Maximum Ambient Temperature Research Articles

Performance evaluation of solar dryer integrated with solar panel for drying of carrot (Daucus carota) vegetable

ABSTRACT Solar energy is a well-known and economically efficient energy source. Solar energy is harvested in two modes: one is direct and another is indirect. In the direct type, the global radiation is used directly to dry the food samples, while in indirect mode, solar energy is converted into electricity to operate the integrated exhaust fan for enhancement of the drying rate. Thermal analyses of the various components of the PVT hybrid dryer have been incorporated into this performance evaluation. Carrot has been chosen as a food sample because it has good moisture content and is used for nutritive purposes. The maximum ambient temperature has been monitored as 41°C at maximum global radiation conditions. The effect of the PVT system with solar dryer in both cases i.e. natural convection and forced convection have also been discussed in terms of temperature profiles of the drying chamber, sample temperature, and thermal efficiency. The thermal efficiency has been found as 55.3% for forced convection and 53.4% for natural convection. Similarly, a 3°C temperature increment has been found in food samples. Results have been supported and analyzed by the comparison between outcomes of natural and induced convection.

Effect of frequent clearcutting on some soil properties, temperatures, and herbaceous vegetation and the potential of their recovery in a short time.

Harvesting or degradation of forest ecosystems directly affects the microclimate, causing changes in air and soil temperatures and soil moisture in the forestlands. The objectives of this study were to investigate the effect of frequent clearcutting of forest cover on some selected soil properties, ambient and soil temperatures, soil moisture, and herbaceous vegetation cover and determine their recovery in a short period in the area subject to frequent clearcutting under the powerline corridors (PLCs). The study was conducted in the research forest of Istanbul University-Cerrahpaşa, Faculty of Forestry. The treatment plots were selected from the clearcut area, and control plots were selected from an untouched oak-hornbeam forestland. Soil temperature and moisture and maximum and minimum ambient temperatures were measured in the treatment and control plots between 2020 and 2021 and topsoil sampled between 2019 and 2021. Data were analyzed using analysis of variance (ANOVA) to test the effects of clearcutting on some selected soil properties in the short term after cutting. Clearcutting caused a significant increase in soil bulk density (BD) and a decrease in the soil total porosity (TP), soil hydraulic conductivity (HC), and saturation capacity (SC). Forest cover removal significantly decreased the soil organic matter (SOM) content by 3%, increased average soil temperature by 2.1°C, and the difference between maximum and minimum temperatures by 8.8°C. Additionally, clearcutting reduced the average soil moisture from 36 to 35%. The findings revealed that clearcutting negatively affected some hydro-physical soil properties and soil microclimate conditions that may not recover to their previous states within the next few years.

Design and Construction of a Mixed-Mode Natural Convection Solar Dryer for Mango Slices

Fruits like mangoes are produced in large quantities during the peak season, and high postharvest losses occur due to lack of appropriate storage and handling structures. The main goal of this study was to design and construct a mixed-mode natural convection (MMNC) solar dryer for drying of mango slices. The dryer was designed using AutoCAD and constructed with wood and glass using basic woodworking tools and processes. The developed dryer has a direct collector, a vertical collector, and an indirect collector. The drying chamber has two removable frames with 5 shelves each, a total drying area of 2.54 m2 and a capacity of 10 kg of mango slices per batch. The dryer is fitted with caster wheels for easy turning and positioning. Test conducted with 940 g of fresh mango slices resulted in effective drying after 17 hours, from a moisture content of approximately 90% (wb) reduced to 17% (wb). The drying rate was found to be 4.3%/hr. The maximum temperature obtained in the drying chamber was 54.3 ℃ at a maximum ambient temperature of 37.6 ℃. The average temperature-rise in the drying chamber compared to the ambient temperature was 11.5 ℃. The dryer is therefore recommended for use both domestically and by small-scale food processors since it is more hygienic and has proven to be more efficient than open-air sun drying.

Effects of floral resources on honey bee populations in Mexico: Using dietary metabarcoding to examine landscape quality in agroecosystems.

The decline of honey bee populations significantly impacts the human food supply due to poor pollination and yield decreases of essential crop species. Given the reduction of pollinators, research into critical landscape components, such as floral resource availability and land use change, might provide valuable information about the nutritional status and health of honey bee colonies. To address this issue, we examine the effects of landscape factors like agricultural area, urban area, and climatic factors, including maximum temperature, minimum temperature, relative humidity, and precipitation, on honey bee hive populations and nutritional health of 326 honey bee colonies across varying landscapes in Mexico. DNA metabarcoding facilitated the precise identification of pollen from 267 plant species, encompassing 243 genera and 80 families, revealing a primary herb-based diet. Areas characterized by high landscape diversity exhibited greater pollen diversity within the colony. Conversely, colonies situated in regions with higher proportions of agricultural and urban landscapes demonstrated lower bee density. The maximum ambient temperature outside hives positively correlated with pollen diversity, aligning with a simultaneous decrease in bee density. Conversely, higher relative humidity positively influenced both the bee density of the colony and the diversity of foraged pollen. Our national-level study investigated pollen dietary availability and colony size in different habitat types, latitudes, climatic conditions, and varied levels and types of disturbances. This effort was taken to gain a better insight into the mechanisms driving declines in honey bee populations. This study illustrates the need for more biodiverse agricultural landscapes, the preservation of diverse habitats, and the conservation of natural and semi-natural spaces. These measures can help to improve the habitat quality of other bee species, as well as restore essential ecosystem processes, such as pollination and pest control.

Assessing responses to heat in a range-shifting, nocturnal, flying squirrel.

Over the last few decades North American flying squirrels (Glaucomys spp.) have experienced dramatic northward range shifts. Previous studies have focused on the potential effects of warming winter temperatures, yet the hypothesis that rising summer temperature had a role in these range shifts remained unexplored. We therefore sought to determine the effect of high environmental temperatures on the thermoregulation and energetics of flying squirrels in an area of the Northeast of North America with a recent species turnover. Unable to find a logistically feasible population of the northern species (Glaucomys sabrinus), we focused on Southern Flying Squirrels (G. volans). Using flow-through respirometry, we measured the relationship between metabolic rate, evaporative water loss, and body temperature at high ambient temperatures. We also measured core body temperature in free-ranging flying squirrels using temperature-sensitive data loggers. We detected no significant increase in metabolic rate up to ambient temperatures as high as 40 °C. However, evaporative water loss increased at temperatures above 36.2 °C. Free-ranging body temperature of flying squirrels followed a circadian pattern with a ~2 °C difference between active and resting phase modal body temperatures. Rest-phase body temperatures were influenced by environmental temperatures with higher resting temperatures observed on days with higher daily maximum ambient temperatures but not to an extent that energy or water costs were significantly increased during rest. We found that, due to a relatively high level of thermal tolerance, high ambient temperatures are unlikely to cause an energetic strain on Southern Flying Squirrels. However, these findings do not preclude negative impacts of high ambient temperatures on the northern species, and these may still play a role in the changing distributions of Glaucomys in North America.

Investigation of thermal performance, drying characteristics and environomical analysis: direct flow evacuated tube solar drying of okra.

A direct flow evacuated tube solar dryer (DF_ETSD), a novel drying system, was used for drying pre-treated okra (Abelmoschus esculentus). The performance of DF_ETSD was analysed by determining thermal profiling, dryer and collector efficiency hourly. The maximum 3-day average ambient temperature, collector outlet temperature and solar radiation were 35.6°C, 66.4°C and 976 W m-2 respectively. The collector efficiency increased as solar radiation increased over time due to a higher temperature difference between the collector outlet and ambient temperature. The maximum collector and dryer efficiency observed were 30.19% and 21.47%, respectively. A pre-treatment of okra was done in hot water at 70, 80 and 90°C for 5min. Okra samples were dried from an initial moisture content of 87.42 ± 1.49% (wb) to a final value of 10.77 ± 1.03% (wb) in 9h. The pre-treatment temperature of 80°C is suitable for maximum drying rate, colour retention and rehydration ratio and minimum water activity, which signifies the longer shelf-life of okra. Midilli and Kucuk model was best fitted (highest R2, lowest χ2 and RMSE) for the control and samples pre-treated at 80°C; however, Verma model was suitably fitted for the sample pre-treated at 70 and 90°C. The payback period of DF_ETSD was found to be 1.27years. Environmental analysis shows the CO2 emission and net CO2 mitigation ranged between 1.24 and 18.65 t and 9.86 and 154.05 t respectively for different selected lifecycles of the dryer. Due to its environmental sustainability and low payback period, the presented drying system is recommended for okra and other fruits and vegetables.

Improving hydration in underhydrated, free-living young adults results in better running performance

Dehydration impairs endurance exercise performance, especially in the heat. However, it is unclear how exercise performance is affected by improved hydration status in underhydrated individuals. Therefore, this study examined the impact of a one-week hydration intervention on endurance running performance. We hypothesized better hydration would lead to a faster 2-mile running time. Eighty-nine healthy and moderately fit individuals completed a 2-mile run as fast as possible before (PRE) and after (POST) a 1-week hydration intervention. Performance was incentivized by providing prize money based on ranked average times. First-morning urine samples were collected on the day of each run. If PRE urine specific gravity was >1.020, the subjects were instructed to increase their water intake for one week before the second run. The remaining subjects were instructed to maintain their water intake. All subjects were provided with a filter water bottle. Of the 89 subjects that completed both runs, 44 (18% female, age: 21±2 y, weight: 73.3±12.5 kg, height: 1.76±0.10 m, body mass index: 23.6±3.2 kg/m2) were included in the analysis. Subjects were classified as improved hydration (IMP) if UOsm decreased between PRE and POST by ≥100 mmol/kg and POST was <800 mmol/kg. Subjects were classified as diminished hydration (DIM) if UOsm increased between PRE and POST by ≥100 mmol/kg and POST was >500 mmol/kg. The subjects were removed from the analysis if they met any of the following three conditions: a) had a small UOsm change (<100 mmol/kg) between PRE and POST, b) lowered UOSM but it was still >800 mmol/kg, and c) increased UOsm but it was still <500 mmol/kg. The 2-mile runs took place in Phoenix, Arizona, during the morning (0700 hours) with a maximum ambient temperature of 22±2℃, relative humidity of 37±10%, and WBGT of 16±2℃. UOsm significantly decreased for IMP from PRE: 791±197 to POST: 419±136 mmol/kg (p<0.05) and increased for DIM from PRE: 532±283 to POST: 799±235 mmol/kg (p<0.05). The 2-mile run time significantly improved in IMP from PRE: 13.5±1.8 to POST: 13.3±1.8 min (-11.4±25.8 sec, P=0.03), but did not change in DIM from PRE: 14.2±2.7 to POST: 14.3±2.6 min (+4.8±19.9 sec, P>0.05). The results suggest that improving hydration in underhydrated subjects via one week of increased water intake may improve 2-mile running performance in moderately fit individuals. This study was funded by a grant from the Arizona State University’s Global Sport Institute. Brita donated the filter water bottles. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Anthropogenic heat from buildings in Los Angeles County: A simulation framework and assessment

Anthropogenic heat (AH), i.e., waste heat from buildings to the ambient environment, increases urban air temperature and contributes to the urban heat island effect, which leads to more air-conditioning energy use and higher associated waste heat during summer, forming a positive feedback loop. This study used a bottom-up simulation approach to develop a dataset of the annual hourly AH profiles for 1.7 million buildings in Los Angeles (LA) County for the year 2018 aggregated at three spatial resolutions: 450 m, 12 km, and the census tract. Building AH exhibits strong seasonal and diurnal patterns, as well as large spatial variations across the urban areas. Building AH peaks in May and reaches a maximum of 878 W/m2 within one of several AH hotspots in the region. Among the three major AH components (surface convection, heat rejection from HVAC systems, and zonal air exchange), the surface convection component is the largest, accounting for 78% of the total building AH across LA County. Higher AH is attributed to large building density, a high percentage of industrial buildings, and older building stock. While AH peaks during the day, the resulting ambient temperature increases are much larger during the night. During the July 2018 heatwave in LA County, building AH (excluding the surface component) leads to a daily maximum ambient temperature increase of up to 0.6 °C and a daily minimum ambient temperature increase of up to 2.9 °C. It is recommended that reducing summer building AH should be considered by policy makers in developing mitigation measures for cities to transition to clean energy while improving heat resilience.

Modelling Europe-wide fine resolution daily ambient temperature for 2003–2020 using machine learning

To improve our understanding of the health impacts of high and low temperatures, epidemiological studies require spatiotemporally resolved ambient temperature (Ta) surfaces. Exposure assessment over various European cities for multi-cohort studies requires high resolution and harmonized exposures over larger spatiotemporal extents. Our aim was to develop daily mean, minimum and maximum ambient temperature surfaces with a 1 × 1 km resolution for Europe for the 2003–2020 period. We used a two-stage random forest modelling approach. Random forest was used to (1) impute missing satellite derived Land Surface Temperature (LST) using vegetation and weather variables and to (2) use the gap-filled LST together with land use and meteorological variables to model spatial and temporal variation in Ta measured at weather stations. To assess performance, we validated these models using random and block validation. In addition to global performance, and to assess model stability, we reported model performance at a higher granularity (local). Globally, our models explained on average more than 81 % and 93 % of the variability in the block validation sets for LST and Ta respectively. Average RMSE was 1.3, 1.9 and 1.7 °C for mean, min and max ambient temperature respectively, indicating a generally good performance. For Ta models, local performance was stable across most of the spatiotemporal extent, but showed lower performance in areas with low observation density. Overall, model stability and performance were lower when using block validation compared to random validation. The presented models will facilitate harmonized high-resolution exposure assignment for multi-cohort studies at a European scale.

Seasonal Changes in the thermal tolerances of Odontophrynus occidentalis (Berg, 1896) (Anura: Cycloramphidae)

We studied the thermal tolerances of Odontophrynus occidentalis during the dry and wet seasons of the Monte Desert in San Juan Province, Argentina. This toad had differences in CTmax between dry and wet seasons, with CTmax values being greater in the wet season (Austral summer). Operative temperature, body temperature, and environmental maximal temperature were related to CTmax suggesting seasonal acclimatization in O. occidentalis. Additionally, the CTmax recorded for O. occidentalis was 36.1ºC, and the maximum ambient temperature measured during the toads’ activity time was 37ºC. The CTmin of O. occidentalis was 4.1ºC while the minimum environmental temperature recorded was 7.2 ºC. The wide tolerance range observed and the relationship between tolerance limits and the environmental extremes indicate that seasonal acclimatization is an effective mechanism by which toads can raise their thermal tolerance. This is a highly relevant adaptation allowing them to survive in the challenging conditions of the Monte Desert.

Consideration of Temperature Factors when Designing Butterfly Check Valves for Hazardous Production Facilities

The safety of hazardous production facilities is directly related to the reliability of pipeline systems, which must be ensured regardless of environmental conditions. Accidents on pipeline sections can have catastrophic consequences associated with damage to human health and the environment. Damage to the metal of pipeline elements during operation due to internal corrosion occurring under the influence of the working fluid is one of the main reasons for failure. This study aims to develop an improved butterfly check valve (BCV), which is a pipeline element. For this purpose, various structural materials used in the production of check valves were analyzed, and the changes in their mechanical properties under the influence of temperature were also considered. Based on this material, a butterfly check valve was developed. The stress-strain state of the developed structure was assessed using the finite element method (FEM). Strains, stresses, and displacements were calculated to evaluate valve performance. These calculations are necessary to determine the most loaded elements of the BCV at the maximum and minimum ambient temperatures. The following conclusions were obtained: X6CrNiTi18-10 stainless steel grade is the most suitable material for piping systems transporting liquids in production facilities. On the basis of the simulation results, the values of equivalent stresses, maximum strains, and displacements were obtained. The research results confirmed the performance of the improved design, the unhindered motion of the working fluid in the working direction, and the convenient connection to horizontal and vertical sections of the pipeline. Doi: 10.28991/CEJ-SP2023-09-020 Full Text: PDF

Comparative study of energy performance and water savings between hygroscopic and rankine cycle in a nuclear power plant. Case study of the HTR-10 reactor

The use of nuclear energy can contribute to achieving positive socio-economic and environmental benefits, but nuclear power plants are one of the most water-intensive industries in the world. The use of Small Modular Reactor (SMR) technologies is increasing due to their interesting advantages such as reduction of construction costs and use in remote areas, which favors distributed generation. Hygroscopic Cycle Technology (HCT) can be of great interest for power generation in nuclear power plants, due to the potential improvement in terms of energy efficiency and water savings. This study presents the benefits of implementing HCT in an existing SMR, the HTR-10, based on the classical Regenerative Rankine Cycle (RRC). The HTR-10 is used to produce electricity and thermal energy for District Heating (DH). Analytical models of both cycles have been developed to compare them in terms of energy production and water consumption. Sensitivity analyses of the influence of the main variables have been performed. The results show that by varying the condensing pressures, the thermal power for DH and the net mechanical power production of the HCT increase up to 2.5 % and 1 %, respectively, with respect to the RRC. The maximum tolerable ambient temperature for the plant with the HCT is 43.12 °C, increasing the availability of the plant and avoiding water consumption between 70000 and 88000 m3/year, depending on the operating conditions. Extrapolation of the results suggests that HCT can improve the energy production of nuclear power plants in a more sustainable way, contributing significantly to the energy transition.

Контроль качества светодиодных COB матриц по пороговому току

A description of a method for measuring the threshold current, the minimum current at which optical emission is occurs, of chips that are part of COB (chip on board) LEDs is given. The method consists in registering with a digital camera the average values of the emission intensities of the chips at three small values of the electric current and determining the threshold currents by solving a system of equations relating the measured intensities to a function approximating the P-I characteristic in the range of low currents. The measurement method was tested on commercially available COB LEDs consisting of ten series-connected chips. It was determined that the values of the threshold current of the chips differ: for the investigated samples, the coefficient of variation ranged from 2.6% to 39.2%. As a result of the tests of COB LEDs under the action of a current of 140 mA at a maximum allowable ambient temperature of 110 °C for 11 days, it was found that changes in the average values of the threshold currents during tests correlate with changes in the current-voltage characteristics of the matrices measured in the voltage range from 17 to 24 V at which leakage current dominates: the threshold current increases for those matrices in which leakage current increases. The correlation coefficient between the relative changes in the leakage current and the average values of the threshold currents is 0.94. It is shown that the correlation coefficient between the magnitude of the decline in the luminous flux of the matrices during testing and the change in the average value of the threshold current is 0.96. The established strong correlations show the possibility of diagnosing the quality by the threshold current of individual chips in the composition of COB LEDs.

Enhancing the Efficiency of Bi-Facial Photovoltaic Panels: An Integration Approach

This work presents a novel approach to increasing the efficiency of photovoltaic (PV) panels by integrating them with a cooling tower (CT). An infusion of water cools the hot, dry ambient air at the top of the CT. Due to gravity, the cooled air drops toward the base of the CT, where it interacts with a turbine placed at the bottom of the CT to produce electricity. The air then exits the CT base, creating a cooled air jet stream. The PV panels were placed at the base of the CT, right at the stream’s exit. As the cooled air passes underneath the PV panels, it exchanges energy with the PV, reducing the panels’ temperature. The results showed that the maximum annual efficiency improvement (6.831%) was observed using two rows of PV panels. The efficiency declined incrementally from 6.831% to 4.652% when the number of rows of PV panels was increased from two to twelve. The results also showed a significant improvement in the temperature of the PV panels. The best results were obtained at noon (maximum ambient temperature), where the solar panel temperature was lowered to 25 °C from 55 °C. Furthermore, the annual electrical energy generated with two rows of panels was 39,207.4 kWh without the CT, compared to 41,768.2 kWh with the CT. In addition, the results showed that with a 10 m diameter and 200 m height CT, the maximum number of PV rows that can be effectively cooled is 24. Future work will investigate integrating additional techniques to improve the system’s efficiency further.

Thermal design of a system for mobile hydrogen powersupply

Ever more stringent emission regulations for vehicles encourage increasing numbers of battery electric vehicles on the roads. A drawback of storing electric energy in a battery is the comparable low energy density, low driving range and the higher propensity to deplete the energy storage before reaching the destination, especially at low ambient temperatures. When the battery is depleted, stranded vehicles can either be towed or recharged with a mobile recharging station. Several technologies of mobile recharging stations already exist, however, most of them use fossil fuels to recharge battery electric vehicles. The proposed novel zero emission solution for mobile charging is a combined high voltage battery and hydrogen fuel cell charging station. Due to the thermal characteristics of the fuel cell and high voltage battery (which allow only comparable low coolant temperatures), the thermal design for this specific application (available heat exchanger area, zero vehicle speed, air flow direction) becomes challenging and is addressed in this work. Experimental methods were used to obtain reliable thermal and electric power measurement data of a 30 kW fuel cell system, which is used in the Mobile Hydrogen Powersupply. Subsequently, simulation methods were applied for the thermal design and optimisation of the coolant circuits and heat exchangers. It is shown that an battery electric vehicle charging power of 22 kW requires a heat exchanger area of 1 m2, of which 60 % is used by the fuel cell heat exchanger and the remainder by the battery heat exchanger to achieve steady state operation at the highest possible ambient temperature of 43,6 °C. Furthermore, the simulation showed that when the charging power of 22 kW is solely provided by the high voltage battery, the highest possible ambient temperature is 42 °C. When the charging power is decreased, operation up to the maximum ambient temperatures of 45 °C can be achieved. The results of maximum charging power and limiting ambient temperature give insights for further system improvements, which are: sizing of fuel cell or battery, trailer design and heat exchanger area, operation strategy of the system (power split between high voltage battery and fuel cell) as well as possible dynamic operation scenarios.

Distribution And Abundance of Flamingos (Phoenicopteriformes: Phoenicopteridae) In the Salt-Affected Wetlands of The Peruvian Andes

This study investigates the distribution and abundance of flamingos (Phoenicopteriformes: Phoenicopteridae) in salted high-Andean wetlands of Peru. These wetlands are located at an altitude between 3 200 and 4 600 meters above sea level and represent key habitats for these birds. However, there is little information about the presence of flamingos in these environments and their relationship with salinity. To analyze the distribution and abundance of flamingo species in the salted wetlands of the Peruvian Andes. Sampling was carried out in 11 wetlands over a period of time from August to October 2021. Both adult and juvenile individuals were recorded, and data on physicochemical water parameters and environmental variables were collected. They reveal interesting patterns regarding the distribution and abundance of flamingos in these salted wetlands. It was observed that the Loriscota wetland harbors the largest population of flamingos, with a total of 14 750 individuals belonging to the species Phoenicopterus chilensis, Phoenicoparrus andinus, and Phoenicoparrus jamesi. Among these species, Phoenicopterus chilensis was the most abundant. Furthermore, a positive correlation was found between the presence of flamingos and certain environmental and physicochemical parameters. Water pH, maximum ambient temperature, and relative humidity showed a significant association with the presence of flamingos in the wetlands. This study provides important information about the distribution and abundance of flamingos in the salted high-Andean wetlands of Peru, which will contribute to the understanding of interactions between flamingos and their habitat. Additionally, they will serve as a basis for future conservation and management strategies for these species and the wetlands.

Reduced parental brood visit rate in wild zebra finchesTaeniopygia castanotisis correlated with high maximum daily ambient temperature

As a result of a warming global climate, understanding how organisms adjust their behaviour to environmental thermal conditions has become an increasingly important question in animal biology. Temperature‐driven adjustments in parental care are potentially important given the repercussions on offspring size, quality and survival. In 2015 and 2016 we monitored parental care for 83 zebra finchTaeniopygia castanotisbreeding attempts in the wild with known brood sizes. We recorded the frequency of parental visits to the nest together with mean maximum ambient temperature experienced between day 7 and 14 of the nestling period. We found that for each increase of 1°C in the daytime temperature there was a 0.91% reduction in the hourly rate of parental visits, whilst also accounting for other variables such as nestling age, time of season, and wind speed. Our data suggest that nestlings may receive less food under thermally challenging conditions, which is consistent with recent studies that demonstrate offspring are smaller when reared during periods of high temperature. Understanding the behavioural drivers that may contribute to the production of smaller offspring in extreme heat conditions could prove useful to forecast long‐term consequences for fitness triggered by climate change.

Ambient temperature prediction model and cooling requirement analyze in the high-altitude construction tunnel passing through the abnormally high geothermal region

The investigation of the ambient temperature distribution in tunnels with abnormally high temperatures during the construction period, as well as the calculation of the cooling demand around the working face are important for high-temperature tunnels. After analyzing the heat transfer mechanism of one-end ventilation, the finite difference method was applied for establishing the ambient temperature forecast model. In addition, the ambient temperature variation characteristics were explored combination with tunnel geotemperature distribution considering the impacts of wind temperatures and volumes. The following are the main conclusions: (1) The difference between predicted data and actual monitoring data, which was less than 0.077. (2) When the air leakage rate is reduced from 5% to 1%, the maximum ambient temperature is reduced by 2.2 ℃, and the location of the highest ambient temperature moved away from the working face. (3) The ambient temperature distribution (from the tunnel excavation face to the entrance) showed a growing and then decreasing trend when the tunnel construction length was in the range of 2000 m. And as the construction length extended to 2990 m, the ambient temperature distribution showed the trend of increasing → decreasing → increasing → decreasing. (4) As the wind volume was greater than 120 m3/s and the wind temperature was below 10 °C, there was no cooling capacity gap within 100 m of the tunnel excavation face.

Neuro-fuzzy systems for daily solar irradiance classification and PV efficiency forecasting

Considering the impact of photovoltaic installations and the fact that their performance depends on the type of day, this paper presents a classifier that makes use of fuzzy logic to classify daily irradiance profiles as a human would do. To do this, the system must be linguistically interpretable, so the classifier must be simple enough, but without losing accuracy. This is why the article combines the use of data mining and supervised learning algorithms to obtain an initial system and then exploits simplification techniques such as the concept of fuzzy classifiers with incomplete rule bases, as well as fuzzy tabular simplification of rules to obtain a compact and simple final system. The classifier obtained handles the ambiguity presented by the daily irradiance profiles with precision. Once the system has been obtained, a large number of days in southern Spain are classified, analysing the performances of a photovoltaic plant obtained in each of the classes. Then, a neuro-fuzzy system is designed to predict the performance of the photovoltaic installation, considering the type of day, the maximum ambient temperature reached during the day, and the degradation of the installation over time, proving its usefulness in alerting about anomalous behaviour of the system.

Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere

Cool materials and rooftop vegetation help achieve urban heating mitigation as they can reduce building cooling demands. This study assesses the cooling potential of different mitigation technologies using Weather Research and Forecasting (WRF)- taking case of a tropical coastal climate in the Kolkata Metropolitan Area. The model was validated using data from six meteorological sites. The cooling potential of eight mitigation scenarios was evaluated for: three cool roofs, four green roofs, and their combination (cool-city). The sensible heat, latent heat, heat storage, 2-m ambient temperature, surface temperature, air temperature, roof temperature, and urban canopy temperature was calculated. The effects on the urban boundary layer were also investigated.The different scenarios reduced the daytime temperature of various urban components, and the effect varied nearly linearly with increasing albedo and green roof fractions. For example, the maximum ambient temperature decreased by 3.6 °C, 0.9 °C, and 1.4 °C for a cool roof with 85% albedo, 100% rooftop vegetation, and their combination.The cost of different mitigation scenarios was assumed to depend on the construction options, location, and market prices. The potential for price per square meter and corresponding temperature decreased was related to one another. Recognizing the complex relationship between scenarios and construction options, the reduction in the maximum and minimum temperature across different cool and green roof cases were used for developing the cost estimates. This estimate thus attempted a summary of the price per degree of cooling for the different potential technologies.Higher green fraction, cool materials, and their combination generally reduced winds and enhanced buoyancy. The surface changes alter the lower atmospheric dynamics such as low-level vertical mixing and a shallower boundary layer and weakened horizontal convective rolls during afternoon hours. Although cool materials offer the highest temperature reductions, the cooling resulting from its combination and a green roof strategy could mitigate or reverse the summertime heat island effect. The results highlight the possibilities for heat mitigation and offer insight into the different strategies and costs for mitigating the urban heating and cooling demands.