Search results for "Condition"
showing 10 items of 2530 documents
Numerical Modelling of Room Thermal Comfort Conditions
2006
Particular heat transfer coefficients of building elements gives quantitative notion only about heat losses through this building element. Analysis of the overall heat balance and heat losses of complete building and study of particular contribution of building elements in overall balance allows one to figure out the state of the building and find the building elements of bounding construction with most significant heat losses. Project variants of the buildings (or rebuilding in case of renovation), which ensure the desirable economy of energy and proportions of investments can be find varying the proportions of the surface area of building elements (e.g., windows and doors). A lot of facto…
Innovative algorithms for the management of combined RES-BESS systems
2017
The issue of the optimal management of the available energy resources also at end-user level is getting more and more attention. The paper deals with the definition of innovative algorithms for managing electrical storage systems in hybrid photovoltaic and wind plants, also taking into account different pricing periods and a grid emergency condition in which the Utility can request an injection of power by the end-user. Application examples for explaining the operation of the algorithms are presented.
Vibration signature analysis for monitoring rotor broken bar in double squirrel cage induction motors based on wavelet analysis
2014
Purpose – The purpose of this paper is to present a diagnosis technique, for rotor broken bar in double cage induction motor, based on advanced use of wavelet transform analysis. The proposed technique is experimentally validated. Design/methodology/approach – The proposed approach is based on a combined use of frequency sliding and wavelet transform analysis, to isolate the contribution of the rotor fault components issued from vibration signals in a single frequency band. Findings – The proposed technique is reliable for tracking the rotor fault components over time-frequency domain. The quantitative analysis results based on this technique are the proof of its robustness. Research limit…
A novel approach to current transformer characterization in the presence of harmonic distortion
2009
The current transformer (CT) performance under distorted waveform conditions is usually characterized by means of the frequency-response test. In this paper, a new way to characterize CTs, closer to real operation conditions, is proposed. The harmonic phase-angle and ratio errors are measured using a nonsinusoidal current composed of fundamental and one harmonic with adjustable phase shift. The new method was tested by determining the performance of two metering class CTs commonly used by the Italian power company. The errors measured using the proposed approach are larger than the ones obtained with the frequency response. This result suggests that the frequency-response approach for the e…
You cannot speak and listen at the same time: a probabilistic model of turn-taking.
2017
Turn-taking is a preverbal skill whose mastering constitutes an important precondition for many social interactions and joint actions. However, the cognitive mechanisms supporting turn-taking abilities are still poorly understood. Here, we propose a computational analysis of turn-taking in terms of two general mechanisms supporting joint actions: action prediction (e.g., recognizing the interlocutor's message and predicting the end of turn) and signaling (e.g., modifying one's own speech to make it more predictable and discriminable). We test the hypothesis that in a simulated conversational scenario dyads using these two mechanisms can recognize the utterances of their co-actors faster, wh…
A Simple Method for Evaluating Ground-Fault Current Transfer at the Transition Station of a Combined Overhead-Cable Line
2008
When a substation is fed by a combined overhead-cable transmission line, a significant part of the ground fault current flows through cable sheaths and is discharged into the soil at the transition station where cables are connected to the overhead line. Such a phenomenon, known as ldquofault application transfer,rdquo may result in high ground potentials at the transition station which may cause shocks and equipment damage. The scope of this paper is to present new analytic formulas which can be used for the direct calculation of the fault current transferred at the transition station and its ground potential rise as well as the substation earth current. The proposed formulas allow evaluat…
Environmental, functional and economic criteria for comparing “target roundabouts” with one- or two-level roundabout intersections
2015
The article describes a criterion based on functional, environmental and economic aspects for comparing conventional roundabouts with innovative one- or two-level roundabouts. We compared the performances of eight roundabout types, differing in geometric layout, number of lanes and traffic flow regulation from each other, with regard to vehicle delays and CO2, NOx, PM2.5 and PM10 pollutant emissions. Recently-designed roundabouts - target roundabouts and flyover roundabouts - have also been studied for their undoubted practical interest. By means of closed-form capacity models and CORINAIR methodology, several traffic simulations were carried out to examine a typical annual traffic demand c…
Short-term prediction of household electricity consumption: assessing weather sensitivity in a Mediterranean area
2008
Abstract Urban microclimatic variations, along with a rapid reduction of unit cost of air-conditioning (AC) equipments, can be addressed as some of the main causes of the raising residential energy demand in the more developed countries. This paper presents a forecasting model based on an Elman artificial neural network (ANN) for the short-time prediction of the household electricity consumption related to a suburban area. Due to the lack of information about the real penetration of electric appliances in the investigated area and their utilization profiles it was not possible to implement a statistical model to define the weather and climate sensitivities of appliance energy consumption. F…
APPLICATION OF MATHEMATICAL MODELS FOR THE SIMULATION OF THERMAL COMFORT CONDITIONS IN A LIVING ROOM
2005
The paper deals with the distributions of temperature and averaged turbulent airflows in living rooms in 2D and 3D approximations using Ansys/Flotran and Ansys/CFX software respectively. The distributions are calculated depending on the placement and temperature of heaters, heat transfer coefficients of the building structures and ventilation conditions. The authors analyse the influence of these factors on the air circulation and the related heat flows through building structures. The thermal balance of a room and its dependence on various external factors is also considered. As thermal comfort conditions’ parameters are analysed, the airflow velocities and indoor temperatures with its gra…
Analysis of Air Cycle and Efficiency Evaluation for a Blast Freezing Tunnel Plant
2013
Air refrigerating systems offer a suitable alternative to vapour compression systems. Air can be used as working fluid in gas compression cycles for refrigeration, air conditioning and heat pump systems. This paper gives some results of theoretical investigation into improved air cycles for refrigeration systems and a comparison is made with their performances. The case-study relates to a dual purpose refrigerating plant. A blast freezing tunnel gives the coldest air stream and, in cascade, the air coming out from the tunnel is used in a channel network for feeding a lot of chilling cells. The case-study analysed indicates that there is a real possibility to build plants which will be equip…