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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.
71

THE BRIDGE FUNCTION TELEMETRY SYSTEM

Qishan, Zhang 11 1900 (has links)
International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Based on the theory of orthogonality, two orthogonal multiplex systems called frequency division multiplexing(FDM) and time division multiplexing(TDM) have long been developed. Therefore, many people tend to think that these two systems represent the ONLY two multiplexing methods that satisfy the orthogonal condition. However, after years of research, we've discovered a new kind of orthogonal functions called Bridge functions. The Bridge functions have the every promise of being the basis for constructing an entirely new kind of telemetry system, which has been named as sequency division multiplexing(SDM). Since the Bridge functions are the mathematical basis of the new telemetry system, we will give a summary of the Bridge functions at first. We have successfully constructed an experimental prototype called BAM-FM system in our laboratory. The main ideas, block diagram, operational principles, and technical problems are discussed in this paper. All our work has proved that SDM has not only research interests, but also practical value.
72

THE BRIDGE FUNCTION TELEMETRY SYSTEM

Qishan, Zhang 11 1900 (has links)
International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Based on the theory of orthogonality, two orthogonal multiplex systems called frequency division multiplexing (FDM) and time division multiplexing (TDM) have long been developed. Therefore, many people tend to think that these two systems represent the ONLY two multiplexing methods that satisfy the orthogonal condition. However, after years of research, we've discovered a new kind of orthogonal functions called Bridge functions. The Bridge functions have the every promise of being the basis for constructing an entirely new kind of telemetry system, which has been named as sequency division multiplexing (SDM). Since the Bridge functions are the mathematical basis of the new telemetry system, we will give a summary of the Bridge functions at first. We have successfully constructed an experimental prototype called BAM-FM system in our laboratory. The main ideas, block diagram, operational principles, and technical problems are discussed in this paper. All our work has proved that SDM has not only research interests, but also practical value.
73

Cyclic prefix in OFDM systems

Chen, Zhiqiang, 陳志強 January 2007 (has links)
published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
74

Symbol synchronization in OFDM-based systems

Pan, Xinyue., 潘新月. January 2007 (has links)
published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy
75

Adaptive multi-carrier techniques for cellular and local area networks

Keller, Thomas January 1999 (has links)
No description available.
76

The distinguished guests of giants

Mathwin, Christopher Richard January 2016 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016. / The convenient pictorial descriptions of the half-BPS and near-BPS sectors of the AdS=CFT equivalent theories of N = 4, D = 4 super Yang-Mills and D = 10 Type IIB superstring theory on AdS5 S5 are exploited in this thesis by using Schur polynomials labelled by Young diagrams as a basis for the gauge invariant operators in the eld theory. We use a \Fourier transform" on these operators to construct asymptotic eigenstates of the dilatation operator, the spectrum of which agrees precisely with the rst two leading order terms in the smallcoupling expansion of the exact result determined by symmetry. Motivated by the geometric description of the systems of open strings with magnon excitations to which the operators are dual, we propose a simple and minimal all-loop expression that interpolates between anomalous dimensions computed in the gauge theory and energies computed in the string theory. The connection to the string theory result provides the insight necessary to understand the interpretation of our Gauss graphs in the magnon language. Symmetry determines the two-body scattering matrix for the magnons up to a phase, and it is demonstrated that integrability is spoiled by the boundary conditions on the open strings. The Schur polynomial construction is then applied to the study of closed strings on a class of half- BPS excitations of the AdS5 S5 background. The string theory predictions for the magnon energies are again reproduced by calculating the anomalous dimensions of particular linear combinations of our operators. Group theoretic quantities which can be read o the Young diagram labels provide the correct modi cation of terms in the dilatation action to account for the energies of magnons at di erent radii on the LLM plane. The representation theory implies a natural splitting of the full symmetry group - the distinction between what is the background and what is the excitation is accomplished in the choice of the subgroup and representations used to construct the operator. Connecting the descriptions utilised in obtaining these results is expected to allow the construction of operators dual to general open string con gurations on the class of backgrounds considered. / GR 2016
77

Zeros de combinações lineares de polinômios /

Mello, Mirela Vanina de. January 2012 (has links)
Orientador: Dimitar Kolev Dimitrov / Coorientador: Cleonice Fátima Braccialli / Banca: Roberto Andreani / Banca: Luis Gustavo Nonato / Banca: Eliana Xavier Linhares de Andrade / Banca: German Jesus Lozada Cruz / Resumo: Neste trabalho, estudamos propriedades dos zeros de polinômi os ortogonais do tipo Sobolev . Provam os resultados sobre entrelaçamento, monotonicidade e assintótica. Fornecemos, também , condições s necessárias e/ou suficientes para os zeros dos polinômios {Sn}n≥0, gerados pela fórmula Sn(x) = Pn(x) + an−1Pn−1(x), ou Sn(x) −bn−1Sn−1(x) = Pn(x), on d e {Pn}n≥0 é um a sequência de polinômios ortogonais, ser em todos reais / Abstract: We study various properti s of the zeros of Sobolev typ e orthogonal polynomials. Results on interacing, monotonicity and asymptotic are proved . We also provide general necessary and/or sufficient con ditions in order to the zeros of the polynomials {Sn}n≥0, generated by the formulae Sn(x) = Pn(x) + an−1Pn−1(x), or Sn(x) −bn−1Sn−1(x) = Pn(x), where {Pn}n≥0 is a sequence of orthogon al polynomials, are all real / Doutor
78

QoS-aware adaptive call admission control in multiuser OFDM wireless network.

January 2008 (has links)
Yu, Xi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 46-49). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / Chapter Chapter 1 --- Introduction and Background --- p.1 / Chapter 1.1 --- Background --- p.3 / Chapter 1.1.1 --- Brief Review of CAC --- p.3 / Chapter 1.1.2 --- Dynamic Sub-carrier Allocation in Multi-user OFDM Wireless Network --- p.6 / Chapter 1.2 --- Problem Statement --- p.11 / Chapter 1.3 --- The Organization of The Thesis --- p.12 / Chapter Chapter2 --- System Model and Call Admission Control Framework --- p.13 / Chapter 2.1 --- System setup --- p.13 / Chapter 2.2 --- The CAC Strategy Framework --- p.14 / Chapter Chapter 3 --- QoS-aware Adaptive Call Admission Control´ؤStep One: The QoS-Provisioning CAC --- p.18 / Chapter 3.1 --- Problem Formulation --- p.19 / Chapter 3.2 --- Optimal Condition Analysis --- p.21 / Chapter 3.3 --- Throughput Estimation Algorithm --- p.22 / Chapter 3.4 --- QoS-Provisioning CAC --- p.25 / Chapter 3.5 --- Performance Evaluation --- p.26 / Chapter Chapter 4 --- QoS-aware Adaptive Call Admission Control´ؤStep Two: Average Revenue Maximization CAC --- p.30 / Chapter 4.1 --- Semi-Markov Decision Process --- p.30 / Chapter 4.2 --- Investigation of Algorithms for SMDP --- p.34 / Chapter 4.3 --- The Average Revenue Maximum CAC --- p.37 / Chapter 4.4 --- Performance Evaluation --- p.40 / Chapter Chapter 5 --- Conclusion and Future Work --- p.44 / Bibliography --- p.46
79

Reduced Order Description of Experimental Two-Phase Pipe Flows: Characterization of Flow Structures and Dynamics via Proper Orthogonal Decomposition

Viggiano, Bianca Fontanin 11 August 2017 (has links)
Multiphase pipe flow is investigated using proper orthogonal decomposition for tomographic X-ray data, where holdup, cross-sectional phase distributions and phase interface characteristics within the pipe are obtained. Six cases of stratified and mixed flow with water content of 10%, 30% and 80% are investigated to gain insight into effects of velocity and proportion of water on the flow fields. Dispersed and slug flows are separately analyzed to consider the added interface complexity of the flow fields. These regimes are also highly applicable to industry operational flows. Instantaneous and fluctuating phase fractions of the four flow regime are analyzed and reduced order dynamical descriptions are generated. Stratified flow cases display coherent structures that highlight the liquid-liquid interface location while the mixed flow cases show minimal coherence of the eigenmodes. The dispersed flow displays coherent structures for the first few modes near the horizontal center of the pipe, representing the liquid-liquid interface location while the slug flow case shows coherent structures that correspond to the cyclical formation and break up of the slug in the first 5 modes. The low order descriptions of the high water content, stratified flow field indicates that main characteristics can be captured with minimal degrees of freedom. Reconstructions of the dispersed flow and slug flow cases indicate that dominant features are observed in the low order dynamical description utilizing less than 1% of the full order model. POD temporal coefficients a1, a2 and a3 show a high level of interdependence for the slug flow case. The coefficients also describe the phase fraction holdup as a function of time for both dispersed and slug flow. The second coefficient, a2, and the centerline holdup profile show a mean percent difference below 9% between the two curves. The mathematical description obtained from the decomposition will deepen the understanding of multiphase flow characteristics and is applicable to long distance multiphase transport pipelines, fluidized beds, hydroelectric power and nuclear processes to name a few.
80

Cross-layer design for OFDMA wireless system

Hui, Shui-wing, David. January 2007 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

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