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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.
1

UHV studies of the adsorption of small adsorbate molecules on low index platinum single crystals

Baily, Christopher John January 2003 (has links)
No description available.
2

Multiscale Structure-Property Relationships of Ultra-High Performance Concrete

Burcham, Megan Noel 12 August 2016 (has links)
The structure-property relationships of Ultra-High Performance Concrete (UHPC) were quantified using imaging techniques to characterize the multiscale hierarchical heterogeneities and the mechanical properties. Through image analysis the average size, percent area, nearest neighbor distance, and relative number density of each inclusion type was determined and then used to create Representative Volume Element (RVE) cubes for use in Finite Element (FE) analysis. Three different size scale RVEs at the mesoscale were found to best represent the material: the largest length scale (35 mm side length) included steel fibers, the middle length scale (0.54 mm side length) included large voids and silica sand grains, and the smallest length scale (0.04 mm side length) included small voids and unhydrated cement grains. By using three length scales of mesoscale FE modeling, the bridge of information to the macroscale cementitious material model is more physically based.
3

Alloy effects in catalysis : the structure and reactivity of the CuPd[85:15]{110}p(2x1) surface

Newton, Mark A. January 1993 (has links)
No description available.
4

A search for UHE gamma-ray emission from known celestial objects using EAS muon content selection

Luxton, Stephen John January 1994 (has links)
No description available.
5

Application of the ultra high resolution, low voltage scanning electron microscopy in the materials science

Kawano, Kayoko January 2012 (has links)
The efficiency of low voltage scanning electron microscopy, which presents near-surface information, has been well known for a long time. However, it is not widely known that the high resolution capability can only be achieved when the surface reveals the original characteristics of the materials without any deterioration due contamination. Therefore, initial attention in this study is directed at clarifying the efficient use of the ultra high resolution, low voltage SEM (UHRLV SEM), (Ultra55, Zeiss). The SEM images and the selected electrons for detection, and damage that occurs through UHRVL SEM observation are also researched. Subsequently, the most efficient specimen preparation technique, which is appropriate for the characteristics of the individual materials, is investigated for galvanized steel, ultrasonically welded alloys of Al6111 and AZ31 alloy, Ti6Al4V alloy honeycomb structure and a ceramic sensor. The outcomes of appropriate specimen preparation technique and use of the extremely Low-Voltage below 2.0 kV, are presented in the results section. The study also presented the challenge of improving the low compositional contrast for the dissimilar materials of aluminium and magnesium, and to reduce charging effects in an insulating material comprising a ceramic sensor. As an application of the surface prepared by the process in this study, 3D tomography is also introduced.
6

Effect of Aging on the Quality of Beef Semitendinosus Muscle Treated with Ultra High Temperature Pasteurization

Nur, Habiba Ali 01 May 1998 (has links)
The objective of this study was to determine the effect of aging on the tenderness and palatability of beef from the semitendinosus muscle of the round. Tenderness may be affected by the length of the aging period and the aging temperature. Steaks from the semitendinosus muscle were stored for 0, 3, 6, 9, 12, and 24 hr at two temperatures, 43.3°C and 2.2°C. Ultra high temperature (UHT) pasteurization was accomplished by subjecting the meat to 1100°C for 20 seconds. UHT pasteurization denatures surface proteins, destroys vegetative pathogens, and eliminates some spoilage organisms from the surface of the meat. UHT -treated steaks were cooked in a microwave oven to an internal temperature of 71.1°C. Two cores were taken from the center of each cooked steak. Shear values (lb) were determined on the cores using a Warner Bratzler shear. The results of the study showed that the UHT-treated steaks that were stored at 43.3°C were significantly more tender than those that were refrigerated at 2.2°C regardless of the length of the aging period up to 24 hr. Additional tenderness at 2.2°C when the aging period exceeds 24 hr may be possible. Total plate count (TPC) of raw and UHT-treated steaks was determined using the standard plate count method. The average TPC for the raw steaks was significantly higher than the UHT-treated steaks. The TPC was not significantly different between the UHT- treated steaks that were aged and those that were not aged. A trained panel was used for sensory evaluation to evaluate the moistness, tenderness, and flavor of the steaks using a 9-point hedonic scale. Sensory scores of the UHT-treated steaks revealed that steaks stored at 43.3°C had significantly more moisture and were more tender than those stored at 2.2°C. The panel noted more spoiled flavor among the steaks stored at 43.3°C than 2.2°C. Steaks stored at 2.2°C received significantly higher flavor scores than those stored at 43.3°C.
7

Besign-directed measurements of B1 heterogeneity and spin-lattice relaxation for 8 Tesla MRI

Mitchell, Chad A. 12 October 2004 (has links)
No description available.
8

UHT processing and aseptic filling of dairy foods

Scott, David L. January 1900 (has links)
Master of Science / Food Science Institute / Karen A. Schmidt / The demand for ultra high temperature processed and aseptically packaged dairy foods is growing throughout the U.S. The technology provides value-added food preservation for many foods including flavored milks, puddings, custards, creams, ice-cream mixes, whey-based drinks, sports drinks, and yogurt. Ultra high temperature nonfat milk, milk, light cream, and 18% cream are used throughout the U.S. by the restaurant and food service industries. There are several advantages to aseptic processing and packaging over traditional pasteurization. Advantages include extended shelf life, lower energy costs, and the elimination of required refrigeration during storage and distribution. Challenges are present in all aspects of dairy processing. Major challenges associated with ultra high temperature processing and aseptic packaging of dairy foods include product quality loss, such as age gelation, fat separation, and flavor loss, as well as manufacturing issues such as limited production capacity, potential contamination, slow packaging speeds, and limited shelf life knowledge. This report reviews the history of aseptic processing, principles of ultra high temperature processing, principles of aseptic filling, quality control of UHT dairy foods, and regulations for dairy processors.
9

A search for ultra-high energy neutrinos with AMANDA-II

Wiedemann, Christin January 2007 (has links)
High-energy neutrinos are capable of carrying information over vast distances, and neutrino telescopes such as AMANDA-II provide the means to probe deep inside the violent and energetic interior of the universe. AMANDA-II is located in the glacial ice at South Pole in Antarctica and is optimised to detect Cherenkov emission from neutrino-induced muon tracks with energies above 100 GeV. Data acquired in 2003 with the AMANDA-II detector were searched for a non-localised flux of neutrinos with energies in excess of 1 PeV. Because of the energy dependence of the neutrino mean free path, the Earth is essentially opaque to neutrinos above PeV energies. Combined with the limited overburden of the AMANDA-II detector (about 1.5 km), this means that a potential ultra-high energy neutrino signal will be concentrated at the horizon. The background for the analysis consists of large bundles of muons produced in atmospheric air showers. Owing to their energy losses, muons cannot penetrate the Earth, and the background will be downwards moving. After applying different selection criteria, one event was observed in the final data sample, while 0.16±0.04 background events are expected. The corresponding 90% confidence level upper limit is 4.3. The expected number of neutrino signal events for a 10-6 E-2 GeV/(s sr cm2 ) flux assuming a Φ(νe) : Φ(νμ) : Φ(ντ) = 1:1:1 flavour ratio is 4.1±0.2, yielding an upper limit on the all-flavour neutrino flux of E2 Φ90 ≤ 1.1∙10-6 GeV/(s sr cm2 ), including systematics and with the central 90% of the signal found in the energy range 480 TeV - 1.6 EeV.
10

Investigating Brain Networks Associated with Insight in Adolescents at Ultra High-Risk for Schizophrenia

Clark, Sarah 03 May 2017 (has links)
Background. Impaired insight, or unawareness of illness, is a common symptom of schizophrenia. Clinical insight is awareness of having a mental disorder; cognitive insight is ability to self-reflect (self­reflectiveness) and certainty in cognitions (self­certainty). In schizophrenia insight is associated with brain function and improving insight is a potential early intervention point. This study investigated whether insight is impaired in youth at ultra high-risk (UHR) for psychosis, and if it is related to major brain networks. Methods. Data from a larger UHR study was used, including 55 UHR adolescents and 55 controls assessed with the Structured Interview of Prodromal Symptoms, MATRICS Consensus Cognitive Battery, Scale to Assess Unawareness of Mental Disorder, and Beck Cognitive Insight Scale, as well as resting state functional MRI scans. UHR and control groups were tested for differences in self-reflectiveness and self-certainty, and correlations between insight dimensions and clinical and cognitive measures. Functional connectivity was calculated for the default mode, the cingulo-opercular, and central executive networks and regressed on participants’ reported clinical and cognitive insight, while covarying for head motion. Results. Self-reflectiveness was higher in the UHR group (d = 1.28), but the groups did not differ in self-certainty (d = 0.28). Among UHR, poorer clinical insight was related to greater symptom severity. Default mode connectivity was negatively correlated with self-reflectiveness (R2 = .091) and clinical insight (R2 = .399) in UHR, but no such correlations were found in controls. Cerebello-prefrontal cortex connectivity was negatively associated with self-certainty in the UHR group (R2 = .089 - .138). Conclusions. Default mode connectivity appears to be associated with the facets of insight concerning self-awareness, whereas cerebello-prefrontal connectivity appears to be associated specifically with self-certainty. This is the first study to relate major brain networks to insight before the onset of psychosis, and is consistent with models proposing that different facets of insight are related to self-awareness and executive functioning through networks associated with these processes.

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