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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.
181

Investigation of LDPC code in DVB-S2

Ge, Hanxiao January 2012 (has links)
As one of the most powerful error-correcting codes, Low-density parity check codes are widely used in digital communications. Because of the performance of LDPC codes are capable to close the shannon limited extraordinarily, LDPC codes are to be used in the new Digital Video Broadcast-Satellite-Second Generation(DVB-S2) and it is the first time that LDPC codes are included in the broadcast standard in 2003. In this thesis, a restructured parity-check matrices which can be divided into sub-matrices for LDPC code in DVB-S2 is provided. Corresponded to this restructured parity-check matrix, a reconstructed decoding table is invented. The encoding table of DVB-S2 standard only could obtain the unknown check nodes from known variable nodes, while the decoding table this thesis provided could obtain the unknown variable nodes from known check nodes what is exactly the Layered-massage passing algorithm needed. Layered-message passing algorithm which also known as "Turbo-decoding message passing" is used to reduce the decoding iterations and memory storage for messages. The thesis also investigate Bp algorithm, lambda-min algorithm, Min-sum algorithm and SISO-s algorithm, meanwhile, simulation results of these algorithms and schedules are also presented.
182

Characteristics and origins of secondary chloritic minerals in the Tertiary basaltic rocks from Taiwan.

Ho, You-Hua 26 July 2010 (has links)
Chlorite and corrensite are very common secondary minerals in very low-grade metamorphic or hydrothermally altered mafic rocks. Corrensite, although defined as a 1:1 regularly mixed-layered chlorite/smectite or chlorite/vermiculite, has been considered as a unique mineral phase and might thus be a potential index mineral for evaluating very low metamorphic grade. Many lenticular basaltic rocks, which are intercalated with unmetamorphosed to low-grade metamorphosed Tertiary sedimentary rocks, occur sporadically in the Western foothills and the Central Range in Taiwan. The lenticular basaltic rocks in the Western foothills (diagenetic zone) and the western flank of the Central Range (anchizone to epizone) were subjected to different degrees of hydrothermal alteration and/or metamorphism. However, only few occurrences of corrensite in these basaltic rocks were reported. In the present study, the occurrences and mixed-layering features of corrensite and coexisting chloritic minerals in the basaltic rocks were characterized by utilizing optical microscopy, X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, and transmission electron microscopy (TEM). The results showed that most of these basaltic rocks contain abundant chloritic minerals occurring as replacements of mafic minerals or interstitial glass, or as vein- or vesicle-filling materials. The chloritic minerals include smectite, corrensite, chlorite, mixed-layered chlorite/smectite, or mixed-layered chlorite/corrensite. The compositions of chlorite, corrensite, and smectite are distinctive in terms of their Si/Al ratios, interlayer cations, and total cation numbers. Corrensite, chlorite, and mixed-layered chlorite/corrensite are common secondary mineral assemblages in the anchizone basaltic rocks, whereas only discrete chlorite occur in the epizone. The basaltic rocks in the diagenetic zone contain different assemblages, such as smectite only, chlorite + smectite + mixed-layered chlorite/smectite + mixed-layered chlorite/corrensite, or chlorite + corrensite + mixed-layered chlorite/corrensite. These different assemblages of chloritic minerals and other secondary mineral assemblages might reflect different stages of hydrothermal alteration. Corrensite was positively identified with TEM lattice-fringe imaging in the diagenetic rocks collected from Nangang, Poneikeng, Shanzijiao, Nanshihjiao, Hsiungkong, Shihsiouping, Fusing, and Northern Shihmen Reservoir areas, and in the studied anchizone rocks from Junghua, Kaopo and Baolai areas. The disappearance of corrensite clearly marks the boundary between the anchizone and epizone basaltic rocks. Corrensite, as a chemically and structurally unique mineral phase, is therefore a potential index mineral in very low-grade metamorphic rocks.
183

Layered Video Multicast Using Fractional Frequency Reuse over Wireless Relay Networks

Chen, Ying-Tsuen 27 September 2011 (has links)
Multimedia services over wireless networks are getting popular. With multicast many mobile stations can join the same video multicast group and share the same radio resource to increase frequency utilization efficiently. However users may locate at different positions so as to suffer different path loss, interference and receive different signal to interference and noise ratio (SINR). Users at the cell-edge receiving lower SINR may degrade the multicast efficiency. In this thesis we propose four schemes considering fractional frequency reuse (FFR) over relay networks to reuse frequency in multi-cells. With fractional frequency reuse, users close to the base station (BS) have more resources to improve the total frequency utilization. A resource allocation scheme is also proposed to efficiently allocate wireless resources. Compared to the conventional relay scheme, the proposed schemes can provide more than 10% video layers for all users and give better video quality for users near BS.
184

Characterization of thermo-mechanical and long-term behaviors of multi-layered composite materials

Nair, Aravind R. 02 June 2009 (has links)
This study presents characterization of thermo-mechanical viscoelastic and long-term behaviors of thick-section multi-layered fiber reinforced polymer composite materials. The studied multi-layered systems belong to a class of thermo-rheologically complex materials, in which both stress and temperature affect the time-dependent material response. The multi-layered composites consist of alternating layers of unidirectional fiber (roving) and randomly oriented continuous filament mat. Isothermal creep-recovery tests at various stresses and temperatures are performed on E-glass/vinylester and Eglass/ polyester off-axis specimens. Analytical representation of a nonlinear single integral equation is applied to model the thermo-mechanical viscoelastic responses for each off-axis specimen. Long-term material behaviors are then obtained through vertical and horizontal time shifting using analytical and graphical shifting procedures. Linear extrapolation of transient creep compliance is used to extend the material responses for longer times. The extended long-term creep strains of the uniaxial E-glass/vinylester specimens are verified with the long-term experimental data of Scott and Zureick (1998). A sensitivity analyses is then conducted to examine the impact of error in material parameter characterizations to the overall long-term material behaviors. Finally, the calibrated long-term material parameters are used to study the long-term behavior of multi-layered composite structures. For this purpose, an integrated micromechanical material and finite element structural analyses is employed. Previously developed viscoelastic micromodels of multi-layered composites are used to generate the effective nonlinear viscoelastic responses of the studied composite systems and then implemented as a material subroutine in Abaqus finite element code. Several long-term composite structures are analyzed, that is; I-shaped columns and flat panels under axial compression, and a sandwich beam under the point bending and transmission tower under lateral forces. It is shown that the integrated micromechanical-finite element model is capable of predicting the long-term behavior of the multilayered composite structures.
185

Automatic Assignment of Protein Function with Supervised Classifiers

Jung, Jae 16 January 2010 (has links)
High-throughput genome sequencing and sequence analysis technologies have created the need for automated annotation and analysis of large sets of genes. The Gene Ontology (GO) provides a common controlled vocabulary for describing gene function. However, the process for annotating proteins with GO terms is usually through a tedious manual curation process by trained professional annotators. With the wealth of genomic data that are now available, there is a need for accurate auto- mated annotation methods. The overall objective of my research is to improve our ability to automatically an- notate proteins with GO terms. The first method, Automatic Annotation of Protein Functional Class (AAPFC), employs protein functional domains as features and learns independent Support Vector Machine classifiers for each GO term. This approach relies only on protein functional domains as features, and demonstrates that statistical pattern recognition can outperform expert curated mapping of protein functional domain features to protein functions. The second method Predict of Gene Ontology (PoGO) describes a meta-classification method that integrates multiple heterogeneous data sources. This method leads to improved performance than the protein domain method can achieve alone. Apart from these two methods, several systems have been developed that employ pattern recognition to assign gene function using a variety of features, such as the sequence similarity, presence of protein functional domains and gene expression patterns. Most of these approaches have not considered the hierarchical relationships among the terms in the form of a directed acyclic graph (DAG). The DAG represents the functional relationships between the GO terms, thus it should be an important component of an automated annotation system. I describe a Bayesian network used as a multi-layered classifier that incorporates the relationships among GO terms found in the GO DAG. I also describe an inference algorithm for quickly assigning GO terms to unlabeled proteins. A comparative analysis of the method to other previously described annotation systems shows that the method provides improved annotation accuracy when the performance of individual GO terms are compared. More importantly, this method enables the classification of significantly more GO terms to more proteins than was previously possible.
186

Full-wave Surface Integral Equation Method for Electromagnetic-circuit Simulation of Three-dimensional Interconnects in Layered Media

Karsilayan, Nur 2010 May 1900 (has links)
A new full-wave surface impedance integral equation method is presented for three-dimensional arbitrary-shaped interconnect parasitic extraction in layered media. Various new ways of applying voltage and current excitations for electromagnetic-circuit simulation are introduced. A new algorithm is proposed for matrix formation of electromagnetic-circuit simulation, low frequency solution and layered media so that it can be easily integrated to a Rao-Wilton-Glisson based method of moment code. Two mixed potential integral equation forms of the electric field integral equation are adapted along with the Michalski-Mosig formulations for layered kernels to model electromagnetic interactions of interconnects in layered media over a conducting substrate. The layered kernels are computed directly for controllable accuracy. The proposed methods are validated against existing methods for both electromagnetic and electromagnetic-circuit problems.
187

Determination Of Presentation Principles For Multi-layered Historical Towns Based On Cultural Significance Case Study: Tarsus

Aykac, Pinar 01 February 2003 (has links) (PDF)
The main subject of the thesis is multi-layered historical towns which are formed as a result of collective creation process and continuous inhabitancy that new buildings, edifices and open areas superimpose in time forming a specific character which can be defined as multi-layeredness. Considering the specific character of multi-layered towns, the principles for the presentation of historical stratification is the foremost objective of the thesis. The thesis focuses on &amp / #8216 / presentation principles based on cultural significance of multi-layered historical towns so as to conserve, sustain and present their specific character as an integral part of the conservation process. Therefore, the aim of this thesis is to determine presentation principles for multilayered historical towns in order to reveal and conserve their historical stratification by assessing the historical continuities, interruptions and transformations based on the cultural significance of multi-layeredness. Focusing on this aim, the thesis is structured in two parts as the identification of presentation principles for multi-layered historical towns, discussing the information groups effecting the determination of cultural significance followed by the implementation of these principles on a concrete example as the case study. Subsequently, a proposal for the presentation principles guiding the design stages together with the identification of information groups for the determination of cultural significance is apprehended for the case study. The case study selected in the thesis for the implementation of the proposed principles is Tarsus which is a multi-layered historical town in Turkey having presentation potential for historical stratification. To conclude, depending on the cultural significance specific to multi-layered historical towns, presentation is a way for the understanding and dissemination of these significances. The presentation principles set in this thesis can be regarded as a part of the conservation planning that has to be integrated to the existing process and it is possible to state that these principles are essential for the conservation and sustainability of multi-layered character of historical towns.
188

Optical And Electrical Transport Properties Of Some Quaternarythallium Dichalcogenides

Guler, Ipek 01 June 2011 (has links) (PDF)
In this thesis, in order to study the structural, optical and electrical transport properties of Tl2In2S3Se, TlInSeS and Tl2In2SSe3 crystals, X-ray diffraction (XRD), energy dispersive spectroscopic analysis (EDSA), transmission, reflection, photoluminescence (PL), thermally stimulated current (TSC) and photoconductivity decay (PC) measurements were carried out. Lattice parameters and atomic composition of these crystals were determined from XRD and EDSA experiments, respectively. By the help of transmission and reflection experiments, the room temperature absorption data were analyzed and it was revealed the coexistence of indirect and direct band gap energies of the studied crystals. Moreover, the refractive index dispersion parameters - oscillator energies, dispersion energies, oscillator strengths, oscillator wavelengths and zero-frequency refractive indexes were determined. Temperature-dependent transmission measurements made it possible to find the rate of change of indirect band gaps with temperature, absolute zero values of the band gap energies and Debye temperatures of these crystals. From the analysis of the transmission and reflection measurements, it was established that, there is a decrease in the values of indirect and direct band gaps energies and an increase in zero-frequency refractive indexes with increasing of selenium content. PL measurements were carried out to obtain the detailed information about recombination levels in crystals studied. The behavior of PL spectra were investigated as a function of laser excitation intensity and temperature. The variation of the spectra with laser excitation intensity and temperature suggested that the observed emission bands in these crystals were due to the donor-acceptor pair recombination. TSC measurements were carried out with various heating rates at different illumination temperatures to obtain information about trap levels in these crystals. The mean activation energies, attempt-to-escape frequencies, concentrations and capture cross sections of the traps were determined as a result of TSC spectra analysis. The analysis of experimental TSC curves registered at different light illumination temperatures revealed the exponential trap distribution in the studied crystals. From the analysis of PC measurements, carrier lifetimes were obtained.
189

Assessing The Integration Of Historical Stratification With The Current Context In Multi-layered Towns. Case Study: Amasya

Etyemez, Leyla 01 September 2011 (has links) (PDF)
The major subject of this study is the multi-layered historical towns which are the outcome of continuous inhabitation process. This continuous inhabitation is reflected in the current town by the physical remains belonging to different periods. These remaining elements of the past periods can be conserved, as long as they become an integral part of the current urban context. Thus, sustaining the multi-layeredness requires sustaining the integration of the remaining elements of the former periods with the current context. Thereupon, the main aim of the thesis becomes to develop a method for assessing the integration of historical stratification with the current town in accordance with the physical, visual, functional, social and managerial aspects. Consequently, the main concerns of this thesis are understanding and assessing the historical stratification together with its integration with the current town. This makes possible to expose the factors of disintegration which can provide a basis for defining the strategies and tools for their reintegration with the current urban context. With regard to this aim, the thesis is composed of two parts. In the first part a method for the assessment of the integration of historical stratification with the current context is proposed by considering various factors affecting the integration. It also covers a preliminary discussions on re-integration tools and strategies. In the second part, the proposed method is applied on the case of Amasya which is a multi-layered historical Anatolian town in Turkey. Following this, a preliminary discussion on possible reintegration strategies and tools for the case of Amasya is carried on. The thesis concludes with a general evaluation of the method developed in this thesis for the assessment of the integration of the historical stratification with the current town based on the outcomes of the implementation of the proposed method on the case of Amasya . The method developed in this thesis can be regarded as an initial step for revealing the factors effecting integration of the remains of past periods forming up the historical stratification in multi-layered towns, which can lead to the future possible re-integration strategies and tools in order to provide their sustainable conservation.
190

Fabrication of L12-CrPt3 Alloy Films Using Rapid Thermal Annealing for Planar Bit Patterned Media

Tsunashima, Shigeru, Iwata, Satoshi, Yamauchi, Yukihiro, Oshima, Daiki, Kato, Takeshi 06 1900 (has links)
No description available.

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