Global ETD Search

1	Compiler Testing of C11 Atomics for Arm and RISC-V Adolfsson, Hampus January 2022 (has links) The C11 standard introduced atomic types and operations, with an accompanying memory model, to enable the use of shared variables in concurrent programs. In this thesis, I demonstrate how compilers can be tested, in a way that is deterministic and covers the entire set of atomic operations, to ensure they correctly implement C11 atomics and the C11 memory model. I use a large set of short concurrent programs (”litmus tests”), generated from a model written in a specification language and based on a formalized C11 memory model. Each test program is compiled and run with a model checker, to determine the possible outcomes; any program with an outcome that is possible after compilation but not allowed by C11 is a failed test case. As an alternative to model checking, I also test a nondeterministic, hardware-based method for running tests, but I find that this method is too inaccurate to be useful. I test IAR and gcc compilers for Arm and RISC-V; all of these compilers pass all tests. Out of three compilers with purposefully inserted bugs, all are correctly identified as faulty. This testing process thus shows some promise, but further evaluation is needed. compiler compiler testing atomics c11 atomics arm risc-v Computer Systems Datorsystem
2	A MapReduce Framework for Heterogeneous Computing Architectures Elteir, Marwa Khamis 01 June 2013 (has links) Nowadays, an increasing number of computational systems are equipped with heterogeneous compute resources, i.e., following different architecture. This applies to the level of a single chip, a single node and even supercomputers and large-scale clusters. With its impressive price-to-performance ratio as well as power efficiently compared to traditional multicore processors, graphics processing units (GPUs) has become an integrated part of these systems. GPUs deliver high peak performance; however efficiently exploiting their computational power requires the exploration of a multi-dimensional space of optimization methodologies, which is challenging even for the well-trained expert. The complexity of this multi-dimensional space arises not only from the traditionally well known but arduous task of architecture-aware GPU optimization at design and compile time, but it also arises in the partitioning and scheduling of the computation across these heterogeneous resources. Even with programming models like the Compute Unified Device Architecture (CUDA) and Open Computing Language (OpenCL), the developer still needs to manage the data transfer be- tween host and device and vice versa, orchestrate the execution of several kernels, and more arduously, optimize the kernel code. In this dissertation, we aim to deliver a transparent parallel programming environment for heterogeneous resources by leveraging the power of the MapReduce programming model and OpenCL programming language. We propose a portable architecture-aware framework that efficiently runs an application across heterogeneous resources, specifically AMD GPUs and NVIDIA GPUs, while hiding complex architectural details from the developer. To further enhance performance portability, we explore approaches for asynchronously and efficiently distributing the computations across heterogeneous resources. When applied to benchmarks and representative applications, our proposed framework significantly enhances performance, including up to 58% improvement over traditional approaches to task assignment and up to a 45-fold improvement over state-of-the-art MapReduce implementations. / Ph. D. Atomics Graphics Processing Units Programming Models Heterogeneous Computing MapReduce
3	Engenharia de interações seletivas para a geração de estados estacionários do campo de radiação / Engineering selective interactions for generating of nonclassical steady-state of the radiation field Rosado Mercado, Wilson Enrique 20 February 2015 (has links) Neste trabalho, descrevemos vários protocolos para a geração de estados estacionários não clássicos, suportados principalmente pela engenharia de hamiltonianos seletivos Jaynes-Cummings, e de reservatórios atômicos. Começamos apresentando um protocolo para engenhar interações seletivas lineares e não lineares do tipo Jaynes-Cummings como também simulações numéricas para comprovar a eficácia de nosso esquema. Analisamos também como aplicar essas interações seletivas à preparação e proteção de estados de Fock estacionários via reservatório atômico. Esta estratégia combina a ação dos mecanismo de amortecimento da cavidade com os de um reservatório atômico engenhado para conduzir uma distribuição térmica inicial a um estado de Fock estacionário. A mesma técnica pode ser utilizada para fatiar as distribuições de probabilidade no espaço de Fock, permitindo assim a preparação de uma variedade de estados de equilíbrio não clássicos. Também apresentamos um protocolo para a engenharia de interações upper-bound e sliced Jaynes-Cummings e anti-Jaynes-Cummings na eletrodinâmica quântica de cavidade. No Hamiltoniano upper-bound, a interação átomo-campo está confinada a um subespaço de Fock com estados que vão desde Ι0> até Ι4> enquanto que no Hamiltoniano sliced vão desde ΙM> até ΙM + 4>. Mostramos como construir Liouvillianos upper-bound independentemente da engenharia do Hamiltoniano upper-bound. Os Hamiltonianos e Liouvillianos upper-bound e sliced podem ser usados, entre outras aplicações, para gerar estados de Fock estacionários no modo da cavidade e para a implementação de um dispositivo de tesoura quântica para truncagem de estado óptico. Finalmente, propomos um esquema para a preparação de estados emaranhados estacionários em redes bosônicas dissipativas. Descrevemos a sua aplicação em um sistema de cavidades acopladas interagindo com um reservatório construído por átomos de três níveis. Os emblemáticos estados Bell e NOON, e estados multipartites (tipo W) podem ser produzidos com alta fidelidade e pureza. / In this work, we describe various protocols for the generation of nonclassical steady-state, supported mainly by the engineering selective Hamiltonian Jaynes-Cummings-type, and atomics reservoirs. We started presenting a framework to engineer nonlinear selective JaynesCummings-type interactions with numerical simulations to prove the effectiveness of our scheme. We further analyses how to apply these selective interactions to the preparation and protection of steady Fock states via atomic reservoir. This strategy combines the action of cavity damping mechanisms with that of an engineered atomic reservoir to drive an initial thermal distribution to a Fock equilibrium state. The same technique can be used to slice probability distributions in the Fock space, thus allowing the preparation of a variety of non-classical equilibrium states. Also we present a protocol to engineer upper-bound and sliced Jaynes-Cummings-type and anti-Jaynes-Cummings-type Hamiltonians in cavity quantum electrodynamics. In the upper-bounded Hamiltonians, the atom-field interaction is confined to a subspace of Fock states ranging from Ι0> up to Ι4>, while in the sliced interaction the Fock subspace ranges from ΙM> up to ΙM + 4>. We also show how to build upper-bounded and sliced Liouvillians irrespective of engineering Hamiltonians. The upper-bounded and sliced Hamiltonians and Liouvillians can be used, among other applications, to generate steady Fock states of a cavity mode and for the implementation of a quantum-scissors device for optical state truncation. Finally we propose a scheme for the preparation of steady entanglements in bosonic dissipative networks. We describe its implementation in a system of coupled cavities interacting with an engineered reservoir built up of three-level atoms. Emblematic bipartite (Bell and NOON) and multipartite (W -class) states can be produced with high fidelity and purity. Atomics reservoirs Entanglements states Estados emaranhados Estados estacionários não clássicos Interação seletiva Nonclassical steady-state Reservatório atômico Selective interactions
4	Engenharia de interações seletivas para a geração de estados estacionários do campo de radiação / Engineering selective interactions for generating of nonclassical steady-state of the radiation field Wilson Enrique Rosado Mercado 20 February 2015 (has links) Neste trabalho, descrevemos vários protocolos para a geração de estados estacionários não clássicos, suportados principalmente pela engenharia de hamiltonianos seletivos Jaynes-Cummings, e de reservatórios atômicos. Começamos apresentando um protocolo para engenhar interações seletivas lineares e não lineares do tipo Jaynes-Cummings como também simulações numéricas para comprovar a eficácia de nosso esquema. Analisamos também como aplicar essas interações seletivas à preparação e proteção de estados de Fock estacionários via reservatório atômico. Esta estratégia combina a ação dos mecanismo de amortecimento da cavidade com os de um reservatório atômico engenhado para conduzir uma distribuição térmica inicial a um estado de Fock estacionário. A mesma técnica pode ser utilizada para fatiar as distribuições de probabilidade no espaço de Fock, permitindo assim a preparação de uma variedade de estados de equilíbrio não clássicos. Também apresentamos um protocolo para a engenharia de interações upper-bound e sliced Jaynes-Cummings e anti-Jaynes-Cummings na eletrodinâmica quântica de cavidade. No Hamiltoniano upper-bound, a interação átomo-campo está confinada a um subespaço de Fock com estados que vão desde Ι0> até Ι4> enquanto que no Hamiltoniano sliced vão desde ΙM> até ΙM + 4>. Mostramos como construir Liouvillianos upper-bound independentemente da engenharia do Hamiltoniano upper-bound. Os Hamiltonianos e Liouvillianos upper-bound e sliced podem ser usados, entre outras aplicações, para gerar estados de Fock estacionários no modo da cavidade e para a implementação de um dispositivo de tesoura quântica para truncagem de estado óptico. Finalmente, propomos um esquema para a preparação de estados emaranhados estacionários em redes bosônicas dissipativas. Descrevemos a sua aplicação em um sistema de cavidades acopladas interagindo com um reservatório construído por átomos de três níveis. Os emblemáticos estados Bell e NOON, e estados multipartites (tipo W) podem ser produzidos com alta fidelidade e pureza. / In this work, we describe various protocols for the generation of nonclassical steady-state, supported mainly by the engineering selective Hamiltonian Jaynes-Cummings-type, and atomics reservoirs. We started presenting a framework to engineer nonlinear selective JaynesCummings-type interactions with numerical simulations to prove the effectiveness of our scheme. We further analyses how to apply these selective interactions to the preparation and protection of steady Fock states via atomic reservoir. This strategy combines the action of cavity damping mechanisms with that of an engineered atomic reservoir to drive an initial thermal distribution to a Fock equilibrium state. The same technique can be used to slice probability distributions in the Fock space, thus allowing the preparation of a variety of non-classical equilibrium states. Also we present a protocol to engineer upper-bound and sliced Jaynes-Cummings-type and anti-Jaynes-Cummings-type Hamiltonians in cavity quantum electrodynamics. In the upper-bounded Hamiltonians, the atom-field interaction is confined to a subspace of Fock states ranging from Ι0> up to Ι4>, while in the sliced interaction the Fock subspace ranges from ΙM> up to ΙM + 4>. We also show how to build upper-bounded and sliced Liouvillians irrespective of engineering Hamiltonians. The upper-bounded and sliced Hamiltonians and Liouvillians can be used, among other applications, to generate steady Fock states of a cavity mode and for the implementation of a quantum-scissors device for optical state truncation. Finally we propose a scheme for the preparation of steady entanglements in bosonic dissipative networks. We describe its implementation in a system of coupled cavities interacting with an engineered reservoir built up of three-level atoms. Emblematic bipartite (Bell and NOON) and multipartite (W -class) states can be produced with high fidelity and purity. Estados emaranhados Estados estacionários não clássicos Interação seletiva Reservatório atômico Atomics reservoirs Entanglements states Nonclassical steady-state Selective interactions
5	Validating results from the Molten Salt Reactor Experiment by use of turbulent CFD simulations : A study of a modified U-tube shell-and-tube primary heat exchanger and radiator with molten salts Akner, Malcolm January 2021 (has links) Background Nuclear reactors utilizing molten fuels rather than solid fuels show a massive advantage in energy yield, waste handling and safety features. The only successful reactor utilizing a molten fuel was called the ‘Molten Salt Reactor Experiment’ (MSRE), built and operated in the Oak Ridge national laboratory (ORNL) in Tennessee, U.S.A. during the 1960s. The molten salts in question are fluoride compounds under the name of “FLiBe”. In this thesis, the heat exchangers of the MSRE are modelled and simulated, with the aim to test whether current computational fluid dynamics (CFD) software and mathematical models can accurately predict molten salt heat transfer behaviour. Methods All programs used are open-source and/or free-access to facilitate open collaboration between researchers in this growing field. All models and findings produced in this thesis are free to use for future research. The program Onshape was used to draw CAD-models based on hand-drawn technical documents released by ORNL. Several programs, e.g., Simscale and Salome, were used to create high detailed meshes of the heat exchangers. The CFD software Simscale and OpenFOAM have been used to simulate the heat exchangers, using the 𝑘 − 𝜔 𝑆𝑆𝑇 Reynolds averaged Navier-Stokes (RANS) turbulence model to perform a multiregion conjugate heat transfer (CHT) analysis. The program Paraview has been used for all post-processing on the large datasets. Results A working toolchain with open-source programs for CFD has been identified. Highly detailed, full-scale and accurate CAD-drawings of the two heat exchangers have been produced. Models have been finely meshed, containing tens of millions of cells, with good quality measures. The simulations produced physically sound and valuable data: Great heat transfer predictive capability with high accuracy to the data presented by ORNL. Pressure data showed a consistent over-prediction with a factor of ~2. Possibility of error within the MSRE measurement. Conclusions CHT using modern turbulence methods work well for the intended purpose and can be used by industry to simulate molten salt heat transfer. Open-source programs perform well and can be used by researchers to share ideas and progress. Doubts around certain measurements from the MSRE, showing large uncertainties. Future projects have been outlined to continue the work performed in this thesis. Molten salt reactors show fantastic promise as an energy generation method and should be seriously considered for the future of clean, reliable energy. CFD MSRE CAD CHT experiment molten liquid salt fluid mechanics mechanics fluid LTU nuclear reactor nuclear reactor generation four generation IV copenhagen atomics copenhagen atomics space engineering space engineering aerospace thesis master's thesis master's Malcolm Akner Erik CFD MSRE CAD CHT flytande salt strömningslära strömningsmekanik fluid fluidmekanik LTU kärnreaktor generation fyra generation IV copenhagen atomics rymdteknik flygteknik ingenjör civilingenjör examensarbete Malcolm Akner Erik Aerospace Engineering Rymd- och flygteknik
6	Dinâmica de colisões entre átomos de Rydberg frios / Dymanics of collisions among rydberg atoms Nascimento, Valter Aragão do 25 September 2006 (has links) Processos colisionais envolvendo transferência de energia têm sido intensivamente investigados em amostras de átomos de Rydberg frios nos últimos anos. Alguns grupos de pesquisa têm interpretado tais processos utilizando um modelo de muitos corpos; nosso grupo tem explicado tais processos, considerando a interação de dois corpos em um potencial de ultralongo alcance e o movimento sob a ação de um potencial. Nesta tese nós investigamos tais processos de colisão envolvendo átomos de Rydberg frios, produzidos em uma armadilha magneto-óptica. A investigação da evolução temporal de estados de Rydberg produzidos por colisões para diferentes densidades atômicas nos permite demonstrar que o processo binário é dominante. Além disso, mostramos que a radiação de corpo negro não pode ser desprezada nestes experimentos. Finalmente, sugerimos melhorias para um modelo semi-clássico de dinâmica colisional proposto por nosso grupo. / Collisional processes involving energy transfer have been intensively investigated in samples of cold Rydberg atoms in the last years. Some research groups have interpreted such processes using a many body model; on the other hand our group has explained such processes considering a two body interaction in an ultralong range potential and the atomic motion under the influence of such potential. In this work, we have investigated such atomic collisions involving cold Rydberg atoms, produced in a magneto-optical trap. The time evolution study of the Rydberg states produced by collisions for different atomic densities has shown us that the binary process is dominant in such system. Beyond that, we have shown that the radiation of black body cannot be neglected in these experiments. Finally, we suggest improvements for the semi-classical collissional dynamic model proposed by our group. Armadilha magneto óptica Colisão de dois corpos Collisions of two bodies Trap magneto optical
7	Dinâmica de colisões entre átomos de Rydberg frios / Dymanics of collisions among rydberg atoms Valter Aragão do Nascimento 25 September 2006 (has links) Processos colisionais envolvendo transferência de energia têm sido intensivamente investigados em amostras de átomos de Rydberg frios nos últimos anos. Alguns grupos de pesquisa têm interpretado tais processos utilizando um modelo de muitos corpos; nosso grupo tem explicado tais processos, considerando a interação de dois corpos em um potencial de ultralongo alcance e o movimento sob a ação de um potencial. Nesta tese nós investigamos tais processos de colisão envolvendo átomos de Rydberg frios, produzidos em uma armadilha magneto-óptica. A investigação da evolução temporal de estados de Rydberg produzidos por colisões para diferentes densidades atômicas nos permite demonstrar que o processo binário é dominante. Além disso, mostramos que a radiação de corpo negro não pode ser desprezada nestes experimentos. Finalmente, sugerimos melhorias para um modelo semi-clássico de dinâmica colisional proposto por nosso grupo. / Collisional processes involving energy transfer have been intensively investigated in samples of cold Rydberg atoms in the last years. Some research groups have interpreted such processes using a many body model; on the other hand our group has explained such processes considering a two body interaction in an ultralong range potential and the atomic motion under the influence of such potential. In this work, we have investigated such atomic collisions involving cold Rydberg atoms, produced in a magneto-optical trap. The time evolution study of the Rydberg states produced by collisions for different atomic densities has shown us that the binary process is dominant in such system. Beyond that, we have shown that the radiation of black body cannot be neglected in these experiments. Finally, we suggest improvements for the semi-classical collissional dynamic model proposed by our group. Armadilha magneto óptica Colisão de dois corpos Collisions of two bodies Trap magneto optical
8	台北地區中學生購買行為之研究穆繼誠, Mu, Ji-Cheng Unknown Date (has links) 本篇論文目的在於研究台北地區中學生有關購買行為的知識，消費性動機，炫耀性動機，情報搜集及評估，……的社會化過程，並探討中學生認知發展程度之不同，在消費行為上有何差異。以台北地區隨機抽樣七個學校，六百名學生，問卷調查，統計結果。全文以社會化學說及皮亞杰認知發展學說為理論架構。共分為六章：一、導論。二、研究假設。三、定義變數。四、文獻探討。五、研究發現。六、結論。台北地區中學生購買行為消費性動機炫耀性動機社會化原子學核子學科學 ATOMICS NUCLEAR-SCIENCE SCIENCE

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