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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.
341

RANS and DES computations for a three-dimensional wing with ice accretion

Mogili, Prasad. January 2004 (has links)
Thesis (M.S.) -- Mississippi State University. Department of Aerospace Engineering. / Title from title screen. Includes bibliographical references.
342

CAS, interdiction, and attack helicopters

Groenke, Andrew S. January 2005 (has links) (PDF)
Thesis (M.A.)--Naval Postgraduate School, 2005. / Title from title screen (viewed Jan. 31, 2006). "June 2005." Includes bibliographical references (p. 63-67). Also issued in paper format.
343

CAS, interdiction, and attack helicopters /

Groenke, Andrew S. January 2005 (has links) (PDF)
Thesis (M.A. in National Security Affairs)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Daniel Moran. Includes bibliographical references (p. 63-67). Also available online.
344

Then and now a comparsion of the attacks of December 7, 1941 and September 11, 2001 as seen in the New York Times with an analysis of the construction of the current threat to the National Security /

Williams, Todd Austin. January 2003 (has links)
Thesis (M.A.)--Ohio University, June, 2003. / Title from PDF t.p. Includes bibliographical references (leaves 85-88)
345

Comportamento macro e microestrutural de barreiras compactadas para contenção de lixiviados ácidos de resíduos industriais e de mineração

Korf, Eduardo Pavan January 2014 (has links)
A lixiviação de resíduos industriais e de mineração usualmente resultam em águas residuárias com pH extremamente ácido. Estes contaminantes podem migrar para o solo ou percolar através de barreiras de fundo em aterros de resíduos sólidos, perturbando a estrutura do solo e modificando a sua condutividade hidráulica. A adição de cimento Portland a este tipo de barreira pode ser uma opção para a neutralização do pH, buscando reduzir os impactos da lixiviação ácida nas águas subterrâneas. Embora muitos estudos abordem o comportamento de barreiras compactadas quando submetidas à ação dos mais diversos tipos de contaminantes, poucos tem explorado os aspectos microestruturais dos materiais componentes das barreiras e suas modificações ao longo do processo de percolação do contaminante. Neste contexto, este trabalho propôs a avaliação do comportamento microestrutural e macroestrutural de um solo argiloso residual compactado, com e sem a adição de cimento Portland (0, 1 e 2%), para fins de aplicação em barreiras impermeáveis sumetidas à ação de lixiviados ácidos. Os resultados motraram uma notável redução da condutividade hidráulica com a percolação de uma solução a 2% de ácido sulfúrico, a qual foi acompanhada pela ocorrência de recalques e redução do pH. Com relação à análise do tamanho e distribuição dos poros, pôde-se concluir que tanto a adição de cimento como a variação do peso específico de compactação, aliadas à ocorrência de recalques, contribuíram para a redução dos microporos e a consequente redução da condutividade hidráulica. Com relação às modificações químicas e mineralógicas, o ataque ácido promoveu principalmente a solubilização de Fe2O3 nas camadas superiores das amostras ensaiadas, porém não causou alterações significativas na estrutura dos argilominerais. Pode-se inferir que o peso específico de compactação não influenciou os resultados e que a adição de cimento contribuiu de maneira discreta para reduzir o impacto da percolação ácida, na medida em que produziu compostos de Ca e S nas camadas de meio e inferior das amostras, reduziu os microporos e retardou a solubilização de Fe2O3, a qual ocorreu principalmente nas camadas superiores das amostras ensaiadas. / The leaching of industrial and mining solid wastes usually result in wastewaters with extremely acidic pH, which might percolate into the ground or through bottom compacted barriers of landfills, disturbing soil structure and increasing hydraulic conductivity. The addition of Portland cement to containment barriers can be an option for pH neutralization, seeking to reduce the impact of acidic leachate to the groundwater. Although many studies have addressed the behavior of compacted barriers subjected to the action of several types of contaminants, a few have explored the microstructural aspects of barriers component materials and their modifications along the contaminant percolation process. In this context, this work proposed the evaluation of microstructural and macrostructural behavior of a compacted residual clayey soil, with and without the addition of Portland cement (0, 1, and 2%), for purposes of application in containment bottom submitted to acidic leachate percolation. The results showed a noticeable reduction in the compacted soil hydraulic conductivity during the percolation of a 2% sulfuric acid solution, which was accompanied by settlements and pH reduction. Regarding the determination of the size and distribution of pores, it can be concluded that both the addition of cement and the variation of specific weights, coupled with the occurrence of settlements, contributed to the reduction of micropores, which consequently resulted in hydraulic conductivity reduction. Concerning the chemical and mineralogical changes, the acidic attack mainly promoted the solubilization of Fe2O3 in the upper layers of the specimens tested but caused no significant modification in clay minerals structure. It can be inferred that the specific gravity did not influence the results and that the cement addition contributed discretely to reduce the acidic percolation impact, as it produced compounds of Ca and S in the middle and lower layers, reduced micropores, and slowly delayed Fe2O3 solubilization, which occurred mainly in the upper layers of the specimens tested.
346

Comparação de respotas funcionais de duas espécie de peixes píscivoras / Comparison of functional responses of fish species of two piscivores

Carvalho, Thiago Lima de Carvalho 22 February 2016 (has links)
Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-03-20T15:42:34Z No. of bitstreams: 1 ThiagoLC_DISSERT.pdf: 1446311 bytes, checksum: f9df761557b8cd9c1f4395f10697bdbd (MD5) / Made available in DSpace on 2017-03-20T15:42:35Z (GMT). No. of bitstreams: 1 ThiagoLC_DISSERT.pdf: 1446311 bytes, checksum: f9df761557b8cd9c1f4395f10697bdbd (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Species of the Cichla genus have been introduced in a variety of tropical aquatic ecosystems, thus resulting in a marked reduction in diversity and population size of native fish assemblies due to their predatory behavior. Despite Cichla induced impact the mechanisms by which the species are still poorly known. In this study we compared the functional response of an alien predator fish C. kelberi and a native predator H. aff. malabaricus. More specifically, the tested hypotheses were: 1) both predator species have functional responses of type II on different prey species, and 2) the functional responses of the alien predator were higher for all preys when compared to the native predator. The predators were acclimated in tanks of 500 liters and fed twice daily with preys O. niloticus and L.vannamei for 3 days, 4 preys in the morning and 4 in the afternoon. Hunger levels were standardized after a fast of 48 hours. After the pre-experimental phase an exemplar of C. kelberi was randomly introduced in each tank of O. niloticus with initial prey densities of 2, 4, 8, 16, 25 and 40, and for L. vannamei 2, 4, 8, 16, 32 and 64 (n = 4 per density). After 24 hours the number of prey consumed was counted. This method was repeated for the native predator H. aff. malabaricus. Totaling 48 experimental units. The functional response C. kelberi was greater than or equivalent to the native predator H. aff. malabaricus. There was no difference in consumption between the two species at low densities. The attack rate did not differ between the two predators and handling time was driven by C. kelberi for the species O. niloticus. However, the two species showed functional response type II, thus corroborating with the comparative functional response method to predict the impact on native communities. Functional Comparative Response is a quick and reliable method to predict the ecological impacts of invasive species / Espécies do gênero Cichla têm sido introduzidas em vários ecossistemas aquáticos tropicais, resultando em uma redução na diversidade e tamanho populacional de assembleias de peixes nativos, devido a sua atuação predatória. Os mecanismos de predação pelos quais o tucunaré (Cichla kelberi) permanece pouco conhecido. Nesse estudo foram comparadas as resposta funcionais de um peixe predador alienígena C. kelberi e de um predador nativo Hoplias aff. malabaricus. Especificamente, foram testadas as hipóteses: 1) que ambas as espécies de predador apresentam respostas funcionais do Tipo II, na qual a espécie preda em baixa densidade, sobre diferentes espécies de presas, e que 2) as respostas funcionais do predador alienígena foram maiores para todas as presas, quando comparados com o predador nativo. Os predadores foram aclimatados nos tanques de 500 litros e alimentados duas vezes ao dia com alevinos de Oreochromis niloticus e Litopenaeus vannamei durante 3 dias, 4 presas pela manhã e 4 presas a tarde. Os níveis de fome foram padronizados depois de um jejum de 48 horas. Foi introduzido aleatoriamente um exemplar de C. kelberi em cada tanque de O. niloticus com densidades iniciais de presas de 2, 4, 8, 16, 25 e 40 e para L. vannamei 2, 4, 8, 16, 32 e 64 (n = 4 por densidade), e depois de 24 horas contabilizado o número de presas consumidas. Este método foi repetido para o predador nativo H. aff. malabaricus. Totalizando 48 unidades experimentais. A resposta funcional de C, kelberi foi maior ou equivalente a do predador nativo H. aff. malabaricus. Não houve diferença no consumo entre as duas espécies nas baixas densidades. A taxa de ataque não diferenciou entre os dois predadores e o tempo de manipulação foi impulsionado por C, kelberi para a espécie O. niloticus. As duas espécies apresentaram resposta funcional do tipo II corroborando com o método de resposta funcional comparativa de prever os impactos nas comunidades nativas. Respostas funcionais é um método rápido e confiável para previsão de impactos ecológicos de espécies invasoras / 2017-03-20
347

Vývoj a působení teroristických skupin s ohledem na situaci po roce 2001 / Development and operation of terorist groups with regard to the situation after 2001

LIŠKA, Jaroslav January 2016 (has links)
Terrorism is a very complex and ever developing phenomenon, which can be construed as systematic use of organised violence against uninvolved persons for the purpose of achieving political, criminal or other goals. The struggle against it is very complicated, but necessary. Currently, many people especially connect this term with the Islamic religion. Islamic radicals justify the performed terrorist attacks by an extreme perception of the holy book of Quran and proclaim themselves as holy fighters for freedom. However, recent years have shown that terrorism has spread throughout the world and now with the mass migration represents one of the largest threats for today's society. Terrorism develops as fast as our society and prides itself with the ever growing popularity with sponsors of various kinds with different interests, who with their considerable not only financial support allow the terrorist groups to commit more and more sophisticated and destructive attacks. From the perspective of the CR it can be said that our state can fortunately be considered relatively safe, unlike other member countries of the EU. However, it is necessary to take into account the participation of the CR in the international antiterrorist operations, which without question make the CR a potential target of a possible terrorist attack. However, the participation in these missions is necessary. The currently largest terrorist group Islamic State included the Czech Republic in its list of the "crusade coalition" at the end of 2015, where all enemies of this "pseudo-state". The theoretical part of the thesis on the topic of the Development and action of terrorist groups with regard to the situation after 2001 especially deals with the issues of Islamic terrorist groups. In the introduction of the thesis, the fundamental terms of the issues in question, such as terrorism, Islam, jihad, Islamism, Islamic fundamentalism. The second part of the theoretical part of the thesis deals with terrorist organisations. Due to the current safety situation, the main attention was attached to the development and activity of major terrorist groups, that is Hezbollah, Hamas, and of course Al-Qaeda and the Islamic State. These selected terrorist organisations are elucidated in the theses as much as possible, including their leaders. Subsequently, further selected terrorist organisations are linked to these terrorist groups, namely Al-Gama'a al-Islamiyya, Palestine Islamic Jihad, and Taliban. In the initial chapter of the research part of the thesis, a research question is stated, which has been determined as follows: "What is the threat of a terrorist attack in the territory of the Czech Republic?", which directly follows the goal of the thesis, which was stipulated as: "Assessment of the threat of a terrorist attack in the territory of the Czech Republic depending on the development of the terrorist groups." Furthermore, the research methodology is stated. In the following chapter of the research part with the title "Results", the reader first familiarises himself with the largest terrorist attacks so far, which have taken place in the USA, on 11 September 2001 and were a turning point in the history of terrorism. The last pages of this part of the thesis contemplate the attacks of Islamic radicals and the situation in the West after 11 September 2001. The middle part of this chapter familiarises the reader with the threats of terrorism for the CR with an accent on Islamic terrorism. Attention is also paid to the Muslim community living in the CR and EU as a potential risk factor of a possible attack. The last part of this chapter of the thesis states semi-structured interviews, which were conducted with leading experts in the issues of terrorism. In the final chapter with the title "Discussion", an analysis of the examined areas is performed. In the conclusion of the thesis, the research question and the thesis objective are answered.
348

Comparação entre forças propulsivas efetivas calculadas e medida durante um palmateio de sustentação / Comparison between calculated and measured effective propulsive forces during a support sculling motion

Gomes, Lara Elena January 2010 (has links)
A força propulsiva gerada durante o palmateio é resultado do somatório das forças de arrasto e de sustentação, sendo que a componente que atua na direção do movimento desejado é igual à força propulsiva efetiva. Essas forças podem ser estimadas a partir de equações hidrodinâmicas, porém essas equações não consideram todos os mecanismos que contribuem para a propulsão. Dessa forma, o objetivo geral do presente estudo foi comparar a força propulsiva efetiva calculada a partir das equações hidrodinâmicas e a força propulsiva efetiva medida durante o palmateio de sustentação (na posição vertical, de cabeça para cima) em cada fase do palmateio. Para isso, uma praticante de nado sincronizado realizou palmateio na posição vertical de cabeça para cima durante 15 segundos, enquanto que dados cinemáticos e cinéticos foram obtidos por viodeogrametria 3D e dinamometria respectivamente. A análise gráfica de Bland e Altman foi usada para comparar as forças propulsivas efetivas medida e calculada durante o palmateio. As forças propulsivas efetivas calculada e medida foram diferentes, sendo a medida maior que a calculada. Ainda, os resultados indicaram que o palmateio executado não foi simétrico, isto é, a orientação e a força propulsiva entre a mão direita e a esquerda foram diferentes. Portanto, o achado do presente trabalho destaca a importância de mecanismos instáveis para a propulsão durante o palmateio, já que as forças estimadas por meio das equações hidrodinâmicas apresentaram resultados inferiores, sendo isso observado ao longo de todo o palmateio. / Propulsive force generated during sculling motion results from drag and lift propulsive forces, and the component acting in the direction of motion is the effective propulsive force. These forces may be calculated using hydrodynamic equations, but these equations do not consider all mechanisms that contribute to the propulsion. Thus, the main purpose of this study was to compare the calculated effective propulsive force using the hydrodynamic equations and the measured effective propulsive force during a support sculling motion (vertical position with the head above the water‟s surface) in each phase of sculling. For this, a practitioner of synchronized swimming performed sculling motion in a vertical position with the head above the water‟s surface during 15 seconds, while kinematic and kinetic data were obtained by 3D videogrammetry and dynamometry respectively. Graphical techniques from Bland and Altman were used to compare the measured effective propulsive force and calculated effective propulsive force during sculling motion. The calculated effective propulsive force and the measured effective propulsive force were different, the measured being greater than the calculated. Moreover, the results indicated sculling motion performed was not symmetric, that is, the orientation and propulsive forces between the right and left hands were different. Therefore, the result of this study highlights the importance of the unsteady mechanisms for the propulsion during sculling motion, because the calculated forces using the hydrodynamic equations presented low values throughout the sculling motion.
349

Miroirs, Cubes et Feistel Dissymétriques / Mirrors, cubes and unbalanced Feistel schemes

Volte, Emmanuel 28 November 2014 (has links)
La première partie est consacrée à l'étude d'attaques génériques sur des schémas de Feistel dissymétriques. Ces attaques sont en fait des distingueurs qui calculent sur une partie des clairs-chiffrés le nombre de paires vérifiant un système d'égalités et de non-égalités sur un groupe fini. La recherche de ce type d'attaques a été automatisée et améliorée, notamment en tenant compte de goulots d'étranglement. Plus généralement, des travaux sur ce type de systèmes, que l'on désigne par les termes << théorie du miroir >> sont exposés dans cette partie. En particulier, on décrit le problème de la somme de deux bijections sur un groupe fini.La deuxième partie décrit un des candidats à la compétition SHA-3 : la fonction de hachage CRUNCH. Cette fonction reprend un schéma de Feistel dissymétrique et utilise la somme de deux bijections. De plus, un nouveau mode d'enchaînement a été utilisé.Dans la dernière partie on traite de problème d'authentification à divulgation nulle de connaissance. D'abord avec les polynômes à plusieurs variables, puis avec un problème difficile lié aux groupes symétriques. Une illustration est donnée avec le groupe du Rubik's Cube.Enfin une méthode originale pour tenter de trouver une solution aux équations de Brent est donnée en annexe. / The first part is dedicated to the study of generic attacks in unbalanced Feistel schemes. All these attacks are distinguishers that counts how many number of couples (plain text, cipher text) verify a system of equalities and non-equalities on a finite groupe. With the help of algorithms we have found all the possible attacks, and some attacks with a neck bottle have been rejected automatically. More generally, we describe some works about the "mirror theory" that deals about that kind of systems. We specially describe the problem of the sum of two bijections in a finite group.The second part describes one of the candidate of the SHA-3 competition : the hash function called CRUNCH. This function includes the sum of two bijections, and each bijection is an unbalanced Feistel Scheme. A new chaining process for long messages is given.In the last part we deal with zero-knowledge authentication problems. The first protocol is based on multivariate polynomials. The second is linked to a difficult problem in symmetric groups. We take the example of the Rubik's cube group.Finally, we reveal some works on Brent equations. We build an algorithm that may find one solution.
350

Cyberkonflikten i Ukraina : Cyberattacker som instrument i tvingande diplomati

Kolli, Johanna January 2018 (has links)
This paper aims to describe and explain the Russian use of cyberattacks in the Ukrainian conflict. Two major cyber events, BlackEnergy in 2015 and NotPetya in 2017, are analysed by the theoretical framework of coercive diplomacy developed by Daniel Byman and Matthew Waxman, as well as the theory of cyber coercion made by Daniel R. Flemming and Neil C. Rowe. This paper concludes that the Russian use of cyberattacks could be understood as an extension of their already widespread practice of coercive diplomacy as a foreign policy tool. The cyberattacks were developed to pressure the Ukrainian energy and economic sector, through destabilisation of the economic powerbase and the country as a whole. The cyber offenses are developed to push the Ukrainian politics from western influence back towards the Russian political orbit. This due to the political, economic, and power interests Russia finds in the post-soviet state of Ukraine.

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