Proton exchange membrane fuel cell operation and degradation in short-circuit.

International audienceThis paper presents an experimental study dealing with operation and degradation during an electrical short circuit of a proton exchange membrane fuel cell stack. The physical quantities in the fuel cell (electrical voltage and current, gas stoichiometry, pressures, temperatures and gas humidity) are studied before, during and after the failure. After a short circuit occurs, a high peak of current appears but decreases to stabilize in a much lower value. The voltage drops in all the cells and even some cells presents reversal potentials. The degradation is quantified by using electrochemical impedance spectroscopy

Factor structure and factorial invariance of the strengths and difficulties questionnaire among children of prisoners and their parents

Parental imprisonment has been linked to a variety of adverse psychological outcomes for children and adolescents. The Strengths and Difficulties Questionnaire (SDQ) has been widely used to assess behavioural and emotional difficulties among 7-17 year olds in the general population and more recently has been utilised among samples of children of prisoners. Previous research has variously tested traditional one-, three- and five- factor solutions to the SDQ, and more recently one bifactor solution has been examined. Based on a sample of children of prisoners (N = 724) and their non-imprisoned parent or caregiver (N = 658), the aim of the present study was to simultaneously compare nine alternative factor structures, including previously tested models and alternative bifactor solutions. Tests of factorial invariance and composite reliability were also performed. The five-factor model was found to provide the best fit for the data. Tests of factorial invariance revealed that the five-factor model provided an equally acceptable, but not identical fit, among boys and girls. Composite reliability scores were low for the Conduct Problems and Peer Problems subscales. The utility of the SDQ in measuring psychological functioning in response to parental imprisonment is discussed

Children of Prisoners: Their Situation and Role in Long-Term Crime Prevention

Studies suggest that maintaining family ties can help reduce the likelihood of reoffending, and that while parental imprisonment can increase a child’s likelihood to offend, positive responses to the situation can aid the children’s well-being, attitude and attainment. Drawing on findings from the recently completed EU-funded COPING Project on the mental health of children of prisoners, this chapter explores the factors that aid a child’s ability to cope with parental imprisonment and the actions that different stakeholders can take to support them. It identifies some of the mental health impacts at different stages of parental imprisonment, the roles played by non-imprisoned parents/carers and by schools, and suggests options for further clarifying the factors that help and hinder children of prisoners in the short and long term

On-line energy management for HEV based on particle swarm optimization

This study considers a Hybrid Electrical Vehicle supplied by a Fuel Cell stack and supercapacitors used as Storage Element. In such an application, real time energy management is of paramount importance in order to increase autonomy and be able to deal on-line with perturbed power demand. Many offline power flow optimization principles are available but online algorithms are preferred and should be derived for optimal management of the instantaneous power splitting between the different available power sources. Based on particle swarm optimization algorithm, this study defines the parameters tuning of such algorithm. The final power splitting allows not only recovering energy braking but also is robust to some disturbances occurring during the trip. The solution provides good-quality and high-robustness results in a certain class of mission profile and power disturbance

Fault Diagnosis and Identification of Proton Exchange Membrane Fuel Cell System Using Electrochemical Impedance Spectroscopy Classification

This paper deals with fault diagnosis of a Proton Exchange Membrane Fuel Cell (PEMFC) using a supervised method of classification coupled with Electrochemical Impedance Spectroscopy (EIS). The purpose is to be able to detect if the fuel cell is in abnormal operating conditions and also to isolate the fault. To reach this aim, a classification method is tested on three different stacks, from different electrical power levels. The results exhibit good performances and an acceptable calculation time what can allow to make some on-line diagnosis

EMR modelling of a hydrogen-based electrical energy storage

This paper deals with multi-physics modelling of the stationary system. This modelling is the first step to reach the fuel cell system dimensioning aim pursued. Besides this modelling approach based on the stationary energetic system, the novelty in this paper is both the new approach of the photovoltaic EMR modelling and the EMR of the hydrogen storage process. The granular modelling approach is used to model each component of the system. Considering a stand alone PEM fuel cell system, hydrogen is expected to be produced and stored on the spot from renewable energy (photovoltaic) in order to satisfy the fuel availability. In fact, to develop a generic and modular model, energetic macroscopic representation (EMR) is used as graphical modelling tool. Allowing to be easily grasped by the experts even not necessarily gotten used to the modelling formalism, EMR is helpful to model the multi-domains energetic chain. The solar energy through solar module is converted in electrical energy; part of this energy is transformed in chemical energy (hydrogen) thanks to an electrolyser. Then the hydrogen is compressed into a tank across a storage system. The latter part of the solar module energy is stored as electrical energy within supercapacitor or lead-acid battery. Using the modularity feature of the EMR, the whole system is modelled entity by entity; afterwards by putting them together the overall system has been reconstructed. According to the scale effect of the system entities, some simulation and/or experimental results are given. Given to the different aims which are pursued in the sustainable energy framework like prediction, control and optimisation, EMR modelling approach is a reliable option for the energy management in real time of energetic system in macroscopic point of view

SOFC modelling based on discrete Bayesian network for system diagnosis use

International audienceWe propose in this paper a diagnosis method that is aimed to detect and isolate SOFC system fault by using the FC stack as a sensor. A discrete Bayesian network (BN) was established to illustrate the input-output causal relations of the stack. In order to examine the generalizability of the network structure, the BN was parameterized to fit the experimental data from two different SOFC systems. Themodels showed reasonable accuracy of state estimation for 6 operating variables. Finally, the BN model was experimented for diagnosing a specified system fault