Search results for "methods"

TORSIONAL STRESS CONCENTRATIONS IN SHAFTS: FROM ELECTRICAL ANALOGIES TO NUMERICAL METHODS

2013

This paper presents the historical development of methods used for the study of torsional stresses in shafts. In particular the paper covers both analog methods, in particular those based on electrical analogies proposed since about 1925, and numerical methods, in particular finite difference methods (FDM), finite element methods (FEM) and boundary elements (BEM).

An optimization procedure for the friction stir welding FEM model of corner fillet joints

2012

Friction stir welding (FSW) is an energy efficient and environmentally "friendly" (no fumes, noise, or sparks) welding process, during which the sheets are welded together in a solid-state joining process. FSW is mature for simple configurations but a significant lack of knowledge is found when dealing with different designs such as T-sections, box sections and corner welds. Although the latter joint morphology has traditionally been considered unfeasible for the process, it seems to have a great potential to be used also for T-joint configurations, a recurrent design pattern in transport applications. A specific tool has been developed and a set of experimental welds has been produced with…

Nanostructured Materials Obtained by Electrochemical Methods: From Fabrication to Application in Sensing, Energy Conversion, and Storage

2020

It is well known that physical and surface properties of nanomaterials are promising to enhance efficiency of nanostructured devices for sensing and for sustainable energy production, conversion, and storage. However, the practical use of nanomaterials is often complicated by the lack of scalable and cost-efficient synthesis procedures and the challenge of integrating into devices 1D nanomaterials saving their structural features. In this field, one of the most severe challenges is to find suitable methods for fabricating nanomaterials. Over the years, numerous preparation methods were proposed in the literature, but not all of them are easily scalable and economically advantageous for indu…

An Improved Solver for the M/EEG Forward Problem

2014

Noninvasive investigation of the brain activity via electroencephalography (EEG) and magnetoencephalography (MEG) involves a typical inverse problem whose solution process requires an accurate and fast forward solver. We propose the Method of Fundamental Solutions (MFS) as a truly meshfree alternative to the Boundary Element Method (BEM) for solving the M/EEG forward problem. The solution of the forward problem is obtained, via the Method of Particular Solutions (MPS), by numerically solving a set of coupled boundary value problems for the 3D Laplace equation. Numerical accuracy and computational load are investigated for spherical geometries and comparisons with a state-of-the-art BEM solv…

Bio-electromagnetic Numerical Modeling for Health Diagnostics

A Backward Method for Solving PV Nodes in Weakly Meshed Distribution Networks

2007

In this paper, a new iterative backward/forward methodology for the load flow solution of weakly meshed systems with fixed voltage nodes is presented. Such technique models the loads at each iteration by means of impedances, and the PV nodes by means of reactances. Each iteration is organised in two steps. In the first, the radial network attained from the meshed system through cuts and composed of shunt and series impedances is solved. In the second step, based on a reduced Thévenin impedance matrix, the compensation currents to be injected in the cut nodes are deduced. Modelling the PV nodes by means of reactances allows the attainment, for the reactive power of these nodes, of the same p…

An analytical model for PQ sources in backward/forward methods for distribution networks analysis

2004

In this paper a model of PQ sources useful for distribution systems analysis is developed. In the considered systems there are, in addition to HV/MV sources, other PQ buses, namely active and reactive power supply nodes (Vδ nodes). The general solution strategy is an iterative forward/backward method, in which the state variables are the node voltages. If it is weakly meshed, the network is turned into radial by means of cuts and compensation currents. After the presentation of the general problem, the equations expressing the unknowns for the PQ nodes are treated in detail. These equations belong to the backward sweep of the algorithm. The methodology has been implemented and applied so as…

A new model of PV nodes in distribution networks backward/forward analysis

2004

In this paper a new model of PV nodes is developed; the model is aimed for the distribution systems load flow analysis and, in particular, for the iterative forward/backward method. If the network is weakly meshed, it is turned into radial by means of cuts and compensation currents. After the presentation of the general problem and the state of the art on the subject, the equations expressing the unknowns for the PV nodes are treated in detail. These equations belong to the forward sweep of the algorithm. The methodology has been implemented and applied so as to test its performance in terms of calculation times and precision. The obtained results confirm the efficiency of the proposed appr…

Application to an italian distribution system of a multiobjective optimal Volt/VAR control strategy: improvements and management problems

2007

In this paper, the experiences and results deriving from the application of a multiobjective optimal management strategy to a distribution network supplying an area in province of Palermo, Italy, are presented. The adopted strategy allows, through the interventions on the Under Load Tap Changers (ULTC) of the primary substations and on tie-switches, to reduce power losses and improve the voltage profiles. To solve the optimization problem, an evolutionary approach has been adopted; it employs fuzzy logic for an adequate and simultaneous fulfilment of the different objectives. The application section presents a deep technical and economical analysis of the results attained, applying the opti…

An Adaptive Bayesian System for Context-Aware Data Fusion in Smart Environments

2017

The adoption of multi-sensor data fusion techniques is essential to effectively merge and analyze heterogeneous data collected by multiple sensors, pervasively deployed in a smart environment. Existing literature leverages contextual information in the fusion process, to increase the accuracy of inference and hence decision making in a dynamically changing environment. In this paper, we propose a context-aware, self-optimizing, adaptive system for sensor data fusion, based on a three-tier architecture. Heterogeneous data collected by sensors at the lowest tier are combined by a dynamic Bayesian network at the intermediate tier, which also integrates contextual information to refine the infe…