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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.
461

Numerical Modeling of Tsunami Bore Attenuation and Extreme Hydrodynamic Impact Forces Using the SPH Method

Pich­é, Steffanie 16 January 2014 (has links)
Understanding the impact of coastal forests on the propagation of rapidly advancing onshore tsunami bores is difficult due to complexity of this phenomenon and the large amount of parameters which must be considered. The research presented in the thesis focuses on understanding the protective effect of the coastal forest on the forces generated by the tsunami and its ability to reduce the propagation and velocity of the incoming tsunami bore. Concern for this method of protecting the coast from tsunamis is based on the effectiveness of the forest and its ability to withstand the impact forces caused by both the bore and the debris carried along by it. The devastation caused by the tsunami has been investigated in recent examples such as the 2011 Tohoku Tsunami in Japan and the Indian Ocean Tsunami which occurred in 2004. This research examines the reduction of the spatial extent of the tsunami bore inundation and runup due to the presence of the coastal forest, and attempts to quantify the impact forces induced by the tsunami bores and debris impact on the structures. This research work was performed using a numerical model based on the Smoothed Particle Hydrodynamics (SPH) method which is a single-phase three-dimensional model. The simulations performed in this study were separated into three sections. The first section focused on the reduction of the extent of the tsunami inundation and the magnitude of the bore velocity by the coastal forest. This section included the analysis of the hydrodynamic forces acting on the individual trees. The second section involved the numerical modeling of some of the physical laboratory experiments performed by researchers at the University of Ottawa, in cooperation with colleagues from the Ocean, Coastal and River Engineering Lab at the National Research Council, Ottawa, in an attempt to validate the movement and impact forces of floating driftwood on a column. The final section modeled the movement and impact of floating debris traveling through a large-scale model of a coastal forest.
462

Screening of EIA in the Free State Province : a comparative analysis between the 1997 and 2006 EIA Regulations / C.N.J. Welman

Welman, Coert Nicolaas Jacobus January 2008 (has links)
Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2009.
463

Mechanized clam harvesting for coastal British Columbia: environmental implications.

Stirling, David 23 December 2011 (has links)
For certain shellfish species, a mechanical harvester has the potential to greatly reduce harvesting costs. Traditionally, hand rakes are used in shellfish harvesting in British Columbia. In order to determine if it is environmentally feasible to use a mechanical harvester, an environmental assessment on mechanical harvesting and traditional harvesting needs to occur for comparison. In July 2008, a preliminary oceanographic assessment was conducted at three study sites in Baynes Sound. Each of the three study sites contained a mechanical and manual harvest plot and reference stations. Sampling stations were established at fixed positions within each plot and at four positions along a downstream transect (following the dominant current direction.) Surveys were conducted 24 hours pre-harvest, immediately post-harvest, and 24 hours post-harvest. Parameters included in situ sediment sulphides, eH (REDOX), sediment grain size (SGS), visual condition (digital imagery), sedimentation (silt flux) and sediment macro-fauna. Results show only localized environmental effects associated with each harvest approach; with no significant difference documented between the manual and mechanical harvesting methods on the study beaches. These results indicate the use of a mechanical shellfish harvester is as environmentally sound as the traditional method of hand harvesting, and poses no additional environmental risks. Introducing mechanization in shellfish harvesting will allow shellfish producers to reduce costs and increase profits, making the British Columbian shellfish industry more competitive with other suppliers. / Graduate
464

The ecological limits of aquaculture: Comparative performance of salmon production systems

Ethier, Valerie 26 April 2013 (has links)
Aquaculture is one of the fastest growing animal protein production industries and accounted for 47% of the world’s food fish consumption in 2010. Aquaculture production is expected to increase to compensate for projected shortfalls in seafood supply by capture fisheries. Current assessments and scenarios predicting the outcome of this increased production have limited scope and ability to distinguish alternative courses of action. Using the Global Aquaculture Performance Index (GAPI) as a starting point, I have developed an ecologically comprehensive and quantitative farm level assessment. I selected salmon as the candidate to compare production scenarios due to being economically important, data rich and farmed in a diversity of production systems. In applying the farm-level assessment to conventional net-pen salmon production and four alternative systems, I determined the ecological impact per unit of production to be significantly different. It is possible to produce a greater volume of fish for less ecological impact. While there are benefits and trade-offs in the alternative production systems, the results indicate that projected food fish demands can be met in a more sustainable manner. The Farm Level Aquaculture Performance Index (FLAPI) provides a quantitative, performance-based tool that accounts for all ecological impacts and the resulting assessments can be used to benchmark and guide future development of aquaculture. / Graduate / 0792
465

Träningens betydelse för den självskattade hälsan : Vikten av arbetsgivarens engagemang

Bergqvist, Ulrika January 2014 (has links)
Med bakgrund av träningens betydelse för upprätthållandet av individens hälsa har denna studie riktats till att undersöka huruvida träningen bidrar till en bättre självskattad hälsa, SRH, eller inte och med hänsyn till träning tillhandahållen av arbetsgivaren eller annan träning. Metoden var kvantitativ med totalt 74 deltagare mellan 25-65 år, 54 var kvinnor. De kom från tre olika företag i Sverige inom två olika yrkesgrupper. Datainsamlingen skedde via en egen uppförd enkät som bestod av 11 frågor och några underfrågor. Deltagarna skattade sin hälsa utifrån en femgradig skala och SPSS användes för sammanställning av resultaten. Studien påvisade ett samband mellan SRH och om man tränade utan hjälp från arbetsgivaren. Det fanns även ett samband mellan SRH och träning oavsett om man tränade med eller utan arbetsgivarens hjälp. Resultaten diskuterades utifrån att tillgängligheten på träningen har en tendens till minskad betydelse med åldern.
466

The economic impact of manufacturing multinational investment in the UK and its regions : the explanatory variables

Williams, David Arthur January 1999 (has links)
No description available.
467

A methodology for the life cycle and sustainability analysis of manufacturing processes

Culaba, Alvin B. January 1996 (has links)
No description available.
468

Rotating machinery reliability

Moss, T. R. January 1999 (has links)
No description available.
469

Neck Response in Out of Position Rear Impact Scenarios

Shateri, Hamed 25 September 2012 (has links)
Whiplash injuries occur in automotive crashes and may cause long term health issues such as headache, neck pain, and visual and auditory disturbance. Whiplash-Associated Disorders are very costly and can impair the quality of human lives. Most studies focus on whiplash injuries that occur in neutral position head postures, although there is some evidence in the literature that non-neutral head posture can significantly increase the persistence of symptoms on patients. Crash dummies have limited biofidelity particularly for out-of-position scenarios and the current neck injury criteria were not derived for situations at which the head motion is not through the sagittal plane. Therefore Finite Element Methods provide an important tool that can be used to predict injury in different impact scenarios. The Finite Element model which was used for this study was previously developed at the University of Waterloo representing a 50th percentile male. The model had been previously validated at the segment level in extension, flexion, tension, and axial rotation. The full cervical spine model was validated in frontal and rear impact as well as tension. Since the final validation of the model, the ligament properties of the upper cervical spine and the muscle implementations had been improved to enhance the biofidelity of the model. To further improve the model, the addition of laxities to the ligaments of the upper cervical spine was studied. Several studies were performed based on the experiments in the literature to determine appropriate laxities for the upper cervical spine model. First, the laxities of -2 to 4 mm on all the ligaments were studied on the segment level of the model to find their effect on the failure force and displacement to failure in extension, flexion, tension, and axial rotation. The model development then went through a series of iterations in order to achieve laxity values that satisfied the failure force and displacement to failure reported in the literature for the four loading cases. Finally the laxities were used on a full cervical spine model and tested in physiological range of motion in extension, flexion, axial rotation, and lateral bending. The laxities were optimized using an iterative process. The results of this study provided laxity values that were acceptable in both segments level failure study and full cervical spine physiological range of motion study. The model was also validated against literature in impact scenarios. Using a cadaver experiment of 7 g rear impact, the global kinematics of the cervical spine was verified against the literature. The model provided good agreement with the head kinematics and relative rotations between the vertebrae for the cadaver tests. An 8 g rear impact cadaver test was used to validate the ligament strains and disc shear strains. For the anterior longitudinal ligament, the capsular ligament, and the disc shear strains, the model results were within one standard deviation of the literature in the majority of cervical spine regions that were reported. The model was also validated against volunteer low severity rear impact to verify the active musculature in the cervical spine. The head kinematics was generally within the boundaries that were reported by the literature. The model was compared to an experiment that used cadavers to investigate non-neutral rear impact scenarios. This experiment used cables and springs to replicate the passive behaviour of the musculature. The model showed good agreement with the extension and axial rotation results in both head kinematics and relative vertebrae rotations. The flexion and lateral bending results were not similar to the experimental data; attributed to the difference in muscle implementation between the two models. A total of 24 simulations were completed to find the effect of impact severity, axial rotation, and muscle activations on ligament strains during out-of-position rear impacts. The results illustrated that in general, ligament strains increased with the severity of impact and decreased with muscle activation. In out-of-position scenarios, the strains increased in some of the ligaments. An increase to the ligament strain as a result of non-neutral posture was mostly visible in the capsular ligaments of the upper cervical spine. The alar ligament and the apical ligaments of the upper cervical spine may fail in out-of-position at high rear impact scenarios. Recommendations for future work on the cervical spine Finite Element model includes the validation of the musculature and the usage of the muscles to rotate the head to a desired position to improve the biofidelity of the model and the results in out-of-position rear impacts. Further optimization of the laxities of the upper cervical spine can increase the biofidelity in this region. The modeling of the vertebral arteries into the FE model can help investigate whether out-of-position can increase the chance of injury of this region. The effect of flexion, extension, lateral bending, and their combination with axial rotation and the study of frontal and side impacts can be helpful in design of safer headrests for vehicles.
470

Identifying Behavioural Implications of Source Code Changes

El-Sayed, Abdullah January 2013 (has links)
The dynamic behaviour of a software system changes as a consequence of developer’s static source code modifications. In this thesis, we improve upon a previous approach that combines static and dynamic analyses to categorize behavioural changes by greatly improving its accuracy through polymorphic mapping. We further refine the previous model by introducing a change-centric state transition model that captures the flow of call pairs among different partitions based on static and dynamic call graphs. We also extend the approach by incorporating complete dynamic call stacks into the analysis. Finally, we perform a longitudinal analysis of three software systems to categorize how they have dynamically evolved across 100 program versions. In our evaluation, the polymorphic mapping algorithm decreased mismatches between the static and dynamic analyses by 53%. In particular, we decreased the mismatch by 71% in the most important category of changes from the developer’s point of view. We found that developers introduce new behaviour more often than eliminating old behaviour. Our results show that developers are more likely to remove unexecuted/dead code than code that is executed dynamically. In terms of change types, we found that changes made to fix defects encountered the least inconsistent and unexpected behaviour, while changes made to add new functionality experienced the highest unexecuted behaviour. Finally, we argue that augmenting the dynamic analyses with call stacks provides useful information that helps developers analyze the implications of the call pairs highlighted by our analyses.

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