With the development of technologies in recent decades and the imposition of international standards to reduce greenhouse gas emissions, car manufacturers have turned their attention to new technologies related to electric/hybrid vehicles and electric fuel cell vehicles. This paper focuses on electric fuel cell vehicles, which optimally combine the fuel cell system with hybrid energy storage systems, represented by batteries and ultracapacitors, to meet the dynamic power demand required by the electric motor and auxiliary systems. This paper compares the latest proposed topologies for fuel cell electric vehicles and reveals the new technologies and DC/DC converters involved to generate up-to-date information for researchers and developers interested in this specialized field. From a software point of view, the latest energy management strategies are analyzed and compared with the reference strategies, taking into account performance indicators such as energy efficiency, hydrogen consumption and degradation of the subsystems involved, which is the main challenge for car developers. The advantages and disadvantages of three types of strategies (rule-based strategies, optimization-based strategies and learning-based strategies) are discussed. Thus, future software developers can focus on new control algorithms in the area of artificial intelligence developed to meet the challenges posed by new technologies for autonomous vehicles.

Summary A comprehensive 3D, multiphase, and nonisothermal model for a proton exchange membrane fuel cell has been developed in this study. The model has been used to investigate the effects of the size of the parallel‐type cathode flow channel on the fuel cell performance. The flow‐field plate, with the numerically predicted best performing cathode flow channel, has been built and experimentally tested using an in‐house fuel cell test station. The effects of the operating conditions of relative humidity, pressure, and temperature have also been studied. The results have shown that the fuel cell performs better as the size of the cathode flow channel decreases, and this is due to the increased velocity that assists in removing liquid water that may hinder the transport of oxygen to the cathode catalyst layer. Further, the modelled fuel cell was found to perform better with increasing pressure, increasing temperature, and decreasing relative humidity; the respective results have been presented and discussed. Finally, the agreement between the modelling and the experimentally data of the best performing cathode flow channel was found to be very good.

Since mid 2010, petrol consumption in the transport sector has increased at a higher rate than in other sectors. The transport sector generates 35% of the total CO2 emissions. In this context, strategies have been adopted to use clean energy, with electromobility being the main directive. This paper examines the possibility of charging electric vehicle batteries with clean energy using solar autochthonous renewable resources. An isolated system was designed, dimensioned, and simulated in operation for a charging station for electric vehicles with photovoltaic panels and batteries as their main components. The optimal configuration of the photovoltaic system was complete with improved Hybrid Optimization by Genetic Algorithms (iHOGA) software version 2.4 and we simulated its operation. The solar energy system has to be designed to ensure that the charging station always has enough electricity to supply several electric vehicles throughout all 24 h of the day. The main results were related to the energy, environmental, and economic performance achieved by the system during one year of operation.

One of major current technical challenges in proton exchange membrane water electrolysis (PEMWE) is limited proton conductivity. Nowadays, graphene is considered one of the most promising candidates for improving the ionic transport properties, isotopic selectivity and proton conductivity throughout the unique two-dimensional structure. In this paper, we report on the development of graphene modified commercial membranes (Fumapem®) containing different graphene loadings for PEMWE applications. The membranes are characterized by Scanning Electron Microscopy (SEM) and thermo-gravimetrical and differential thermal analysis (TGA-DSC). Properties of composite membranes are investigated, including water uptake and ionexchange capacity (IEC). In plane four-electrode arrangement is used to determine the proton conductivity of the composite membranes. It is found that composite membranes show an improved behaviour when compared to pristine commercial membranes and graphene loading can improve proton conductivity. In our conditions, the calculated activation energy (Ea) for proton conduction is found to be about 3.80 kJ mol -1 for the composite Fumapem®/graphene membrane with 10 mg graphene loading, lower than of the pristine polymer proton exchange membrane.

Recent environmental and climate change issues make it imperative to persistently approach research into the development of technologies designed to ensure the sustainability of global mobility. At the European Union level, the transport sector is responsible for approximately 28% of greenhouse gas emissions, and 84% of them are associated with road transport. One of the most effective ways to enhance the de-carbonization process of the transport sector is through the promotion of electric propulsion, which involves overcoming barriers related to reduced driving autonomy and the long time required to recharge the batteries. This paper develops and implements a method meant to increase the autonomy and reduce the battery charging time of an electric car to comparable levels of an internal combustion engine vehicle. By doing so, the cost of such vehicles is the only remaining significant barrier in the way of a mass spread of electric propulsion. The chosen method is to hybridize the electric powertrain by using an additional source of fuel; hydrogen gas stored in pressurized cylinders is converted, in situ, into electrical energy by means of a proton exchange membrane fuel cell. The power generated on board can then be used, under the command of a dedicated management system, for battery charging, leading to an increase in the vehicle's autonomy. Modeling and simulation results served to easily adjust the size of the fuel cell hybrid electric powertrain. After optimization, an actual fuel cell was built and implemented on a vehicle that used the body of a Jeep Wrangler, from which the thermal engine, associated subassemblies, and gearbox were removed. Once completed, the vehicle was tested in traffic conditions and its functional performance was established.

Heavy metal pollution of river freshwater environments currently raises significant concerns due to the toxic effects and the fact that heavy metal behavior is not fully understood. This study assessed the contamination level of eight heavy metals and trace elements (Cr, Ni, Cu, Zn, As, Pb, Cd, and Hg) in the surface sediments of 19 sites in 2018 during four periods (March, May, June, and October) in Olt River sediments. Multivariate statistical techniques were used, namely, one-way ANOVA, person product-moment correlation analysis, principal component analysis, hierarchical cluster analysis, and sediment quality indicators such as the contamination factor and pollution load index. The results demonstrated higher contents of Ni, Cu, Zn, As, Pb, Cd, and Hg, with values that were over 2.46, 4.40, 1.15, 8.28, 1.10, 1.53, and 3.71 times more, respectively, compared with the national quality standards for sediments. We observed a positive significant statistical correlation (p < 0.001) in March between elevation and Pb, Ni, Cu, Cr, and Zn and a negative correlation between Pb and elevation (p = 0.08). Intermetal associations were observed only in March, indicating a relationship with river discharge from spring. The PCA sustained mainly anthropogenic sources of heavy metals, which were also identified through correlation and cluster analyses. We noted significant differences between the Cr and Pb population means and variances (p < 0.001) for the data measured in March, May, June, and October. The contamination factor indicated that the pollution level of heavy metals was high and significant for As at 15 of the 19 sites. The pollution load index showed that over 89% of the sites were polluted by metals to various degrees during the four periods investigated. Our results improve the knowledge of anthropogenic versus natural origins of heavy metals in river surface sediments, which is extremely important in assessing environmental and human health risks and beneficial for decision-maker outcomes for national freshwater management plans.

We investigated a simple, reliable radiocarbon measurement procedure for water samples using the direct absorption method for sample preparation, followed by low-level liquid scintillation spectrometry. This process has involved quantitative evaluation of the conversion steps in order to estimate the appropriate working parameters. The 14 C activity of dissolved inorganic carbon (DIC) for several types of water (ranging from seawater to groundwater) has been measured, paying attention to the preparation requirements of each type of water. The main advantage of this method is the simplified sample preparation, allowing measurement of a great number of samples in less time. This method was designed for routine analysis of water samples, and it is proposed particularly for use in 14 C monitoring programs of CANDU-type reactors.'Corresponding author. Email: cvarlam@icsi.ro.

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