Natural Outdoor Conditions Research Articles

Spruce and pine utilization of phosphorus in soil amended with 33P‐labelled hydroxylapatite

AbstractMined rock phosphate is expected to become a scarce resource within the next few decades as global phosphorus (P) deposits are declining. As a result, mineral P fertilizer will be less available and more expensive. Therefore, improved knowledge is needed on other P resources, for example, apatite fertilizers derived from the by‐products of iron mining. Forestry is a potential future consumer of apatite‐rich products with the aim of obtaining more wood per hectare. The actual P availability in apatite to plants has so far been barely quantified. We therefore examined tree P uptake using 33P apatite under chamber‐grown and outdoor conditions. We examined the P uptake for the two main conifer species spruce (Picea abies) and pine (Pinus sylvestris) used in Fenno‐Scandinavian forestry. We synthesized 33P‐enriched apatite and applied it to mesocosms with growing seedlings of spruce and pine. The P uptake from 33P‐labelled hydroxylapatite was subsequently traced by (bio)imaging of radioactivity in the plants and by liquid scintillation counting (LSC) upon destructive harvest in all plant fractions (leaves, stem and roots) and rhizosphere soil. Two climatic conditions were compared, one at natural outdoor conditions and one set as 5°C warmer than the climate record from the previous years. Plant P uptake from 33P‐labelled hydroxylapatite was enhanced in chamber‐grown compared with outdoor seedlings for both tree species. This uptake was manifested in the clear radioactive images obtained over ca. 1 month after soil apatite application. Furthermore, all aboveground plant fractions of both spruce and pine seedlings showed a higher P uptake in warmer than colder daytime environments. The observed quantities and rates of P uptake from 33P‐labelled hydroxylapatite by spruce (18 Bq g−1 hour−1) and pine (83 Bq g−1 hour−1; averages in chamber condition) are as to our knowledge unique observations. Natural forest soils in Sweden are often P‐poor. Our research suggests that apatite‐based P fertilization of spruce and pine forests can increase wood production by overcoming any existing P limitation.

Effect of UV‐water weathering on the mechanical properties of flax‐fiber‐reinforced polymer composites

AbstractThis study examines the influence of weathering aging on the mechanical properties and durability of flax fiber‐reinforced polymer composites (FFRP) intended for outdoor applications. Employing an accelerated weathering environment replicating natural outdoor conditions, encompassing UV radiation, condensation, and water spray, the FFRP samples with 2 and 4 mm thicknesses underwent exposure durations of 0, 500, 1000, and 1500 h. Mechanical tests characterized tensile, flexural, and inner‐plane shear properties, while a custom‐made apparatus measured the long‐term tensile creep behavior. Additionally, scanning electron microscopy allowed for the observation of microscopic changes in fiber and matrix. The findings illustrate a consistent decline in tensile and flexural properties with increased weathering exposure, resulting in reductions of 17% and 38% in the tensile strength and modulus, and 24% and 52% in the flexural strength and modulus after 1500 h. Intriguingly, inner‐plane shear strength exhibited a slight increase after 500 h before a subsequent decrease. Furthermore, samples with the same thickness demonstrated an increased creep development with longer weathering durations. Despite this, the mechanical degradation rate induced by weathering was comparatively slower for thicker samples. Overall, the diminished mechanical properties of FFRP post‐weathering can be attributed not only to the polymer but also to the substantial role played by flax fibers in this process.Highlights UV weathering degrades the mechanical properties of flax/polyester composites. Both the instantaneous elastic properties and the long‐term creep behavior are affected by weathering. Thickness influences the mechanical degradation of the composites caused by UV weathering. SEM confirmed UV‐water weathering resulted in the degradation of both natural fiber and polymer matrices.

A transcriptional program underlying the circannual rhythms of gonadal development in medaka.

To cope with seasonal environmental changes, organisms have evolved approximately 1-y endogenous circannual clocks. These circannual clocks regulate various physiological properties and behaviors such as reproduction, hibernation, migration, and molting, thus providing organisms with adaptive advantages. Although several hypotheses have been proposed, the genes that regulate circannual rhythms and the underlying mechanisms controlling long-term circannual clocks remain unknown in any organism. Here, we show a transcriptional program underlying the circannual clock in medaka fish (Oryzias latipes). We monitored the seasonal reproductive rhythms of medaka kept under natural outdoor conditions for 2 y. Linear regression analysis suggested that seasonal changes in reproductive activity were predominantly determined by an endogenous program. Medaka hypothalamic and pituitary transcriptomes were obtained monthly over 2 y and daily on all equinoxes and solstices. Analysis identified 3,341 seasonally oscillating genes and 1,381 daily oscillating genes. We then examined the existence of circannual rhythms in medaka via maintaining them under constant photoperiodic conditions. Medaka exhibited approximately 6-mo free-running circannual rhythms under constant conditions, and monthly transcriptomes under constant conditions identified 518 circannual genes. Gene ontology analysis of circannual genes highlighted the enrichment of genes related to cell proliferation and differentiation. Altogether, our findings support the "histogenesis hypothesis" that postulates the involvement of tissue remodeling in circannual time-keeping.

MXene derived Ti3C2/TiO2/Ag persistent photocatalyst with enhanced electron storage capacity for round-the-clock degradation of organic pollutant

Persistent photocatalysis has garnered significant attention due to its ability to sustain catalytic activity in dark by storing electrons. However, the practical application of persistent photocatalysis is hindered by limited electron storage capacity. Herein, we synthesized and demonstrated that Ti3C2/TiO2/Ag persistent photocatalyst has good electron storage capability. The electron storage capacity of Ti3C2/TiO2/Ag is up to 0.125 μmol/mg, which is 2.5 times that of Ti3C2/TiO2. The enhanced electron storage capacity resulted in improved dark-reaction activity because more electrons react with oxygen to form more radicals, as evidenced by degradation experiments of various organics. Especially, persistent photocatalytic degradation of tetracycline hydrochloride by Ti3C2/TiO2/Ag was achieved under natural outdoor conditions (from 2:00p.m. to 8:00p.m.). Additionally, the aid of oxidants such as peroxymonosulfate (PMS) can further improve the dark-reaction activity. TiO2/Ti3C2/Ag/PMS system exhibits excellent efficacy in removing tetracycline hydrochloride, oxytetracycline, rhodamine b, methyl orange, and methylene blue, with removal rates reaching 79.5 %, 81.4 %, 98.9 %, 99.1 %, and 99.2 %, respectively (15 min of light-reaction and 45 min of dark-reaction). This work provides a new strategy to enhance electron storage capacity and demonstrates that decoupling of light-reaction and dark-reaction may provide a new opportunity for photocatalytic removal of pollutants around the clock.

Experimental Study of the Dimensional and Hygrothermal Properties of Hemp Concrete under Accelerated Aging

In this article, the functional properties of hemp concrete are studied. Hemp concrete stands to reduce the carbon impact and improve the energy consumption of houses. Hence, numerous properties are measured: mass and dimension (volume) variations are found, as is the variability in hygrothermal properties (density, thermal conductivity, heat capacity, moisture buffer value, and water vapor permeability). This entry proposes three different characterization campaigns. The first is a short introduction to the spatial variability in thermal conductivity; the second is dedicated to the study of univariate variations in the mass, volume, and hygrothermal properties of hemp concrete samples. The last one tackles the aging evolution of the properties characterized during the second campaign, in which the samples follow several aging protocols, including exposure to outdoor conditions, the application of immersion-drying cycles, and the application of freeze–thaw cycles. A set of samples is kept under control conditions to allow for comparison. As the main result, spatial variability was found in the material. This is related to the random manufacturing variability or the spatial position regarding the height of the manufactured element. A high univariate variability is found across hemp concrete samples. Moreover, the storage of samples under stable reference conditions implies very little change in the studied materials’ properties, whereas all accelerated aging protocols implied major changes of properties. In particular, we observed an evolution of the thermal conductivity of the samples kept under control conditions for 4 months, with the thermal conductivity ranging from −2.7% to +6.3% with a mean evolution of +1.22%. We observed an increase in the same property, ranging from +2.7% to +18.3%, with a mean of +9.0% for samples kept for 4 months under natural outdoor conditions, an increase ranging from +7.3% to +23.6% with a mean of +15.2% for samples that had undergone 20 cycles of immersion-drying, and an evolution of this property ranging from −5.6% to +12.3% for samples that had undergone 20 freeze–thaw cycles.

Microalgal-bacterial granular sludge under constant dark and weak light conditions: Morphology, performance and microbial community

As a sustainable wastewater treatment process, it is unclear whether the microalgal-bacterial granular sludge (MBGS) can adapt to the continuous light-deficiency environment, which hinders the further application of this technology under natural outdoor conditions when the sunlight is insufficient. Herein, this study investigated the performance of MBGS in treating simple and complex organic wastewater under respective constant dark and weak light (20 μ mol m−2 s−1) conditions. It was found that MBGS could survive under constant dark and weak light conditions for approximately 7 and 15 days, respectively. During the initial 7 days' operation, the average removal efficiencies of organics, nitrogen and phosphorus for simple/complex wastewater were 39.0 %/38.1 %, 22.4 %/19.1 % and 58.6 %/29.9 % under dark conditions, which were 55.8 %/80.1 %, 77.8 %/86.7 % and 76.4 %/90.9 % under weak light conditions, respectively. It was observed that weak light promoted the granule size increase and extracellular polymeric substances production of MBGS. Microbial analysis showed that the dark condition was beneficial to Proteobacteria growth of MBGS while weak light was more conducive to the increase of Cyanobacteria. Firmicutes became the main taxa of MBGS under complex carbon source conditions, potentially contributing to the decomposition of complex organics under light-insufficient conditions. This study will advance our knowledge on MBGS under light-limited conditions.

Modulation of macro and micronutrients to enhance lipid production by Scenedesmus abundans in a flat-panel photobioreactor under outdoor natural sunlight

The present study investigates the effect of macro- and micronutrients on photoautotrophic lipid production from Scenedesmus abundans. An optimized lipid medium has been formulated using one-at-a-time variation of macronutrients and a study of micronutrient interactions. Both single-stage and two-stage strategies were used for simultaneous production of lipid and exopolysaccharide (EPS) in medium-scale photobioreactors (PBRs) using the optimized lipid medium. In the single-stage cultivation 32% fatty acid methyl ester (FAME, biodiesel) was achieved, whereas only 12.6% FAME was observed in two-stage PBR. A FAME titer of 1.16 g/L with overall FAME productivity of 32 mg/L/day and 280 mg/L EPS was achieved using the single-stage strategy. Further, under diurnal natural sunlight and outdoor conditions, a FAME content of 46%, with 1.28 g/L of FAME and 27 mg/L/day FAME productivity, and 155 mg/L EPS were achieved using the single-stage strategy in 2 L medium-scale flat-panel PBRs. Apart from high biodiesel and EPS production, this microalgal strain also has the ability to carry out natural autoflocculation with high efficiency. The strain could be exploited for high lipid content under outdoor cultivation without photoinhibition. Highlights Micronutrients have effects on lipid accumulation in Scenedesmus abundans. Scenedesmus abundans produced high biodiesel content (46% of DCW) under natural sunlight. Simultaneous synthesis of multiproducts by this candidate paves the way for biorefining.

Effect of Rhizospheric Fungus on Biological Control of Root Rot (Fusarium equiseti) Disease of Saposhnikovia divaricata

Saposhnikovia divaricata is a high-demand medicinal plant containing various bioactive metabolites (e.g., chromone). However, root rot disease leads to a dramatic reduction in the yield and quality of S. divaricata. The use of rhizospheric microorganisms is one of the best strategies for biological control. In this study, a total of 104 fungi isolated from the rhizospheric soil of S. divaricata plants were examined for their different antifungal properties. Subsequently, strain MR-57 was selected as a potential stock for biocontrol due to its broad-spectrum antagonistic activity against pathogens, including F. equiseti. Based on the analysis of morphological properties and rDNA internal transcribed spacers (ITSs), strain MR-57 was identified as Acrophialophora jodhpurensis (GenBank No. OK287150.1), a newly recorded species for China. In an in vitro antifungal assay, the culture filtrate of strain MR-57 significantly reduced the conidial germination rate and induced alterations in the mycelia morphology of F. equiseti, such as deformation and degradation. To assess the antifungal efficacy of MR-57 against root rot disease and the properties promoting the growth of S. divaricata, pot experiments were performed under natural outdoor conditions. The results indicated that co-inoculation with MR-57 delayed the occurrence of S. divaricata root rot and showed a control efficacy of 65.41% (p < 0.05) based on the measurement of suppressed disease lesions. Additionally, MR-57 successfully colonized and formed a stable population in the soil in which S. divaricata was grown, and it exhibited a consistently positive effect on the promotion of the growth of S. divaricata plants. In short, Acr. jodhpurensis MR-57 could be considered for the development of a potential biocontrol agent for the management of S. divaricata root rot caused by F. equiseti.

Characteristics and Microbiome Profiling of Korean Gochang Bokbunja Vinegar by the Fermentation Process

As NGS (next-generation sequencing) technology develops, metagenomics-based microbial ecology, that is, microbiome research, has recently led to the science of fermented food. Based on the above technology, a study was conducted to understand the characteristics of vinegar made from bokbunja, a local crop in Gochang-gun, Korea. Physicochemical characteristics of vinegar, organic acid analysis, microbial community analysis, and electronic tongue analysis were explored while fermenting the vinegar for 70 days under eight fermentation conditions according to the concentration of bokbunja liquid (100% or 50%), type of fermenter (porcelain jar or stainless container), and fermentation environment (natural outdoor conditions or temperature/oxygen controlled). As a result, distinct microbial community patterns were found in the stage of acetic acid fermentation and, accordingly, this fermentation of Gochang vinegar is classified into three categories. Vinegar prepared by the traditional method of outdoor fermentation using jars showed characteristics of “Acetobacter (42.1%)/Lactobacillus (56.9%) fusion fermentation”. Under conditions where oxygen and temperature were controlled indoors using jars, characteristics of “Komagataeibacter (90.2%) fermentation” were found. “Lactobacillus (92.2%) fermentation” characteristics were discovered under natural outdoor conditions using stainless steel containers. These fermentation pattern differences were related to taxonomic phylogenetic diversity, which was also considered involved in determining organic acid production and taste. These results will be helpful as a scientific basis for understanding the fermentation characteristics of Gochang vinegar and developing high-value-added traditional vinegar products.

Wavelength effect on polymer photooxidation under LED weathering conditions

This paper is devoted to the investigation of the photooxidation of poly(N-vinylcarbazole (PVK) and polyethylene (LDPE) by exposure to λ ≥ 300 nm polychromatic light (SEPAP 12.24) or UV light produced by a new setup equipped with LEDs emitting at 365 nm (LED 365), both at a temperature of 60°C. Photooxidation was studied by infrared and UV-visible spectroscopies and emission spectroscopy in the case of PVK. The mechanisms by which the oxidation products were formed in both polymers were recalled. Depending on the conditions of ageing, i.e., polychromatic light or exposure to LED 365, the same oxidation products were obtained but with different rates and different relative amounts. This result reflected the influence of the wavelengths on the mechanisms. In the case of PVK, the formation of oxidation photoproducts and yellowing were not impacted, but the kinetics of the decrease in excimer fluorescence, which is linked to the crosslinking of the polymer, were dramatically modified. In the case of LDPE, wavelength effects on the photolysis of ketones by Norrish reactions were observed. As a consequence, irradiations with the LED 365 setup could not be claimed to be representative of polychromatic irradiations because the shortest wavelengths (300 nm < λ < 350 nm) were missing and could not reproduce natural outdoor conditions of weathering.

Plasma-Wind-Assisted In2S3 Preparation with an Amorphous Surface Structure for Enhanced Photocatalytic Hydrogen Production.

Photocatalytic production from water is considered an effective solution to fossil fuel-related environmental concerns, and photocatalyst surface science holds a significant interest in balancing photocatalysts’ stability and activity. We propose a plasma-wind method to tune the surface properties of a photocatalyst with an amorphous structure. Theoretical calculation shows that the amorphous surface structure can cause an unsaturated coordination environment to adjust the electron distribution, forming more adsorption sites. Thus, the photocatalyst with a crystal–amorphous (C–A) interface can strengthen light absorption, harvest photo-induced electrons, and enrich the active sites, which help improve hydrogen yield. As a proof of concept, with indium sulfide (In2S3) nanosheets used as the catalyst, an impressive hydrogen production rate up to 457.35 μmol cm−2 h−1 has been achieved. Moreover, after plasma-assisted treatment, In2S3 with a C–A interface can produce hydrogen from water under natural outdoor conditions. Following a six-hour test, the rate of photocatalytic hydrogen evolution is found to be 400.50 μmol cm−2 g−1, which demonstrates that a catalyst prepared through plasma treatment is both effective and highly practical.

Construction of a Simple Domeless Net Radiometer for Demonstrating Energy Balance Concepts in a Laboratory Activity

Even though energy balance concepts are fundamental to solutions of problems in a number of disciplines in the agricultural and life sciences, they are seldom demonstrated in a laboratory activity. Here, we introduce a simple domeless net radiometer to demonstrate how the surface temperature of an object aboveground is regulated by the properties of the surfaces and environmental conditions. The device is based on the early designs of all-wave net radiometers and is composed of a foam disc with its opposing surfaces coated with either white or black paint. Temperatures of the disc’s surfaces are monitored using thermocouple temperature sensors. Using a combination of solar irradiance, albedo of the ground surface, air temperature, and wind speed measurements, the temperatures of the disc’s surfaces can be calculated by means of an energy balance model. We found good agreement between calculated and measured temperatures. In addition to demonstrate important physical concepts under natural outdoor conditions, we believe that the proposed laboratory activity will benefit students by allowing them to gain some experience and practical skills in working with environmental sensors, programming data acquisition systems, and analyzing data. Stimulating students’ creativity as well as developing their analytical and problem-solving skills is another goal of the proposed activity.

Daylighting provision and visual comfort in unilaterally and bilaterally illuminated classrooms

Children between the ages of 6 and 14 spend much of their day in school classrooms, where they are exposed to only a fraction of the daylight quantities typical for natural outdoor conditions. This paper examines unilaterally and bilaterally illuminated classrooms in terms of quantitative and qualitative requirements for daylighting in classrooms during both winter and summer. The results of measurements and simulations pointed out the advantages of bilaterally illuminated classrooms when compared to unilaterally illuminated ones. In winter, the windows placed on two opposite walls provide a significantly higher uniformity of daylight. In summer, in addition to the improved uniformity, this window arrangement offers higher variability in shading strategies, resulting in greater availability of daylight and better visual comfort. These factors can potentially prevent or limit the development of myopia.

Preliminary Valorization of Climatic Conditions Effects on Curing of Air Lime-Based Mortars for Restorative Applications in the Pasargadae and Persepolis World Heritage Sites

Air lime mortars with addition of two types of sesame cooking oil were synthesized and cured in two different conditions: laboratory and natural climatic conditions of the Pasargadae and Persepolis World Heritage Sites. For the mortars cured in the laboratory, addition of oils in the mortar induced hydrophobic effects, but it adversely affected on permeability values and carbonation rates. However, the air lime mortars cured in the site conditions demonstrated increment in their hydrophobicity and superficial durability without retarding their setting time and adverse effects on their calcium carbonate formation values, due to various climatic parameters existing in natural outdoor conditions.

Comparison of dust and high-temperature effects on mono and poly photovoltaic panels

Solar Photovoltaic Panels are considered as one of the most powerful alternative renewable and sustainable energy sources. However, a major challenge is the effect of dust accumulation on the photovoltaic panels in natural outdoor environment as it reduces the transmissivity of the light on the surface of the solar panels. For many small communities, the decision of implementing mono or polycrystalline PVs should consider economic aspects. This study is a case study that is held at The British University in Egypt at El Sherouk city to study the effect of different parameters such as dust accumulation, water cooling and coating on the performance of both mono- and poly-crystalline panels at El-Sherouk City. The effects of high temperature and dust accumulation on different solar panels placed in natural outdoor conditions at El-Sherouk City are studied and the electrical performance of the solar panels is represented by measuring several characteristic parameters of dusty and cooled PV panels compared to cleaned and non-cooled panels. The effect of the tilt angle on the accumulation of dust on the surface of the solar panels is, also, studied. The mono-crystalline solar panels are installed at tilt angles 0°, 15°, 30°, 45°, and 60° for one month without cleaning, by any method. The results shows that the power reduction percentage is 17%,20%,25%,27% and 30% for tilt angles 60°,45°,30°,15° and 0°; respectively. Tilt angles 15° and 30° show to be optimal for the installation of the PV solar system, as they produce the highest amount of output power. It is found from the study that the accumulation of dust on the surface of different types of solar panels can reduce the efficiency by 30%. While the high temperature can reduce the efficiency by up to 10 %.

Acquisition of 3-D trajectories with labeling support for multi-species insects under unconstrained flying conditions

In the work presented here, a new technique based upon stereo vision is proposed to acquire three-dimensional time-resolved trajectories with labeling support for multi-species insects under unconstrained flying conditions. A low-cost, off-the-shelf depth camera is used for stereo vision which is equipped with two wide-angle global-shutter IR imagers to compute depth map and a separate narrow-angle color imager to have color and texture information. Two novel strategies are employed to tackle the challenges imposed by the small size of insects, fast movements, and natural daylight, etc.; (i) introduction of a simple but robust technique for detection and tracking of insects using only the valid depth map data and subsequently to acquire 3-D trajectories (ii) object localization scheme for the insects in acquired trajectories in allied color frames based upon the analysis of insects' flying kinematics and their 3-D location coordinates. The object localization of flying insects in allied color frames provides support to label the multi-spp. trajectories with respective types of the species. The proposed technique provides completely generalized solution to acquire 3-D trajectories of the multi-spp. insects in natural outdoor conditions and in the presented work it is applied to acquire the trajectories of honey bees (Apis mellifera) and invasive hornets (Vespa spp.) near beehives. These hornets are serious honey bee stressors and cause severe damage to the hive's foraging force. The trajectory patterns of honey bees together with Vespa spp. can be analyzed for early detection of Vespa spp. near beehives as well as to estimate stress levels on the honey bees. Acquired 3-D trajectory data are validated for trajectory measurements as well as for the labeling support information. A mean error upper bound of 5 mm is estimated in trajectory measurements whereas 100% inter-spp. and up to 94% intra-spp. labeling support accuracies are recorded.

Effects of Biochar on Sediment Transport and Rill Erosion after Two Consecutive Years of Seasonal Freezing and Thawing

This research explored the effects of biochar on slope runoff and sediment transport processes and the hydrodynamic mechanism of rill erosion under the seasonal freeze–thaw climate in the black soil area of Northeast China. The four slopes of 1.8, 3.6, 5.4 and 7.2° were set, corn straw biochar was used, and three biochar contents of 0 kg m−2 (B0 treatment), 6 kg m−2 (B6 treatment) and 12 kg m−2 (B12 treatment) were applied. The experimental plot was placed outdoors to simulate the freeze–thaw cycle of sloping farmland under natural conditions. Three artificial simulated rainfall tests were carried out before the end of seasonal freeze–thaw cycles and spring sowing date (May) in 2018 and 2019. The sediment transport process of runoff and the variation of hydrodynamic parameters in rills were analyzed under one and two seasons of freezing and thawing in natural outdoor conditions. The results show that biochar has a positive effect on reducing rainfall runoff and soil loss after one year and two years of seasonal freezing and thawing. The effect of biochar on the sediment concentration of slope runoff increased with increasing application time; in the second year, the B6 and B12 treatments reduced the sediment concentration by 5.5–14.8% and 3.3–13.6%, respectively, compared with the values of the first year. The Reynolds number (Re) in the rill flow after the B6 and B12 treatments decreased with increasing duration, which effectively reduced the turbulence degree of the flow on the rill of the slope. With the increase in duration, the rill critical erosion power increased; in 2018 and 2019, the critical shear force, critical runoff power and critical unit runoff power were 0.403 Pa, 0.098 m s−1, and 0.002 N m−1 and 0.497 Pa, 0.124 m s−1, and 0.003 N m−1, respectively. This result indicates that increasing the duration and number of seasonal freeze–thaws can promote the development of biochar control of the runoff and sediment processes on slope and rill development.

Effect of Dust and High Temperature on Photovoltaics Performance in the New Capital Area

The trend for integrating solar Photovoltaic Panels as an alternative renewable and sustainable energy source is growing in Egypt, North Africa and the Middle East. However, these efforts are not widely accepted by the society due to their lower efficiencies. The efficiency of the photovoltaic panels is affected by many environmental parameters, which have a negative impact on system efficiency and cost of energy, dust and increased panel temperatures being the most serious. This work presents the results of a case study conducted at The British University in Egypt at El-Sherouk city to study the effect of different parameters such as dust accumulation, water cooling and coating on their performance of both mono- and poly-crystalline panels at El-Sherouk City. The effects of high temperature and dust accumulation on different solar panels placed in natural outdoor conditions at El-Sherouk City were studied and the electrical performance of dusted, cleaned, and cooled PV panels is presented. The variation in the efficiency of mono-crystalline panels installed at different tilt angles, resulting from the accumulation of dust on their surface, was also studied. The results showed that the accumulation of dust on the surface of different types of solar panels can reduce the efficiency by 30%. While the high temperature can reduce the efficiency by up to 10 %. The results showed that the power reduction percentage was 17%, 20%, 25%, 27% and 30% for tilt angles 60°,45°,30°,15° and 0°; respectively. Tilt angles 15° and 30° showed to be optimal for the installation of the PV solar system, as they resulted the highest amount of output power

Experimental performance evaluation of an impinging jet with fins type solar air heater.

The current experimental investigation aimed to evaluate performance of a non-cross flow type solar air heater (SAH). The design comprises of an array of continuous longitudinal fins which extends the bottom of absorber surface and alongside to it a jet plate with inline holes has also been encapsulated. The experiments were performed in natural outdoor conditions for a specified range of flow and geometrical parameters, namely, {[Formula: see text], 5700≤ Re ≤ 11700,0.046 ≤ Dj/Dh ≤ 0.076, andX/Dh, w/Dh = 0.23, 0.46}, respectively. The key indices such as temperature rise parameter (TRP) and collector thermal efficiency are chosen to analyze the performance characteristics of collector. The influence of the above listed parameters on these constraints has been investigated in details. As a function of the entire range of geometrical parameters, an increase in the air flow rate degrades the value of TRP. At the same situation, collector thermal efficiency was found to increase. The peak values of TRP were obtained between 12:00 and 01:00 pm. The rise in air temperature corresponding to hourly deviation of solar intensity has been interpreted at different fin spacing ratios. Furthermore, a parametric optimization approach is employed to identify the optimum values of fin and jet plate parameters yielding maximum collector thermal efficiency. The obtained data have been worked out to plot the design curves for fin and jet parameters. The experimental results were validated with similar literature. The comparative analysis reports a maximum enhancement in TRP of 20.5 % at Dj/Dh = 0.076. The percentage improvement in collector thermal efficiency of 16.4% at w/Dh = 0.23 and 9.8% at Dj/Dh = 0.076 has also been noted with reference to compared works.

Human thermal climate of the Carpathian Basin

AbstractA human body–clothing–atmosphere environment system energy balance model is constructed to evaluate individual human thermal climates in the Carpathian Basin. The analysis is performed in terms of clothing resistance and operative temperature for the period 1971–2000. The model's main strength is that it simulates the metabolic activity rate M as simply as possible taking into account interpersonal variations. Non‐sweating, walking humans are considered in natural outdoor conditions at a walking speed of 4 km⋅h−1. Atmospheric data are used from the CarpatClim dataset; human data are taken from a Hungarian human dataset. The dataset reveals that the interpersonal variations of M of walking humans can reach 40–50 W⋅m−2. According to the results, the variability of individual human thermal climates can be significant. This variability increases towards cold climates and is less in the comfortable thermal zone, when the operative temperature is between 23 and 28°C. It should be mentioned that summer is thermally neutral in the Little Hungarian Plain, the Great Hungarian Plain and in larger parts of the Transylvanian Plateau, irrespective of the person considered. The warmest areas in the Carpathian Basin can be found in Bačka and Banat. In terms of thermal sensation, the results obtained agree well with the results referring to the human considered in the Physiological Equivalent Temperature index model.