• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 440
  • 141
  • 31
  • 29
  • 8
  • 5
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 689
  • 525
  • 516
  • 316
  • 309
  • 151
  • 148
  • 68
  • 66
  • 57
  • 42
  • 39
  • 35
  • 32
  • 32
  • 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.
1

A comparative approach to national protectional law (1940-1956)

Erdemir, Ömer. Supervisor : Akgün, Seçil Karal. January 2005 (has links) (PDF)
Thesis (M.S.) -- Middle East Technical University, 2004. / Keywords: national protectional law, World War II, Republican People's Party, Democratic Party, Etatism.
2

Issues of evidence, interpretation and judgement in Renaissance English drama, c. 1580-1640

Mukherji, Subha January 2000 (has links)
No description available.
3

Topics on the stochastic Burgers’ equation

Hu, Yiming January 1994 (has links)
No description available.
4

The actinorhizal symbiosis of the earliest divergent Frankia cluster

Nguyen, Thi Thanh Van January 2017 (has links)
In recent years, the need to reduce reliance on synthetic nitrogen fertilizer has led to extensive research on biological nitrogen fixation, especially on root nodule symbioses. My study focuses on actinorhizal symbioses, the symbiotic interactions between members of nitrogen-fixing soil actinobacteria from the genus Frankia and a diverse group of plants from eight families, collectively called actinorhizal plants. Frankia cluster II has been shown to be sister to all other clusters. Thus, one of my aims was to gain insight into this cluster to get more information about the evolution of actinorhizal symbioses. The first sequenced genome of a member from this cluster Candidatus Frankia datiscae Dg1 originated from Pakistan. This strain contains the canonical nod genes nodABC responsible for the synthesis of lipochitooligosaccharide Nod factors. In this thesis, we obtained three Frankia inocula from North America (USA), one from Europe (France), one from Asia (Japan) and one from Oceania (Papua New Guinea). Thirteen metagenomes were sequenced based on gDNA isolated from root nodules of Datisca glomerata (Datiscaceae), Ceanothus thyrsiflorus (Rhamnaceae), Coriaria myrtifolia and Coriaria arborea (Coriariaceae). This study shows that members of Frankia cluster II come in teams, helping to explain the ability of cluster II to nodulate a wide host range, four families from two orders. The inoculum from Papua New Guinea, the only sequenced strain from the Southern Hemisphere so far, contains a new Frankia species, which was proposed as Candidatus Frankia meridionalis. All cluster II strains in this study contain the canonical nod genes nodABC, with the exception of the strain from Papua New Guinea which contains only nodB’C. All North American metagenomes also contain the sulfotransferase gene nodH. This gene shows host plant-specific expression in that it was expressed in nodules of C. thyrsiflorus but not in D. glomerata. Phylogenetic analysis and transposase frequencies of the new genomes strongly support the hypothesis that the extension of the cluster II host range from Coriaria to Datisca occurred in Eurasia and that cluster II strains came to North America via the Bering Strait. To acquire more information of the influence of the host plant on the behavior of the microsymbionts, the bacterial metabolism in nodules of D. glomerata (Cucurbitales) and C. thyrsiflorus (Rosales) were compared at the level of transcription. The system to protect nitrogenase from oxygen in Ceanothus nodules seems to be more efficient than in Datisca nodules, whereas the bacterial nitrogen metabolism is likely to be similar in both host plants. The amino acid profile of D. glomerata nodules shows that the nitrogenous solutes are dominated by glutamate and arginine, supporting the suggestion that Frankia in D. glomerata nodules exports an assimilated form of nitrogen, most likely arginine. Thus, our data show that cluster II Frankia strains differ from all other Frankia clusters with regard to the presence of the canonical nod genes and their nitrogen metabolism in symbiosis. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript.</p>
5

Shapes of Spacetimes : Collected tales of black holes

Jakobsson, Emma January 2017 (has links)
In theory, the existence of black holes is predicted by general relativity. In reality, there is a general consensus that they exist in space; in particular at the center of many galaxies. The theory of black holes has been around for decades, but there are still interesting questions calling for attention. This doctoral thesis and its four contributions touches upon some of these questions. One challenging theoretical aspect of black holes lies in their definition, the event horizon. For several reasons, this definition is not satisfactory in many contexts, and alternative horizons based on the concept of trapped surfaces have been suggested to take its place. The question raised in Paper I has to do with the location of such surfaces in a simple model of gravitational collapse, the Oppenheimer-Snyder model. A different scenario of gravitational collapse, that of a null shell of dust collapsing in flat spacetime, is the starting point of the original formulation of the Penrose inequality. By a reformulation, this inequality can be turned into a purely geometric relation in Minkowski space. In Paper IV we formulate and prove a (2+1)-dimensional version in anti-de Sitter space. The Penrose inequality sometimes goes under the name of the "isoperimetric inequality for black holes". In Paper III a different kind of isoperimetric inequality is discussed (with less rigour), namely that of the volume contained in a black hole with a given area. In Paper II, the subject of limits of spacetimes is visualized. Again, (2+1)-dimensional anti-de Sitter space finds its use, as a one parameter family of surfaces, capturing the geometry of charged black hole spacetimes, is embedded in it. Thus different limiting procedures are illustrated. Finally, interesting models can be constructed by cutting and gluing in spacetimes, but in doing so one needs to take care, in order to obtain a physically realistic model. With this background as motivation, a study of Lorentzian cones is given. Taken together, all of these contributions make up a collection of interesting aspects of black hole geometry, or, shapes of spacetimes.
6

Proměny jazyka televizního zpravodajství z let 1985 a 2010 / Language transformation in TV news in 1985 and 2010

Geršáková, Jana January 2011 (has links)
This thesis consists of analysis and mutual comparison of television newscast Události and Televizní noviny. Thesis analyses language modifications and selection of language resources in analogue programmes - with the broadcast difference of 25 years on public television. The work presents lexical, syntactic and phonological analysis. Language usage is also represented by a frequency dictionary, which is used in newscast.
7

Elektrisk styrning av mekaniska vibrationer / Electric control of mechanical vibrations

Nilsson, Carolina January 2019 (has links)
In this report a theoretical study have been made in the research field of Materials physics. The system under consideration is based on a similar system from an article. The system consists of a junction between a normal metal and a topological insulator, where one of the materials vibrates. Between the materials there can arise a tunneling current of electrons. The study is to see if an applied voltage over the system can make the vibrating material to exhibit a non-trivial dynamic. From the result we could conclude that the vibrating material were affected by the tunneling current. For different applied voltages we could see a clear difference in the phase and strength of the current when one of the materials vibrated. By studying the Logarithmic Fourier transformation of the current. It was concluded that the system can exhibit resonance, for lower voltages, and that the resonance frequency are dependent on the applied voltage. The calculations of the vibrating material's displacement were done both analytically and numerically. The computations were done using only arbitrary values of the coefficients. / I den här rapporten har en teoretisk studie genomförts inom forsknings området för materialfysik. Systemet som studien utgått ifrån är baserat på ett liknande system ifrån en artikel. Systemet består av en normal metall och en topologisk isolator som är separerade från varandra, där ett av materialen vibrerar. Mellan materialen kan det uppstå en ström av tunnlande elektroner. Studien går ut på att se om en applicerad spänning över systemet kan få det vibrerande materialet att ge upphov till en dynamik som inte är uppenbar. Från resultatet kan vi konstatera att det vibrerande materialet påverkades av tunnelströmmen. För olika applicerade spänningar kunde vi se en tydlig skillnad i strömmens fas och styrka när ett av materialen vibrerade. Genom att studera den Logaritmiska Fourier transformen  av strömmen. Kan vi dra slutsatsen att systemet kan uppvisa resonans för låga spänningar och att resonans frekvensen är beroende av spänningen. Beräkningarna för det vibrerande materialets avvikelse gjordes både analytiskt och numeriskt. Beräkningarna utfördes endast med godtyckliga värden på koefficienterna.
8

A method for introducing flexibility in rigid multibodies from reduced order elastic models

Syrén, Ludvig January 2019 (has links)
In multibody dynamics simulation of robots and vehicles it is common to model the systems as being composed of mainly rigid bodies with articulation joints. With the trend to more lightweight robots, however, the structural flexibility of the robots link’s needs to be considered for realistic dynamic simulations. The link’s geometries are complex and finite element models (FEM) are required to compute the deformations. However, FEM includes too many degrees of freedom for time-efficient dynamics simulation. A popular method is to generate reduced order models from the FE models, but with much fewer degrees of freedom, for fast and precise simulations. In this thesis a method for introducing reduced order models in rigid multibody systems was developed. The method is to divide a rigid body into two rigid bodies. Their relative movement is described by a six degree of freedom restoration force, determined with a reduced order model from Guyan reduction (static condensation). The method was validated for quasistatic deformation of a homogenous beam, a robot link arm with a more complex geometry and in multibody dynamics simulations. Finally the method was tested in simulation of a complete ABB robot with joint actuators, and any significant differences in the motion of the robot tool centre point due to replacing a rigid link arm by a flexible one was demonstrated.The method show good results for computing deformations of the homogenous beam, of the link arm and in the multibody simulation. The differences observed in simulation of a complete robot was expected and demonstrated the method to be applicable in robotic simulations.
9

Simulations of Safety Aspects for Occpuants in Mine Blast Events

Nordström, Pontus January 2019 (has links)
Underbody mine blasts are events during which massive amounts of energy is transferred to a vehicle and its occupants during a very short time. The occupants are usually protected by both external (armor) and internal (seat suspension/belts etc.) features. Here, we aim at improving the safety of vehicles that experience a real threat of mine blasts. Through simulations using the finite element method, modified seat belts, airbags, and vertical seat damping mechanisms were tested. The designs were evaluated through injury criteria established for a virtual test dummy and distance measurements between the occupant and the hull in the simulation model. Modifications to the seat belt geometry that enable faster and stronger response yielded a greater clearance between the occupant’s head and the ceiling of the vehicle. This came at a cost of higher injury values, mainly in the neck. For a test case where the occupant’s head would hit the ceiling, airbags were shown to be able to prevent the impact and decrease injury values that were previously above the acceptance limit. The effect of a proposed damped seat construction was tested with regards to the stiffness and damping constants of the damping mechanism. It was shown that a damped mechanism can decrease the value of the injury criteria related to the acceleration of the spine by over 50 %. / Vid minsprängningar under fordon överförs stora mängder energi till fordonet under väldigt kort tid. Passagerare skyddas av både yttre (pansar) och inre (stolsupphängning, bälten m.m.) åtgärder. Här försöker vi öka säkerheten i fordon för vilka minor är ett reellt hot. Genom simuleringar som använder finita elementmetoden testades och utvärderades modifierade stolsbälten, luftkuddar, och dämpningsmekanismer genom skadekriterier för en virtuell testdocka och avståndsmätningar mellan passageraren och fordonet i simuleringsmodellen. Modifikationer av bältesgeometrin som ger en snabbare respons i bältet resulterade i ökad fri höjd mellan passagerarens huvud och fordonets innertak. Med detta följde dock högre skadevärden, främst i nacken. För ett testfall där passagerarens huvud slog i taket kunde luftkuddar förhindra kollisionen och minska skadevärden som tidigare låg över gränsen. Beteendet av en föreslagen dämpad säteskonstruktion testades med avseende på fjäder- och dämpningskonstanten av den dämpande mekanismen. En dämpad konstruktion visades kunna minska värdet på ett skadekriterium för ryggradens acceleration med över 50 %.
10

Recombinant expression of Verrucomicrobium spinosum tyrosinase in Escherichia coli, its purification and characterisation

Winroth, Lena January 2019 (has links)
No description available.

Page generated in 0.0346 seconds