The railroad industry is responsible for the mass transport of a vast numbers of goods throughout the United States. As needs and capabilities of the railroad industry have changed, the interest in reducing the resistance of locomotives and railcars has increased. This has become paramount as fuel prices have increased in recent years. Resistant forces can result from friction in mechanical components and aerodynamic drag of the moving train. As the average traveling speeds of trains have increased, aerodynamics are contributing a larger fraction of the overall resistance. For this reason, the aerodynamic profiles of trains have become a topic of research. Furthermore, current manufacturing practices of railcars provide an opportunity for research in modifications that reduce the aerodynamic drag. This thesis reports on research that has been done to reduce aerodynamic drag on automobile-carrying railcars. Data was collected by placing G-scale (1/29) models into a wind tunnel with a 0.74 m^2 test section. These models were tested for Reynolds Numbers ranging from approximately 2.05 x 10^5 to 2.79 x 10^5. Modifications were made to the models with the intention of reducing the drag. The profile features of the auto-carrying railcars were reviewed and three regions were chosen to be the focus of this study. The selected regions are the roof, side panels and structural chassis region. Special attention was given to the regulations of the railroad industry to ensure the tested modifications would be candidates for implementation. From the data, it was determined that drag could be reduced by modifying or covering the roof, side panels and chassis structure by nominally 20%, 5% and 15% respectively.

Wrist surgery is a common method for treating carpal tunnel syndrome (CTS) although few studies have examined patient outcomes or predictive correlates of such procedures. The objectives of this study were to characterize Utah workers who received surgery for CTS in terms of relevant presurgical and outcome variables and to identify presurgical correlates of patient outcomes. Participants were 75 Utah workers' compensation patients who underwent surgery for CTS from 1999-2002 and were at least 6 months postsurgery at time of follow-up. A retrospective cohort design was utilized consisting of a review of presurgical medical records and a postsurgical telephone survey. Presurgical variables included: gender, age, history of depression, and litigation status. Correlational analyses revealed that age and lawyer involvement were consistent significant predictors of poorer outcomes. The importance of conceptualizing CTS surgery patient outcomes from a biopsychosocial perspective is discussed.

This thesis is an experimental study of spin dependent transport in nanoscale ferromagnetic tunnel junction arrays and lateral multi-terminal devices with normal metal and superconducting spin transport channels. Two-, three-, and five-junction arrays have been fabricated in the form of lateral circuits and characterized using variable temperature magneto-transport measurements. The smallest inter-junction separation achieved was 65 nm. No significant enhancement in the sequential magneto-resistance (MR) was observed, which is attributed to the combined effect of short spin diffusion length in the ferromagnetic electrodes and high resistance of the tunnel barriers used. A substantially weaker bias dependence of the MR is observed for double junctions than for single junctions, consistent with the theoretical expectations. Spin diffusion and relaxation in one-dimensional normal metal channels is studied using a novel multi-terminal device. The device has multiple ferromagnetic detector electrodes for an in-situ determination of the spin transport parameters. Such configuration has a great advantage as it eliminates sample-to-sample uncertainties in the physical properties studied. A three terminal device having a pair of detector electrodes placed symmetrically about the injection point is used to directly demonstrate decoupling of spin and charge current in nanostructures. Furthermore, by varying the thickness of the normal metal channel on the scale of the mean free path the surface contribution to spin relaxation is measured and compared to the bulk spin scattering rate. It is found that for Al surface scattering makes a weak contribution to the overall spin relaxation rate, the result that should be important for a number of proposed thin film spin-based devices. The interplay between non-equilibrium magnetism and superconductivity is studied in a ferromagnetic/superconductor single electron transistor. Spin imbalance in the base is controlled by the bias voltage applied to the magnetic emitter/collector as well as the relative orientation of their magnetic moments. A strong magneto-transport effect is observed and attributed to a suppression of the superconducting gap in the center electrode by the spin imbalance in the antiparallel state of the device. The intrinsic spin relaxation parameters for the center electrode, important for interpreting the data are studied in a separate experiment using spin injection into a one-dimensional superconducting channel. It is found that the spin accumulation increases substantially on transition into the superconducting state while the spin diffusion length is reduced. These results represent a new way of combining magnetism and superconductivity on the nano-scale. / QC 20100924

No description available.

Underground fixed guideway system has become an important solution to alleviate over-crowded population problems , especially in urban areas. During the planning stage, the station and the underground tunnel formed an enclosure which necessitated environmental control in order to facilitate thermal comfort and safety in case of fire. In this study, SES program has been utilized as a tool in evaluating the performance of the tunnel ventilation system under normal, congestion , and emergency operation modes, using an actual railway underground project as an example. Conclusions has been drawn that safety criteria can be met successfully, following the SES simulation results with recommendations made to facilitate successful ventilation modes.

For the purpose to understand the diversity, distribution and abundance of faunas, and to determine the variables that would influence the faunal diversity in caves and tunnels, observations and records had been made during September 1999 to June 2000 in Kenting area, the southern tip of Taiwan. A total number of 19 caves and 2 tunnels were studied. Among them, 4 caves are located in the forest recreation area, 15 caves in the natural preserved area, 1 tunnel in Guanshan village and another tunnel in Mt. Dayuan area. All the faunal species included 3 species of Malacostraca, 2 species of Arachnida, 2 species of Chilopoda, 3 species of Insecta, 3 species of Amphibia, 3 species of Reptilia and 7 species of Mammalia. Among these fauna species, the crickets (Ceuthophilus maculatus), the spiders (Heteropoda venatoria) and the ants (Polyrhachis sp.) had a widely distribution and are the most common species in caves and tunnels. Among all the continuous structural variables of caves and tunnels, the entrance height (r=-0.47) and the entrance area (r=-0.48) had a negative correlation with Shannon-Wiener¡¦s diversity (p<0.05). On the other hand, the total length (r=0.48) and the length of dark zone (r=0.52) had a positive correlation with diversity (p<0.05). In addition, the height of the dark zone had a negative correlation (r=-0.53, p<0.05) with evenness. Among the categorical descriptive variables, human disturbance and multiple chambers had a significant difference with Shannon-Wiener¡¦s diversity (P<0.05). The caves or tunnels visited by people from 2 to 4 times per month had the highest values of diversity, and the caves or tunnels visited by people more than 4 times per month had the lowest values of diversity. In addition, the values of diversity in caves and tunnels with multiple chambers were higher than the ones in caves and tunnels without multiple chambers.

ABSTRACT This study is aimed to investigate the transport of air pollutants and traffic flow in Chungcheng and Cross-Harbor Tunnels in Kaohsiung City. The work includes road measurements and three-dimensional numerical modeling. This article reports the first part of the work concerning measurement results. The items on road-side investigation include traffic flow rate traffic, speed, travel time and vehicle catergory. The air pollutants being sampled and analyzed in the tunnels are carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOX) and total hydrocarbon (THC). The road-side investigations show that the major vehicles in Chungcheng Tunnel are passenger cars, the next are small trucks, and the minor are large trucks. The peak hours are at 10:30 ¡V 11:30 in the morning and 15:30 ¡V 17:30 at afternoon with average traffic flow rate in 250 ¡V 350 No./hr. The major vehicles in Cross-Harbor Tunnel are motorcycles, the next are passenger cars, large trucks and small trucks. Traffic flow rate at morning peak hours of 7:00 ¡V 8:00 are 1,800 and 1,000 No./hr for motorcycles and passenger cars, respectively, and are below 800 No./hr for the large and small trucks. Results of air pollutants analysis show that CO in Cross-Harbor Tunnel is about as three times as that of Chungcheng Tunnel due to high motorcycle flow rate in Cross-Harbor Tunnel. The maximum concentration of NOX was about 500 ppb for Cross-Harbor Tunnel and was about 1,000 ppb for Chungcheng Tunnel during the study period, suggesting that cars and trucks are the major emission sources of NOX. The transport of air flow and gaseous pollutants downstream (or to the tunnel exit) is mainly done by tunnel fans and piston effect of moving vehicles in order to decrease pollutants concentrations inside the tunnel. The mechanism is affected by fan number and flow rate, traffic flow rate, traffic speed and net tunnel aspect ratio. Results in two tunnels show that CO and NOX both increase with increasing downstream distance, but are not always so for SO2 and THC. Whether other mechanisms such as absorption of SO2 and THC on tunnel walls or sink and absorption on tunnel floor due to being heavier than air affect distributions of SO2 and THC remains further investigations.

No description available.

Univ., Diss.--Hannover, 2005. / Literaturverz. S. 296-317.

Thèse de doctorat : Physique : Nancy 1 : 2007. / Titre provenant de l'écran-titre. Bibliogr.