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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.
1

Optimisation des transferts de données sur systèmes multiprocesseurs sur puce / Optimizing Data Transfers for Multiprocessor Systems on Chips

Saidi, Selma 24 October 2012 (has links)
Les systèmes multiprocesseurs sur puce, tel que le processeur CELL ou plus récemment Platform 2012, sont des architectures multicœurs hétérogènes constitués d'un processeur host et d'une fabric de calcul qui consiste en plusieurs petits cœurs dont le rôle est d'agir comme un accélérateur programmable. Les parties parallélisable d'une application, qui initialement est supposé etre executé par le host, et dont le calcul est intensif sont envoyés a la fabric multicœurs pour être exécutés. Ces applications sont en général des applications qui manipulent des tableaux trés larges de données, ces données sont stockées dans une memoire distante hors puce (off-chip memory) dont l 'accès est 100 fois plus lent que l 'accès par un cœur a une mémoire locale. Accéder ces données dans la mémoire off-chip devient donc un problème majeur pour les performances. une characteristiques principale de ces plateformes est une mémoire local géré par le software, au lieu d un mechanisme de cache, tel que les mouvements de données dans la hiérarchie mémoire sont explicitement gérés par le software. Dans cette thèse, l 'objectif est d'optimiser ces transfert de données dans le but de reduire/cacher la latence de la mémoire off-chip . / Multiprocessor system on chip (MPSoC) such as the CELL processor or the more recent Platform2012 are heterogeneous multi-core architectures, with a powerful host processor and a computation fabric, consisting of several smaller cores, whose intended role is to act as a general purpose programmable accelerator. Therefore computation-intensive (and parallelizable) parts of the application initially intended to be executed by the host processor are offloaded to the multi-cores for execution. These parts of the application are often data intensive, operating on large arrays of data initially stored in a remote off-chip memory whose access time is about 100 times slower than that of the cores local memory. Accessing data in the off-chip memory becomes then a main bottleneck for performance. A major characteristic of these platforms is a software controlled local memory storage rather than a hidden cache mechanism where data movement in the memory hierarchy, typically performed using a DMA (Direct Memory Access) engine, are explicitely managed by the software. In this thesis, we attempt to optimize such data transfers in order to reduce/hide the off-chip memory latency.
2

Framework pro hardwarovou akceleraci 400Gb sítí / Framework for Hardware Acceleration of 400Gb Networks

Hummel, Václav January 2017 (has links)
The NetCOPE framework has proven itself as a viable framework for rapid development of hardware accelerated wire-speed network applications using Network Functions Virtualization (NFV). To meet the current and future requirements of such applications the NetCOPE platform has to catch up with upcoming 400 Gigabit Ethernet. Otherwise, it may become deprecated in following years. Catching up with 400 Gigabit Ethernet brings many challenges bringing necessity of completely different way of thinking. Multiple network packets have to be processed each clock cycle requiring a new concept of processing. Advanced memory management is used to ensure constant memory complexity with respect to the number of DMA channels without any impact on performance. Thanks to that, even more than 256 completely independent DMA channels are feasible with current technology. A lot of effort was made to create the framework as generic as possible allowing deployment of 400 Gigabit Ethernet and beyond. Emphasis is put on communication between the framework and host computer via PCI Express technology. Multiple Ethernet ports are also considered. The proposed system is prepared to be deployed on the family of COMBO cards, used as a reference platform.
3

Closed-loop control and data- recording of a modular-multilevel converter (MMC)

Su, Longgang January 2022 (has links)
Modular multilevel converters (MMCs) are the preferred converter solution in flexible ac transmission systems (FACTS) and high-voltage direct current (HVDC) applications. This is due to the high quality of the voltage and current signals, lower overall losses, and fewer problems with switching-related EMI. However, without an efficient and fast data recording system, the sampled data from current and voltage measurement boards can cause long latencies in the control system and make it difficult to analyze the operation of MMCs. In this thesis, a filed programmable gate array (FPGA)-based closed-loop control, and a high-speed data recording system is developed for a low-power singlephase MMC prototype. In the prototype, a data-transmission scheme based on the RS485 (TIA/EIA- 485) standard exists. This protocol offers a robust solution for transmitting data over noisy environments. A direct memory access (DMA) scheme is utilized to transmit sampled data from the programmable logic (PL) to the processing subsystem (PS) in the Zynq-7000 SOC. Moreover, an asymmetric multiprocessing (AMP) mechanism was implemented on the two processor cores in the PS. The first processor controls the power transmission to and from the power grid, and the second processor runs the ethernet application to transmit sampled data to the computer using MATLAB. For the closed-loop control of this MMC prototype, a phase-locked loop (PLL), a proportional resonant (PR) current controller, and an energy control loop for capacitor voltage balancing and control are implemented. The results showed that the output power of this single-phase MMC prototype is under control and each sub-module capacitor voltage is balanced and charged to the desired value. The sampled data can be recorded from the computer through the implemented data recording system at 25.6Mbps. Moreover, a dynamic oscilloscope function is developed in MATLAB using this online data recording scheme. / Modulära multilevel-omvandlare (MMC) är den föredragna omvandlarlösningen i flexibla växelströmstransmissionssystem (FACTS) och applikationer med högspänningslikström (HVDC). Detta beror på den höga kvaliteten på spännings- och strömsignalerna, lägre totala förluster och färre problem med omkopplingsrelaterad EMI. Utan ett effektivt och snabbt dataregistreringssystem kan dock samplade data från ström- och spänningsmätkort orsaka långa latenser i styrsystemet och göra det svårt att analysera driften av MMC:er. I denna avhandling utvecklas en FPGA-baserad styrning med sluten slinga och ett höghastighetsdataregistreringssystem för en lågeffekts enfas MMCprototyp. I prototypen finns ett dataöverföringssystem baserat på standarden RS485 (TIA/EIA-485). Detta protokoll erbjuder en robust lösning för att överföra data över bullriga miljöer. Ett schema för direkt minnesåtkomst (DMA) används för att överföra samplade data från den programmerbara logiken (PL) till bearbetningsundersystemet (PS) i Zynq-7000 SOC. Dessutom implementerades en asymmetrisk multiprocessing (AMP)-mekanism på de två processorkärnorna i PS. Den första processorn styr kraftöverföringen till och från elnätet, och den andra processorn kör ethernetapplikationen för att överföra samplade data till datorn med MATLAB. För styrning med sluten slinga av denna MMC-prototyp implementeras en faslåst slinga (PLL), en proportionell resonansströmkontroller (PR) och en energikontrollslinga för balansering och kontroll av kondensatorspänning. Resultaten visade att uteffekten från denna enfasiga MMC-prototyp är under kontroll och varje undermoduls kondensatorspänning är balanserad och laddad till önskat värde. Samplade data kan spelas in från datorn genom det implementerade dataregistreringssystemet vid 25,6 Mbps. Dessutom utvecklas en dynamisk oscilloskopfunktion i MATLAB med hjälp av detta onlinedataregistreringsschema.

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