297,831 research outputs found

    The Behaviour of Finely Ground Bottom Ash in Portland Cement

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    The aim of this project was to assess the effects of finely ground MSWI bottom ash in Portland cement. Mortar mixes were prepared with 10% and 40% replacement of cement by ground IBA and then tested with regards to their material composition and engineering behaviour. IBA was found not to be inert, but showed some degree of reactivity. Replacement of cement with IBA was found to have no detrimental effects at low concentrations. This was not the case for 40% replacement, where cement replacement greatly affected strength, creep and drying shrinkage

    Darwinian Data Structure Selection

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    Data structure selection and tuning is laborious but can vastly improve an application's performance and memory footprint. Some data structures share a common interface and enjoy multiple implementations. We call them Darwinian Data Structures (DDS), since we can subject their implementations to survival of the fittest. We introduce ARTEMIS a multi-objective, cloud-based search-based optimisation framework that automatically finds optimal, tuned DDS modulo a test suite, then changes an application to use that DDS. ARTEMIS achieves substantial performance improvements for \emph{every} project in 55 Java projects from DaCapo benchmark, 88 popular projects and 3030 uniformly sampled projects from GitHub. For execution time, CPU usage, and memory consumption, ARTEMIS finds at least one solution that improves \emph{all} measures for 86%86\% (37/4337/43) of the projects. The median improvement across the best solutions is 4.8%4.8\%, 10.1%10.1\%, 5.1%5.1\% for runtime, memory and CPU usage. These aggregate results understate ARTEMIS's potential impact. Some of the benchmarks it improves are libraries or utility functions. Two examples are gson, a ubiquitous Java serialization framework, and xalan, Apache's XML transformation tool. ARTEMIS improves gson by 16.516.5\%, 1%1\% and 2.2%2.2\% for memory, runtime, and CPU; ARTEMIS improves xalan's memory consumption by 23.523.5\%. \emph{Every} client of these projects will benefit from these performance improvements.Comment: 11 page

    Space Alignment Based on Regularized Inversion Precoding in Cognitive Transmission

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    For a two-tier Multiple-Input Multiple-Output (MIMO) cognitive network with common receiver, the precoding matrix has a compact relationship with the capacity performance in the unlicensed secondary system. To increase the capacity of secondary system, an improved precoder based on the idea of regularized inversion for secondary transmitter is proposed. An iterative space alignment algorithm is also presented to ensure the Quality of Service (QoS) for primary system. The simulations reveal that, on the premise of achieving QoS for primary system, our proposed algorithm can get larger capacity in secondary system at low Signal-to-Noise Ratio (SNR), which proves the effectiveness of the algorithm

    Studies of human dynamic space orientation using techniques of control theory

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    Three-dimensional contact analog display system development for use in surface, subsurface, air, and space vehicle

    Studies of human dynamic space orientation using techniques of control theory Status report, Jun. 1967 - Jun. 1968

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    Human dynamic space orientation using techniques of control theor

    Studies of human dynamic space orientation using techniques of control theory Status report

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    Human dynamic space orientation using control theory technique

    The Effect of Co-Combusted Biomass-Coal Fly Ash on the Behaviour Portland Cement

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    This project has investigated the hydration behaviour of pfa-OPC blended cements, comparing conventional pfa with that obtained from co-firing of coal with biomass (palm kernel expeller). Calorimetry, thermal analysis and electron microscopy have been used to investigate the compositions and microstructures of the hydrated pastes. These have been used to explain the materials’ engineering properties (strength development and workability). The results showed that, in the short term, the behaviour of the co-fired material is comparable with that of conventional pfa, there being no discernable differences between the two systems

    Dynamic microscopic structures and dielectric response in the cubic-to-tetragonal phase transition for BaTiO3 studied by first-principles molecular dynamics simulation

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    The dynamic structures of the cubic and tetragonal phase in BaTiO3 and its dielectric response above the cubic-to-tetragonal phase transition temperature (Tp) are studied by first-principles molecular dynamics (MD) simulation. It's shown that the phase transition is due to the condensation of one of the transverse correlations. Calculation of the phonon properties for both the cubic and tetragonal phase shows a saturation of the soft mode frequency near 60 cm-1 near Tp and advocates its order-disorder nature. Our first-principles calculation leads directly to a two modes feature of the dielectric function above Tp [Phys. Rev. B 28, 6097 (1983)], which well explains the long time controversies between experiments and theories
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