150 research outputs found

    Simulation of hand cooling in contact with cold materials.

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    The contact between the hand and a cold surface causes a sudden cooling of the hand that leads to discomfort and in most extreme cases to pain or cold injury. The cooling of the hand in contact with a cold material surface is governed by several physiological parameters and environmental factors. Some of the parameters that affect the hand cooling process are the surface temperatures of materials and the skin, physical properties of the material and the skin tissues, the contact surface area, the contact pressure, body core temperature and the average skin temperature. The physical properties of the material and skin tissues can be viewed as the conductivities, specific heat capacities and the densities of each category. There are two distinct methods of determining the hand temperatures or the cooling rates of the hand due to touching cold surfaces. The most logical and easily adaptable method to analyse the hand cooling phenomenon is by using a thermoregulatory model that represents the human hand. The alternative approach will be to estimate the hand temperature using experimental methods. The aim of this thesis is to develop a numerical model that can be employed to simulate the hand cooling due to touching cold materials. For this purpose the empirical relationships developed by Lotens to represent the blood flow rates of the hand is considered as the foundation. The developed model shows good agreement with the experimental cooling curves. The long time and short time experimental hand cooling curves due to touching various materials at different temperatures are used to validate the model. The method of sensitivity analysis is used to investigate the impact of each input parameter on the output of the model.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .W35. Source: Masters Abstracts International, Volume: 45-01, page: 0460. Thesis (M.A.Sc.)--University of Windsor (Canada), 2005

    Surface plasmon microarray and voltage-driven biocatalysis for drug development and bioelectronics

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    The objectives of the research described in this dissertation are driven with a broader motivation to provide scientific solutions to real world problems related to human health and cleaner energy. Under global health issues, there are many challenges that need to be addressed, specifically in the laborious drug development process and characterization of small-molecule cancer drugs. The research strategies described in this work focus on developing analytical solutions for drug candidate identification, preclinical metabolite screening, and quality assurance of active pharmaceutical ingredients. A surface plasmon methodology was developed to study binding kinetics of oncogenic protein-protein interactions and their inhibition by small-molecule drugs. Additionally, a rapid one-step construction of the human liver membrane bioelectrodes for inexpensive, electrochemical drug metabolism and inhibition was formulated. Thirdly, the applicability of the screen printed electrodes was validated towards single drop electrocatalysis of pharmaceuticals as a cost-effective and instant analytical tool to determine the purity of an active chemical form of a drug. Under the focus of biocatalysis, high efficient nanostructure bioelectrode designs have been investigated for model catalytic reactions

    Exploring natural resources for sustainable management of ecosystems future challenges for control and management of Xyleborus fornicatus eichh. (Coleoptera Scolytidae), the shot-hole borer of tea in Sri Lanka

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    In view of the highly diverse genetic base of the seedling tea plants, though cultivated as a monocrop,along with shade trees and surrounding forests, provided a reasonably stable ecosystem then. Withthe introduction of high yielding vegetatively propagated tea during 1950's, a significant change in thedistribution and population densities of pests has been taken place. Shot-hole borer is one such pestand since then it has become the most serious and damaging pest of tea in Sri Lanka. Control hasbeen a difficult task as a result of its' wide distribution from near sea level up to 1500m amsl and theconcealed habit virtually protected from parasites and predators. Biological control usingentomopathogenic fungus, Beauvaria bassiana Vuillemin (Balsomo ) is being viewed as anenvironmentally friendly alternative to chemical control in the light of growing concern on the usage of pesticides and since oflate, the detection of pesticide residues in made tea. Preliminary investigationswere carried out with a view to find out a suitable local strain/s of the fungus for use against this pest.Laboratory studies have shown that strains of this fungus isolated from a tea garden in Talawakelle(Nuwera Eliya District) and a home garden in Welimada (Badulla District) are highly pathogenic toshot-hole borer imparting more than 90% mortality. A potential exists for using the locally availablenatural resources like entomopathogenic fungi for the management of key pests in a compatible andecologically acceptable manner. This forms the basis for Integrated Pest Management (lPM) approachof key pests. These efforts will promote and ensure the sustainable development of the tea ccosyst;m

    Survey of endoscopic skull base surgery practice patterns among otolaryngologists

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    Background Endoscopic skull base surgery (ESBS) is a rapidly expanding field. Despite divergent reported preferences for reconstructive techniques and perioperative management, limited data exist regarding contemporary practice patterns among otolaryngologists performing ESBS. This study aims to elucidate current practice patterns, primarily the volumes of cases performed and secondarily a variety of other perioperative preferences. Methods An anonymous 32-item electronic survey examining perioperative ESBS preferences was distributed to the American Rhinologic Society membership. Statistical significance between variables was determined utilizing Student t, chi-square, and Fisher exact tests. Results Seventy otolaryngologists completed the survey. The effective response rate was approximately 22.5%. Sixty percent of respondents were in full-time academic practice and 70% had completed rhinology/skull base fellowships. Annually, 43.3 mean ESBS cases were performed (29.1 private practice vs. 52.9 academic practice, P = .009). Academic practice averaged 24.1 expanded cases versus only 11 in private practice (P = .01). Of respondents, 55.7% stood on the same side as the neurosurgeon and 72.9% remained present for the entire case. Current procedural terminology coding and antibiotic regimens were widely divergent; 31.4% never placed lumbar drains preoperatively, while 41.4% did so for anticipated high-flow cerebrospinal fluid leaks. While considerable variation in reconstructive techniques were noted, intradural defect repairs utilized vascularized flaps 86.3% of the time versus only 51.3% for extradural repairs (P < 0.001). Major complications were rare. Postoperative restrictions varied considerably, with most activity limitations between 2–8 weeks and positive airway pressure use for 2–6 weeks. Most respondents started saline irrigations 0–2 weeks postoperatively. Conclusions Based on responses from fellowship- and non-fellowship-trained otolaryngologists in various practice settings, there remains considerable variation in the perioperative management of patients undergoing ESBS. Level of Evidence

    Effects of feeding intensity and dietary phosphorus content on breeding gilts

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    Calibrating Markov chain-based deterioration models for predicting future conditions of railway bridge elements

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    Existing nonlinear optimization-based algorithms for estimating Markov transition probability matrix (TPM) in bridge deterioration modeling sometimes fail to find optimum TPM values, and hence lead to invalid future condition prediction. In this study, a Metropolis-Hasting algorithm (MHA)-based Markov chain Monte Carlo (MCMC) simulation technique is proposed to overcome this limitation and calibrate the state-based Markov deterioration models (SBMDM) of railway bridge components. Factors contributing to rail bridge deterioration were identified; inspection data for 1,000 Australian railway bridges over 15 years were reviewed and filtered. The TPMs corresponding to a typical bridge element were estimated using the proposed MCMC simulation method and two other existing methods, namely, regression-based nonlinear optimization (RNO) and Bayesian maximum likelihood (BML). Network-level condition state prediction results obtained from these three approaches were validated using statistical hypothesis tests with a test data set, and performance was compared. Results show that the MCMC-based deterioration model performs better than the other two methods in terms of network-level condition prediction accuracy and capture of model uncertainties

    On the control of systems with input saturation or periodic disturbances

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    This thesis deals with two important problems in control theory and practice. The first problem is the windup problem in controllers where there exist non-linearities between the controller output and the process input. The first four parts of the thesis address this issue and in particular, anti-windup compensators to avoid controller windup are studied. The second problem, which is studied in Part V of the thesis, is the rejection of periodic disturbances and the tracking of periodic setpoints. In Part I we investigate a number of different anti-windup compensators available in the literature, and expose the observer property inherent in a class of such compensators. This observer property enables us to unify these anti-windup compensators as special cases of a general observer based anti-windup compensator. In Part II, a particular anti-windup compensator known as the conditioning technique is investigated, and an inherent weakness (short sightedness) in this method is demonstrated. To overcome the effect of the short sightedness and other limitations in the conditioning technique, a generalization is proposed, and its relationship to the other methods is investigated. In Part III, we have investigated the convergence properties of adaptive poleplacement controllers when there exists input saturation. The analysis is facilitated by using the anti-windup compensator based on the generalization proposed for conditioning technique in Part II. The analysis is limited to stable processes. Part IV addresses the problem of controller windup and the problem of directional change in controls for multi-input multi-output processes with input saturation. To avoid the windup problem, first the generalization in Part II for the conditioning technique is extended to the multivariable case. Then, using the geometric interpretation of the conditioning technique, further modifications based on inequality constraint optimization are introduced to reduce the effect of the directional change in control on output performance. In Part V, as an alternative to the controllers based on the internal model principle, a feedforward controller is derived to achieve complete decoupling of periodic disturbances and perfect tracking of periodic setpoints, even when the process is nonminimum phase. In particular, it is shown that this feedforward controller which is indeed a finite impulse response filter, can be obtained by solving a Diophantine identity. When the measurements are corrupted by noise, a tuned filter is utilized to improve the performance. To achieve fast disturbance estimation, especially when the shape of the periodic signal is slowly varying, a time-varying tuned filter is also proposed. However, the proposed tuned filter is strictly limited to the case where the disturbances are purely periodic in discrete-time.Godkänd; 1991; 20070429 (ysko)</p
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