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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.
31

C-RAM : en amerikansk akronym eller en svensk förmåga?

Pekkari, Johan January 2009 (has links)
Det här självständiga arbetet i militärteknik avhandlar huruvida Försvarsmakten, med i huvudsak redan befintlig materiel, genom en teknisk aktiv skyddslösning kan uppnå en förbättrad skyddsförmåga mot indirekt eld. Förmågan som söks är främst avsedd för, men inte begränsad till, att kunna nyttjas för att erhålla ett förbättrat skydd av Försvarsmaktens internationella camper. Därmed utgörs hotbilden framförallt av granatkastarammunition och raketer vilka inom ramen för en teknisk aktiv skyddslösning först måste kunna detekteras för att sen medge förvarning, eller ännu hellre avvärjning, innan de når sitt mål. Arbetets resultat presenteras i form av Förvarsmaktens möjligheter idag tillsammans med en rekommendation om hur skyddsförmågan kan säkerställas på något längre sikt. / This thesis in Military Technology deals with whether the Armed Forces, with mainly pre-existing equipment and using a technical active protection solution, can achieve enhanced protection capability against indirect fire. The capability sought is primarily for, but not limited to, the purpose of obtaining greater protection for the Swedish Armed Forces’ international camps. The threat, typically mortar ammunition and rockets, should within the framework of a technical active protection solution be detectable in order to provide early warning and preferably also interception before reaching its target. The results of the thesis are presented as possibilities for the Swedish Armed Forces today and as recommendations on how this capability can be achieved in the longer term.
32

EXPLORING FACTORS ASSOCIATED WITH ESL/ELD STUDENTS’ PERFORMANCE ON THE ONTARIO SECONDARY SCHOOL LITERACY TEST

ZHENG, YING 12 August 2009 (has links)
The study explored factors associated with English as Second Language (ESL) and English Literacy Development (ELD) students’ performance on the Ontario Secondary School Literacy Test (OSSLT) from three different yet interrelated aspects. These aspects were the relationship between test performance and the characteristics of ESL/ELD students; the relationship between ESL/ELD students’ aggregated school performance and their school-level socio-economic status; and a comparison of ESL/ELD and non-ESL/ELD students’ performance on three test formats in the reading component of the OSSLT (multiple-choice questions, constructed-response questions, and constructed-response questions with explanations). The study was conducted based on 4,311 ESL/ELD students’ test data, their responses to the Educational Quality and Accountability Office’s (EQAO) Student Questionnaire, and the test results of 5,003 non-ESL/ELD students. School-level socio-economic status data from the Education Quality and Indicators Program (EQUIP) were merged with the OSSLT test data. These data were analyzed using exploratory factor analysis, multiple regression and discriminant analysis. The results indicated that e-literacy activities, literature literacy activities, non-fiction literacy activities, newspaper and magazine literacy activities, and literacy hours were positive predictors of ESL/ELD students’ performance on the OSSLT. Letter reading and writing, song and poetry literacy activities were two negative predictors. In terms of home language patterns, whether English was the first language of the test-takers, and what language(s) they spoke at home were both influential variables in differentiating ESL and ELD students’ literacy performance. The results also revealed that a higher parental education index positively predicted a school’s average OSSLT performance. In ii addition, ESL/ELD students demonstrated substantial performance gaps in all of the three test formats in reading as compared to non-ESL/ELD students. Only multiple-choice questions obtained a significant discriminant coefficient with a weak discriminating function. The results of this study offered some insights about identifying and understanding factors that were associated with ESL/ELD students’ OSSLT performance from the perspective of the test-takers and the test itself. The results also provide directions for future research and instructional support in relation to ESL/ ELD students in the context of the accountability framework in Ontario.
33

Modelling Ion Cyclotron Resonance Heating and Fast Wave Current Drive in Tokamaks

Hannan, Abdul January 2013 (has links)
Fast magnetosonic waves in the ion cyclotron range of frequencies have the potential to heat plasma and drive current in a thermonuclear fusion reactor. A code, SELFO-light, has been developed to study the physics of ion cyclotron resonantheating and current drive in thermonuclear fusion reactors. It uses a global full wave solver LION and a new 1D Fokker-Planck solver for the self-consistent calculations of the wave field and the distribution function of ions.In present day tokamak experiments like DIII-D and JET, fast wave damping by ions at higher harmonic cyclotron frequencies is weak compared to future thermonuclear tokamak reactors like DEMO. The strong damping by deuterium, tritium and thermonuclear alpha-particles and the large Doppler width of fast alpha-particles in DEMO makes it difficult to drive the current when harmonic resonance layers of these ionspecies are located at low field side of the magnetic axis. At higher harmonic frequencies the possibility of fast wave current drive diminishes due to the overlapping of alpha-particle harmonic resonance layers. Narrow frequency bands suitable for the fast wave current drive in DEMO have been identified at lower harmonics of the alpha-particles. For these frequencies the effect of formation of high-energy tails in the distribution function of majority and minority ion species on the current drive have been studied. Some of these frequencies are found to provide efficient ion heating in the start up phase of DEMO. The spectrum where efficient current drive can be obtained is restricted due to weak electron damping at lower toroidal mode numbers and strong trapped electron damping at higher toroidal mode numbers. The width of toroidal mode spectra for which efficient current drive can be obtained have been identified, which has important implications for the antenna design. / <p>QC 20130327</p>
34

Algebraické podstruktury v Cm / Algebraic Substructures in Cm

Kala, Vítězslav January 2013 (has links)
Title: Algebraic Substructures in ℂ Author: Vítězslav Kala Department: Department of Algebra Supervisor: Prof. RNDr. Tomáš Kepka, DrSc., Department of Algebra Abstract: We study the structure of finitely generated semirings, parasemifields and other algebraic structures, developing and applying tools based on the geom- etry of algebraic substructures of the Euclidean space ℂ . To a parasemifield which is finitely generated as a semiring we attach a certain subsemigroup of the semigroup ℕ0 (defined using elements such that + = for some ∈ and ∈ ℕ). Algebraic and geometric properties of carry important structural information about ; we use them to show that if a parasemifield is 2-generated as a semiring, then it is additively idempotent. We also provide a ring-theoretic reformulation of this conjecture in the case of -generated semirings. We also classify all additively idempotent parasemifields which are finitely gen- erated as semirings by using the fact that they correspond to certain finitely generated unital lattice ordered groups. Busaniche, Cabrer, and Mundici [4] re- cently classified these using the combinatorial and geometric notion of a stellar sequence which is a sequences of certain simplicial complexes in [0, 1] . We use their results to prove that each such parasemifield is a finite product of...
35

Método variacional de Bogoliubov Aplicado a modelos de Spins: Ising e Blume-Capel

Brito , Rejane Alves de 03 March 2017 (has links)
Submitted by Leonardo Cavalcante (leo.ocavalcante@gmail.com) on 2018-04-30T14:54:08Z No. of bitstreams: 1 Arquivototal.pdf: 981715 bytes, checksum: 76897646d0930b35e6a38674ac2d9ec2 (MD5) / Made available in DSpace on 2018-04-30T14:54:08Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 981715 bytes, checksum: 76897646d0930b35e6a38674ac2d9ec2 (MD5) Previous issue date: 2017-03-03 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The spin-1=2 and spin-1 Ising models, as well as the spin-1 Blume-Capel model have been studied in one-, two-, and three-dimensional lattices. A variational method based on Bogoliubov inequality for the free-energy has been employed. The trial Hamiltonians consist of clusters of free spins, pairs of spins, and a combination of free spins and pairs of spins. For the three approximations, the thermodynamic quantities of interest have been calculated, together with the critical transition temperature and the behavior close to the transition, in the latter case in order to compute the corresponding critical exponents. The results have been compared to each other as well with exact results, when available, or results coming from more reliable approximate methods. It has been noted that as more interactions are taken into account in the trial Hamiltonian, better results are obtained for the transition temperature, although the critical exponents are always the mean eld like ones. / Os modelos de Ising de spin-1=2 e spin-1, e o de Blume-Capel de spin-1 foram estudados em redes de uma, duas e três dimensões. Foi empregado o método variacional baseado na desigualdade de Bogoliubov para a energia livre. Os hamiltonianos tentativa utilizados consistem em blocos de spins livres, de pares de spins, e da combinacão de spins livres mais pares de spins. Para as três aproximacões, foram obtidas as quantidades termodinâmicas de interesse, bem como a temperatura crítica e o comportamento perto da transição, neste ultimo caso para se obter os respectivos expoentes críticos. Os resultados foram comparados entre si, bem como com os resultados exatos, quando dispon veis, ou provenientes de outras aproxima c~oes mais elaboradas. Veri ca-se que a medida que se incorpora mais intera c~oes nos hamiltonianos tentativa, melhores resultados s~ao obtidos para a temperatura de transi c~ao, embora os expoentes cr ticos continuem sempre sendo os mesmo de campo médio usual. Palavras-Chave: Modelo de Ising,Blume-Capel,desigualdade de Bogoliubov, campo médio.
36

English Learners in Arizona Public Schools: Challenges and Opportunities for Achieving Quality Language Development

January 2012 (has links)
abstract: Arizona's English Language Development Model (ELD Model) is intended to increase and accelerate the learning of English by English Language Learners (ELLs), so that the students can then be ready, when they know the English language, to learn the other academic subjects together with their English speaking peers. This model is part of a response to comply with the Flores Consent Order to improve services for ELLs in Arizona public schools. Whether or not it actually has improved instruction for ELLs has been the subject of much debate and, in 2012, after four years of the requirement to use Arizona's ELD Model, the ELL students who were identified as reclassified for the six districts in the study did not pass the Arizona's Instrument to Measure Standards (AIMS) test. The model's requirement to separate students who are not proficient from students who are proficient, the assessment used for identification of ELLs, and the Structured English Immersion four hours of English only instruction are at the nexus of the controversy, as the courts accepted the separate four hour SEI portion of the model for instruction as sufficient to meet the needs of ELLs in Arizona (Garcia, 2011, Martinez, 2012, Lawton, 2012, Lillie, 2012). This study examines student achievement in Reading and Math as measured by AIMS standards-based tests in six urban K-8 public school districts between 2007-2012. This period was selected to cover two years before and four years after the ELD model was required. Although the numbers of ELLs have decreased for the State and for the six urban elementary districts since the advent of the Arizona ELD Model, the reclassified ELL subgroup in the studied districts did not pass the AIMS for all the years in the study. Based on those results, this study concludes with the following recommendations. First, to study the coming changes in the language assessments and their impact on ELLs' student achievement in broad and comprehensive ways; second, to implement a model change allowing school districts to support their ELLs in their first language; and, finally, to establish programs that will allow ELLs full access to study with their English speaking peers. / Dissertation/Thesis / Ed.D. Educational Administration and Supervision 2012
37

Optimalizace bramového plynulého odlévání oceli za pomoci numerického modelu teplotního pole / Optimization of Slab Concasting Via Numerical Model of Temperature Field

Mauder, Tomáš January 2012 (has links)
The thesis deals with optimization of the continuous slab casting process. The thesis summarizes the basic analytical and empirical findings concerning to the solidification process, the numerical modeling and the selected optimization techniques. Physical conditions and factors that affect the quality of steel including their relationships are also described. The basis of the solution strategy is the original numerical model of the temperature field in its off-line version. The numerical model was verified by the real historical data. The optimization part is based on the fuzzy logic implemented above the numerical model. The optimization algorithm is used for the optimal control of the casting process. The universal usage of the optimization model is demonstrated on several cases, e.g. the finding of optimal casting parameters that ensure the high quality of products, the optimal reactions on breakdown situations, the determination of an optimal relationship between casting parameters, etc. Based on optimization results, the suitable caster modification to increase the surface temperature at the unbending point was proposed. The whole concept of the numerical and optimization model is general and it can be applied to arbitrary slab or billet continuous casting.
38

New Computational Techniques in FJRW Theory with Applications to Landau Ginzburg Mirror Symmetry

Francis, Amanda 14 June 2012 (has links) (PDF)
Mirror symmetry is a phenomenon from physics that has inspired a lot of interesting mathematics. In the Landau-Ginzburg setting, we have two constructions, the A and B models, which are created based on a choice of an affine singularity with a group of symmetries. Both models are vector spaces equipped with multiplication and a pairing (making them Frobenius algebras), and they are also Frobenius manifolds. We give a result relating stabilization of singularities in classical singularity to its counterpart in the Landau-Ginzburg setting. The A model comes from so-called FJRW theory and can be de fined up to a full cohomological field theory. The structure of this model is determined by a generating function which requires the calculation of certain numbers, which we call correlators. In some cases the their values can be computed using known techniques. Often, there is no known method for finding their values. We give new computational methods for computing concave correlators, including a formula for concave genus-zero, four-point correlators and show how to extend these results to find other correlator values. In many cases these new methods give enough information to compute the A model structure up to the level of Frobenius manifold. We give the FJRW Frobenius manifold structure for various choices of singularities and groups.
39

Quantum instability of the Cauchy horizon in Reissner–Nordström–deSitter spacetime

Hollands, Stefan, Wald, Robert M., Zahn, Jochen 27 April 2023 (has links)
In classical general relativity, the values of elds on spacetime are uniquely determined by their values at an initial time within the domain of dependence of this initial data surface. However, it may occur that the spacetime under consideration extends beyond this domain of dependence, and elds, therefore, are not entirely determined by their initial data. This occurs, for example, in the well-known (maximally) extended Reissner–Nordström or Reissner–Nordström–deSitter (RNdS) spacetimes. The boundary of the region determined by the initial data is called the ‘Cauchy horizon.’ It is located inside the black hole in these spacetimes. The strong cosmic censorship conjecture asserts that the Cauchy horizon does not, in fact, exist in practice because the slightest perturbation (of the metric itself or the matter elds) will become singular there in a sufciently catastrophic way that solutions cannot be extended beyond the Cauchy horizon. Thus, if strong cosmic censorship holds, the Cauchy horizon will be converted into a ‘nal singularity,’ and determinism will hold. Recently, however, it has been found that, classically this is not the case in RNdS spacetimes in a certain range of mass, charge, and cosmological constant. In this paper, we consider a quantum scalar eld in RNdS spacetime and show that quantum theory comes to the rescue of strong cosmic censorship. We nd that for any state that is nonsingular (i.e., Hadamard) within the domain of dependence, the expected stress-tensor blows up with afne parameter, V, along a radial null geodesic transverse to the Cauchy horizon as TVV ∼ C/V 2 with C independent of the state and C 6= 0 generically in RNdS spacetimes. This divergence is stronger than in the classical theory and should be sufcient to convert the Cauchy horizon into a singularity through which the spacetime cannot be extended as a (weak) solution of the semiclassical Einstein equation. This behavior is expected to be quite general, although it is possible to have C = 0 in certain special cases, such as the BTZ black hole
40

Building a fire propagation system in real-time graphics / Skapande av brandspridningssystem i realtidsgrafik

Olsson, Kristian January 2017 (has links)
This report covers the creation of a dynamic fire propagation method for a real-time environment. The purpose is to see if it is possible to create a system that can control fire propagation behaviour and visual design based on some sort of simple parametrization, the purpose stems from the lack of a system to control and design a fire propagation scenario. To attain the results, a fire propagation method is devised based on the purpose of having a parameter based system, this method is created through the use of scripting in a real-time game engine to control visuals and behaviour of built in particle systems. Results show fire propagation through an example scenario where the fire behaves differently based on the material that is burning, based on parameters set by an artist. These results conclude that is it possible to create a parameter based fire propagation system and that it can be used to change the visual design and behaviour and be expanded to provide better artist input and control. The report suggests further research in the area of simplified controlled fire simulation in real-time engines, and usability. / Den här rapporten täcker skapandet av en metod för dynamisk eldspridning i en realtidsmiljö. Syftet är att se om det är möjligt att skapa ett system som kan kontrollera spridningsbeteendet och den visuella designen av elden baserat på någon sorts simplifierad parametrisering, Syftet härstammar ifrån att det saknas system där man kan kontrollera och designa ett eldspridningsscenario. För att nå resultat så skapas en metod som är baserad på syftet att använda ett parameterbaserat system, denna metoden skapas med hjälp av programmering i en realtidsmotor genom att kontrollera det visuella samt beteendet hos inbyggda partikelsystem. Resultatet visar eldspridning genom ett exempelscenario där elden beter sig olika baserat på vilket material som brinner, baserat på parametrar som är satta av en artist. Slutsatsen av resultatet visar att det är möjligt att skapa ett parameterbaserat eldspridningssystem och att det kan användas för att kontrollera den visuella designen och beteende samt att det kan expanderas för att förse artister med bättre kontroll över systemet. Rapporten föreslår fortsatta studier inom området simplifierade kontrollerade eldsimulationer inom realtidsmotorer, och användarvänlighet.

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