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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.
171

A Hierarchical Hexagon Data Structure for Collision Detection

Kang, Ting-wei 28 July 2001 (has links)
In this paper, hexagonal grid is extended to hierarchical structure. This technique can be applied to collision detection. By using concept of node, we develop an effectually linear decode called ¡§HCD¡¨. To develop to three dimensions, the structure of octahedron is applied to develop hexagonal hierarchical structure in three dimensions. This is helpful to simulate objects and approximate objects. The object¡¦s data is commonly deposited in float. In this paper, Symmetrical Hexagonal Frame makes whole object to be deposited in integer. So the data of object can be compressed to smaller size. Otherwise, by concept of k-dops, we can close to object¡¦s real surfaces with hierarchical hexagonal structures at low level.
172

Using PIC Method to Predict Transport Variables in Plasma Near an Electrically Biased Surface

Huang, Chih-tsai 09 August 2009 (has links)
This study uses the PIC (Particle-in-cell) method to simulate unsteady three-dimensional transport variables in argon plasma under low pressure and weak ionization between two planar electrodes suddenly biased by a negative voltage. Plasma has been widely used in etching, ion implantation, light source, and encountered in nuclear fusion, etc. Studying transport processes of plasmas therefore is important. This work ignores magnetic field, secondary electron emission, recombination between ions and electrons, and assumes a uniform distribution of the neutrals having velocity of a Maxwellian distribution. Accounting for elastic collisions between electrons and neutrals, ions and neutrals, and inelastic collisions resulting in ionization from impacting neutrals by electrons, and charge exchange between ions and neutrals, the computed results in this work quantitatively show non-isotropic pressures, shear stresses and heat conduction of the ions across the sheath to the surfaces suddenly biased by a dc negative voltage.
173

Étude de systèmes de type gaz-particules

Mathiaud, Julien 13 September 2006 (has links) (PDF)
Cette thèse porte sur l'étude de systèmes de type gaz particules, tant d'un point de vue mathématique que physique et numérique. Par ailleurs, quelques aspects de la turbulence en lien avec ces systèmes et le modèle k- sont étudiés.
174

A study of the requirements for a heads-up display for use in motor transportation in the United States Marine Corps

Moseley, Harold M. Lewis, Rodney L. January 1900 (has links)
Thesis (M.A.)--Naval Postgraduate School, Monterey, Calif., 2001. / "September 2001." Includes bibliographical references (p. 87-90). Available also online as a PDF file via the World Wide Web.
175

Computation of Collision-Induced Absorption by Simple Molecular Complexes, for Astrophysical Applications

Abel, Martin Andreas 17 July 2012 (has links)
The absorption due to pairs of H₂ molecules is an important opacity source in the atmospheres of various types of planets and cool stars, such as late stars, low mass main sequence stars, brown dwarf stars, cool white dwarf stars, the ambers of the smaller, burnt out main sequence stars, exoplanets, etc., and therefore of special astronomical interest. Astronomers are interested in the outer planets as they still contain primordal matter. Furthermore, recent observations by the Hubble space telescope (in operation since 1990) have revealed several thousand cool white dwarf stars with temperatures of several thousand Kelvin. It is surprising that none of them has temperatures lower than roughly 4000 K. This means that the white dwarf stars have not had enough time to cool down to the temperature of the cosmic background radiation. Astrophysicists believe that this information can be used for an alternative and more accurate method of cosmochronology. However, the emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra of their cores, largely due to collision-induced absorption by collisional complexes of residual hydrogen and helium in the stellar atmospheres. In order to model the radiative processes in these atmospheres, which have temperatures of several thousand kelvin, one needs accurate knowledge of the induced dipole and potential energy surfaces of the absorbing collisional complexes, such as H₂--H₂, H₂--He, and H₂--H. These come from quantum-chemical calculations, which, for the high temperatures and high photon energies under consideration in this work, need to take into account that the H₂ bonds can be stretched or compressed far from equilibrium length. Since no laboratory measurements for these high temperatures and photon energies exist, one has to undertake \textit{ab initio} calculations which take into account the high vibrational and rotational excitation of the involved hydrogen molecules. However, before one attempts to proceed to higher temperatures and photon energies where no laboratory measurements exist it is good to check that the formalism is correct and reproduces the results at temperatures and photon energies where laboratory measurements exist, that is, at and below room temperature and for photon energies up to about 1.5 eV. In this work a formalism is developed to compute the binary collision-induced absorption of simple molecular complexes up to temperatures of thousands of kelvin and photon energies up to 2.5 eV, properly taking into account vibrational and rotational dependencies of the induced dipole and potential energy surfaces. In order to make the computational effort feasible, the isotropic potenial approximation is employed. The formalism is applied to collisional complexes of H₂--H₂, D₂--D₂, H₂--He, D₂--He, T₂--He, and H₂--H, and compared with existing laboratory measurements. / text
176

Performances of Curved Steel Bridge Railing Using the Numerical Analysis

Itoh, Yoshito, Le, Thanh 09 1900 (has links)
9th German-Japanese Bridge Symposium, September 10-11, 2012, Kyoto, JAPAN (GJBS09)
177

A STUDY ON THE PERFORMANCE OF HYBRID GUARD FENCES SUBJECTED TO VEHICLE COLLISION

Liu, C, Hattori, R, Itoh, Y 12 1900 (has links)
No description available.
178

COMPUTER SIMULATION OF ON-SITE FULL-SCALE TESTS OF SINGLE-SLOPE CONCRETE GUARD FENCES

Kusama, R., Liu, C., Itoh, Y. 12 1900 (has links)
No description available.
179

COLLISIION PERFORMANCE OF NEW BRIDGE GUARD FENCES USING THE NUMERICAL SIMULATION

Takadoh, Osamu, Itoh, Yoshito, Itoh, Seiji 11 1900 (has links)
No description available.
180

The Structural and Geomorphic Development of Active Collisional Orogens, from Single Earthquake to Million Year Timescales, Timor Leste and New Zealand

Duffy, Brendan Gilbert January 2012 (has links)
The structure and geomorphology of active orogens evolves on time scales ranging from a single earthquake to millions of years of tectonic deformation. Analysis of crustal deformation using new and established remote sensing techniques, and integration of these data with field mapping, geochronology and the sedimentary record, create new opportunities to understand orogenic evolution over these timescales. Timor Leste (East Timor) lies on the northern collisional boundary between continental crust from the Australian Plate and the Banda volcanic arc. GPS studies have indicated that the island of Timor is actively shortening. Field mapping and fault kinematic analysis of an emergent Pliocene marine sequence identifies gentle folding, overprinted by a predominance of NW-SE oriented dextral-normal faults and NE-SW oriented sinistral-normal faults that collectively bound large (5-20km2) bedrock massifs throughout the island. These fault systems intersect at non-Andersonian conjugate angles of approximately 120° and accommodate an estimated 20 km of orogen-parallel extension. Folding of Pliocene rocks in Timor may represent an early episode of contraction but the overall pattern of deformation is one of lateral crustal extrusion sub-parallel to the Banda Arc. Stratigraphic relationships suggest that extrusion began prior to 5.5 Ma, during and after initial uplift of the orogen. Sedimentological, geochemical and Nd isotope data indicate that the island of Timor was emergent and shedding terrigenous sediment into carbonate basins prior to 4.5 Ma. Synorogenic tectonic and sedimentary phases initiated almost synchronously across much of Timor Leste and <2 Myr before similar events in West Timor. An increase in plate coupling along this obliquely converging boundary, due to subduction of an outlying continental plateau at the Banda Trench, is proposed as a mechanism for uplift that accounts for orogen-parallel extension and early uplift of Timor Leste. Rapid bathymetric changes around Timor are likely to have played an important role in evolution of the Indonesian Seaway. The 2010 Mw 7.1 Darfield (Canterbury) earthquake in New Zealand was complex, involving multiple faults with strike-slip, reverse and normal displacements. Multi-temporal cadastral surveying and airborne light detection and ranging (LiDAR) surveys allowed surface deformation at the junction of three faults to be analyzed in this study in unprecedented detail. A nested, localized restraining stepover with contractional bulging was identified in an area with the overall fault structure of a releasing bend, highlighting the surface complexities that may develop in fault interaction zones during a single earthquake sequence. The earthquake also caused river avulsion and flooding in this area. Geomorphic investigations of these rivers prior to the earthquake identify plausible precursory patterns, including channel migration and narrowing. Comparison of the pre and post-earthquake geomorphology of the fault rupture also suggests that a subtle scarp or groove was present along much of the trace prior to the Darfield earthquake. Hydrogeology and well logs support a hypothesis of extended slip history and suggests that that the Selwyn River fan may be infilling a graben that has accumulated late Quaternary vertical slip of <30 m. Investigating fault behavior, geomorphic and sedimentary responses over a multitude of time-scales and at different study sites provides insights into fault interactions and orogenesis during single earthquakes and over millions of years of plate boundary deformation.

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