Search Results (243)

This study assessed the carbonation-related durability of an existing reinforced concrete building in Seoul scheduled for demolition to examine the level of durability performance commonly assumed for building structures. The compressive strength of concrete core specimens was compared with the estimated compressive strength derived from the rebound hammer, showing similar overall trends despite noticeable scatter, indicating that rebound testing can serve as a supplementary indicator when interpreted with caution. Carbonation depth measurements revealed that indoor locations tended to exhibit the greatest carbonation depths, likely reflecting higher CO₂ concentrations associated with occupancy and daily activities, as well as indoor ventilation and moisture conditions. For exterior walls, orientation affected carbonation progress; carbonation depths were greater on the southwest-facing wall than on the northwest-facing wall, suggesting that higher solar radiation may promote drying and facilitate CO₂ diffusion, thereby accelerating carbonation. When the carbonation rate coefficients were compared under similar compressive strength conditions, the southeast-facing wall exhibited a coefficient approximately 1.1 times greater than that of the northwest-facing wall. These results indicate that carbonation cannot be explained by strength alone and highlight the importance of incorporating exposure-related factors (e.g., solar radiation, drying, rainfall, and shielding) into carbonation behavior assessment. Full article

The high expansion rate of industrial-scale photovoltaic (PV) systems in emerging economies requires proper performance prediction models that consider particular climatic variabilities. Although the theoretical potential of solar energy in South Asia is well documented, there still exists a gap in the validation of simulation models to operational data over long periods in subtropical monsoon climates. Unlike prior studies, this work combines multi-year operational data with dynamic TRNSYS simulations to quantify both technical and environmental performance of a 1 MW PV system under subtropical monsoon conditions. This paper provides a detailed performance evaluation of a 1 MW grid-connected PV system located in Punjab, Pakistan. The actual performance of the system is compared with a dynamic simulation model that is created in the Transient System Simulation Tool (TRNSYS) using three years of operational data. Four different scenarios are analyzed: (1) Ideal Theoretical Operation, (2) Actual Field Data, (3) Simulated Operation with Maximum Power Point Tracking (MPPT), and (4) Simulated Operation without MPPT. The results reveal that the real system produced an average of 1342 MWh/year, whereas the MPPT-enabled simulation predicted 1664 MWh/year, indicating a performance difference of 19.3%. Statistical validation revealed a strong correlation ($R^2=0.84$) between the model and reality, yet identified a normalized Root Mean Square Error (nRMSE) of 26.8%. This deviation represents a performance gap which is deconvoluted into agricultural soiling losses and grid curtailment. The research work quantifies the technical effect of MPPT where a 27% operational advantage is realized in comparison to fixed-voltage cases, proving its necessity in climates with high diffuse radiation during monsoon seasons. Economic analysis demonstrates a Levelized Cost of Energy (LCOE) of $0.0378/kWh of the existing system, and a Simple Payback Time (SPBT) of 4.74 years at the current industrial tariffs. Sensitivity analysis also indicates that in case of an increase in grid tariffs to 50 PKR/kWh, Internal Rate of Return (IRR) increases to 18.8%. Environmental analysis confirms a carbon emission reduction of 765 tons/year. These results validate the techno-economic feasibility of large-scale PV in the area and provide an important understanding of the critical yield losses in monsoon seasons, which offers an effective robust benchmark for future industrial energy policy in developing economies. Full article

Skin pigmentation results from the melanin production by melanocytes, an essential process for protection against ultraviolet radiation and for maintaining cutaneous homeostasis. Disruptions in this balance lead to pigmentary disorders, such as hyperpigmentation, which is characterized by localized or diffuse darkening of the skin. Its most prevalent forms include melasma, post-inflammatory hyperpigmentation, and solar lentigines, often driven by hormonal, inflammatory, and environmental factors, particularly sun exposure. Despite being clinically benign, these conditions have a significant impact on self-esteem and quality of life. Conventional treatments rely on depigmenting agents such as hydroquinone, retinoids, and corticosteroids, as well as chemical peels, and laser or light-based therapies, frequently used in combination. However, limited efficacy, prolonged treatment durations, and potential adverse effects underscore the need for safer and more effective alternatives. In recent years, research has focused on developing novel approaches, with nanotechnology-based delivery systems and minimally invasive techniques, such as microneedling, standing out as particularly promising fields. In parallel, the growing number of interventional clinical trials reflects an increasing interest in optimizing topical depigmenting strategies. This review summarizes the main types of hyperpigmentation, the depigmenting substances currently used, and emerging therapeutic approaches with potential clinical impact. Full article

This study experimentally evaluated the performance of a wall confluent jet (WCJ) cooling system in a greenhouse under real summer and autumn weather conditions. It examined the effects of indoor air temperature setpoint (T_spt), number of nozzle rows (n) on the WCJ diffuser, and external wall shading on WCJ’s cooling performance. Thermocouples and constant-current anemometers measured air and surface temperatures and air velocity, while pyranometers measured solar radiation. The WCJ system dynamically regulated inlet air temperature between 14 °C and 25 °C to counter solar and conductive heat gains, maintaining indoor air temperature within ±1.5 °C of the setpoint. Increasing T_spt by 4 °C reduced inlet cooling demand by 25% but increased indoor air temperature by 20–25% and raised ceiling, wall, and floor surface temperatures by 17%, 20%, and 16%, respectively. Increasing n reduced surface temperatures by up to 8% and indoor air temperature by 6%. External wall shading reduced solar heat gain, lowering interior surface temperatures by 10–30%, peak and mean indoor air temperatures by up to 35% and 15%, and net power peaks by 40%. Autumn conditions reduced cooling loads by 50% relative to summer. Overall, WCJ cooling demonstrates strong potential as an alternative or complementary system for greenhouse thermal regulation without increasing primary energy demand. Full article

The optical properties of greenhouse cover materials play a critical role in controlling the internal light environment, directly affecting photosynthetic performance and crop productivity. This study evaluates the impact of a high photosynthetically active radiation (PAR) transmittance and high-light-diffusivity polyethylene film on the microclimate, photosynthetic activity, yield, and disease incidence of cucumber (Cucumis sativus L.) crops grown in a Mediterranean passive solar greenhouse. Trials were conducted over two consecutive autumn–winter seasons using a multi-span greenhouse divided into two sectors: one covered with an experimental high-transmittance film and the other with a standard commercial plastic. The experimental cover increased PAR transmission by 8.7% and 11.6% at canopy level in the first and second seasons, respectively, leading to improvements in leaf-level net photosynthesis of 9.3% and 17.9%. These effects contributed to yield increases of 5.0% and 17.3% in the respective seasons. The internal air temperature rose by up to 1.3 °C without exceeding critical thresholds, and no significant differences were observed in plant morphology or fruit quality between treatments. Additionally, the experimental film reduced the incidence of major fungal diseases, particularly under higher disease pressure conditions. The use of high-PAR-transmittance films enhances radiation use efficiency and crop performance in resource-limited environments without increasing energy inputs. This approach offers a sustainable, low-cost strategy to improve yield and disease resilience in protected cropping systems under passive climate control. Full article

This study introduces a multidimensional mathematical model and a robust numerical algorithm with second-order accuracy for modeling the complex coupled processes of heat and moisture transfer with gas-pressure-driven flow, based on time-fractional differential equations (with Caputo derivatives of order 0 < α ≤ 1), which capture the memory effects and anomalous diffusion inherent in heterogeneous porous media. The proposed model integrates conductive and convective heat transfer; moisture diffusion and phase change; and pressure dynamics within the pore space and their bidirectional couplings. It also incorporates environmental interactions through boundary conditions for heat and moisture exchange with the ambient air; internal heat and moisture release; transient influx of solar radiation; and material heterogeneity, where all transport coefficients are spatially variable functions. To solve this nonlinear and coupled system, we developed a high-order, stable finite-difference scheme. The numerical algorithm employs an alternating direction-implicit approach, which ensures computational efficiency while maintaining numerical stability. We demonstrate the algorithm’s capability through numerical simulations that monitor and predict the spatiotemporal evolution of coupled transport temperature, moisture content, and pressure fields. The results reveal how heterogeneity, diurnal solar radiation, and internal sources create localized hot spots, moisture accumulation zones, and pressure gradients that significantly influence the overall dynamics of storage and drying processes. Full article

The accurate short-term forecasting of global horizontal irradiance (GHI) is essential to optimizing the operation and integration of solar energy systems into the power grid. This study evaluates the performance of the Weather Research and Forecasting (WRF) model in predicting GHI over a 48 h forecast horizon at an Italian site: the ENEA Casaccia Research Center, near Rome (central Italy). The instantaneous GHI provided by WRF at model output frequency was post-processed to derive the mean GHI over the preceding hour, consistent with typical energy forecasting requirements. Furthermore, a decomposition model was applied to estimate direct normal irradiance (DNI) and diffuse horizontal irradiance (DHI) from the forecasted GHI. These derived components enable the estimation of solar energy yield for both concentrating solar power (CSP) and photovoltaic (PV) technologies (on tilted surfaces) by accounting for direct, diffuse, and reflected components of solar radiation. Model performance was evaluated against ground-based pyranometer and pyrheliometer measurements by using standard statistical indicators, including RMSE, MBE, and correlation coefficient (r). Results demonstrate that WRF-based forecasts, combined with suitable post-processing and decomposition techniques, can provide reliable 48 h predictions of GHI and DNI at the study site, highlighting the potential of the WRF framework for operational solar energy forecasting in the Mediterranean region. Full article

This article presents a database focused on measuring the experimental performance of a pilot parabolic trough collector (PTC) combined with the meteorological conditions corresponding to the installation site. Water was chosen as the fluid to recirculate through the PTC circuit. The data were recorded between August and September, assuming that global radiation was adequate for use in the concentration process. The database comprises seven experimental tests, which contain variables such as time, inlet temperature, outlet temperature, ambient temperature, global radiation, diffuse radiation, wind direction, wind speed, and volumetric flow rate. Based on the data obtained from this pilot PTC system, it is possible to provide relevant information for the installation and construction of large-scale solar collectors. Furthermore, the climatic conditions considered allow key factors in the design of multiple collectors to be determined, such as the type of arrangement (series or parallel) and manufacturing materials. In addition, the data collected in this study are key to validating future theoretical models of the PTC. Finally, considering the real operating conditions of a PTC in conjunction with meteorological variables could also be useful for predicting the system’s thermal performance using artificial intelligence-based models. Full article

This study is devoted to investigating the effect of aerosols on solar UV radiation. In the ultraviolet range, scattering processes are dominant and lead to a substantial contribution of diffuse UV radiation to the global UV irradiance. The paper introduces a method for estimating solar UV Index. The proposed method is first compared with other UV Index estimation methods and is subsequently applied to examine the influence of aerosols and ozone on solar UV radiation and on its diffuse component. Human skin exposure to diffuse solar UV radiation can be potentially harmful to health. Full article

This paper reports a novel effort to estimate and evaluate the coefficients of Hg transfer across the water/air interface in lakes such as Cane Creek Lake (CCL, Cookeville, TN, USA). This was accomplished by calculating the coefficients (k_w) using the Two-Thin Film (TTF) Model for Hg transfer together with the field-measured data of Hg emission flux (F), dissolved gaseous mercury concentration (DGM), air Hg concentration (C_a), and water temperature for Henry’s coefficient (K_H) obtained from a separate field study at the CCL. The daily mean k_w values range from 0.045 to 0.21 m h⁻¹, with the min. at 0.0025–0.14 and the max. at 0.079–0.41 m h⁻¹, generally higher for the summer, and from 0.0092 to 0.15, with the min. at 0.0032–0.033 and the max. at 0.017–0.31 m h⁻¹, generally lower for the fall and winter, exhibiting an apparent seasonal trend. The highest k_w values occur in August (mean: 0.21, max.: 0.41 m h⁻¹). Our k_w results add to and enrich the aquatic interfacial Hg transfer coefficient database and provide an alternative avenue to evaluate and select the coefficients for the TTF Model’s application. The k_w results are of value in gaining insights into the Hg transfer actually occurring across the water/air interface under environmental influences (e.g., wind/wave, solar radiation). Our k_w results do not show a clear, consistent correlation of k_w with wind/wave effect, nor sunlight effect, in spite of some correlations in sporadic cases. Generally, the k_w values do not exbibit the trends prescribed by the model sensitivity study. The comparisons of our k_w results with those obtained using wind-based transfer models (the Liss/Merlivat Model, the Wanninkhof Model, and the modified linear model) show that they depart from each other. The findings of this study indicate that the TTF Model has limitations and weaknesses. One major assumption of the TTF Model is the equilibrium of the Hg distribution between the air and water films across the water/air interface. The predominant oversaturation of DGM shown by our DGM data evidently challenges this assumption. This study suggests that aquatic interfacial Hg transfer is considerably more complicated, involving a group of factors, more than just wind and wave. Full article

To validate a positive relationship between air temperature (T) and atmospheric substances (S/G, a ratio of diffuse solar radiation to global solar radiation) found at four typical stations on the Earth, and a further investigation was conducted. Based on the analysis of long-term solar radiation, atmospheric substances, and air temperature at 29 representative stations of baseline surface radiation network (BSRN) in the world, the relationships and the mechanisms between air temperature and atmospheric substances were studied in more detail. A universal non-linear relationship between T and S/G was still found, which supported the previous relationship between T and S/G. This further revealed that a high (or low) air temperature is strongly associated with large (or small) amounts of atmospheric substances. The mechanism is that all kinds of atmospheric substances can keep and accumulate solar energy in the atmosphere and then heat the atmosphere, causing atmospheric warming at the regional and global scales. Therefore, it is suggested to reduce the direct emissions of all kinds of atmospheric substances (in terms gases, liquids and particles, and GLPs) from the natural and anthropogenic sources, and secondary formations produced from atmospheric compositions via chemical and photochemical reactions (CPRs) in the atmosphere, to slow down the regional and global warming through our collective efforts, by all mankind and all nations. Air temperature increased at most BSRN stations and many sites in China, and decreased at a small number of BSRN stations during long time scales, revealing that the mechanisms of air temperature change were very complex and varied with region, atmospheric substances, and the interactions between solar radiation, GLPs, and the land. Full article

Atmospheric formaldehyde (HCHO) is a major component of oxygenated volatile organic compounds (OVOCs) and plays an important role in O₃ formation and atmospheric oxidation capacity. In this study, seasonal observations of gaseous pollutants (HCHO, O₃, peroxyacetyl nitrate (PAN), CO, NOx, and VOCs) and ambient conditions (J_HCHO, J_NO2, solar radiation, temperature, relative humidity, wind speed, and wind direction) were conducted in a coastal city in southeast China. The average HCHO concentrations were 2.54 ppbv, 3.38 ppbv, 2.53 ppbv, and 1.98 ppbv in spring, summer, autumn, and winter, respectively. Diurnal variations were high in the daytime and low in the nighttime, and the peak times varied in different seasons. The correlation between HCHO and O₃ was not significant in spring and winter, which is likely related to the effects of photochemical reactions and diffusion conditions. The contributions of background (23.0%), primary (47.6%), and secondary (29.4%) sources to HCHO were quantified using multiple linear regression (MLR) models, revealing that secondary formation was the most significant contributor in summer, whereas primary emissions were predominant in spring. These findings help to improve the understanding of the influence of atmospheric formaldehyde on photochemical pollution control in coastal cities. Full article

Rapid urbanization across Southern Asia’s coastal regions has significantly increased electricity demand, driving India’s solar sector expansion under the National Solar Mission and positioning the country as the world’s fourth-largest solar market. Nonetheless, methodological limitations remain in applying GIS-based multi-criteria decision analysis (MCDA) frameworks to coastal urban microclimates, which involve intricate land-use dynamics and resilience constraints. To address this gap, this study proposes a multi-criteria GIS- based Analytical Hierarchy Process (AHP) framework, incorporating remote sensing and geospatial data, to assess Solar Farm Sites (SFSs) suitability, supplemented by sensitivity analysis in Thoothukudi coastal city, India. Ten parameters—covering photovoltaic, climatic, topographic, environmental, and accessibility factors—were used, with Global Horizontal Irradiance (18%), temperature (11%), and slope (11%) identified as key drivers. Results show that 9.99% (13.61 km²) of the area has excellent suitability, mainly in the southwest, while 28.15% (38.33 km²) exhibits very high potential along the southeast coast. Additional classifications include good (22.29%), moderate (32.41%), and low (7.16%) suitability zones. Sensitivity analysis confirmed photovoltaic variables as dominant, with GHI (0.25) and diffuse radiation (0.23) showing the highest impact. The largest excellent zone could support approximately 390 MW, with excellent and very high zones combined offering up to 2080 MW capacity. The findings also underscore opportunities for dual-use solar deployment, particularly on salt pans (17.1%), as well as elevated solar installations in flood-prone areas. Overall, the proposed framework provides robust, spatially explicit insights to support sustainable energy planning and climate-resilient infrastructure development in coastal urban settings. Full article

Solar photovoltaic (PV) plays a crucial role in China’s pursuit of carbon neutrality. Assessing the PV power potential over China is essential for future energy planning and policy making. Surface solar radiation and panel tilt angle are critical factors influencing PV power generation. However, existing solar radiation datasets cannot fully meet assessment needs due to insufficient temporal coverage and limited accuracy, and the impact of panel tilt angles on PV potential is largely overlooked. This study developed a PV power estimation framework to assess the long-term (1980–2019) PV power potential at 609 stations across China, based on reconstructed high-quality solar radiation and optimized tilt angles. The validation of PV power estimates using ground measured outputs from four operational PV power stations indicated a correlation coefficient of 0.67 and a root mean square error of 0.07 for estimated daily capacity factor (CF). The assessment results revealed that the multi-year mean CF of China is 0.149 ± 0.031, with higher potentials in northern provinces and lower in southern provinces. The mean annual CF shows a declining trend of −7 × 10⁻⁴ per decade during 1980–2019, with significant decreases primarily in heavily polluted regions. In addition, we propose an optimal tilt angle estimation model based on diffuse fraction, achieving higher accuracy than previously released models. The estimated optimal tilt angle results in an increase in PV energy yield by 14.9 TWh/year for China compared with latitude-based schemes, based on China’s cumulative PV capacity by 2023 (609 GW). Our findings provide valuable insights for the effective implementation of solar PV projects in China. Full article

Urban environments encounter urgent challenges in transitioning to net-zero emissions, particularly with respect to the adoption and large-scale incorporation of renewable energy solutions such as photovoltaic (PV) technologies. This study explores the interrelation of digitized energy systems, digital twins, and open-access platforms in accelerating effective PV deployment in cities moving toward carbon neutrality. We examine how digital tools can enhance PV performance, demand-side management, and grid integration, while open-access platforms contribute to data sharing, raising awareness, public engagement, and stakeholder collaboration. We also present BIPV-city—a novel, open-access, digital, and climate-aware platform developed to support and optimize PV integration in building and urban areas. Validations of the solar irradiance calculations against PVGIS for several European cities exhibit a strong agreement, with a root mean square error (RMSE) extending from 3.3 to 7.6. The validation of the standardized BESTEST Case 600 against TRNSYS simulations for three representative climates—Athens, Prague, and Dubai—with tilt variations confirmed substantial alignment for plane-of-array (POA) radiation (within ±2% and ±6% for the global and direct/diffuse components, respectively) and annual PV yield estimations (within ±10%). The findings highlight that the BIPV-city platform is a reliable, user-friendly tool that can harness climate-responsible and scalable BIPV deployment in the built environment through digital innovation. Full article