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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.
41

New Methods in Finding Binary Constant Weight Codes

Taub, David January 2007 (has links)
<p>This thesis presents new methods for finding optimal and near-optimal constant weight binary codes with distance d and weight w such that d=2(w-1). These methods have led to the discovery of a number of new codes which are being submitted for publication. Improvements in methods for generating lexicographic codes are also discussed, with suggestions for further research in this area.</p>
42

Reduced models for batch and continuous distillation

Bryson, James R. January 1993 (has links)
No description available.
43

Minimisation of filling time in resin transfer moulding

Semling, M. January 1999 (has links)
No description available.
44

On the influence of the cosmological constant on trajectories of light and associated measurements

Lebedev, DMITRI 01 October 2013 (has links)
In this thesis we review and build on the common methods used to analyze null geodesics in Schwarzschild de Sitter space. We present a general technique which allows finding measurable intersection angles of null trajectories analytically, and as one of its applications we establish a general relativistic aberration relationship. The tools presented are used to analyze some standard setups of gravitational deflection of light and gain a clear understanding of the role that the cosmological constant, Λ, plays in gravitational lensing phenomena. Through reviewing some recent papers on the topic with the present results in mind, we attempt to explain the major sources of disagreement in the ongoing debate on the subject, which started with Rindler and Ishak’s original paper, regarding the influence of Λ on lensing phenomena. To avoid ambiguities and room for misunderstanding we present clear definitions of the quantities used in the present analysis as well as in other papers we discuss. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2013-09-30 21:18:26.762
45

The Cosmological Constant Problem from a Brane--World Perspective

Stefan Foerste, Zygmunt Lalak, Stephane Lavignac, Hans Peter Nilles, Andreas.Cap@esi.ac.at 20 June 2000 (has links)
No description available.
46

The BIG ghost

von Strauss, Mikael January 2011 (has links)
In this thesis we present work done in an analysis of models of brane induced gravity. These are higher dimensional generalizations of Einstein's General relativity where our universe is considered as a brane in a higher dimensional bulk and where the gravitational dynamics on the brane is enhanced. This provides a modification of gravity on the brane as compared to ordinary general relativity, primarily at very large distances. These models are therefore very interesting for adressing the cosmological constant problem. Even though the basic setup is natural to consider from the perspective of effective field theory and also follow from certain string theoretical considerations, the models have been plagued by inconsistencies in the form of unstable modes. In particular, a ghostlike and tachyonic scalar mode appears already at the linear level in a perturbative treatment. In order to gain a deeper insight into the nature of these consistency problems we have revisited the models, performing a more extensive analysis of the generic models than has previously been done. We have worked entirely in a gauge invariant formalism in order not to be obscured by gauge issues. We have also incorporated an effective thickness of the brane in our analysis and performed an explicit analysis of the effect of contributions from the extrinsic geometry. Although our analysis has been carried out at the linear level in a perturbative treatment we are able to get a deeper understanding of the unstable mode and illuminate some of the difficulties of these models that would likely persist even in a full nonlinear analysis.
47

New Methods in Finding Binary Constant Weight Codes

Taub, David January 2007 (has links)
This thesis presents new methods for finding optimal and near-optimal constant weight binary codes with distance d and weight w such that d=2(w-1). These methods have led to the discovery of a number of new codes which are being submitted for publication. Improvements in methods for generating lexicographic codes are also discussed, with suggestions for further research in this area.
48

A Synthesizer of Constant Matrix Multipliers in Galois Field GF(2^n)

Tu, Chia-Shin 12 July 2004 (has links)
The arithmetic operations in most digital system are in the conventional binary number systems. However, the finite field arithmetic has also been widely used in applications of cryptography and communication channel coding. For example, finite field constant multiplication is applied to the advanced encryption standard (AES) and in the Reel-Solomon code. In this thesis, we develop a synthesizer that can automatically generate optimized gate-level netlists for constant matrix multiplication in Galois Field GF(2^n). The logic minimization is based on the a new common-factor elimination (CSE) algorithm that can efficiently finds the shared common factors among all the bit-level Boolean equations. Both the area and speed performance are considered during the logic optimization process. Experimental results show that the synthesized circuits have better area and/or speed performance compared with those obtained using Synopsys logic synthesis tools.
49

The effect of CuInSe2 thin film property of ZnSeTe window layer

Ho, Hsieh-Chia 27 July 2002 (has links)
Abract This paper concems studies of CIS solar cell based on ZnSe an ZnSeTe window layer. ZnSe an ZnSeTe films are grown by Molecular Beam Deposition (MBD).This research is important for several reasons : (1)Development of non-cadmium buffer layer may be essential for CIS solar cells to be accepted in the marketplace ; (2)Development of direct ZnO/CIS cells could lead to a simplified cell (3)knowledge gained in investigations of ZnO and ZnSeTe buffer layer may help us understand the unique role CdS plays in CdS/CIS solar cell .
50

Dielectric Properties Research On Bi1-xPbxFeO3

Chang, Chin-chien 22 August 2008 (has links)
With combination of the both ferroelectric and ferromagnetic and mutural coupling properties, multiferroics attracts a lot of researcher¡¦s attentions. Among these very popular materials, such as REMnO (113 series, 125 series), BiFeO3 etc¡K , the BiFeO3 interests us the most for it manifests multiferroic effects above the room temperature. However, the pure BiFeO3 phase is very difficult to form and a serious lost of Bi creates complex grain boundaries that produces enormous electric leaking. In this study, Pb is doped into BiFeO3 in Bi sites and we hope this doping effect may increase the stability and the ferroelectricity of Bi1-xPbxFeO3. It is found that the crystal structure is changed dramatically, because of the doping of Pb, from the rhombohedra structure of the parent pure BiFeO3 to the cubic structure of Bi0.85Pb0.15FeO3. By the Pb doping, the compounds exhibit free from impurity phases and the dielectric constants are enhanced qualitatively to the doping levels.

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