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Abstract Fuel cells convert the chemical energy present in fuel (e.g., hydrogen) into electrical energy with high efficiency, low pollution and low noise. Of the various types of fuel cells, the solid oxide fuel cell (SOFC) was developed specifically for power plants and residual power systems. SOFCs are classified into three categories based on their shape: planar, cylindrical and flat-tube. The flat-tube SOFC (FT-SOFC) exhibits the advantages of ease in sealing, low stack volume and low current-collecting resistance. However, due to its weak strength, the FT-SOFC may get deformed or break during the manufacturing process. To improve the cell strength, the cell support must be thickened. However, as the support thickness is increased, the electrons must travel a longer distance, which leads to an increase in the electrical resistance. In another method, the hydrogen channel diameter can be reduced for the strong strength. But, it may lead to a corresponding decrease in the hydrogen mass transfer rate. In this manuscript, we study the performance of several FT-SOFC designs and suggest the better design. The numerical analysis for the FT-SOFC incorporates several physical phenomena such as gas flow, heat transfer and electrochemical reactions. The governing equations (i.e., mass, momentum, energy and species balance equations) are calculated for heat and mass transfer. The open circuit voltage, activation polarization, ohmic polarization and contact resistance are simulated simultaneously. The experimental results are compared with the numerical data for the purposes of code validation. The current density and temperature distribution are then investigated on the SOFC surface. The average current density decreases by 14.6% if the hydrogen channel diameter is narrowed by 50%, and by 10.2% if the support thickness is increased by 50%. Based on these results, we present a design for a stack of FT-SOFCs.

Historically coral reefs of Bahrain were among the most extensive in the southern basin of the Arabian Gulf. However, Bahrain's reefs have undergone significant decline in the last four decades as a result of large-scale coastal development and elevated sea surface temperature events. Here we quantitatively surveyed six sites including most major coral reef habitats around Bahrain and a reef located 72 km offshore. Fleshy and turf algae now dominate Bahrain's reefs (mean: 72% cover), and live coral cover is low (mean: 5.1%). Formerly dominant Acropora were not observed at any site. The offshore Bulthama reef had the highest coral cover (16.3%) and species richness (22 of the 23 species observed, 13 of which were exclusive to this site). All reefs for which recent and historical data are available show continued degradation, and it is unlikely that they will recover under continuing coastal development and projected climate change impacts.

Abstract We fabricated silicon–germanium (Si1−xGex) based HIT solar cells with x = 0, 0.25, 0.41 and 0.56 in order to quantify the effect of germanium fraction on key solar cell performance parameters. The p-type absorber layer consists of 2 and 4 μm Si1−xGex layer grown on p+ silicon substrate using a graded buffer layer to reduce the threading dislocation density. The emitter is n+ amorphous-Si. A thin strained-Si layer is grown on the c-Si1−xGex layer prior to a-Si deposition and is believed to improve a-Si–H/c-Si1−xGex interface quality. The short-circuit current (Jsc) increases, from ∼14 mA/cm2 for Si cells to 21 mA/cm2 for Si0.44Ge0.56 cells with 2 μm-thick active layers, while open-circuit voltage decreases. The spectral response of the Si1−xGex solar cells improves due to a reduction in absorption depth and smaller band-gap associated with the higher germanium fractions.

The mechanisms, figures of merit, and systems for wearable power generation are reviewed in this article. Future perspectives lie in breakthrough technologies of fiber electronics, fully printable, flexible SoC, and IoT-enabled self-awareness systems.

A lake sediment record from the north-eastern European Russian Arctic was examined using palaeolimnological methods, including subfossil chironomid and diatom analysis. The objective of this study is to disentangle environmental history of the lake and climate variability during the past 2000 years. The sediment profile was divided into two main sections following changes in the lithology, separating the limno-telmatic phase between ~2000 and 1200 cal. yr BP and the lacustrine phase between ~1200 cal. yr BP and the present. Owing to the large proportion of semi-terrestrial chironomids and poor modern analogues, a reliable chironomid-based temperature reconstruction for the limno-telmatic phase was not possible. However, the lacustrine phase showed gradually cooling climate conditions from ~1200 cal. yr BP until ~700 cal. yr BP. The increase in stream chironomids within this sediment section indicates that this period may also have had increased precipitation that caused the adjacent river to overflow, subsequently transporting chironomids to the lacustrine basin. After a short-lived warm phase at ~700 cal. yr BP, the climate again cooled, and a progressive climate warming trend was evident from the most recent sediment samples, where the biological assemblages seem to have experienced an eutrophication-like response to climate warming. The temperature reconstruction showed more similarities with the climate development in the Siberian side of the Urals than with northern Europe. This study provides a characteristic archive of arctic lake ontogeny and a valuable temperature record from a remote climate-sensitive area of northern Russia.

In this paper, an artificial neural network (ANN) based approach is proposed to estimate the capacity fade in lithium-ion (Li-ion) batteries for electric vehicles (EVs). Besides its robustness, stability, and high accuracy, the proposed technique can significantly improve the state-of-charge (SOC) estimation accuracy over the lifespan of the battery, which leads to more reliable battery operation and prolonged lifetime. In addition, the proposed technique allows accurate prediction of the battery remaining service time. Two identical 3.6-V/16.5-Ah Li-ion battery cells were repeatedly cycled with constant current and dynamic stress test current profiles at room temperature, and their discharge capacities were recorded. The proposed technique shows that very accurate SOC estimation results can be obtained provided enough training data are used to train the ANN models. Model derivation and experimental verification are presented in this paper.

Abstract Density functional theory in combination with the nonequilibrium Green's function formalism is used to study the electronic transport properties of MAPbI3, MASnI3 and mixed- MAPb 0.5 Sn 0.5 I3 perovskites (MA–methylammonium). The largest electronic transport is obtained for tin-halide sample due to the delocalization of electronic states in the system. The mixed sample also shows improved transport properties as compared to the lead-halide system. In addition, tin-based perovskites are less sensitive to the spin-orbit interactions, whereas the electronic transport properties of MAPbI3 are strongly affected by the relativistic effects. These findings indicate the possibility of enhancing charge carrier transport in organometallic perovskites by metal atom mixing.

Abstract Saline water such as seawater or brackish water is a potential source for drinking water or for non-potable applications, but the existing desalination techniques are energy intensive. Therefore, there is an urgent need to develop sustainable desalination methods. Microbial desalination cells (MDCs) hold great promise for energy-efficient saline water desalination. In MDCs, electrical energy from wastewater is extracted by taking advantages of microbial extracellular respiration and used to drive desalination. Herein, we have comprehensively reviewed and discussed the potential functions of MDCs, including seawater desalination, brackish water desalination, water softening, hydrogen and chemical production, and groundwater remediation along with wastewater treatment. The role of process parameters in improving the MDC performance was also analyzed. We expect to provide insight into the advantages and limitations of this emerging technology from the aspect of its functions, thereby encouraging more research efforts towards further development and commercialization of MDCs.

Rice husk is a bulky byproduct with a high silica content from rice milling. In this study, the application of an acid-catalyzed ionic liquid (IL) pretreatment was studied for processing rice husks with a rugged structure. The pretreatment conditions were 130°C for 30 min with 1.2 wt% HCl. The results of enzymatic hydrolysis demonstrated that cellulose conversion of HCl-BMIMCl-treated at 48 h was increased by 660.05%, 538.81%, and 376.55% compared with the untreated, HCl-treated, and BMIMCl-treated rice husks, respectively. Composition analysis demonstrated that most of the hemicellulose was removed in the acid-IL combined treatment. Moreover, scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared analyses indicated that the crystalline structure and outer silica layer of the rice husks were efficiently broken up. The results revealed that the HCl-catalyzed dissolution is highly favorable for the industrial application of rick husks in the production of fermentable sugar and high-purity silica.