Temperature Radiation Research Articles

Nonlinear Control of Photovoltaic (PV) Solar-Powered Centrifugal Pump for Irrigation System: A Case Study of Fadak Farm in Karbala

Abstract In both the agricultural and industrial sectors, pumping water is essential. Due to its arid climate, our Saharan area has a substantial solar energy resource, making constructing a PV solar irrigation system possible. Given solar resources' unpredictable and intermittent nature, it is imperative to set up a system that permits optimal usage. This study aims to design and simulate a solar pumping system's effective nonlinear direct torque command. A solar generator provides an asynchronous three-phase machine coupled to a centrifugal pump as part of the system. MPPT monitors the boost converter via duty cycle. The solar generator's functioning at full power will be ensured. The first uses PSO in the MPPT system to supply the motor pump with three phases of power. The second one employs direct torque command (DTC) to regulate the operation of a centrifugal pump coupled with an induction machine. More advancements will be made to the DTC scenario. The proposed mathematical model of the solar irrigation system was simulated using a MATLAB simulation environment, adopting accurate data provided by Fadak Farm. The maximum power extracted from PV tends to peak at 280 Wp with the assistance of particle swarm optimization that energizes the use of the centrifugal pump for the proposed irrigation system. It is evident from numerical simulation results based on accurate input data that the power extracted from PV solar is positively affected by solar radiation and surface temperature variations. It is clear from simulation results that the speed of three–phase I.M motor converges to 22.5 rad/sec, and water flow pumping by centrifugal is decreased and increased, converging to 7.5 *10-8 m/s with the variation of solar irradiance.

Infrared temperature distribution characteristics and state assessment method of sandstone under tension and compression stress

Abnormalities in infrared radiation temperature (IRT) often accompany the loading In this investigation, stress experiments and splitting tests were conducted on sandstone to investigate the IRT characteristics of sandstone under various loading conditions. The results shows that the Maximum Infrared Radiation Temperature (MAXIRT) increases by up to 5 °C, while in splitting tests, the minimum infrared radiation temperature (MINIRT) decreases by approximately 1.5 °C. Compared to the average infrared radiation temperature (AIRT), MAXIRT is more sensitive to compressive stress, whereas (MINIRT) is more responsive to tensile stress. The correlation between IRT indicators and stress were further analyzed. The findings reveal a positive correlation between IRT and compressive stress. At low stress levels, the correlation coefficient fluctuates between −0.4 and 0.6, generally showing low correlation. As stress increases, the correlation coefficient rises, reaching above 0.8, indicating a high correlation. Tensile stress exhibits a negative correlation, with a consistent trend. Additionally, a statistical analysis of the frequency distribution of IRT under different stress conditions was conducted, followed by hypothesis testing. The results demonstrate that the probability distribution of IRT during loading follows a skewed normal distribution. The changes in skewness can be divided into three stages: initial fluctuation, stable variation, and abrupt failure. Under compressive stress, a right-skewed distribution is observed, with skewness exceeding 3.5 before fracture and reaching above 10 near fracture. Under tensile stress, a left-skewed distribution is noted, with skewness reaching −4.5 near fracture. These findings contribute to the assessment of rock stress states and provide early warning information for predicting rock failure.

Levels of Effectiveness of Water Curtain Equipment Applied When Mitigating Fire Compartment Installation of Logistics Facilities

Mock-up tests and fire simulations were performed to verify the effectiveness of water curtain equipment in mitigating fire compartment installation of logistics facilities. The radiant-heat-blocking effect of the water curtain equipment differed significantly based on the type of drencher head, and a blocking effect was observed. Additionally, the radiant temperature and heat flux were significantly reduced when the installation intervals of the drencher heads of the water curtain equipment were reduced. Therefore, improving the standards related to the water curtain equipment of logistics facilities, e.g., providing drencher head specifications, restricting the sizes of the openings, and narrowing the installation intervals of the drencher heads, is necessary to ensure the fire safety of water curtain equipment.

Variations of Lake Ice Phenology Derived from MODIS LST Products and the Influencing Factors in Northeast China

Lake ice phenology serves as a sensitive indicator of climate change in the lake-rich Northeast China. In this study, the freeze-up date (FUD), break-up date (BUD), and ice cover duration (ICD) of 31 lakes were extracted from a time series of the land water surface temperature (LWST) derived from the combined MOD11A1 and MYD11A1 products for the hydrological years 2001 to 2021. Our analysis showed a high correlation between the ice phenology measures derived by our study and those provided by hydrological records (R2 of 0.89) and public datasets (R2 > 0.7). There was a notable coherence in lake ice phenology in Northeast China, with a trend in later freeze-up (0.21 days/year) and earlier break-up (0.19 days/year) dates, resulting in shorter ice cover duration (0.50 days/year). The lake ice phenology of freshwater lakes exhibited a faster rate of change compared to saltwater lakes during the period from HY2001 to HY2020. We used redundancy analysis and correlation analysis to study the relationships between the LWST and lake ice phenology with various influencing factors, including lake properties, local climate factors, and atmospheric circulation. Solar radiation, latitude, and air temperature were found to be the primary factors. The FUD was more closely related to lake characteristics, while the BUD was linked to local climate factors. The large-scale oscillations were found to influence the changes in lake ice phenology via the coupled influence of air temperature and precipitation. The Antarctic Oscillation and North Atlantic Oscillation correlate more with LWST in winter, and the Arctic Oscillation correlates more with the ICD.

An integrated CFD and machine learning analysis on pilots in-flight thermal comfort and productivity

In the cockpit, minimising the pilots' thermal discomfort due to solar exposure while ensuring clear visibility is essential. This study numerically examined the solar radiation effect on thermal fields of an Airbus A320 cockpit and assessed global and local thermal comfort of three aircrews using the Fanger model and the Equivalent Homogeneous Temperature (EHT) model. The productivity of aircrews based on thermal comfort was further estimated. A total of 27 cases, encompassing a combination of environmental and HVAC parameters were performed. This dataset was used for data analysis, employing an explainable machine, XGBoost, to highlight the significance of each variable on the pilot's thermal satisfaction. Outcomes proved that solar radiation penetrating the cockpit domain facilitated a non-homogeneous temperature distribution and thermal stratification. With strong solar exposure, it was recommended to set cockpit's maximum supply temperature smaller than 19 ∘ C, maintaining RH between 10–20% for appropriate global thermal environment. Aircrew productivity loss was estimated to decline by 2.7% to 5.6% due to solar intensity variation, with pilot being the most affected. Without solar radiation, the local comfort of lower body segments was compromised. Rising solar radiation resulted in significant EHT gradient changes in the upper torso compared to the lower body, highlighting the predominance of radiative heat transfer at the upper level. Analysis via XGBoost revealed that mean radiant temperature had the most substantial impact on thermal satisfaction in the cockpit, underscoring the efficiency of optimising cockpit materials for better absorption and reflection of radiative heat for enhanced thermal environment control.

Simulation of Hybrid PV Solar System with Fuel Cell in MATLAB Simulink

This paper discusses the simulation of a fuel cell hybrid solar photovoltaic system in MATLAB Simulink. To achieve the stated objective, it is proposed to dynamically model a hybrid system using Simulink to analyze its performance and optimize its operation, improving the efficiency and stability of the power supply under different operating conditions, then the dynamic simulation model employs energy conversion equations of the solar PV panel and the fuel cell to meet the electrical load requirements, where the solar panel uses solar radiation and ambient temperature, while the fuel cell produces electricity by electrolysis of water, which separates hydrogen from oxygen. In the first graph, the power at load increases sharply at 0.5 seconds and stabilizes between 0.5 and 1.5 seconds, with a sharp drop at 1.6 seconds. In the second graph, PV power increases at 0.5 seconds, reaching 80 kW between 0.5 and 1.5 seconds, dropping to zero at 1.6 seconds. The fuel cell shows similar behavior. These results indicate a coordinated operation for a stable power supply to the load, responding efficiently to changes in demand and generation.

Analysis of the three possible event horizons of anti-de Sitter space–time in the Klein–Gordon equation

In this paper, we calculate exactly the solution of Klein–Gordon equation in anti-de Sitter space–time. Due to spherical symmetry, the angular wave functions are given by spherical harmonics. The radial wave functions are given by local Heun functions. We analyze the behavior of the radial wave function in regions near three possible event horizon positions [Formula: see text] and investigate the decay rate, Hawking radiation and Hawking temperature for these three cases. Comparing the results, we verify that if the decay rate and Hawking radiation are greater, then the closer the event horizon is to the singularity of the black hole. Finally, we analyze the special case of a small black hole limit.

Optimization of sowing dates for enhanced rice yield: insights from field experiments in the middle and lower reaches of the Yangtze River, China

An efficacious strategy to adapt to climate change involves optimizing the planting season, a technique that has been extensively utilized to enhance the use of solar radiation and temperature resources in rice cultivation. Field experiments were executed in the middle and lower reaches of the Yangtze River, China, employing three distinct rice cultivars and seven disparate sowing periods spanning 2019 to 2021. The objective of assessing the impact of sowing date on apparent radiation use efficiency (RUEA), accumulated temperature use efficiencies (TUE), and overall rice yield. Subsequent to the delay of sowing dates, the duration of the comprehensive growth period initially exhibited a declining trajectory before subsequently escalating, with the reduction predominantly ascribed to a decrease in the number of days preceding heading. Furthermore, there was a tendency for both the mean daily and effective cumulative solar radiation to decline over the course of the growing period. The yield of the three rice varieties demonstrated an initial surge, which was then followed by a subsequent decline in reaction to the delay of sowing dates. A correlation analysis disclosed that solar radiation and effective cumulative temperature (EAT) were the predominant elements impacting grain yield. The outcomes of the path analysis indicate that EAT exerts the most substantial influence on yield, succeeded by cumulative total solar radiation (TSR), while photothermal quotient (PTQ) demonstrates the least impact on yield. There was a significant positive correlation between EAT and cumulative TSR with spikelets per panicle (0.237** and 0.218**), grain filling (0.753** and 0.576**), and grain weight (0.339** and 0.359**), respectively. The findings of this study indicate that an increase in yield is facilitated when the EAT after heading exceeds 594.9 ℃, the EAT surpasses 2016.7 ℃, the cumulative TSR before heading is above 1548.7 MJ m− 2, the cumulative TSR after heading is over 603.0 MJ m− 2, and the cumulative total radiation throughout the entire growth period is more than 2151.8 MJ m− 2. Furthermore, the most optimal sowing date, as identified by this study, is June 6. This study provides key insights into boosting rice productivity in the middle and lower reaches of the Yangtze River, China by analyzing the impact of temperature and solar radiation on yield and identifying optimal growth conditions.Clinical trial number Not applicable.

MoS2/N-doped hollow carbon foam for thermal insulation and broadband electromagnetic wave absorption

In this study, we demonstrated the synthesis of MoS2/N-doped hollow carbon foam (MoS2/NCF) for high performance of electromagnetic wave absorption (EMA), through high-temperature pyrolysis melamine foam and hydrothermal reaction. By adjusting the electromagnetic parameters of N-doped hollow carbon foam (NCF) through MoS2 nanosheets, the effective absorption bandwidth of MoS2/NCF reached 9.62 GHz at the matching thickness was 2.3 mm. Radar cross section (RCS) simulation results demonstrated that MoS2/NCF exhibited a strong reduction ability of RCS. At room temperature, the composite MoS2/NCF could block radiation temperature of around 110 ℃ in the case of a thickness of only 7 mm and a heating plate at 200 ℃. Moreover MoS2/NCF exhibited thermal stability and a certain flame retardants ability. The result indicated that the composite MoS2/NCF was beneficial for its application in the fields of thermal insulation and electromagnetic wave absorption.

Research on the Green Construction Technology of Stilt Houses Based on the Climate Adaptation of Transitional Seasons

Stilt houses are extremely adaptable to terrain and climate. However, current indoor thermal environment research in transitional seasons is not prominent. Therefore, in this research, a typical stilt house in southwest China was chosen as the research object and analyzed by combining Climate Consultant climate analysis software and field measurement data. The results showed that the indoor thermal stability of a stilt house was excellent during the transition season, and the attic had the most obvious climate regulation, with the maximum temperature difference between indoors and outdoors being 9 °C when the outdoor temperature was the highest. The difference between the mean radiant temperature and the average air temperature was only 0.04 °C, and the radiant effect of the enclosure on the interior was small. The indoor relative humidity ranged from 63.2% to 85.1%, showing high relative humidity, but the fluctuation was relatively stable. Stilt floors did not play a significant role in climate regulation during the transition season, and the semi-open space structure was more prone to moisture accumulation when the outdoor humidity was high. Regarding practical application, the climate adaptation strategies of shading, cooling, and dehumidification were applied in the transition season, but dehumidification was ineffective.

Study on the characteristics of acoustic-thermal precursors of destabilization damage in coal-rock combination bodies with different proportions

The instability and failure processes of coal-rock combinations are accompanied by the release of acoustic emission (AE) and infrared radiation (IR) signals. To investigate the characteristics of AE and IR signals during the failure process in coal-rock combinations with different ratios, and to analyze the effectiveness and applicability of the monitoring methods for these two signals in various specimen ratios. In this paper, the uniaxial compression tests were conducted on seven coal-rock combinations with different ratios by using the rock mechanics loading system and the cooperative monitoring platform of infrared and acoustic emission. The results show that (1) the AE counts for failure precursors in coal-rock combinations are positively correlated with the coal-rock ratio, whereas the AE peak counts are negatively correlated. Moreover, as the coal-rock ratio decreases, the slope of the cumulative AE count curve during the peak failure stage approaches 1. (2) During the elastic and yield stages, the maximum infrared radiation temperature (MIRT) curve fluctuates, and just before peak failure, the curve displays a distinctive “V” shape. This “V” shape becomes more pronounced as the coal-rock ratio decreases. (3) In the monitoring of damage precursors of coal-rock combinations, when the ratio of coal to rock is 1:3 or less, IR monitoring is better than AE monitoring. Conversely, when the ratio of coal to rock is greater than 1:3, AE monitoring is more suitable. Consequently, the combined monitoring of AE and IR signals can increase the reliability and precision of early warning signals for coal-rock assemblage damage precursors.

Carbon dioxide and evapotranspiration fluxes in an urban area of Krakow, Poland

AbstractUrban areas play an essential role in the global carbon balance, being responsible for more than 70% of anthropogenic carbon emissions, entering the atmosphere mainly in the form of carbon dioxide (CO2). Another crucial component of the carbon balance of the urban atmosphere is CO2 exchange with the biosphere, expressed in both emission and absorption fluxes. The biosphere component of the net CO2 flux is inseparably linked to the water (H2O) balance due to evapotranspiration. This article presents an estimation of CO2 and H2O net fluxes based on eddy covariance (EC) tower measurements and in‐depth analysis of its temporal and spatial variability for a typical urban site at mid‐latitude of the northern hemisphere. The source area was divided into two sectors, one representing dense urban development with sources of CO2 from traffic and households, and the second containing predominantly recreation and sports areas. Temporal variability analysis of evapotranspiration showed a clear seasonal cycle closely correlated with incoming radiation and air temperature, with the seasonal mean ranging from 0.4 mm·day−1 in winter to 1.6 mm·day−1 in summer. As a result of similar green coverage between the urban and green sectors, spatial variability was statistically insignificant. The net CO2 flux over a seasonal cycle was less pronounced for the total source area with a mean of 5.0 g C·m−2·day−1 in summer and 7.5 g C·m−2·day−1 in winter. However, significant variations between urban and green sectors were observed with the highest seasonal mean difference of 4.5 g C·m−2·day−1 in winter. The results confirm that while on the local, short time‐scale urban vegetation has a potential to mitigate the emissions, it is not able to offset them.

Real-Time Indoor Environmental Quality (IEQ) Monitoring Using an IoT-Based Wireless Sensing Network

In recent years, our time spent indoors has risen to around 90% and to maintain an occupant’s comfort and well-being, Indoor Environmental Quality (IEQ) is monitored. Concerned with inhabitant’s satisfaction and health, the adoption of smart solutions for IEQ monitoring and improvement has expanded. The solution this study explores is an occupant-centric approach involving the implementation of an Internet of Things (IoT) IEQ sensing network in a prominent office skyscraper in Hong Kong. Over the course of 15 months, real-time IEQ data were collected from 12 locations within the building. The data were collected at 1-min time intervals and consisted of readings of indoor air temperature, radiant temperature, relative humidity, air velocity, carbon dioxide (CO2), particulate matter (PM10 and PM2.5), horizontal illuminance levels, and sound pressure levels, which served as the basis of the assessment made about the qualities of thermal comfort, indoor air quality (IAQ), aural comfort, and visual comfort. Compared to traditional periodic surveys, this IoT-based sensing network captured instantaneous environmental variations, providing valuable insights into the indoor environment’s spatial characterization and temporal dynamics. This smart solution also assisted facility management in terms of identifying sources of discomfort and developing effective mitigation strategies accordingly. This study presents an occupant-centric approach to improve occupant comfort and energy efficiency within office buildings. By customizing the built environment to enhance occupants’ well-being, comfort, and productivity, an emphasis is placed on a more personalized and occupant-focused design strategy. This approach integrates technical design with human experience, highlighting the importance of real-time physical and subjective surveys for achieving optimal results.

Quantifying the potential of evidence-based planting-pattern for reducing the outdoor thermal stress from a bio-meteorological perspective in tropical conditions of Indian cities.

The impact of declined natural greenery and increased built surfaces exacerbates heat stress in urban areas causing limited usage of outdoor spaces. Greenery strategies such as trees are capable of mitigating outdoor thermal stress gain because of their phytological properties. While urban greenery guidelines have suggested the ad-hoc procedure of tree planting-schemes based on aesthetic-value, soil-water preservation etc., understanding of their morphological character help in regulating extreme thermal condition. Hence, this study aims to investigate the most efficient planting pattern based on canopies densities and trees clusters for reducing the outdoor thermal stress from bio-meteorological perspective.It initiates with the measurement of the site's morphological and meteorological attributes in existing commercial market of Bhopal City which has a humid sub-tropical climate (Aw, Koppen climate categorization). Furthermore, it leads to the development of 4-different iterated clusters incorporating moderate to high-density canopies and their overlaps pattern to estimate reduction potential in outdoors using field surveys and validated simulation model. The reduction potential in terms of magnitude and duration of thermal stress is quantified across 3-thermal variables i.e., air temperature, mean radiant temperature and universal thermal climate index. Results indicate highly-dense canopies are more effective in reducing greater magnitude of thermal stress along longer duration. Also overlapped planting pattern within the same canopy density does not make significant difference in stress reduction as compared to the changing the densities. This study will help planners and landscape architects to adopt evidence-based planting-pattern strategies for improving outdoor microclimate.

Field evaluation of the efficacy of passive radiative cooling infrastructure: A case study in Phoenix Arizona

Radiative properties of shade structures affect their surface temperatures, sensible heat fluxes and longwave and shortwave radiation exchange. In fact, structures with high solar reflectance and thermal emittance have the potential to remain below ambient air temperatures, convecting sensible heat from the air to the surface and then radiating that heat to space—a sort of radiant heat pump.We explore cooling benefits of urban surfaces with high solar reflectance and high thermal emittance radiative cooling films through a field measurement campaign in Phoenix Arizona, USA. The tested films have solar reflectance and selective thermal emittance (in wavelengths 8–13 μm) close to 95 %. We applied films in both before-after and control-test experimental designs on thin metal roofs of park shade structures. We measured surface temperatures, surface heat fluxes, upward- and downward-welling longwave and shortwave radiation, and local weather conditions.Results demonstrate the ability of radiant cooling films to reduce surface temperatures on hot days below ambient air temperatures. Test surfaces with cooling films were an average of 7 °C cooler than control shelter surfaces over the diurnal cycle, reducing sensible heat fluxes into the environment by up to 80 %, and lowering mean radiant temperatures for pedestrians using the shelters by more than 3 °C. It was also observed that the sum of the net reflected shortwave and emitted longwave radiation over the diurnal cycle can exceed the total incident longwave and shortwave radiation on the surface, demonstrating the ability of these materials to radiatively “pump” heat out of the city.

Changes in Water Surplus or Deficit and Possible Drivers in the North China Plain During 1961–2022

ABSTRACTIn the North China Plain (NCP), the assessment of water surplus or deficit (WSD), which is calculated as precipitation minus reference evapotranspiration (ET0), holds significant implications for water resource management and agricultural irrigation decision‐making, given the region's long‐standing severe shortage of water resources. However, the magnitude, trend and climatic drivers of WSD remain poorly understood in the NCP. This study analysed the spatial and temporal characteristics of WSD, and quantified the contribution of climatic factors to WSD based on the sensitivity and contribution rate analysis methods with climatic data from 75 meteorological stations. The result showed that: (1) Annual WSD decreased mainly in northeastern NCP and increased significantly in southern NCP during 1961–2022. Annual WSD increased slightly from 1961 to 2022 at a rate of 1.63 mm a−2 mainly due to the more significant decrease (−1.88 mm a−2) in ET0 compared to precipitation (−0.25 mm a−2). (2) In terms of the sensitivity of WSD to climatic factors, relative humidity had the highest sensitivity, followed by net radiation, wind speed, precipitation and average air temperature. (3) Significant declines of wind speed were the most dominant factor affecting WSD variation in most part of NCP during most of a year, and net radiation of four stations in the western high‐elevation regions played the most important role. This study enhances comprehension of the impact of climate change on WSD in the NCP and provides a reference for improving management of agricultural water resources under NCP's evolving climatic conditions.

Influence of view factors on outdoor thermal comfort of residential areas in hot-humid regions.

Sky View Factor (SVF) is commonly used to describe the impact of urban geometry on the urban thermal environment. Shading effects from plants and buildings also exert a considerable influence. To investigate the influence of view factors on outdoor thermal comfort in residential areas, we employed the Physiological Equivalent Temperature (PET) and view factors (SVF, TVF, BVF) as indicators to determine outdoor thermal comfort and the quantity of shaded spaces. Thermal measurements collected from 13 points in Guangzhou, China, Our findings revealed that high TVF points exhibited more stable air temperature throughout the daytime, with average temperature differentials ranging 0.4-1.9°C lower than other points. Air temperature demonstrated a positive correlation with SVF (R2 = 0.53), while exhibiting a negative correlation with TVF (R2 = 0.45). Additionally, shading provided by plants and buildings manifests heterogeneity. At similar SVF levels, points predominantly shaded by plants (TVF > BVF) showcased lower Mean Radiant Temperature (MRT) and PET compared to points shaded mainly by buildings (BVF > TVF). The maximum reduction in air temperature and PET reached 1.1°C and 1.2°C, respectively. BVF exerted greater influence earlier in the morning, as solar altitude angle rises, the average thermal parameters of sites with BVF > TVF escalated rapidly until eventually surpassing sites with TVF > BVF. Last, superior thermal conditions were only ensured under high shading conditions. When the effective shading ratio of plants and buildings diminished (SVF > 0.3), the microclimate of measurement points might be impacted by the long-wave radiation from the underlying surface.

Proposal of Three Methods for Deriving Representative Mean Radiant Temperatures Considering Zone Spatial Distributions

Mean radiant temperature (MRT), which is a crucial factor for thermal comfort, varies within a space. This renders deriving the representative values for radiant heating and cooling control challenging. This study reviewed existing methods for deriving MRT in previous research and addressed their limitations by proposing a method for determining a representative MRT value. The existing methods were categorized as air temperature, single location, and area weighted. Three methods for deriving representative MRT values were proposed, considering the building’s usage, scale, and applicable system installations. The proposed methods were categorized as single-zone averaged, multi-zone averaged, and point-zone MRT. Experiments were conducted by distinguishing cases based on the control of equipment systems during heating and cooling periods. During the cooling season, the single-zone averaged MRT and air temperature differed by up to 4 °C, and the difference between the multi-zone averaged MRT and MRT at a point in the perimeter zone reached up to 7 °C. During the heating season, the single-zone averaged MRT and air temperature differed by up to 2.2 °C. Thus, the results of this study emphasize the importance of applying different methods of deriving representative MRT values depending on the size and usage of the building, and demonstrate that this facilitated more effective heating and cooling control systems.

Evaluating the cooling performance of vegetation combined with a fountain in horizontal and vertical urban environments

Urban greenery and fountains effectively mitigate the urban heat island (UHI) effect. While many studies have assessed individual vegetation configurations (grass, shrub, and tree) and fountains at pedestrian heights, few have explored their combined effects horizontally and vertically. This study uses the ENVI-met model to evaluate the cooling effects of three vegetation configurations and their combinations with fountains in a typical historical and cultural neighborhood. The “grass, shrub, tree and fountain” scenario achieved the most substantial cooling, reducing air temperature (Ta) by 5.61 °C and mean radiant temperature (Tmrt) by 17.39 °C. Adding shrubs to the existing trees had minimal impact on Ta and Tmrt. Incorporating fountains into various vegetation configurations scenarios further lowered Ta by 3.58°C-3.66 °C and Tmrt by 2.97°C-3.27 °C. Trees primarily improved Tmrt through shading, while fountains were more effective at reduce Ta. This study offers theoretical and scientific guidance for optimizing urban street microclimate design from horizontal and vertical perspectives.

A Holistic View of Asphalt Binder Aging under Ultraviolet Conditions: Chemical, Structural, and Rheological Characterization

Asphalt, as a key binder material in road construction, is susceptible to ultraviolet (UV) radiation-induced aging, leading to embrittlement and reduced durability. Despite the significance of UV aging, research in this area remains limited compared to that on thermal aging. This paper comprehensively reviews the current state of research on UV aging in asphalt, focusing on its mechanism, evaluation indicators, and methods to delay or avoid UV aging. The structural components, rheological properties, and aging mechanisms of asphalt are discussed. Various UV aging simulation methods, including the use of UV chambers and accelerated aging tests, are presented along with their evaluation tests such as dynamic shear rheometry, rutting tests, Fourier infrared spectroscopy, and bending beam rheology. Key indicators used to assess UV aging, including physical properties, rheological parameters, and chemical composition changes, are summarized. The mechanisms underlying UV aging, particularly the changes in asphalt’s structural components and rheological properties, are examined. The impact of factors like radiation intensity, temperature, chemical composition, and asphalt film thickness on UV aging is discussed. Additionally, various additives and modifiers, including modified bitumen, UV shielding agents, UV absorbers, antioxidants, and nanomodifiers, are reviewed for their potential to mitigate UV aging. This paper concludes by highlighting the challenges in developing standardized test equipment and evaluation criteria, the limitations of organic modifiers, and the need for further research on nanomaterials to improve asphalt’s UV aging resistance.