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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.
11

A series resonant crystal controlled oscillator

Widerquist, Vernon Roberts 05 1900 (has links)
No description available.
12

Lattice formation in two-dimensional dispersions.

Shah, Pravinchandra Narharilal. January 1967 (has links)
No description available.
13

Structure-property relationships in non-conventional liquid crystalline materials

Cook, Andrew G. January 2001 (has links)
The aim of this thesis is to investigate structure-property relationships in several types of non-conventional liquid crystalline materials. First, supramolecular hydrogen bonded complexes involving either acid or phenol-based donors with pyridyl-based acceptors were studied using FT-IRM. These studies were made to investigate the nature and temperature dependence of the hydrogen bond between the donor and acceptor moieties. Second, a study of carbohydrate liquid crystals was undertaken. In this investigation two different types of carbohydrate-based materials were synthesised; (a) a homologous series of mono-tailed carbohydrates, the methyl-6-O-(<i>n-</i>acyl)-a-D-glucopyranosides were prepared to study the effect of alkyl chain length on phase behaviour and to elucidate how stereochemistry and the position of the alkyl chain affects liquid crystallinity; (b) a novel non-symmetric dimer containing a methoxyazobenzene moiety and a carbohydrate headgroup to study the behaviour of a dimer consisting of two incompatible mesogenic groups. Third, the effect of terminal alkyl chain branching on the molecular organisation in the intercalated smectic. A phase, was studied with a view to exploring the nature of the driving force for smectic phase formation in symmetric and non-symmetric liquid crystal dimers. The symmetric dimer chosen was 4.060.4, while the non-symmetric dimer was CB.060.4. In both systems the <i>n</i>-butyl terminal chains were replaced by either <i>sec-</i>butyl or <i>tert</i>-butyl chains. To establish how these structural changes effect smectic phase formation, binary phase diagrams of <i>n</i>-butyl-based compound with the corresponding branched material have been constructed. Finally, a comparison of the mesogenic properties of a series of monomers, dimers and side-chain liquid crystal polymers containing a methoxyazobenzene mesogenic unit was made. There data were used to examine the virtual trimer model as a means of rationalising the mesogenic behaviour of the polymers.
14

High yield growth of tellurium single crystals by the Czochralski method

Shih, Ishiang January 1977 (has links)
No description available.
15

An investigation into the phase noise of quartz crystal oscillators /

Bentley, Brendon January 2007 (has links)
Thesis (MScIng)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.
16

Glycoside Hydrolases, Family GH73 and a Structural Characterization of GH73 Enzyme FlgJ

Zaloba, Patryk 14 January 2016 (has links)
FlgJ belongs to Carbohydrate Active enZyme (CAZy) family GH73 and facilitates passage of the bacterial flagellum through the peptidoglycan (PG) layer by cleaving the glycosidic bonds within glycan strands of PG. In this thesis I present the structure of the GH73 enzyme FlgJ from bacterial pathogenSalmonella typhimurium (St FlgJ). The St FlgJ active site was found to be blocked by the C-terminus of a neighbouring symmetry mate. To investigate if the C-terminus of FlgJ inhibits enzymatic activity similarly to the N-terminus of GH73 enzyme Auto, the glycolytic activity of St FlgJ was measured with and without its C-terminus. The assays revealed St FlgJ activity to be unaffected by the presence of the C-terminal sequence. Removal of the C-terminus did, however, allow a crystal structure of the domain to be obtained where a β-hairpin known to accommodate critical catalytic residues was found capable of opening widely, which likely aids in substrate capture and turnover. / February 2016
17

Lattice formation in two-dimensional dispersions.

Shah, Pravinchandra Narharilal. January 1967 (has links)
No description available.
18

High yield growth of tellurium single crystals by the Czochralski method

Shih, Ishiang January 1977 (has links)
No description available.
19

NUMERICAL STUDY OF DEFORMATION MECHANISMS IN HCP METALS

QIAO, HUA January 2016 (has links)
The operative deformation mechanisms which include both dislocation slip and twinning have a significant impact on the mechanical response of hexagonal close-packed (HCP) metals. Twinning plays an important role in accommodating plastic deformation due to the limited number of independent slip systems in HCP metals. The objective of this research is to study the deformation mechanisms associated with twinning in HCP metals (magnesium and zirconium alloys). Heat treatments are often involved in the manufacturing of zirconium alloys. These alloys exhibit a strong thermal anisotropy with a thermal expansion coefficient along the c-axis nearly two times of that along a-direction. Therefore, residual stresses/strains are generated during the heat treatment process which influences the mechanical response (e.g. lattice evolution) under subsequent loading. The elastic viscoplastic self-consistent (EVPSC) model has been improved which includes thermal strain to study the behavior of a Zircaloy-2 slab under moderately large strains. Various self-consistent schemes (SCSs) of the EVPSC model are evaluated in terms of the deformation behavior of the material under different uniaxial strain paths. Numerical results show that the Affine and Meff=0.1 self-consistent models give much better performance for the Zircaloy-2 slab than the Secant and Tangent models. The EVPSC-TDT model has been employed to mimic the twinning and detwinning behavior of extruded Mg alloy ZK60A under monotonic and cyclic loading. The model differentiates between the stress required to initiate twinning and that required to grow (thicken) existing twins. This enables the model to simulate the unusual sharp yielding behavior during twinning as well as the gradual yielding associated with detwinning. It is demonstrated that this model gives a good prediction of the strength anisotropy, strength asymmetry, and strain hardening behavior along different directions, for cases in which the contribution of twinning is large, small and intermediate. For the first time, the lattice strain evolution is well predicted in an extruded magnesium alloy under cyclic loading which involves twinning and detwinning. In all polycrystal models, an empirical equation for the termination of twinning in a grain is required. A new physics-based empirical equation for describing this phenomenon in magnesium alloys has been proposed in this study. It should be noted that the popular empirical equation currently used in all polycrystal models is applied at the grain level, while the new empirical equation is introduced at the twinning system level. The new description is represented by a single parameter while the commonly used empirical equation depends on two parameters. It is demonstrated that the proposed empirical equation is easily calibrated with the single parameter and is able to accurately simulate the experimentally observed rapid hardening associated with twinning exhaustion. / Thesis / Doctor of Philosophy (PhD)
20

Modelling of dislocations in silicon

Valladares, Alexander January 1999 (has links)
No description available.

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