Search results for "FREQUENCY"
showing 10 items of 2158 documents
Configurable bandwidth imaging spectrometer based on acousto-optic tunable filter
2005
This paper presents a new portable instrument called Autonomous Tunable Filtering System (ATFS), developed for highly customisable imaging spectrometry in the VIS-NIR range. The ATFS instrument consists of an Acousto-Optic Tunable Filter (AOTF), an optical system, a Radio Frequency (RF) driver based on a Direct Digital Synthesiser (DDS) and control software. The ATFS can be attached to a variety of high-performance monochrome cameras. The system works as a spectral bandpass filter whose wavelength can be selected between 400nm and 1000nm and whose bandwidth can be adjusted between 4nm and 50nm. The filter can be tuned electronically at a very high speed and accuracy, thanks to the DDS versa…
A simulation model for electromagnetic transients in lightning protection systems
2002
This paper deals with the evaluation of electromagnetic transients in a lightning protection system (LPS). A field approach is used, based on the numerical solution of a modified version of the thin-wire electric field integral equation in the frequency domain. Time profiles of interesting electromagnetic quantities are computed by using a discrete fast Fourier transform algorithm. The model takes into account coupling effects among aerial parts and ground electrodes in order to correctly estimate the quantities which can determine electromagnetic hazard inside the LPS; transient touch and step voltages can be easily evaluated also taking into account the human body presence on the soil sur…
Simple equipment to measure biomechanical quantities of muscles and organs which includes a polarity-programmable peak detector
1982
Biomechanical measurements of muscles and organs require appropriate measuring equipment. As far as the static properties are concerned, the excursion of the bender bar of stress should be without force. The bender bar of force, however, ideally should not elongate under load. Because natural frequency is the most important boundary condition, the bender bar should be developed with this in mind. The developed bars imposed an insignificant preload to the muscle or to the organ. The small changes in resistance occurring in the resistance strain gauges affixed to the bars require the use of a highly stable amplifier. A new amplifier was accordingly developed based on the principle of an instr…
Frequency stability in microgrid: control strategies and analysis of BESS aging effects
2016
In order to ensure a thorough analysis, all components placed in a microgrid would have to be considered to guarantee an effective energy management. To this aim, various algorithms are used both to preserve and restore power systems after significant disturbances. However, these models frequently do not evaluate components performance decline with the age and, consequently, they don't consider actual values during microgrid analysis, potentially affecting obtained results. In particular, evaluating energy storage systems aging and their effects has rarely been addressed in prior works. The present article proposes a model to maintain power system/microgrid stability after disturbances usin…
UMTS radio networks
2006
Publisher Summary This chapter reviews the contributions to the UMTS radio network planning, with the optimization being provided from COST 273 and the real-time tuning, which is related to RRM. The results on UTRAN performance evaluation by the means of simulation tools are also discussed. The UMTS planning includes processes like: the propagation and traffic models, the aspects of parameter planning, and the automatic planning algorithms. An accurate ray-tracing model integrated in a UMTS-capable planning tool allows the radio network planner to reach optimal numbers for the BS deployment and configuration while meeting the service level requirements. Ray tracing can identify the problem …
Dynamic characterization for the dielectric electroactive polymer fundamental sheet
2012
Published version of an article published in the journal: International Journal of Advanced Manufacturing Technology. Also available from the publisher at: http://dx.doi.org/10.1007/s00170-012-4423-6 A study into the appropriateness of characterizing the dynamics of the dielectric electroactive polymer (DEAP) fundamental sheet has been performed. Whereby a model describing the dynamics of the DEAP fundamental sheet is developed, parameters of the models are determined using experimental/simulation results, and verification has been conducted to determine the precision of the dynamic model. The precision for the DEAP sheet-obtained dynamic model could not be verified unless some parameters c…
RF-based node system for blind navigation in running activities
2008
The system presented is oriented for use by blind adults or children in running activities at a stadium or an analogical large space. The system dynamically provides a blind person with navigation related information. Radio signal strength measurements are used in localization task. The system makes a blind person more independent in sport, eliminating the need in explicit human assistance.
Quasi-digital conversion for resistive devices: application in GMR-based IC current sensors
2013
Resistive devices, including sensors, are used in a huge range of applications within different scenarios. When a complete system is considered, a quasi-digital output is often recommendable. If the conversion is operated at device level, some problems such as noise disturbs, insertion losses and so on, can be reduced. In this work, we describe a resistance-tofrequency (R-f) converter with a suggested application in low current monitoring by means of GiantMagnetoResistance (GMR) sensors. Specific devices have been designed and microfabricated. The system has been tested by means of discrete components with a PCB. The complete microsystem monolithic integration in a standard CMOS technology …
Electric Power Quality Evaluation in the Presence of Electromagnetic Emissions
2013
The measurements for the assessment of the electric power quality are often carried out in hostile electromagnetic environments. The aim of the paper is analyzing if and how both radiated and conducted electromagnetic emissions can disturb the measurement system used to quantify these disturbances. To achieve the target, an experimental approach is proposed, which, by means of a simple and fast test, allows establishing if the real electromagnetic environment, where power quality analysis is performed, can alter the measurements. © 2013 IEEE.
Influence of the channel design on the heat and mass exchange of induction channel furnace
2011
PurposeThe purpose of this paper is to present in‐depth numerical modelling of heat and mass exchange in industrial induction channel furnace (ICF).Design/methodology/approachThe turbulent heat and mass exchange in the melt is calculated using a three‐dimensional (3D) electromagnetic model and a 3D transient large eddy simulation method. The simulation model has been verified by flow velocity and temperature measurements, which were carried out using an industrial sized channel inductor operating with Wood's metal as a low temperature model melt.FindingsThe ICF is well‐established for melting, holding and casting in the metallurgical industry. But there are still open questions regarding th…