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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

Modeling Land-use Changes in the South Nation Watershed Using Dyna-CLUE

El Khoury, Antoun 15 June 2012 (has links)
The South Nation watershed is located in Eastern Ontario, Canada and managed under the authority of the South Nation Conservation (SNC). The watershed covers an area of 400,000 hectares with four dominant categories of land-use classes (60% agriculture, 34% forest, 5% mixed urban, and 1% other). Water quality is a great concern for the SNC as many anthropogenic activities generate harmful pollutants (such as heavy metals, nitrogen, phosphorus, and pesticides) that are discharged to the river through surface and groundwater flow. The discharge patterns of these pollutants are mainly driven by land-use distribution within the watershed which has been constantly evolving with urbanization and intensification of agriculture. Major changes in land-uses can potentially offset current SNC efforts to mitigate water pollution. The objective of the current study is to predict land-use series of maps for the South Nation watershed starting from 1991 to 2020. The prediction is carried out using the land-use allocation algorithm of the Dyna-CLUE (Dynamic Conversion of Land-Use and its Effects) model which is implemented for local regions. Dyna-CLUE is a spatially explicit hybrid land-use allocation model that combines estimation and simulation models, and its allocation procedures predict future trends of land-use surface (estimated from historical trends). The binary logistic regression is used to link preferences of land-use classes and potential demographic and geographic driving factors. Expert judgment was used to select a set of spatial driving factors believed to be responsible for changes in land-use distribution in the South Nation watershed. Three different scenarios for future development of the region were considered, with different initial conditions and conversion restrictions. The simulation results were evaluated using visual and statistical validation techniques to assess the performance of the model in generating maps similar to reality. The Dyna-CLUE model was successfully applied to the South Nation watershed. It was observed that the simulated maps generated from the model were in good agreement with the reality maps. This was confirmed through statistical validation via map pair analysis (error matrix) used to assess the overall accuracy of the model predictions. Results showed that the model was sensitive to land-use restrictions. Such type of modeling can be valuable for assessing the land-use changes at the local level, and setting up a decision support system for the South Nation Conservation towards sustainable land-use management in the watershed. Better results are expected to be achieved with more reliable datasets (i.e., accurate classification of land-use types in reality maps). Data availability and quality were the main obstacles that faced this research work. Our work has the merit to be the first application of CLUE model in Eastern Ontario.
12

Developing an efficient FEM structural simulation of a fan blade off test in a turbofan jet engine

Husband, Jason Burkley 29 October 2007
This work develops a methodology for full engine FEA simulation of the fan blade off containment test for a jet engine using LS-Dyna. The fan blade off containment test is a safety requirement involving the intentional release of a fan blade when the engine is running at full power. The released blade must not pierce or fracture the engine cases during the impact or rotating unbalance. The novel feature of the LS-Dyna simulation is the extensive full engine geometry as well as the widespread use of nonlinearities (mainly plasticity and friction) to absorb the large kinetic energies of the engine rotors. The methodology is simple to use, runs quickly and is being recognized by industry as a contender for widespread implementation. Future applications look promising enough that the methodology warrants further development and refinement.
13

Study on performance of curved guard fences using numerical simulation

Hirai, Takashi, 伊藤, 義人, Itoh, Yoshito 12 1900 (has links)
No description available.
14

Constitutive modelling of the nickel base superalloy IN718; a preparatory study

Gustafsson, David January 2008 (has links)
One of the limiting factors in gas turbine design is the allowable metal temperatures and loads in critical components. Specially designed superalloys are used when the conditions are most severe. One of these superalloys is Inconel 718. To be able to design components for higher temperature and higher loads, an accurate understanding and computational model of the material is needed. In this thesis the deformation mechanisms of Inconel 718 have been investigated and a theoretical basis for modelling in a large deformation context has been established. Finally a viscoplastic nonlinear kinematic hardening material model with an Armstrong-Frederick backstress evolution law has been implemented as a first step in describing the constitutive behaviour of the material Inconel 718.
15

Constitutive modelling of the nickel base superalloy IN718, a preparatory study

Gustafsson, David January 2008 (has links)
One of the limiting factors in gas turbine design is the allowable metal temperatures and loads in critical components. Specially designed superalloys are used when the conditions are most severe. One of these superalloys is Inconel 718. To be able to design components for higher temperature and higher loads, an accurate understanding and computational model of the material is needed. In this thesis the deformation mechanisms of Inconel 718 have been investigated and a theoretical basis for modelling in a large deformation context has been established. Finally a viscoplastic nonlinear kinematic hardening material model with an Armstrong-Frederick backstress evolution law has been implemented as a first step in describing the constitutive behaviour of the material Inconel 718.
16

Developing an efficient FEM structural simulation of a fan blade off test in a turbofan jet engine

Husband, Jason Burkley 29 October 2007 (has links)
This work develops a methodology for full engine FEA simulation of the fan blade off containment test for a jet engine using LS-Dyna. The fan blade off containment test is a safety requirement involving the intentional release of a fan blade when the engine is running at full power. The released blade must not pierce or fracture the engine cases during the impact or rotating unbalance. The novel feature of the LS-Dyna simulation is the extensive full engine geometry as well as the widespread use of nonlinearities (mainly plasticity and friction) to absorb the large kinetic energies of the engine rotors. The methodology is simple to use, runs quickly and is being recognized by industry as a contender for widespread implementation. Future applications look promising enough that the methodology warrants further development and refinement.
17

Tensile and Fatigue Responses of Ti/APC-2 Nanocomposite Laminates after Low-Velocity Impact

Chen, Jin-Guan 29 June 2012 (has links)
The aim of this thesis is to investigate Ti/APC-2 nanocomposite laminates mechanical properties after low velocity impact. The finite element analysis with software ANSYS/LS-DYNA is used to analyze the size of damage and plastic zone and internal energy of laminates during low velocity impact. Finally, the numerical results and experimental data are in good agreement. The work can be divided into two parts: the first is to fabricate the hybrid composite laminates and place the samples on the floor, subjected to the free drop of a rigid steel ball of 1m and 2m high. Then, the samples after impact were due to static tensile and fatigue tests to obtain mechanical properties. Using the optical microscopy the impact defects of laminate surface were measured. The second, ANSYS/LS-DYNA was used to simulate a laminate impacted by a steel ball. The energy change of steel ball impact and internal energy of laminates during impact were also discussed. From the experimental data, the mechanical properties, such as ultimate strength and stiffness, of virgin samples are better than those of impacted samples due to free drop. In addition, no matter the laminates were added nanoparticles SiO2 or not, the strength of laminates reduces after impact, however, the fatigue resistance of impacted samples does not lose much. Compare with the data of penetration depth and plastic zone due to free drop. The errors of numerical results are 5.4%~12.4% for the penetration depth and the errors 5.21%~8.98% for plastic zone respectively. That is acceptable. The numerical method ology provides a reference to realize the energy change in laminates after impact. Also, from the experimental measurement it is obvious to see damage area after impact and the mechanical properties do not reduce significantly due to low velocity impact generally in Ti/APC-2 composite laminates.
18

Constitutive modelling of the nickel base superalloy IN718, a preparatory study

Gustafsson, David January 2008 (has links)
<p>One of the limiting factors in gas turbine design is the allowable metal temperatures and loads in critical components. Specially designed superalloys are used when the conditions are most severe. One of these superalloys is Inconel 718. To be able to design components for higher temperature and higher loads, an accurate understanding and computational model of the material is needed. In this thesis the deformation mechanisms of Inconel 718 have been investigated and a theoretical basis for modelling in a large deformation context has been established. Finally a viscoplastic nonlinear kinematic hardening material model with an Armstrong-Frederick backstress evolution law has been implemented as a first step in describing the constitutive behaviour of the material Inconel 718.</p>
19

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)
20

COLLISIION PERFORMANCE OF NEW BRIDGE GUARD FENCES USING THE NUMERICAL SIMULATION

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

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