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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.
21

Exposure to hand-arm vibration and its effects on workers at a mine rock drill repair and maintenance workshop / D.P. Visagie.

Visagie, Daniël Petrus January 2012 (has links)
In many occupations, exposure to hand-transmitted vibration (HTV) over a prolonged period causes various disorders involving the vascular, neural and musculoskeletal systems, collectively known as the hand-arm vibration syndrome (HAVS). It is a complex and potentially disabling chronic disorder of the upper extremities, especially of the hands. Numbness, tingling, reduced tactile discrimination, and impaired manipulative dexterity are often reported by workers exposed to HTV. The precise pathophysiological mechanism responsible for vascular injuries in HAVS has not yet been fully clarified; it seems to be multifactorial and highly complex. Interaction of neural signals, hormones, mediators and changes in the blood vessel itself appear to contribute to the development of such vascular injuries. This study aims to assess the risk of the hand-transmitted vibration exposure during pneumatic impact wrench operation in a rock drill repair and maintenance workshop at a South African platinum mine. A total of 8 workers working on a day to day basis with impact wrenches were available for this study. For each of the workers a control (not exposed to vibration) was selected on the basis of gender, ethnic group, smoking habits, age and body mass index (BMI). Grip force, dexterity and hand-eye co-ordination were tested on the workers and control group before and after work. Finger systolic blood pressure (FSBP) was also measured after cold provocation of the worker and control groups. Results have shown astatistically significant difference between the two groups with respect coordination, dexterity and FSBP after cold provocation. Vibration measurements shows three workers had values above the suggested ELV of 5 m/s² for an eight hour A (8) workday. With regards to dexterity, workers were capable to manipulate small objects better with their dominant right (vibration exposed) hand after work than before work. In contrast, it seems that the number of pegs correctly inserted by the controls is not uniformly affected by their 8 hour workday. The worker group showed a greater grip force than that of the control group, both before and after work.There was a statistically significant difference between the control and worker group with respect to the number of mistakes during the mirror trace and the time to complete this test only for the right hand. The difference in FSBP after cold provocation between the control and worker group observed is of medium importance when compared with effect sizes, however, there was no statistical significant difference. In this study, it was very difficult to make valid conclusions due to the limitations of a small sample size. A longitudinal study should be conducted preferably using newly appointed workers with no prior exposure to vibration and a sufficient control group to eliminate the effect other confounding variables such as general working conditions. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.
22

Exposure to hand-arm vibration and its effects on workers at a mine rock drill repair and maintenance workshop / D.P. Visagie.

Visagie, Daniël Petrus January 2012 (has links)
In many occupations, exposure to hand-transmitted vibration (HTV) over a prolonged period causes various disorders involving the vascular, neural and musculoskeletal systems, collectively known as the hand-arm vibration syndrome (HAVS). It is a complex and potentially disabling chronic disorder of the upper extremities, especially of the hands. Numbness, tingling, reduced tactile discrimination, and impaired manipulative dexterity are often reported by workers exposed to HTV. The precise pathophysiological mechanism responsible for vascular injuries in HAVS has not yet been fully clarified; it seems to be multifactorial and highly complex. Interaction of neural signals, hormones, mediators and changes in the blood vessel itself appear to contribute to the development of such vascular injuries. This study aims to assess the risk of the hand-transmitted vibration exposure during pneumatic impact wrench operation in a rock drill repair and maintenance workshop at a South African platinum mine. A total of 8 workers working on a day to day basis with impact wrenches were available for this study. For each of the workers a control (not exposed to vibration) was selected on the basis of gender, ethnic group, smoking habits, age and body mass index (BMI). Grip force, dexterity and hand-eye co-ordination were tested on the workers and control group before and after work. Finger systolic blood pressure (FSBP) was also measured after cold provocation of the worker and control groups. Results have shown astatistically significant difference between the two groups with respect coordination, dexterity and FSBP after cold provocation. Vibration measurements shows three workers had values above the suggested ELV of 5 m/s² for an eight hour A (8) workday. With regards to dexterity, workers were capable to manipulate small objects better with their dominant right (vibration exposed) hand after work than before work. In contrast, it seems that the number of pegs correctly inserted by the controls is not uniformly affected by their 8 hour workday. The worker group showed a greater grip force than that of the control group, both before and after work.There was a statistically significant difference between the control and worker group with respect to the number of mistakes during the mirror trace and the time to complete this test only for the right hand. The difference in FSBP after cold provocation between the control and worker group observed is of medium importance when compared with effect sizes, however, there was no statistical significant difference. In this study, it was very difficult to make valid conclusions due to the limitations of a small sample size. A longitudinal study should be conducted preferably using newly appointed workers with no prior exposure to vibration and a sufficient control group to eliminate the effect other confounding variables such as general working conditions. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.
23

Traffic Safety Assessment of Different Toll Collection Systems on Expressways Using Multiple Analytical Techniques

Abuzwidah, Muamer 01 January 2014 (has links)
Traffic safety has been considered one of the most important issues in the transportation field. Crashes have caused extensive human and economic losses. With the objective of reducing crash occurrence and alleviating crash injury severity, major efforts have been dedicated to reveal the hazardous factors that affect crash occurrence. With these consistent efforts, both fatalities and fatality rates from road traffic crashes in many countries have been steadily declining over the last ten years. Nevertheless, according to the World Health Organization, the world still lost 1.24 million lives from road traffic crashes in the year of 2013. And without action, traffic crashes on the roads network are predicted to result in deaths of around 1.9 million people, and up to 50 million more people suffer non-fatal injuries annually, with many incurring a disability as a result of their injury by the year 2020. To meet the transportation needs, the use of expressways (toll roads) has risen dramatically in many countries in the past decade. In fact, freeways and expressways are considered an important part of any successful transportation system. These facilities carry the majority of daily trips on the transportation network. Although expressways offer high level of service, and are considered the safest among other types of roads, traditional toll collection systems may have both safety and operational challenges. The traditional toll plazas still experience many crashes, many of which are severe. Therefore, it becomes more important to evaluate the traffic safety impacts of using different tolling systems. The main focus of the research in this dissertation is to provide an up-to-date safety impact of using different toll collection systems, as well as providing safety guidelines for these facilities to promote safety and enhance mobility on expressways. In this study, an extensive data collection was conducted that included one hundred mainline toll plazas located on approximately 750 miles of expressways in Florida. Multiple sources of data available online maintained by Florida Department of Transportation were utilized to identify traffic, geometric and geographic characteristics of the locations as well as investigating and determination of the most complete and accurate data. Different methods of observational before-after and Cross-Sectional techniques were used to evaluate the safety effectiveness of applying different treatments on expressways. The Before-After method includes Naive Before-After, Before-After with Comparison Group, and Before-After with Empirical Bayesian. A set of Safety Performance Functions (SPFs) which predict crash frequency as a function of explanatory variables were developed at the aggregate level using crash data and the corresponding exposure and risk factors. Results of the aggregate traffic safety analysis can be used to identify the hazardous locations (hot spots) such as traditional toll plazas, and also to predict crash frequency for untreated sites in the after period in the Before-After with EB method or derive Crash Modification Factors (CMF) for the treatment using the Cross-Sectional method. This type of analysis is usually used to improve geometric characteristics and mainly focus on discovering the risk factors that are related to the total crash frequency, specific crash type, and/or different crash severity levels. Both simple SPFs (with traffic volume only as an explanatory variable) and full SPFs (with traffic volume and additional explanatory variable(s)) were used to estimate the CMFs and only CMFs with lower standard error were recommended. The results of this study proved that safety effectiveness was significantly improved across all locations that were upgraded from Traditional Mainline Toll Plazas (TMTP) to the Hybrid Mainline Toll Plazas (HMTP) system. This treatment significantly reduced total, Fatal-and-Injury (F+I), and Rear-End crashes by 47, 46 and 65 percent, respectively. Moreover, this study examined the traffic safety impact of using different designs, and diverge-and-merge areas of the HMTP. This design combines either express Open Road Tolling (ORT) lanes on the mainline and separate traditional toll collection to the side (design-1), or traditional toll collection on the mainline and separate ORT lanes to the side (design-2). It was also proven that there is a significant difference between these designs, and there is an indication that design-1 is safer and the majority of crashes occurred at diverge-and-merge areas before and after these facilities. However, design-2 could be a good temporary design at locations that have low prepaid transponder (Electronic Toll Collection (ETC)) users. In other words, it is dependent upon the percentage of the ETC users. As this percentage increases, more traffic will need to diverge and merge; thus, this design becomes riskier. In addition, the results indicated significant relationships between the crash frequency and toll plaza types, annual average daily traffic, and drivers* age. The analysis showed that the conversion from TMTP to the All-Electronic Toll Collection (AETC) system resulted in an average reduction of 77, 76, and 67 percent for total, F+I, and Property Damage Only (PDO) crashes, respectively; for rear end and Lane Change Related (LCR) crashes the average reductions were 81 and 75 percent, respectively. The conversion from HMTP to AETC system enhanced traffic safety by reducing crashes by an average of 23, 29 and 19 percent for total, F+I, and PDO crashes; also, for rear end and LCR crashes, the average reductions were 15 and 21 percent, respectively. Based on these results, the use of AETC system changed toll plazas from the highest risk sections on Expressways to be similar to regular segments. Therefore, it can be concluded that the use of AETC system was proven to be an excellent solution to several traffic operations as well as environmental and economic problems. For those agencies that cannot adopt the HMTP and the AETC systems, improving traffic safety at traditional toll plazas should take a priority. This study also evaluates the safety effectiveness of the implementation of High-Occupancy Toll lanes (HOT Lanes) as well as adding roadway lighting to expressways. The results showed that there were no significant impact of the implementation of HOT lanes on the roadway segment as a whole (HOT and Regular Lanes combined). But there was a significant difference between the regular lanes and the HOT lanes at the same roadway segment; the crash count increased at the regular lanes and decreased at the HOT lanes. It was found that the total and F+I crashes were reduced at the HOT lanes by an average of 25 and 45 percent, respectively. This may be attributable to the fact that the HOT lanes became a highway within a highway. Moreover adding roadway lighting has significantly improved traffic safety on the expressways by reducing the night crashes by approximately 35 percent. Overall, the proposed analyses of the safety effectiveness of using different toll collection systems are useful in providing expressway authorities with detailed information on where countermeasures must be implemented. This study provided for the first time an up-to-date safety impact of using different toll collection systems, also developed safety guidelines for these systems which would be useful for practitioners and roadway users.
24

"Framför mig stod den vackraste man jag någonsin sett.” : Kvinnliga drag, egenskaper och funktioner hos manliga karaktärer i fantasy-romaner för unga vuxna / ”Standing before me was the most beautiful man I’d ever seen.” : Female traits, qualities and functions of male characters in fantasy-novels for young adults

Darstedt, Olivia January 2021 (has links)
The current paper is a study of the male characters Simon and Jace from Cassandra Clare's City of Bones (2010), and the characters Tamlin and Rhysand from Sarah J. Maas’ A Court of Thorns and Roses (2015). The main aim is to examine whether the characters in these fantasy novels for young adults have traits and functions that previously have been used to describe and portray female characters. The study discovered among other things that vulnerability and sensitivity could be found in all the characters, especially when danger was upon them or their loved ones. Simon was also the only character that was not portrayed with skills in combat, which was mocked by the other male characters but not by the female protagonist. The two male characters in A Court of Thorns and Roses were also portraited as sexual objects in the novel, and Rhysand was exposed to sexual abuse by the novel’s antagonist, which can be seen as stereotypical female trait. The male character’s function in the novels was to have a folie function to each other, and be a love interest, a confidant, and a choir to the female protagonist. The male characters in the novels were also the ones who needed to be rescued by the female characters, and thereby found themselves in a female position.

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