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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.
191

Performance improvement of MEMS accelerometers in vibration based diagnosis

Badri, Abdellatef E. O. January 2011 (has links)
Vibration measurement and analysis has been an accepted method since decades to meet a number of objectives - machinery condition monitoring, dynamic qualification of any designed structural components, prediction of faults and structural aging-related problems, and several other structural dynamics studies and diagnosis. However, the requirement of the vibration measurement at number of locations in structures, machines and/or equipments makes the vibration measurement exorbitant if conventional piezoelectric accelerometers are used. Hence, there is a need for cheaper and reliable alternative for the conventional accelerometers. The Micro-Electro-Mechanical Systems (MEMS) accelerometers are one such cheap alternative. However, a significant deviation in the performance of the MEMS accelerometers has been observed in earlier research studies and also confirmed by this presented study when compared with well known conventional accelerometer. Therefore, two methods have been suggested to improve the performance of the existing MEMS accelerometers; one for correction in time domain and other in frequency domain. Both methods are based on the generation of a characteristic function (CF) for the MEMS accelerometer using well known reference accelerometer in laboratory tests. The procedures of both methods have been discussed and validations of these methods have been presented through experimental examples. In addition, a Finite Element (FE) model of a typical MEMS accelerometer has been developed and modal analysis has been carried out to understand the dynamics of capacitive type MEMS accelerometer and to identify the source of errors. It has been observed that the moving fingers behave like a cantilever beam while the fixed fingers showed rigid body motion. This cantilever type of motion seems to be causing non-parallel plates effect in the formed capacitors between moving and fixed fingers which results in errors in the vibration measurement. Hence, design modifications on finger shape have been suggested to remove the cantilever motion and results showed remarkable improvement. Moreover, the effect of using synchronous amplitude modulation and demodulation in the readout circuit has been studied. The experimental study showed that this circuit also introduces errors in amplitude and phase of the output signal compared with the input signal. Thus, in the new design of MEMS accelerometers, improvements in both mechanical design and electronic circuit are required.
192

Meromorphic extensions of dynamical generating functions and applications to Schottky groups

Mcmonagle, Aoife January 2013 (has links)
This thesis is concerned with finding meromorphic extensions to a half-plane containing zero for certain generating functions. In particular, we generalise a result due to Morita and use it to show that the zeta function associated to the geodesic flow over a quotient of a Schottky group can be meromorphically extended to a half-plane containing zero. Moreover, we show that the special value at zero can be calculated. These results are then generalised to obtain meromorphic extensions past zero for L-functions defined on quotients of Schottky groups and to provide an expression for the special value at zero. Finally we show that Morita's method can be adapted to provide a meromorphic extension to a half-plane containing zero for Poincaré series defined for a Schottky group, and that in special circumstances the value at zero can be calculated.
193

Obesity and Pulmonary Function in Navajo and Hopi Children

Eisenmann, Joey C., Arnall, David A., Kanuho, Verdell, Interpretter, Christina, Coast, J. Richard 01 December 2007 (has links)
Background: Although several reports have shown an adverse cardiovascular and metabolic risk profile associated with childhood obesity, few reports have examined the effects of childhood obesity on pulmonary function. Objective: The purpose of this study was to examine the influence of obesity on pulmonary function in Navajo and Hopi children. Methods: Subjects included 256 (110 males, 16 females) Hopi children 6-12 years of age and 557 (274 males, 283 females) Navajo children 6-12 years of age (N=813). The body mass index was used to classify subjects as normal weight, overweight, or obese on the basis of international reference values. Forced vital capacity (FVC), forced expired volume in one second (FEVl), FEV1% (FEV1 to FVC ratio; FEV1/FVC), and forced expiratory flow between 25%-75% of vital capacity (FEF25-75) were determined according to the American Thoracic Society recommendations. Results: Approximately 26% of Navajo and Hopi children were defined as overweight (26.0% of boys and 25.6% of girls) and an additional 16% (14.6% of boys and 17.7% of girls) were defined as obese. In general, the patterns showed an increase in pulmonary function between normal weight and over-weight children and a decrease in pulmonary function of obese children. Significant differences among groups existed for FEV1% and FEF25-75 in boys and FVC and FEV1 in girls. Conclusions: The results indicate the pulmonary consequences of obesity in children and provide further evidence of the adverse consequences, of pediatric obesity among Native Americans.
194

Diet Quality and Differences in Physical and Cognitive Function of U.S. Older Adults

Jung, Jessica Yuri January 2020 (has links)
No description available.
195

The impact of local heat therapy on vascular function in young, healthy, recreationally active adults

Cheng, Jem L 15 June 2023 (has links)
Heat therapy may be an alternative or adjunct intervention to exercise training for improving cardiovascular function and health. However, its prescription must be refined in order to overcome the feasibility and tolerability issues associated with current whole-body heating modes. There is substantial evidence to support the beneficial effects of high doses (e.g., frequency, duration, and intensity) of heating typically achieved using whole-body modes, but there is limited knowledge on whether lower doses of heating administered through local hot water immersion of the limbs can still have an impact on vascular function. All studies were conducted in heathy young men and women. In the first study, we found that regardless of whether local heating was applied to the lower limbs up to the ankles or knees, upper limb endothelial function and lower limb arterial stiffness improved acutely. In the second study, we proceeded to prescribe ankle-level heating in a chronic intervention and compared its effects to that of moderate-intensity cycling exercise training. We observed no changes in endothelial function, but decreases in central arterial stiffness and increases in cardiorespiratory fitness in those who performed heat therapy and exercise training combined with heat therapy. In the third study, we evaluated the ability of acute vascular function responses to predict chronic vascular function responses with heating and exercise interventions, and found significant positive associations between the acute and chronic responses for absolute and relative brachial artery flow-mediated dilation and femoral-foot pulse wave velocity. These findings suggest that, in healthy young men and women, local heating through ankle-level hot water immersion can improve indices of cardiovascular function both acutely and chronically, alone or combined with exercise training. Further, acute responses may be used to determine an individual’s chronic responsiveness to a heat therapy and/or exercise training intervention. More research in larger, more diverse samples and with a longer duration of therapy and/or training should be conducted to determine if the results are replicable. / Dissertation / Doctor of Philosophy (PhD) / Regular participation in whole-body heat therapy can extend health and life span, but it is used infrequently because of a lack of feasibility from a cost, accessibility, and tolerability standpoint. This thesis explored whether local heat therapy in young healthy men and women would be effective for improving blood vessel health defined as endothelial function and arterial stiffness, both of which are linked to the risk of developing many chronic diseases. Furthermore, the effects of local heat therapy were compared to that of exercise training. We found that there were beneficial short- and long-term effects of lower limb hot water immersion that manifested in different areas of the body. Local heat therapy improved upper limb endothelial function and lower limb arterial stiffness immediately after a session, whereas with repeated exposure, it may have improved central arterial stiffness and cardiorespiratory fitness. Exercise training only had beneficial effects on the blood vessels when combined with heat therapy. Finally, short-term vascular responses can predict long-term vascular responses to both heat therapy and/or exercise training. Overall, our findings suggest that there may be some utility for local heat therapy to promote healthy blood vessels, but more work must be done to replicate our findings and explore its effects on other populations.
196

A structured approach for function based decomposition of complex multi-disciplinary systems

Campean, Felician, Henshall, Edwin, Yildirim, Unal, Uddin, Amad, Williams, Huw January 2013 (has links)
No / The aim of this paper is to introduce the Systems State Flow Diagram as a structured approach to high level solution-independent function based decomposition of a complex multi-disciplinary system. The approach is discussed in the context of existing function modelling frameworks and in relation to current practice in industry. A generic case study is used to introduce the approach and to highlight the salient features, followed by an illustration on its application to the analysis of an electric vehicle powertrain. Experience with the practical application of the approach with engineering teams is discussed.
197

Metric Preserving Functions

Lazaj, Klotilda 30 October 2009 (has links)
No description available.
198

The Impact of Exercise on Mood, Social and Cognitive Outcomes

Keating, Laura January 2018 (has links)
While the physical health benefits of exercise are well established, mental health benefits remain unclear. The literature reports reduced stress and improved cognitive function in rodent exercise studies, and improved mood scores in humans. However, though mood disorders are characterized by poor response to treatment, studies rarely evaluate difficult-to-treat patients or functional outcomes. Therefore, we evaluated the impact of 12-week, group-based exercise programs (running or yoga) on mood and functional outcomes including health-related quality of life (HRQOL) and social and cognitive functioning. Methods: Study 1 was a retrospective review of mood and stress outcomes in participants with difficult-to-treat mood disorders. In Study 2, we measured functional outcomes before and after the running program in a subsample from Study 1. Improved friendship and high injury rates in the running group inspired Study 3, a randomized control trial to evaluate mood and functional outcomes in a non-clinical sample using yoga, a low-impact exercise program that included cognitive control. Results: In Study 1 (n=46), depression (p<0.0001) and stress (p=0.01) scores improved over time, and improved friendship levels were predictive of improved mood scores (p<0.04). In Study 2 (n=18), we found improved scores on several HRQOL subscales, including social functioning (p-values<0.01) and weak improvements in working memory and processing speed (p-values<0.04). In Study 3, yoga participants (n=20) had improved stress (p=0.02), loneliness (p=0.002), and HRQOL (p-values<0.03) scores, compared to wait-list controls (n=8). Yoga participants improved on tasks reflecting hippocampal memory (p-values<0.006) and attention and inhibitory control (p=0.03). Regression and mediation analyses suggest that social support mediates the stress-reducing impact of yoga (p-values<0.0005). Discussion: Group-based exercise programs impart benefits across mental health and functional outcomes for participants with and without mood disorders. Exercise may be an effective adjunctive treatment for mood disorders, and more data is needed on how social support impacts clinical outcomes. / Thesis / Doctor of Philosophy (PhD) / This dissertation examines the impact of exercise across multiple indications of mental health and functioning including mood scores, stress, cognitive function, social function and health-related quality of life (HRQOL) in participants with and without mood disorders. Youth and adults engaged in 12-week group-based exercise interventions of running or yoga and completed comprehensive mental health and neurocognitive assessments. Results: Participation in a structured exercise program was associated with improved stress and depression, social functioning, physical and mental HRQOL domains and limited improvements in cognitive function. Results also support therapeutic benefits of structured high- and low-intensity exercise programs across multiple symptoms in patients with difficult-to-treat mood disorders, and further suggest that reduced stress and increased social functioning play key roles in the mental health benefits observed. These results represent a new standard for mood disorders research, to better understand the how lifestyle strategies are effective for the treatment of mental illness.
199

Limit Cycle PIO Analysis With Simultaneously Acting Multiple Asymmetric Saturation

Lamendola, Joel E. 12 June 1998 (has links)
Pilot in-the-loop oscillation (PIO) is a phenomenon which occurs due to the dynamic interaction between pilot and aircraft. This detrimental aircraft handling quality appears through a variety of flight conditions and is very difficult to predict. Due to this complex behavior, PIO is not easily eliminated. This report describes a method of PIO analysis that is capable of examining multiple asymmetric nonlinearities acting simultaneously. PIO analyses are performed on a model based on the USAF NT-33A variable stability aircraft with nonlinearities including stick position limiting, elevator deflection limiting, and elevator rate limiting. These analyses involve the use of dual input describing functions which enable the prediction of frequency, amplitude, and mean point of oscillation. / Master of Science
200

The development of a large interval recombinase mediated cassette exchange (RMCE) strategy

Penfold, Catherine January 2005 (has links)
Murine embryonic stem (ES) cells have provided researchers with a useful tool to investigate genome function and the consequences of genome mutation. One mutational approach is gene-targeting, this involves the introduction of DNA sequences of choice, precisely, to almost any location in the target genome by homologous recombination. At present, most gene-targeting strategies introduce DNA constructs that derive from plasmids. Plasmids can stably propagate up to approximately 30 kb of DNA. Therefore, this size limit may place a restriction on the range of mutations that may be made to a genome using a single plasmid-derived gene-targeting construct alone. To overcome this limitation, multiple rounds of sequential gene-targeting experiments may be performed, however such an approach may be too lengthy to be practicable. In order to address this current limitation with gene-targeting a novel strategy was tested, implementing Cre-lox site-specific recombination (SSR) technology and the bacterial artificial chromosome (BAC) vector system. Two sequential gene-targeting events in murine E14Tg2a ES cells (HPRT) were performed at separate locations to chromosome 11. The aim of gene-targeting was to create an interval on chromosome 11 that included a single copy of the murine alpha-globin locus, between the hetero-specific lox sites, loxP and lox511, an interval of approximately 64 kb. To this end the first targeting event delivered lox511 /hygromycin/I See Illox51 J sequences and the second event frt/I See I/5'hprt//oxP/neomycin sequences. ES cells that were confirmed to have correctly undergone the two desired targeting events (double-targeted) were then assessed to determine whether these events had occurred to the same chromosome 11 (in eis ), as desired, or to the alternate copies of chromosome 11 (in trans). This assessment involved restricting DNA from the double-targeted ES cell lines with the rare-cutting restriction endonuclease I See I and resolving the products of this restriction by pulsed field gel electrophoresis. This analysis identified two in cis lines (CAT-A3 and CAT-B3) and an in trans line (CATCIO). The double-targeted ES cell lines were then further characterised to determine whether the hetero-specific lox sites they harboured would participate in ere-mediated SSR. The positive result of this analysis was the generation of ES cell clones that were hemizygous for the alpha-globin locus, a deletion of 64 kb. Hemizygous ES cell clones were obtained from the CAT-A3 and CAT-B3 ES cell lines, as predicted, but not from the CAT-C 10 line, although all the lines tested showed evidence of SSR occurring. In parallel to achieving the interval between loxP and lox51 l in ES cells, a BAC, harbouring the alpha-globin locus, was similarly modified with lox sites using recombination-mediated cloning. The aim of the BAC modification was to create an interval between lox sites in the BAC identical to that achieved in the ES cells. The BAC was targeted sequentially with two separate constructs, lox511/k.anamycin/lox511/HSVtk and then blasticidin/loxP/3'hprt/I See 11.frt. The correct targeting of the BAC was verified by restricting its DNA with a panel restriction endonucleases. The lox sites were then tested in an in vitro analysis with purified Cre recombinase and found to be competent to participate in SSR reactions. The modified BAC was co-electroporated with a Cre expression plasmid into the CAT-A3 and CAT-B3 ES cell lines, previously characterised as targeted in eis, with the aim of exchanging the interval sequences in the ES cell with those of the BAC. The ultimate aim of such an exchange would be to deliver any combination of mutations that would be previously engineered to the BAC interval, to that of the ES cell, by a single SSR event. This experimental approach should expedite and facilitate the mutational analysis of gene loci. To generate comparative data the result of SSR between the modified BAC and an in trans targeted ES cell line (CAT-CI 0) was also assessed. The selection for the desired exchange involved reconstruction of an Hprt minigene and exclusion of a thymidine kinase gene, cells which haboured these events could therefore be selected for in HAT and ganciclovir supplemented media respectively. ES cell clones generated from both of the in cis lines tested (CAT-A3 and CAT-B3) had the correct selection resistance profiles, thus indicating that the desired exchange had been achieved in these clones. Additionally, Southern blot analysis from the DNA from these clones was consistent with the achievement of the desired exchange. However, the results obtained from clones generated from the in trans line (CAT-CI 0) were not consistent with their predicted genetic arrangement following SSR with the modified BAC. Thus far similar experimental approaches have been implemented to exchange smaller intervals of I to 5 kb and have been termed recombinase mediated cassette exchange (RMCE). However the experiments described within this thesis are the first test whether the same rationale may be applied to larger intervals. The strategy described and tested in this thesis has therefore been termed large interval RMCE (liRMCE).

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