Distribution Of Radiation Research Articles

A revised morphing algorithm for creating future weather for building performance evaluation

Climate change is one of the greatest challenges the building industry faces. Engineers and architects require representative future weather data if they would like to see how their buildings and designs will fare under a changing climate. The most common method used to create future weather involves manipulating observations commonly known as morphing, but the most used algorithms can create implausible weather conditions due to their unbounded nature. Here, bounded morphing algorithms will be described and their effectiveness proved mathematically. The improved bounded method applies two additional conditions on the morphed distribution to the maximum and minimum values, in addition to the mean values. The benefits over the standard approach will also be illustrated considering the changes in the distribution of temperature and solar irradiation due to climate change. The improved algorithms outperform the standard morphing procedures in terms of preserving the underlying climate signal while not creating unrealistic or implausible weather conditions. This method should give engineers confidence that the generated future weather series are more robust and representative of potential future weather. Practical application: The use of future weather to inform building design is now commonplace within the industry. Reliable weather files are crucial to support and deliver strategies for decarbonisation and adaptation to climate change in the built environment and the wider industry. This article provides support for the use of revised morphing algorithms which result in improved future weather time series which can be used in building simulation. For example, when applied to the temperature, it can be used to produce more accurate representations of future temperature profiles due to climate change, and for building performance assessment, such as energy consumption and overheating. It plays an important role in producing reliable and realistic weather data for future-proof building design.

Modeling of Subwavelength Gratings: Near-Field Behavior

Subwavelength gratings have received considerable attention in the fields of photonics, optoelectronics, and image sensing. This paper presents simple analytical expressions for the near-field intensity distribution of radiation scattered by these gratings. Our proposed methodology employs a 2D point dipole model and a specialized version of perturbation theory. By validating our models via numerical techniques including boundary and finite element methods, we demonstrate their effectiveness, even for narrow slits.

Effects of partial shading on thermal stress and exergetic efficiency for a high concentrator photovoltaic

Highly concentrated photovoltaic systems can produce higher energy yields than conventional photovoltaic panels but have yet to reach widespread deployment, partly because of lower lifetime and hence cost effectiveness. One limiting factor in the lifetime is the excessive generation of thermal stress. This study takes a multi-objective approach to the calibration of a highly concentrated photovoltaic thermal hybrid system. Novelty is found by exploring the relationship and trade-off between thermal stress and exergetic efficiency. A variety of optical configurations are compared by partially shading the input aperture of the primary optics. Similarly, adjustments to the receiver are made by changing the angle of the solar cell by 45°. To minimise light spillage. The primary and secondary optic positions stay the same throughout all calibrations.By experimentally validating a COMSOL model of the concentrator photovoltaic system (including irradiance distribution) a thorough analysis is conducted. It was found that the maximum thermal stress within the solar cell in this study could drop by almost 10 % with small losses (<3.5 %) to total exergetic efficiency after only small changes to receiver position. Further investigations into other specialised concentrator photovoltaics are required to understand the range of impact on thermal stress.

Comparison of the variation of solar radiation and atmospheric parameters in Kano before, during and after covid-19 lockdown

This study compared the variation of solar radiation and atmospheric parameters in Kano, Nigeria before, during, and after the COVID-19 (2019, 2020, and 2021) lockdown. Data was obtained from the Nigeria Meteorological Center (NIMET) in Abuja and MINITAB's time series method and procedures were used to analyze the data. Results showed that Kano witnessed an increased amount of solar radiation during COVID-19 (2020) when compared with the values of solar radiation distribution observed before and after COVID-19 (2019 and 2021). Atmospheric ozone increased slightly in Kano during the period of COVID-19 when compared with the periods before and after COVID-19 in the same area. Relative humidity variations were observed to be lower before and during COVID-19 when compared with the values after COVID-19, whereas temperature and pressure variation distributions were maintained approximately within the same range in the years of study (2019, 2020, and 2021). These findings provide an insight into the effects of the COVID-19 lockdown on solar radiation and atmospheric parameters in Kano.

Neural-network-based reconstruction of spent-fuel radioactive distribution in nuclear waste cask

A passive, nondestructive measuring method based on a convolutional neural network (CNN) algorithm was proposed for the rapid identification of nuclides and the precise measurement of radionuclide distribution in solid nuclear waste. In this study, the distribution of long half-life activation products—namely, 58Co, 60Co, 51Cr, 137Cs, 152Eu, 59Fe, 54Mn, 124Sb, 65Zn, and 95Zr—in nuclear waste casks containing cement-cured spent fuel from pressurized water reactor (PWR) nuclear power plants was used as an example, and a Geant4-based “Radiation Distribution Detector Count” dataset was developed. Based on the features of distribution reconstruction, a CNN model was constructed, its parameters being modified and trained. We then evaluated the network model based on the reconstruction of the inhomogeneous distribution of radioactivity for each nuclide in the nuclear waste cask, the results proving to be acceptable for the evaluation parameters of the average relative error (ARE) and the maximum relative error (MRE). Further, a detector design optimization approach was provided for combining the reconstruction accuracy of the radioactivity distribution with the detector point arrangement.

Enhancing the effectiveness of bioaerosol disinfection in indoor environments by optimizing far-UVC lamp locations based on Markov chain model

Far-ultraviolet C (far-UVC) light is an effective and safe disinfection method for bioaerosol control in occupied indoor environments. The installation location of a far-UVC lamp strongly influences the spatial distribution of far-UVC irradiance, and thus the effectiveness of bioaerosol disinfection. To assist the design process, this study developed a fast prediction approach based on the Markov chain model for optimizing the installation locations of far-UVC lamps in order to enhance the disinfection effectiveness for indoor bioaerosol control. Experiments were conducted in an environmental chamber to validate the proposed simulation-based optimization approach. The results show that the proposed method can correctly predict the disinfection efficiency when compared with experimental data, and optimizing the installation location of the far-UVC lamp increased the disinfection efficiency by 54 % compared with the worst location. As an application, the validated method was then used to design the installation location of a far-UVC lamp in a real conference room. The results show that installing the far-UVC lamp in the optimal location can increase the disinfection efficiency by 48 % compared with the worst installation location. Therefore, optimizing the far-UVC lamp location using the proposed Markov chain model can enhance the effectiveness of bioaerosol disinfection in indoor environments.

An On-Orbit Relative Sensor Normalization for Unbalance Images from the Ice Pathfinder Satellite (BNU-1)

The Ice Pathfinder satellite (code: BNU-1) is the first Chinese microsatellite, designed for monitoring polar climate and environmental changes. The major payload of BNU-1 is the wide-field camera which provides multispectral satellite images with a 73.69 m spatial resolution and a 739 km swath width. However, the color misrepresentation issue can be observed as the BUN-1 image appears yellowish as it gets farther towards the center field of view (FOV). The blue band of the image appears to be higher near the center FOV and declines generously towards both the edge areas of the image, which may cause the color misrepresentation issue. In this study, we develop a relative sensor normalization method to reduce the radiance errors of the blue band of BNU-1 images. This method uses the radiometric probability density distribution of the BNU-1 panchromatic band as a reference, correcting the probability density distribution of the blue band radiance first. Then, the mean adjustment is used to correct the mean of the blue band radiance after probability density function (PDF) correction, obtaining the corrected radiance in the blue band. Comparisons with the ground measurements and the Landsat8 image reveal the following: (1) The radiances of snow surfaces also have good consistency with ground observations and Landsat-8 images in the red, green, and blue bands. (2) The radiance errors of the uncorrected BNU-1 images are eliminated. The RMSE decreases from 80.30 to 32.54 W/m2/μm/sr. All these results indicate that the on-orbit relative correction method proposed in this study can effectively reduce the radiance errors of the BNU-1 images.

Characteristics and variation laws of electromagnetic radiation generated during explosion

AbstractThe characteristics and laws of explosive electromagnetic radiation must be clarified to investigate its interference with electronic equipment. Currently, studies pertaining to explosive electromagnetic radiation are performed via small equivalent explosive explosion tests, and conclusions regarding the regularity of electromagnetic radiation from warhead explosions are not confirmed. This study analyzes the power laws of explosion electromagnetic radiation via numerical simulations, literature comparisons, experimental testing, and other methods. The results show that the duration of the explosion electromagnetic radiation is proportional to the 1/3 power of the equivalent. The delay time is between 44 and 53 μs and is inversely proportional to the detonation velocity. The peak time is positively correlated with the 1/2 power of the equivalent. The electric field intensity of an explosive explosion is directly proportional to the 1/3 power of the equivalent, whereas the electric field intensity of a warhead explosion is positively correlated but not linearly related with the equivalent power. The spectral distribution of the electromagnetic radiation caused by different types of explosives differ significantly. The electromagnetic radiation measurement results for explosive explosions can be predicted via numerical simulation. However, the simulation results do not match the measurement data of warhead explosions, thus highlighting the necessity of warhead explosion electromagnetic measurements.

Design, analysis and validation of Customised Homocentric Fresnel Collector based on longest wavelength of visible spectrum

The paper presents the design of a Customised Homocentric Fresnel Collector (CHFC) based on the principle of superposition and the longest wavelength of the visible spectrum. A bottom-to-top approach is proposed that uses an individually designed homocentric prism based on visible light at a wavelength of 740 nm. The homocentric prism of the CHFC follows a uniform height method with varying pitch. An area focus is achieved on the plastic optical fibre (POF) bundle inlet without employing any secondary optical element. The CHFC achieves a uniform distribution of concentrated visible spectrum radiation from the Sun with a significant reduction in the hotspot problem. Comparison of the CHFC versus a mid-wavelength-based Fresnel lens shows that the CHFC delivers 9.24% more visible spectrum radiation on the POF bundle inlet. The simulated optical efficiency of the CHFC is 90.6%. Numerical analysis of a CHFC-based daylighting system shows that 331 lm (efficiency of 39.4%) can be delivered via a 10 m long fibre bundle made up of 32 POF each of 1 mm diameter. Experimental observations demonstrated that the maximum temperature recorded on the POF bundle entrance is 56.8°C during peak direct normal illuminance conditions. Note that the spectral distribution of the radiation emerging from the POF differs from the incident sunlight spectrum because of the transmission characteristics of the optical components used in the CHFC testbed.

Design and implementation of 2 KW OFF-GRID photovoltaic systems with maximum power point tracking using PSO algorithm operating under partial shading conditions

This paper presents the design and implementation of a metaheuristic control method for maximum power point tracking (MPPT) methodology in photovoltaic systems under partial shading conditions. To attain maximum efficiency, photovoltaic (PV) panels should operate at their maximum power point (MPP). Therefore, to maximize the power from the PV system, an MPP tracker is inserted between the PV arrays and the load to ensure that the operating point of the system is adjusted to be placed on the MPP. When the radiation distribution over PV panels is uniform, many traditional MPPT techniques can effectively monitor MPP. However, when the PV arrays are partially shaded, more MPPs are displayed, which usually results in the inability to find the overall MPP. To overcome this difficulty, this proposed work presents a particle swarm optimization algorithm-based MPPT scheme for PV systems. This PSO heuristic algorithm-based technique not only ensures the ability to find the global MPP but also gives a simpler control scheme. The feasibility of this proposed method is verified by various partial shading conditions using Matlab. The proposed method is implemented with a 2KW PV system and the power output is compared with the existing system.

Radiation in a plasma and applications to cosmic microwave background

AbstractIn a recent paper [Phys. Rev. E 100, 023202 (2019)], Munirov and Fish proposed application of the well‐known approach for the calculation of the fluctuation field radiation spectrum in a transparent fully ionized plasma to the problem of cosmic microwave background. They used the result for spectral energy distribution of the equilibrium radiation, assuming that the spectrum of free photons is changed to the non‐damping spectrum of transverse waves in non‐relativistic plasma. The similar approach has been considered earlier by several authors for non‐relativistic and relativistic plasmas. The results of Munirov and Fish are in fact in perfect agreement with the most of the previously existing expressions. However, we argue that this approach based on such simple approximation is not enough justified and the more elaborated consideration, taking into account not only temporal but also spatial dispersion of dielectric permittivity is necessary for a consistent description of radiation in plasmas. Moreover, interaction between free photons and charged particles in the framework of quantum electrodynamics leads to the result different in comparison with the standard consideration even for the transparent plasma medium.

Large nonreciprocity of thermal radiation for transverse electric wave with extremely small incident angle

Violating of traditional Kirchhoff’s law has been a topic of active research because of the possibilities for engineering thermal radiation. An alternative paradigm consisting of zero-contrast gratings (ZCGs) and Weyl semimetal (WSM) interlayer sitting on a silver (Ag) substrate is proposed. Strong nonreciprocal thermal radiation (NTR) has been observed for transverse electric (TE) incidence wave. This structure is highly favorable for standard mask-based nano-fabrication processes. Moreover, the nonreciprocity larger than 0.8 is realized with an extremely small angle of 1°. The mechanism of this proposal is owing to the guided-mode resonance (GMR) supported by the ZCGs and nonreciprocal radiation of WSM, which is confirmed by investigating the amplitude distribution of electric field. The high performance of the NTR can be maintained within wide ranges of structural parameters, which is highly favorable for practical fabrication. The nonreciprocal emitter described herein allows simultaneous control of spectral distribution and polarization of radiation, which will facilitate the active design and application of mid-infrared (MIR) thermal emitters.

Assessment of the ITER divertor bolometer diagnostic performance

The ITER bolometer diagnostic will provide measurements of the total radiation emitted from the plasma, a part of the overall energy balance. It will consist of some 550 lines of sight (LOS) of bolometer detector, bundled in multiple individual cameras, which will be located in the gaps between blanket modules on the vacuum vessel wall, in five divertor cassettes, in two upper port plugs and in one equatorial port plug (Meister et al., 2017). The LOS are optimised as much as possible with design constraints to capture the details of different plasma regions in which the intensity and local distribution of radiation will vary over a large range. This is especially true in the divertor, where up to 70 % of the total thermal exhaust power from the core will have to be radiated during burning plasma operation. This radiation will be tightly concentrated meaning that not only will tomographic reconstruction of the distribution be challenging, but the bolometer cameras themselves need to be properly designed to handle the resulting heat fluxes. This paper first presents an assessment of the photonic heat fluxes falling on bolometers in the divertor region during high performance operation (where the heat fluxes will be highest). These heat fluxes are computed using ray-tracing from radiation distributions obtained with the SOLPS (plasma boundary region) and JINTRAC (plasma core region) codes and will serve as essential input to the thermal design studies of bolometers. The same SOLPS and JINTRAC simulations are used as models for the second focus of the paper which examines how closely the radiation distribution obtained from tomographic inversion of synthetic signals from the bolometer LOS matches the model input. Some effort has also been devoted to a study of how the reconstructions are affected by loss of individual LOS.

Assessment of the Applicability of PV/T Electric Heating System for the Storage of Crude Oil

There are still some doubts about whether the solar photovoltaic/thermal (PV/T) system is applicable for the practical heating system of crude oil storage although there has been a lot of research work on PV/T and heating technology in the oil field. Due to the uneven distribution of solar radiation and uncertain thermal property of crude oil, the amount of energy provided and demanded is hard to evaluate. In this study, an electric heating system based on PV/T is proposed to be applied for the storage of crude oil. By establishing the mathematical model of the system, the energy supply capacity of PV/T and the heat demand of stored crude oil in typical seasons in Xinjiang are predicted by numerical method. The applicable scheme is discussed. This study may promote the application of PV/T heating systems in oil fields.

Particles creation from JNW quantum perturbed black holesby minimally coupled Klein Gordon scalar free fields

In this work, we choose a minimal coupling interaction between massive Klein Gordon (KG) quantum scalar free fields and Janis-Newman-Winicour (JNW) spherically symmetric static black hole, to produce its Hawking temperature and luminosity. This is done by calculating asymptotic wave solutions at near and far from the black hole horizon. They are orthogonal mode solutions of local Hilbert spaces. By using these mode solutions, we calculated Bogolubov coefficients and then, we investigated number density matrix of created particles. Mathematical calculations show that this is not exactly similar to the Planck`s black body radiation energy density distribution but, it is “gray” body radiation distribution depended to the emitted Hawking particles frequency. Their difference is a non-vanishing absorptivity factor of backscattered particles after to form horizon of a collapsing body. Our motivation is determination of position of Hawking created pairs in which, two different proposals are proposed, so called as “fairwall” and “quantum atmosphere”.

Simulating the 3D Distribution of Absorbed Shortwave Radiation in a Tree Crown: Comparison of Simplified and Monte Carlo Models

AbstractUrban trees are expected to alleviate severe thermal environments in summer. The absorbed shortwave radiation is a key variable to estimate the microclimatic effects of trees. In numerical simulation tools for the urban and built thermal environment, the difficulty lies in how to calculate the absorbed radiation in terms of accuracy and computational load. Here we investigated the difference between a radiative transfer model calculating scattering by the Monte Carlo method and a simpler model that accounts for scattering by modifying the optical depth. The calculations of absorbed radiation were performed under various conditions of leaf normal distribution and zenith angle of incident radiation, using tree models represented by voxels with different leaf area density values. For the photosynthetically active radiation, the relative difference between models was less than 10% for most cases. For the near‐infrared radiation, the difference was also small for a large canopy consisting of several trees. The difference was 30%–60% and 0%–20% for zenith angles of incident radiation of 0° and 60°, respectively, for small isolated trees with a crown height and width of less than 5 m, which was a significantly different condition from a uniform canopy. This large difference was related to the uniformity of the canopy and was explained by the transmittance from each voxel to the outside of the canopy. The present study enables us to evaluate the applicability of the simple model and correct the difference from the Monte Carlo model.

Oort cloud perturbations as a source of hyperbolic Earth impactors

The observation of interstellar objects 1I/’Oumuamua and 2I/Borisov suggests the existence of a larger population of smaller projectiles that impact our planet with unbound orbits. We analyze an asteroidal grazing meteor (FH1) recorded by the Finnish Fireball Network on October 23, 2022. FH1 displayed a likely hyperbolic orbit lying on the ecliptic plane with an estimated velocity excess of ∼0.7 kms−1 at impact. FH1 may either be an interstellar object, indicating a high-strength bias in this population, or an Oort cloud object, which would reinforce migration-based solar system models. Furthermore, under the calculated uncertainties, FH1 could potentially be associated with the passage of Scholz’s binary star system. Statistical evaluation of uncertainties in the CNEOS database and study of its hyperbolic fireballs reveals an anisotropic geocentric radiant distribution and low orbital inclinations, challenging the assumption of a randomly incoming interstellar population. Orbital integrations suggest that the event on March 9, 2017 (IM2) from CNEOS may have experienced gravitational perturbation during the Scholz fly-by, contingent upon velocity overestimation within the expected range. These findings suggest that apparent interstellar meteors may, in fact, be the result of accelerated meteoroid impacts caused by close encounters with massive objects within or passing through our solar system.

Measurement and analysis on distribution of radiation field dose inside the treatment room of TaiChi Pro multimodal integrated digital radiotherapy system

ObjectiveTo examine the leakage radiation dose from the accelerator module's primary beam self-shielding, as well as stray radiation levels and distribution in the treatment room across various planes for the innovative X/γ multimodal radiotherapy system, TaiChi Pro, which is the world's first digitally integrated system that combines a linear accelerator, multi-source rotational focused gamma knife, and multi-modal image guidance, in order to formulate treatment room safety strategies and estimate additional radiation doses to patients. MethodsThe TaiChi Pro multi-mode integrated radiotherapy system was utilized with a 6 ​MV X-ray accelerator in the flatten-filter free (FFF) treatment mode. The system has a primary radiation beam self-shielding, and an isocenter dose rate of 800 ​cGy/min. For detection points in various planes, an x, y, z coordinate system was established with the isocenter as the origin. To simulate the situation of patient, water-equivalent phantom was employed. The ambient dose equivalent and ambient dose equivalent rate at detection points in the radiation field were measured using thermoluminescence dosimeters. ResultsThe self-shielding area achieved a maximum dose of 114.0 ​mGy at 1 m distance from the target point after 3 ​min of cumulative irradiation. The leakage radiation ratios at all points remained below 0.5%, fulfilling the self-shielding design requirements. Regarding the couch, the highest radiation was observed in the opposite direction of the beam at the target point. The stray radiation on the treatment bed plane resulted in an ambient dose equivalent that did not exceed 0.5% of the ambient dose equivalent at the central point. ConclusionThe levels and distribution patterns of stray and leakage radiation inside the TaiChi Pro treatment room meet the requirements of the relevant national standard. The measured values of indoor radiation levels and distribution are very useful for room shielding design and personnel protection.

Analysis of the light performance of Chinese solar greenhouse with internal insulation based on a solar radiation model

Chinese solar greenhouses are important agricultural building facilities with highly efficient and sustainable solar energy consumption. A solar greenhouse with an external insulation blanket for heat preservation is the most prevalent type of CSG. However, greenhouse performance degrades as the thermal insulation performance of the external blanket deteriorates over time when the blanket is exposed to harsh environmental conditions. Moreover, the external blanket is usually parked in an inconvenient location on the south roof in the practice, resulting in shading owing to its increasing coverage length. This significantly influences the solar radiation received by the south roof and that projected on the wall, ultimately affecting the light performance of the greenhouse. Therefore, a solar greenhouse with an innovatively applied internal insulation system was proposed in this study. To analyze the light performance of the solar greenhouse, a solar radiation model was established and verified by comparing the measured and calculated values. Based on the calculated model results, the spatial distribution of solar radiation inside the greenhouse and its allocation to the interior surfaces of the greenhouse were simulated. The total captured and transmitted solar radiation accumulations were compared for three different roof shapes. The captured and transmitted radiation accumulation of the greenhouse with internal insulation increased by 3.9–9.5 and 1.8–4.4 MJ compared to the two other greenhouses, respectively. The effect of the position of the parked blanket on the beam solar radiation projected on the wall and ground was considered. The results indicated that the increased blanket coverage length decreased the cumulative radiation on the wall by 25.24%–99.82%, which did not contribute to improving greenhouse energy-saving production. This study provides a new approach to greenhouse design and optimization.

Insights about Modelling Environmental Spatiotemporal Actions in Thermal Analysis of Concrete Dams: A Case Study

In order to conduct thermal analysis of concrete dams, it is necessary to assess and validate the spatiotemporal representations used for modeling the solar radiation and the water temperature boundary conditions. To illustrate this procedure, the thermal analysis of a concrete multiple-arch dam is presented. The article starts by providing an overview of the problem before focusing explicitly on the estimation of solar radiation distribution. Within this section, a comparison between the solar irradiance computed on the downstream face of the dam with or without considering the beam radiation shading at different times of the year is presented. This is followed by an analysis of the seasonal behavior of the water temperature of the dam’s reservoir based on measured data. After calibrating an empirical/statistical law based on temperatures measured at different depths, it is compared with the values estimated by a hydrodynamic model and some temperature profiles measured upstream of the dam. Finally, the article compares the results obtained with the thermal analysis versus the temperature measured by thermometers installed in the concrete.