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The purpose of this investigation is to research the utility of a standardized generic microprocessor assembly language. More precisely, use of a generic language implementation on a given microprocessor and its effect on programmer productivity will be investigated. Programmer productivity will be scored in terms of an inverse function of the time taken to complete a programming task correctly. Shorter times imply better programmer productivity and longer times imply the opposite

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<p>  </p> <p>In the practical applications of colloidal dispersions and suspensions, such as inks, paints, and food industry, the suspended particles must be stabilized, and remain well-dispersed for long times. Particles which are more dense than the suspending media may sediment rapidly, even with no agglomeration occurring, under many conditions of size and density difference. Then, a dispersant would be necessary for stabilization of particle suspensions against both agglomeration and sedimentation, while the suspensions should remain flowable in many applications. Moreover, when many aqueous suspension media may contain salts, the dispersant also needs to be an effective stabilizer against sedimentation under the specific salinity conditions of that application.</p> <p>DDAB (didodecyldimethylammonium bromide) , a cationic double-chain surfactant, forms lamellar liquid crystal phases when dispersed in water. It also easily forms aqueous vesicle dispersions (unilamellar closed particles with an internal solvent compartment) and liposomes (multilamellar vesicles, MLVs, or lamellar liquid crystallites) at relatively low DDAB weight fractions, <em>w</em>_D. To better understand the phase/dispersion behavior of DDAB and the corresponding optical properties, new analytical solutions of the spherical particles have been obtained for the light scattering theory in the Rayleigh (R) and the Rayleigh-Debye-Gans (RDG) regimes, for single and independent scattering. Moreover, the specific Rayleigh ratio <em>R</em>_q** and the specific turbidity <em>t</em>** were derived analytically for both scattering regimes. Spectroturbidimetry (ST) data at 25 °C for DDAB were compared to the <em>t</em>** predictions. <em>t</em>** data for DDAB vesicles are consistent with the RDG predictions, which are also used to estimate the vesicle sizes.</p> <p>For a better understanding of the effect of the preparation method and salinity on the formation of DDAB vesicles, spectroturbidimetry was used to measure the average radius of the unilamellar DDAB vesicles, which were prepared via two different methods in water and in NaBr salt solutions. The radius was ~24 nm after sonication (SS method) and ~74 nm after extrusion/ultrafiltration (SE method). The radii were larger when the vesicles were produced in 10 mM NaBr, ~65 nm for the SS method and ~280 nm for the SE method. The <em>t</em>** values of these vesicular dispersions increased with decreasing <em>w</em>_D values, until a constant value was reached at <em>w</em>_D*, which depends on the preparation method and the dispersion medium. The constant values of <em>t</em>** are indicative of single and independent scattering, and were used to estimate vesicle radii by solving the <em>t</em>** equations derived for the RDG regime. Estimates of the average distances between the vesicles and their corresponding Debye lengths were obtained to evaluate the importance of inter-vesicle electrostatic interactions, which could lead to dependent scattering at higher weight fractions.</p> <p>DDAB prepared with magnetic stirring of multilamellar liposomes, followed by ultrasonication to generate unilamellar vesicles, were found to have very high viscosities at very low shear stresses at DDAB weight fractions <em>w</em>D from 0.025 to 0.027. The vesicles had average diameters ranging from 68 to 80 nm, as previously determined from spectroturbidimetry. These vesicle dispersions stabilized suspensions of monodisperse spherical amorphous silica particles with diameters of <em>d</em>_sed = 454 nm, 691 nm, and 826 nm against sedimentation, at least for several weeks. Similar results were obtained for suspensions, in DDAB vesicle dispersions, of polydisperse, nonspherical, crystalline titania particles with sizes ranging from ca. 96 nm to 156 nm. At the relatively low values of <em>w</em>_D = 0.009 and 0.018, the effective viscosities,<em> h</em>eff, of the DDAB dispersions, determined from the sedimentation velocities, ranged from 1.35 to 1.87 cP and from 4.34 to 5.57 cP, respectively. At <em>w</em>_D = 0.027 for the silica particles with <em>d</em>_sed = 454 nm, or at <em>w</em>_D = 0.025 for all other particles considered, <em>h</em>_eff was essentially infinite, and each vesicle dispersion behaved as a gel at low shear stresses. At higher shear stresses, however, the dispersions were highly shear-thinning, and flowable in a capillary tube under gravity. This behavior is critical for the practical applications of such dispersions for paints and inkjet printing. To further understand the feasibility of the vesicle stabilization mechanism at various NaBr concentrations, <em>w</em>NaBr, the salinity effects on the stabilization of silica particles against sedimentation were also examined. It was found that at <em>w</em>_NaBr < 0.0020 and at <em>w</em>D > 0.060, the DDAB dispersion could stabilize silica particles against sedimentation for at least two weeks. The relationship of the phase and dispersion behavior of DDAB/aqueous NaBr solutions to their stabilizing effectiveness will be further studied.</p> <p>A first discovery of iridescent liquid-like aqueous vesicle dispersions formed from the DDAB is also reported. Although iridescence arises from some solid crystallites, thin films, and colloidal crystals, it had never been observed in systems that are liquid-like. Visual observations and ST at wavelengths of 350 nm to 700 nm were used to determine vesicle sizes and microstructure formation in dispersions for DDAB weight fractions <em>w</em>D between 0.020 to 0.030. The DDAB vesicle dispersions exhibited iridescent colors for <em>w</em>D = 0.023 to 0.027, due to the formation of “soft” crystallites formed by self-assembled vesicles. Effective vesicle radii from 30 to 60 nm were inferred from the ST measurements. The volume fractions of the vesicles <em>f</em>v and their effective volume fractions <em>f</em>v*, which account for the electrostatic double layers around a vesicle, were also estimated. The high values of <em>f</em>v* for the iridescent dispersions indicate that they contain neighboring vesicles with highly overlapping electrostatic double layers, even though their values of <em>f</em>v remain relatively low. Hence, strong electrostatic repulsive interactions arise between the vesicles. These interactions probably drive the formation of the “soft” crystallites, and thus the observed iridescence. Nevertheless, these “soft” crystallites, which could be easily broken up but were quick to reform, remain suspended. Consequently, these vesicle dispersions still flowed as a bulk dispersion with a high viscosity; the dispersion as a whole remained liquid-like or as a “liquid gem”, in contrast to what occurs to the other colloidal crystals made of rigid colloids. Beside their beautiful appearances, these DDAB vesicle dispersions also act as effective stabilizers of dense silica suspensions against sedimentation even at relatively low values of <em>w</em>D. </p>

<p> Many industries have legacy software systems which are definitely important to them but are however, difficult to maintain due to a lack of understanding of those systems. This occurs as a result of inadequate or inconsistent documentation. Although the costs of redesigning the system may be large, some organizations still plan to reverse engineer the software specification documents from the code to alleviate a large burden from such endeavour. This thesis provides an incremental and modular approach to create a process and tools to extract the semantics of legacy assembly code.</p> <p> Our techniques consist of static analysis and symbolic interpretation in order to reverse engineer the semantics of legacy software. We examine the case of IBM-1800 programs in detail. From the abstract model of the operational semantics of IBM-1800, we simultaneously obtain an emulator and a symbolic analysis process. Augmented with control flow information, we can use the symbolic analysis to provide complete semantics for the code sequences of interest. We can also generate Data Flow Graphs to depict the flow of data in those code segments. The whole process of extracting semantic information from the assembler codes is fully automated with only a little human intervention at the initial step.</p> <p> We use Haskell as our implementation language and its important features help us to create modular and well structured software. The literate programming documentation style in this thesis increases the readability and consistency of the implementation's documentation.</p> <p> The process and the associated tools created in this thesis are used in a large reverse engineering project, which has a goal to extract requirements specification from legacy assembly code. This project is funded jointly by Ontario Power Generation (OPG) and CITO (Communications and Information Technology Ontario).</p> / Thesis / Master of Applied Science (MASc)

We study the formation of novel bicontinuous phases in binary mixtures of AB diblock copolymers (DBCP) using the polymeric self-consistent field theory. We predict that the bicontinuous double-diamond (DD) and plumber’s nightmare (P) phases, which are metastable phases of neat diblock copolymers, could be stablized in gyroid-forming A-minority DBCPs via the blending of specifically designed A-majority DBCPs. The mechanisms of stabilizing different bicontinuous phases are revealed by analyzing the spatial distribution of the different DBCPs. It is found that the A-majority DBCPs residing mainly in the nodes of the structure, thus alleviating the packing frustration of the A-blocks. Furthermore, a local segregation of the two DBCPs occurs at the AB interface, thus regulating the local curvature of the interfaces. A synergetic interplay of these two mechanisms results in a larger stable region of the DD and P phases via the addition of tailored A-majority DBCPs. The theoretical study provides an efficient route to obtain novel bicontinuous phases. / Thesis / Master of Science (MSc)