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[en] A compact, low-cost and high-output-power silicon-wafer solar strip-cells-array module (SCAM) was experimentally demonstrated. The proposed SCAM consisted mainly of a silicon-wafer strip-cell sparse array and low-concentration-ratio array concentrator based on an epoxy resin polymer (ERP) cylindrical plano-convex lens. A polymer replication process based on a polydimethylsiloxane mold was used to fabricate the ERP lens array concentrator. The results show that 46.94% of the silicon-wafer cell was saved in the designed SCAM. Moreover, the output power of the SCAM with a low concentration ratio of 8 suns was improved by 8.6%, compared with a whole piece of a conventional silicon-wafer solar cell with the same area as the module. The proposed method encapsulating solar cells provides a means to reduce the usage of silicon cells in modules as well as improving the output power of modules. (paper)
[en] This paper has conducted a contrastive study on the AIRS retrieval results and the observational data of methane concentration at Mt. Waliguan atmospheric background station, and has analyzed the distribution characteristics of atmospheric methane concentration over the Qinghai-Xizang Plateau from 2003 to 2015. The results show that the AIRS retrieval data display the same monthly, annual, and seasonal variation trend, as well as segmental variation characteristics. The methane concentration features high in the north and low in the south along with the geographical line of Kunlun Mountains–Tanggula Mountains–Hengduan Mountains, and decreases significantly as the altitude rises, with the highest and the most sensitive variability in the south central region of the Qinghai-Xizang Plateau. From 2003 to 2015, the methane concentration in the Qinghai-Xizang Plateau continued to rise, with the fastest growth in autumn, the slowest in winter, and an annual growth rate of 5.2 nmol mol−1 a−1, while the growth rate from 2013 to 2015 was lower than the global average. The seasonal variation showed a unimodal curve, with the highest value in summer and the lowest value in spring, and with the altitude rising, the seasonal variation was more significant.
[en] Superabsorbent polymer (SAP) is a kind of polymer with advantages like high water absorption and conservation. We studied the effect of various concentrations of SAPs on the infiltration of soil water with sand mulching. Five soil columns with surface sand mulch and evenly distributed SAPs at concentrations of 0, 0.1, 0.2, 0.5 and 1.0% were tested. The SAPs slowed the migration of the wetting front and thus the rate of infiltration of water, and the higher the SAP concentration, the slower the migration. The relationship between the wetting front displacement and time could be described by a logarithmic function, . The amount of cumulative infiltration was inversely proportional to the amount of SAPs. The final cumulative infiltration was proportional to the amount of SAPs, within a limited range. The relationship between cumulative infiltration and time was described by a power function, . The relationship between wetting front displacement and cumulative infiltration could be characterized by a linear equation, , indicating that the rate of cumulative infiltration increased with the amount of SAPs for the same infiltration depth, which satisfied the Kostiakov model (). High concentrations of SAPs strongly inhibited the infiltration of water. The infiltration rate of soil water was optimal at a SAP concentration of 0.2%, which effectively increased the amount of water in the soil.
[en] Effects of chloride, introduced with 0.03, 0.05, 0.10, 0.12, 0.22, 0.25 M, on the corrosion behavior of API-X100 pipeline steel in 0.15 M carbonate solutions were studied. The evaluations were carried out with monitoring the open-circuit potentials and electrochemical impedance spectroscopy (EIS). The open-circuit potentials gave an electrochemical evidence on the weakening opposite kinetics of the passive film formation to the kinetics of dissolution with higher chloride concentrations. The open-circuit potentials were less with higher chloride concentrations. The EIS tests indicated that the corrosion resistance decreased, and species diffusion increased with the chloride concentration, in multi-time constant interactions. In all tests, slippery transparent films formed with no presence of pitting on the sample surfaces.
[en] Highlights: • Concentration profiles of products and reactant for the thermal oxidation of PEO were determined. • The kinetics of oxidation of PEO were estimated by model fitting to concentration profiles. • A new formation scheme of ROOH via ROO reaction with HO2 was proposed according to the kinetics data. • The auto-oxidation scheme of polymer was revised. ROOH was a key intermediate compound in oxidation of polymer because it was only source of OH radicals. ROOH was believed to be produced by ROO abstraction H-atom from polymer, which is thermodynamically unfavorable, but it may be facilitated due to the high polymer concentration. However, ROOH also could be produced by ROO reaction with HO2. For examining the formation scheme of ROOH, kinetics and mechanism for the thermal-oxidative degradation of PEO at 473 K in air was investigated by using the experimental and modeling approaches. The contribution of HO2 reaction with ROO to the formation of ROOH was estimated.
[en] An analysis is presented of the ability of balanced mechanical ventilation systems to reduce the radon concentration in residential buildings efficiently. The analysis takes into account the following parameters: radon supply rate into the building, ventilation intensity, required indoor radon concentration and energy consumption. It is shown that the applicability of ventilation systems is limited mainly by energy consumption. Ventilation systems can be considered energetically acceptable if the ventilation intensity does not exceed 0.6 h-1, i.e. radon supply rate should not exceed 60 Bq/m3h for a required indoor radon concentration of 100 Bq/m3. Energy consumption can be significantly reduced by operating the ventilation system in a cyclic mode. Simulating the behavior of ventilation systems in time has been found as a useful tool for their design. In order to express by one parameter energy consumption and radon reduction, a completely new quantity - the 'radon-related energy need' has been proposed. (authors)
[en] The influence of external forcings on surface temperature is not fully understood at decadal to multi-centennial timescales. This study uses simulation results from the Community Earth System Model (CESM) forced by total solar irradiation (TSI), greenhouse gases (GHGs) concentrations, volcanic eruptions (VOL), and land use and land covers (LULC) to investigate the possible impacts of external forcing on decadal to multi-centennial timescales over the past 2000 years. The simulated global annual mean surface temperature (GMST) variations show a good coherence with observations over the past 150 years and proxy-based reconstructions over the past 2000 years. Ensemble empirical mode decomposition (EEMD) is used to isolate the GMST variations on decadal to multi-centennial timescales. We found that the VOL forcing has a significant effect on GMST at decadal to multi-decadal timescales, but its effect weakens gradually as the timescale lengthens. The TSI forcing is a major factor of GMST on multi-decadal to sub-millennial timescales, and its effect strengthens as the timescale lengthens. The GHGs is the dominant driver of recent warming, but its effect is weak in the pre-industrial times. The LULC could lead to a slight cooling trend over the past 2000 years but has no large impact on GMST at decadal to multi-centennial timescales. This study reports a 2000-year length climate simulation and may contribute to better understanding external drivers of GMST at different timescales.
[en] Exposure assessment is an important part in environmental epidemiology for determining the associations of environmental factors with health effects. One of the greatest challenges for personal exposure assessment is associated with peoples’ mobility during the day and spatial and temporal dynamics of air pollution. In this study, the impact of PM10 (particulate matter less than 10 μm) on allergy risk among adults was assessed using objective methods of exposure assessment. The primary objective of the present study was to estimate personal exposure to PM10 based on individual daily movement patterns. Significant differences between the concentration of PM10 in different microenvironments (MEs) and personal exposure to PM10 were determined. Home exposure accounted for the largest part of PM10 exposure. Thirty-five percent of PM10 exposure was received in other non-home MEs. Allergy risk increased significantly with increasing exposure to PM10. Adults exposed to the highest levels of PM10 exposure had a twice-higher risk of allergies than adults exposed to the lowest levels of PM10 exposure. The study results have practical relevance for exposure assessment to environmental factors and its impact on health effects.
[en] 222Rn (radon) is an ever-present radioactive component of the surface layer of the atmosphere. The knowledge of the shape of radon activity concentration (RAC) time series has several important applications in atmospheric studies. This study presents the results of RAC analysis according to Garzon et al. approach during the years 1991-2009, as well as attempts to reconstruct the shape of composite diurnal RAC cycles using either Garzon et al. original approach or other methods. From this study, it follows that in order to accurately reconstruct the mean diurnal RAC cycles for individual months in our locality (Central European region), the parameters have to be calibrated by local RAC and measured global solar radiation data. The original Garzon et al. approach underestimates the amplitude of mean diurnal RAC cycles during April-August by up to 10%, and overestimates the amplitude during September-March by up to 25%. (authors)
[en] The preparation of carbons in virgin and Ti-modified forms under controlled conditions at low temperature from plantain pseudo-stem (Musa paradisiaca) was achieved. These prepared carbons were characterized for instrumental studies such as BET, FTIR, XRD, SEM with EDS and TGA to understand the chemistry and modification. The determination of IEP and pHZPC established the presence of positive surface sites on the virgin (VMPC) and Ti-modified (TiMPC) carbons to facilitate the sorption of fluoride. The fluoride removal efficiency as a function of time, pH, dose, initial fluoride concentration, temperature, and co-ion intervention was studied. The maximum fluoride removal of about 81.2 and 97.7% was achievable with VMPC and TiMPC, respectively, after 20 min at the pH of 2.04 and continued for the equilibrium of 60 min. Temperature was found to be influential both by way of initial increase followed by a decrease in the fluoride uptake of MPCs. Regeneration was very consistent up to 7 cycles with the residual fluoride concentration below the WHO guide line of 1.5 mg L−1. Highest intervention due to hydrogen carbonate ions was observed during the fluoride removal process. Kinetic (pseudo-first-order, pseudo-second-order, and intra-particle diffusion) and isotherm models (Langmuir, Freundlich, and DKR) were checked for their compliance with the present sorption system. These low temperature synthesized MPCs are found to be effective candidates in the process of fluoride abatement in water.