Reflectance Values Research Articles

Rubidium Halide Additive Engineering for Efficient and Stable Bifacial Perovskite Solar Cells

AbstractBifacial perovskite solar cells (PSCs) possess a dual light‐absorbing structure, which enables higher power output at lower additional costs. However, the replacement of metal electrodes with transparent ones leads to serious light loss, necessitating a thicker perovskite layer to compensate for this drawback. In this study, the impact of different rubidium halide (RbCl, RbBr, and RbI) additives is systematically investigated on precursor solubility and the quality of micron‐sized perovskite thick films prepared using a two‐step method. It is observed that RbCl exhibited the strongest interactions with PbI2, enhancing its solubility and leading to the formation of multihole PbI2 films that promote subsequent crystallization of thick perovskite film. Additionally, the RbCl‐based perovskite film demonstrates a narrowed bandgap attributed to the formation of a‐FAPbI3. Consequently, the short‐circuit current density (Jsc) and open‐circuit voltage (Voc) in the RbCl‐based bifacial PSCs are simultaneously enhanced, and a record efficiency of 20.86% (21.04% certified) is also obtained among n‐i‐p bifacial PSCs, exhibiting an ≈80% bifaciality and a power generation density (PGD) exceeding 24 mW cm−2 with a reflectivity value of 0.2. More importantly, the optimized device does not show any performance degradation after continuous illumination under 1sun for 1000 h.

Frequency dependence of reflections on radar landmarks

Purpose. Reducing the dispersion of radar reflections from local objects, with multi-frequency sensing, to solve the problem of orientation by radar reflections from objects. Methodology. Reflections from local objects in the entire frequency range of the radar station (RS) at the same radio engineering position were measured by three independent radars of the same type on different days and at different antenna elevations. The deviation of the radar stations in the position did not exceed 500 meters. Coordinates (azimuth, range) of reflections of several separate local objects were allocated for each radar. The average values of reflections from local objects and their dispersion in the frequency range were calculated. Using various algorithms, individual frequencies were sampled and the reflected signals were averaged at these frequencies. The decrease in the dispersion of the reflected signal from the number of frequencies at which reflections were measured and from the algorithm for selecting these frequencies was investigated. Findings. Averaging the values of reflections from local objects for several frequencies leads to a decrease in dispersion and, as a result, to a more accurate correspondence of the reflected signal level to the geometric size of the local object. The variance decreases most rapidly for a small number of frequencies selected for averaging when selecting frequencies located in an interval of at least 1% relative to each other. Originality. To solve the problem of orientation based on radar reflections from local objects, it is necessary to identify the landmarks selected on a digital terrain model. Due to the fact that local objects (hills) are a collection of many reflectors falling into the allowed volume of the radar, with different levels of reflections and random phases, there may not be radar reflection from a local object at a certain frequency, or it may be very small. In order to unambiguously identify all landmarks, measurements must be carried out at several frequencies. The work has established how many frequencies measurements should be performed at and on what principle these frequencies should be selected. Practical value. The advent of digital terrain models made it possible to solve the problem of terrain orientation by comparing radar reflections from local objects with reflection models based on digital terrain maps. Radar reflection models use mathematical expectations of reflection values, unlike real reflections, which have random deviations in signal levels depending on the operating frequency. Reducing the variance of these deviations increases the accuracy of identifying characteristic local objects (landmarks) used to orient the radar in the absence of data from satellite navigation systems.

On the Epistemic Value of Reflection

Against philosophical orthodoxy, Kornblith (2012) has mounted an empirically grounded critique of the epistemic value of reflection. In this paper, I argue that this recent critique fails even if we concede that the empirical facts are as Kornblith says they are, and assume that reliability is the only determinant of epistemic value. The critique fails because it seeks to undermine the reliability of reflection in general but targets only one of its variants, namely individual reflection, while neglecting social reflection. This critique comprises two arguments which have a common structure: they both impose a requirement on the reliability of reflection, but deny, on empirical grounds, that the requirement is met. One argument imposes an introspection requirement, which I reject as superfluous. I show how reflection can proceed without introspection. The other argument imposes an efficacy requirement. This requirement concerns whether reflection is causally efficacious i.e., whether it leads us to change our minds for the better. I accept this as a genuine requirement. Even if we concede that individual reflection fails to meet this requirement, I argue that we have not been given sufficient evidence to believe that social reflection is bound to violate this requirement. Furthermore, my analysis of the conditions under which social reflection works best provides us with prima facie grounds for optimism regarding the reliability of social reflection. Ultimately, then, these arguments fail to undermine the epistemic value of reflection in general.

Relative Radiometric Normalization for the PlanetScope Nanosatellite Constellation Based on Sentinel-2 Images

Detecting and characterizing continuous changes on Earth’s surface has become critical for planning and development. Since 2016, Planet Labs has launched hundreds of nanosatellites, known as Doves. Despite the advantages of their high spatial and temporal resolution, these nanosatellites’ images still present inconsistencies in radiometric resolution, limiting their broader usability. To address this issue, a model for radiometric normalization of PlanetScope (PS) images was developed using Multispectral Instrument/Sentinel-2 (MSI/S2) sensor images as a reference. An extensive database was compiled, including images from all available versions of the PS sensor (e.g., PS2, PSB.SD, and PS2.SD) from 2017 to 2022, along with data from various weather stations. The sampling process was carried out for each band using two methods: Conditioned Latin Hypercube Sampling (cLHS) and statistical visualization. Five machine learning algorithms were then applied, incorporating both linear and nonlinear models based on rules and decision trees: Multiple Linear Regression (MLR), Model Averaged Neural Network (avNNet), Random Forest (RF), k-Nearest Neighbors (KKNN), and Support Vector Machine with Radial Basis Function (SVM-RBF). A rigorous covariate selection process was performed for model application, and the models’ performance was evaluated using the following statistical indices: Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Lin’s Concordance Correlation Coefficient (CCC), and Coefficient of Determination (R2). Additionally, Kruskal–Wallis and Dunn tests were applied during model selection to identify the best-performing model. The results indicated that the RF model provided the best fit across all PS sensor bands, with more accurate results in the longer wavelength bands (Band 3 and Band 4). The models achieved RMSE reflectance values of approximately 0.02 and 0.03 in these bands, with R2 and CCC ranging from 0.77 to 0.90 and 0.87 to 0.94, respectively. In summary, this study makes a significant contribution to optimizing the use of PS sensor images for various applications by offering a detailed and robust approach to radiometric normalization. These findings have important implications for the efficient monitoring of surface changes on Earth, potentially enhancing the practical and scientific use of these datasets.

Covid-19 and its related environmental quality issues along ganga river, Varanasi, India

COVID-19 made people around the world in terrifying and appalling circumstance which held back all collaborative stitches that is the government decreed people to stay in homes for suppressing the disease spread amid people. Pandemic situation due to Covid-19 has lead to worldwide lockdown. On the other hand, it has increased the quality of the environment especially in hydrosphere and atmosphere progressively throughout the world. The global shutdown from March to June 2020 made liable in assessing the environmental condition which is eccentric accomplishment when collating with past two decades. This study demonstrates change in the water and aerosol quality with the aid of remote sensing in Ganga River of Varanasi city, Uttar Pradesh state of India. Sentinel data obtained from February to July of 2020 used to determine the variation of pollution levels during different phases of lockdown. NO2 levels derived from Sentinel data shows hazardous level of 5.64x10-5mol m-2 in March which is progressively decreased to 5.29 x10-5mol m-2 for the month of April. NO2 level further gradually increased after the unlock 1.0. Similarly, CO levels obtained from Sentinel data shows hazardous level of 0.0517mol m-2 in February which is progressively decreased to 0.0490 mol m-2 for the lockdown periods and it was gradually increased after the unlock phase. Further, Landsat data has been used to show Suspended Particulate Matter and pollution variation between lockdown phases. The high concentration of SPM value for March month ranges from -48.7773 to -48.7812 ,there is drastic decrease in concentration of SPM in which reflection value ranges from -48.7772 to -48.7806 in month of April noticed in the study area.Again there is drastic increase in July values ranging from -48.7753 to -48.7796 which is very high when compared to the lockdown SPM levels.The present study brought to light significant variations in the pollution level during the lockdown phases.

Assessing the Impact of Environmental Conditions on Reflectance Values in Inland Waters Using Multispectral UAS Imagery

This study investigates the impact of environmental conditions on reflectance values obtained from multispectral Unmanned Aerial System (UAS) imagery in inland waters, focusing on sun glint, cloud glint, wind-generated waves, and cloud shading projections. Conducted in two reservoirs with differing water qualities, UAS platforms equipped with MicaSense Altum and DJI Phantom 4 Multispectral sensors were used to collect multispectral images. The results show that sun glint significantly increases reflectance variability as solar elevation rises, particularly beyond 54°, compromising data quality. Optimal flight operations should occur within a solar elevation angle range of 25° to 47° to minimize these effects. Cloud shading introduces complex variability, reducing median reflectance. Wind-generated waves enhance sun glint, increasing variability across all spectral bands, while cloud glints amplify reflectance non-uniformly, leading to inconsistent data variability. These findings underscore the need for precise correction techniques and strategic UAS deployment to mitigate environmental interferences. This study offers valuable insights for improving UAS-based monitoring and guiding future research in diverse aquatic environments.

Mineralogical and Maturation Considerations of the Coqueiros Formation (Campos Basin, Brazil): Insights from Multi-Technique Analyses of Source Rocks

The Coqueiros Formation, a strategic stratigraphic unit within the Lagoa Feia Group (LFG) in the Campos Basin offshore Brazil, is known for its lacustrine carbonate deposits, which include both organic-rich shales and economically important “coquina” reservoirs. While coquina facies are widely recognized as reservoirs, the source-rock potential of the intercalated shales remains relatively underexplored. This study aims to characterize the mineralogy and thermal maturity of the Coqueiros Formation to assess its potential as a source rock, using a multi-technique approach integrating X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Raman spectroscopy analyses of shale samples from two wells: 3-BP-11-RJS and 6-DEV-18P-RJS. XRD analyses revealed a heterogeneous mineralogy dominated by carbonates (calcite and dolomite) and quartz, with significant contributions from clay minerals and trace minerals such as pyrite and barite. SEM imaging revealed a heterogeneous fabric with grain size, morphology, and porosity variations, reflecting a dynamic lacustrine depositional setting influenced by storm events and fluctuations in terrigenous input. The presence of authigenic minerals, as reported in other studies, such as saddle dolomite, mega-quartz, and various sulfides, provides evidence for hydrothermal alteration, likely related to Late Cretaceous magmatic activity in the Campos Basin. Raman spectroscopy yielded equivalent vitrinite reflectance (Ro%) values consistently exceeding 1.00, ranging from 1.03 to 1.40, indicating that the organic matter in the Coqueiros Formation shales has attained a high thermal maturity level, surpassing the oil window and reaching the condensate wet gas zone. The mineralogical and equivalent maturation data presented herein provide a valuable foundation for future studies, highlighting the complexity and heterogeneity of the Coqueiros Formation and its potential significance as a source rock within the Campos Basin petroleum system.

A Comparative Analysis of Parent–Child Interaction Therapy Procedures Used to Facilitate Verbalizations by Children with Autism

AbstractThe current study conducted a comparative analysis of the effects of select components of Parent–Child Interaction Therapy, labeled praise, behavior descriptions, and reflections on child vocalizations in two children with autism spectrum disorder and accompanying language delays using a concurrent multiple baseline across participants design. The frequency of verbalizations, the frequency of different verbalizations, and the mean length of utterance of words (MLUw) were measured during a baseline condition followed sequentially by two experimental conditions during a free play environment. The total number of therapist–child interactions remained consistent across all experimental conditions such that only the topography of the interactions varied across conditions. During the first experimental condition the clinician used labeled praise and behavior descriptions during child play. After establishing stability of changes under these conditions, the therapist systematically added reflections of child vocalizations in the second experimental condition. Total verbalizations, different verbalizations, and MLUw increased following the introduction of labeled praise and behavior descriptions. Total verbalizations and different verbalizations increased and the frequencies accelerated following the systematic introduction of reflections. The study showed the relative value of reflections of child verbalizations as a powerful component of Parent–Child Interaction Therapy procedures to facilitate verbalizations by children with autism.

First principles investigations of linear and nonlinear optical, radiation shielding and thermoelectric properties of the non-centrosymmetric Ba-based chalcogenides Ba2In2X5 (X=S, Te)

We explore the structural, elastic, optoelectronic, Radiation Shielding, and thermoelectric properties of Ba2In2X5 (X = S, Te) using first-principles computations and semi-classical Boltzmann Transport equations. These materials are classified as semiconductors exhibiting band gaps of 2.0 eV and 3.0 eV for both investigated NLO compounds that have more significant direct band gaps of superior optical birefringence and second-order NLO coefficients. The bonding properties have been investigated by analyzing the electron charge density (ECD) contour of the (1 0 1) crystallographic plane. It is clear from the reflectivity spectra that both compounds have a high degree of reflectivity, which could make them useful as UV and visible light shields. From 0 to 14.0 eV, the approximated reflectivity values, R (ω), are displayed against the incident photon energy. Therefore, the reflectivity is around 30 % before E ≈ 12.0 eV and 40 % reflection at ∼13.0 eV. Phase matching is possible for both compounds detected, as shown by the birefringence computations. Furthermore, the radiation shielding properties of Ba2In2S5 and Ba2In2Te5 have been evaluated using Phy-X software, demonstrating their potential effectiveness in medical and nuclear energy applications. The thermoelectric properties display N-type nature at low temperatures when the Seebeck coefficient changes from N to P-type at higher temperature ranges. These compounds have remarkable optical and thermal properties, rendering them highly attractive materials for thermoelectric and optoelectronic devices.

Photocatalysis, wettability and optical properties of N-doped Cu2O/CuO thin films for smart coating applications

Abstract Undoped and nitrogen (N)_doped Cu2O/CuO thin films were deposited via reactive DC magnetron sputtering. The deposition was carried out by sputtering the Cu targets under various Ar/N2/O2 gas flow ratios. The structural, optical, wettability, and photocatalytic performance of the deposited films were investigated. A simple cubic Cu2O crystallographic phase is observed for the undoped film, whereas mixed cubic Cu2O and monoclinic CuO phases (Cu2O/CuO) are observed for the N_doped films. EDAX revealed that as the N2 flow rate increased the amount of nitrogen incorporated into the film increased. The transmittance and reflectance are affected by the incorporation of nitrogen into the films. The transmittance values decreased with increasing N2 flow rate, whereas the reflectance values increased. Both the refractive index and extinction coefficient almost increased with increasing N2 flow rate. A noticeable optical band gap narrowing from 2.55 eV to 2.39 eV was detected upon increasing the N2 flow from 0.0 to 190 sccm. The photoluminescence spectrum of the undoped sample contains five distinct bands at 518, 612, 654, 714 and 825 nm. These five maxima are attributed to the radiative decay of bound and free excitons, and oxygen vacancies (VO) After nitrogen incorporation, the photoluminescence intensity decreases and then increases again with increasing N2 flow rate. A reduction in the water contact angle was observed with increasing N2 flow rate. Upon Vis-light illumination, the N_doped Cu2O/CuO films reached superhydrophilicity faster than the undoped film did. The photocatalytic performance of the deposited Cu2O/CuO films was strongly enhanced with a small amount of N doping. The deposited films are promising for self-cleaning and photocatalytic degradation of organic wastes.

Comparative analysis of spectroradiometric and chemical methods for nutrient detection in black gram leaves

This study evaluated the nutrient content in Vigna mungo leaves using a visible near-infrared spectroradiometer (VNIR 650–900 nm) and compared it with traditional chemical analysis. Nutrient deficiencies were induced in a controlled environment, focusing on Nitrogen (N), Phosphorus (P), and Potassium (K). The VNIR spectroradiometer measured the spectral reflectance of the leaves at different intervals. Peak reflectance for N, P, and K deficiencies occurred at 716 nm, 737 nm, and 720 nm, respectively. A 30 % deficiency in N, P, and K resulted in reflectance values of 45 %, 42 %, and 41 %, respectively, while a 40 % deficiency increased these values to 48 %, 46 %, and 43 %. Results showed a strong correlation between nutrient deficiency and spectral reflectance, providing a quicker, more economical method than traditional chemical analysis. The study concludes that VNIR spectroradiometry is an effective tool for non-destructive, real-time assessment of nutrient status in Vigna mungo, which could lead to optimized fertilizer application and improved crop management.

Unveiling the main drivers of tree decline in Zagros semi-arid forests

Abstract Tree decline in arid and semi-arid forest ecosystems causes severe socioeconomic and ecological problems and thus needs to be thoroughly quantified and monitored across space and time. This study investigates tree and forest decline in Iran’s Zagros forests, considering environmental factors (e.g. topographic, soil, and climatic variables). We used field data from Chaharmahal-and-Bakhtiari (a study area covering 165 km2) and environmental data derived from freely available databases. Relationships between tree, forest decline, and environmental data were analyzed using generalized additive models. Our findings reveal that slope and the BioClim-16 variable (precipitation of the wettest quarter) significantly influence tree decline across various decline classes (P-values: slope = .009, BioClim-16 = .02). The best multivariate model for forest decline incorporated soil organic carbon and silt as predictive variables, with soil organic carbon emerging as the key factor (P-value = .04). Additionally, a spectral analysis of bare soil in declining and non-declining areas consistently demonstrated reduced reflectance values in declining regions across 10 Sentinel-2 bands, with VNIR-3, SWIR-2, red, green, and blue bands consistently showing significant differences as unveiled by the Wilcoxon test in all seasons except winter. These reduced reflectance values may indicate that forests stocked on soils with larger grain size (a higher fraction of sand) and/or higher organic carbon content may be more vulnerable to decline. This study contributes to our hitherto understanding of the main drivers of tree and forest decline in semi-arid forests, among others underscoring the potential utility of the spectral properties of bare soil in sparse semi-arid forests to predict the likelihood of tree decline.

Change of bioactive properties, spectral reflectance, and color characteristics of European cranberry (Viburnum opulus L.) juice as affected by foam mat drying technique

The European cranberry bush, known for its health benefits, can only be consumed through fermentation. This study aimed to develop a fruit leather made from European cranberry bush using quince seed gel and the foam drying method. For this purpose, quince seed gel was added to European cranberry juice to increase consistency. Then, European cranberry fruit leather was obtained by drying at 70, 80, and 90 °C air temperatures using foam mat drying technology. Spectral reflectance, color, drying kinetics, anthocyanin, ascorbic acid, and total phenolic content, antiradical activity, and macro-micronutrient concentrations of the resulting fruit pulp were investigated. The foam mat drying process at 90 °C had the greatest values of ascorbic acid (0.996 mg g− 1), anthocyanin (275.9 mg kg− 1), DPPH (47.77%), and ABTS.+ (68.76 µg TE g− 1). In addition, the highest value of total phenolic content (37.75 mg g− 1) was obtained in the foam mat drying process at 80 °C. The highest concentration of P, Na, Mg, K, Ca, and Mn in fruit leather was obtained at 70 °C, and the highest concentration of S, Cu, and Zn was obtained at 90 °C. The lowest spectral reflectance values were measured at 90 °C. In conclusion, the present study explored the fact that adding quince seed gel, extremely rich in biochemical content, significantly enhanced the bioactivity properties of European cranberry bush fruit leather.

Structural analysis of fossilized tree trunks from the Miocene Mydlovary Formation of the South Bohemian Basin (Czech Republic)

Tree trunks were found in situ in Miocene strata of the Mydlovary Formation of the South Bohemian Basin. Our study presents microscopic and chemical tissue analyses of these tree trunks. The trees were fossilized and flattened. However, they are well preserved, which made the analyses feasible. Good preservation of the tissues is indicated by the high Tissue Preservation Index, the high content of cellulose, and the slightly gelified state of the wood. The Gelification Index indicated that there was only limited alteration during diagenesis. Huminite macerals prevailed over liptinite and inertinite macerals, and two varieties of ulminite and textinite were distinguished, differing in colour reflection, light fluorescence, and reflectance values. The biomarker composition in the extracts of the fossil wood obtained by gas chromatography-mass spectrometry, included terpenoid signatures, supporting a relationship to the Family Cupressaceae s.s.. Gradual burial of the trees is indicated by the fact that they lay crosswise on top of each other. The character of the sedimentary environment and the physiological differences of the trees could explain the deformation and the high degree of preservation.

Application of Low-Temperature Air Plasma for the Enhancement of Defense Fabric's Self-Cleaning Property.

Self-cleaning textiles have the potential to revolutionize the lives of people like military personnel and hikers who spend extended periods of time in the sun and have restricted access to washing facilities. This research aims to develop the self-cleaning capability of defense uniforms by utilizing air plasma treatment and applying TiO2 nanocoating. Following plasma treatment of differing durations (2, 4, 6, 8, and 10 min, respectively), a pad-dry cure method was employed to apply a TiO2 coating to each sample, while keeping other processing parameters constant. SEM, Fourier transform infrared spectroscopy, ultraviolet protection factor (UVPF), energy-dispersive X-rays, and a water contact angle test were performed in order to validate the air plasma-induced surface modification. There was a gradual escalation in the rate of TiO2 absorption with an extension of the plasma treatment duration. Afterward, the samples were stained with various organic and inorganic compounds, including oil, ink, soil, and coffee, and subsequently exposed to sunlight for a period of 6 h. The samples demonstrated an enhanced cleaning effectiveness with increasing quantities of TiO2. The reflectance value and visual assessment of washed sample showed a reduced yet still present self-cleaning characteristic. The UVPF of the samples increased gradually as the duration of plasma treatment increased due to the UV absorption properties of TiO2, as validated by measuring the band gap energy.

Petrographic and geochemical signatures of the Upper Permian Gondwana coals: Newcastle Coal Measures, Northern Sydney Basin, Australia

This research presents an integrated approach to organic petrographical and geochemical characteristics of the Upper Permian Newcastle Coal Measures outcropping in the northern Sydney Basin, southeast Australia. Twenty-seven coal, coaly mudstone and mudstone samples were collected and analyzed by using organic petrography (maceral composition and vitrinite reflectance) techniques, Rock–Eval pyrolysis, bitumen extraction and gas chromatography - mass spectrometry (GC–MS). The obtained results indicate that the samples exhibit promising gas-prone source rock potential and contain a predominantly terrestrial in origin organic matter, with limited contribution by marine organisms. The prevalence of terrestrial organic matter is inferred by the presence of collotelinite and sporinite macerals in most of the samples and the ternary plot of C27, C28 and C29 regular steranes. Further, the low C27/C29 ratio, the cross-plots of C27/(C27 + C29) regular steranes vs. Pr/Ph ratio, the C27/C29 vs. Pr/Ph and the C24 tetracyclic/C26 tricyclic terpane ratio point also to the terrestrial origin of the organic matter. The obtained values of vitrinite reflectance, Tmax, OEP27–31 and CPI25–33, along the cross plots of 20S/(20S + 20R) versus ββ/(ββ + αα) suggest that the samples are immature and were subjected to a low burial depth. The examined samples indicate accumulation in a delta-plain environment of deposition, under fluctuating oxic/anoxic conditions, in a humid climatic zone that is characterized by dry periods, interrupting the longer-termed humid climatic regime. This research adds knowledge on the source rock potential in the northern Sydney Basin and on the environmental and climatic setting of a time interval just prior to the major Permian - Triassic climatic crisis.

Differential mineral diagenetic evolution of lacustrine shale: Implications for CO2 storage

Understanding the differential diagenetic evolution of different lithofacies is essential for assessing the spatial development of shale reservoirs. These insights are crucial in predicting sealing integrity and storage capacity for sequestered CO2. In this study, we examined seven wells from the Cretaceous Qingshankou Formation in the Songliao Basin, China, with vitrinite reflectance (Ro) values ranging from 0.60 % to 1.62 %. Thin section-based petrographic observations, coupled with QEMSCAN analysis, were used to classify the different lithofacies. X-ray diffraction (XRD) analysis of clay minerals, field emission scanning electron microscope (FE-SEM), and energy-dispersive spectrum (EDS) analyses were employed to analyze the mineral textures, pore types, and diagenetic pathways. The results showed that early diagenetic mineral phases include calcite cement (1st phase), framboidal and microcrystalline pyrite, ferroan and non-ferroan dolomite. Intermediate diagenetic mineral phases were marked by illitization of smectite, chlorite formed by chloritization of smectite and alteration of K-feldspar, and the formation of authigenic albite and quartz, calcite cement (2nd phase) and ankerite. Given the higher potential reaction rate of CO2-fluid‑carbonate systems, we propose that the lithofacies dominated by carbonate minerals are not effective for CO2 storage, even in short-term. In contrast, lithofacies rich in feldspar and clay minerals are likely to be more effective for long-term CO2 storage.

Temperature adaptive passive daytime radiative cooling: The impact of their essential properties on energy performance of different building types

Passive daytime radiative cooling (PDRC) materials can reduce building cooling demands during hot periods but increase heating needs in colder times, known as heating penalties, limiting their practicality. Temperature adaptive (TA) materials offer a solution, yet optimal TA PDRC properties, such as changes in reflectivity or emissivity from high surface temperature (HST) to low surface temperature (LST) states and the switch temperature at which these changes occur, are under-researched. To address this, a wavelength-dependent PDRC model was coupled with EnergyPlus to identify the optimal reflectivity or emissivity in HST and LST states and determine the appropriate switch temperature. Results show that different reflectivity and emissivity values are needed for various climates to maximize TA PDRC benefits. Switch temperatures from 15 °C to 30 °C primarily affect cooling benefits with minimal impact on heating penalties. Additionally, the heating penalty and cooling benefit of TA PDRC vary across building types, requiring alignment between TA PDRC operational characteristics and HVAC systems to optimize advantages. Among building types, malls benefit the most from PDRC application.

Structural, electronic, optical and thermoelectric properties of FrSnI3-xClx (X=0, 1, 2, 3) perovskites using the TB-mBJ approach

Mixed halide inorganic perovskites represent a significant advance in energy conversion materials, with research on these materials paving the way for more sustainable and accessible energy solutions. In this work we investigated the effects of chlorine atom substitution on the structural, electronic, optical and thermoelectric properties of mixed halide perovskites FrSnI3-xClx (x=0, 1, 2, 3). The FP-LAPW approach within the Wien2k package has been employed, using the modified Becke-Johnson potential (TB-mBJ) for the exchange correlation functionals. For FrSnI3 and FrSnCl3 the calculated lattice parameters are in good agreement with theoretical results.The formation energies calculated for FrSnI3-x Clx (x = 0, 1, 2, 3) confirm the thermodynamic stability of all these materials. Analysis of the electronic properties, including partial density of states (PDOS), total density of states (TDOS) and band structures, indicates that these materials exhibit p-type semiconductor behaviour with direct band gaps ranging from 1.169 to 1.953 eV. In terms of optical properties, the FrSnI3-xClx compounds exhibit high optical absorption (α(ω) > 104 cm−1) in the visible region. The broad absorption range extends from visible to ultraviolet energy. The low reflectivity values observed (below 30%) and their minimal energy loss suggest potential applications in optoelectronic devices. The thermoelectric properties of these materials were also studied over a temperature range of 100 to 950 K. They exhibit high Seebeck coefficients, high electrical conductivity, and low thermal conductivity. Notably, at room temperature, FrSnI2Cl and FrSnICl2 show the highest figures of merit, reaching 1.31 and 0.61, respectively, demonstrating their high efficiency for thermoelectric devices

Effect of Atmospheric Mixing on Spectral Reflectivity in Sentinel Images of Baghdad Province

The lowest layer of the atmosphere is called the atmospheric mixed layer, characterized by small-scale, irregular air motions defined by winds that change in speed and direction. Aerosol radiative effects impact the atmospheric boundary layer (ABL), which holds most aerosols in the lower atmosphere. Aerosol absorption and scattering both lower the quantity of solar energy that reaches the ground, which has an impact on the spectral signature of the land coverings. In this study, 51 locations in downtown Baghdad were chosen for four different types of land cover (water bodies, farms, open areas, and residential areas) for Sentinel 2 satellite imagery, and the time the pictures were taken was 8:00 am ( 22 March, 22 June, 20 September, and 22 December) 2021. Their spectral reflectance was calculated at the NIR band using a mathematical equation in the ArcGIS program for Sentinel 2 satellite images that had been processed and analyzed. Also, atmospheric boundary layer height and solar radiation values were downloaded for the same date as the satellite images and compared with the spectral reflectivity values of the land covers(agriculture area, residential area, open area, and river) and knowing the effect of the mixing layer and solar radiation on the spectral reflectance values. The highest value of spectral reflectivity, mixing layer height, and solar radiation was in June at (0.065, 1965.524629, and 897.7088) respectively. The spectral reflectivity of plants at near-infrared (NIR) was higher than the rest of the earth’s features because plants reflect near-infrared radiation and absorb the red and blue parts of the spectrum.