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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.
21

Dual-Frequency Microstrip Arrays with a Dual-frequency Feed Network

Huang, Chien-Chin 15 June 2000 (has links)
No
22

Fabrication of Modifiable Dual-Mode Band-pass Filter on Al2O3 Substrate

Lee, Tsung-Hsien 03 July 2003 (has links)
Recently, the evolutions of wireless communication systems are growing rapidly to satisfy the personal communication requirements. Compact, small size, low cost, easy fabrication, and multi-function are the major developing trends among these modern wireless communication devices. In this research, high quality Al2O3 ceramic materials are used as a substrate to fabricate modifiable dual-mode bandpass filters with the advantages of light weight, small size, and high performance. Dual mode cavity and dielectric resonator filters are the mainstay of satellite communications. In this research, a class generation of planar dual mode filters are introduced which significantly offers the advantages of small size, light weight, and low cost. The proposed bandpass filters are first simulated on Al2O3 (er=9.4) substrate for microwave frequency, and the proposed structures consist one square-typed patch, one circle-typed patch, or one meander-typed patch. Each pattern is connected with two 50£[ microstrip line, one for input and another for output. Two 50£[ microstrip lines are connected to the central of the patch with two notches, and the patch will act as the elliptic-function bandpass filters. Before the fabrication of a bandpass filter, IE3D microwave simulation software is used to simulate the designed filters. With a metal mask, the filter patterns are fabricated on the Al2O3 substrate by using evaporation method. It is found that as the length of notches increase, the three of structures band-pass filters reveal better filtering effect, i.e., the smaller insertion loss (S21), and larger return loss (S11), and the perturbation in the patch facilitates coupling between two orthogonal modes within the resonator, i.e., the perturbation size can modify bandwidth and resonator frequency. After the measurement of the fabricated filters, it is found that the measured results will match the simulated results.
23

Evaluation of liquid lift approach to dual gradient drilling

Okafor, Ugochukwu Nnamdi 10 October 2008 (has links)
In the past, the oil and gas industry has typically used the single gradient system to drill wells offshore. With this system the bottom hole pressure was controlled by a mud column extending from the drilling rig to the bottom of the wellbore. This mud column was used to achieve the required bottom hole pressure. But, as the demand for oil and gas increased, the industry started exploring for oil and gas in deep waters. Because of the narrow margin between the pore and fracture pressures it is somewhat difficult to reach total depth with the single gradient system. This led to the invention of the dual gradient system. In the dual gradient method, heavy density fluid runs from the bottom hole to the mudline and a low density fluid from the mudline to the rig floor so as to maintain the bottom hole pressure. Several methods have been developed to achieve the dual gradient drilling principle. For this research project, we paid more attention to the liquid lift, dual gradient drilling (riser dilution method). This method of achieving dual gradient drilling was somewhat different from the others, because it does not utilize elaborate equipment and no major changes are made on the existing drilling rigs. In this thesis the technical feasibility of using the liquid lift method over the other methods of achieving dual gradient drilling was determined. A computer program was developed to simulate the wellbore hydraulics under static and dynamic conditions, injection rate and base fluid density required to dilute the riser fluid and finally, u-tubing phenomena. In this thesis we also identified some problems associated with the liquid lift method and recommendations were made on how these problems can be eliminated or reduced. Emphases were placed on the effect of u-tubing, injection rate of base fluid at the bottom of the riser and well control issues facing this system.
24

Role stressors, interrole conflict, and well-being the moderating influence of spousal support and coping behaviors among employed parents: a replicative study /

Tatman, Anthony W. January 2001 (has links) (PDF)
Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2001. / Includes bibliographical references.
25

The effect of a novel dual-task exercise program for balance, mobility, gaze, and cognition skills in community dwelling older adults: A pilot study

Alhasani, Rehab 04 June 2015 (has links)
This thesis aimed to investigate the benefit of game-based dual-task recumbent bicycle (DT-RC) training among older adults. In addition, the thesis examined the change in cardiac fitness over an 8-week training program. Eleven healthy older adults (70-80 years old) were recruited and received an 8-week dual-task training program; combines a recumbent bicycle with interactive cognitive video games. Outcome measures were collected pre and post the intervention and included measures to assess COP for core balance, spatial-temporal gait variables, performance in visual tracking and cognitive games, neuropsychological tests and HR to workload ratio. Results showed a significant improvement in COP excursion, head tracking and success rate for cognitive games, trails making test and HR to workload ratio decreased by 44%. No significant effects were found for spatial-temporal gait variables. This study shows that the DT-RC program has beneficial effects on dual-task functions and cardiac fitness among healthy older adults.
26

Use of a dual task paradigm to examine the effects of age on mobility and cognitive performances

Kanitkar, Anuprita 27 August 2014 (has links)
The increase in the aging population has become one of the most important problems of our society in last few decades. As people grow older, they are at risk of falling and consequent injuries due to the effects of aging. A fall may be the first indication of an undetected illness related to the effects of aging. This study demonstrates the effects of aging on balance, spatio-temporal gait parameters, gaze stability, and cognitive skills under single task conditions and during dual-tasks conditions. In the present study, we included following three groups: Group 1: 30 young healthy adults (aged 20 ± 3 years); Group 2: 30 adults (aged 61.4 ± 4.4 years); Group 3: 30 older adults (aged 75 ± 4.5 years). A computer game based rehabilitation platform has been developed and was used for the single and dual task performance in standing and during treadmill walking. We observed that there was a significant age effect while dual tasking on standing balance, spatial and temporal gait parameters, gaze performance, and cognitive task performance. To conclude, this study shows a vast decline in walking and standing balance and ability to divide attention during dual tasking between the age groups 55-70 years and 71- 85 years and compares both these age groups with the more normative, healthy, young and athletic, 20-30 years old population.
27

Dual-Energy-CT physikalische Modelle und Anwendungen

Sedlmair, Martin Ulrich January 2009 (has links)
Zugl.: München, Univ., Diss., 2009
28

Dual-Energy-CT : physikalische Modelle und Anwendungen /

Sedlmair, Martin Ulrich. January 2010 (has links)
Zugl.: München, Universiẗat, Diss., 2009.
29

The Scriptural validity of working women

Mandeville, V. Ann. January 1986 (has links)
Thesis (M.A.B.S.)--Multnomah School of the Bible, 1986. / Includes bibliographical references (leaves 50-59).
30

Impact de la libéralisation commerciale au Sénégal : évaluation de l’accord de partenariat économique sur l’agriculture et les ménages sénégalais. / Impact of trade liberalisation in Senegal : assessment of economic partnership agreement on agriculture and senegalese households

Fall, Cheickh Sabidou 16 November 2016 (has links)
Cette thèse propose une évaluation des effets potentiels de l’Accord de partenariat économique (APE) entre l’Union européenne (UE) et l’Afrique de l’Ouest sur l’agriculture et les ménages sénégalais. En effet, après plus de 12 ans de discussions, la Communauté Économique des États de l’Afrique de l’Ouest (CEDEAO) dans sa majorité a signé l’APE avec l’UE, le volet commercial de l’Accord de Cotonou. L’APE est ainsi devenu le nouveau cadre de coopération économique et commercial entre l’UE et le Sénégal avec l’établissement à terme d’une zone de de libre-échange réciproque entre l’UE et les pays ACP, cependant asymétrique et mettant ainsi fin au régime des conventions de Lomé, qui était basé sur les préférences commerciales non réciproques. Cette étude est basée sur le modèle d’équilibre général calculable (MEGC) uni-pays développé par Bouët et al (2001). Il s’agit à la base d’un modèle statique avec l’hypothèse de concurrence parfaite et non monétaire qui décrit une petite économie ouverte comme le Sénégal. En effet, le Sénégal est un pays en développement importateur net de produits alimentaires et très dépendant du commerce international notamment pour couvrir ses besoins alimentaires. Ce MEGC a été enrichi par l’introduction de l’approche théorique « Dual-Dual » élaborée par Stifel et Thorbecke (2003) pour tenir compte des spécificités de la plupart des économies africaines comme le Sénégal notamment un secteur informel très développé et la migration rural-urbain d’une part et d’autre part parce que la quasi-totalité des MEGC utilisés pour étudier l’économie sénégalaise n’intègre pas ces aspects structurels. De plus, pour bien prendre en compte l’APE dans nos simulations nous avons rajouté deux étages au niveau des exportations et des importations pour bien distinguer les origines/destinations CEDEAO et UE. Le modèle utilisé est calibré sur une matrice de comptabilité sociale (MCS) pour l’année 2006 construite dans le cadre de cette thèse. Pour appréhender les effets sur les ménages, trois enquêtes ménages ont été utilisées pour identifier 78 ménages représentatifs. Pour les données tarifaires, le nouveau tarif extérieur commun de la CEDEAO (TEC CEDEAO) en vigueur depuis le 1er janvier 2015 a été utilisé. Les résultats ont révélé que l’APE est une réforme commerciale qui n’offre pas des perspectives de gains réels pour le Sénégal car elle implique essentiellement une ouverture de l'économie sénégalaise aux seuls produits européens et n'améliore pas l'accès de l'économie sénégalaise aux économies du reste du monde. Sur le plan des analyses de bien-être, l’APE ne permet pas de réduire la pauvreté et les inégalités / This PHD thesis proposes an assessment of the potential effects of the Economic Partnership Agreement (EPA) between the European Union (EU) and West Africa on Senegalese agriculture and households. Indeed, after 12 years of negotiations, the Economic Community of West African States (ECOWAS) in its majority signed the EPA with the EU, the trade component of the Cotonou Agreement. Thus, the EPA has become the new framework for economic and trade cooperation between the EU and Senegal. The objective to the end is the establishment of a reciprocal free trade area between the EU and ACP countries, however asymmetrical and putting an end to the Lome Agreement, which was based on non-reciprocal trade preferences. This study is based on the Single country computable general equilibrium model (CGE) developed by Bouët et al (2001). It is a static model with the assumption of perfect competition and non-monetary, which describes a small open economy such as Senegal. Indeed, Senegal is a net food-importer developing country and very dependent on international trade specially to cover its food needs. This CGE was enriched by the introduction of the "Dual-Dual" theoretical approach developed by Stifel and Thorbecke (2003) to reflect the specificities of most African economies like Senegal i.e. a large informal sector and migration rural-urban firstly and secondly because almost all the CGE models used to study the Senegalese economy does not incorporate these structural aspects. In addition, to better capture the EPA in our simulations we added two stages in exports and imports modelling to distinguish the origins / destinations ECOWAS and EU. The model is calibrated on a 2006 Social Accounting Matrix (SAM) built as part of this thesis. To understand the effects on households, three household surveys were used to identify 78 representative households. For tariff data, the new ECOWAS Common External Tariff (ECOWAS CET) launched on January 1st 2015 was used. The results revealed that the EPA is a trade reform that offers no real earnings prospects for Senegal because it essentially implies openness of the Senegalese economy only to European products and does not improve the access of Senegalese economy to other economies of the World. In terms of welfare analysis, the EPA did not reduce poverty and inequality.

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