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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.
21

Integration of Special Sensor Microwave/Imager (SSM/I) and in Situ Data for Snow Studies from Space

Sun, Changyi 01 May 1996 (has links)
The Special Sensor Microwave/Imager (SSM/I) radiometer is a useful tool for monitoring snow conditions and estimating snow water equivalent and wetness because it is sensitive to the changes in the physical and dielectric properties of snow. Development and improvement of SSM/I snow-related algorithms is hampered generally by the lack of quantitative snow wetness data and the restriction of a fixed uniform footprint. Currently, there is a need for snow classification algorithms for terrain where forests overlie snow cover. A field experiment was conducted to examine the relationship between snow wetness and meteorological variables. Based on the relationship, snow wetness was estimated concurrently with SSM/I local crossing time at selected footprints to develop an SSM/I snow wetness algorithm. For the improvement of existing algorithms, SSM/I observations were linked with concurrent ground-based snow data over a study area containing both sparse- and medium-vegetated regions. Unsupervised cluster analysis was applied to separate SSM/I brightness temperature (Tb) data into groups. Six typical SSM/I Tb signatures, based on cluster means of desired snow classes, were identified. An artificial neural network (ANN) classifier was designed to learn the typical Tb patterns Ill for land-surface snow cover classification. An ANN approximator was trained with the relations between inputs of SSM/I Tb observations and outputs of ground-based snow water equivalent and wetness. Results indicated that snow wetness estimated from concurrent air temperature could provide the ground-based data needed for the development of SSM/I algorithms. The use of cluster means might be sufficient in ANN supervised learning for snow classification, and the ANN has the potential to be trained for retrieving different snow parameters simultaneously from SSM/I data. It is concluded that the ANN approach may overcome the drawbacks and limitations of the existing SSM/I algorithms for land-surface snow classification and parameter estimation over varied terrain. This study demonstrated a nonlinear retrieval method towards making the inferences of snow conditions and parameters from SSM/I data over varied terrain operational.
22

Une architecture de communication pour environnements virtuels distribués à grande échelle basée sur les canaux multipoint

Barza, Laurentiu 02 July 2004 (has links) (PDF)
Le sujet de la thèse est situé à la confluence du IP multicast et des environnements virtuelles. La thèse présente l'élaboration, l'implémentation et les expérimentations d'une architecture de communication pour une application d'environnement virtuel à grande échelle. Le but de cette architecture est de permettre à un grand nombre de participants, situés dans un monde virtuel, de communiquer entre eux (chaque participant communique seulement avec ses voisins), à travers différent s flux de données (vidéo, audio, texte). Dans la conception de cette architecture nous avons considéré les objectifs suivants : minimiser le trafic dans le réseau, permettre à un très grand nombre de participants d'être connectés simultanément dans le inonde virtuel, accepter des participants avec des capacités très différentes, donner à chacun d'entre eux la possibilité de Communiquer selon ses capacités et de prendre en compte les contraintes des temps réel spécifique à des flux multimédia. Nous utilisons le multipoint comme moyen de communication de groupe et en particulier les aspects contrôle de congestion afin de réduire le trafic dans le réseau. Un modèle simplifié de multipoint ayant été proposé à l'IETF (le modèle SSM ou Source Spécifique Multicast), nous avons choisi de l'utiliser dans notre architecture, à cause du fait qu'il était mieux adapté pour exprimer les différentes préférences des participants. Pour réaliser la communication dans des mondes virtuels, nous avons défini une architecture composée de deux nivelles de filtrage des données. Au premier niveau de filtrage, le monde virtuel est dynamiquement découpé en zones selon la densité de participants dans le monde. Un participant connait tous les autres participants présents dans sa zone. Au deuxième niveau de filtrage, le participant calcule ses voisins dans le monde virtuel et commence a communiquer avec eux selon leurs Capacités. Un participant peut transmettre des différents flux des données. Chaque flux est envoyé sur un canal SSM différent. Les expériences réalisées ont démontré la faisabilité et les performances de notre architecture comparent aux autres architectures proposées dans la littérature. On a intégré le module de communication proposé dans V-Eye, une application de monde virtuel développée par le projet Planète.
23

Radiométrie micro-onde de la neige : interprétation de données satellitaires sur l'Antarctique : expérimentations dans les Alpes

Sherjal, Isabelle 23 June 1995 (has links) (PDF)
L'objectif des études en télédétection au Laboratoire de Glaciologie et de Géophysique de l'Environnement est de pouvoir mesurer de l'espace les paramètres géophysiques importants caractérisant la surface des calottes polaires, tels que les zones de fonte, la température et l'accumulation de neige. De plus, les mesures satellitaires dans le domaine des micro-ondes offrent l'avantage d'être peu sensibles aux effets atmosphériques et de fournir des informations sur une épaisseur du manteau neigeux de quelques centimètres à plusieurs mètres. Un modèle semi-empirique basé sur le transfert radiatif et un modèle thermodynamique simple ont permis, moyennant l'hypothèse d'une émissivité constante et l'ajustement du coefficient d'extinction dans le milieu, de reconstruire les températures de brillance mesurées par le satellite (données SSM/I), à partir des seules températures de l'air dont nous disposions. Cette méthode a été testée sur deux sites d'Antarctique présentant des caractéristiques de neige différentes. Ce modèle a ensuite été inversé de façon à déterminer la température de surface de la neige à partir des mesures satellitaires. Le problème est actuellement sous déterminé, cependant les résultats sont prometteurs. De manière à valider les modèles, nous avons acquis simultanément, en un site glaciaire du massif du Mont-Blanc, des mesures radiométriques à plusieurs fréquences et angles d'incidence, avec le radiomètre PORTOS du CNES, fixé à une télécabine, et des mesures des caractéristiques du manteau neigeux. Ces mesures ont été étalonnées, corrigées de l'angle local d'incidence, l'effet du diagramme d'antenne sur la mesure angulaire a été évalué. Elles ont alors été comparées aux valeurs simulées par un modèle d'émissivité de la neige pour un milieu uniforme et stratifié et à un modèle de transfert radiatif. Les problèmes de caractérisation de la structure de la neige pour les micro-ondes et de modélisation de la diffusion par les cristaux ont été soulevés.
24

Ytterliggare antaganden om modern sjöstrid

Ramel Kjellgren, Jim January 2013 (has links)
Denna uppsats undersöker huruvida vi med hjälp av Gustav von Schmalensees modifikation av Lanchesters kvadratiska N2-Law kan bestyrka eller falsifiera teorin att en kustflotta med hjälp av en amfibisk miljö kan slå en på pappret överlägsen motståndare. Den komplexa miljö som en kustremsa eller skärgård utgör påverkar en högsjöflottas kapacitet att utgöra ett hot mot en kustflotta vars taktik är anpassad för terrängen och de synergieffekter som den ger. Uppsatsen försöker påvisa hur stor inverkan variabeln geografi har i sammanhanget. Vidare undersöker uppsatsen huruvida det är möjligt att förbättra von Schmalensees modifikation av Lanchesters N2-Law med hjälp av den faktiska sannolikheten för träff med sjömålsrobot inomskärs respektive utomskärs. Med hjälp av Försvarshögskolans sjökrigsspel Simple Surface Warfare Model (SSM) genomförs ett experiment där teorierna testas empiriskt. Resultaten visar en förbättring i prediceringen av stridsutfall med sjömålsrobot om koefficienten för den faktiska sannolikheten för träff räknas in i ekvationen. Vidare konstateras att en stark korrelation kan ses i en mindre kustflottas överlevnad i amfibisk miljö då de möter en på pappret överlägsen motståndare.
25

Impact of information and communication technologies on charitable organisations in Kuwait

Al-Foudary, Adel K. E. January 2005 (has links)
In many countries, non-profit organisations provide enormous help to the public in the form of services, aid, education, advocacy, and many other humanitarian supports. However, despite the important work of many non-profit organisations in their fields, there has been little research about the role on Information and Communication Technologies (ICTs) in facilitating aid distribution. In an effort to improve understanding of non-profit organisations working in charitable programmes, this research assesses the impact of ICTs in charitable organisations in the State of Kuwait. One of the purposes of this study is to provide guidelines to improve the use of ICTs in order to meet the needs of charities, their donors and beneficiaries, and their ability to comply with state legislation. This research uses a multi-methodology approach, which employs two system methodologies in tackling the research problem. The research methodologies that have been applied are Soft Systems Methodology (SSM) and Effective Technical and Human Implementation of Computer based System (ETHICS). The participants of the research included charities, authorities, staff, beneficiaries, and donors. The results showed that the current services and activities do not meet the needs and satisfaction of the charities, donors, and beneficiaries. The results also showed that the charities fall short in coping with the national and international compliance requirements. Consequently, there is a need for an appropriate change in systems and procedures, which include database system, communication, technical, confidentiality and security of donors and beneficiaries, co-operation and coordination, and awareness and attitudes of authorities. The study provides the changes needed to improve the current situation in Kuwaiti charities. As one of these changes, a novel design of a web-based Information Exchange System amongst Kuwaiti Charity Organisations (IESKCO) has been developed. This web-based system will combine all Kuwaiti charitable programmes in to one appropriate system, which offers the highest level of benefits at the lowest cost for their clients. In order to ensure that this new system meets the users' needs, an empirical evaluation method has been chosen to evaluate the IESKCO prototype. The results revealed that the users' needs are met using the application. This research has also led to conclusions and directions for further research on the impact of ICTs in charitable sectors.
26

Analýza herní komunity pomocí metodologie měkkých systémů / Analysis of gaming community using Soft System Methodology

Hurych, Jan January 2015 (has links)
This diploma thesis aims to analyse virtual gaming community and it's problems in case of community belonging to EU server of the game called World of Tanks. To solve these problems, Soft System Methodology by P. Checkland, is used. The thesis includes analysis of significance of gaming communities for the gaming industry as a whole. Gaming community is then defined as a soft system. There are 3 problems analysed in the practical part of the thesis using newer version of SSM. One iteration of learning cycle of this methodology is used to solve every single one of the presented problems. Problems are chosen by players using questionnaire. At the end, application of the SSM is evaluated for the domain of gaming communities in general and problems with its application are presented.
27

Projeto e construção de equipamento eletromagnetico para a produção de materia-prima para tixoconformação de ligas metalicas / Design and development of an electromagnectic equipment for the production of raw material for thixoforming of metal alIoy

Bubenik, Rubens Luiz 18 May 1998 (has links)
Orientador: Maria Helena Robert / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-23T20:58:55Z (GMT). No. of bitstreams: 1 Bubenik_RubensLuiz_M.pdf: 9820006 bytes, checksum: 74e4259834492d5dafe6eb6b382dbc4f (MD5) Previous issue date: 1998 / Resumo: Este trabalho trata do projeto e construção de um equipamento capaz de alterar a morfologia da fase primária de ligas metálicas em solidificação, diferenciando-a das estruturas dendríticas produzidas na solidificação convencional. Neste processo uma força externa provoca movimentos no metal líquido com objetivo de alterar a morfologia de crescimento do sólido, resultando em estruturas pré-reofundidas. No equipamento idealizado é utilizado um campo magnético girante para fornecer a força necessária ao movimento. O trabalho envolve projeto, construção e montagem de circuitos elétricos, circuitos eletrônicos e dispositivos mecânicos, bem como testes de eficiência do equipamento na produção de estruturas pré-reofundidas da liga AA 2011. Para testes foram variados o tempo de agitação do líquido (230 e 300 s), e o modo de agitação (normal e com reversão), sendo mantidas constantes a potência (1040 W) e a taxa de resmamento ('20 GRAUS¿/min.). Os resultados obtidos atestam a eficiência do equipamento na obtenção de lingotes com macroestrutura equiaxial refinada, homogênea em todo o seu volume, e microestrutura apresentando dendritas fragmentadas, com fator de forma de 2 a 3 para todas as condições analisadas. Estes valores de fator de forma podem ser considerados excelentes para materiais a serem utilizados como matéria prima para a conformação no estado pastoso reofundido / Abstract: This work relates the design and development of an equipment capable of modifying the morphology of primary phase during solidification of metal alloys, differentiating such structures ftom those dendritic obtained in conventional solidification. In this process turbulence is imposed to the liquid metal by means of a external force with the purpose of modifying the morphology of the growing solid, resulting in pre-rheocast structures. In the idealized equipment a rotating magnetic field is used to provide the necessary stirring in the Liquid. This work involves design, building and assembling of the equipment, as well as preliminarytests to analyse the efficiency of the equipment to produce ingots of the alloy AA 2011 with pre-rheocast structures. Different stirring times (230 and 330 s) and type of movement (normal or reverted) were utilized in the tests, while power and freezing rate in the material were kept constant (1040 W and '20 DEGREES¿/min., respectively). Results showed the efficiency of the designed equipment in the production of ingots with fine, equiaxial and homogeneous macrostructure and microstructures presenting highly ftagmented dendrites, with values of morphology index varying ftom 2 to 3 for all operational conditions tested. Those values of morphology index can be considered excellent for a material to be utilized as raw material for forming in the semi-solid state or thixoforming / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
28

Implementace real-time protokolu / Real-time protocol implementation

Procházka, Jan January 2009 (has links)
Thesis deals with multicast broadcasts, discusses the type of ASM and SSM. Also deals with the principle of RTP / RTCP protocol for large multicast groups, for example, broadcasting IPTV. It was created a model for simulating the behavior of the network load in a large number of receivers. The application was developed in Java and uses the recommendations of RFC3550. There are also analysed processes of communication, initialization, log out, the structure of the data packets and signaling packets. The system is designed that can simulate multicast network and obtain the estimated parameters of the operation, or can operate in real traffic, for example, as a third-party monitor. In both modes, the measurement was carried out model situations. The results of the measurements were then compared. Principle and system control was described in detail. Output measurements are graphically processed and included in the work.
29

Synergizing Systems : Using SSM in prototypical system development

Zafar, Ali, Svensson, Oscar January 2020 (has links)
This thesis is concerned with a research project conducted with a Swedish company to provide recommendations for developing a prototypical information system for the company. The system’s goal was to consolidate data regarding the company’s supply chain and packaging conditions in order to find improvements in packaging development. The thesis employed the use of Soft Systems Methodology to aid with the system development process. A qualitative explorative study was designed for this purpose. Soft Systems Methodology was used after exploring alternative methodologies. This was chosen as the researchers found it important to engage the case company in the system development process. Four semi-structured interviews and two workshops with the relevant officials were the main methods of collecting data. Models such as a rich picture, CATWOE and PQR formula were utilized during the research to visualize important aspects of the system development process. As a result of the research, the researchers were able to provide the company with recommendations for how to further proceed with the development process. Another result of the study was that Soft Systems Methodology was able to unlock tacit information. The methodology also allowed for a consideration of the implementation of an iterative process to support the development. The results of this research suggest that introducing and making use of Soft Systems Methodology is very stimulating in an environment not already using it. The research provided insights needed for progress towards a successful implementation of a new information system, and contributes a real-world SSM case in a corporate environment. The researchers also suggest future opportunities for research that could further build on the work presented in the thesis.
30

Standardiserad tidsplanering för SSM i produktionen / Standardized time scheduling for SSM in production

Tahan, Annabel, Al-kazaz, Haydar January 2019 (has links)
Det här examensarbetet har utförts åt företaget SSM där syftet var att standardisera deras tidsplaner och arbetssätt kring planering i produktionen.   Detta arbete har grundat sig på analys av några av SSM:s tidsplaner inom produktion, där dessa har granskats in i minsta detalj. Tre av sex projekt har studerats djupare och författarna har sedan gjort egna standardmallar som baserats på dessa. Utöver detta har även intervjuer/möten hållits med tidsplanerare både inom företaget men även utanför.   Dessa metoder resulterade i slutsatsen att alla platschefer på SSM samt personal på projekteringssidan bör använda sig utav Vico Office i framtiden för att en standardisering av tidsplanerna ska ske. Detta då programmet sparar återanvändbar information från varje projekt som genomförts, vilket på så sätt kan nyttjas i kommande projekt. I programmet finns olika verktyg för hur man väljer att presentera tidsplanen vilka framgår i rapporten.   Efter att ha provat på programmets olika funktioner rekommenderas att företaget använder sig utav det i framtiden då de kan kombinera olika planeringsverktyg samt koppla ihop modellen med bl.a. kostnader, mängder, resurser och tid. Anpassade standardmallar har tagits fram för att förenkla och standardisera tidsplaneringen enligt SSM:s arbetsprocesser. / This thesis has been carried out for the company SSM where the purpose was to standardize their time schedules and also their working methods regarding planning in production.   To achieve this, the thesis has mostly been based on analysis of some of SSM's time schedules in production, where these have been examined in the smallest detail. Three out of six projects have been studied in more depth and the authors have then made their own standard templates based on these. In addition, interviews/meetings have also been held with time planners both within, but also outside the company.   These methods resulted in conclusion that all site managers at SSM and personnel in the design department should use Vico Office in the future in order to standardize the time schedules. This because the program saves reusable information from each project that has been implemented, which can be used in future projects. The program contains various tools, which are stated in the report that allows the user to choose how to present the time schedule.   After trying the different functions of the program, the recommendation is that the company use Vico in the future as they can combine different planning tools and connect the BIM-model with e.g. costs, quantities, resources and time. Custom standard templates have been developed to simplify and standardize time scheduling according to SSM's work processes.

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