• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 250
  • 51
  • 35
  • 33
  • 20
  • 20
  • 20
  • 20
  • 20
  • 20
  • 16
  • 10
  • 6
  • 5
  • 4
  • Tagged with
  • 539
  • 315
  • 77
  • 69
  • 57
  • 50
  • 46
  • 45
  • 41
  • 39
  • 39
  • 39
  • 31
  • 30
  • 30
  • 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.
81

The nature of plastic deformation during single impact and its relevance to solid particle erosion /

Sundararajan, G., January 1981 (has links)
No description available.
82

A dynamical theory of deformable fluid-saturated porous solids /

Hiremath, Mahantesh S. January 1987 (has links)
No description available.
83

The strain-aging behavior of tantalum and associated problems in the theory of plastic deformation of metals /

Hartley, C. S. January 1965 (has links)
No description available.
84

The deformation behavior of bicrystals of Fe-3% Si /

Hook, Rollin Earl January 1966 (has links)
No description available.
85

The effects of non-isothermal heating during tensile and differential tensile testing of type 310 stainless steel, polycrystalline nickel, and single crystal niobium /

Katz, Allan Paul January 1978 (has links)
No description available.
86

An analysis of the high temperature plastic flow of polycrystalline copper /

Cadien, Kenneth Charles. January 1976 (has links)
No description available.
87

High temperature deformation and flow softening in beta zirconium alloys

Heritier, Bernard January 1976 (has links)
No description available.
88

The viscous catenary

Koulakis, John 04 1900 (has links)
Variational techniques are used to develop a theory for the time evolution of a thin strand of viscous fluid suspended from two points. The shape of the strand is approximated to be a parabola and energy conservation is used to derive a differential equation modeling the change in height over time. Data is collected with a high resolution camera and a strobe light to obtain the position and shape of the strand over multiple intervals of time. Three very different and unexpected types of behaviors are observed depending on the initial thickness and shape of the filament. The approximation fits well with one type of behavior but variations in the thickness of the strand, and consequently in the center of mass, need to be factored in to predict the others.
89

Effects of rolling conditions on texture and microstructure development in [alpha] brass

Chen, Yongjin., 陳永進. January 2000 (has links)
published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy
90

Lyapunov-based adaptive methods to servo-control elastic deformations.

January 2014 (has links)
The deformation control problem arises in applications where a mechanical system needs to actively modify the shape of a soft object. This problem is needed in surgical robotics to automate delicate procedures with soft tissues, e.g. suturing and needle insertion, in food industry to automate the shaping of food materials such as dough, or in textile industry to automate the folding and positioning of extensible fabrics, to name a few cases. However, despite the recent progress in physically interactive and soft robotics, the active deformation of compliant objects remains an open research problem with many economically important applications. One of the main issues that complicates the implementation of these types of tasks is the difficulty to identify the deformation properties of soft materials. / The aim of this thesis is to provide model-free solutions to this challenging control design problem. For that, new adaptive methods to servo-control unknown elastic deformations are presented. First, this thesis proposes a kinematic controller that estimates the deformation Jacobian matrix in real-time, hence, avoids the identification of the object’s deformation model. This method computes the unknown matrix based on measurements of the deformation flow and the velocity input to the manipulator; the matrix is then used to map the deformation control action into end-effector velocities. Next, this thesis presents a conceptually different adaptive control approach that does not require to numerically estimate the deformation Jacobian matrix or to numerically compute the optical flow. However, to compute the velocity control input, offline testing deformations must be performed. In this method, the deformation control action is mapped to end-effector velocities by an adaptively varying transposed matrix, thus no matrix inversion is required. / This thesis also tackles the simultaneous vision-based control of multiple elastic deformations. This method incorporates the attitude of a fully-constrained gripper and the measurements from multiple vision sensors into the Jacobian estimation algorithm; by doing this, the number of controllable deformation degrees-of-freedom is increased. Additionally, this thesis addresses the vision-based deformation problem but with torque-controlled manipulators. The presented adaptive method exploits the passivity properties of the system and computes the controller with the online estimated Jacobian matrix. Finally, this thesis formulates the deformation control problem but in terms of force sensory feedback, in other words, the control objective is the regulation of the applied force onto the elastic object; the presented energy shaping controller preserves in closed-loop the Hamiltonian structure of the dynamical system. / The originality of this work lies in the uncalibrated nature of the control methods, i.e. none of the proposed controllers require the identification of the object’s deformation/stiffness model and the camera’s parameters. This uncalibrated feature allows to control on-the-fly elastic deformations of unknown compliant objects. It must be remarked that for each of the control methods, its stability is analysed with Lyapunov theory, and its performance is experimentally verified with robot manipulators. / Navarro Alarcon, David. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 123-132).

Page generated in 0.0994 seconds