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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.

Slow mergers of massive stars

Ivanova, Natalʹi͡a January 2002 (has links)
No description available.

Proof of the finiteness of the modular covariants of a system of binary forms and cogredient points

Wiley, Forbes Bagley, January 1900 (has links)
Thesis (Ph. D.)--University of Chicago, 1914. / Vita. Reprinted from Transactions of the American Mathematical Society, vol. 15 (1914).

Proof of the finiteness of the modular covariants of a system of binary forms and cogredient points

Wiley, Forbes Bagley, January 1900 (has links)
Thesis (Ph. D.)--University of Chicago, 1914. / Vita. Reprinted from Transactions of the American Mathematical Society, vol. 15 (1914).

Fundamental systems of formal modular seminvariants of the binary cubic /

Williams, W. L. G. January 1900 (has links)
Thesis (Ph. D.)--University of Chicago, 1920. / "Private edition distributed by the University of Chicago Libraries." "Reprinted from Transactions of the American mathematical society, volume 22, number 1 (January, 1921)."

Guided automatic binary parallelisation

Zhou, Ruoyu January 2018 (has links)
For decades, the software industry has amassed a vast repository of pre-compiled libraries and executables which are still valuable and actively in use. However, for a significant fraction of these binaries, most of the source code is absent or is written in old languages, making it practically impossible to recompile them for new generations of hardware. As the number of cores in chip multi-processors (CMPs) continue to scale, the performance of this legacy software becomes increasingly sub-optimal. Rewriting new optimised and parallel software would be a time-consuming and expensive task. Without source code, existing automatic performance enhancing and parallelisation techniques are not applicable for legacy software or parts of new applications linked with legacy libraries. In this dissertation, three tools are presented to address the challenge of optimising legacy binaries. The first, GBR (Guided Binary Recompilation), is a tool that recompiles stripped application binaries without the need for the source code or relocation information. GBR performs static binary analysis to determine how recompilation should be undertaken, and produces a domain-specific hint program. This hint program is loaded and interpreted by the GBR dynamic runtime, which is built on top of the open-source dynamic binary translator, DynamoRIO. In this manner, complicated recompilation of the target binary is carried out to achieve optimised execution on a real system. The problem of limited dataflow and type information is addressed through cooperation between the hint program and JIT optimisation. The utility of GBR is demonstrated by software prefetch and vectorisation optimisations to achieve performance improvements compared to their original native execution. The second tool is called BEEP (Binary Emulator for Estimating Parallelism), an extension to GBR for binary instrumentation. BEEP is used to identify potential thread-level parallelism through static binary analysis and binary instrumentation. BEEP performs preliminary static analysis on binaries and encodes all statically-undecided questions into a hint program. The hint program is interpreted by GBR so that on-demand binary instrumentation codes are inserted to answer the questions from runtime information. BEEP incorporates a few parallel cost models to evaluate identified parallelism under different parallelisation paradigms. The third tool is named GABP (Guided Automatic Binary Parallelisation), an extension to GBR for parallelisation. GABP focuses on loops from sequential application binaries and automatically extracts thread-level parallelism from them on-the-fly, under the direction of the hint program, for efficient parallel execution. It employs a range of runtime schemes, such as thread-level speculation and synchronisation, to handle runtime data dependences. GABP achieves a geometric mean of speedup of 1.91x on binaries from SPEC CPU2006 on a real x86-64 eight-core system compared to native sequential execution. Performance is obtained for SPEC CPU2006 executables compiled from a variety of source languages and by different compilers.

Optimising Dynamic Binary Modification across ARM microarchitectures

Gorgovan, Cosmin January 2017 (has links)
Dynamic Binary Modification (DBM) is a technique for modifying applications at runtime, working at the level of native code. It has numerous applications, including instrumentation, translation and optimisation. However, DBM introduces a performance overhead, which in some cases can dominate execution time, making many uses impractical. While avenues for reducing this overhead have been widely explored on x86, ARM, an architecture gaining widespread adoption, has received little attention. Consequently, the overhead of DBM on ARM, as reported in the literature and measured using the available DBM systems, has fallen behind the state-of-the-art by one or two orders of magnitude. The research questions addressed in this thesis are: 1) how to develop low overhead DBM systems for the ARM architecture, and 2) whether new optimisations are plausible and needed. Towards that end, a number of novel optimisations were developed and evaluated specifically to address the sources of overhead for DBM on various ARM microarchitectures. Furthermore, many of the optimisations in the literature were ported to ARM and evaluated. This work was enabled by a new DBM system, named MAMBO, created specifically for this purpose. MAMBO, using the optimisations presented in this thesis, is able to achieve an overhead an order of magnitude smaller than that of the most efficient DBM system for ARM available at the start of this PhD.

Binary mixture flammability characteristics for hazard assessment

Vidal Vazquez, Migvia del C. 01 November 2005 (has links)
Flammability is an important factor of safe practices for handling and storage of liquid mixtures and for the evaluation of the precise level of risk. Flash point is a major property used to determine the fire and explosion hazards of a liquid, and it is defined as the minimum temperature at which the vapor present over the liquid at equilibrium forms a flammable mixture when mixed with air. Experimental tests for the complete composition range of a mixture are time consuming, whereas a mixture flash point can be estimated using a computational method and available information. The information needed for mixture flash point predictions are flashpoints, vapor pressures, and activity coefficients as functions of temperature for each mixture component. Generally, sufficient experimental data are unavailable and other ways of determining the basic information are needed. A procedure to evaluate the flash point of binary mixtures is proposed, which provides techniques that can be used to estimate a parameter that is needed for binary mixture flash point evaluations. Minimum flash point behavior (MFPB) is exhibited when the flash point of the mixture is below the flash points of the individual components of the mixture. The identification of this behavior is critical, because a hazardous situation results from taking the lowest component flash point value as the mixture flash point. Flash point predictions were performed for 14 binary mixtures using various Gex models for the activity coefficients. Quantum chemical calculations and UNIFAC, a theoretical model that does not require experimental binary interaction parameters, are employed in the mixture flash point predictions, which are validated with experimental data. MFPB is successfully predicted using the UNIFAC model when there are insufficient vapor liquid data. The identification of inherent safety principles that can be applied to the flammability of binary liquid mixtures is also studied. The effect on the flash point values of three binary mixtures in which octane is the solute is investigated to apply the inherent safety concept.

A study of rapid thermal selenization process of CuInSe2 films

Pan, Chia-jui 11 July 2009 (has links)
By evaporating single element to grow two kinds of stacked layer precursors In/Cu/Se and In/Se/Cu first, In/Cu/Se precursor forms as CuSe2, CuSe and In metal phase, but In/Se/Cu precursor forms mainly as Cu11In9 alloy, In metal phase and amorphous Se. In RTA selenization process, the two kinds of stacked layer precursors form to CuInSe2 (for short as CIS) thin film in different reaction mechanisms, but both of the two stacked layers form to CIS with rough surface and uncompact structure, not the ideal thin film. Replacing by co-evaporating two elements to grow two kinds of binary stacked layrer precursors InSe/CuSe/Se and InSe/Cu/InSe/Se, finds that, after the RTA selenization process, both of the two precursors form CIS with good smoothness and compactness, and InSe/CuSe/Se precursor with much better structure than the other, having mean grain size in about 1~3£gm. In this result, appears that if skipping the stage which single element reacts with Se, generating the selenide InxSey, CuxSey (Such as InSe, In2Se3, CuSe, Cu2Se et cetera.), and using In-Se, Cu-Se binary stacked precursors in RTA process directly can acquire better CIS structure. And then, growing InSe/CuSe/Se stacked layer on Mo metal back contact, finds the phenomenon that the formed CIS thin film has many circle bulges structure on Mo thin film. After investigating this case, the reason was considered as the remaining compressive stress of Mo thin film (-272.9MPa). The interface problem of Mo/CIS has been solved by tuning the remaining stress of Mo with 1£gm thickness to compressive stress -194MPa, and 1£gm thickness CIS thin film is grown on that. However, if the remaining stress continuingly drecrese to almost no stress 1MPa or tensile stress 709.9MPa, CIS thin film peels with Mo thin film from the substrate. In the end, analyzing the CIS thin film formed by InSe/CuSe/Se stacked layer precursor (Cu/In ratio is 24%/26%), the result shows that the CIS film is a P-type In-rich thin film, the sheet resistence is 6.8*106£[/ ¡¼, carrier mobility is 1.103*102 cm2/V-s, carrier density is 1.318*1018 cm-3, and energy gap is about 1.0eV, the absorption coefficient is above 6.5*104cm-1, and the composition all over the film is very close to each other¡Aappearing this film with nice composition homogenization.

Molecular Investigation of the Clostridium difficile Binary Toxin

Metcalf, Devon 17 December 2012 (has links)
This thesis is an investigation of the binary toxin of Clostridium difficile. The aim was to improve the understanding of the role of the binary toxin in pathogenesis. Quantitative real-time PCR (qPCR) was used to study expression of cdtA encoding the binary toxin enzymatic domain, cdtR encoding the binary toxin regulator and tcdB encoding toxin B, in response to growth phase and antimicrobial treatments in 2 C. difficile strains. Validation of a set of stable reference genes was required prior to qPCR analysis of gene expression. A universal set of genes could not be identified and reference genes should be validated on a strain-specific basis. Significant increases or decreases in expression were observed in response to levofloxacin and enrofloxacin exposure. The 2 strains selected were from different ribotypes and did not always share expression patterns. Binary toxin loci were sequenced in and compared between 10 C. difficile strains. A non-sense mutation in the cdtR gene of a ribotype 078 strain was identified and found to be restricted to toxinotype V isolates. This mutation is predicted to result in a truncated, non-functional protein. Despite the mutation, cdtA expression was still detected by qPCR. Finally, an evaluation of commercial nucleic acid extraction kits was performed. All kits produced RNA of adequate quality and yield, however, RNA isolated using the the Roche MagNA Pure LC RNA Isolation Kit could not be analyzed using the Agilent Bioanalyzer. It could not properly assign RNA integrity numbers due to a failure to remove small RNAs which were interpreted as degradation. All kits were suitable for DNA extraction with the exception of the MagNA Pure LC DNA Isolation Kit III which produced sheared DNA. In conclusion, this study demonstrated that the binary toxin regulator isn’t necessary for toxin expression and suggests other regulators of expression exist. Binary toxin gene expression did not necessarily correlate with expression of tcdB and expression levels vary between strains. This study also highlighted how the heterogeneity of C. difficile complicates gene expression experiments and the need for assessment of nucleic acid extraction methods due to critical variations between established commercial systems.

Tools, Techniques, and Trade-offs when Porting Large Software Systems to New Environments

Kågström, Simon January 2008 (has links)
Computer hardware and software evolve very fast. With the advent of chip-multiprocessors and symmetric multithreading, multiprocessor hardware configurations are becoming prevalent. For software, new hardware and requirements such as security, performance and maintainability drive the development of new runtime environments, virtual machines and programming methodologies. These trends present problems when porting legacy software. Multiprocessor hardware require ports of uniprocessor operating system kernels while new software environments might require that programs have to be ported to different languages. This thesis examines the tradeoff between performance and development effort for software porting with case studies in operating system porting to multiprocessors and tool support for porting C and C++ applications to Java virtual machines. The thesis consists of seven papers. The first paper is a survey of existing multiprocessor development approaches and focuses on the tradeoff between performance and implementation effort. The second and third papers describe the evolution a traditional lock-based multiprocessor port, going from a serialized “giant locked” port and evolving into a coarse-grained implementation. The fourth paper instead presents an alternative porting approach which aims to minimize development effort. The fifth paper describes a tool for efficient instrumentation of programs, which can be used during the development of large software systems such as operating system kernels. The sixth and seventh papers finally describe a binary translator which translates MIPS binaries into Java bytecode to allow low-effort porting of C and C++ applications to Java virtual machines. The first main contributions of this thesis is an in-depth investigation of the techniques used when porting operating system kernels to multiprocessors, focusing on development effort and performance. The traditional approach used in the second and third papers required longer development time than expected, and the alternative approach in the fourth paper can therefore be preferable in some cases. The second main contribution is the development of a binary translator that targets portability of C and C++ applications to J2ME devices. The last two papers show that the approach is functional and has good enough performance to be feasible in real-life situations.

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