Showing papers by "Concordia University published in 1992"
01 May 1992
TL;DR: On applying these methods to combine several classifiers for recognizing totally unconstrained handwritten numerals, the experimental results show that the performance of individual classifiers can be improved significantly.
Abstract: Possible solutions to the problem of combining classifiers can be divided into three categories according to the levels of information available from the various classifiers. Four approaches based on different methodologies are proposed for solving this problem. One is suitable for combining individual classifiers such as Bayesian, k-nearest-neighbor, and various distance classifiers. The other three could be used for combining any kind of individual classifiers. On applying these methods to combine several classifiers for recognizing totally unconstrained handwritten numerals, the experimental results show that the performance of individual classifiers can be improved significantly. For example, on the US zipcode database, 98.9% recognition with 0.90% substitution and 0.2% rejection can be obtained, as well as high reliability with 95% recognition, 0% substitution, and 5% rejection. >
2,389 citations
TL;DR: A comprehensive survey of thinning methodologies, including iterative deletion of pixels and nonpixel-based methods, is presented and the relationships among them are explored.
Abstract: A comprehensive survey of thinning methodologies is presented. A wide range of thinning algorithms, including iterative deletion of pixels and nonpixel-based methods, is covered. Skeletonization algorithms based on medial axis and other distance transforms are not considered. An overview of the iterative thinning process and the pixel-deletion criteria needed to preserve the connectivity of the image pattern is given first. Thinning algorithms are then considered in terms of these criteria and their modes of operation. Nonpixel-based methods that usually produce a center line of the pattern directly in one pass without examining all the individual pixels are discussed. The algorithms are considered in great detail and scope, and the relationships among them are explored. >
1,827 citations
01 Jul 1992
TL;DR: Both template matching and structure analysis approaches to R&D are considered and it is noted that the two approaches are coming closer and tending to merge.
Abstract: Research and development of OCR systems are considered from a historical point of view. The historical development of commercial systems is included. Both template matching and structure analysis approaches to R&D are considered. It is noted that the two approaches are coming closer and tending to merge. Commercial products are divided into three generations, for each of which some representative OCR systems are chosen and described in some detail. Some comments are made on recent techniques applied to OCR, such as expert systems and neural networks, and some open problems are indicated. The authors' views and hopes regarding future trends are presented. >
892 citations
Book•
01 Jan 1992TL;DR: This book discusses Graphs and Vector Spaces, which are concerned with the construction of graphs, and some of the algorithms used to solve these problems.
Abstract: Basic Concepts. Trees, Cutsets, and Circuits. Eulerian and Hamiltonian Graphs. Graphs and Vector Spaces. Directed Graphs. Matrices of a Graph. Planarity and Duality. Connectivity and Matching. Covering and Coloring. Matroids. Graph Algorithms. Flows in Networks. Indexes.
500 citations
01 Jul 1992
TL;DR: It is shown that it is possible to reduce the substitution rate to a desired level while maintaining a fairly high recognition rate in the classification of totally unconstrained handwritten ZIP code numerals.
Abstract: Four independently, developed expert algorithms for recognizing unconstrained handwritten numerals are presented. All have high recognition rates. Different experimental approaches for incorporating these recognition methods into a more powerful system are also presented. The resulting multiple-expert system proves that the consensus of these methods tends to compensate for individual weaknesses, while preserving individual strengths. It is shown that it is possible to reduce the substitution rate to a desired level while maintaining a fairly high recognition rate in the classification of totally unconstrained handwritten ZIP code numerals. If reliability is of the utmost importance, substitutions can be avoided completely (reliability=100%) while retaining a recognition rate above 90%. Results are compared with those for some of the most effective numeral recognition systems found in the literature. >
422 citations
TL;DR: This analysis has emerged from the joint consideration of how both appetitive and defensive behaviours are influenced by dopamine antagonists, along with an examination of dopamine release during sequences of behaviour, suggesting that dopamine is involved in fundamental psychological processes through which environmental stimuli come to exert control over certain aspects of behaviour.
405 citations
TL;DR: In this paper, it was shown that sea-salt Br− reaches high concentrations in the snow pack during the long polar night, and is evolved into the atmosphere as Br2 at polar sunrise.
Abstract: RECENT measurements1–7 in the Arctic have revealed episodic destruction of boundary-layer ozone from 30–40 parts per 109 by volume (p.p.b.v.) to undetectable levels on a timescale of less than a day, during periods when the boundary layer is very stable. The ozone destruction begins at polar sunrise, continues for the months of March and April, and is strongly associated with levels of filterable bromine which are much greater than during the rest of the year. Here we suggest that sea-salt Br− reaches high concentrations in the snow pack during the long polar night, and is evolved into the atmosphere as Br2at polar sunrise. Ordinarily, gas-phase photochemistry would convert Br2 to HBr or brominated organic compounds with consequently little destruction of boundary-layer ozone. In view of several laboratory experiments8–11, and by analogy with the marine boundary layer12, we propose that the HBr and brominated organic compounds will be scavenged by the ambient aerosols and ice crystals, and that these heterogeneous reactions release Br2 back to the atmosphere. We argue that this cycling of bromine between the aerosol and the gas phase should maintain sufficiently high levels of Br atoms and BrO radicals to destroy ozone, in agreement with observations1–7.
323 citations
TL;DR: Five brain sites have been advanced as sites of rewarding opiate actions: the ventral tegmental area, nucleus accumbens septi, lateral hypothalamus, periaqueductal gray, and hippocampus; each of the clearly implicated sites is local to dopamine cell bodies or dopamine terminals that have been implicated in the rewarding effects of brain stimulation, food, and sex.
Abstract: Intracranial drug injections are useful in localizing brain areas where drugs of abuse initiate their habit-forming actions. However, serious methodological problems accompany such studies. Pharmacological controls are necessary to assess non-receptor-mediated local actions of the drug, anatomical controls are necessary to rule out drug efflux to distal sites of action, and behavioral controls are necessary to separate rewarding from general activating effects of drugs. Five brain sites have been advanced as sites of rewarding opiate actions: the ventral tegmental area (VTA), nucleus accumbens septi (NAS), lateral hypothalamus, periaqueductal gray, and hippocampus. Current evidence appears to confirm two of these--VTA and NAS; evidence is currently incomplete in the case of the hippocampus and is conflicting in the case of the lateral hypothalamus and periaqueductal gray. Two sites have been advanced as sites of rewarding psychomotor stimulant actions: NAS and the frontal cortex; each site seems implicated, but puzzling differences between amphetamine and cocaine findings remain to be resolved. Each of the clearly implicated sites is local to dopamine cell bodies or dopamine terminals that have been implicated in the rewarding effects of brain stimulation, food, and sex.
276 citations
256 citations
TL;DR: In this article, the influence of buoyancy force on heat or mass transfer rate was investigated in a stable state thermosolutal convection in a square cavity filled with air, submitted to horizontal temperature and concentration gradient.
229 citations
TL;DR: Adult facial expressions are not the only modulator of infant affect and attention during social exchanges; adult touch appears to play an active role.
Abstract: 3 studies were designed to investigate infant responses to tactile stimulation during brief adult-infant interaction using a modified still-face (SF) procedure. When adults pose a neutral SF expression, infants decrease gazing and smiling at the adults, and some increase grimacing, relative to normal interaction periods. This SF effect was substantially reduced in Study 1 when mothers or strangers continued to touch infants during the SF period. In Studies 2 and 3, tactile versus visual and active versus passive aspects of adult touch were isolated during different SF periods. Visible, active adult hands unaccompanied by touch elicited infant attention, but not smiling, during the SF period. By contrast, active, not passive, adult touch substantially reduced the SF effect, even when the adult's hands were invisible. In the latter condition, infants continued to gaze and smile at the adult's SF. Thus, adult facial expressions are not the only modulator of infant affect and attention during social exchanges; adult touch appears to play an active role.
TL;DR: A test of the complete Job Characteristics Model (Hackman & Oldham, 1976, 1980) was conducted, with particular emphasis on the little-investigated mediating and moderating effects specified by the model as mentioned in this paper.
TL;DR: The hypothesis that shoes with thick, soft midsoles, such as modern running shoes, provide better stability in older individuals than those with thin‐hard midsoles is tested.
Abstract: OBJECTIVE: To test the hypothesis that shoes with thick, soft midsoles, such as modern running shoes, provide better stability in older individuals than those with thin-hard midsoles. In addition, we examined the relation between footwear comfort and stability and stability when barefoot. DESIGN: Randomized-order, cross-over, controlled comparison. SETTING: Subjects were drawn from an internal medicine practice. PARTICIPANTS: A random sample of 25 healthy men, minimum age 60 years. Additional selection criteria were absence of disabilities influencing ability to walk and lack of history of frequent falls. MEASUREMENTS: Balance failure frequency, which was defined as falls from the beam per 100 meters of beam walking when 10 passes were made down a 9 M long balance beam. Comfort rating was based on an ordinal scale. RESULTS: Contrary to the hypothesis: (1) midsole softness was associated with poor stability (F(2,48) = 17.9, P Language: en
TL;DR: In this paper, the authors examined the mechanisms of absorption and established a means of developing and using absorption constants for PCM concrete to achieve diffusion of the desired amount of organic PCM and hence the required thermal storage capacity.
TL;DR: In this article, the authors examined the relationship of shiftwork and department-type with employees' job stress, stressors, work attitudes and behavioral intention and concluded that nurses working on fixed shifts were better off than nurses working rotating shifts in terms of the dependent variables of the present study.
Abstract: Summary The present study examined the relationship of shiftwork and department-type with employees' job stress, stressors, work attitudes and behavioral intention. Data were collected by means of a structured questionnaire from nurses (N= 1148) working in eight hospitals in a large, metropolitan city in eastern Canada. One-way ANOVA, MANOVA and two-way ANOVA were used to analyze data. Results generally support the prediction that nurses working on fixed shifts were better off than nurses working on rotating shifts in terms of the dependent variables of the present study. The prediction that nurses working in non-intensive care departments were better off than nurses working in intensive care departments received mixed support at best. A few interaction effects of shiftwork x department-type on dependent variables were also noted. The impact of socio-demographic variables - age, marital status, cultural background (English- versus French-speaking) on the above relationships were also analyzed. Results are discussed in light of the previous empirical evidence on shiftwork and department-type.
TL;DR: Oscillations in the Hall resistance, the cyclotron resonance position, the linewidth, as well as in the thermal conductivity and thermopower are predicted.
Abstract: We investigate the influence of a periodic weak modulation along the x direction on the electrical and thermal properties of a two-dimensional electron gas in the presence of a perpendicular magnetic field. The modulation lifts the degeneracy of the Landau levels and leads to one-dimensional magnetic bands whose bandwidth oscillates as a function of the magnetic field. At weak magnetic fields this gives rise to the Weiss oscillations in the magnetoresistance, discovered recently, which have a very weakly temperature-dependent amplitude and a period proportional to \ensuremath{\surd}${\mathit{n}}_{\mathit{e}}$ , when ${\mathit{n}}_{\mathit{e}}$ is the electron density. Diffusion-current contributions, proportional to the square of the bandwidth, dominate ${\mathrm{\ensuremath{\rho}}}_{\mathit{x}\mathit{x}}$, and collisional contributions, varying approximately as the square of the density of states, dominate ${\mathrm{\ensuremath{\rho}}}_{\mathit{y}\mathit{y}}$. The result is that ${\mathrm{\ensuremath{\rho}}}_{\mathit{x}\mathit{x}}$ and ${\mathrm{\ensuremath{\rho}}}_{\mathit{y}\mathit{y}}$ oscillate out of phase as observed. Asymptotic analytical expressions are presented for the conductivity tensor. Similar oscillations, of much smaller amplitude, occur in the thermodynamic quantities, such as the magnetization, the susceptibility, and the specific heat. We also predict oscillations in the Hall resistance, the cyclotron resonance position, the linewidth, as well as in the thermal conductivity and thermopower. The components of the thermal-resistance tensor have a magnetic-field dependence similar to that of the electrical-resistivity tensor.
TL;DR: The view that opioid-seeking behavior is primed by the proponent or opioid-like actions of opioids and not by the opponent or drug-opposite effects associated with opioid withdrawal is supported.
Abstract: The effects of morphine, naltrexone, and nalorphine were studied in rats trained to lever-press for intravenous heroin and then tested under conditions of non-reinforcement. Animals were reinforced for lever-pressing on a continuous reinforcement schedule (100 µg/kg per infusion) for 2–3 h each day following which reinforcement was terminated and animals were studied under extinction conditions for the remainder of the session. Each day following the termination of responding under extinction conditions, animals were given a single injection of saline, morphine, nalorphine, or naltrexone; lever-pressing under the extinction conditions was then observed for several hours. When animals adapted to this regimen, very low levels of responding were seen following saline injections; morphine (2 or 10 mg/kg) reinstated vigorous responding that lasted 1–4 h. Naltrexone (2 mg/kg) suppressed responding below the levels seen after saline, and nalorphine (10 mg/kg) had the same effect as saline. These observations support the view that opioid-seeking behavior is primed by the proponent or opioid-like actions of opioids and not by the opponent or drug-opposite effects associated with opioid withdrawal.
TL;DR: A shape matching technique based on the straight line Hough transform (SLHT) is presented, which allows the translation, rotation, and intrinsic parameters of the curve to be easily decoupled.
Abstract: A shape matching technique based on the straight line Hough transform (SLHT) is presented. In the theta - rho space, the transform can be expressed as the sum of the translation term and the intrinsic term. This formulation allows the translation, rotation, and intrinsic parameters of the curve to be easily decoupled. A shape signature, called the scalable translation invariant rotation-to-shifting (STIRS) signature, is obtained from the theta - rho space by computing the distances between pairs of points having the same theta value. This signature is invariant to translation and can be easily normalized, and rotation in the image space corresponds to circular shifting of the signature. Matching two signatures only amounts to computing a 1D correlation. The height and location of a peak (if it exists) indicate the similarity and orientation of the test object with respect to the reference object. The location of the test object is obtained, once the orientation is known, by an inverse transform (voting) from the theta - rho space to the x-y plane. >
TL;DR: Leucine is clearly a major effector of the regulon, in that it affects Lrp regulation in many, but not all, cases, and this sets the leucine-Lrp regulon apart-a global response in search of a physiological rationale.
TL;DR: In this paper, the high temperature flow curves for three stainless steels were calculated up to the peak stress σ p and peak strain ϵ p by using the sinh-Arrhenius constitutive equation.
29 Jun 1992
TL;DR: In this article, a three-phase PWM voltage source inverter, connected in series with the line through a threephase transformer, is proposed to balance the load voltage and to control the amplitude of the positive sequence component in order to perform load voltage regulation.
Abstract: Voltage unbalance in AC supply systems is typically corrected by means of a shunt connected thyristor-controlled static VAr compensator. This approach has the disadvantage of slow response, harmonic injection into the AC system, and the requirement for large passive components. The proposed system consists of a three-phase PWM voltage source inverter, connected in series with the line through a three-phase transformer. The unbalance compensation is achieved by canceling the negative sequence component of the line-to-line voltages of the source. It is also shown that by having the inverter operate with unbalanced switching functions, it is possible to balance the load voltage and to control the amplitude of the positive sequence component in order to perform load voltage regulation. A complete mathematical description of the method is presented, demonstrating that the compensation can be achieved with low kVA inverters and low harmonic injection. Implementation procedures, design equations, and a design example are also included in order to illustrate the proposed method. Experimental results of a 1.5 kVA laboratory prototype system confirm the feasibility of the technique. >
TL;DR: The ability of habit-forming drugs to potentiate the rewarding effects of medial forebrain bundle brain stimulation reward1547 offers a particularly useful model in which to quantify such interactions.
Abstract: Important advances in our understanding of the habit-forming effects of drugs have come from an appreciation of the ability of drugs to serve as operant reinforcers. An operant reinforcer is a stimulus event which, when made contingent upon some act of an animal, increases the probability of recurrence of that act. Intravenous injections of habit-forming drugs establish and maintain such arbitrary habits as lever-pressing, and drug self-administration by lever-pressing has provided us with animal models of intravenous drug-seeking in humans. Habit-forming drugs do more than merely serve as operant reinforcers, however. Animals learn to approach the portions of the environment where they have received drugs in the p a ~ t , l ~ and they do so through Pavlovian rather than operant conditioning.4 Habit-forming drugs also reinstate or \"prime\" operant responding after periods of non-reward or temporarily disrupted responding.5~6 Finally, they sometimes potentiate the effectiveness of other rewards: cannabis,7-9 amphetamine,lO.ll and opiatesl2*l3 facilitate feeding; opiates icilimte sexual behavior\" in animals; and cannabis is reported to enhance the rewarding effects of food, music, and sexual interaction in humans. The ability of habit-forming drugs to potentiate the rewarding effects of medial forebrain bundle brain stimulation reward1547 offers a particularly useful model in which to quantify such interactions. Most classes of abused drugs have been shown to increase lever-pressing for brain stimulation reward; this is true of amphetamine,l* cocaine,l9 nicotinq20.21 opiates,22 cannabis,23 phencyclidine,\" ethanol,25 barbiturates,% and benzodiazepine~.~~ In several cases it is clear that the drugs enhance the rewarding impact of the brain stimulation and do not merely enhance the response capacity of the animal. The primary evidence that a drug enhances the rewarding effects of brain stimulation is that the drug reduces the amount of stimulation needed to motivate normal responding.15 Rewarding stimulation is given in the form of brief trains of pulsed current, and the potency of each rewarding stimulation train is traditionally controlled
TL;DR: Analysis of populations within species or species within genera showed that undefended home ranges were larger than defended home ranges for carnivores and male ungulates, but not for primates.
Abstract: We tested the hypothesis that undefended home ranges are larger than defended home ranges using data collected from the literature for three groups of mammals. A matched-pairs analysis of populations within species or species within genera showed that undefended home ranges were larger than defended home ranges for carnivores and male ungulates, but not for primates. Primates may have been an exception because they violated a key assumption of the hypothesis, that defence costs increase with the size of the defended area. Undefended home ranges were 5.4 and 15.2 times larger than defended home ranges for carnivores and male ungulates, respectively. Whether or not a home range is defended is an important source of variation that should be included in future studies of home range size.
TL;DR: The results of this study indicate that the magnitude of stress-elicited increases in levels of extracellular dopamine is determined by the number of previous exposures to stress and are consistent with reports of sensitization to the behavioral effects of stress with repeated testing.
TL;DR: In this paper, a new type of replenishment policy is proposed for an inventory item having a finite shortage cost and linear trend in demand over a finite time horizon, which has a lower total cost as compared with the optimal solution for the traditional replenishment policies.
Abstract: A new type of replenishment policy is suggested for an inventory item having a finite shortage cost and linear trend in demand over a finite time horizon. The optimal solution of the suggested replenishment policy has a lower total cost as compared with the optimal solution for the traditional replenishment policies.
TL;DR: It is suggested that the lrp gene product activates genes needed for growth in minimal medium, and it is shown that the gene is repressed by its own product and is highly repressed during growth in rich medium.
Abstract: The leucine regulon coordinates the expression of several Escherichia coli genes according to the presence of exogenous leucine, which interacts with the lrp gene product, Lrp. We isolated and characterized 22 strains with lambda placMu insertions in Lrp-regulated genes. Lrp and leucine influenced gene expression in a surprising variety of ways. We identified two genes that are regulated by Lrp and not affected by L-leucine. We therefore rename this the leucine-lrp regulon. Genes coding for glycine cleavage and leucine biosynthesis enzymes have been identified as members of the leucine-lrp regulon. We suggest that the lrp gene product activates genes needed for growth in minimal medium, and we show that the gene is repressed by its own product and is highly repressed during growth in rich medium.
TL;DR: In this paper, phase change materials (PCMs) are used to increase the heat storage capacity of concrete building products by impregnating the concrete with phase change material (PCM) and the use of modified concrete is developed to increase this stability.
TL;DR: A role for brain catalase in determining the level of ethanol intake in rats is suggested as well as a dose-dependent inhibition of brainCatalase lasting throughout the drinking period.
TL;DR: The use of F.J. Olver's (1974) uniform asymptotic expansions to compute Hankel functions (of interest in EM scattering) of complex argument z and complex order v is examined in this paper.
Abstract: The use of F.W.J. Olver's (1974) uniform asymptotic expansions to compute Hankel functions (of interest in EM scattering) of complex argument z and complex order v is examined. Emphasis is placed on how to choose the proper branches in evaluation of the complex functions in the asymptotic representations. Comparison is made with the nonuniform formulas of Debye and Watson. The Debye formulas are valid when z and v are far apart, and the Watson formulas are valid when z and v are close together. The fact that the Olver formulas are uniform is important from a numerical viewpoint, because a satisfactory criterion for deciding when to switch between the Debye and Watson (1958) formulas is not available. Validation by comparison with two nonasymptotic methods verifies that the Olver formulas are considerably more accurate than the Debye or Watson formulas. >