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We present a framework to quantify the radiation from tropical cyclones (TCs) in shortwave (SW, wavelength smaller than 3 micron) and longwave (LW, wavelength larger than 3 micron) portions of the electromagnetic spectrum. The framework includes two stages: segmentation of TC clouds and calculation of the radiation effects attributable to TC clouds. The segmentation task is accomplished by an algorithm which takes a time series of brightness temperature images of TCs and uses image processing techniques to acquire segmentation for each image in a semisupervised manner. The radiation is calculated by combining the segmentation results with the cloud and earth's radiant energy system dataset via a coordinate-matching scheme due to their difference in resolution. The framework was implemented to analyze the net contribution of TCs to the upwelling radiation in 2016 and in summer months between 2015 and 2019 at regional and global scales. Results show that both the magnitude and the variability of radiation contribution by TCs are of an order of magnitude that could have a significant effect on the overall earth's energy balance.

Abstract Improved solar cell efficiency is the key to ongoing photovoltaic cost reduction, particularly as economies of scale propel module-manufacturing costs towards largely immutable basic material costs and as installation costs become an increasingly large contributor to total system costs. To enable manufacturers to move past the 20% cell energy conversion efficiency figure in production, high-efficiency PERC (Passivated Emitter and Rear Cell) sequences are being increasingly brought online. Most new photovoltaic manufacturing capacity added in the second half of 2014 was PERC-based, making PERC now the cell technology with second-highest production capacity, with the latest industry roadmap anticipating PERC will become the dominant commercial cell technology by 2020. The first paper describing the PERC cell appeared in 1989, although the structure was conceived several years earlier. The attractive technical features were the reduction of rear surface recombination by a combination of dielectric surface passivation and reduced metal/semiconductor contact area while simultaneously increasing rear surface reflection by use of a dielectrically displaced rear metal reflector. The key issues in the development of this technology and its commercial implementation are described, including a review of recent adoption rates and the way these are likely to evolve in the future.

Choice tests are a standard method to determine preferences in bio-assays, e.g. for food types and food additives such as bait attractants and toxicants. Choice between food additives can be determined only when the food substrate is sufficiently homogeneous. This is difficult to achieve for wood eating organisms as wood is a highly variable biological material, even within a tree species due to the age of the tree (e.g. sapwood vs. heartwood), and components therein (sugar, starch, cellulose and lignin). The current practice to minimise variation is to use wood from the same tree, yet the variation can still be large and the quantity of wood from one tree may be insufficient. We used wood samples of identical volume from multiple sources, measured three physical properties (dry weight, moisture absorption and reflected light intensity), then ranked and clustered the samples using fuzzy c-means clustering. A reverse analysis of the clustered samples found a high correlation between their physical properties and their source of origin. This suggested approach allows a quantifiable, consistent, repeatable, simple and quick method to maximize control over similarity of wood used in choice tests.

The article investigates the impact of aerosol composition on the estimation of the downwelling surface shortwave flux (DSSF). This initiative forms part of the efforts to improve the DSSF distributed by the Land Surface Analysis Satellite Application Facility (LSA-SAF). This operational product assumes invariant aerosol properties under clear sky conditions, which can be inaccurate for some regions of the world. This is the case of West Africa, where aerosol activity is not only highly variable due to frequent dust storms but also rich because of the coexistence of different aerosol species. This study was carried out over the West African stations of Dakar and Niamey, which represent different aerosol scenarios. Several dates during the dry season of 2006 were selected and classified into four different day types according to aerosol activity: standard, clean, mixture and dusty days. The diurnal evolution of DSSF and its direct and diffuse components were estimated for the selected dates by the current LSA-SAF algorithm and two other approaches using aerosol measurements from the Aerosol Robotic Network (AERONET) as input. The first alternative approach took the diurnal evolution of the total aerosol optical depth (AOD) into account, assuming a default desert aerosol type. Experiments with this method showed a significant improvement in the estimated DSSF compared to the current LSA-SAF algorithm. For example, root mean square error (RMSE) improved from 170 W/m2 to 50 W/m2 for dusty days in Dakar and from 73 W/m2 to 21 W/m2 for mixture days in Niamey. This improvement resulted from the consideration of a time-varying AOD, which accounted for the rapidly changing aerosol load for these two day types. The second alternative approach tested included consideration of the diurnal variation of the aerosol load and composition. Again, this was done using AERONET data on the fine and coarse aerosol modes, which may be associated with different sized dust particles, sea salt, or soot from biomass burning (depending on the date). This enhanced consideration of the aerosol composition greatly improved the estimation of the diffuse component of the DSSF, further reducing the RMSE during mixture days from 50 W/m2 to less than 10 W/m2. This improvement mainly came from consideration of the right scattering properties of the aerosol particles, which may be significantly different for each aerosol type.

This study provides a new approach of electrode dependent anaerobic ammonium oxidation (electroanammox) in microbial fuel cell (MFC) integrated hybrid constructed wetlands (CWs). The study was carried out in three CWs, each with a horizontal flow (HF) followed by a vertical upflow (VUF). Two of the CWs were integrated with MFC, one was operated in closed circuit (CL) mode and the other in open circuit (OP) mode to determine the influence of electron transfer through an external electrical circuit. The initial nitrogen and carbon concentration were 40 mg/l and 880 mg/l respectively. The total nitrogen (TN), NH4+-N, TOC and COD removal achieved in CW-MFC-CL were 90.0 ± 1.15%, 94.4 ± 0.75%, 64.8 ± 3.0% and up to 99.5 ± 3.4%, respectively. The TN and NH4+-N removal in CW-MFC-CL was 20.0% and 13.6% higher than normal CW. Maximum current density achieved in CW-MFC-HF was of 75 mA/m3 and in CW-MFC-VUF was 156 mA/m3. Furthermore, the study revealed that even at low microbiological biomass, an MFC integrated CW operating in closed circuit gave higher removal of NH4+-N and COD than the normal CW and open circuit CW-MFC. Microbiological analysis shows the presence of already known nitrifier and denitrifer which indicates their role in electrode dependent nitrogen removal.

AbstractOne way of improving the efficiency of solar cells is to subdivide the broad solar spectrum into smaller energy ranges and to convert each range with a cell of appropriately matched bandgap. The most common approach to implementing this idea has been to use a monolithic or mechanical stack of cells arranged in order of increasing bandgap, with the highest bandgap cell uppermost. This provides automatic filtering of incident sunlight so that each cell absorbs and converts the optimal spectral range. The potential of an earlier experimental approach based on steering light in different wavelength bands to non‐stacked cells recently has been re‐explored with good results. The present work extends this previous work by putting measurements on a more rigorous basis and by improving the ‘composite’ experimental efficiency of selected cells to beyond 43%, the highest reported to date for any combination of photovoltaic devices. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract We report fabrication of nanostructured, laser-doped selective emitter (LDSE) silicon solar cells with power conversion efficiency of 18.1% and a fill factor (FF) of 80.1%. The nanostructured solar cells were realized through a single step, mask-less, scalable reactive ion etch (RIE) texturing of the surface. The selective emitter was formed by means of laser doping using a continuous wave (CW) laser and subsequent contact formation using light-induced plating of Ni and Cu. The combination of RIE-texturing and a LDSE cell design has to our knowledge not been demonstrated previously. The resulting efficiency indicates a promising potential, especially considering that the cell reported in this work is the first proof-of-concept and that the fabricated cell is not fully optimized in terms of plating, emitter sheet resistance and surface passivation. Due to the scalable nature and simplicity of RIE-texturing as well as the LDSE process, we consider this specific combination a promising candidate for a cost-efficient process for future Si solar cells.

Abstract In this work we report the Na incorporation from Na-doped Mo (Mo-Na) back contact for kesterite Cu2ZnSnS4 solar cells on flexible stainless steel substrates. It is demonstrated that Na can be effectively incorporated into CZTS by inserting Mo-Na layer at back contact. Direct contact of CZTS and Mo-Na layer leads to poor homogeneity and adhesion. The thickness of MoS2 formed at the back contact depends on the presence of Na and whether Mo contacts with CZTS directly. Back contact configuration with a Mo capping layer on Mo-Na layer is found to be helpful to maintain the advantages of Mo back contact and control the thickness of MoS2 interface. As a result, CZTS device fabricated on this configuration yields higher conversion efficiency of 6.2%. However, this efficiency is still far lower than that on traditional soda lime glass substrate which shows efficiency over 8%. The loss mechanism of device fabricated on stainless steel is investigated and analyzed according to the device performance and electrical parameters.