Showing papers by "Ryerson University published in 2002"
TL;DR: The study indicated that the smaller the size of the MSW the faster the biodegradation rate of the waste, which eventually cause a reduction of the contaminant life span of the landfill and decrease in the cost of long term monitoring.
195 citations
TL;DR: In this paper, a new method for predicting the surface roughness of the workpiece for the grinding process is developed, which takes into consideration the random distribution of the grain protrusion heights.
Abstract: A new method for predicting the surface roughness of the workpiece for the grinding process is developed in this paper. The conventional method determines the surface roughness based on the model using the mean value of the grain protrusion heights, which leads to a formula. However, the analytical value based on the formula is substantially smaller than measurement. To overcome this problem, the proposed method takes into consideration the random distribution of the grain protrusion heights. As such, there is no formula, and a numerical solution is developed. To solve this problem, first the intersecting points of any two grains with different heights are determined. To determine the final profile considering thousands of the grains, a search method is developed to systematically solve the workpiece profile, starting with the highest protruded grain in a descending order of the grain protrusion heights. Furthermore, a truncated Gaussian distribution model is developed to relate the wheel volume wear to the change in the mean value of the protrusion heights. Simulation shows that the proposed method yields the results that are consistent with measurement, thereby proving the effectiveness of the method.
191 citations
TL;DR: The results provide a framework for using spectral parameter methods to monitor apoptosis in in vitro and in in vivo systems and are being used to guide the design of system and signal analysis parameters.
Abstract: Ultrasound (US) spectral analysis methods are used to analyze the radiofrequency (RF) data collected from cell pellets exposed to chemotherapeutics that induce apoptosis and other chemicals that induce nuclear transformations. Calibrated backscatter spectra from regions-of-interest (ROI) were analyzed using linear regression techniques to calculate the spectral slope and midband fit. Two f/2 transducers, with operating frequencies of 30 and 34 MHz (relative bandwidths of 93% and 78%, respectively) were used with a custom-made imaging system that enabled the collection of the raw RF data. For apoptotic cells, the spectral slope increased from 0.37 dB/MHz before drug exposure to 0.57 dB/MHz 24 h after, corresponding to a change in effective scatterer radius from 8.7 to 3.2 m. The midband fit increased in a time-dependent fashion, peaking at 13dB 24 h after exposure. The statistical deviation of the spectral parameters was in close agreement with theoretical predictions. The results provide a framework for using spectral parameter methods to monitor apoptosis in in vitro and in in vivo systems and are being used to guide the design of system and signal analysis parameters. (E-mail: mkolios@ryerson.ca) © 2002 World Federation for Ultrasound in Medicine & Biology.
179 citations
TL;DR: Interparticle interactions affecting the stability of sludge flocs taken from laboratory-scale sequencing batch reactors at different solids retention times (SRTs) were investigated in batch experiments by varying the pH, ionic strength, cation valence, and urea and ethylenediaminetetraacetate concentrations of suspending solutions.
164 citations
TL;DR: In this article, the influence of organizational factors such as size and type (feminist or not) were found to be related to the extent of formal collaborative activity, but the strength of these factors as predictors of behavior was amplified or reduced by the intervening perception of the impact of environmental changes.
Abstract: Using a sample of 645 nonprofit organizations in Canada, the authors construct and validate a regression model to explain predisposition to collaborate. Organizational factors such as size and type (feminist or not) were found to be related to the extent of formal collaborative activity. However, the strength of these factors as predictors of behavior was amplified or reduced by the intervening perception of the impact of environmental changes. In addition, the perception of these pressures was shown to intensify the motivation to collaborate, which in turn increases the probability of engaging in formal interorganizational activity. This study contributes to the body of knowledge about collaboration because previous research has not investigated the influence of a combination of factors on collaborative behavior.
148 citations
TL;DR: A research effort was undertaken that demonstrates the complexity of calibrating accident prediction models for urban intersections and the results are mixed, suggesting that a single calibration factor as is currently specified in the IHSDM procedure may be inappropriate and that a disaggregation by traffic volume might be preferable.
Abstract: Accident prediction models, also known as safety performance functions, have several important uses in modern-day safety analysis. Unfortunately, calibration of these models is not straightforward. A research effort was undertaken that demonstrates the complexity of calibrating these models for urban intersections. These complexities relate to the specification of the functional form, the accommodation of the peculiarities of accident data, and the transferability of models to other jurisdictions. Toronto data were used to estimate models for three- and four-legged signalized and unsignalized intersections. Then the performance of these models was compared with that of models for Vancouver and California that were recalibrated for Toronto using a procedure recently proposed for the application in the Interactive Highway Safety Design Model (IHSDM). The results of this transferability test are mixed, suggesting that a single calibration factor as is currently specified in the IHSDM procedure may be inappropriate and that a disaggregation by traffic volume might be preferable.
137 citations
TL;DR: In this paper, the characteristics and mechanisms of enhanced electrochemical properties for a Mg 2 Ni alloy produced by a ball-milling treatment were investigated by electrochemical measurements and XRD analysis.
116 citations
TL;DR: A new approach to medical image analysis that combines deformable model methodologies with concepts from the field of artificial life is introduced, including a "corpus callosum worm" that can overcome noise, incomplete edges, considerable anatomical variation, and interference from collateral structures to segment and label the corpusCallosum in 2D mid-sagittal MR brain images.
106 citations
TL;DR: For instance, the authors examined adolescents' and mothers' understanding of children's self-determination and nurturance rights in the context of the home and found that mothers' reasoning about children's rights reflected sensitivity to the developmental level of their children.
Abstract: Adolescents' and mothers' understanding of children's self-determination and nurturance rights was examined in the context of the home. In individual interviews, 141 sixth, eighth, and tenth graders and their mothers responded to hypothetical vignettes in which a child story character wished to exercise a right that conflicted with parental practices. For each vignette, participants were asked to judge whether the story character should have the right in question and to provide a justification for their decision. Generally, eighth and tenth graders were more likely than their mothers to endorse requests for self-determination and less likely than their mothers to support requests for nurturance. Mothers of tenth graders were more likely to support requests for self-determination and less likely to favor adolescents' request for nurturance in the home than were mothers of sixth and eighth graders. In terms of reasoning, adolescents and mothers were more likely to consider the individuals' rights when discussing self-determination situations, whereas nurturance situations elicited responses pertaining to participants' understanding of familial roles and relationships. Furthermore, mothers' reasoning about childrenAs rights reflected sensitivity to the developmental level of their children. The findings are discussed in terms of previous research on the development of children's understanding of rights and adolescent autonomy.
105 citations
98 citations
TL;DR: It is suggested that the current array of theories be updated and comprehensive research programs be encouraged to assess their clinical utility with various populations in a variety of settings.
Abstract: Restraining and secluding children living in residential facilities, though controversial, are commonly practiced by staff to manage disruptive behavior. In an effort to address some of the ongoing issues about the practice, this article examined the reasons for their use, their theoretical underpinnings, and extant empirical evidence in support of the theories. It is suggested that the current array of theories be updated and comprehensive research programs be encouraged to assess their clinical utility with various populations in a variety of settings.
TL;DR: Measurements and simulation results show that gradually saturating amplitude nonlinearity can be adequately linearized with some backoff from the clipping limit.
Abstract: The biggest concern in the use of radio-over-fiber (ROF) links in wireless access is their limited dynamic range due to nonlinear distortion (NLD). In this paper, a higher order adaptive filter based nonlinearity compensation scheme is proposed. Pre-compensation is done for the downlink while post-compensation is done for the uplink to result in asymmetry with respect to complexity. This centralized signal processing is attractive in that it keeps the remote unit simple. Accurate measurements of ROF link parameters are not required with this approach because the filters are adapted from the distortion of the input/output base band signal. This technique also facilitates fast tracking of modifications and drifts in the link characteristics. Measurements and simulation results show that gradually saturating amplitude nonlinearity can be adequately linearized with some backoff from the clipping limit. A 42% backoff is required for pre-compensation to protect the laser while only a 16.7% backoff is required for post-compensation. Phase pre-compensation is accomplished with a higher accuracy than phase post-compensation.
TL;DR: In this article, a simple method to determine the coefficient of thermal expansion at early ages is proposed, which consists in submitting concrete samples instrumented with vibrating wire extensometers to thermal shocks.
Abstract: Autogenous shrinkage, which is a consequence of the absolute volume contraction resulting from cement hydration, occurs in any concrete but its effect is particularly amplified in high performance concrete in which it can be as large as drying shrinkage. Autogenous shrinkage can be directly measured in concrete samples under isothermal conditions but from a practical standpoint the experimental procedure is not always possible. On the other hand, it can be evaluated after having taken into account volumetric variations due to the release in heat during cement hydration. To separate the thermal effect from autogenous shrinkage, it is necessary to know at any moment the evolution of the coefficient of thermal expansion of the concrete from initial setting. A simple method to determine the coefficient of thermal expansion at early ages is proposed in this paper. It consists in submitting concrete samples instrumented with vibrating wire extensometers to thermal shocks. The response of the concrete sample to this shock results in a nearly instantaneous deformation, which is measured by the sensor. These deformations, as well as the temperature signal, are used to calculate the coefficient of thermal expansion. By repeating this experiment at various ages, it is possible to follow the variation in the coefficient of thermal expansion of the concrete over time.
TL;DR: The importance of tourism to the Caribbean, key tourist destinations, challenges, sustainable development, and community involvement are discussed in this paper, where the author recommends product diversification and well-planned community participation in tourism development for the Caribbean.
Abstract: This paper attempts to capture the essence of the key elements needed to master tourism in the Caribbean. The author uses his eight years (1994‐2001) hospitality and tourism management and research experience in the Caribbean in writing this paper. He also uses information gathered by participating in ten major hospitality and tourism regional conferences and some 175 elite interviews he conducted with stakeholders of Caribbean tourism during the last three years. The paper analyses the importance of tourism to the Caribbean, key tourist destinations, challenges, sustainable development and community involvement. In conclusion, the author recommends product diversification and well‐planned community participation in tourism development for the Caribbean. The paper also calls for well‐coordinated efforts by all stakeholders to ensure sustainability of tourism development in the Caribbean.
08 May 2002
TL;DR: A simple and efficient method is proposed to estimate velocity from an incremental encoder pulse train based on the physical characteristics of incremental encoders, which allows the user to select the estimation precision and tune the time delay, and yet requires less calculation than other methods.
Abstract: Velocity measurement is often required in control system design of mechanical machines including robot manipulators. However, precise velocity measurement/estimation remains a challenging task, especially for very slow motions. Several methods have been published to estimate velocity from position measurements, typically the output of an incremental optical encoder. In the present work, a simple and efficient method is proposed to estimate velocity from an incremental encoder pulse train. Based on the physical characteristics of incremental encoders, the proposed method allows the user to select the estimation precision and tune the time delay, and yet requires less calculation than other methods. The proposed method is evaluated experimentally using a direct drive robot arm. An external laser dynamic calibrator is used to obtain accurate reference velocity measurements for comparison. Experimental results confirm the advantages of the proposed method.
TL;DR: In this paper, the optimal operating conditions of chemical nitrate reduction with fine aluminum powder are evaluated through controlled laboratory testing using the standard jar-test apparatus, and a maximum of 62% nitrate removal was achieved with the following conditions: 300 mg/l aluminum dose, water temperature of 25°C, pH of 10.7, and initial nitrate concentration of 20mg/l as N.
TL;DR: Data from the city of Hamilton, Ontario, were used to test the transferability of the Toronto four-legged signalized intersection model, and the test was successful: the recalibrated Toronto models predicted collision numbers that were very close to those predicted by the model calibrated directly for the Hamilton data.
Abstract: In more recent safety analysis methods, collision prediction models can be used for identifying intersections with promise of safety improvement and for evaluating the effects of treatment. Considerable effort has been directed at developing collision prediction models, but little has been directed at pedestrian collisions. Collisions involving motor vehicles and pedestrians pose a significant safety problem, principally in urban areas, where the levels of vehicle-pedestrian conflicts are high. Data from Toronto, Canada, are used in the development of pedestrian collision prediction models for three- and four-legged urban intersections, with and without signal control. These models, which relate safety to pedestrian and vehicle traffic volumes, can be used to identify locations that might be targeted for treatment and to help evaluate treatment effects. Models are developed by using pedestrian and vehicular volumes and vehicle volumes only. It is seen that the use of pedestrian volume information results in a much richer model, emphasizing the importance of collecting this information in routine traffic counting programs. An important issue for collision prediction models is transferability to other jurisdictions. This is especially important in the case of pedestrian collision models, because many jurisdictions may not have data sets containing sufficient collisions and pedestrian volume counts with which to calibrate reliable models. Data from the city of Hamilton, Ontario, were used to test the transferability of the Toronto four-legged signalized intersection model. The test was successful: the recalibrated Toronto models predicted collision numbers that were very close to those predicted by the model calibrated directly for the Hamilton data.
TL;DR: The simplified model strongly suggests that much of observed large increases of the backscattered signals could be simply explained by the randomisation of the position of the condensed nuclei during apoptosis, and the destruction of the nuclei could produce further signal amplitude changes due to disruption of the cloud of backscattering waves.
Abstract: Recent ultrasound (US) experiments on packed myeloid leukaemia cells have shown that, at frequencies from 32 to 40 MHz, significant increases of signal amplitude were observed during apoptosis. This paper is an attempt to explain these signal increases based upon a simulation of the backscattered signals from the cells nuclei. The simulation is an expansion of work in which a condensed sample of cells, with fairly regular sizes, could be considered as an imperfect crystal. Thus, destructive interference could occur and this would be observed as a large reduced value of backscattered signals compared with the values obtained from a similar, but random, scattering source. This current paper explores the possibility that simple changes in the nuclei, such as their observed condensation or the small loss of nuclei scatterers from cells, could cause a significant increase in the observed backscattered signals. This model indicates that the greater backscattered signals can be explained by further randomisation of the average positions of the scattering sources in each cell. When these “microechoes” are added together, so that the destructive interference is reduced, a large increase in the signal is predicted. The simplified model strongly suggests that much of observed large increases of the backscattered signals could be simply explained by the randomisation of the position of the condensed nuclei during apoptosis, and the destruction of the nuclei could produce further signal amplitude changes due to disruption of the cloud of backscattered waves. (E-mail: hunt@uhnres.utoronto.ca)
TL;DR: In this paper, the surface microstructure and polymorphic behavior of milk chocolate subjected to multiple thermal cycles between 20 and 32, 33, or 34°C were examined using atomic force microscopy (AFM) and powder X-ray diffraction (XRD).
Abstract: The surface microstructure and polymorphic behavior of milk chocolate subjected to multiple thermal cycles between 20 and 32, 33, or 34°C were examined using atomic force microscopy (AFM) and powder X-ray diffraction (XRD). The surface of unbloomed milk chocolate was smooth (surface roughness of 278 nm) and consisted of small, evenly distributed crystals. XRD results indicated the presence of mostly form V crystals and little or no form VI crystals. Cycling between 20 and 32°C resulted in little bloom formation and change in polymorphic behavior. Gradual bloom formation occurred as a result of cycling between 20 and 33°C, and was accompanied by the nascence of form VI crystals. Surface roughness increased gradually from 417 nm after one cycle to 476 and 521 nm after two and three cycles, respectively. Extensive bloom arose from cycling between 20 and 34°C. Surface roughness increased from 373 nm after one cycle to 603 and 736 nm after two and three cycles, respectively. This heavily bloomed chocolate consisted of jutting crystals and large raised, yet smooth areas that were haphazardly located within the chocolate matrix. In summary, a new perspective on the development of surface bloom due to thermal cycling is provided.
07 Aug 2002
TL;DR: It is shown that both image-based and position-based visual servoing methods are locally asymptotically stable and robust with respect to camera and target modeling errors, however the stability boundary withrespect to above errors has not been established.
Abstract: This paper presents a theoretical comparison of the stability and robustness of the two basic visual servoing methods, image-based and position-based visual servoing. A common framework for comparison based on the energy shaping plus damping injection methodology is presented. Previous stability results for the image-based method are extended to show the robustness of stability with respect to camera and target modeling, errors. Similar stability and robustness analyses are extended to the analysis of the position-based method. It is shown that both methods are locally asymptotically stable and robust with respect to camera and target modeling errors. However the stability boundary with respect to above errors has not been established.
TL;DR: In this article, the use of the principles of thermodynamics via exergy to evaluate energy systems and technologies as well as environmental impact is described and its use as a tool to improve efficiency illustrated.
TL;DR: Experimental results show robust and accurate performance by the proposed method, as compared with conventional noninteractive content-based image retrieval systems and user controlled interactive systems, when applied to image retrieval in compressed and uncompressed image databases.
Abstract: In this paper, an unsupervised learning network is explored to incorporate a self-learning capability into image retrieval systems. Our proposal is a new attempt to automate recursive content-based image retrieval. The adoption of a self-organizing tree map (SOTM) is introduced, to minimize the user participation in an effort to automate interactive retrieval. The automatic learning mode has been applied to optimize the relevance feedback (RF) method and the single radial basis function-based RF method. In addition, a semiautomatic version is proposed to support retrieval with different user subjectivities. Image similarity is evaluated by a nonlinear model, which performs discrimination based on local analysis. Experimental results show robust and accurate performance by the proposed method, as compared with conventional noninteractive content-based image retrieval (CBIR) systems and user controlled interactive systems, when applied to image retrieval in compressed and uncompressed image databases.
TL;DR: The equity/asset ratio is shown to provide as good a prediction of failure as any of the other models, and is not improved upon by the much more complex Z -score model.
TL;DR: In this article, a linear parametric friction model is formulated by linearizing a nonlinear empirical friction model in parameters, and a decomposition-based control design framework is applied to synthesize the friction compensation scheme.
01 Dec 2002
TL;DR: There is evidence to suggest that discourse related to information technology has the effect of excluding women and multi-disciplinary perspectives, and the exclusion of multiple disciplines and women may contribute to poor technology decision-making at the societal and organizational level.
Abstract: This paper examines implications of definitions of information technology to women's participation in the industry and in academe. It is exploratory only, based on a review of selected government and industry reports and data related to IT education and the profession. However, it argues that there is evidence to suggest that discourse related to information technology has the effect of excluding women and multi-disciplinary perspectives. On the one hand, there is considerable evidence that the IT industry and skills it demands are multi-disciplinary and that many people working in the industry, particularly women, come from a variety of disciplines. On the other hand, despite the evidence of the multidimensional nature of IT, the impact of convergence, the importance of matching IT solutions to user needs and so on, a very narrow definition of IT dominates the discourse. This definition equates IT and IT professionals with computer science and engineering, disciplines which are predominately male. The result, then of this narrow definition is to marginalize women and their contributions. This is a pattern that has been observed with the development of other disciplines such as medicine. Not only does the narrowing of the definition of Information Technology tend to exclude and devalue the contribution of women but it also results in marginalization of other disciplines that would bring more "neutral" or "critical" perspectives to bear on technology. Thus the exclusion of multiple disciplines and women may contribute to poor technology decision-making at the societal and organizational level.
TL;DR: In this article, the authors used a dynamic model which couples the hydraulics of a piping system with the structural motion of an air-operated, plug-type automatic control valve.
01 Jun 2002-Journal of International Migration and Integration \/ Revue De L'integration Et De La Migration Internationale
TL;DR: This article examined both the statistical and substantive dimensions of ethnoracial electoral representation in Toronto and concluded that minority communities are numerically badly underrepresented in Toronto across all levels of government and the record of minority-identity politicians on municipal council suggests they do not necessarily serve minority community interests well.
Abstract: This paper examines both the statistical and substantive dimensions of ethnoracial electoral representation in Toronto. We compare politician profiles across the municipal, provincial and federal arenas of politics and conclude there is a dual “representation gap’ in Toronto’s electoral politics. First, minority communities—especially visible minorities—are numerically badly underrepresented in Toronto across all levels of government. Second, the record of minority-identity politicians on municipal council suggests they do not necessarily serve minority community interests well. The paper analyzes these patterns and problems, concluding that solutions likely lie beyond the parameters of liberal democratic norms of political representation.
TL;DR: Initial field trials conducted using water sampled from Lake Erie demonstrate that the bioreporter can serve as a quantitative tool to assess Fe deficiency in natural freshwater environments.
Abstract: A Synechococcus sp. PCC 7942 bioreporter strain capable of sensing bioavailable Fe was constructed by fusing the Fe-responsive isiAB promoter to the Vibrio harveyi luxAB genes. Monitoring luxAB-dependent luminescence through the growth curve demonstrated that in Fe-replete media, transcription from the isiAB promoter was induced transiently in the mid-exponential phase of growth. The initiation of transcription was the functional response to a 10-fold depletion of intracellular Fe to ∼12 amol Fe per cell. Constitutive isiAB-dependent transcription was observed in Fe-depleted growth media. A dose–response relationship of the bioreporter was generated using trace metal-buffered Fraquil medium and was best represented by a sigmoidal curve having a linear component extending between pFe 21.1 (Fe3+=10−21.1 M) and pFe 20.6 (Fe3+=10−20.6 M). Initial field trials conducted using water sampled from Lake Erie demonstrate that the bioreporter can serve as a quantitative tool to assess Fe deficiency in natural freshwater environments.
TL;DR: In this article, material emissions produced during thirteen fuel life cycles for automobiles, on mass and exergy bases, are compared with the chemical exergies of these emissions, suggesting that compressed natural gas use in motor vehicles produces emissions that are the most out of equilibrium with the natural environment relative to all other fuel life cycle paths considered.
TL;DR: In this article, a survey of references pertaining to straight and curved box girder bridges in the form of single-cell, multiple-spine, and multicell cross sections is presented.
Abstract: The curvilinear nature of box girder bridges along with their complex deformation patterns and stress fields have led designers to adopt approximate and conservative methods for their analyses and design. Recent literature on straight and curved box girder bridges has dealt with analytical formulations to better understand the behavior of these complex structural systems. Few authors have undertaken experimental studies to investigate the accuracy of existing methods. This paper presents highlights of references pertaining to straight and curved box girder bridges in the form of single-cell, multiple-spine, and multicell cross sections. The literature survey presented herein deals with: (1) elastic analysis, and (2) experimental studies on the elastic response of box girder bridges.