• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 527
  • 446
  • 103
  • 86
  • 72
  • 36
  • 14
  • 10
  • 7
  • 7
  • 6
  • 6
  • 5
  • 2
  • 2
  • Tagged with
  • 1561
  • 201
  • 199
  • 123
  • 122
  • 109
  • 108
  • 92
  • 91
  • 84
  • 75
  • 72
  • 69
  • 67
  • 64
  • 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.
451

Exploring the application of the green movement to the theatre with a focus on the costume shop

Maynard, Natalie Lynn 13 July 2011 (has links)
Theatre is an art form that combines the art of storytelling with the visual arts. Every production begins with a blank canvas, and it is up to the director and a team of designers to discuss concepts and decide on an artistic vision for the piece. Skilled artisans work quickly as a team to produce the vision of the designer and director. During the production process waste is generated in the scene shop, props shop, costume shop, and rehearsal space. The products that are used to create the design can often contain harmful ingredients for both the artisan and the environment. No longer willing to ignore the responsibility that theatres have as stewards to the environment many artisans are leading the way by exploring safer practices and products. The research for this thesis is focused on the theatrical costume shop and examines dry cleaning, fabric painting and dyeing, and waste disposal. Alternatives to regular dry cleaning practices and commonly used and otherwise toxic products are available for a variety of processes we use in the theatre. For this study I conducted one hundred and sixty five surveys, ten interviews and a quality test amongst the dry cleaning alternatives in Austin, Texas. Three sets of seven different fabric samples were cleaned using the standard solvent and the alternative methods for dry cleaning. Four professional dyers and painters were interviewed about their dyeing process, disposal practices, and the impact that “green” products have on their work. I spoke with two experts working in wastewater about the impact dyes and paints have on wastewater treatment plants. Finally, I conducted an anonymous survey in 2010 to find out what new products or methods are in use amongst costume shop managers, dyers and painters, and production managers. / text
452

Climate variability over the American monsoon and Amazonian regions during the last decades

Arias-Gómez, Paola Andrea, 1979- 24 October 2011 (has links)
This dissertation aims to identify the main changes in monsoon activity observed over the American monsoon and Amazonian regions during the last decades and the possible links between such changes. To address this, several observational and reanalysis datasets were used. The results suggest the occurrence of two regime types of the North American monsoon during 1948-2009: two dry regimes during 1948-1959 and 1990-2009 and one wet regime during 1960-1989. The occurrence of such regimes is modulated by the Atlantic Multidecadal Oscillation. However, the two dry regimes have different causes. In particular, the more recent dry regime is mainly due to both an anomalous westward expansion of the North Atlantic Subtropical High and a northward displacement of the subtropical jet stream over the United States. The former enhances the low-level flow from the Gulf of Mexico to the Great Plains and weakens moisture transport to Mexico and the southwestern US. In addition to such a weakening of the North American monsoon during the last two decades, this research shows that the American monsoon systems have shortened after 1978 due to a trend toward earlier retreats of the North American monsoon and delayed onsets of the southern Amazon wet season. These changes produce a longer transition season between both monsoon systems. Whether these changes are caused by a common factor or they are the consequence of independent and unrelated causes was not clear previously. The results discussed here indicate that the observed changes in the American monsoons are partially a consequence of the westward expansion of the North Atlantic surface high observed since 1978. Such a westward expansion enhances the activity of easterly waves over the southern Caribbean Sea and northern South America, producing a dominant easterly flow over the region, which in turn prevents the reversal of the cross-equatorial flow necessary to transport moisture to the southern Amazon and the South American monsoon domain and contributes to its delayed onset. This investigation provides evidence that the shortening and weakening of the American monsoons and the lengthening of the transition season between them are associated with the same large-scale forcing, which may be caused by anthropogenic influence. / text
453

Food quality and properties of quality protein maize.

Leal Diaz, Ana Maria 30 September 2004 (has links)
Quality protein maize (QPM), high protein corn (HPC) and food grade maize (FGM) were processed into tortillas and direct expanded extruded snacks. QPM had similar test weight, density and kernel size with 45% more lysine and 38% more tryptophan compared to FGM. HPC had the largest kernel with density and test weight similar to FGM. During alkaline cooking, HPC absorbed water faster than QPM and FGM. White QPM required shorter cooking time and had less dry matter losses compared to FGM. All corn varieties had excellent pericarp removal at the optimum cooking time. Tortillas from QPM had better pliability and rollability after storage compared to FGM and HPC. HPC tortillas had lower rupture force after storage. The use of QPM for tortilla production may reduce energy and sewage cost, and could produce a tortilla with longer shelf stability with improved nutritional value. Decorticated and non-decorticated QPM, FGM and HPC grain were processed into corn meal and direct expanded snacks. A modified short scale dry milling system was used to produce the corn meal. QPM produced more coarse meal with greater fat content compared to FGM. Decortication decreased fiber content and coarse meal yield. Non-decorticated meal had greater protein, fiber and fat content compared to decorticated meal. The modified short flow milling system provides reduced lost fractions for extrusion into nutritionally improved products. Extrusion was performed in a low cost friction extruder. QPM extruded faster than FGM and HPC. FGM required greater specific mechanical energy than QPM. Extrudates from FGM were the most expanded followed by QPM and HPC. Extrudates from the three corn varieties were acceptable to the panelists and decortication did not affect acceptability. The improved nutritional value of QPM, was retained during dry milling and extrusion. Current QPM varieties can be processed into tortillas with longer shelf stability and meal for extrusion into a wide variety of snacks and other foods. These may have application in specialty health foods and in developing countries where maize is a staple food.
454

Relationships between Maritime Container Terminals and Dry Ports and their impact on Inter-port competition

Castrillon, Robert January 2012 (has links)
Globalization of the world’s economy, containerization, intermodalism and specialization have reshaped transport systems and the industries that are considered crucial for the international distribution of goods such as the port industry. Simultaneously, economies of location, economies of scope, economies of scale, optimization of production factors, and clustering of industries have triggered port regionalization and inland integration of port services especially those provided by container terminals. In this integration dry ports have emerged as a vital intermodal platform for the effective and efficient distribution of containerized cargo. Dry ports have enabled port and hinterland expansion increasing the competitiveness of container terminals at seaports. In consequence, container terminals and dry ports are establishing formal and informal relationships to strengthen the competitiveness of their hinterlands and to improve their role in the physical distribution of goods. This study assesses the characteristics of relationships between container terminals and dry ports. Such assessment is conducted based on a set of relationship characteristics proposed in a relationship assessment model for customer/supplier, in which dry ports are given the role of suppliers of port services to container terminals. In addition, the research assesses the impact of the relationships between container terminals and dry ports on inter-port competition. The main findings of the research led to conclude relationships between container terminals and dry ports are characterized by medium mutuality, low particularity, low co-operation, low conflict, low intensity, low interpersonal inconsistency, high power/dependence and medium trust. Additionally, it was concluded that such relationship characteristics impact inter-port competition in two main ways. In one hand by driving container terminals to maximize the utilization of dry port’s capabilities such as container transport/delivery, container storage, customs clearance, information systems and intermodal connections to industrial clusters. On the other hand, by constructing channels of interaction through which dry port’s benefits for hinterlands such as increase of container terminal capacity, reduction of road congestion, increase of modal shift and hinterland expansion are used as leverage in competition for containerized cargo.
455

Energy efficient storage of biomass at Vattenfall heat and power plant

Eriksson, Anders January 2011 (has links)
Storage of biomass is often associated with problems such as heat development, drymatter losses and reduction of fuel quality. The rise in temperature can potentiallycause a risk of self-ignition in the fuel storage. Moreover, emissions from storage pilescan cause health problems in the surrounding. The dry matter losses and reduction offuel quality can have economical effects. The aim of this thesis project is to developguidelines on how to store large amount of biomass at Vattenfalls heat and powerplants in an optimal way. Storage trials at Idbäckens CHP were done in order to studythe effect of storage on fuel quality, dry matter losses and temperature development.Two storage trials were performed over six weeks with waste wood chips and stemwood chips stored in about 4.5 m high outdoor piles. A trial over four days in whichwaste wood chips was placed on a heated surface was evaluated. A study to test thepossibility of using waste heat to dry waste wood chips was performed.Small but not negligible dry matter losses were observed in both of the piles of storedmaterial. The largest weekly losses were found during the first week of storage and adeclining behavior could thereafter be seen. The accumulated losses during six weeksof storage were 2.0 % and 1.7 % respectively, for waste wood and stem wood. Storageduring six weeks of waste wood and newly chipped stem wood did not cause anymajor deterioration of the fuel quality as such, beside the substance losses.No drying effect could be seen in the heated surface trial. The surface became warm,about 50°C, but it was not sufficient to dry the chips. The conclusion is that it is notpossible to dry large amount of chips on a heated surface with the design used hereand during four days.The overall conclusion is that in order to minimize the dry matter losses the materialshould be handled according to the LIFO (last in first out) principle. Wheneverpossible, try to purchase fuel that has been stored for a while since the more easilydegraded compounds has already been degraded through microbial activity. There is apossibility that the largest losses has already occurred. Furthermore, try also tocomminute the material (reduce the particle size) at the plant and as close in time tocombustion as possible.
456

MEMS-enabled micro-electro-discharge machining (M³EDM)

Alla Chaitanya, Chakravarty Reddy 11 1900 (has links)
A MEMS-based micro-electro-discharge machining technique that is enabled by the actuation of micromachined planar electrodes defined on the surfaces of the workpiece is developed that eliminates the need of numerical control machines. First, the planar electrodes actuated by hydrodynamic force is developed. The electrode structures are defined by patterning l8-µm-thick copper foil laminated on the stainless steel workpiece through an intermediate photoresist layer and released by sacrificial etching of the resist layer. The planer electrodes are constructed to be single layer structures without particular features underneath. All the patterning and sacrificial etching steps are performed using dry-film photoresists towards achieving high scalability of the machining technique to large-area applications. A DC voltage of 80-140 V is applied between the electrode and the workpiece through a resistance-capacitance circuit that controls the pulse energy and timing of spark discharges. The parasitic capacitance of the electrode structure is used to form a resistance capacitance circuit for the generation of pulsed spark discharge between the electrode and the workpiece. The suspended electrodes are actuated towards the workpiece using the downflow of dielectric machining fluid, initiating and sustaining the machining process. Micromachining of stainless steel is experimentally demonstrated with the machining voltage of 90V and continuous flow of the fluid at the velocity of 3.4-3.9 m/s, providing removal depth of 20 µm. The experimental results of the electrode actuation match well with the theoretical estimations. Second, the planar electrodes are electrostatically actuated towards workpiece for machining. In addition to the single-layer, this effort uses double-layer structures defined on the bottom surface of the electrode to create custom designed patterns on the workpiece material. The suspended electrode is electrostatically actuated towards the wafer based on the pull-in, resulting in a breakdown, or spark discharge. This instantly lowers the gap voltage, releasing the electrode, and the gap value recovers as the capacitor is charged up through the resistor. Sequential pulses are produced through the self-regulated discharging-charging cycle. Micromachining of the stainless-steel wafer is demonstrated using the electrodes with single-layer and double-layer structures. The experimental results of the dynamic built-capacitance and mechanical behavior of the electrode devices are also analyzed.
457

Wave generation and propagation at tribological interfaces

Di Bartolomeo, Mariano, Di Bartolomeo, Mariano 19 December 2011 (has links) (PDF)
This thesis is addressed to the understanding of the mechanisms at the origin of the contact wave fields at frictional interfaces and its relationship with the local characteristics of the surfaces in contact, as well as with the global dynamics and macroscopic frictional behaviour of the system. The aim of this work is to provide insights on the generation and propagation of the waves through the contact both to avoid instabilities and to control their effect on friction. The work is organized in two main parts. The first part presents the development of a non-linear finite element analysis in large transformations of the dynamic rupture at the interface with contact friction separating two bodies (isotropic and elastic) without relative motion. A rupture is considered when an initially sticking zone shifts in sliding state. The properties of the obtained ruptures are analyzed for a flat interface between dissimilar materials in function of the nucleation energy; then the effect of the interface roughness is analyzed. The differentiated rupture inside the asperities and the conditions for coupling and uncoupling between the waves radiating in the two bodies have been also investigated. In the second part, the analysis deals with the sliding onset between two bodies in contact. The sliding between two bodies made of different isotropic elastic materials and separated by a frictional interface is simulated. The evolution along the time of the global normal and tangential forces is analyzed, relating it to the local phenomena occurring at the interface. This part tries to investigate how micro-slips at the interface, acting as distributed ruptures, trigger the macro-slips between the two bodies. The interaction between local and global dynamics is also studied. Finally a numerical parameter space study is carried out, as a function of several system parameters (contact law, friction coefficient, material damping, normal load, translational velocity and regularization time). The results show the key role of the micro-slips and precursors (detectable wave propagations that occur at tangential global force well below the critical value expected by the friction law) in triggering the macro-slip between the two bodies. Depending on their distribution and magnitude the evolution of the contact forces passes from stick-slip-like behaviour to continuous sliding. The local dynamics at the contact (wave and rupture propagation) is linked to the global behaviour of the system (stick-slip, continuous sliding, induced vibrations); the effect of the contact and system parameters on the transfer of vibrational energy between the sliding contact and the system is investigated. The numerical results obtained by the two parts of the work show a good agreement with experimental results in literature.
458

Monitoring year-to-year variability in dry mixed-grass prairie yield using multi-sensor remote sensing

Wehlage, Donald C. Unknown Date
No description available.
459

Antibiotic prophylaxis in third molar surgery.

Siddiqi, Allauddin. January 2007 (has links)
<p><font face="Tahoma"> <p align="left">The purpose of this study is to evaluate the need for prophylactic antibiotic treatment in third molar surgery and to establish specific guidelines for antibiotic prophylaxis in the department of Maxillo-Facial and Oral Surgery (MFOS) at Tygerberg Academic, Groote Schuur and Mitchells Plain Hospitals.</p> </font></p>
460

Mechanism of action and utilization of isothiocyanates from mustard against Escherichia Coli O157:H7

Luciano, Fernando 03 November 2010 (has links)
E. coli O157:H7 has been found to survive in dry sausages and cause disease. Isothiocyanates have been studied for their capacity to eliminate pathogens from foods and are attractive from the consumer perspective because of their natural origin. There is a need to better understand how isothiocyanates kill microorganisms and their behaviour in food matrices. It was found that glutathione and cysteine naturally present in meat can react with AIT, forming a conjugate with no or low bactericidal activity against an E. coli O157:H7. In addition, AIT presented higher anti-E. coli activity at lower pH values; therefore, it should be more efficient in acid foods. AIT was also found to inhibit the activity of thioredoxin reductase and acetate kinase; hence, enzymatic inhibition may represent a way in which AIT kills E. coli O157:H7. Mustard powder is used as a spice (active myrosinase) and/or binder (inactive myrosinase) in meat products. Both of these powders killed E. coli O157:H7 in dry fermented sausage. This was not expected since the powder lacking myrosinase is not able to produce isothiocyanates. Starter cultures and E. coli were found to consume significant amounts of glucosinolates. Pediococcus pentosaceus UM 121P and Staphylococcus carnosus UM 123M (higher myrosinase-like activity) were compared against P. pentosaceus UM 116P + S. carnosus UM 109M for their ability in reducing E. coli viability in dry sausage. Sausage batches containing powders of hot mustard, cold mustard, autoclaved mustard and no powder were prepared. Both pairs of starters yielded similar results. Reduction >5 log CFU/g of E. coli O157:H7 occurred after 31 d for hot powder and 38 d for cold powder; there was no reduction in the control. E. coli O157:H7 itself has greater effect on glucosinolate degradation than either pair of starters, which may be more important in determining its survival. Autoclaved powder caused >5 log CFU/g reduction after 18 d. This may be the result of synergistic/additive interaction among E. coli O157:H7 myrosinase-like activity, the presence of newly formed/released antimicrobials in the autoclaved powder and the multiple hurdles present in the dry sausage. Autoclaved mustard powder has potential as a novel food ingredient for the meat industry.

Page generated in 0.0277 seconds