Direct Radiation Research Articles

Effects of diffuse radiation fraction on crop light absorption, light use efficiency and gross primary production on an instantaneous scale in South China.

The fraction of absorbed photosynthetically active radiation (FAPAR), light use efficiency (LUE), and gross primary productivity (GPP) are the key driving factors of crop production and ecological models. Diffuse radiation fraction (DF) has been reported to profoundly affect FAPAR, LUE and GPP, and its impact on a short time scale needs to be emphasized. Based on the field observations at noon local time during 2021-2022 and the Two-Leaf light use efficiency model, this study investigated the magnitudes of the DF effect on the canopy FAPAR, LUE, and GPP for the three different crops (peanut, soybean and corn) on an instantaneous scale in South China. Different from that of peanut and soybean, the FAPAR of corn increased linearly with the rise of DF. The instantaneous LUE of each crop was highly sensitive to DF, and its linear regression slope was greater than 1.0g C MJ- 1. On average, the DF accounted for around 69-74% of the variations in the instantaneous LUE and 59-64% of the variations in the instantaneous GPP over the entire observation period. The sky conditions with a DF value between 0.45 and 0.66 were favorable for the carbon fixation of the three crops. The linear coupling strength between GPP and PAR under diffuse radiation (DF ≥ 0.5) was stronger than that under direct radiation (DF < 0.5). The results will be helpful in accurate estimating of FAPAR, LUE, GPP and even crop production in both South China and other similar regions.

Free-electron resonance transition radiation via Brewster randomness

Free-electron radiation, such as Cherenkov radiation and transition radiation, can generate light at arbitrary frequencies and is fundamental to diverse applications, ranging from electron microscopy, spectroscopy, lasers, to particle detectors. Generally, the features of free-electron radiation are stochastic when electrons interact with random media. Counterintuitively, here, we reveal a type of free-electron radiation that has both its intensity and directionality invariant to specific sorts of long-range structural randomness. Essentially, this invariance is enabled by the Brewster effect and the judiciously engineered phase coherence condition of emitted light, namely that the light induced by electron's penetration through a layered aperiodic nanostructure is engineered to interfere constructively at the Brewster angle. As such, when each constituent layer with a random thickness fulfills this phase coherence condition, there is always the emergence of free-electron resonance transition radiation at the Brewster angle. At this resonant Brewster angle, we further find that the radiation intensity and directionality could be enhanced by orders of magnitude by readily increasing the interface number. The revealed resonance transition radiation via long-range Brewster randomness may offer a feasible route to explore more enticing photonic applications driven by free electrons, such as light sources at previously unreachable spectral regimes, optical frequency combs, particle detectors, and random lasers.

Forecasting Heat Power Demand in Retrofitted Residential Buildings

The accurate prediction of heat demand in retrofitted residential buildings is crucial for optimizing energy consumption, minimizing unnecessary losses, and ensuring the efficient operation of heating systems, thereby contributing to significant energy savings and sustainability. Within the framework of this article, the dependence of the energy consumption of a thermo-modernized building on a chosen set of climatic factors has been meticulously analyzed. Polynomial fitting functions were derived to describe these dependencies. Subsequent analyses focused on predicting heating demand using artificial neural networks (ANN) were adopted by incorporating a comprehensive set of climatic data such as outdoor temperature; humidity and enthalpy of outdoor air; wind speed, gusts, and direction; direct, diffuse, and total radiation; the amount of precipitation, the height of the boundary layer, and weather forecasts up to 6 h ahead. Two types of networks were analyzed: with and without temperature forecast. The study highlights the strong influence of outdoor air temperature and enthalpy on heating energy demand, effectively modeled by third-degree polynomial functions with R2 values of 0.7443 and 0.6711. Insolation (0–800 W/m2) and wind speeds (0–40 km/h) significantly impact energy demand, while wind direction is statistically insignificant. ANN demonstrates high accuracy in predicting heat demand for retrofitted buildings, with R2 values of 0.8967 (without temperature forecasts) and 0.8968 (with forecasts), indicating minimal performance gain from the forecasted data. Sensitivity analysis reveals outdoor temperature, solar radiation, and enthalpy of outdoor air as critical inputs.

Direct radiation pressure measurements for lightsail membranes

Direct radiation pressure measurements for lightsail membranes

Free-form surface-based polar-axis rotational direct solar radiation spectrum measurements

Accurate measurements of direct solar radiation spectra are crucial for atmospheric science, climatology, agriculture, and solar energy. Existing systems depend on costly dual-axis tracking devices, leading to high maintenance and error rates. This study presents a free-form surface-based polar-axis rotating solar direct radiation spectrometer, enabling year-round measurements across all latitudes without mobile tracking. The system operates in the 380–780 nm range with a spectral resolution better than 2 nm. Simulation results demonstrate spectral curve area errors between 0.68% and 1.22%, and outdoor experiments in Changchun, China, confirm the accuracy of measurements against the AM1.5 G standard.

Reduction of the microbial background in the intensive care unit of a surgical hospital with the systematic introduction of the Alpha‑06A pulsed ultraviolet system into disinfection measures (experimental study)

Relevance. Healthcare-associated infections (HAIs) are a significant problem in intensive care units. They contribute to increased mortality, lengthen hospital stays and increase treatment-related costs.The aim of the study was to evaluate the effectiveness of reducing the microbial background and cross-transmission of pathogenic microorganisms associated with the provision of medical care in the intensive care units of surgical hospital with the systemic use of the Alpha‑06A pulsed ultraviolet system with the “Areal” device (Scientific and Production Enterprise «Melitta», Russia).Materials and methods. The Alfa‑06A air, surface and local areas disinfection system with the “Areal” device was used in the intensive care unit for 2 months – August and September 2024. The “Areal” device directs ultraviolet radiation, generated by the pulsed xenon lamp of the Alfa‑06 installation, into a limited sector. The rest of the room is structurally protected from direct UV radiation. It is allowed to use it in the presence of patients and staff. The use of the installation complemented the standard anti-epidemic measures. At the end of the study period, the results of microbiological studies were retrospectively evaluated and compared with the results of the control period.Results. A statistically significant (Fisher’s criterion 0.00383, p&lt;0.05) tenfold decrease in the number of positive samples from surfaces during the treatment period in the «Areal» mode was noted. A decrease in bacterial pollution of the environment led to a distinct tendency to reduce cases of contamination of patients with various bacterial flora, and the acquisition by the patients of multidrug-resistant organisms statistically significantly decreased by 100 % (p&lt;0.5). As a result, the use of the Alpha system in the «Areal» mode reduced the cost of expensive antibacterial drugs by 18.9 % in absolute and 7.4 % in relative terms.Conclusion. The systematic use of Alfa‑06A in conjunction with the “Areal” device in the daily work of the intensive care unit significantly reduces the contamination of surfaces with microorganisms. This is reflected in a decrease in the number of positive samples from various patient loci. The number of cases of persistence of polyresistant problematic bacteria of the ESKAPE group is also decreasing. The improvement of the microbiological background shows a clear economic effect in terms of the cost of expensive antibacterial drugs.

Exciton Emission Enhancement in Two-Dimensional Monolayer Tungsten Disulfide on a Silicon Substrate via a Fabry-Pérot Microcavity.

Exciton emitters in two-dimensional monolayer transition-metal dichalcogenides (TMDs) provide a boulevard for the emerging optoelectronic field, ranging from miniaturized light-emitting diodes to quantum emitters and optical communications. However, the low quantum efficiency from limited light-matter interactions and harmful substrate effects seriously hinders their applications. In this work, we achieve a ∼438-fold exciton photoluminescence enhancement by constructing a Fabry-Pérot cavity consisting of monolayer WS2 and a micron-scale hole on the SiO2/Si substrate. The overall enhancement results from the increased exciton-photon interaction due to the effective exciton-cavity mode coupling and decreased trion formation from the weakened substrate effect confirmed by transient spectroscopy. Moreover, the effective coupling improves the directivity of excitons' spontaneous radiation (fwhm ∼ 5°). This research reveals a practical platform for simultaneously enhancing exciton emission and attenuating the substrate effect, and it provides a blueprint for the development of two-dimensional monolayer TMDs-based emitters in integrated optoelectronic devices.

Enhancing energy performance of glazing systems using solid-solid phase change materials

In recent years, the implementation of decarbonization measures in response to global warming has brought significant attention to the building sector, recognizing it as a major contributor to CO2 emissions. This study explores the unique combination of solid-solid phase change material (SSPCM) in double-glazed window (DGW) subjected to different climates, offering a novel approach to enhancing energy efficiency of glazing system, thus Building envelope. To assess the system’s energy performance, numerical simulations were performed across a range of temperature conditions. These have included extreme temperatures of the hottest and coldest days of the year, as well as different weather patterns such as sunny and cloudy days in the cities of Montreal, Vancouver, and Miami. The obtained results demonstrated that during summer sunny conditions, energy savings were achieved in both Montreal (17.5%) and Vancouver (23.5%), while Miami experienced energy losses (5.3%). On summer cloudy days, energy savings were observed exclusively in Vancouver (53.6%), whereas energy losses occurred in both Montreal (356%) and Miami (36.3%). Under winter sunny conditions, all cities showed energy losses due to the SSPCM blocking beneficial direct solar radiation during the daytime (Montreal: 18.8%, Vancouver: 3.1%, and Miami: 270%). Conversely, during winter cloudy conditions, energy savings were noted in all cities, as the SSPCM helped retain warm indoor air (Montreal: 7.0%, Vancouver: 12.4%, and Miami: 26.2%). The results revealed that complete visual transparency can be achieved during office hours, enhancing the suitability of the proposed glazing system for commercial applications. These findings can help in designing energy-efficient glazing systems subjected to various climatic conditions.

Omnidirectional to Directional Pattern Switching Patch Antenna for Wireless Sensor Nodes at Nuclear Reactor Containment Building

ABSTRACTThe novel design, prototyping, and characterization of an omnidirectional to directional radiation pattern switching planar antenna system are presented. The incorporation of the Yagi‐Uda antenna with an Alford loop antenna is proposed. The antenna is formed by a dipole, driver, reflector, and two directors. In a DC bias switching circuit with a combination of eight SMD PIN diodes and two parasitic elements, the antenna's radiation patterns can be shaped to concentrate energy in an omnidirectional radiation pattern. The introduction of switches using an SMD PIN diode at the arms of the driver element produces two switchable frequencies at 915 MHz and 2.45 GHz. Switches at the directors and reflector control the radiation pattern and can be configured to omnidirectional pattern to directional radiation pattern at those resonance frequencies. The radiation patterns as well as the simulated and measured reflection coefficients (S11) are illustrated and analyzed. Return loss (S11) is observed to be −36.36 dB at resonance frequency of 2.45 GHz (2.35–2.69 GHz) with bandwidth 340 MHz and impedance bandwidth 21.1%, and −24.45 dB at resonance frequency of 915 MHz (854–1006 MHz) with bandwidth 152 MHz and impedance bandwidth 16.61%. When compared with the omnidirectional pattern while maintaining the horizontal polarization, the gain of the antenna increases from 4.6 dBi with 90.02% efficiency to 5.1 dB with 87.77% efficiency in a directional pattern. The developed antenna system's final dimensions are 2.45 λ × 1.80 λ × 0.01 λ. The antenna system is tested in a nuclear reactor containment building equipped with a wireless sensor node. The signal transmission indicates the zero (0) invalid frames with 100 dBm received signal strength indication (RSSI). The printable nature of the antenna architecture and successful transmission of signals across the nuclear reactor containment building make the antenna a good candidate for the wireless sensor node (WSN) in the nuclear reactor.

Methodological errors in determining thermal protection of building envelopes in natural conditions

The process of thermal engineering surveys of buildings is considered. This process includes in-kind measurements of heat flux density and temperature on the surfaces of building envelope. Based on the obtained measurement results, the reduced heat-transfer resistance is calculated and compared with the required design values for building. It is shown that when calculating the heat-transfer resistance of the building envelope based on the survey results, methodological errors may occur, which are caused by external natural thermal effects on the building and internal non-stationary heat fl ows in the building envelopes. During in-kind thermal engineering surveys of enclosures of buildings of any type, these methodological errors are a priori unknown, since the measurement conditions differ from the conditions of thermal engineering tests in special climatic chambers, where a stationary difference in air temperature is maintained on the internal and external surfaces of the building envelope. To assess the methodological errors in thermal engineering surveys of buildings in natural conditions that begin on any day of the calendar year and last for several days, physical and mathematical modeling of unsteady heat transfer in the building envelope is performed. The following thermal effects, close to real ones, are taken into account during the modeling: outside air temperature; direct and diffuse solar radiation; radiant heat exchange with the environment. Enclosing structures with low and high thermal protection and thermal inertia are analyzed. Possible values methodological errors of heat engineering surveys are calculated using archived meteorological data for the Moscow region. It is shown that, depending on the season and weather conditions, their values can vary from several units to several tens of percent. The conditions for conducting surveys are determined taking into account different levels of methodological errors. A comparison of two standard methods for calculating heat transfer resistance is carried out and it is shown that the methods give different levels of methodological errors. The results obtained will be useful for specialists conducting heat engineering surveys of buildings and structures using non-destructive testing methods.

Deriving played trumpet directivity patterns from a multiple-capture transfer-function technique

The directional radiation patterns of musical instruments have long been defining characteristics known to influence their perceived qualities. Technical understanding of musical instrument directivities is essential for applications such as concert hall design, auralizations, and recording microphone placements. Nonetheless, the difficulties in measuring sound radiation from musician-played instruments at numerous locations over a sphere have severely limited their directivity measurement resolutions compared to standardized loudspeaker resolutions. This work illustrates how a carefully implemented multiple-capture transfer-function method adapts well to played musical instrument directivities and achieves compatible resolutions. Comparisons between a musician-played and artificially excited trumpet attached to a mannikin validate the approach's effectiveness. The results demonstrate the trumpet's highly directional characteristics at high frequencies and underscore the crucial effects of musician diffraction. Spherical spectral analysis reveals that standardized resolutions may only be sufficient to produce valid complex-valued directivities up to nearly 4 kHz, underscoring the need for high-resolution, played musical instrument directivity measurements.

Lyman-α feedback prevails at Cosmic Dawn: implications for the first galaxies, stars, and star clusters

ABSTRACT Radiation pressure from Lyman-$\alpha$ (Ly$\alpha$) scattering is a potentially dominant form of early stellar feedback, capable of injecting up to $\sim 100 \, \times$ more momentum into the interstellar medium (ISM) than ultraviolet continuum radiation pressure and stellar winds. Ly$\alpha$ feedback is particularly strong in dust-poor environments and is thus especially important during the formation of the first stars and galaxies. As upcoming galaxy formation simulations incorporate Ly$\alpha$ feedback, it is crucial to consider processes that can limit it to avoid placing Lambda-cold dark matter in apparent tension with recent JWST observations indicating efficient star formation at Cosmic Dawn. We study Ly$\alpha$ feedback using a novel analytical Ly$\alpha$ radiative transfer solution that includes the effects of continuum absorption, gas velocity gradients, Ly$\alpha$ destruction (e.g. by $2p \rightarrow 2s$ transitions), ISM turbulence, and atomic recoil. We verify our solution for uniform clouds using extensive Monte Carlo radiative transfer (MCRT) tests, and resolve a previous discrepancy between analytical and MCRT predictions. We then study the sensitivity of Ly$\alpha$ feedback to the aforementioned effects. While these can dampen Ly$\alpha$ feedback by a factor $\lesssim \textrm {few} \times 10$, we find it remains $\gtrsim 5 - 100 \, \times$ stronger than direct radiation pressure and therefore cannot be neglected. We provide an accurate fit for the Ly$\alpha$ force multiplier $M_{\rm F}$, suitable for implementation in subgrid models for galaxy formation simulations. Our findings highlight the critical role of Ly$\alpha$ feedback in regulating star formation at Cosmic Dawn, and underscore the necessity of incorporating it into simulations to accurately model early galaxy evolution.

CubeSat Concept for Demonstrating Efficient Directional Magnetic Radiation Protection for Spacecrafts Based on HTS Coils

CubeSat Concept for Demonstrating Efficient Directional Magnetic Radiation Protection for Spacecrafts Based on HTS Coils

Estimation of Power Production Potential From Solar Radiation and Wind Data in the Urban Area of Prishtina

For the estimation of power production from any energy resource, premeasuring is very important, where one will approximate the power production potential from the resource planned to be installed. Weather data are crucial if the chosen resources depend on the weather, such as wind and solar energy. In this paper, three weather stations are identified in three different areas inside the urban area of Prishtina City (Velania neighborhood, Technical Faculties, and Kalabria neighborhood), Kosovo. The paper aims to analyze the potential of solar and wind resources in these three locations and also identifying which of these two resources is more efficient when installed in any of the three areas mentioned above. For this study purpose, there are analyzed wind and solar data from the three locations for the years 2018–2020. The primary data taken for this research are wind velocity, wind direction, and solar radiation. The study includes the amount of electricity that can be supplied by installing solar and wind energy resources inside the urban area of Prishtina. Results of the study show that solar resources are much more suitable for installation in the urban area of Prishtina and produce much more power than wind resources, which might be used as a secondary source, to cover the power production needs during the night and part of the year when the amount of solar radiation is lower. Results also show that the use of these two renewable resources is very profitable on reducing pollution, specifically the CO2 emission.

UAV based Thermal Radiation Directionality Capture and Its Evaluation on Kernel-Driven Models

UAV based Thermal Radiation Directionality Capture and Its Evaluation on Kernel-Driven Models

Impact of Meteorological Parameters on Global Solar Radiation (GSR) at Nepalgunj Airport, Nepal

Global solar radiation (GSR), is the main source of heat that powers the energy between the geosphere and the atmosphere, is the total of the direct and diffused shortwave solar radiation that reaches the earth's surface. The target of the present report is to analyze the GSR from the data of Nepalgunj airport, Nepal in 2020. In addition, to analyze the effect of rainfall, relative humidity, maximum temperature, and minimum temperature to the GSR. The data on a horizontal surface for Nepalgunj airport, Nepal in 2020 were collected from the Department of Hydrology and Meteorology, Government of Nepal. The Angstrom-Prescott, Tiwari, and Sangeeta models were used to calculate the GSR theoretically on a horizontal surface with the help of the estimated sunshine hour. The yearly average value of GSR for the year 2020 was 18.73 MJ/m2/day. The measured GSR on a horizontal surface was found maximum in April which was 27.64 MJ/m2/day and minimum in August which was 6.38 MJ/m2/day The minimum amount of GSR found in August may be due to the high amount of rainfall of 10.51 mm in August. Talking about the seasonal variation, the Spring season receives the maximum amount of GSR i.e. 24.75 MJ/m2/day and the minimum amount is in winter i.e. 9.13 MJ/m2/day. Here, the summer season belongs to June, July, and August, and the minimum amount of solar radiation was found in August. During that month a high amount of rainfall was observed, and minimum amount of average temperature was observed. On studying the graph of variation of GSR with various meteorological parameters well-accepted relations were found. A direct relation is found between GSR and average maximum temperature, minimum temperature, rainfall, and relative humidity.

A Compact Broadband Common-Aperture Dual-Polarized Antenna for Drone Applications.

A novel common-aperture miniaturized antenna with wideband and dual-polarized characteristics is proposed, which consists of a circularly polarized (CP) and a linearly polarized (LP) antenna. The circularly polarized antenna stacked on the upper layer adopts asymmetrical ground and introduces the patch and T-type feed network. On this basis, the meshed reflector structure, which also works as a ground plane for the LP antenna, is added to reduce the influence on circular polarization and achieve directional radiation. The LP antenna stacked in the lower layer uses a monopole structure, and the coaxial feed line perforates the reflector, and thereby the common-aperture antennas are tightly stacked together from top to bottom. Simulation and test are in good accordance, and the results show that the two ports of the antenna are well matched in the range of 5.5 GHz to 7.8 GHz, where peak gains of 8.5 dB and 6 dB are realized for circular polarization and linear polarization, respectively. Moreover, the 3 dB axial ratio (AR) bandwidth of the CP antenna is 34.3% and the isolation between the two ports is better than 15 dB, suggesting potential applications in the relay platform or drone detection for signal transmission and reception.

The Anticancer Potential of Gold Nanoparticles from Flavonoid Fractions of Soursop Leaves (Annona muricata) Polymerized with PLGA on HER-2 Receptor Expression in Breast Cancer: A Literature Review

Breast cancer is a malignant disease affecting cells in the breast tissue, causing the highest mortality rate among women worldwide. As of now, the exact cause of breast cancer remains unknown, but several factors increase the risk for women, including genetics, lifestyle, direct radiation exposure, and others. In the development of breast cancer, numerous substances can influence the differentiation, adhesion, and motility of cancer cells, including the oncogene human epidermal growth factor receptor-2 (HER-2). Various treatment methods for cancer have been developed, including chemotherapy, radiotherapy, and surgery. However, due to the significant side effects and limitations of existing treatments, innovation is needed to support the success of breast cancer treatment. Recent research has explored green synthesis-based gold nanoparticles (AuNPs) as a promising alternative anticancer therapy with several advantages. The rapid growth of natural herbal plants containing anticancer compounds like flavonoids can enhance the effectiveness of modified therapies in this modern era. The polymerization of gold nanoparticles with flavonoid fractions using Poly-Lactic-co-Glycolic Acid (PLGA) can facilitate the delivery of anticancer drugs to the target site. The research method employed is a literature review using e-resources from PubMed NCBI, ScienceDirect, and Google Scholar. Keywords include Gold Nanoparticle, Breast Cancer, flavonoid, PLGA. Article criteria include full text, abstract, and publication within the last ten years (2013-2024). A total of 157 articles were obtained, and 7 articles were found to be relevant to the topic. Literature review results indicate the high anti-oncogenic effectiveness of gold nanoparticles with flavonoid-polymerized PLGA for breast cancer treatment. This finding can serve as a reference for the application of molecular therapeutic development that has proven to influence the suppression of HER-2 receptor growth expression. Keywords: Gold Nanoparticle, Breast Cancer, Flavonoid, PLGA, HER-2

Semiconductive Coordination Polymer with Multi‐Channel Charge Transfer for High‐Performance Direct X‐ray Detection

Coordination polymers (CPs) are promising for direct X‐ray detection and imaging owing to higher designability and outstanding stability, however, it remains a challenge to achieve highly X‐ray detection performance, particularly both high sensitivity and low detection limit at the same operating voltage. Herein, we construct a new conjugated CP {[Co(BPTTz)(DIPA)] DMA}n (1, BPTTz = 2,5‐bis(pyridine‐4‐yl)thiazolo[5,4‐d]thiazole, H2DIPA = 2,5‐diiodoterephthalic acid, DMA = N, N'‐dimethylacetamide), with multi‐channel charge transfer by regulating the linker mediated electronic‐state, which reduces carrier losses resulting from recombination or quenching, enhances the efficiency of charge separation and transfer, thus further optimizes X‐ray detection performance. The semiconductor prepared based on this strategy achieves record values including the highest mobility‐lifetime product (μτ, 8.05 × 10–3 cm2 V–1) and the lowest detectable X‐ray dose rate (128 nGyair S–1, 35 V) among CP‐based direct radiation detectors, as well as a high sensitivity (172 μC Gyair–1cm–2, 35 V) at the same operating voltage. This detector shows excellent long‐time air stability under ambient conditions for over three months and operational stability. These findings demonstrate a rational structural design method to enhance the photoelectronic efficiency and stability of semiconductive CPs.

Semiconductive Coordination Polymer with Multi‐Channel Charge Transfer for High‐Performance Direct X‐ray Detection

Coordination polymers (CPs) are promising for direct X‐ray detection and imaging owing to higher designability and outstanding stability, however, it remains a challenge to achieve highly X‐ray detection performance, particularly both high sensitivity and low detection limit at the same operating voltage. Herein, we construct a new conjugated CP {[Co(BPTTz)(DIPA)] DMA}n (1, BPTTz = 2,5‐bis(pyridine‐4‐yl)thiazolo[5,4‐d]thiazole, H2DIPA = 2,5‐diiodoterephthalic acid, DMA = N, N'‐dimethylacetamide), with multi‐channel charge transfer by regulating the linker mediated electronic‐state, which reduces carrier losses resulting from recombination or quenching, enhances the efficiency of charge separation and transfer, thus further optimizes X‐ray detection performance. The semiconductor prepared based on this strategy achieves record values including the highest mobility‐lifetime product (μτ, 8.05 × 10–3 cm2 V–1) and the lowest detectable X‐ray dose rate (128 nGyair S–1, 35 V) among CP‐based direct radiation detectors, as well as a high sensitivity (172 μC Gyair–1cm–2, 35 V) at the same operating voltage. This detector shows excellent long‐time air stability under ambient conditions for over three months and operational stability. These findings demonstrate a rational structural design method to enhance the photoelectronic efficiency and stability of semiconductive CPs.