Search results for "equation"
showing 10 items of 4219 documents
Shape Sensitivity Analysis and Gradient-Based Optimization of Large Structures Using MLFMA
2014
A fast method for computing the action of shape-differentiated electric field integral equation (EFIE) system matrix to a vector is derived exploiting the multilevel fast multipole algorithm (MLFMA). The proposed method is used in conjunction with the adjoint-variable method (AVM) to compute the shape gradient of arbitrary objective functions depending on shape of a metallic scatterer. The method is demonstrated numerically by optimizing the shape of a parabolic reflector illuminated with a half-wave dipole.
On shape differentiation of discretized electric field integral equation
2013
Abstract This work presents shape derivatives of the system matrix representing electric field integral equation discretized with Raviart–Thomas basis functions. The arising integrals are easy to compute with similar methods as the entries of the original system matrix. The results are compared to derivatives computed with automatic differentiation technique and finite differences, and are found to be in an excellent agreement. Furthermore, the derived formulas are employed to analyze shape sensitivity of the input impedance of a planar inverted F-antenna, and the results are compared to those obtained using a finite difference approximation.
A posteriori error estimates for time-dependent reaction-diffusion problems based on the Payne-Weinberger inequality
2015
We consider evolutionary reaction-diffusion problem with mixed Dirichlet--Robin boundary conditions. For this class of problems, we derive two-sided estimates of the distance between any function in the admissible energy space and exact solution of the problem. The estimates (majorants and minorants) are explicitly computable and do not contain unknown functions or constants. Moreover, it is proved that the estimates are equivalent to the energy norm of the deviation from the exact solution.
Reduced Order Models for Pricing European and American Options under Stochastic Volatility and Jump-Diffusion Models
2017
Abstract European options can be priced by solving parabolic partial(-integro) differential equations under stochastic volatility and jump-diffusion models like the Heston, Merton, and Bates models. American option prices can be obtained by solving linear complementary problems (LCPs) with the same operators. A finite difference discretization leads to a so-called full order model (FOM). Reduced order models (ROMs) are derived employing proper orthogonal decomposition (POD). The early exercise constraint of American options is enforced by a penalty on subset of grid points. The presented numerical experiments demonstrate that pricing with ROMs can be orders of magnitude faster within a give…
LOCAL CONTROL OF SOUND IN STOCHASTIC DOMAINS BASED ON FINITE ELEMENT MODELS
2011
A numerical method for optimizing the local control of sound in a stochastic domain is developed. A three-dimensional enclosed acoustic space, for example, a cabin with acoustic actuators in given locations is modeled using the finite element method in the frequency domain. The optimal local noise control signals minimizing the least square of the pressure field in the silent region are given by the solution of a quadratic optimization problem. The developed method computes a robust local noise control in the presence of randomly varying parameters such as variations in the acoustic space. Numerical examples consider the noise experienced by a vehicle driver with a varying posture. In a mod…
Efficient Time Integration of Maxwell's Equations with Generalized Finite Differences
2015
We consider the computationally efficient time integration of Maxwell’s equations using discrete exterior calculus (DEC) as the computational framework. With the theory of DEC, we associate the degrees of freedom of the electric and magnetic fields with primal and dual mesh structures, respectively. We concentrate on mesh constructions that imitate the geometry of the close packing in crystal lattices that is typical of elemental metals and intermetallic compounds. This class of computational grids has not been used previously in electromagnetics. For the simulation of wave propagation driven by time-harmonic source terms, we provide an optimized Hodge operator and a novel time discretizati…
JIMWLK and beyond: From concepts to observables
2016
Volume: 112 Host publication title: 6th International Conference on Physics Opportunities at an Electron-Ion Collider The Color Glass Condensate and its associated evolution equation, the JIMWLK equation have applications to many observables far beyond totally inclusive observables. The phenomenology is so rich that little has been done to explore beyond scaling behavior of correlators. We show first examples that exemplify the considerations necessary to access additional information both experimentally and theoretically and demonstrate that the Wilson line correlators appearing throughout make it imperative to consistently take into account that one is dealing with correlators of group el…
Teachers’ situational physiological stress and affect
2023
Since teaching is a demanding and stressful profession, the study of teachers’ physiological stress in the classroom setting is an emerging field. In cross-sectional studies self-reported stress and affect are related, but less is known about the intraindividual relations between situational physiological stress and corresponding positive and negative affect. The aim of our study was to investigate the associations between situational physiological stress (six salivary cortisol samples per day) and self-reported situational affect (Positive and Negative Affect Schedule four times a day) among 61 Finnish primary school teachers over two workdays. We present a novel multilevel structural equa…
Efectos del capital psicológico en el comportamiento innovador
2013
Este trabajo analiza el impacto del Capital Psicológico del líder sobre el Comportamiento Innovador de los colaboradores en la organización, estableciendo la influencia que en ello tienen los factores Capacidad de Aprendizaje Organizacional y Apoyo o Intercambio entre los miembros del Equipo (Team Member Exchange). El Capital Psicológico, un constructo de segundo orden que incorpora los recursos psicológicos positivos, eficacia, esperanza, optimismo y resiliencia, tiene la posibilidad de construirse sobre el individuo, a diferencia de otros rasgos de la personalidad que normalmente son permanentes en el tiempo, permitiendo a la organización un desarrollo continuado y un impacto favorable en…
Are quality management practices enough to improve process innovation?
2015
The popularity of quality management as a system for continuous improvement has not been accompanied by deep theoretical understanding of its effects on process innovation. In this work, the resource-based view serves as the basis for the construction of a model designed to explain the effects of quality management practices (QMP) on process innovation performance and the mediating role of dynamic capabilities in this relationship. The empirical data were analysed using the structural equation modelling technique by examining 6 competing models that represent full, partial mediation and non-mediation relationships on a sample of 550 Spanish industrial companies. The findings indicate that t…