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Full-Text Articles in Engineering
A Least-Squares/Galerkin Split Finite Element Method For Incompressible And Compressible Navier-Stokes Equations, Rajeev Kumar
A Least-Squares/Galerkin Split Finite Element Method For Incompressible And Compressible Navier-Stokes Equations, Rajeev Kumar
Mechanical and Aerospace Engineering Dissertations
Over the years Galerkin finite element method along with its variants has been used to solve incompressible and compressible Navier-Stokes equations. The Galerkin method which is more suited for self-adjoint type system of equations like in solid mechanics and heat conduction struggles when applied to non self-adjoint type systems like one encountered in fluid dynamics. Velocity and pressure variables have to be approximated using functions which belong to different spaces and must satisfy the tough LBB condition. The least-squares finite element method (LSFEM), which is based on minimizing the l2-norm of the residual, has many attractive advantages over Galerkin finite …
The Development And Testing Of Pulsed Detonation Engine Ground Demonstrators, Philip Koshy Panicker
The Development And Testing Of Pulsed Detonation Engine Ground Demonstrators, Philip Koshy Panicker
Mechanical and Aerospace Engineering Dissertations
The successful implementation of a PDE running on fuel and air mixtures will require fast-acting fuel-air injection and mixing techniques, detonation initiation techniques such as DDT enhancing devices or a pre-detonator, an effective ignition system that can sustain repeated firing at high rates and a fast and capable, closed-loop control system. The control system requires high-speed transducers for real-time monitoring of the PDE and the detection of the detonation wave speed. It is widely accepted that the detonation properties predicted by C-J detonation relations are fairly accurate in comparison to experimental values. The post-detonation flow properties can also be expressed …
A Mathematical Model Development And Sensitivity Analysis Of Two Photon Polymerization For 3d Micro/Nano Fabrication, Nitin Uppal
A Mathematical Model Development And Sensitivity Analysis Of Two Photon Polymerization For 3d Micro/Nano Fabrication, Nitin Uppal
Mechanical and Aerospace Engineering Dissertations
Two photon polymerization (2PP) is an effective technique for the fabrication of complex polymeric 3-D micro/nano features using ultrashort pulses from a NIR laser source. The photosensitive material absorbs two photons and initiates the chain polymerization reaction. The interaction of laser pulses with photo responsive resin creates a voxel (volumetric pixel) which defines the resolution of 2PP process. In this work, a mathematical model of the polymerization process that considers the effects of molecular diffusion and polymerization kinetics on the formation of voxel. The increase in temperature upon polymerization and their effect on the polymerization kinetics and molecular diffusion is …
Design For Reliability In Microoptelectromechanical Systems (Moems), Abiodun Abiodun Fasoro
Design For Reliability In Microoptelectromechanical Systems (Moems), Abiodun Abiodun Fasoro
Mechanical and Aerospace Engineering Dissertations
Microelectromechanical systems (MEMS) is an enabling technology for miniaturization. MEMS consist of micron sized moving mechanical structures and electronics fabricated on a suitable substrate such as silicon. MEMS has found applications in virtually every aspect of human life, ranging from the automobile to the aerospace, and from the telecommunications to the consumer electronic industries. Technology integration has led to several subsets of MEMS e.g. microoptoelectromechanical systems (MOEMS), radio-frequency MEMS (RF MEMS), etc. Together with these added functionalities, by way of technology integration come additional issues and challenges never before experienced by packaging engineers. MEMS and MOEMS package requirements vary widely …
Closed-Form Development Of A Family Of Higher Order Tetrahedral Elements Through The Fourth Order, Sara Elizabeth Mccaslin
Closed-Form Development Of A Family Of Higher Order Tetrahedral Elements Through The Fourth Order, Sara Elizabeth Mccaslin
Mechanical and Aerospace Engineering Dissertations
This research is concerned with the development and implementation of a family of tetrahedral elements through the fourth order. The straight-sided tetrahedral elements are developed in closed-form. This work investigates the efficiency of closed-form implementation of stiffness matrices and error estimators compared to numerical implementation. An additional objective is the compaction of closed-form source-code files which require as little storage space as possible, a more pronounced requirement at high p-levels. For the straight-sided elements through p-level 4, the stiffness matrix, equivalent nodal load vectors, and error estimators (based on nodal averaging) are developed using closed-form equations obtained through the use …
Semi-Analytical Complex Variable Based Stochastic Finite Element Method, Weiya Jin
Semi-Analytical Complex Variable Based Stochastic Finite Element Method, Weiya Jin
Mechanical and Aerospace Engineering Dissertations
The stochastic finite element method (SFEM) is an approach that allows an analyst to define material, load, and geometry parameters as random variables to represent uncertainty in an engineering problem. The method is then used to estimate the probability of exceeding specified performance thresholds. A necessary ingredient for this analysis is consistent, accurate and efficient algorithms for computing finite element response sensitivities. In this work, the semi-analytical complex variable method (SACVM) is introduced as a method for computing accurate response sensitivities of stochastic models. The SACVM incorporates the complex variable method (CVM) with the semi-analytical method (SAM). It takes advantage …
Characterization And Cooling Capacity Enhancement Of A Porous Ceramic Wick Based Coldplate, Mauricio Adrian Salinas
Characterization And Cooling Capacity Enhancement Of A Porous Ceramic Wick Based Coldplate, Mauricio Adrian Salinas
Mechanical and Aerospace Engineering Dissertations
Current passive cooling methods of aerospace and military, high heat-flux electronics include the use of thermal planes made of exotic metal alloys, which have been designed, at a great expense, to have high thermal conductivity and low density (i.e. light weight). Also, phase change modules composed of a metal matrix saturated with a solid phase change material are being employed for systems requiring a transient cooling scheme such as expendable weapons. This method requires the heat to be transferred from the source location, through the metal matrix (typically a porous aluminum foam), to the available phase change material. Preliminary empirical …