7,660 research outputs found

    Advanced Computer Graphics Aided Molecular Visualization and Manipulation Softwares: The Hierarchy of Research Methodologies

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    In the present day, the huge obstacles, and the major technical problems encountered by the teaching and research faculties, academicians, industrial specialists, laboratory demonstrators and instructors, fellow students and researchers, etc. are to adopt integrative approaches of demonstrating (learning) chemistry and chemical education, and the realistic ways of delivering (grasping) scientific materials articulately with graceful and effortless manner. Towards minimizing these challenges, various audio-visual tools and technologies, advanced computer aided molecular graphics, freely available electronic gadgets assisted chemistry and chemical education apps, human unreadable data reading and accessing softwares, etc. are being incorporated worldwide as the most indispensable physical and electronic means for successful professionalisms. This short article is essentially a collective report underscoring extraordinary approaches, incredible efforts, and innovative skills of the computer based chemical and molecular graphics towards illuminating intrinsic parts of the chemistry and chemical education, and revealing various aspects of the cutting -edge research. As their representatives, herein, the different type computer coding languages based graphical tools such as Molden, GaussView, Jmol, and Visual Molecular Dynamics (VMD) are referred, and elucidated their potential applications and remarkable attempts in the advancement of diverse areas of chemistry and chemical education. Beside this, the most essential graphical features, unique rendering abilities with magnificent views, splendid visualizing skills, awesome data accessing functionalities, etc. of each of them, and their invaluable roles for studying complex molecules, biomolecules, crystals, and the entire material assemblies as well as for investigating global and local molecular physicochemical properties are presented concisely with the special stresses on their relatively better and comparatively more applicable distinctive attributes explicitl

    Configuration planning on an ICL computer utilizing a stochastic network analysis package

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    M.Sc (Computer Science.)This dissertation details the implementation of SNAP, a stochastic network analysis package, as the basis of an in-house computer configuration planning facility. The work was performed at Head Office, Gold Fields of South Africa Limited, Johannesburg, South Africa (GFSA) during the period April 1980 to December 1981. SNAP was developed by the Institute of Applied Computer Science at the University of Stellenbosch, Stellenbosch, South Africa. The implementation of SNAP at GFSA signalled the first in-house SNAP facility, and the first SNAP implementation on an ICL computer (although implementation had been in progress at another ICL site since 1979). Although this dissertation is very specific in nature, it is intended to provide an insight into the methodology employed in planning and implementing an in-house configuration planning facility. An overview of multiclass queueing network models and the SNAP package is provided, although no attempt is made to explain the stochastic theory of queueing networks in any detail. Attention is thereafter focussed on the various phases of the project. Problems were encountered in monitoring performance data, and these are looked at in some depth. The question of workload characterization and the difficulties of producing a satisfactory GFSA classification strategy are then presented. The model design, calibration and validation stages are explained using the GFSA model. Thereafter, use of the model for prediction purposes is illustrated by means of a number of examples. Finally, tne memory management model is discussed - main memory does not form part of the SNAP model and has to be dealt with as a separate issue

    DINOMO: An Elastic, Scalable, High-Performance Key-Value Store for Disaggregated Persistent Memory (Extended Version)

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    We present Dinomo, a novel key-value store for disaggregated persistent memory (DPM). Dinomo is the first key-value store for DPM that simultaneously achieves high common-case performance, scalability, and lightweight online reconfiguration. We observe that previously proposed key-value stores for DPM had architectural limitations that prevent them from achieving all three goals simultaneously. Dinomo uses a novel combination of techniques such as ownership partitioning, disaggregated adaptive caching, selective replication, and lock-free and log-free indexing to achieve these goals. Compared to a state-of-the-art DPM key-value store, Dinomo achieves at least 3.8x better throughput on various workloads at scale and higher scalability, while providing fast reconfiguration.Comment: This is an extended version of the full paper to appear in PVLDB 15.13 (VLDB 2023

    Belle II Technical Design Report

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    The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.Comment: Edited by: Z. Dole\v{z}al and S. Un

    Compiling the space shuttle wind tunnel data base: An exercise in technical and managerial innovators

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    Engineers evaluating Space Shuttle flight data and performance results are using a massive data base of wind tunnel test data. A wind tunnel test data base of the magnitude attained is a major accomplishment. The Apollo program spawned an automated wind tunnel data analysis system called SADSAC developed by the Chrysler Space Division. An improved version of this system renamed DATAMAN was used by Chrysler to document analyzed wind tunnel data and data bank the test data in standardized formats. These analysis documents, associated computer graphics and standard formatted data were disseminated nationwide to the Shuttle technical community. These outputs became the basis for substantiating and certifying the flight worthiness of the Space Shuttle and for improving future designs. As an aid to future programs this paper documents the lessons learned in compiling the massive wind tunnel test data base for developing the Space Shuttle. In particular, innovative managerial and technical concepts evolved in the course of conceiving and developing this successful DATAMAN system and the methods and organization for applying the system are presented

    Analysis of a district energy system containing thermal energy storage and heat pumps

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    Tese de mestrado integrado em Engenharia da Energia e do Ambiente, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2017No contexto de atingir as metas estabelecidas até 2050 para a redução da emissão de gases de efeito de estufa, as redes urbanas de energia são já consideradas uma solução provada. Isto deve-se essencialmente ao facto de estas possibilitarem recuperar energia que seria de outra forma desperdiçada. Para além disso, possibilitam a integração de diferentes fontes de energia renovável, ou outras tecnologias, como é o caso de armazenamento térmico de energia. Quando presente, armazenamento de energia térmica confere maior flexibilidade, bem como maior segurança energética e pode ser usado para otimizar o equipamento responsável pela produção de energia térmica, como por exemplo bombas de calor. O principal objetivo deste projeto é estudar a influência da introdução de armazenamento de energia térmica de curta duração numa rede urbana de energia, em que o abastecimento de calor é suprido por uma combinação de armazenamento de energia térmica sazonal e bombas de calor. Em particular, pretende-se analisar de que forma pode o armazenamento de curta duração, que consiste num tanque de água, ser usado para deslocar a produção de calor (carga térmica), de períodos de cheia ou ponta, para períodos de vazio, e quantificar as consequências desta estratégia (load shifting) na produção de energia térmica e consumo de eletricidade. Para que isto seja possível, o consumo de energia relacionado com aquecimento e arrefecimento de um grupo de edifícios é determinado usando um modelo implementado em Modelica, e a análise dos sistemas de energia é feita através de um modelo analítico, implementado em Matlab. Os resultados obtidos mostram que a introdução de armazenamento térmico de curto prazo, permitiu deslocar parte da carga térmica de períodos de pico, para períodos de vazio. Isto levou a uma redução significativa (11.5% a 37.5%) nos custos individuais de eletricidade para os consumidores de calor, que foram determinados com base nos preços de mercado de eletricidade holandês (EPEX), e em tarifas de distribuição e transmissão. Paralelamente, verificou-se um aumento na produção total de calor (~ 7%), principalmente devido a maiores perdas térmicas face ao sistema sem armazenamento de curta duração. No entanto, a eficiência global das bombas de calor (COP) também aumentou (~ 14%), o que resultou ainda assim num menor consumo global de eletricidade (~ -13%), apesar da maior produção de energia.In the context of meeting the targets set by 2050 for reducing greenhouse gas emissions, District Energy (DE) systems are considered to be a proven solution. This is essentially due to their ability to re-use energy that would otherwise be wasted, and its compatibility with a variety of other technologies, such as Thermal Energy Storage (TES) and renewable energy sources. When available, thermal energy storage provides greater flexibility, reliability, as well as energy security and it can be used to optimize equipment responsible for thermal energy production, as for instance, heat pumps. The main objective of this project is to study the influence of the introduction of short-term thermal storage in a DE, where heat and cold requirements are supplied by a combination of seasonal TES and heat pumps. To be specific, the focus is to analyze to what extent can short-term TES be used to shift the heat pumps electrical heating loads, from peak to off-peak periods, and quantify the influence of this strategy on energy production and electricity consumption. In order to do this, space heating and cooling demand data regarding a group of buildings is determined in Dymola/Modelica, and the energy systems performance is evaluated by using an analytical MATLAB model. The results obtained show that the introduction of short-term storage allowed to shift some of the thermal load from peak to off-peak periods. This operation led to a significant reduction in the individual electricity costs for the heat consumers (11.5% to 37.5%), which were determined based on electricity prices from the Dutch EPEX day-ahead spot market. Regarding electricity consumption and total heat production, it was noticed that the introduction of short-term storage led to an increase in the total heat output from heat pumps (~7%), mainly due to higher thermal losses. However, the global heat pumps coefficient of performance (COP) also increased (~14%), which resulted in less electricity consumption (~-13%), despite of the higher heat production

    A Practical Distributed Spectrum Sensing System

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    As the demand for wireless communication systems grows, the need for spectrum grows accordingly. However, a large portion of the usable spectrum has already been exclusively licensed to various entities. This exclusive allocation method encourages spectrum to be left unused if the licensee has no need for that spectrum. In order to better utilize spectrum and formulate new approaches for greater spectrum use efficiency, it is imperative to possess a thorough understanding about how wireless spectrum behaves over time, frequency, and space. In this thesis, a practical, scalable, and low-cost wideband distributed spectrum sensing system is designed, implemented, and tested. The proposed system is made up of a collection of nodes that use general purpose, off-the-shelf computer hardware as well as a collection of inexpensive software-defined radio (SDR) equipment in order to collect and analyze spectrum data that varies across time, frequency, and space. The spectrum data the proposed system collects is the power present at a given frequency. The tools needed to analyze the gathered data are also created, including a periodogram and spectrogram function, which visualize average spectrum use over a period of time and as spectrum use varies with time, respectively. The proposed system also facilitates the testing of a spatio-spectrum characterization method using real data. This method has only been simulated up to this point. The characterization technique allows for spatially varying spectrum measurements to be visualized using heat maps
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