Search results for "stochastic"
showing 10 items of 1018 documents
Optimization of a Sea Wave Energy Harvesting Electromagnetic Device
2008
This paper presents the optimization of a permanent magnet linear generator directly coupled to sea waves. In order to maximize energy extraction, the stochastic features of the energy source is included in the mathematical model of the system in order to satisfactorily tackle the problem. An optimization procedure which includes the stochastic features of the model is presented and a machine built on the basis of the results of this procedure is shown.
Time-dependent Kohn-Sham approach to quantum electrodynamics
2010
We prove a generalization of the van Leeuwen theorem towards quantum electrodynamics, providing the formal foundations of a time-dependent Kohn-Sham construction for coupled quantized matter and electromagnetic fields. Thereby we circumvent the symmetry-causality problems associated with the action-functional approach to Kohn-Sham systems. We show that the effective external four-potential and four-current of the Kohn-Sham system are uniquely defined and that the effective four-current takes a very simple form. Further we rederive the Runge-Gross theorem for quantum electrodynamics.
Electromagnetic radiated field measurements for partial discharge diagnostic
2004
Recently, improvements have been made in the diagnostic of electrical insulation systems by means of electric Partial Discharge (PD) standard measurements through a stochastic approach in the treatment of the acquired data: in this way, the identification of the defects as well as the separation of multiple defects simultaneously active, have been successfully performed. However, the standard PD measurement process can be affected by the well-known parasitic effects due to conducted noise whose spectrum can have characteristics similar to those of the measured signal. Moreover, the classic PD measurement system have to be suitable assembled on the Device Under Test (DUT) so determining a co…
Spectral Analysis of Nonrelativistic Quantum Electrodynamics
2001
I review the research results on spectral properties of atoms and molecules coupled to the quantized electromagnetic field or on simplified models of such systems obtained during the past decade. My main focus is on the results I have obtained in collaboration with Jurg Frohlich and Israel Michael Sigal [8, 9, 10, 11, 12, 13].
A multiphysics approach to the design of a seawave energy conversion system
2008
This paper presents a multiphysics approach to the design of a seawave energy conversion system which consists of a both a permanent magnet linear generator directly coupled to sea waves and the related power electronics conversion system. The thermal, electromagnetic and circuital aspects are included in the proposed approach. In order to maximize energy extraction, the stochastic features of the energy source is considered in the mathematical model of the whole system. An optimization procedures which includes the stochastic features of the model is presented and a machine built on the basis of the results of this procedure is shown.
A novel frequency domain method for predicting fatigue crack growth under wide band random loading
2007
This work deals with the evaluation of the fatigue crack growth rate of structural components subjected to uniaxial Gaussian stationary wide band random loading. In detail, a new frequency domain method that allows the user to estimate the expected crack growth rate directly from the PSD data is proposed. Using a stochastic mean function properly, introduced and described by simple closed form relationships implemented by systematic numerical simulations of a high number of wide band random processes, the proposed method permits to avoid the onerous time domain simulations and provides in general crack growth rate predictions in a good accordance with the so-called time domain method. Pract…
ECONOMIC-STATISTICAL DESIGN APPROACH FOR A VSSI X-BAR CHART CONSIDERING TAGUCHI LOSS FUNCTION AND RANDOM PROCESS SHIFTS
2014
Economic design approaches of control charts are commonly based on the assumption that various cost parameters values and the occurrence risk of assignable causes have to be a priori known with precision. However, in real operative contexts, such parameters can be really difficult to accurately estimate, especially considering costs arising from out-of-control conditions of the process. As consequence, pure economic design approaches can involve chart schemes with low statistical performance. To overcome such limitation, it is herein proposed a multi-objective economic-statistical design approach for an adaptive X-bar chart. In particular, such approach aims at the minimization of both the…
Multicriteria evaluation of sustainable energy solutions for Colosseum
2017
Abstract Colosseum is a large office building in the capital region of Finland. The building owner operates on the highly competitive office rental market. With increasing emphasis on environmental responsibility, energy efficiency and sustainable energy solutions can provide competitive edge on the rental market. This study evaluates in terms of multiple criteria different alternatives to enhance the energy solutions of the building. The alternatives included different configurations of solar power, ground source heat, and roof constructions, along with district heating. Decision criteria included internal rate of return, energy efficiency, CO2 emissions, and attractiveness. Attractiveness…
Influence of material properties variability on springback and thinning in sheet stamping processes: a stochastic analysis
2010
A very critical issue for stamping operations is the improvement of process robustness. The reliability of final results, in fact, strongly depends on the intrinsic variability due to stochastic behavior of many parameters, namely, operative ones and material properties. A given process performance may undergo a variation around the value which would be obtained neglecting stochastic behaviors of the operative or material parameters (i.e., considering a deterministic parameters behavior). Such variation introduces a significant source of uncertainty within the process design: a possible consequence may be the rejection of some stamped parts. In this paper, reliability analyses aimed to evid…
Contribution to the platoon distribution analysis in steady-state traffic conditions
2014
The traffic flow analysis and the relevant vehicle distribution (“free-moving” or “platooned” vehicles) on highway facilities at uninterrupted flow has always had fundamental importance in Highway Engineering, with special reference to topics like traffic operations, car accidents, road safety and air pollution emissions. In light of this, the study suggests a calculation algorithm as a random test generator to simulate a steady state traffic flow and to provide time headways. Thanks to the outcome produced by numerical simulations, we analysed platoon distributions within traffic flows in a steady-state regime and showed the results of numerical analyses carried out by traffic random proce…