Dissertations / Theses on the topic '2-D DCT'

This thesis describes the design of fast JPEG processing accelerators for a DSP processor.

Certain computation tasks are moved from the DSP processor to hardware accelerators. The accelerators are slave co processing machines and are controlled via a new instruction set. The clock cycle and power consumption is reduced by utilizing the custom built hardware. The hardware can perform the tasks in fewer clock cycles and several tasks can run in parallel. This will reduce the total number of clock cycles needed.

First a decoder and an encoder were implemented in DSP assembler. The cycle consumption of the parts was measured and from this the hardware/software partitioning was done. Behavioral models of the accelerators were then written in C++ and the assembly code was modified to work with the new hardware. Finally, the accelerators were implemented using Verilog.

Extension of the accelerator instructions was given following a custom design flow.

Práce se zabývá adaptivními filtry pro vizualizaci obrazů s vysokým rozlišením. V teoretické části je popsán princip činnosti konfokálního mikroskopu a matematicky korektně zaveden pojem digitální obraz. Pro zpracování obrazů je volen jak frekvenční přístup (s využitím 2-D a 3-D diskrétní Fourierovy transformace a frekvenčních filtrů), tak přístup pomocí digitální geometrie (s využitím adaptivní ekvalizace histogramu s adaptivním okolím). Dále jsou popsány potřebné úpravy pro práci s neideálními obrazy obsahujícími aditivní a impulzní šum. Závěr práce se věnuje prostorové rekonstrukci objektů na základě jejich optických řezů. Veškeré postupy a algoritmy jsou i prakticky zpracovány v softwaru, který byl vyvinut v rámci této práce.

Práce se zabývá adaptivními filtry pro vizualizaci obrazů s vysokým rozlišením. V teoretické části je popsán princip činnosti konfokálního mikroskopu a matematicky korektně zaveden pojem digitální obraz. Pro zpracování obrazů je volen jak frekvenční přístup (s využitím 2-D a 3-D diskrétní Fourierovy transformace a frekvenčních filtrů), tak přístup pomocí digitální geometrie (s využitím adaptivní ekvalizace histogramu s adaptivním okolím). Dále jsou popsány potřebné úpravy pro práci s neideálními obrazy obsahujícími aditivní a impulzní šum. Závěr práce se věnuje prostorové rekonstrukci objektů na základě jejich optických řezů. Veškeré postupy a algoritmy jsou i prakticky zpracovány v softwaru, který byl vyvinut v rámci této práce.

Cette thèse visait l’étude des micro-environnements géochimiques créés par la présence de l’herbier de Zostera noltei et de son réseau racinaire dans le Bassin d’Arcachon ainsi que ses effets 1) sur l’écologie des foraminifères benthiques, un groupe d’organismes présent en grand nombre dans les sédiments et dont l’influence sur les cycles biogéochimiques reste mal connue et 2) sur les espèces chimiques et les flux benthiques associés. Pour y répondre, une stratégie multidisciplinaire a été mise en place. L’étude écologique des foraminifères benthiques à l’échelle centimétrique, conduite dans des sédiments avec et sans végétation en février et juillet 2011, a montré la présence de trois espèces majeures aux métabolismes spécifiques. L’herbier de Zostera noltei semble influencer la densité et la profondeur de vie des espèces calcaires hétérotrophe (Ammonia tepida) et mixotrophe (Haynesina germanica), présentes près de la surface des sédiments. La troisième espèce (Eggerella scabra), au métabolisme anaérobie encore inconnu, est retrouvée sur au moins 7 cm de sédiment et semble préférer le carbone organique issu de la dégradation de l’herbier. En surface, la contribution des foraminifères à la reminéralisation aérobie a été évaluée à 7 % soit 5 fois plus que lors des études précédentes dans d’autres environnements marins. La présence de l’herbier influence également la géochimie du sédiment où des structures enrichies en fer dissous et appauvries en sulfure sont observables en 2D grâce aux gels DET-DGT développés ici. Le phosphate dissous semble dépendre de la demande des zostères et est observé à forte concentration uniquement sous forme de spots. Une tranche de sédiment, prélevée en vis-à-vis du gel DET-DGT visait la réalisation de cartes de la phase solide et de la densité des foraminifères. Bien que ce travail reste inachevé, des méthodes comme la micro-fluorescence et la micro-tomographie aux rayons X donnent des perspectives prometteuses. De nouvelles voies de recherches ont ainsi été ouvertes grâce à des méthodologies innovantes combinant physiologie, écologie et géochimie
This thesis aimed to study the geochemical microenvironments created by Zostera noltei meadows and its root system in Arcachon Basin and to evaluate the effect of these microenvironments 1) on living benthic foraminifera ecology, a group of organisms present in large densities in sediment which impact on marine biogeochemical cycles remain poorly known and 2) on the chemical species and associated benthic fluxes. To fulfill these objectives, a multidisciplinary strategy was developed. The study of benthic foraminiferal ecology at centimeter scale, conducted in sediments with or without vegetation in February and July 2011, has shown the presence of three major species with specific metabolisms. Zostera noltei meadows seem to influence the densities and the living depth of heterotrophic (Ammonia tepida) and mixotrophic (Haynesina germanica) calcareous species, present in the sediment surface. The third species (Eggerella Scabra), which anaerobic metabolism is still to discover, is found throughout the sedimentary column and seems to prefer the organic matter coming from the degradation of the seagrass. In surface sediment, the contribution of these three species to aerobic remineralization was estimated at 7%, i.e. 5 times more than the maximum rates previously recorded in marine environments. The presence of the seagrass also influences geochemistry where enriched iron and depleted sulfide structures are observable in 2D thanks to DET-DGT gels developed here. Dissolved phosphorus depended on seagrass uptake and was highly concentrated only as scattered spots. A slice of sediment, taken face to face with the DET-DGT gel, was also conducted during this study aiming to map the solid phase and foraminiferal density. Despite this work is still in progress, methods such as X-ray microfluorescence and microtomography showed promising perspectives. New research pathways have been opened through technological developments and innovative approaches combining physiology, ecology, and geochemistry

Dans le cadre de la recherche de vecteurs d'énergie “propres”, le borazane et ses dérivés amine-boranes sont devenus des candidats intéressants en tant que matériaux de stockage de l'hydrogène en raison de leur pourcentage massique relativement élevé en hydrogène (19,6% pour borazane) et de la réversibilité potentielle de la réaction de déshydrogénation. Pour des applications réelles, le contrôle des réactions se produisant à la température ambiante est fondamental. Dans ce contexte, la compréhension du processus de la déshydrogénation/déshydrocouplage catalytique de l'amine-borane apparaît comme un élément important. Dans cette thèse, les catalyseurs de types métallocènes du Groupe IV (Cp2M, M = Ti, Zr et Hf) sont étudiés en détail. Le déshydrocouplage de HMe2N·BH3 catalysé par le titanocène a été étudié à la fois expérimentalement et théoriquement mais aucun accord n'avait été atteint auparavant. Dans ce travail, les caractérisations systématiques des interactions 3-centre 2-électron M···H-B impliquées dans les intermédiaires réactionnels ont été réalisées avec des approches topologiques QTAIM et ELF. Par la suite, des mécanismes réactionnels détaillés ont été étudiés. Les résultats théoriques ont démontré que la méthode DFT corrigée avec la dispersion (DFT-D) étaient nécessaire et suffisantes pour une description énergétique correcte des chemins réactionnels. Mon travail a également permis l'identification d'un complexe de van der Waals jouant un rôle clé dans le mécanisme réactionnel en accord avec les observations expérimentales
With the increasing demand of clean energy carriers, ammonia borane and its related amine-borane compounds have emerged as attractive candidates for hydrogen storage materials due to their relatively high weight percentage of available hydrogen (19.6% for ammonia borane) as well as the potential reversibility for the hydrogen release reactions. Actual applications would benefit from controlled reactions occurring close to room-temperature. In this context, catalytic dehydrogenation/dehydrocoupling of amine-borane appears as a promising solution. In this thesis the Group IV metallocene (Cp2M, M = Ti, Zr and Hf) are mainly discussed. The dehydrocoupling of HMe2N·BH3 catalyzed by titanocene was investigated both experimentally and theoretically but no agreement were reached. In this work, systematic characterization of M···H-B 3-center 2-electron interactions involved in reaction intermediates were carried out with QTAIM and ELF topological approaches. Afterwards, detailed mechanisms were further studied. Computational results have demonstrated that the dispersion corrected DFT (DFT-D) method was indispensable for a correct enegetic prediction for reaction pathways. The identification of a van der Waals complexe also plays a central role for a reaction mechanism with good agreement with experimental observations

Dans cette thèse, nous avons étudié les propriétés de deux matériaux 2D constitués de germanium : le germanène, l'équivalent du graphène, et un empilement multicouche de germanane à terminaison méthyle. En raison d’une structure atomique gauchie et d’un couplage spin orbite important, ces matériaux se démarquent du graphène et du graphite. Bien que très étudiés théoriquement, leurs propriétés physiques restent encore peu caractérisées. Dans le cas du germanène, l’étude de ce matériau a été réalisée en déposant du germanium sur une surface d’aluminium (111) sous ultravide. Pour des températures de croissance relativement basses, autour de 100°C, le germanène est épitaxié avec deux structures : la phase (3x3) et la phase (√7x√7). La microscopie à effet tunnel a été utilisée pour approfondir notre connaissance de ces phases. Dans un premier temps nous nous sommes intéressés aux propriétés électroniques. Des mesures spectroscopiques par microscopie à effet tunnel ont été réalisées à des températures de 77K et 5K. Elles n’ont malheureusement pas permis de conclure quant à la véritable nature du germanène en raison du fort couplage électronique de ce matériau avec la surface d’aluminium. Toutefois, au travers d’une diversité inattendue de spectres, cette analyse a révélé la faible adhésion du germanène à la surface Al(111), ce qui conduit à une contamination fréquente de l’apex de la pointe du microscope par les atomes de la surface. Parallèlement aux mesures spectroscopiques, la croissance de feuillets aux dimensions réduites a permis d’étudier la structure des bords des feuillets. Les observations par microscopie à effet tunnel montrent que ces feuillets croissent dans le plan des terrasses atomiques d’aluminium. Leurs bords présentent généralement un contraste plus clair que le reste du feuillet. Pour mieux comprendre ce changement de contraste, des calculs ab-initio basés sur la théorie de la fonctionnelle de la densité (DFT), ont été développés. Ils ont montré le rôle clé des atomes d’aluminium dans la formation des bords possédant quelque soit la structure zigzag ou « armchair ». A l’inverse du germanène mono-feuillet qui requiert une épitaxie, des cristaux de germanane peuvent être synthétisé par voie chimique, ce qui assure un découplage électronique du matériau avec son environnement. Nous avons réalisé une analyse multiphysique de tels cristaux passivés par des groupements méthyles, qui révèlent deux types de cristaux. Les plus gros, autour de 10 m de dimension latérale, sont polycristallins, recèlent des molécules intercalées entre les feuillets ou possèdent des surfaces oxydés et se chargent sous irradiation électronique en raison de la présence d’isopropanol à l’interface avec le substrat hôte. Les plus petits, identifiés comme les plus purs, sont les plus enclins à être caractérises par des mesures de transport à quatre pointes en ultravide. Ces mesures ont montré un transport de trous, qui se produit en volume. Ce résultat inattendu pour un matériau lamellaire suggère la présence de défauts et d’imperfection dans le plan des feuillets qui appellent à un meilleur contrôle de la synthèse des cristaux pour rendre possible l’étude des propriétés physiques fondamentales de ces cristaux
In this thesis, we have studied the properties of two 2D materials made of germanium: germanene, the equivalent of graphene, and a multilayer stack of germanene terminated with methyl groups. Due to a buckled atomic structure and a strong spin orbit coupling, these materials stand out from graphene and graphite. Although much studied in theory, their physical properties remain little characterized. In the case of germanene, the study of this material was carried out by depositing germanium on an aluminum (111) surface in ultra-high vacuum. For relatively low temperatures, around 100° C, the growth of germanene is epitaxial with two structures: the (3x3) reconstruction and the (√7x√7) reconstruction. Scanning tunneling microscopy has been used to deepen our knowledge of these phases. First of all, we were interested in the electronic properties. Spectroscopic measurements were carried out at temperatures of 77K and 5K. Unfortunately, they did not reveal the true nature of germanene due to the strong electronic coupling of this material with the aluminum surface.Throughout an unexpected diversity of spectra, this analysis showed the weak adhesion of germanene to the Al(111) surface, which leads to frequent contamination of the apex of the tip of the microscope by atoms of the area. In addition to spectroscopic measurements, the growth of small-sized sheets enabled the study of the edge structure. Observations by tunneling microscopy showed that these sheets grow in the plane of the aluminum atomic terraces. Their edges generally present a clearer contrast than the rest of the sheet. To better understand this change of contrast, ab-initio calculations based on density functional theory (DFT) have been performed. They showed the key role of aluminum atoms in the formation of edges, with both zigzag or armchair structures. Unlike single-sheet germanene which requires an epitaxial growth, germanane crystals can be chemically synthesized, which ensures the electronic decoupling of the material from its environment. We carried out a multi-physics analysis of such crystals passivated by methyl groups, which revealed two types of crystals. The largest, around 10 micrometres in lateral dimension, are polycrystalline, contain water molecules intercalated between the layers or have oxidized surfaces and become charged under electron irradiation due to the presence of isopropanol at the interface with the host substrate. The smallest, identified as the purest, are the most prone to being characterized by ultra-high vacuum four-probe transport measurements. These measurements showed a transport of holes, which occurs in the volume of the microstructure. This unexpected bulk transport for a lamellar material suggests the presence of defects and imperfection in the plane of the layers, which calls for a better control of the synthesis of these crystals

Le greffage chimique et l'assemblage supramoléculaire de mol écules organiques sur les semiconducteurs est une approche intéressante pour la fabrication de dispositifs dans le domaine de l'électronique moléculaire. En particulier, la surface de silicium orient ée (001), reconstruite 2x 1, peut être utilisée comme un gabarit pour greffer des mol écules organiques de façon organisée dans des conditions de ultra haut vide. Cependant, les molécules bifonctionnelles conduisent à des géométries d'adsorption multiples, qu'il est nécessaire de comprendre a fin de pouvoir les contrôler. Les spectroscopies de photo émission et d'absorption X, associées a des calculs DFT de structures électroniques, ont permis de déterminer les modes d'adsorption de l'ammoniac, de l'éthylènediamine, du 1-4 diaminobutane et du N,N,N',N' tétraméthyl éthylènediamine sur la surface Si(001)-2x 1. Dans ce dernier cas, une évolution des modes d'adsorption, en fonction de la dose d'exposition et d'irradiation a également pu être mise en évidence.

碩士
國立臺灣大學
電機工程學系
85
The discrete cosine transform (DCT) has been recognized as one of the keytechniques in image and video compression standards. Recently, these standardsare applied to the portable devices which are battery-powered. Thus, in oder toprolong the using time between recharging, it is imperative to develop a DCTmodule which consumes less power. In this thesis, a low power 8$\times$8 2-D DCT CMOS VLSI design based on direct 2-D approach is implemented. The direct 2-D method for the DCTreduces computational complexity by taking advantage of the attribute of complexnumber. According to this algorithm, a parallel distributed arithmetic (DA) architecture at reduced supply voltage is derived. Moreover, in the real circuit implementation of the chip, a hybrid-architecture adder of low power consumption is proposed. Also, a power-saving ROM and a low voltage two-port SRAM with sequentialaccess are designed. Both the adder and the memories are the main modules of the 2-D DCT chip to approach low power. In addition to these modules, some peripheralcircuits such as registers are also under the low power considerations. After that, the resultant 2-D DCT chip is realized by 0.6 $\mu$m single-poly double-metal techlnology. The goal of its throughput is set at 200 MHz in order to meet the requirement of the real-time HDTV signal processing. The power simulated by module is 228mW. Finally, the chip can run at 133MHz maximumly and consumes 138mW at 100MHz.

碩士
大同工學院
電機工程研究所
87
This thesis discusses the design of a combined DCT/IDCT CMOS integrated circuit for general video application. We know that the discrete cosine transform is widely used in several international standards, in this thesis, we use a low-complexity, and high-performance architecture to realize a DCT/IDCT chip. Beside, we also use some technique (tree structure) to improve the chip performance. Based on TSMC SPTM 0.6μm CMOS technology and COMPASS 0.6μm cell library, our DCT chip is implemented. It integrates about 120k transistors, and die size occupies a silicon area of 5415μm x 5495μm, and simulation results show that the clock rate can be up to above 85MHz that conforms our requirement.

碩士
大同大學
電機工程學系(所)
96
The digit compress technology is concerned by people extremely. The 2-D DCT and IDCT are widely used and the most effective compression technology in image compressing. There are also a lot of new algorithms being proposed all the time, but most structure application will spend too much cost. This paper takes the short time to market and low cost as the direction in design. We make the design to be an DCT/IDCT IP under the consideration of the area and speed of the chip. Though 2-D DCT/IDCT roughly are divided into row-column decomposition (RCD) and not row-column decomposition (NRCD). NRCD is more efficient than RCD, but it is relatively too complex for hardware to be implemented. So the design structure of this thesis also uses RCD as usual. And in order to get higher throughput, it uses two 1-D DCT/IDCT circuit units to do parallel operation. It also uses the improved shift-and-add multiplication logic to balance each multiplication path and save hardware resource. Combined with the concept of pipeline, the design can deal with input data continually. Finally, we can ensure the design reaching the requirements with the function and timing checking. Then we enforce placement and routing steps of back-end flow to finish the physical layout and make physical verifications to guarantee that the chip can be tape-outed.

碩士
中華大學
電機工程研究所
86
Discrete Cosine Transform (DCT) has been commonly adopted in many transformation application such as image, video, and facsimile. The discrete transform (DCT) has been recognized as one of the standard techniques in image compression. Therefore, a core processor that rapidly compputes DCT/IDCT has become a key comonent-in image compression in VLSI implementation. 　　This paper describes ka 100-MHz two-dimensional DCT/IDCT core processor, whice is applicable to the real-time processigng of H.263 signals. Furthermore, mean values of errors generated in the core were minimezed to enhance the computational accuracy with the word-length constraints. Consequently,it features the fast operating speed under the low area with ist sufficient accuracy satisfying the specifications in CCITT recommendation H.263.

碩士
逢甲大學
自動控制工程學系
89
There are many efficient VLSI architectures of 2-D DCT and 2-D IDCT for area and processing speed points of view. However, most of them spend much cost for using in a real-time digital video codec system. The aim of our research work was to develop an area efficient and low complexity VLSI architecture of 2-D DCT and 2-D IDCT for real-time digital low bit-rate video codec system. Hardware cost and performance of this architecture are main key point. It is based on the row-column decomposition technique. This architecture would be shown that a single 1-D DCT/IDCT could take role of 2-D DCT and 2-D IDCT. It can be achieved through precise timing scheduled. Intuitively, three 1-D DCT/IDCT and a matrix transposition could be saved as compared to the conventional architectures which usually use two one-dimensional transforms and transposition memory. To reduce its processing time, the proposed architecture used 3-bit serial distributed arithmetic, parallel and pipelined method. We simulated the finite wordlength of the proposed 2-D DCT/IDCT algorithm with C language. Then, based on TSMC 0.35um process technique, Galax! 0.35um cell library is used to implement the 2-D DCT/IDCT architecture. In proposed architecture, 11895 gates were consumed roughly for 45 MHz operating clock. As a result, this architecture can be characterized to maximize the utilization of the hardware resources. It also can be applied to the ASIC chips for real-time digital low bit-rate video codec system and multimedia services especially requiring low cost and low hardware complexity.

The discrete cosine transform (DCT) is widely used in the area of signal and image processing. The 2-D DCT has been used in image compression and become part of image and video standards. The 2-D DCT computation involves a large amount of data. Many applications require the systems to be in small volume and operate in real-time. Designing such a system for 2-D DCT is a challenging task. In this thesis, a new recursive algorithm and two types of circuit architectures are presented for the computation of the 2-D DCT. The new algorithm permits to compute the 2-D DCT by a simple procedure of the 1-D recursive calculations involving only cosine coefficients. A recursive kernel for the proposed algorithm contains a small number of operations. Also, it requires a smaller number of pre-computed data compared to many of existing algorithms in the same category. The kernel can be easily implemented in a simple circuit block with a short critical delay path. In order to evaluate the performance improvement resulting from the new algorithm, an architecture for the 2-D DCT designed by direct mapping from the computation structure of the proposed algorithm has been implemented on an FPGA board. The results show that the reduction of the hardware consumption can easily reach 25% and the clock frequency can increase 17% compared to a system implementing a recently reported 2-D DCT recursive algorithm. For a further reduction of the hardware, another architecture has been proposed for the same 2-D DCT computation. Using one recursive computation block to perform different functions in each clock cycle, this architecture needs only approximately one half of the hardware that is required in the first architecture, which has been confirmed by an FPGA implementation

碩士
淡江大學
電機工程學系
84
The discrete cosine transform (DCT) has been widely used as the core of digital image and video signal compression. However, its computation is so intensive and is of great necessity to meet the requirement of high speed. In this thesis, a new architecture for VLSI implementation of 2-D DCT chip has been developed. This architecture contains the following features : (1) using the programming logic array (PLA) to replace multipliers, (2) overlappedrow-columnoperations and pipelined structure to reduce the totalcomputation time, (3) highly modular and regular structure for efficient VLSI implementation. This chip is designed for real-time digital video data and the processing data rate is more than 50 MHz. It performs more than 800 million multiplication and accumulation operations per second. The VLSI chip will be implemented by TSMC's 0.8 SPDM CMOS process, and the cell library is provided by ITRI CCL. The hier achical modules of this chip is designed by Verilog HDL and synthsized by Synopsys synthsis tools, and the circuitlayout is using Cadence CAD tools for automatically place and route.

碩士
中華大學
電機工程學系碩士班
94
Abstract With the rapid growth of modern communication applications and computer technologies, image compression is increasingly in demand. From the compression point of view, transform coding is superior to linear predication coding. Walsh-Hadamard transform is the simplest one, in which the computations involved in the kernel matrix are only additions and subtractions. As cosine transform approximates to the optimal Karhunen-Loeve transform, which is however much more complicated in practice, discrete cosine transform (DCT) has been widely used in the image compression task. Moreover, DCT is adopted by the JPEG standard. Two-dimensional discrete cosine transform (DCT) and inverse discrete cosine transform (IDCT) have been widely used in many image processing systems. In this paper, efficient architecture with parallel and pipelined structures are proposed to implement 8x8 DCT and IDCT processors. In which, dual-bank of SRAM (128 words) and single bank of SRAM (64 words),the coefficient ROM (6 words) is utilized for saving the memory space. The kernel arithmetic unit, i.e. multiplier, which is demanding in the implementation of DCT and IDCT processors, has been replaced by simple adders and shifters based on the double rotation CORDIC algorithm. The proposed architectures for 2-D DCT and IDCT processor not only simplify hardware but also reduce the power consumption with high performances. The proposed parallel-pipelined architecture for 2-D DCT and IDCT processors have been written in Verilog® and synthesized by TSMC 0.18μm 1P6M CMOS cell libraries. Finally, the layout of the design is generated automatically by the Astro Layout Tools in a 0.18μm 1P6M CMOS technology. The core sizes and power consumptions can be obtained from the reports of Synopsys® design analyzer and PrimPower®, respectively.

Title: Structure analysis of some transition metal silicides using X-ray diffraction and dynamical refinement against electron diffraction data Author: Cinthia Antunes Corrˆea Department: Physics of Materials Supervisor: prof. RNDr. Miloš Janeček, CSc., Department of Physics of Materials Abstract: This thesis presents the crystal structure analysis of several transition metal silicides. The crystal structures were studied primarily by precession electron diffraction tomography (PEDT) employing the dynamical refinement, a method recently developed for accurate crystal structure refinement of electron diffraction data. The optimal values of the parameters of the method were proposed based on the comparison between the dynamical refinement of PEDT data and a high- quality reference structure. We present the results of the comparison using a Ni2Si nanowire with the diameter of 15 nm. The average atomic distance between the model obtained by the dynamical refinement on PEDT data and the one by single crystal X-ray diffraction was 0.006 ˚A. Knowing the accuracy and limitations of the method, the crystal structure of Ni3Si2 was redetermined on a nanowire with 35 nm of diameter. The model obtained had an average error in the atomic posi- tions of 0.006 ˚A. These results show that the accuracy achieved by the dynamical...