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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.
401

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.
402

A framework for best practice environmental impact assessment follow-up : a case study of the Ekati Diamond Mine, Canada

Macharia, Sarah Njoki 19 May 2005 (has links)
Environmental Impact Assessment (EIA) is broadly defined as a systematic process that proactively examines the potential consequences of development actions. As a planning process, the longer-term objective of EIA is to contribute to sustainable development of the environment. EIA cannot meet its sustainability objective without a systematic follow-up program. Notwithstanding the benefits of a follow-up program, there is little guidance for best practices. The problem is that follow-up programs are not widely implemented in EIA and the lessons learned from experience have not been documented. This research explores the principles and characteristics of best-practice follow-up in an attempt to identify the lessons learned and issues raised from experiences in Canadas mining resource sector. A normative framework for doing follow-up is developed from the literature using these principles. Based on document analysis and semi-structured interviews, a case study of the Ekati Diamond Mine, Canadas first diamond mine, is evaluated based on the best practice principles, which advocate actions for success. The Ekati mine is meeting requirements in the best practice principles, as established in the best practice framework, which is outlined in part, in licenses obtained by Ekati. This is exemplified in BHPBs, use of hypothesis in impact prediction. However, there are normative principles and elements that are left out in Broken Hill Proprietary Billiton Ekatis follow-up programs. For example, there is some concern about the level to which local knowledge has been incorporated and the level to which monitoring of socio-economic elements is being carried out. Based on Ekatis experience, a number of new lessons emerge to inform the framework on best practice follow-up namely, that there is need for mandatory, non-ephemeral legislation on follow-up, that baseline data needs to be repeatedly collected after projects have started operations and that there is a need for firmer requirements if proponents are to exercise serious commitment to public involvement.
403

Omlastningsteminal - En studie av miljöeffekter vid införande av omlastningsterminal och ruttplaneringssystem i Kalmar kommun

Jina, Tina, Quist, Johanna, Svensson, Elise January 2010 (has links)
Title: Transshipment Terminal – A study of environmental effects from the introduction of a transshipment terminal and a route planning system in the municipality of Kalmar Examiner: Andersson, Petra Key words: Transshipment terminal, route planning, environmental impact Purpose: The study aims to examine how a transshipment terminal and a route planning system may have implications for the municipality of Kalmar from environmental concerns. Methodology: The thesis is a case study on the municipality of Kalmar. A positivistic -and an objectivistic approach have been used. The strategic approach that was used was quantitative. Theoretical perspectives: The thesis has mainly been based on theories of transshipment terminal, route planning and environmental impact, but also other relevant theories have been used. Emperical foundation: Empirical data has gathered through interviews with the municipality of Kalmar and its suppliers and from data that was obtained from them. The information has then been analyzed using the theoretical framework. Conclusions: By imposing a transshipment terminal and route planning for the municipality of Kalmar, the number of transports, transport distance and carbon dioxide emissions can be reduced. transshipment terminal can be analyzed, and how suppliers can change their routes when a transshipment terminal is inmplemented. Also where the transshipment terminal should be placed can be another subject to study. Suggestions for further research: The authors suggest that a deeper study of the total costs of
404

The effects of implementing a method to reduce anal sphincter ruptures

Pirhonen, Laura January 2011 (has links)
Aim of the study: The aim of this study was to measure the effects of a specific technique used when assisting vaginal delivery and intended to decrease anal sphincter ruptures. After measuring the effects, the direct costs of a rupture were calculated and finally the cost impact of the intervention was evaluated. Data and model: Data from deliveries before the intervention, from 2004, and after the intervention, from 2008, were used and a pre-test – post-test evaluation design was applied. The dependent variable was the presence or absence of a rupture and because the variable is binary a logit model was used. The independent variables consisted of twelve different factors considered to affect the number of ruptures. When only accounting for ruptures alone 123 of 2900 deliveries resulted in a sphincter ruptures which equals 4.24% of the total amount of deliveries. Results: When not controlling for any of the independent variables, the risk of getting a rupture decreased by 3.8 percentage points when using the method while assisting a delivery. On the other hand, when controlling for all of the independent variables and the use of the method, the risk of getting a rupture decreased by 2.5 percentage points, from 4.24% to 1.74%. Two different models were tested, one with the variable weeks and one without the same variable, due to the presence of correlation in the model. The total cost of ruptures for a year was calculated as $84,429,254 without the implementation of the method and $34,647,854 with the implementation. Total cost savings for society with the implementation of the method would then be $49,677,045. Conclusions: Implementation of the method is highly recommendable for both society and the women involved. Not only does the number of ruptures decrease due to the method but also the costs for society decreases dramatically.
405

A Study of Impact Factors among High School Students in Selecting Schools

Lin, Yao-Lung 10 September 2012 (has links)
The aim of the research is to explore the impact factors that the students of the private high school may consider. By so doing, we can understand the significant points that the private high school students may consider on the one hand and whether there exists any differences among the impact factors of choosing school from their diversity of backgrounds on the other hand. The survey is used in the research as the methodology; a survey tool is designed as ¡§The Impact Factors of the 12th and the 13th Grade Students in School Choosing.¡¨ The participants of the research are the 12th and the 13th grade students in a private school in Kaohsiung City. The data obtained would be further analyzed in terms of descriptive statistics, t-test, one-way ANOVA, and so on. The research discovers that: I. The ¡§curriculum and teaching factor¡¨ is the most significant among the impact factors of the private high school students in their school choosing. II. In the item of ¡§key person¡¦s factor¡¨ of the private high school students in their school choosing, ¡§my own choice¡¨ is the most significant. III. In the item of ¡§curriculum and teaching¡¨ of the private high school students in their school choosing, ¡§teacher¡¦s hardworking¡¨ is the most significant. IV. In the item of ¡§school counseling factor¡¨ of the private high school students in their school choosing, ¡§the peers¡¦ good relationship¡¨ is the most significant. V. In the item of the ¡§environmental equipment factor¡¨ of the private high school students in their school choosing, ¡§the air conditioning in the classroom¡¨ is the most significant. VI. In the item of ¡§the school marketing factor¡¨ of the private high school students in their school choosing, ¡§the reasonable tuition¡¨ is the most significant. VII. The science-majored private high school students consider the ¡§counseling factor¡¨ and the ¡§school marketing factor¡¨ more than the humanities-majored students do. VIII. The male private high school students consider the ¡§curriculum and teaching factor¡¨ and the ¡§counseling factor¡¨ more than the female students do. IX. The private high school students whose father¡¦s education is ¡§more than graduate school¡¨ consider the ¡§counseling factor¡¨ more than those whose father¡¦s education is ¡§college or university¡¨ do. X. The private high school students whose mother¡¦s education is ¡§college or university¡¨ consider the ¡§key person¡¦s factor,¡¨ ¡§curriculum and teaching factor,¡¨ and ¡§counseling factor¡¨ more than those whose mother¡¦s education is ¡§less than the (vocational) high school¡¨ do. XI. The private high school students whose mother¡¦s education is ¡§less than the (vocational) high school¡¨ consider the ¡§school marketing factor¡¨ more than those whose mother¡¦s education is ¡§more than graduate school¡¨ do. XII. The private high school students who live in ¡§the suburban area¡¨ in their school choosing factors consider ¡§the environmental equipment factor¡¨ more than those who live in ¡§the urban area of Fongshan District¡¨ do. According to the results, the research attempts to propose student recruiting strategies for the private schools.
406

Market reactions to animal disease: the case of bovine spongiform encephalopathy discoveries in North America

Hu, Rong 15 May 2009 (has links)
The increasing awareness of, and concern over, possible terrorist attacks using biological threats has increased attention and efforts for safeguarding U.S. agriculture. Whether intentional or unintentional, a biological event likely would cause substantial consequences well beyond the U.S. agricultural sector with considerable economic, social, and political costs. One significant impact would involve trade disruptions. This dissertation investigates biosecurity risk impacts with a focus on animal disease outbreaks using data from recent U.S. and Canada bovine spongiform encephalopathy (BSE) cases. An empirical study was carried out on the impact of the North American BSE cases. Using a time series approach, this study detected a significant structural break during the second half of 2003 when two BSE cases were confirmed in North America. Results showed that U.S. beef prices responded to the disruptions in cattle and beef trade caused by the BSE cases. The ban on beef and cattle imports from Canada and the ban on U.S. beef exports were major contributors to the fluctuation in beef prices. This showed that trade disruptions following the BSE discoveries in North America resulted in a supply shift and affected the movement of beef prices afterwards. The study did not find strong evidence that the 2003 North American BSE cases and associated trade disruptions greatly affected per capita beef consumption. In turn, a simulation study was conducted to examine the impact of major BSE outbreaks, associated trade disruptions, and demand shifts on U.S. welfare and the livestock industry. Six alternative scenarios were simulated and compared with the base scenario where there was no trade disruption and demand shift. The six scenarios consisted of various combinations of cattle and beef trade restrictions, livestock production adjustment, and beef demand shift. When beef and cattle trade, and market demand are greatly reduced in the wake of the BSE events in both Canada and the U.S., the impact on the U.S. welfare, meat trade, and regional livestock production would be the greatest. Beef price and production could reduce by 26% and 16% respectively. Regional impact on beef and livestock production would also be substantial in this case.
407

Is emotional intelligence worthwhile?: Assessing incremental validity and adverse impact

Rhodes, Dana Lanay 15 May 2009 (has links)
Emotional intelligence is defined as the ability to perceive emotion, understand emotion, facilitate thought with emotion, and regulate emotion. Considerable debate exists as to whether emotional intelligence adds incremental validity above more wellknown predictors of performance, namely the Big Five personality traits and cognitive ability. Furthermore, no theory directly specifies the roles of separate emotional intelligence (EI) dimensions in relationship to job performance. This paper offers several contributions: (a) a summary of theoretical links between EI and job performance, (b) meta-analytic incremental validity estimation for two different conceptualizations of emotional intelligence – labeled ability EI and mixed EI – over and above cognitive ability and Big Five personality composites, (c) estimation of Black-White and femalemale adverse impact attributable to the use of EI for selection purposes, and (d) a theoretical model of EI subdimensions, demonstrating that emotion regulation mediates the effects of emotion perception and emotion understanding on job performance, and that emotional competencies serve as partial mechanisms for the effects of Conscientiousness and cognitive ability on performance.
408

Using finite element structural analysis to study retroreflective raised pavement markers

Tong, Jiaxin 02 June 2009 (has links)
This thesis investigates the stress inside Retroreflective Raised Pavement Markers (RRPMs) under tire-marker impact and laboratory testing scenarios. Many RRPMs have poor durability although they meet certain standards of the existing laboratory tests. It has been suspected that the current testing procedures might not be adequate to decide the field performance of RRPMs. Thus, it is necessary to evaluate the existing laboratory testing procedures and develop additional ones that could simulate the field performance of RRPMs more accurately. The tire-marker impact on rigid and flexible pavement will be investigated to identify the critical locations and magnitudes of stress inside markers during the impact. Various external factors, such as tire loading, tire speed, contact angle and contact location, might have effects on the stress inside markers during the impact and be considered as critical factors when developing a laboratory test. On the other hand, RRPMs have different profiles in terms of height, lens slope, and size etc, which affect the structure and field performance as well. The study explores the stress inside markers during the impact by varying the external factors and marker profile. In addition, the interface forces between RRPMs and pavement surface will be studied. Furthermore, the tire-marker impact simulation on rigid and flexible pavement will be compared so that specific testing procedures can be distinguished based on pavement type. Finally, the existing laboratory tests will be examined and additional tests be recommended based on the tire-marker impact analysis. The researcher found that the critical compressive stress is produced at the top edges of the markers on both types of pavement, while the patterns of critical tensile stress can be different between the two types of pavement. In addition, tire loading and contact location were determined to have effect on the stress inside the markers. Furthermore, different loading rates should be used in laboratory test based on pavement type. Finally, the researcher evaluated four laboratory tests and found that each test has its merit but none of them can test RRPMs comprehensively, so it is recommended that the four tests are used together to test RRPMs.
409

Avoiding Earth Impacts Using Albedo Modification as Applied to 99942 Apophis

Margulieux, Richard Steven 2010 May 1900 (has links)
Current orbital solutions for 99942 Apophis predict a close approach to the Earth in April 2029. The parameters of that approach affect the future trajectory of Apophis, potentially leading to an impact in 2036, 2056, 2068, etc. The dynamic model used for this prediction does not account for non-gravitational perturbations including solar pressure and the Yarkovsky effect. Estimates of the displacement due to these perturbations range from -1500 to 1500km by 2029, comparable to 7? uncertainty in orbital solution. Uncertainties in physical characteristics stem from a lack of direct observations and a shortage of empirical data on similar objects. These perturbations, which stem from interactions with solar radiation, are directly related to the albedo of Apophis? surface. By modifying the average albedo of Apophis by 0.5%, between 4 and 15m of displacement can be effected between 2023 and 2029, rendering this method capable of avoiding all near-nominal solution keyholes. This modification is obtained by the deposition of electrostatically charged particles. These particles are charged via tribo-electrification and cure on the surface of Apophis creating a 30 micron thick layer of material with desired properties. This study found that a change in average albedo would nominally require 160kg of polytetrafluoroethylene (PTFE) to increase by 0.5% or 290kg of PTFE to decrease by 0.5%. The Apophis Exploration and Mitigation mission concept both improves accuracy of nongravitational perturbation models and delivers the albedo modification mechanism to Apophis, launching in 2021 and modifying albedo in 2023.
410

Modeling of Wave Impact Using a Pendulum System

Nie, Chunyong 2010 May 1900 (has links)
For high speed vessels and offshore structures, wave impact, a main source of environmental loads, causes high local stresses and structural failure. However, the prediction of wave impact loads presents numerous challenges due to the complex nature of the instant structure-fluid interaction. The purpose of the present study is to develop an effective wave impact model to investigate the dynamic behaviors of specific shaped elements as they impact waves. To achieve this objective, a wave impact model with a body swinging on a pendulum system is developed. The body on the pendulum goes through a wave free surface driven by gravity at the pendulum's natural frequency. The system's motion and impact force during the entire oscillation time beginning from the instant of impact are of interest. The impact force is calculated by applying von Karman's method, which is based on momentum considerations. The usual wave forces are presented in the Morison's equation and incorporated into dynamic systems with other wave forces. For each body shape, the dynamic system is described by a strongly nonlinear ordinary differential equation and then solved by a Runge-Kutta differential equation solver. The dynamic response behavior and the impact force time history are obtained numerically and the numerical results show support the selection of a pendulum model as an efficient approach to study slamming loads. The numerical prediction of this model is compared to previous experiments and classification society codes. Moreover, a basic design of wave impact experiments using this pendulum model is proposed to provide a more accurate comparison between numerical results and experimental data for this model. This design will also serve as a first look at the experimental application of the pendulum model for the purpose of forecasting slamming force.

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