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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

YXE: beyond boundaries

2014 September 1900 (has links)
In this post-apocalyptic epic set after the collapse of the Digital Age, the region of YXE finds itself at war. Fifteen-year-old Petra seeks to save his pod from the Grunthers, a nomadic tribe of mutineers that have triggered a resurgence of the deadly disease known as rouge. In addition to facing the Grunthers, Petra must also deal with conflicts that have arisen between the settlers from other pods and his own, and the challenges within his own family. After his grandfather’s untimely death, Petra suddenly finds himself the leader of their pod. With the help of his friend Avery, he learns that loyalty comes from actions not mere words, and battles towards survival at all costs. In the meantime, Samuel is also fighting for the survival of his tribe, the Grunthers, while his wife languishes with a fatal case of rouge. There is much at stake as Petra sets forth beyond boundaries to regain his land in YXE. For intermediate-age readers ages 11 and up.
2

Impact of Discretization Techniques on Nonlinear Model Reduction and Analysis of the Structure of the POD Basis

Unger, Benjamin 19 November 2013 (has links)
In this thesis a numerical study of the one dimensional viscous Burgers equation is conducted. The discretization techniques Finite Differences, Finite Element Method and Group Finite Elements are applied and their impact on model reduction techniques, namely Proper Orthogonal Decomposition (POD), Group POD and the Discrete Empirical Interpolation Method (DEIM), is studied. This study is facilitated by examination of several common ODE solvers. Embedded in this process, some results on the structure of the POD basis and an alternative algorithm to compute the POD subspace are presented. Various numerical studies are conducted to compare the different methods and the to study the interaction of the spatial discretization on the ROM through the basis functions. Moreover, the results are used to investigate the impact of Reduced Order Models (ROM) on Optimal Control Problems. To this end, the ROM is embedded in a Trust Region Framework and the convergence results of Arian et al. (2000) is extended to POD-DEIM. Based on the convergence theorem and the results of the numerical studies, the emphasis is on implementation strategies for numerical speedup. / Master of Science
3

A study of the photo-thermal environment on fruit and seed growth and development in Theobroma cacao L

End, Michelle Jane January 1990 (has links)
No description available.
4

Polygalacturonase gene expression during pod development in oilseed rape (Brassica napus L.)

Jenkins, Elizabeth January 1997 (has links)
No description available.
5

Copper and zinc uptake by celery plants grown on acidic soil amended with biosolids

Haghighi, Maryam, Pessarakli, Mohammad 11 September 2015 (has links)
For trace elements, such as copper (Cu) and zinc (Zn), the bioavailability of these elements, Cu and Zn, in biosolids is important because both are essential elements and both are potential contaminants when biosolids are land applied. A greenhouse study was conducted in factorial experiment based on a completely randomized design (CRD) with four replications on a soil treated with four rates of Cu (0, 50, 100, and 150 mg/kg) and four rates of Zn (0, 150, 300, and 450 mg/kg) on celery plants to investigate the distribution and mobility of these elements as well as growth and antioxidant changes of celery. The results of antioxidant changes were inconclusive due to irregular changes with Zn and Cu applications. However, generally the results show that Cu did not affect superoxide dismutase (SOD) or peroxidase (POD) activities in most of the treatments. On the other hand, Zn stimulated SOD and POD activities in most of the treatments. The photosynthesis rate decreased with the applications of Cu and Zn at the rates above 100 and 300 mg/kg and increased in low Cu concentration (50 mg/kg) compared to S (soil without biosolid).
6

The identification, epidemiology and control of Phytophthora megakarya on cocoa in West Africa

Luterbacher, Mark Christopher January 1994 (has links)
No description available.
7

Investigation et application des méthodes d'ordre réduit pour les calculs d'écoulements dans les faisceaux tubulaires d'échangeurs de chaleur / Investigation and application of reduced-order methods for flows study in heat exchanger tube bundles

Pomarède, Marie 07 February 2012 (has links)
Cette thèse s’intéresse à la faisabilité de la mise en place de modèles d’ordre réduit pour l’étude des vibrations sous écoulement au sein de faisceaux tubulaires d’échangeurs de chaleur. Ces problématiques sont cruciales car les systèmes étudiés sont des éléments majeurs des centrales nucléaires civiles et des chaufferies embarquées dans les sous-marins.Après avoir rappelé le fonctionnement et les risques vibratoires existants au sein des échangeurs de chaleur, des calculs complets d’écoulement et de vibrations sous écoulement ont été effectués, d’abord pour un tube seul en milieu infini, puis pour un faisceau de tubes. Ces calculs ont été menés avec l’outil CFD Code_Saturne. La méthode de réduction de modèle POD (Proper Orthogonal De-composition) a été appliquée au cas des écoulements avec la structure laissée fixe.Les résultats obtenus montrent l’efficacité de la méthode pour ces configurations, moyennant l’introduction de méthodes de stabilisation pour l’écoulement au sein du faisceau. La méthode POD-multiphasique, permettant d’adapter la méthode POD à l’interaction fluide-structure, a ensuite été appliquée. Les grands déplacements d’un cylindre seul dans la zone d’accrochage (lock-in) ont été correctement reproduits par cette méthode de réduction de modèle. De même, on montre que les grands déplacements d’un cylindre en milieu confiné dans un faisceau de tubes sont fidèlement reconstruits.Enfin, l’extension de l’utilisation de la réduction de modèle aux études d’évolution paramétrique a été testée. Nous avons d’abord utilisé la technique considérant une base POD unique pour reproduire des écoulements à divers nombres de Reynolds autour d’un cylindre seul. Les résultats confirment la prédictivité bornée à une gamme de paramètres de cette méthode. Enfin, l’interpolation de bases POD pré-calculées pour une famille de paramètres donnés, utilisant les variétés de Grassmann et permettant de générer de nouvelles bases POD, a été testée sur des cas modèles. / The objective of this thesis is to study the ability of model reduction for investigations of flow-induced vibrations in heat exchangers tube bundle systems.These mechanisms are a cause of major concern because heat exchangers are key elements of nuclear power plants and on-board stoke-holds.In a first part, we give a recall on heat exchangers functioning and on vi-bratory problems to which they are prone. Then, complete calculations leaded with the CFD numerical code Code_Saturne are carried out, first for the flow around a single circular cylinder (fixed then elastically mounted) and then for the case of a tube bundle system submitted to cross-flow. Reduced-order method POD is ap-plied to the flow resolution with fixed structures. The obtained results show the efficiency of this technique for such configurations, using stabilization methods for the dynamical system resolution in the tube-bundle case.Multiphase-POD, which is a method enabling the adaptation of POD to fluid-structure interactions, is applied. Large displacements of a single cylinder elastically mounted under cross-flow, corresponding to the lock-in phenomenon,are well reproduced with this reduction technique. In the same way, large displace-ments of a confined moving tube in a bundle are shown to be faithfully recon-structed.Finally, the use of model reduction is extended to parametric studies. First,we propose to use the method which consists in projecting Navier-Stokes equations for several values of the Reynolds number on to a unique POD basis. The resultsobtained confirm the fact that POD predictability is limited to a range of parameter values. Then, a basis interpolation method, constructed using Grassmann mani-folds and allowing the construction of a POD basis from other pre-calculated basis,is applied to basic cases.
8

Assessing the Effects of the Holidays on Body Composition and Weight Change Using Air Displacement Plethysmography

Larson, Jessyka Nicholle 01 May 2009 (has links)
This study was conducted to determine the change in weight and body composition over a 6-week holiday period. Change in body composition was measured using air displacement plethysmography technology (Bod Pod®). Thirteen men and 21 women ranging in age from 23-61 years were participants for this study. Baseline testing occurred the week of Thanksgiving Day (November 24 or 25), and the post-holiday assessment was the week after Utah State University's holiday break (January 5 or 6). Results from a nutrition and exercise questionnaire revealed a significant difference between pre-holiday and post-holiday consumption of vegetables (8.6 ± 8.3 vs. 6.2 ± 4.0), special holiday foods (1.6 ± 1.9 vs. 2.5 ± 2.1), regular soda (1.5 ± 2.2 vs. 2.2 ± 2.6), and social gatherings attended (1.6 ± 1.5 vs. 2.2 ± 1.7). There was also a statistically significant decline in the number of days per week individuals exercised pre-holiday (3.7 ± 2.0 day/week) versus post-holiday (2.6 ± 2.3 day/week). Despite these differences, there was no statistically significant difference between pre-holiday weight (74.0 ± 17.8 kg) and post-holiday weight (73.9 ± 18.1 kg), nor between pre-holiday body fat percentage (25.4 ± 9.0%) and post-holiday body fat percentage (25.4 ± 8.9%).
9

Numerical study on instability and interaction of wind turbine wakes

Sarmast, Sasan January 2014 (has links)
Numerical simulations of the Navier-Stokes equations are conducted to achieve a better understanding of the behavior of wakes generated by the wind turbines. The simulations are performed by combining the in-house developed code EllipSys3D with the actuator line technique. In step one of the project, a numerical study is carried out focusing on the instability onset of the trailing tip vortices shed from a 3-bladed wind turbine. To determine the critical frequency, the wake is perturbed using low-amplitude excitations located near the tip spirals. Two basic flow cases are studied; symmetric and asymmetric setups. In the symmetric setup a 120 degree flow symmetry condition is dictated due to the confining the polar computational grid to 120 degree or introducing identical excitations. In the asymmetric setup, uncorrelated excitations are imposed near the tip of the blades. Both setups are analyzed using proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). By analysing the dominant modes, it was found that in the symmetric setup the amplification of specific waves (traveling structures) traveling along the tip vortex spirals is responsible for triggering the instability leading to wake breakdown, while by breaking the symmetry almost all the modes are involved in the tip vortex destabilization. The presence of unstable modes in the wake is related to the mutual inductance (vortex pairing) instability where there is an out-of-phase displacement of successive helix turns. Furthermore, using the non-dimensional growth rate, it is found that the mutual inductance instability has a universal growth rate equal to Π/2. Using this relationship, and the assumption that breakdown to turbulence occurs once a vortex has experienced sufficient growth, an analytical relationship is provided for determining the length of the stable wake. This expression shows that the stable wake length is inversely proportional to thrust, tip speed ratio and the logarithmic of the turbulence intensity. In second study, large eddy simulations of the Navier-Stokes equations are also performed to investigate the wake interaction. Previous actuator line simulations on the single model wind turbine show that the accuracy of the results is directly related to the quality of the input airfoil characteristics. Therefore, a series of experiments on a 2D wing are conducted to obtain high quality airfoil characteristics for the NREL S826 at low Reynolds numbers. The new measured data are used to compute the rotor performance. The results show that the power performance as well as the wake development behind the rotor are well-captured. There are, however, some difficulties in prediction of the thrust coefficients. The continuation of this work considers the wake interaction investigations of two turbines inline (full-wake interaction) and two turbines with spanwise offset (half wake interaction). It is demonstrated that the numerical computations are able to predict the rotor performances as well as the flow field around the model rotors, and it can be a suitable tool for investigation of the wind turbine wakes. In the last study, an evaluation of the performance and near-wake structure of an analytical vortex model is presented. The vortex model is based on the constant circulation along the blades (Joukowsky rotor) and it is able to determine the geometry of the tip vortex filament in the rotor wake, allowing the free wake expansion and changing the local tip vortex pitch. Two different wind turbines have been simulated: a wind turbine with constant circulation along the blade and the other setup with a realistic circulation distribution, to compare the outcomes of the vortex model with real operative wind turbine conditions. The vortex model is compared with the actuator line approach and the presented comparisons show that the vortex method is able to approximate the single rotor performance and qualitatively describe the flow field around the wind turbine but with a negligible computational effort. This suggests that the vortex model can be a substitute of more computationally-demanding methods like actuator line technique to study the near-wake behavior. / <p>QC 20141010</p>
10

Studie dopadů destinace Singltrek pod Smrkem na region

Kamenický, Matěj January 2016 (has links)
This thesis deals with the impact analysis of realization the destination site of trails Singltrek pod Smrkem in Nové Město pod Smrkem and surroundings on nearby region. Results are based on surveys among visitors of the trails, residents of nearby municipalities and entrepreneurs in the region. For a purpose of the evaluation of the date the the cost-benefit analysis was used. Among the benefits of the project there is the reduction of unemployment, utility from using the service for the visitors or increased profits of local businesses. With the method of internal rate of return that was calculated on 20,6 %. In conclusion it was found that benefits are higher than costs and all stakeholders can be satisfied. In the end were submitted some recommendations for the sustaining of the project and its development because it can be threatened by the newly founding destination site with the same focus.

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