Search results for "Transient"
showing 10 items of 623 documents
Spark ignition feedback control by means of combustion phase indicators on steady and transient operation
2014
In order to reduce fuel cost and CO2 emissions, modern spark ignition (SI) engines need to lower as much as possible fuel consumption. A crucial factor for efficiency improvement is represented by the combustion phase, which in an SI engine is controlled acting on the spark advance. This fundamental engine parameter is currently controlled in an open-loop by means of maps stored in the electronic control unit (ECU) memory: such kind of control, however, does not allow running the engine always at its best performance, since optimal combustion phase depends on many variables, like ambient conditions, fuel quality, engine aging, and wear, etc. A better choice would be represented by a closed-…
Do public employment services affect the self-rated health of migrant workers in China?
2022
Migrant workers greatly contributing to China’s industrialization and urbanization are confronted with increasing health risks. This study empirically investigates the effects of public employment services on the self-rated health of migrant workers in Shanghai China, by using data from the National Bureau of Statistics from 2015 to 2020. The estimation results under the Ordered Probit model illustrate that public employment services significantly improve the self-rated health of migrant workers, and vocational training, job development and other related services show an apparently positive correlation with the self-rated health. The marginal effect analysis reveals that public employment s…
Condiciones de trabajo y salud de los trabajadores inmigrantes en España: revisión bibliográfica
2014
Fundamentos: La relación entre inmigración, trabajo y salud constituye uno de los retos más importantes en salud laboral y más concretamente en España por el importante incremento de proporción inmigrante acontecido en el mercado laboral. El objetivo de esta investigación es conocer la relación entre las condiciones de trabajo y sus efectos en la salud de trabajadores inmigrantes en España. Métodos: Revisión bibliográfica de artículos científicos originales en español e inglés Medline y Medes (1998-2012). Se revisaron los textos completos de los artículos incluidos. Resultados: Se incluyeron 20 estudios, 13 con metodología de investigación cuantitativa y 7 cualitativa. Los temas tratados ab…
TRANSIENT SEMICONDUCTOR DEVICE SIMULATION INCLUDING ENERGY BALANCE EQUATION
1992
An efficient numerical method for the solution of hot‐carrier transport equations describing transient processes in submicrometer semiconductor devices is proposed. The calculations of transient processes in submicrometer MOS transistor were carried out and compared with the results obtained by conventional drift‐diffusion model.
Transient Modelling of Thermal Conditions in Test Buildings Including Radiation
2015
Abstract To increase the energy efficiency of buildings in Latvia's climate a comparative study with five experimental test buildings have been set up in Riga, Latvia. Different thermo physical quantities such as temperature, humidity, air velocity, etc. were monitored to better understand different behaviour of the building envelope. This gives an excellent validation possibility for the CFD model that in future could predict conditions in buildings with different envelopes. Previously a stationary model and transient model were considered without taking into consideration the thermal radiation. This study continues the previous work that was done and proposes a transient model which takes…
Transient stability analysis for symmetrical and unsymmetrical faults in mixed three-phase and six-phase power systems
1989
Abstract The aim of this paper is to analyse the transient stability of a three-phase power system with six-phase lines interconnected by three-phase to six-phase transformers. For these mixed power systems a transient stability analysis is performed under all main types of disturbances (short-circuits, generator and load rejection, line outages), particularly in the case of faults at six-phase buses. A generalized procedure to evaluate transient stability is explained in detail. It is based on the symmetrical components method, which allows one to consider also unsymmetrical faults both at three-phase and six-phase buses. For every possible unsymmetrical short-circuit an equivalent fault a…
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…
Composite nonlinear feedback control for path following of four-wheel independently actuated autonomous ground vehicles
2015
This paper studies the path following control problem for four-wheel independently actuated (FWIA) autonomous ground vehicles (AGVs) through integrated control of active front-wheel steering (AFS) and direct yaw-moment control (DYC). A modified composite nonlinear feedback (CNF) strategy is proposed to improve the transient performance and eliminate the steady-state errors in the path following control considering the tire force saturations, in the presence of the time-varying road curvature for the desired path. The path following is achieved through vehicle lateral and yaw control, i.e., the lateral velocity and yaw rate are simultaneously controlled to track their respective desired valu…
Experimental investigations and numerical modelling of the melting process in the cold crucible
2005
PurposeAims to present recent activities in experimental investigations and numerical modelling of the induction cold crucible installation.Design/methodology/approachTemperature and velocity measurements using thermocouples and electromagnetic velocity probes were performed in aluminium melt which was used as a model melt. Measured temperature field and flow pattern were compared with transient 3D calculations based on large eddy simulation (LES) turbulence modelling scheme. Numerical results are in good coincidence with the experimental data.FindingsThe modelling results show that only 3D transient LES is able to model correctly these heat and mass transfer processes.Originality/valueIt i…
Experimental validation of a general model for three phase inverters operating in healthy and faulty modes
2012
The paper presents the experimental verification of a general mathematical model of Voltage Source Inverters (VSI) able to simulate fault conditions and which is also useful for the simulation of fault-tolerant systems for different applications. In general, in the past, the problem of faulty inverters modeling has been addressed specifically by considering faults on the different phases as separate cases. Furthermore, traditional models include only the faulty mode and not the healthy mode, so resulting then not able to predict transient phenomena. The model hereafter presented overcomes this drawback. It was formulated by introducing the concept of “healthy leg binary variables”. Such var…