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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Engineered Cartilage on Chitosan Calcium Phosphate Scaffolds for Osteochondral Defects

Gottipati, Anuhya 07 May 2016 (has links)
Articular cartilage provides an almost frictionless surface for the articulating ends of the bone. Cartilage functions to lubricate and transmit compressive forces resulting from joint loading and impact. If the cartilage is damaged, through traumatic injury or disease, it lacks the ability of self-repairing as the tissue lacks vascular system. If the injuries to articular cartilage are left untreated, they may progress to Osteoarthritis. Osteoarthritis, a degenerative disease, is one of the leading disabilities in the United States. Tissue engineering has the potential to regenerate healthy hyaline cartilage, which can alleviate pain and restore the functions of normal tissue. This study explores the production of engineered cartilage on top of composite calcium phosphate scaffold. The current research is related to a biphasic approach to cartilage tissue engineering — in which one layer supports to form subchondral bone (osteogenesis) and another supports cartilage formation (chondrogenesis). Chondrocyte and bone marrow-derived stem cell attachment to chitosan will be investigated for producing a bilayered construct for osteochondral repair. The main objectives of my research include the following: attachment and proliferation of human mesenchymal stem cells on chitosan calcium phosphate scaffolds, techniques to create a biphasic construct, the effect of coating chitosan calcium phosphate scaffolds with type I collagen and determining the ideal bead size for making chitosan calcium phosphate scaffolds.
242

Modeling Atomic Defects in a Two-Dimensional Lennard-Jones Lattice Using Molecular Dynamics Simulations

Tuesday, Andrew J. 16 May 2012 (has links)
No description available.
243

Investigation of Material, Process, and Environmental Factors in Bubble Defect Formation for Labels of Bottled Essential Oils

Andrus, Joseph Lloyd 17 June 2022 (has links)
Labeling of consumer products is not only required by regulatory bodies for product identification, but it also serves as a symbol of product quality and prestige. Bubbles under the label are unsightly and impact customer satisfaction. Pressure Sensitive Adhesive (PSA) labels currently make up more than eighty percent of all labels in the market today, yet little research could be found addressing causes of bubbling in an industrial setting. A root cause analysis for bubble development included four aspects: label application, environmental conditions of shipping and storage, defects in glass bottle geometry, and oil contamination. The most significant findings from each area were as follows: Label Application. Force and contact time were confirmed to be significant factors in reducing label bubbling. The equipment settings directly related to these factors should be controlled and monitored. Environmental Conditions. None of the environmental conditions caused growth or appearance of additional bubbles as was the hypothesis. All 4 test conditions had a significant Paired T-test but in the reduction of bubble size. Glass Defects. A random sample of bottles showed very poor capability of the bottle dimensions. However, low capability to produce within specification limits does not necessarily lead to bubbling. A direct comparison test was done to compare diameters and variation from bubbled bottles to non-bubbled. No measurements that could reasonably be related to bubbles caused by glass defectiveness were statistically different. Oil Contamination. Initial data analysis showed that certain oil types had a higher chance of causing bubbling. However, after a controlled experiment was performed, the results were inconclusive that oil contamination pre or post-labeling could cause bubbling in isolation. The experiment did confirm the importance of sufficient pressure in the label application process.
244

Calculation of the Entropy of a Copper Lattice Containing Random Mass Defects

Woodside, Robert 09 1900 (has links)
<p> Entropy of mixing for random mass defects is examined and equations for the phonon contribution are developed. The Green's function method used gives the entropy change due to the phonons at all temperatures, but for experimental comparison the high temperature region is used. There simple formulae obtain, but the mass defect is not sufficient to account for the observed entropy changes. This suggests that further work is necessary. </p> / Thesis / Master of Science (MSc)
245

Automatic interpretation of computed tomography (CT) images for hardwood log defect detection

Li, Pei 18 November 2008 (has links)
This thesis describes the design of an image interpretation system for the automatic detection of internal hardwood log defects. The goal of the research is that such a system should not only be able to identify and locate internal defects of hardwood logs using computed tomography (CT) imagery, but also should be able to accommodate more than one type of wood, and should show potential for real-time industrial implementation. This thesis describes a new image classification system that utilizes a feed forward artificial neural network as the image classifier. The classifier was trained with back-propagation, using training samples collected from two different types of hardwood logs, red oak and water oak. Pre-processing and post-processing are performed to increase the system classification performance, and to make the system be able to accommodate more than one wood type. It is shown in this thesis that such a neural-net based approach can yield a high classification accuracy, and it shows a high potential for parallelism. Several possible design alternatives and comparisons are also addressed in the thesis. The final image interpretation system has been successfully tested, exhibiting a classification accuracy of 95% with test images from four hardwood logs. / Master of Science
246

Analysis of Red Oak Timber Defects and Associated Internal Defect Area for the Generation of Simulated Logs

Winn, Matthew F. 30 December 2002 (has links)
Log sawing simulation computer programs can be a valuable tool for training sawyers as well as for testing different sawing patterns. Most available simulation programs rely on databases from which to draw logs and can be very costly and time-consuming to develop. In this study, a computer program was developed that can accurately generate random, artificial logs and serve as an alternative to using a log database. One major advantage of using such a program is that every log generated is unique, whereas a database is finite. Real log and external defect data was obtained from the Forest Service Northeastern Research Station in Princeton, West Virginia for red oak (Quercus rubra, L.) logs. These data were analyzed to determine distributions for log and external defect attributes, and the information was used in the program to assure realistic log generation. An attempt was made to relate the external defect attributes to internal defect characteristics such as volume, depth, and angle. CT scanning was used to obtain internal information for the five most common defect types according to the Princeton log data. Results indicate that external indicators have the potential to be good predictors for internal defect volume. Tests performed to determine whether a significant amount of variation in volume was explained by the predictor variables proved significant for all defect types. Corresponding R2 values ranged from 0.39 to 0.93. External indicators contributed little to the explanation of variation in the other dependent variables. Additional predictor variables should be tested to determine if further variation could be explained. / Master of Science
247

Odpovědnost za vady v obchodních závazkových vztazích / Liability for defects in business transactions

Matějíček, Pavel January 2015 (has links)
The topic of this thesis is liability for defects in business transactions, or using the terminology of the effective Civil Code, obligations from non-performance. Rights from non- performance are one of the most important legal instruments regarding liability, together with liability for damage and liability for delay, all arising from pecuniary contracts, mainly from purchase contracts and contracts for work. With respect to the elapsed recodification of civil law, obligations arising from non- performance are no longer subject to two codes (in Act No. 40/1964 Coll., Civil Code and in Act No. 513/1991 Coll., Commercial Code), they are now governed only by Act No. 89/2012 Coll., the effective Civil Code. Civil code and its provisions are therefore the main part of this thesis. Moreover, some parts of the thesis contain comparison of the effective Civil Code to the preceding legislation, i.e. the Commercial Code, and to some international treaties as well. The first chapter, which follows right after the preface, contains sources of this thesis. The second chapter deals with the concept of obligations arising from non-performance, compares them to other areas of civil law dealing with liability, and later deals with the concept of commercial obligation. The third chapter talks about the provisions...
248

Measurement of stress and defects in mild steel and nickel by magnetoacoustic emission.

January 1994 (has links)
by Lo, Chi Ho Chester. / Title also in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 159-163). / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.iv / List of Figures --- p.vii / List of Tables --- p.xii / Chapter Chapter One --- Introduction --- p.1 / Chapter Chapter Two --- Domain Theory --- p.8 / Chapter 2.1 --- Energies in Magnetic Domain Structure --- p.8 / Chapter 2.2 --- Domains in Iron and Nickel --- p.13 / Chapter 2.3 --- Magnetization Process --- p.15 / Chapter 2.4 --- Effect of Applied Stress --- p.19 / Chapter Chapter Three --- Magnetoacoustic Emission --- p.25 / Chapter 3.1 --- Models of MAE --- p.25 / Chapter 3.1.1 --- Discontinuous Wall Motion --- p.25 / Chapter 3.1.2 --- Displacement Model --- p.28 / Chapter 3.1.3 --- DW Creation and Annihilation --- p.30 / Chapter 3.1.4 --- Combined Model of MAE --- p.31 / Chapter 3.2 --- MAE and Magnetic Induction --- p.34 / Chapter 3.2.1 --- Eddy Current Shielding --- p.34 / Chapter 3.2.2 --- Magnetic Reluctance Calculation --- p.35 / Chapter Chapter Four --- Experiments / Chapter 4.1 --- Instrumentation --- p.40 / Chapter 4.1.1 --- Introduction --- p.40 / Chapter 4.1.2 --- Basic Setup --- p.41 / Chapter 4.1.3 --- Arrangement for Stress Measurement --- p.46 / Chapter 4.1.4 --- Specimen Preparation --- p.43 / Chapter 4.2 --- Methodology / Chapter 4.2.1 --- The Fundamental Study of MAE --- p.53 / Chapter 4.2.1.1 --- Effects of Demagnetizing and Stray Fields on MAE --- p.53 / Chapter 4.2.1.2 --- Dependence of MAE on Frequency of Applied Field --- p.55 / Chapter 4.2.1.3 --- Dependence of MAE on Specimen Thickness and Width --- p.55 / Chapter 4.2.2 --- Stress Measurement --- p.58 / Chapter 4.2.2.1 --- Effect of Uniaxial Stress on MAE --- p.58 / Chapter 4.2.2.2 --- Effect of Biaxial Stresses on MAE --- p.58 / Chapter 4.2.3 --- Defect Detection --- p.60 / Chapter 4.2.3.1 --- Nickel --- p.60 / Chapter 4.2.3.2 --- Mild Steel --- p.61 / Chapter Chapter Five --- Results and Discussion / Chapter 5.1 --- Effects of Demagnetizing and Stray Fields on MAE --- p.63 / Chapter 5.1.1 --- MAE Profiles --- p.63 / Chapter 5.1.2 --- Magnetic Reluctance Calculation --- p.68 / Chapter 5.1.3 --- Effect of Annealing --- p.74 / Chapter 5.1.3.1 --- Experimental Results --- p.74 / Chapter 5.1.3.2 --- Discussion --- p.77 / Chapter 5.1.3.3 --- Magnetic Reluctance Calculation --- p.78 / Chapter 5.2 --- Dependence of MAE on Frequency of Applied Field --- p.83 / Chapter 5.2.1 --- Experimental Results --- p.83 / Chapter 5.2.2 --- Theoretical Consideration --- p.88 / Chapter 5.3 --- Dependence of MAE on Specimen Thickness and Width --- p.96 / Chapter 5.3.1 --- Experimental Results --- p.96 / Chapter 5.3.2 --- Theoretical Consideration --- p.99 / Chapter 5.4 --- Effects of Uniaxial and Biaxial Stresses on MAE --- p.107 / Chapter 5.4.1 --- Effect of Uniaxial Stress --- p.107 / Chapter 5.4.1.1 --- Experimental Results --- p.107 / Chapter 5.4.1.2 --- Discussion --- p.116 / Chapter 5.4.2 --- Effect of Biaxial Stresses --- p.120 / Chapter 5.4.2.1 --- Study on Mild Steel Specimen --- p.120 / Chapter 5.4.2.2 --- Study on Nickel Specimen --- p.132 / Chapter 5.5 --- Defect Detection by MAE --- p.137 / Chapter 5.5.1 --- Study on Nickel Specimen --- p.137 / Chapter 5.5.1.1 --- Experimental Results --- p.137 / Chapter 5.5.1.2 --- Discussion --- p.140 / Chapter 5.5.2 --- Study on Mild Steel Specimen --- p.142 / Chapter 5.5.2.1 --- Experimental Results --- p.142 / Chapter 5.5.2.2 --- Discussion --- p.151 / Chapter Chapter Six --- Conclusions and Suggestions for Further Studies --- p.153 / References --- p.159
249

Bubble formation during solidification of a liquid film

Lin, Chun-Yen 20 July 2011 (has links)
Surface patterns of bead defects such as humping, gouged and rippling after solidification during laser and electron processing and different welding processes are systematically and quantitatively studied in this project. These defects usually accompanying with porosity, undercut, segregation, stress concentration, etc. seriously reduce the properties and strength of the surface heat treatment and weld joint. In order to improve quality, assure mass production and repeatability and reduce costs, it is necessary to understand their mechanisms. Although the defects have been extensively studied in the past, systematical, penetrative and quantitative understanding of their formation from thermal, physics, and pattern selection viewpoints are limited.The study include thermocapillary force, evaporation, and phase changes between solid-liquid and liquid-gas phases by introducing energy equation and interfacial and kinematic boundary conditions to simulate realistic processes.
250

The free surface deformation affected by a two-dimensional thermocapillary flow

Su, Heng-yi 27 August 2012 (has links)
This project is to explore the manufacturing and processing of laser or electron beam, formed on the surface morphology after curing and processing parts, such as surfacefilled, depression, or the formation of ripples; These reactions will directly affect the surface heat treatment and welding quality of thefinished product This study to consider the mass, momentum and energy equations, the introduction of theinterface and boundary conditions to simulate the real process In order to promote quality stability, and a large amount of production capacity and reduce costs, we must understand the institutions of the reaction In this thesis, the phase field method (Phase-field method) (Two-phase flow) two-phase flow simulation of metal surface by a concentrated source of heat melt the transient heat flow behavior

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