Search results for "Numerical Analysis"
showing 10 items of 883 documents
A Smoothed Particle Interpolation Scheme for Transient Electromagnetic Simulation
2006
In this paper, the fundamentals of a mesh-free particle numerical method for electromagnetic transient simulation are presented. The smoothed particle interpolation methodology is used by considering the particles as interpolation points in which the electromagnetic field components are computed. The particles can be arbitrarily placed in the problem domain: No regular grid, nor connectivity laws among the particles, have to be initially stated. Thus, the particles can be thickened only in distinct confined areas, where the electromagnetic field rapidly varies or in those regions in which objects of complex shape have to be simulated. Maxwell’s equations with the assigned boundary and initi…
Monotonically convergent optimal control theory of quantum systems under a nonlinear interaction with the control field
2008
We consider the optimal control of quantum systems interacting non-linearly with an electromagnetic field. We propose new monotonically convergent algorithms to solve the optimal equations. The monotonic behavior of the algorithm is ensured by a non-standard choice of the cost which is not quadratic in the field. These algorithms can be constructed for pure and mixed-state quantum systems. The efficiency of the method is shown numerically on molecular orientation with a non-linearity of order 3 in the field. Discretizing the amplitude and the phase of the Fourier transform of the optimal field, we show that the optimal solution can be well-approximated by pulses that could be implemented ex…
Corrective meshless particle formulations for time domain Maxwell's equations
2007
AbstractIn this paper a meshless approximation of electromagnetic (EM) field functions and relative differential operators based on particle formulation is proposed. The idea is to obtain numerical solutions for EM problems by passing up the mesh generation usually required to compute derivatives, and by employing a set of particles arbitrarily placed in the problem domain. The meshless Smoothed Particle Hydrodynamics method has been reformulated for solving the time domain Maxwell's curl equations. The consistency of the discretized model is investigated and improvements in the approximation are obtained by modifying the numerical process. Corrective algorithms preserving meshless consiste…
Least energy solutions to the Dirichlet problem for the equation −D(u) = f (x, u)
2017
Let be a bounded smooth domain in RN. We prove a general existence result of least energy solutions and least energy nodal ones for the problem −u = f(x, u) in u = 0 on ∂ (P) where f is a Carathéodory function. Our result includes some previous results related to special cases of f . Finally, we propose some open questions concerning the global minima of the restriction on the Nehari manifold of the energy functional associated with (P) when the nonlinearity is of the type f(x, u) = λ|u| s−2u − μ|u| r−2u, with s, r ∈ (1, 2) and λ,μ > 0.
TRANSIENT SEMICONDUCTOR DEVICE SIMULATION INCLUDING ENERGY BALANCE EQUATION
1992
An efficient numerical method for the solution of hot‐carrier transport equations describing transient processes in submicrometer semiconductor devices is proposed. The calculations of transient processes in submicrometer MOS transistor were carried out and compared with the results obtained by conventional drift‐diffusion model.
Numerical analysis of a new cross-flow type hydraulic turbine for high head and low flow rate
2021
Cross-flow turbines have recently been proposed for energy recovery in aqueducts when the outlet pressure is greater than zero, owing to their constructive simplicity and good efficiency within a large range of flow rates and head drops. In the case of high head drop (higher than 150 m) and relatively small discharge (lower than 0.2 m3/s), the traditional design of these turbines leads to very small widths of the nozzle and the runner; as a consequence, friction losses grow dramatically and efficiency drops down to very low values. Standard Pelton turbines require zero outlet pressure and cannot be used as alternatives. A new counter-pressure hydraulic turbine for high head and low flow rat…
Modelling Aspects in Accumulative Roll Bonding Process by Explicit Finite Element Analysis
2013
Accumulative Roll-Bonding (ARB) process is a severe plastic deformation (SPD) process, capable of developing grains below 1 μm in diameter and improving mechanical properties of the material. In this study, the authors compared two different FE-codes with respect of its applicability for numerical analysis of the ARB process. Modelling this process was achieved using the explicit code for Abaqus/CAE both in 2D and 3D. The proposed model was used to assess the impact of ARB cycles on the final material properties. The numerical results in 2D and 3D were compared and contrasted. The research work presented in this paper is focused on the simulation optimization based on CPU time minimization.…
Cutting Temperatures Evaluation in Ceramic Tools: Experimental Tests, Numerical Analysis and SEM Observations
1994
The authors propose a multiple approach for the evaluation of cutting temperatures in ceramic tools. The first approach was the experimental evaluation of equitemperature lines, obtained in three-dimensional cutting by employing constant melting point powders scattered on planes parallel to rake face. In the second approach, a numerical finite element analysis was performed. At this step the determination of the percentage of total heat produced in the operation that flows into the tool was considered and, consequently, the temperature distribution within the whole volume of the insert. Finally, the examination of the crater zone with SEM microscopy confirmed the temperature levels as previ…
Determination of Nonuniform Residual Stresses Using the Ring-Core Method
1996
This paper considers residual stress analysis using the ring-core method. In particular, the so-called integral equation method is applied to evaluate nonuniform residual stress fields. The proposed method overcomes typical drawbacks of the incremental strain method which lead to incorrect results for strongly varying stress fields. The experimental results obtained with a specimen subjected to a bending load confirm the theoretical predictions.
Improving Formability in SPIF Processes through High Speed Rotating Tool: Experimental and Numerical Analysis
2013
Single-point incremental forming (SPIF) is a quite new sheet-forming process which offers the possibility to deform complex parts without dedicated dies using a single-point tool and a standard three-axis CNC machine. Although the process mechanics enables higher strains with respect to traditional sheet-forming processes, research has been focused on further increasing the maximum forming angle. In the paper, a new approach is used to enhance the material formability through a localized sheet heating as a consequence of the friction work caused by high speed rotating tool. Numerical simulation was utilized to relate the effect of temperature with the main field variables distribution in th…