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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

SMEs Internationalization From Developing Countries : Challenges and Barriers

Pillalamarri, Kalyani, Mohamed, Mekki January 2016 (has links)
Small and medium-sized enterprises (SMEs) play a major role in the development of the nation's economy by providing employment and creating the economic growth. The management of the companies that are going international considers different motives before taking the step into the international market. The internationalization process involves risks and uncertainty significantly effected by challenges and barriers to SMEs from developing countries.
2

A Global Enhanced Vibrational Kinetic Model for Radio-Frequency Hydrogen Discharges and Application to the Simulation of a High Current Negative Hydrogen Ion Source

Averkin, Sergey Nikolaevich 02 April 2015 (has links)
A Global Enhanced Vibrational Kinetic (GEVKM) model is presented and applied to the simulation of a new High Current Negative Hydrogen Ion Source (HCNHIS) developed by Busek Co. Inc. and Worcester Polytechnic Institute. The HCNHIS consists of a high-pressure radio-frequency discharge (RFD) chamber in which the main production of high-lying vibrational states of the hydrogen molecules occurs, a bypass system, and a low-pressure negative hydrogen ion production (NIP) region where negative ions are generated by the dissociative attachment of low energy electrons to rovibrationally excited hydrogen molecules. The GEVKM is developed from moment equations for multi-temperature chemically reacting plasmas and for a cylindrical geometry of an inductively coupled discharge chamber. The species included into the model are ground state hydrogen atoms H and molecules H2, 14 vibrationally excited hydrogen molecules H2(v), v=1-14, electronically excited hydrogen atoms H(2), H(3), ground state positive ions H+, H2+, H3+, ground state negative ions H-, and electrons e. The space-averaged steady-state continuity equations coupled with the electron energy equation, the total energy equation and heat transfer to the chamber walls, are solved simultaneously in order to obtain the space-averaged number densities of the plasma components, the electron and heavy particle temperatures as well as the wall temperature. The GEVKM is supplemented by a comprehensive set of surface and volumetric chemical processes governing vibrational and ionization kinetics of hydrogen plasmas. The GEVKM is verified and validated in the low pressure, in the intermediate to high-pressure (1-100 Torr) and high absorbed power density (8.26-22 W/cm3) regimes by comparisons with the numerical simulations and experimental measurements. The GEVKM is applied to the simulation of the RFD chamber of the HCNHIS. The GEVKM predictions of negative hydrogen ions number densities and electron temperatures in the RFD chamber of the HCNHIS are used to estimate the negative hydrogen ion current using the Bohm flux approximation. The estimated negative current compare well with the Faraday Cup measurements and provide additional validation of the model. The GEVKM is used in a parametric investigation of the RFD chamber of HCNHIS-2 with hydrogen inlet flow rates 5-1000 sccm and absorbed powers 200-1000 W.
3

Improving Complementary Methods To Predict Evapotranspiration For Data Deficit Conditions and Global Applications Under Climate Change

Anayah, Fathi M. A. 01 August 2012 (has links)
A reliable estimate of evapotranspiration (ET) in river basins is important for the purpose of water resources planning and management. ET represents a significant portion of rainfall in the water budget; therefore, the uncertainty in estimating ET can lead to the inaccurate prediction of water resources. While remote sensing techniques are available to estimate ET, such methods are expensive and necessary data may not be readily available. Classical methods of estimating ET require detailed land use/cover information that are not readily available in rural river basins. Complementary methods provide simple and reliable approaches to estimate ET using meteorological data only. However, these methods have not been investigated in detail to assess the overall applicability and the needs for revisions if any. In this work, an improved approach to use the complementary methods using readily available meteorological data is presented. The methodology is validated using 34 global FLUXNET sites with heterogeneous land use/cover, climatic, and physical conditions. The method was compared with classical methods using Ghana as a study area where original pioneering studies of ET have been performed. The work was extended to develop global maps of ET and water surplus (precipitation - ET) for the 20th century followed by climate change-induced 21st century estimates for 2040-2069 and 2070-2099 periods. The emission scenario used was the moderate A1B with the global climate models CGCM3.1 and HADGEM1. The results were assessed at different scales from global to regional such as for potential outcomes of climate change on ET and water surplus.
4

An Investigation of a Pt-Pd Diesel Oxidation Catalyst

Khosravi Hafshejani, Milad Unknown Date
No description available.
5

Wind Speed Prediction using Global and Regional Based Virtual Towers in CFD Simulations

Moubarak, Roger January 2011 (has links)
Wind farm assessment is a costly and time consuming process when it is planned by traditional methods such as a met mast. Therefore, new models have been established and used for the wind farm assessment to ease the process of wind farm planning. These models are Global-regional models which add to cost efficiency and time saving. There are several types of these models in the market that have different accuracy. This thesis discusses and uses in simulations Global – regional model data outputs from European Centre for Medium-Range Weather Forecasts (ECMWF), Weather Research Forecast WRF and ECMWF, which is currently producing ERA-Interim, global reanalysis of the data-rich period since 1989 .The goal of the master's thesis is to see whether it is useful and efficient to use Global – regional weather model data such as the Era Interim Global Reanalysis Model data for wind assessment by comparing it with the real data series (met mast) located in Maglarp, in the south of Sweden.The comparison shows that in that specific area (hindcast) at Maglarp, in the south of Sweden, very promising results for planning a wind farm for a 100m, 120m and 38m heights.
6

Multimodelové srovnání kvality předpovědi počasí / Multimodel weather forecast comparison

Žáček, Ondřej January 2018 (has links)
This thesis analyses comparison and verification of three global numeric weather models, GFS, ECMWF, NEMS. The research subjects are make comparison of their 48-hour forecast with, for this thesis created, index correspondence of models and evaluate predictability of weather. Next, introduce basic verification methods and their application to forecast verification, from previously mentioned models, against surface observations with resolution 2 ř x 2 ř lat/lon between 1. 6. 2017-28. 2. 2018. Results show, that the worst predictability is at areas with continental glaciers, extensive world mountain ranges and at ITCZ area. The best predictability is observed in subtropical anticyclones over the oceans. Verification of temperature we find out significant smoothing of diurnal cycle in all three models. Biases of relative humidity are strongly negative corelated with temperature bias, skill score for relative humidity is worse than for temperature. Performance of mean sea level pressure is the best for all verification metrics from all analysed quantities. Wind speed is for most world overestimated. Results of 3-hour precipitation depends on treshold. Models overestimate frequency of low intensity precipitation, opposite results are observed for high intensity precipitation, break occur at interval...
7

GEOGloWS HydroViewer: Open Software-as-a-Service for Localizing Global Hydrologic Forecasts of the Group on Earth Observations Global Water Sustainability Initiative

Ashby, Kyler Ralph 02 April 2021 (has links)
Earth observation data is increasingly ubiquitous, easily accessible, freely available, and generally usable due to improvements in software, data standards, network infrastructure, and national policies. As a result, greater opportunities arise for using these data in a wider field of application including decision support for local and regional environmental and water resources management efforts. In parts of the world where in situ data are less readily available, global Earth observation data used in such decision support tools can be a boon to underfunded government and private water management agencies. The United Nations Group on Earth Observations Global Water Sustainability initiative (GEOGloWS) works to coordinate such solutions, bringing global water management capabilities to local decision makers. The recent development and deployment of a global hydrologic modelling system based on historical simulations and daily ensemble forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) using Earth observations and streamflow routing on every river of the world results in a highly informative and potentially transformative dataset for users at local scales. However, for this data to reach its full potential at the local level, it needs to be subsetted at a regional or local scale, presented in a local geographic context, and interpreted in terms of local water management challenges. Furthermore, this subsetting allows for customization to support the way information is used and the kinds of decisions that are made. This paper presents the design, development, and experimental testing of the GEOGloWS HydroViewer, which is an open source, web-based software that effectively localizes global ECMWF forecasts to meet the needs of water managers and decision makers through subsetting the mapping and modelling services and supporting other customization as needed. The unique Software-as-a-Service (SaaS) deployment method, developed and tested here, allows for individual water management agencies to automatically generate custom HydroViewer applications that can be managed and/or customized depending on need and capacity in-country without reliance on external software and capacity, removing typical interdependence relationships that often define technology transfer to developing countries.
8

STUDY OF TRANSIENT BEHAVIOR OF THE EVAPORATOR OF THE MICRO LOOP HEAT PIPE AND MODIFICATIONS TO THE EXISTING GLOBAL MODEL

PONUGOTI, PRIYANKA 02 October 2006 (has links)
No description available.
9

Modelling the Formation and Propagation of Orographic Rossby Waves / Modellering av formation och propagering av orografiska Rossbyvågor

Jonsson, Eskil January 2017 (has links)
Orographic Rossby waves are the main mechanism by which the jet streams meander aroundthe Earth and have possibly far-reaching impacts on weather and climate (chapter 1). Hence,they are of particular importance to study and this project should serve as a starting point inwhat to consider when trying to model these waves. For example, we have to account forpressure gradients, Coriolis effect, orography, potential vorticity conservation and also Earth’scurvature at this scale. These are covered in detail in ch. 2 and adapted to the Shallow WaterEquations. In addition, some entry-level numerical techniques for solving these equations arepresented throughout ch. 2.4 and then implemented for the global-scale Shallow WaterEquations with conserved potential vorticity in ch. 3. The model is validated to work for typicalshallow water flows in a bath tub and passes common tests like the Gaussian curve test (ch.4.1). However, when considering atmospheric flows (ch. 4.2) it becomes evident that ourmodel, as well as our numerical methods are lacking and cannot reproduce Rossby waves ina stable manner. Hence, a heavily modified version of Hogan’s model (Hogan, n.d) isemployed with a simplified numerical scheme. With these corrections, orographic Rossbywaves appear to naturally form at appropriate locations. However, they do not fully exhibit theexpected behaviours discussed in ch. 2.2. Even Hogan’s model appears to have severelimitations as waves propagate in the wrong direction. Hence, this study is not complete andwarrants further development in order to be useful. / Orografiska Rossby-vågor är den huvudsakliga mekanismen genom vilken jetströmmarnaslingrar runt jorden och kan ha en omfattande inverkan på väder och klimat (kapitel 1). Därförär de av särskild betydelse att studera och detta projekt bör fungera som en utgångspunkt förvad man måste överväga när man försöker modellera dessa vågor. Till exempel så måste vi tahänsyn till tryckgradienter, Coriolis-effekten, orografi, potentiell vorticitetsbevarande och ävenjordens krökning på denna skala. Dessa beskrivs i detalj i kap. 2 och anpassas tillrörelseekvationerna för grunt vatten (Saint-Venant-ekvationerna). Därefter presenteras någranumeriska tekniker på grundläggande nivå för att lösa dessa ekvationer i kap. 2.4, varvid desedan implementeras för de globala Saint-Venant-ekvationerna med bevarad potentiellvorticitet i kap 3. Modellen är validerad för typiska grunda vattenflöden i ett badkar ochpasserar vanliga numeriska tester så som Gauss-kurvtestet (kap. 4.1) och bore-testet. Mennär vi överväger atmosfäriska flöden (kap. 4.2) blir det tydligt att våra modeller och numeriskametoder är primitiva och inte kan reproducera Rossby-vågor på ett stabilt sätt. Därmed,modifierar vi Hogans modell (Hogan, n.d) för att passa vår modell vilket resulterar orografiskaRossby-vågor. Dock så är dessa förskjutna och stämmer inte riktigt överens med teorin i kap.2.2. Även Hogans modell visar sig ha allvarliga begränsningar då vågorna propagerar i felriktning. Därmed är denna studie ej komplett och kräver ytterligare utveckling för att varaanvändbar.
10

Dynamo Magnétohydrodynamique en champ moyen

Simard, Corinne 06 1900 (has links)
De nos jours, il est bien accepté que le cycle magnétique de 11 ans du Soleil est l'oeuvre d'une dynamo interne présente dans la zone convective. Bien qu'avec la puissance de calculs des ordinateurs actuels il soit possible, à l'aide de véritables simulations magnétohydrodynamiques, de résoudre le champ magnétique et la vitessse dans toutes les directions spatiales, il n'en reste pas moins que pour étudier l'évolution temporelle et spatiale de la dynamo solaire à grande échelle, il reste avantageux de travailler avec des modèles plus simples. Ainsi, nous avons utilisé un modèle simplifié de la dynamo solaire, nommé modèle de champ moyen, pour mieux comprendre les mécanismes importants à l'origine et au maintien de la dynamo solaire. L'insertion d'un tenseur-alpha complet dans un modèle dynamo de champ moyen, provenant d'un modèle global-MHD [Ghizaru et al., 2010] de la convection solaire, nous a permis d'approfondir le rôle que peut jouer la force électromotrice dans les cycles magnétiques produits par ce modèle global. De cette façon, nous avons pu reproduire certaines caractéristiques observées dans les cycles magnétiques provenant de la simulation de Ghizaru et al., 2010. Tout d'abord, le champ magnétique produit par le modèle de champ moyen présente deux modes dynamo distincts. Ces modes, de périodes similaires, sont présents et localisés sensiblement aux mêmes rayons et latitudes que ceux produits par le modèle global. Le fait que l'on puisse reproduire ces deux modes dynamo est dû à la complexité spatiale du tenseur-alpha. Par contre, le rapport entre les périodes des deux modes présents dans le modèle de champ moyen diffère significativement de celui trouvé dans le modèle global. Par ailleurs, on perd l'accumulation d'un fort champ magnétique sous la zone convective dans un modèle où la rotation différentielle n'est plus présente. Ceci suggère que la présence de rotation différentielle joue un rôle non négligeable dans l'accumulation du champ magnétique à cet endroit. Par ailleurs, le champ magnétique produit dans un modèle de champ moyen incluant un tenseur-alpha sans pompage turbulent global est très différent de celui produit par le tenseur original. Le pompage turbulent joue donc un rôle fondamental au sein de la distribution spatiale du champ magnétique. Il est important de souligner que les modèles dépourvus d'une rotation différentielle, utilisant le tenseur-alpha original ou n'utilisant pas de pompage turbulent, parviennent tous deux à produire une dynamo oscillatoire. Produire une telle dynamo à l'aide d'un modèle de ce type n'est pas évident, a priori. Finalement, l'intensité ainsi que le type de profil de circulation méridienne utilisés sont des facteurs affectant significativement la distribution spatiale de la dynamo produite. / It is generally agreed upon that the 11-year magnetic cycle of the Sun arises through the action of an internal dynamo operating in the convective zone, and perhaps also immediately beneath it. Although the computing power of current supercomputers is sufficient to allow fairly realistic magnetohydrodynamical simulations of this dynamo process, to study the temporal and spatial evolution of the large-scale solar magnetic field over long timescales, it remains advantageous to work with simpler models. Thus, to better understand the physical mechanisms at the origin and maintenance of the solar dynamo, we used a simplified formulation, known as a mean-field model. By using a complete alpha-tensor extracted from a global MHD model of solar convection [Ghizaru et al., 2010] as input to a kinematic axisymmetric mean-field dynamo model [Charbonneau & MacGregor, 1997], it becomes possible to study the effect of the electromotive force on the magnetic cycles produced by the global model. In this way, we are able to reproduce some of the observed characteristics of the Ghizaru et al., 2010 simulation, in particular magnetic cycles. The axisymmetric magnetic field produced by the mean-field dynamo model exhibits two distincts dynamo modes. These modes, with similar periods, are present and peak at substantially at the same radii and latitudes as the sonlly-averaged magnetic fields extracted from the global model. Thanks to the spatial complexity of the alpha-tensor, we can reproduce these two dynamo modes. In contrast, the ratio of the periods of the two modes present in the mean field model differs significantly from that found in the global model. In addition, the accumulation of strong magnetic fields at the base of the convective zone disappears in a model where differential rotation has been removed. This suggests that differential rotation plays a significant role in the accumulation of magnetic fields in this region. Furthermore, removing the turbulent pumping component of the alpha-tensor produces a very different magnetic field cycle. Therefore, turbulent pumping plays a crucial role in the spatial distribution of the magnetic field. It is important to underline that the models without differential rotation, with or without turbulent pumping, both succeed in producing an oscillatory dynamo using only the turbulent electromotive force. However, the dynamos materializing in these modified models are significantly different from that using the full alpha-tensor. Finally, both the intensity and form of meridional circulation profiles are significant factors affecting the dynamo modes.

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