in skeletal topographies. Decomposition was used to desensitize the algorithm to size differences. A system was trained to locate 20 landmarks. Tests on 40 X-rays showed an 85% recognition rate on average. >

Diagenesis and formation water chemistry of Triassic reservoir sandstones from southern Tunisia

Abstract: The fluvial Triassic reservoir subarkoses and arkoses (2409·5–2519·45 m) of the El Borma oilfield, southern Tunisia, were subjected to cementation by haematite, anatase, infiltrated clays, kaolinite and K-feldspar at shallow burial depths from meteoric waters. Subsequently, basinal brines controlled the diagenetic evolution of the sandstones and resulted initially in the precipitation of quartz overgrowths, magnesian siderite, minor ferroan magnesite and anhydrite. The enrichment of siderite in 12C isotope (δ13CPDB= - 14·5 to - 9‰) results from derivation of carbon from the thermal decarboxylation of organic matter. During further burial, the precipitation of dickite and pervasive transformation of kaolinite into dickite occurred, followed by the formation of microcrystalline K-feldspar and quartz, chlorite and illite, prior to the emplacement of oil. Present day formation waters are Na-Ca-Cl brines evolved by the evaporation of seawater and water/mineral interaction and are in equilibrium with the deep burial (≤ 3·1 km) minerals. These waters are suggested to be derived from the underlying Silurian and Devonian dolomitic mudstones.

Frequency ratios and the perception of tone patterns

Abstract: We quantified the relative simplicity of frequency ratios and reanalyzed data from several studies on the perception of simultaneous and sequential tones. Simplicity of frequency ratios accounted for judgments of consonance and dissonance and for judgments of similarity across a wide range of tasks and listeners. It also accounted for the relative ease of discriminating tone patterns by musically experienced and inexperienced listeners. These findings confirm the generality of previous suggestions of perceptual processing advantages for pairs of tones related by simple frequency ratios.

Lamb shifts and hyperfine structure in 6Li+ and 7Li+: Theory and experiment.

Abstract: High-precision laser-resonance measurements accurate to \ifmmode\pm\else\textpm\fi{}0.5 MHz or better are reported for transitions among the 1s2s $^{3}$${\mathit{S}}_{1--}$1s2p $^{3}$${\mathit{P}}_{\mathit{J}}$ hyperfine manifolds for each of J=0, 1, and 2 in both $^{6}\mathrm{Li}^{+}$ and $^{7}\mathrm{Li}^{+}$. A detailed analysis of hyperfine structure is performed for both the S and P states, using newly calculated values for the magnetic dipole and electric quadrupole coupling constants, and the hyperfine shifts subtracted from the measurements. The resulting transition frequencies are then analyzed on three different levels. First, the isotope shifts in the fine-structure splittings are calculated from the relativistic reduced mass and recoil terms in the Breit interaction, and compared with experiment at the \ifmmode\pm\else\textpm\fi{}0.5-MHz level of accuracy. This comparison is particularly significant because J-independent theoretical uncertainties reduce through cancellation to the \ifmmode\pm\else\textpm\fi{}0.01-MHz level. Second, the isotope shifts in the full transition frequencies are used to deduce the difference in rms nuclear radii.The result is ${\mathit{R}}_{\mathrm{rms}}$${(}^{6}$Li)-${\mathit{R}}_{\mathrm{rms}}$${(}^{7}$Li)=0.15\ifmmode\pm\else\textpm\fi{}0.01 fm, in agreement with nuclear scattering data, but with substantially improved accuracy. Third, high-precision calculations of the low-order non-QED contributions to the transition frequencies are subtracted from the measurements to obtain the residual QED shifts. The isotope-averaged and spin-averaged effective shift for $^{7}\mathrm{Li}^{+}$ is 37 429.40\ifmmode\pm\else\textpm\fi{}0.39 MHz, with an additional uncertainty of \ifmmode\pm\else\textpm\fi{}1.5 MHz due to finite nuclear size corrections. The accuracy of 11 parts per million is the best two-electron Lamb shift measurement in the literature, and is comparable to the accuracies achieved in hydrogen. Theoretical contributions to the two-electron Lamb shift are discussed, including terms of order (\ensuremath{\alpha}Z${)}^{4}$ recently obtained by Chen, Cheng, and Johnson [Phys. Rev. A 47, 3692 (1993)], and the results used to extract a QED shift for the 2 $^{3}$${\mathit{S}}_{1}$ state. The result of 30 254\ifmmode\pm\else\textpm\fi{}12 MHz is shown to be in good accord with theory (30 250\ifmmode\pm\else\textpm\fi{}30 MHz) when two-electron corrections to the Bethe logarithm are taken into account by a 1/Z expansion method.

Suicide as Social Logic.

Abstract: Although suicide is not viewed as a mental disorder per se, it is viewed by many if not most clinicians, researchers, and lay people as a real or natural symptom of depression. It is at least most typically seen as the unfortunate, severe, yet logical end result of a chain of negative self-appraisals, negative events, and hopelessness. Extending an approach articulated by the early French sociologist Gabriel Tarde, in this paper I argue that suicide is merely an idea, albeit a very bad one, having more in common with societal beliefs and norms regarding such things as divorce, abortion, sex, politics, consumer behavior, and fashion. I make a sharp contrast between perturbation and lethality, concepts central to Edwin S. Shneidman's theory of suicide. Evidence supportive of suicide as an idea is discussed based on what we are learning from the study of history and culture, and about contagion/cluster phenomena, media/communication, and choice of method. It is suggested that certain individuals are more vulnerable to incorporate the idea and act of suicide into their concepts of self, based on the same principles by which ideas are spread throughout society. Just as suicide impacts on society, so does society impact on suicide.

Enzymatic removal of selected aromatic contaminants from wastewater by a fungal peroxidase from Coprinus macrorhizus in batch reactors.

Abstract: The use of enzymes such as horseradish peroxidase (HRP) for degrading or removing toxic organics from synthetic wastewater has been demonstrated previously. Potential alternatives to HRP are other peroxidases, various ligninases, haloperoxidases and laccases. Results of this study indicate that a fungal peroxidase from Coprinus macrorhizus (CMP) has the capability to catalyze the same reactions as HRP. Similarly, in batch reactors the trend and removal efficiency of aromatic compounds by CMP from synthetic wastewater depend on the nature of the compound.

Examination of the relationship between the myers-briggs type indicator and the neo personality inventory '

Abstract: The study examined the relationship between scores on the Myers-Briggs Type Indicator and on the NEO Personality Inventory by administering these measures to 161 women and 48 men in introductory ps...

Frequency ratios and the discrimination of pure tone sequences

Abstract: We examined the effect of frequency ratios on the discrimination of patterns of alternating pure tones (ABABA). Listeners heard a repeating pattern presented in transposition (same frequency ratios between successive tones, different absolute frequencies) and were required to indicate when the pattern changed (different frequency ratios and absolute frequencies). Changes from patterns with simple frequency ratios to those with more complex ratios were more readily detected than were changes from complex ratios to simpler ratios.

Kinetics of denitrification by Pseudomonas fluorescens: Oxygen effects

Abstract: To determine the inhibitory effect of O2 on denitrification in pure cultures of Pseudomonas fluorescens, measurements of net NO and N2O production rates, fNO and fN2O, under anaerobic conditions were compared to rates under partially aerobic conditions. Nitrate or NO2− solutions were injected into buffered suspensions and gaseous NO and N2O were sparged by constant flows of N2 carrier gas, or mixtures of N2 with measured small quantities of O2 (ca 6–60 Pa). Apparent Michaelis-Menten parameters were calculated from saturation kinetic plots obtained by monitoring net NO or N2O production following periodic addition of NO3−, NO2− or NO to suspensions of cells cultured aerobically in the absence of NO3−. With NO3− substrate added under anaerobic conditions the apparent KM=3,74± l.80mM, and under partially aerobic conditions KM =2.10 ± 0.54 mM; with NO2− substrate (anaerobic conditions) KM = 5.28±0.76 nM (partially aerobic conditions), KM=6.05± 1.30 μM, and with NO substrate, anaerobic conditions, KM = 7.3 ± 7.4 mu. The addition of O2 resulted in short-term transient effects indicating rapid and reversible inhibition of NO and N2O production. When O2 was present, NO2−, accumulated in greater amounts than observed under completely anaerobic conditions. The transient effects suggest that the reduction of NO2−, NO and N2O are each inhibited to increasingly greater extents by O2.

Structure and growth of platelets in graphite spherulites in cast iron

Abstract: The structure and orientation of graphite platelets in graphite spherulites (GS) in cast irons modified by either cerium or magnesium plus cerium were investigated by TEM and micro-diffraction. The platelets have a rhombohedral structure with their [001] directions nearly parallel to the radius of the GS, but each platelet is twisted about 2 ° over a 1 μm length. Randomly orientated graphite is located in the interplatelet areas, in which most of the graphite has a hexagonal structure rather than rhombohedral structure. Based on the crystallographic characterization of the graphite and the cerium and magnesium elemental distribution in the GS, the model for the growth of GS as originally proposed by Double and Hellawell is re-examined.