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This article studied a novel connection method between the steel wire rope and the outer shell of a cobalt-60 afterloading brachytherapy source delivery whip. The performance requirements for the connection between the steel wire rope and the shell are described by analyzing the structural characteristics and usage environment of the source whip. Multiple joint forms and process ideas are proposed and explored. After repeated testing and improvement, a set of embedded adhesive bonding connection methods is finally proposed. The small-diameter cobalt-60 afterloading radiation source whip produced by this method meets the requirements of experimental verification and clinical use, effectively solving the problem of connection between the radiation source shell and steel wire rope.

This work reports on radiochromic dosimeters for 1D UV light measurements. The dosimeter is composed of a 25% Pluronic F–127 that forms a physical gel matrix and nitro blue tetrazolium chloride (NBT) as a radiation-sensitive compound. This dosimeter was exposed to UVA, UVB and UVC radiation, and the radiochromic reactions were followed with reflectance spectrophotometry including changes in light reflectance and color coordinates in the CIELAB color system. The exposition of dosimeters to all UV radiation caused color changes from pale yellow to dark violet, and its intensity increased with increasing absorbed dose. The effects of NBT concentration and UV radiation type on the dose–response of the dosimeters were also examined. The results obtained reveal that the dosimeters are the least sensitive to irradiation with UVC and the most sensitive to irradiation with UVB (e.g., dosimeter with 2 g/dm3 of NBT was characterized by the following parameters: the threshold dose 0.1 J/cm2; the dose sensitivity −5.97 ± 0.69 cm2/J; the linear dose range 0.1–2.5 J/cm2; the dynamic dose range was equal to 0.1–3 J/cm2). The results obtained reveal that the NBT–Pluronic F–127 dosimeters can be potentially useful as 1D sensors for artificial UV radiation sources measurements.

Nuclear power plant workers can be exposed to radiation under various working conditions, such as during normal operation, maintenance period, and emergency. To establish an optimal work plan, radiation dose prediction and assessment must be conducted in advance. Radioactivity data are essential to assess radiation dose. However, in some situations, these data may not be available, and analyzing precise activity of radiation source in all nuclear power plant work environments may require significant time and financial resource. Therefore, an algorithm is needed that can swiftly estimate the radioactivity of the radiation sources utilizing the radiation dose rate which are readily available data. The objective of this study is to develop an algorithm for estimating the radioactivity of arbitrary geometry radiation sources within the nuclear power plant workspaces. To achieve this, an algorithm was initially developed to estimate the radioactivity of point sources and arbitrary geometry radiation sources. Subsequently, scenarios for the point sources and cylindrical volume sources were established, and the effectiveness of the algorithm was validated with applying these scenarios. In the radioactivity estimation algorithm for the point sources, the radioactivity was estimated by reverse-calculating the external exposure dose assessment equation from the radiation dose rate data. However, various uncertainties may exist in the radiation dose rate data. Because limitations exist in deriving an exact activity value, a numerical analysis method was employed to obtain an optimal solution. The estimation procedure was divided into five steps: (1) obtaining input parameters, (2) establishing the simultaneous equation, (3) deriving an initial solution set, (4) deriving the approximate solution set, and (5) calculating uncertainty and determining the optimal solution. Additionally, a radioactivity estimation algorithm for arbitrary geometry radiation sources was developed integrating the point source radioactivity estimation algorithm and the point-kernel method. The estimation procedure was divided into two steps: (1) point segmentation of the arbitrary geometry radiation source and (2) estimation of radioactivity for the segmented point source. In the validation results of each algorithm, the error ratio between the actual and the estimated values ranged from approximately 1.19% to 11.2%. The results of this study are expected to be utilized in future for optimizing work plans in nuclear power plant workspaces where radioactivity information is unavailable.

In this study, we construct a system that autonomously and efficiently generates an exploration path that enables the estimation of the distribution of multiple radiation sources, even when the source intensities are unknown. Although the gamma ray detector cannot directly measure the distance to a radiation source, we estimate this distance by analyzing the rate of change in the number of incident gamma rays and use this to localize the source. By employing this parameter, it becomes possible to accurately estimate the distance between the detector and source, thereby significantly reducing the exploration time required for localization. Additionally, we develop a method for path planning and source localization even when multiple radiation sources are distributed across an area. We verify the validity of the proposed method through simulation experiments.

Lightning channel morphology depends on the thunderstorm cloud charge structure, which in turn is influenced by the thunderstorm dynamics. In this paper, based on three‐dimensional radiation source localization data from the Lightning Mapping Array and radar‐based data, our analysis shows that the overall morphology and detailed morphology of the lightning channel correspond to different eddy dissipation rate (EDR) characteristics. Lightning with complex channel morphology occurs in regions with large EDRs. In single lightning events, channels that extend directly within a certain height range without significant bifurcation and turning tend to propagate in the direction of decreasing EDRs, while channel bifurcations and turns usually occur in regions with large radial velocity gradients and large EDRs. This study shows the relationship between channel morphology and thunderstorm dynamics and provides a new method for the direct application of channel‐level localization data to understand thunderstorm dynamics characteristics. Plain Language Summary Turbulence in thunderstorms affects the charge distribution, which in turn affects the lightning channel morphology. Thus, the lightning channel morphology can reflect the characteristics of turbulence. The current understanding of the correlation between the two is still limited to the relationship between macroscopic thunderstorm dynamic characteristics and lightning activity. In this paper, the relationship between the morphology of the lightning channel and turbulence characteristics is investigated based on the Lightning Mapping Array (LMA) localization data and the cube root of the eddy dissipation rate (EDR) estimated from KABX radar‐based data. The turbulence strength affects the overall morphology of lightning, and lightning with complex morphology tends to occur in regions with large EDRs. In single lightning events, channels extending directly within a certain altitude range tend to propagate in the direction of decreasing EDRs, and lightning channel bifurcation or turning tends to occur in regions with large EDRs. This paper establishes the relationship between thunderstorm electricity and thunderstorm dynamics by using lightning channel morphology as a bridge and provides a new method for the direct application of channel‐level localization data to understand thunderstorm dynamics characteristics. Key Points The morphology of lightning channels can reflect the distribution of turbulence intensity, and a certain correlation between the two exist Directly extended lightning channels tend to propagate in the direction of decreasing eddy dissipation rates The location of the channel bifurcations or turns often corresponds to regions with high eddy dissipation rates

This study aims to investigate the radiological hazard and possible impact of household waste landfills on adjacent ecosystems (four landfills within the Western Forest-Steppe). Radiation background measurements were made for the first time for the selected landfills, soil samples were taken in the 5-10 cm and 10-20 cm horizons and plant samples were collected, and further examined for radioactivity ( 40 K - natural, 137 Cs and 90 Sr - artificial radionuclides). The research results revealed a prevailing dynamics of specific mass activity of radionuclides near the waste sites compared to the indicators in the control areas (mainly forest). The situation at the Dunaivtsi landfill is different, since most indicators are lower than background, especially 40 K. On the territory adjacent to the Khmelnytskyi landfill, the specific mass activity of 137 Cs is higher than the background value, while 90 Sr and 40 K values fluctuate. The study of plant samples showed a significant excess of 137 Cs and 90 Sr, but significantly lower values of 40 K compared to the control site. The radiation background values are higher than the control value. It has been established that there is no significant radioactive load on ecosystems bordering household waste landfills, but the ionizing capacity and cumulative effect of exposure to ionizing radiation sources, the ability to vertical and horizontal migration, their long-term impact on public health, the existence of living beings, ecosystems and the modifications they can cause should be considered.

The aspects of metrological assurance for the measurement of spectral characteristics of radiation receivers across a broad spectral range (from ultraviolet to infrared, including terahertz) are discussed. To date, no metrological support for measuring spectral sensitivity of radiation receivers with wavelengths exceeding 14 µm has been established, which prevented the use of these receivers for measuring terahertz radiation power in applications related to medicine, security, and climatology. To reproduce and transfer the unit of spectral sensitivity of radiation receivers in the wavelength range of 14–300 µm, traceable to an absolute cryogenic radiometer, a standard terahertz radiation receiver has been developed, manufactured, and studied. The principle of operation and the design of the developed receiver are described, and its metrological characteristics are examined. The components of uncertainty in the reproduction of the unit of spectral sensitivity of the standard terahertz radiation receiver are calculated. A budget of uncertainties during the reproduction of the unit of spectral sensitivity in the wavelength range of 14–300 µm is presented. A setup based on a monochromatic terahertz radiation source and the standard terahertz radiation receiver has been developed. This setup is intended for transferring the unit of spectral sensitivity to terahertz radiation receivers. The results of this study are of significant importance for various fields of science and technology, as measurements of spectral sensitivity are widely applied in astrophysics, lighting engineering, geophysics, biophysics, biology, medicine, agriculture, chemistry, metallurgy, etc.

It is a challenge for automatic modulation recognition (AMR) methods for radiation source signals to work in environments with low signal-to-noise ratios (SNRs). This paper proposes a modulation feature extraction method based on data rearrangement and the 2D fast Fourier transform (FFT) (DR2D), and a DenseNet feature extraction network with early fusion is constructed to recognize the extracted modulation features. First, the input signal is preprocessed by DR2D to obtain three types of joint frequency feature bins with multiple time scales. Second, the feature fusion operation is performed on the inputs of the different layers of the proposed network. Finally, feature recognition is completed in the subsequent layers. The theoretical analysis and simulation results show that DR2D is a fast and robust preprocessing method for extracting the features of modulated radiation source signals with less computational complexity. The proposed DenseNet feature extraction network with early fusion can identify the extracted modulation features with less spatial complexity than other types of convolutional neural networks (CNNs) and performs well in low-SNR environments.

In this paper, both fundamental SSP modes on a roofed metallic grating and its effective excitation of the bounded SSP mode by an injected electron beam on the structure are numerically examined and investigated in the THz regime. Apart from the bounded SSP mode on the metallic grating with open space, the introduced roofed metallic grating can generate a closed waveguide mode that occupies the dispersion region outside the light line. The closed waveguide mode shifts gradually to a higher frequency band with a decreased gap size, while the bounded SSP mode line becomes lower. The effective excitation of the bounded SSP mode on this roofed metallic grating is also implemented and studied by using a particle-in-cell simulation studio. The output SSP power spectrums with various gap sizes by the same electron beam on this roofed metallic grating are obtained and analyzed. The simulation results reveal that the generated SSP spectra show a slight red shift with a decreased gap size. This work on the excitation of the SSP mode using an electron beam can benefit the development of high-power compact THz radiation sources by utilizing the strong near-field confinement of SSPs on metallic gratings.

This study addresses the challenges of high-power consumption and complexity in conventional infrared (IR) gas sensors by integrating metamaterials and gold coatings into IR radiation sources to reduce radiation loss. In addition, emitter design optimization and material selection were employed to minimize conduction loss. Our metasurface exhibited superior performance, achieving a narrower full width at half maximum at 4197 and 3950 nm, resulting in more confined emission spectral ranges. This focused emission reduced energy waste at unnecessary wavelengths, improving efficiency compared to traditional blackbody emitters. At 300 °C, the device consumed only 6.8 mW, while maintaining temperature uniformity and a fast response time. This enhancement is promising for the operation of such sensors in IoT networks with ultra-low power consumption and at suitably low costs for widespread demands in high-technology farming.