Radiation Map Research Articles

FHLight: A novel method of indoor scene illumination estimation using improved loss function

In augmented reality tasks, especially in indoor scenes, achieving illumination consistency between virtual objects and real environments is a critical challenge. Currently, mainstream methods are illumination parameters regression and illumination map generation. Among these two categories of methods, few works can effectively recover both high-frequency and low-frequency illumination information within indoor scenes. In this work, we argue that effective restoration of low-frequency illumination information forms the foundation for capturing high-frequency illumination details. In this way, we propose a novel illumination estimation method called FHLight. Technically, we use a low-frequency spherical harmonic irradiance map (LFSHIM) restored by the low-frequency illumination regression network (LFIRN) as prior information to guide the high-frequency illumination generator (HFIG) to restore the illumination map. Furthermore, we suggest an improved loss function to optimize the network training procedure, ensuring that the model accurately restores both low-frequency and high-frequency illumination information within the scene. We compare FHLight with several competitive methods, and the results demonstrate significant improvements in metrics such as RMSE, si-RMSE, and Angular error. In addition, visual experiments further confirm that FHLight is capable of generating scene illumination maps with genuine frequencies, effectively resolving the illumination consistency issue between virtual objects and real scenes. The code is available at https://github.com/WA-tyro/FHLight.git.

Fast, Zero-Reference Low-Light Image Enhancement with Camera Response Model.

Low-light images are prevalent in intelligent monitoring and many other applications, with low brightness hindering further processing. Although low-light image enhancement can reduce the influence of such problems, current methods often involve a complex network structure or many iterations, which are not conducive to their efficiency. This paper proposes a Zero-Reference Camera Response Network using a camera response model to achieve efficient enhancement for arbitrary low-light images. A double-layer parameter-generating network with a streamlined structure is established to extract the exposure ratio K from the radiation map, which is obtained by inverting the input through a camera response function. Then, K is used as the parameter of a brightness transformation function for one transformation on the low-light image to realize enhancement. In addition, a contrast-preserving brightness loss and an edge-preserving smoothness loss are designed without the requirement for references from the dataset. Both can further retain some key information in the inputs to improve precision. The enhancement is simplified and can reach more than twice the speed of similar methods. Extensive experiments on several LLIE datasets and the DARK FACE face detection dataset fully demonstrate our method's advantages, both subjectively and objectively.

GIS-Based Digital Twin Model for Solar Radiation Mapping to Support Sustainable Urban Agriculture Design

GIS-Based Digital Twin Model for Solar Radiation Mapping to Support Sustainable Urban Agriculture Design

Informing solar blind radioluminescence imaging through a calibrated spectrum

While direct radiation detection methods offer great insight into the origin of ionizing particles and photons, their use to locate contaminated areas or concealed radioactive sources can lead to undue exposure of personnel and equipment to ionizing radiation or the potential for contamination. These same sources induce ultraviolet (UV) optical photon fluorescence in air – a process referred to as radioluminescence – that may be imaged from low dose regions over larger attenuation lengths than ionizing radiation. However, most optical detection methods are limited to low lighting conditions to image the more abundant ultraviolet-A (UV-A) photons. To extend this capability to room light or daytime conditions, the solar blind region (Ultraviolet-C (UV–C), <280 nm) can be tapped. Though the emission yield of UV-C photons is roughly two orders of magnitude lower than that in the UV-A regime, the UV-C offers dramatic improvements in signal-to-noise ratios under bright lighting conditions due to decreased background interferences. The yield of specific UV-C lines, if present in the literature at all, varies widely, which has a large impact in modeling and analyzing standoff UV-C measurement scenarios. Thus, we have captured improved radioluminescence spectra over 250–400 nm and identified observed emission peaks in ambient air. Many of the UV-C photons produced by ionizing radiation excitation result from high-energy, molecular nitrogen Gaydon-Herman transitions which have had limited study to date for this application. Relating these findings to published UV-A yields, we estimate emissions between 0.15 and 0.19 photons/MeV over 250–280 nm. We also use a commercial corona-discharge imaging camera to demonstrate outdoor UV-C radiation mapping of alpha and gamma emitters from 50 to 75 m standoffs, respectively. The imaged “counts” are compared to optically modeled values and show the same trend over distance.

Mapping of 10-km daily diffuse solar radiation across China from reanalysis data and a Machine-Learning method

Diffuse solar radiation (DSR) plays a critical role in renewable energy utilization and efficient agricultural production. However, there is a scarcity of high-precision, long-term, and spatially continuous datasets for DSR in the world, and particularly in China. To address this gap, a 41-year (1982–2022) daily diffuse solar radiation dataset (CHDSR) is constructed with a spatial resolution of 10 km, based on a new ensemble model that combines the clear-sky irradiance estimated by the REST2 model and a machine-learning technique using precise cloud information derived from reanalysis data. Validation against ground-based measurements indicates strong performance of the new hybrid model, with a correlation coefficient, root mean square error and mean bias error (MBE) of 0.94, 13.9 W m−2 and −0.49 W m−2, respectively. The CHDSR dataset shows good spatial and temporal continuity over the time horizon from 1982 to 2022, with a multi-year mean value of 74.51 W m−2. This dataset is now freely available on figshare to the potential benefit of any analytical work in solar energy, agriculture, climate change, etc (https://doi.org/10.6084/m9.figshare.21763223.v3).

Ionospheric responses to the tropical cyclones from different oceanic basins over the globe

The perturbations in the ionosphere due to eight tropical cyclones (TCs), namely Iota, Haima, Harold, Willa, Amphan, Gaja, Vadrah and Bulbul, originated and grown in different oceanic basins, are investigated. Total Electron Content (TEC) data, from Global Positioning System (GPS) TEC receiver in operation at Agartala (AGT) or different International GNSS Service (IGS) stations near the cyclone landfall regions, are used in this study. Despite some differences, the ionosphere responds to all tropical cyclones in an almost similar manner. Though the geomagnetic conditions are quiet and there are no perturbations due to any other geophysical phenomena in the active cyclonic storm stage, in all the cases there is a fall in average vertical total electron content (VTEC) deviations below the monthly mean value either on the landfall day or on the following day or even on just previous day. Decrements in Vertical Total Electron Content are found higher for tropical cyclones over North Indian and South Pacific oceanic basins. Recoveries in vertical total electron content values are slower for cyclones over the North Atlantic and North West Pacific basins. Recoveries in vertical total electron content (VTEC) values are slow for tropical cyclones (TCs) over the North Atlantic and North West Pacific basins. But those over other basins are quick. The longer the track of a tropical cyclone (TC), the higher is the reduction in the vertical total electron content (VTEC) value. A negative correlation exists between the maximum sustained surface wind velocities and the total periods of different TCs and also the difference of lowest average differential VTECs with that on the previous day. The observed anomaly in ionospheric responses might be due to the combined effect of TC-inspired gravity waves, ejection of neutral particles from the terminator of a tropical cyclone (TC) and lightning electric fields. To explain the observed results convective activities during TC, with the help of outgoing long wave radiation (OLR) map, are also taken into account. This study provides the primary results regarding regional characteristics and hence a comparative idea for the responses of the ionosphere to different tropical cyclones (TCs) from different geographical positions on the globe, which needs further comprehensive investigation in future.

Fractioned-pattern radiation mapping, Part II: assessment

In Part I, the authors proposed a theoretical background for predicting the radiation distribution in any optical system based on decomposing the emitting source power. Here, we describe the validity of this decomposition through a practical example that uses a radiating source and a single surface optical system. This source is calibrated in a metrology testbed that guarantees its traceability to the candela (cd), the International System (SI) base unit for luminous intensity I v . A second example, this time numerical, shows the method’s performance in a multisurface optical system.

Preliminary results of the autonomous radiation mapping in Malaysian Nuclear Agency

Autonomous radiation mapping refers to the use of autonomous robots to perform radiation mapping to measure and analyse the levels of radiation intensity of a target area. The primary purpose of the radiation mapping is to uncover the dose distribution across the target area and identify the presence of any hotspots. In this paper, the findings of the autonomous radiation mapping experiments at selected sites in Malaysian Nuclear Agency were presented. The experiments were conducted with a radiation mapping robot namely Autonomous Mobile Robot for Accurate Radiation Detection and Mapping (AMoRA) developed in the previous research. The results consisting of radiation maps of the target areas were presented and discussed.

Initial findings of autonomous radiation mapping robot field test

Radiation mapping using mobile robotic can minimize the risk of operator exposure to radiation while providing detailed radiation maps of targeted areas. Despite its potential advantages, the use of this technology is still limited and requires further investigation. In a previous study, an autonomous radiation mapping robot was designed and developed. This paper presents the initial findings on autonomous radiation mapping field test that focuses on the operation procedures and the challenges faced during the robot deployment. Temporary solutions implemented to overcome the challenges are also discussed. The results will provide insights for future researchers and operators working on mobile robotic technology for radiation mapping.

Isodose mapping of terrestrial gamma radiation in Sarawak-Borneo: Insights from surface-weathered soil analysis

Presentation of baseline data on terrestrial gamma radiation (TGR) levels is crucial for assessing the annual effective dose received by the public due to natural radiation exposure. Cumulative doses from various sources can become significant, warranting a spatial understanding of TGR distribution. Few countries have comprehensively mapped TGR on a national scale, often facing challenges due to remote or inaccessible regions. This study investigated the influence of weathered soil groups on TGR dose rates in Sarawak-Borneo, Malaysia, to facilitate insights for TGR projection and isodose mapping. A total of 1044 TGR dose rate measurements were collected using NaI (Tl) scintillation detector survey meters, with a mean of 100 nGy h−1 and a range of 8–375 nGy h−1. Non-parametric statistical analyses of variance using Welch's ANOVA, Brown-Forsythe, and Kruskal-Wallis validated (P-sig.=.000) notable dissimilarities among six categories of superficial-weathered soil. Graphical analysis using Sinclair's cumulative plot revealed deviations at intervals of 50, 80, 100, 120, 175, and 205 nGy h−1. These deviations indicate distinct lithological influences. Skeletal soil (entisols) and podzolic soils had high mean dose rates (148 and 113 nGy h−1, respectively) due to limited development, thus preserving abundant uranium (U) and thorium (Th). Meanwhile, gleysols and thionic soils exhibited compatible means (90 and 82 nGy h−1, respectively), while alluvial (or transported soils) and organic soils displayed lower dose rate ranges (mean of 76 and 47 nGy h−1, respectively), reflecting rapid hydrolysis weathering processes. Simple linear regression analysis revealed a strong relationship between TGR dose rate and mean value of weathered soil groups (y = 0.851x + 0.141 nGy h−1), signifying the significance and magnitude of weathered soil groups' impact on TGR dose rates. The obtained R-value is 0.704, indicating a strong linear correlation among soil group variables, and a Durbin-Watson statistic of 1.41, suggesting positive autocorrelation among residuals, thus positive relationships. An isodose map was successfully developed using the Kriging technique, aligning with lithological features of the study area. Semivariogram analysis reveals spatial dependence within a range of 1.47°, supporting the Kriging technique's suitability for spatial inference. In conclusion, this study has successfully revealed the relationship between TGR dose rates and superficial-weathered soil in Sarawak-Borneo. While the linear relationship is applicable to the Sundaland-Borneo tectonic block, it has potential to be used as a valuable tool for spatial inference of TGR dose rates in isodose development with similar lithologial characteristics, aiding in radiation exposure assessment and environmental monitoring.

Tetris-inspired detector with neural network for radiation mapping

Radiation mapping has attracted widespread research attention and increased public concerns on environmental monitoring. Regarding materials and their configurations, radiation detectors have been developed to identify the position and strength of the radioactive sources. However, due to the complex mechanisms of radiation-matter interaction and data limitation, high-performance and low-cost radiation mapping is still challenging. Here, we present a radiation mapping framework using Tetris-inspired detector pixels. Applying inter-pixel padding for enhancing contrast between pixels and neural networks trained with Monte Carlo (MC) simulation data, a detector with as few as four pixels can achieve high-resolution directional prediction. A moving detector with Maximum a Posteriori (MAP) further achieved radiation position localization. Field testing with a simple detector has verified the capability of the MAP method for source localization. Our framework offers an avenue for high-quality radiation mapping with simple detector configurations and is anticipated to be deployed for real-world radiation detection.

3D Radiation Mapping Using Gaussian Process Regression with Intensity Projection

This article presents a novel approach for generating a three‐dimensional radiation map using data collected by mobile robots, aimed at monitoring radiation distribution in environments such as nuclear power plants. The proposed approach leverages Gaussian process regression with a novel adaptation of the inverse square law as a kernel function, which accurately reflects the physical characteristics of radiation, enabling precise mapping from uncertain data. Additionally, a method is proposed for constructing a comprehensive radiation map in 3D environments by estimating the radiation source and project the radiation data from sparse data. The effectiveness of the methodology is validated through simulations and experiments. Utilizing Octomap, a 3D spatial mapping tool, the study not only successfully visualizes radiation distribution in complex settings with multiple sources but also quantitatively demonstrates the enhanced accuracy of our approach compared to other existing methods. This research offers contributions in managing radiation risks, providing essential insights into the field.

Mapping the Spatial Distribution of Natural Gamma Dose Rates as a Baseline Study in the Province of Asti, Italy

Natural background gamma rays and their effects on human health are essential components of both radiation protection and public concern. In the frame of these aspects, the mapping of the natural gamma dose rate values of the Province of Asti is given. The Asti Fire Brigade Command approved a project relating to the mapping of gamma radiation from the natural background in the territory of Asti. The project engaged both the Nuclear, Biological, Chemical, and Radiological (NBCR) and Topography Applied to Rescue (TAS) components of the Asti Command. Skilled personnel, comprising level 1 TAS operators for data collection and level 2 TAS operators for cartographic analysis, were deployed across the six working days. The methodology involved the use of two digital handheld radiation G-M detectors, in conjunction with a portable GPS unit, including the Global Mapper software. One of the significant findings of this study is the observation that the natural gamma dose rate levels were 201.25% higher in the streets of the city center compared to other areas, predominantly because the building materials in these locations contain a higher amount of natural radionuclides. The results indicated that the level of natural gamma dose rates in the studied region is close to the global average value.

Comparative Study of Radiation Mapping Technologies for Nuclear Disaster Assessment

The distribution of the ambient dose equivalent rate (i.e., air dose rate) after a nuclear disaster is crucial for zoning contaminated areas to facilitate authorities’ effective decision making. Several countries are considering a gradual characterization strategy where airborne measurement is performed first followed by ground measurement (i.e., via manborne or carborne surveys). Nonetheless, potential differences might emerge in country-specific air dose rate assessment methods. Explaining these discrepancies can improve and converge existing methodologies. The Japan Atomic Energy Agency (JAEA) and the French Institute for Radiological Protection and Nuclear Safety (IRSN), which are organizations involved in post-nuclear accident crisis management, jointly performed air dose rate measurements in 2019 at contaminated sites around the Fukushima Daiichi Nuclear Power Station. The similarities and differences between the two organizations’ methods and results were quantitatively assessed by comparing the average air dose rates obtained within a grid created with a geographic information system, and the reasons for the differences between the organizations’ results were investigated. The air dose rates obtained by the manborne measurements varied depending on the calibration method. Comparing the air dose rate assessment methods and mapping techniques used in different countries will contribute to developing international guidelines for recommending the best method for determining air dose rates.

Total ionizing dose estimation of ITER upper port remote handling equipment

This study delineates a comprehensive estimation of the integrated Total Ionizing Dose (TID) for the ITER Upper Port Remote Handling Equipment (UPRHE). The primary objective is to assess the radiation impact and devise strategies to attenuate its effects on the UPRHE components. Radiation levels in various operational zones are deduced from the ITER radiation map. This analysis includes a meticulous definition of operation sequences and corresponding durations for each maintenance task executed by the UPRHE. It is imperative to evaluate each subsystem of the UPRHE for its resilience against the maximum conceivable dose rate and the cumulative TID throughout its operational lifespan. The estimation of TID for the UPRHE encompasses both hourly rates and cumulative doses, calculated based on the identified dose levels and task durations. Additionally, this study computes the TID for all UPRHE subsystems over both a single long-term maintenance (LTM) cycle and the projected 20-year lifespan. Subsequently, the study justifies the derived TID values with the established nuclear radiation alert thresholds for ITER electronics. This comparison reveals that most UPRHE components remain within the safety margin. For components surpassing these thresholds, the paper proposes mitigation strategies to refine the system design in subsequent development phases.

Framework for optimizing AR waveguide in-coupler architectures.

Waveguide displays have been shown to exhibit multiple interactions of light at the in-coupler diffractive surface, leading to light loss. Any losses at the in-coupler set a fundamental upper limit on the full-system efficiency. Furthermore, these losses vary spatially across the beam for each field, significantly decreasing the displayed image quality. We present a framework for alleviating the losses based on irradiance, efficiency, and MTF maps. We then derive and quantify the innate tradeoff between the in-coupling efficiency and the achievable modulation transfer function (MTF) characterizing image quality. Applying the framework, we show a new in-coupler architecture that mitigates the efficiency vs image quality tradeoff. In the example architecture, we demonstrate a computation speed that is 2,000 times faster than that of a commercial non-sequential ray tracer, enabling faster optimization and more thorough exploration of the parameter space. Results show that with this architecture, the in-coupling efficiency still meets the fundamental limit, while the MTF achieves the diffraction limit up to and including 30 cycles/deg, equivalent to 20/20 vision.

Jet Noise and Wing Installation Effects of Circular, Beveled and Rectangular Nozzles

AbstractWith the growth of modern turbofan engines, their integration under the wing becomes challenging and induces aerodynamic and acoustic interactions between the jet exhaust and the airframe. Jet noise reduction techniques have been widely studied over the past decades but their efficiency has still to be demonstrated once installed. The present lab-scale jet experiments at Mach 0.6 compare the noise radiated by beveled and rectangular installed nozzles to circular ones on a quarter-sphere radiation map using a microphone antenna. For all radiation angles, modified nozzles show an amplitude decrease of the jet-plate interaction tones of the noise spectra attributed to a strong coupling between the jet shear layers and the sound scattering at the plate trailing edge. Beveled nozzles achieve a noise reduction for all radiation angles with a maximum decrease up to 2 dB at receiver locations perpendicular to the plate. While rectangular nozzles show a similar behavior, a sound increase is observed for listeners parallel to the plate when the height-to-width ratio is small.

Radiation Data Analysis Tool (RaDAT)

Radiation Data Analysis Tool (RaDAT), developed under a specific task order of ITER project, was designed using Matlab and it is a GUI (Graphical User Interface)-based compact application intended to support expert and non-expert users in: (1) visualization analysis of 2D radiation maps, (2) radiation qualifications of electronic equipment and (3) Occupational Radiation Exposure (ORE) analysis.It was certified for Protection Important Activities (PIA) and authorized to be used for equipment radiation qualification activities. Its main functionalities allow: (1) to visualize quickly 2D radiation maps (.VTR/.VTK files) on different planes and positions, investigating radiation conditions in different spots of the Tokamak Complex Building (TCB); (2) to analyse automatically radiation conditions of lists of millions of equipment volumes (.STL files), providing the best and the worst radiation conditions on Excel tables; (3) to calculate the total biological dose cumulated by a worker along a specific route, passing from a workstation to another, in the TCB. Another feature implemented in RaDAT is the Flexibility Radius (FR) option, which could be applied to the volumes, extending them by this FR, in order to take into account any possible relocation in proximity of the nominal installation spot.RaDAT allows reducing the analysis time considerably. It is capable to analyse one radiation map, finding the best and the worst radiation conditions within a single volume (e.g.: an electrical enclosure) in ∼ 50 ms, using a standard office laptop, reducing the analysis time by a factor ∼1000, compared to a manual analysis approach on standard visualization tools.

How to Decarbonize Greece by Comparing Wind and PV Energy: A Land Eligibility Analysis

To achieve sustainable development, the energy transition from lignite burning to renewable energy resources for electric power generation is essential for Greece. Wind and solar energy have emerged as significant sources in this transition. Surprisingly, numerous studies have examined the potential for onshore wind based on land eligibility, while few studies on open-field photovoltaic (PV) installations have been conducted. Therefore, based on the Specific Framework for Spatial Planning and Sustainable Development for Renewable Energy Sources (SFSPSD-RES), along with insights from previous relevant studies, this work conducts a land eligibility analysis of onshore wind and open-field PV installations in Greece using the software Geospatial Land Availability for Energy Systems (GLAES 1.2.1) and ArcGIS 10.2. Additionally, through an in-depth exploration of wind and solar PV energy potential in decommissioned lignite mines integrated with wind power density (WPD) and global horizontal irradiation (GHI) maps, this study compares the suitability of wind versus solar as energy sources for the decarbonization of Greece. Overall, despite the greater spatial eligibility for onshore wind turbines compared to open-field PV power plants, the relatively lower wind energy potential and operational limitations of wind turbines lead to the study’s conclusion that solar energy (PV) is more suitable for the decarbonization of Greece.

Study and validation of a fast ray tracing method to determine density flux for symmetric solar optical systems

In this research paper, a computational program called MCMRDF-3D, is developed and validated by comparison with a reference software. MCMRDF-3D is formulated on Multi-Ray Monte Carlo Method for the determination of the distribution of solar irradiation along the receiver of any solar- concentrating system that withstand translational or rotational symmetries. This code incorporate an advantageous approach that consist in estimating the overall distribution of irradiation of a large scale solar concentrating systems on the basis of a consistent sample, then saving computation time, processor capacity and storage memory. The paper presents the new approach and applied it to determine the distribution of irradiation provided by three concentrators. We compare the processing time, the irradiation map rendering, and the size of numeric data, to those provided by a Reference software. The obtained irradiation distribution and power harvesting quantities over the receiver matches very well. We conclude that MCMRDF-3D proves to easy, fast, accurate and reliable approach for the simulation of solar concentrator system. Among other implications, this work opens a path for saving time when studying numerous symmetrical imaged and non-imaged optical systems. For future work, this time saving and flexible program will be of a significant help to envision optical errors from real behavior of optical surface in concentrating systems.