• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 179
  • 88
  • 68
  • 32
  • 23
  • 16
  • 12
  • 7
  • 4
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 513
  • 131
  • 72
  • 55
  • 53
  • 52
  • 46
  • 44
  • 43
  • 41
  • 40
  • 40
  • 37
  • 35
  • 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

Strain partitioning in transpression zones : examples from the Iapetus Suture Zone in Britain and Ireland

Clegg, Phillip January 2002 (has links)
Kinematic partitioning in transpression zones is well documented and leads to the development of discrete domains of contraction- and wrench-dominated deformation. Although widely reported there are few detailed descriptions of such partitioning in ancient transpression zones. The lapetus Suture Zone comprises a broad band of Lower Palaeozoic rocks that were deformed within a sinistral transpression zone immediately prior to or during the Acadian phase of the Caledonian Orogeny. Excellent coastal exposure of these rocks in SE Ireland, the Isle of Man and SE Scotland allow detailed comparative studies of the deformational patterns and processes within an ancient transpression zone to be made. All three areas preserve a highly heterogeneous assemblage of contemporaneous structures, including folds, interlinked strike-slip detachment faults and a regional cleavage that locally transects in a clockwise sense. Geometrically and kinematically different assemblages of these structures define a series of fault bounded, structural domains that are interpreted to result from the kinematic partitioning of a regional triclinic transpressional deformation. This interpretation lends support to assertions that many transpression zones are triclinic in nature. However, the geometric and kinematic patterns in the different domains suggest a strain model where the triclinic transpressional strain is partitioned into monoclinic end-members (dip-slip non-coaxial contraction and strike-slip simple shear) rather than into domains of pure shear and oblique simple shear. Clockwise transacted cleavage, sinistral strike-slip faulting and zones of sideways and downwards facing sinistrally verging folds have been used to infer sinistral transpressive strain. This project suggests that such features are particularly obvious in regions where significant amounts of partitioning have occurred. The nature and distribution of strain partitioning appears to be controlled by the presence of mechanical heterogeneities on regional and local scales, e.g. the proximity to weak tract-bounding faults and the presence of lithologically controlled regions of high pore fluid pressures, respectively.
2

Über die einförmige Bewegung des ebenen kreisverwandt-veränderlichen Systems

Herrmann, Ernst, January 1913 (has links)
Thesis (doctoral)--Königl. Sächs. Technischen Hochschule zu Dresden, 1913. / Vita.
3

Meetkundige beschouwingen over bewegingen in een Euclidische ruimte

Oosten, Cornelis Petrus Stephanus van. January 1951 (has links)
Thesis--Leyden. / Summary in French and Esperanto. "Stellingen": [2] p. inserted.
4

Automated Kinematic Assembly Modeling

Dawari, Avinash 07 1900 (has links) (PDF)
The aim of this research is to bridge the gap between CAD modeling and kinematic analysis packages by extracting kinematic information directly from part genometries. It will relieve the designers from the tedious task of specifying assembly constraints and specifying redundant information for creating kinematic models. Automatic generation of kinematic assembly models is achieved by characterizing the lower kinematic pairs: cylindrical, spherical, prismatic, planar and revolute; from the geometries point of view. Based on characterization, the algorithms are developed to recognize these kinematic pairs from a pair of part genometries. The combinations of primitive genometric entities: vertices, edges and faces; forming point, line, arc and surface contacts are studied. The signature geometry is found to be associated with each type of joint. The contacts are analysed for restraining the relative motion between a pair of parts. Based on this, the form closure conditions are derived for surface, line, arc and point contacts for each type of joint. The algorithms are developed to automatically recognize these joints and to assemble them into a kinematic assembly model represented as a graph. The strength and novelty of the present procedure is that kinematic pairs can be recognized for conforming as well as non conforming genometries. A Visual Basic for Application (VBA) for Solid Works has been developed using Application Programming Interface (API) for user interaction. The part genometries can be in any 3D solid modeling neutral file format (.sat, .igs, etc) or some of the native formats of CAD softwares supported by Solid Works. The regions of interest can be directly identified through mouse pick on parts using Solid Works Graphical User Interface (GUI). The transformation matrices are derived automatically to position the parts relative to each other. The local interference between part geometries is also considered for checking the validity of the kinematic pair in the assembly. Assembly model is created and represented as a directed graph. The present implementation, built on the ACIS geometry kernel, imports the parts into SolidWorks, specifies the mating regions using a visual Basic interfaces and finally generates the kinematic assembly model as an ADAMS input file complete with part genometries, their mass properties, kinematic joints and their locations.
5

Kinematic control of redundant knuckle booms

Löfgren, Björn January 2004 (has links)
<p>A kinematically redundant four degrees of freedommanipulator arm, a knuckle boom, is studied. Three joints arerevolute and one linear. Since only three degrees of freedomare needed for positioning, we have one redundant degree offreedom. Three different kinematic control strategies arestudied. One is based on the maximization of velocity (localoptimisation). This strategy is non-repeatable and cansometimes lead to kinematically unfavourable positions. In thesecond strategy, which is based on the maximization of staticlifting capacity (local optimisation), one of the degrees offreedom (the linear joint) is made a function of the toolcentre point position. The third strategy, which is based ondynamic programming (global optimization), calculates theshortest time that is possible for the tool centre point to gofrom one point to another point in the working area. The threestrategies are compared in a simulation study. The simulationsshow the necessary speed requirements for all joints whenperforming straight paths in the manipulator work area. Thesimulations also show the difference in time consumptionsbetween the three control algorithms and also what happens whenthe joints reach their maximum velocity limits.</p><p><strong>Keywords</strong>Manipulator, Kinematic Control, RedundantLanguage</p>
6

A longitudinal study into the maturation of gait in chidren

Mann, Alison M. January 2000 (has links)
No description available.
7

A framework in support of structural monitoring by real time kinematic GPS and multisensor data

Ogaja, Clement, Surveying & Spatial Information Systems, Faculty of Engineering, UNSW January 2002 (has links)
Due to structural damages from earthquakes and strong winds, engineers and scientists have focused on performance based design methods and sensors directly measuring relative displacements. Among the monitoring methods being considered include those using Global Positioning System (GPS) technology. However, as the technical feasibility of using GPS for recording relative displacements has been (and is still being) proven, the challenge for users is to determine how to make use of the relative displacements being recorded. This thesis proposes a mathematical framework that supports the use of RTK-GPS and multisensor data for structural monitoring. Its main contributions are as follows: (a) Most of the emerging GPS-based structural monitoring systems consist of GPS receiver arrays (dozens or hundreds deployed on a structure), and the issue of integrity of the GPS data generated must be addressed for such systems. Based on this recognition, a methodology for integrity monitoring using a data redundancy approach has been proposed and tested for a multi-antenna measurement environment. The benefit of this approach is that it verifies the reliability of both the measuring instruments and the processed data contrary to the existing methods that only verifies the reliability of the processed data. (b) For real-time structural monitoring applications, high frequency data ought to be generated. A methodology that can extract, in real-time, deformation parameters from high frequency RTK measurements is proposed. The methodology is tested and shown to be effective for determining the amplitude and frequency of structural dynamics. Thus, it is suitable for the dynamic monitoring of towers, tall buildings and long span suspension bridges. (c) In the overall effort of deformation analysis, large quantities of observations are required, both of causative phenomena (e.g., wind velocity, temperature, pressure), and of response effects (e.g., accelerations, coordinate displacements, tilt, strain, etc.). One of the problems to be circumvented is that of dealing with excess data generated both due to process automation and the large number of instruments employed. This research proposes a methodology based on multivariate statistical process control whose benefit is that excess data generated on-line is reduced, while maintaining a timely response analysis of the GPS data (since they can give direct coordinate results). Based on the above contributions, a demonstrator software system was designed and implemented for the Windows operating system. Tests of the system with datasets from UNSW experiments, the Calgary Tower monitoring experiment in Canada, the Xiamen Bank Building monitoring experiment in China, and the Republic Plaza Building monitoring experiment in Singapore, have shown good results.
8

Folds above angular fault bends: mechanical constraints for backlimb trishear kinematic models

Zhang, Li 15 November 2004 (has links)
The backlimb trishear velocity field is compared to that of mechanical models of fault-bend folds in an incompressible anisotropic viscous media to determine the relationship between the magnitude and orientation of mechanical anisotropy and the kinematic parameters of the trishear model. The trishear model can describe the velocity field of the mechanical model, at least to first order approximation for some cases. We find that the apical angle, asymmetry angle and overall geometry of the hanging-wall syncline above the ramp depend on the magnitude and orientation of the planar anisotropy inherent in stratigraphic sequences. The asymmetry of trishear zone in the backlimb region mimics that of the planar anisotropy. In general, as the magnitude and inclination of the anisotropy increase, the trishear apical angle decreases. The trishear parameters that describe physical models of fault-bend folds with different magnitudes of anisotropy also show a decrease in apical angle with an increase in magnitude of anisotropy. Yet the apical angles of the backlimb of physical models generally are less than these predicted by the mechanical model for the same magnitude of anisotropy. In addition, the physical models display significantly more negative asymmetry than predicted by the mechanical model. The results of this study may be used to determine the conditions under which the trishear model is an acceptable approximation to natural formation and help guide the selection of trishear parameters for subsurface structural interpretations in fault-fold terrains.
9

Folds above angular fault bends: mechanical constraints for backlimb trishear kinematic models

Zhang, Li 15 November 2004 (has links)
The backlimb trishear velocity field is compared to that of mechanical models of fault-bend folds in an incompressible anisotropic viscous media to determine the relationship between the magnitude and orientation of mechanical anisotropy and the kinematic parameters of the trishear model. The trishear model can describe the velocity field of the mechanical model, at least to first order approximation for some cases. We find that the apical angle, asymmetry angle and overall geometry of the hanging-wall syncline above the ramp depend on the magnitude and orientation of the planar anisotropy inherent in stratigraphic sequences. The asymmetry of trishear zone in the backlimb region mimics that of the planar anisotropy. In general, as the magnitude and inclination of the anisotropy increase, the trishear apical angle decreases. The trishear parameters that describe physical models of fault-bend folds with different magnitudes of anisotropy also show a decrease in apical angle with an increase in magnitude of anisotropy. Yet the apical angles of the backlimb of physical models generally are less than these predicted by the mechanical model for the same magnitude of anisotropy. In addition, the physical models display significantly more negative asymmetry than predicted by the mechanical model. The results of this study may be used to determine the conditions under which the trishear model is an acceptable approximation to natural formation and help guide the selection of trishear parameters for subsurface structural interpretations in fault-fold terrains.
10

Automatically coupling elements of dissimilar dimension in finite element analysis

Monaghan, Dermot James January 2000 (has links)
No description available.

Page generated in 0.8847 seconds