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Alpha energy spectrum measurement has been employed in the nuclear waste disposal of transuranic nuclides (such as 239Pu and 241Am), supervision, and disposal process. The alpha spectrum is made up of alpha particles, which have a fast-moving helium nucleus and an energy of 4–8 MeV with weak penetration ability. Removing alpha particles from radioactive nuclides is an important scientific issue. In this study, a transuranic nuclide alpha particle pulse generator that produces simulated alpha particle pulses similar to real particles was designed. Field programmable gate array (FPGA) was adopted as its core chip and we obtained the digital pulse waveform using software tracing points while simulating real alpha particles by random numbers. Accordingly, the alpha energy spectrum of a radioactive source 241Am was obtained using a passivated ion-implanted planar silicon (PIPS) detector. Afterward, the alpha particle was extracted from the energy spectrum and was then compared to the alpha particle pulse of the two methods, deriving a result. Here, both groupings of particle pulse waveforms were found to be very similar, and the periodic error of the particle was observed to be less than 1%. Furthermore, the amplitude and time interval of the particle were apparently similar to the actual spectrometry pulse. [ABSTRACT FROM AUTHOR]

First arrival picking is a key factor which affects the precision of microseismic data analysis. Here, we propose a new method, which employs the maximum eigenvalue to constraint the Maeda-Akaike Information Criterion (Maeda-AIC) algorithm. First, aims at addressing the pick result affected by signal-to-noise ratio (SNR) of microseismic data, maximum eigenvalue method based on polarization analysis is applied, and the maximum eigenvalue is calculated firstly, as for three component (3C) microseismic data, the maximum eigenvalue is calculated with corresponding covariance matrix, a time window need to be set in the process of building the covariance matrix, and it is the only time window set in the method proposed in this paper, so the method is called single window Maeda-AIC (SWM-AIC), to the single component (1C) microseismic data, the variance of the data is taken as the maximum eigenvalue. Then, to reduce the effect of time window and increase the automation of the algorithm, Maeda-AIC method which is a non-window-based first arrival picking method is applied. Maeda-AIC values in preliminary window are calculated, and the preliminary window is the sequence before the largest eigenvalue of the 3C or 1C data. We validate the developed method with both synthetic and field microseismic data, using a range of signal-to-noise ratios. The developed method is compared with some basic methods, specifically STA/LTA, Maeda-AIC, and the maximum eigenvalue method. The results demonstrate that the new method is much better at identifying first arrival times than basic methods when the data have a low signal-to-noise ratio, and is even faster than the STA/LTA method with 1C data. In contrast to other improved methods, threshold value is not required for this method, and the only time window used in this method is just for maximum eigenvalue calculation, through test in the paper, its length has almost no effect on the first arrival picking. [ABSTRACT FROM AUTHOR]

Abstract Tomographic gamma scanning (TGS) is one of the most advanced non-destructive techniques for assaying the radioactive waste drum. When traditional algorithms are adopted to accurately reconstruct TGS images, the measurement data must be completely sampled by TGS system, which inevitably leads to a long-term assay. In order to save time, small number of data is measured by dividing the drum into several large voxels, which leads to inaccurate TGS images. In this work, an improved algebraic reconstruction technique (IART) is proposed to reconstruct TGS images. The total variation minimization method and the self-adaptive relaxation factor are applied to improve the iterative process of traditional algebraic reconstruction technique (ART). Experimental results show that this IART algorithm can accurately reconstruct TGS images simply based on small amount of measurement data. Compared with traditional technique, this method can reduce the mean square error and improve the signal-to-noise ratio of transmission images. And it can improve the positioning accuracy of radioisotope and the accuracy of reconstructed activity. [ABSTRACT FROM AUTHOR]

Segmented gamma scanning (SGS) is a fast and effective method for measuring radioactive waste drum. The efficiency calibration is directly related to the accuracy of reconstructed radioactivity. An efficiency function model and SGS efficiency calibration method are proposed for solving existing SGS efficiency calibration problems such as time lag, limited by experimental sources or difficult to effectively combine with SGS system. The SGS system model is established by the Geant4 to calculate the segment efficiency under different linear attenuation coefficients of medium and gamma energies. The efficiency calibration function is established with the function model and parameters. Waste drum samples are constructed with the polyethylene and point sources 137Cs/60Co to complete SGS experimental measurement, efficiency calibration and radioactivity reconstruction. The result shows that the relative deviation of the reconstructed activity of a single point source at different locations in the drum is −50.48% to 43.69% and it of multi-point sources in a segment or a drum is −27.88% to 3.57%. Experimental results verify the effectiveness of this efficiency function model and SGS calibration method. • An efficiency function model is proposed for the SGS efficiency calibration. • The relative deviation of reconstructed activity is −50.48% to 43.69% for a single point source placed in the drum. • This method can conveniently and quickly calculate the SGS efficiency. [ABSTRACT FROM AUTHOR]

A step-approximation, statistics-sensitive nonlinear iterative peak-clipping background elimination algorithm with a clipping window adaptive to the full width at half-maximum is proposed. The calibration of the full width at half maximum was expressed as a square root of a quadratic function of energy. The relative differences of the background areas under a peak in successive iteration steps were used as the condition to end the iteration. The background area under a peak is calculated as a weighted sum of the background under the peak and the background in the immediate vicinity of the peak, obtained by the clipping method. The weights are given by the background under the peak and the number of counts in the original spectrum. The proposed algorithm was applied in 152 Eu and 137 Cs gamma spectra measured with a high-purity-germanium spectrometer. After background subtraction, the net peak area can be obtained from the net spectrum. It can be universally used for the gamma spectra given by a fixed detector, as long as the full width at half-maximum has been calibrated. [ABSTRACT FROM AUTHOR]

An algorithm based on moment estimation is presented to determine the initial parameters of the particle spectrum peak shape function for the iteration fitting procedure. The algorithm calculates the mean value, variance, and third-order central moment by using the spectrum peak data, solves the parameters of the fitting function, and then provides them as the initial values to the Levenberg–Marquardt algorithm to ensure convergence and optimized fitting. The effectiveness of the proposed algorithm was tested by gamma and alpha spectra. The algorithm can be used in automated peak curve fitting and spectral analysis. [ABSTRACT FROM AUTHOR]

An improved lossless group compression algorithm is proposed for decreasing the size of SEG-Y files to relieve the enormous burden associated with the transmission and storage of large amounts of seismic exploration data. Because each data point is represented by 4 bytes in SEG-Y files, the file is broken down into 4 subgroups, and the Gini coefficient is employed to analyze the distribution of the overall data and each of the 4 data subgroups within the range [0,255]. The results show that each subgroup comprises characteristic frequency distributions suited to distinct compression algorithms. Therefore, the data of each subgroup was compressed using its best suited algorithm. After comparing the compression ratios obtained for each data subgroup using different algorithms, the Lempel-Ziv-Markov chain algorithm (LZMA) was selected for the compression of the first two subgroups and the Deflate algorithm for the latter two subgroups. The compression ratios and decompression times obtained with the improved algorithm were compared with those obtained with commonly employed compression algorithms for SEG-Y files with different sizes. The experimental results show that the improved algorithm provides a compression ratio of 75–80%, which is more effective than compression algorithms presently applied to SEG-Y files. In addition, the proposed algorithm is applied to the miniSEED format used in natural earthquake monitoring, and the results compared with those obtained using the Steim2 compression algorithm, the results again show that the proposed algorithm provides better data compression. [ABSTRACT FROM AUTHOR]

An improved threshold shift-invariant wavelet transform de-noising algorithm for high-resolution gamma-ray spectroscopy is proposed to optimize the threshold function of wavelet transforms and reduce signal resulting from pseudo-Gibbs artificial fluctuations. This algorithm was applied to a segmented gamma scanning system with large samples in which high continuum levels caused by Compton scattering are routinely encountered. De-noising data from the gamma ray spectrum measured by segmented gamma scanning system with improved, shift-invariant and traditional wavelet transform algorithms were all evaluated. The improved wavelet transform method generated significantly enhanced performance of the figure of merit, the root mean square error, the peak area, and the sample attenuation correction in the segmented gamma scanning system assays. We also found that the gamma energy spectrum can be viewed as a low frequency signal as well as high frequency noise superposition by the spectrum analysis. Moreover, a smoothed spectrum can be appropriate for straightforward automated quantitative analysis. [ABSTRACT FROM AUTHOR]

Quality identification of multi-component mixtures is essential for production process control. Artificial sensory evaluation is a conventional quality evaluation method of multi-component mixture, which is easily affected by human subjective factors, and its results are inaccurate and unstable. This study developed a near-infrared (NIR) spectral characteristic extraction method based on a three-dimensional analysis space and establishes a high-accuracy qualitative identification model. First, the Norris derivative filtering algorithm was used in the pre-processing of the NIR spectrum to obtain a smooth main absorption peak. Then, the third-order tensor robust principal component analysis (TRPCA) algorithm was used for characteristic extraction, which effectively reduced the dimensionality of the raw NIR spectral data. Finally, on this basis, a qualitative identification model based on support vector machines (SVM) was constructed, and the classification accuracy reached 98.94%. Therefore, it is possible to develop a non-destructive, rapid qualitative detection system based on NIR spectroscopy to mine the subtle differences between classes and to use low-dimensional characteristic wavebands to detect the quality of complex multi-component mixtures. This method can be a key component of automatic quality control in the production of multi-component products. [ABSTRACT FROM AUTHOR]

Clustering analysis is a promising data-driven method for analyzing functional magnetic resonance imaging (fMRI) time series data. The huge computational load, however, creates practical difficulties for this technique. We present a novel approach, integrating principal component analysis (PCA) and supervised affinity propagation clustering (SAPC). In this method, fMRI data are initially processed by PCA to obtain a preliminary image of brain activation. SAPC is then used to detect different brain functional activation patterns. We used a supervised Silhouette index to optimize clustering quality and automatically search for the optimal parameter p in SAPC, so that the basic affinity propagation clustering is improved by applying SAPC. Four simulation studies and tests with three in vivo fMRI datasets containing data from both block-design and event-related experiments revealed that functional brain activation was effectively detected and different response patterns were distinguished using our integrated method. In addition, the improved SAPC method was superior to the k-centers clustering and hierarchical clustering methods in both block-design and event-related fMRI data, as measured by the average squared error. These results suggest that our proposed novel integrated approach will be useful for detecting brain functional activation in both block-design and event-related experimental fMRI data. [ABSTRACT FROM PUBLISHER]

In this article totally asymmetric simple exclusion process (TASEP) with constrained hopping and parallel dynamics at a junction is investigated using a mean-field approximation and Monte Carlo simulations. The constrained particle hopping probability r (r ≤ 1) at a junction may correspond to a delay caused by a driver choosing the right direction or a delay waiting for green traffic light in the real world. There are six stationary phases in the system, which can reflect free flow and congested traffic situations. Correlations at the junction point are investigated via simulations. It is observed that small r leads to stronger correlations. The theoretical results are agreement with computer simulations well. [ABSTRACT FROM AUTHOR]

A totally asymmetric simple exclusion process (TASEP) has become an essential tool in modeling and analyzing non-equilibrium systems. A wide variety of TASEP models have been developed that are motivated by real-world traffic, biological transport and by the dynamics of the process itself. This paper provides an overview of recent developments in TASEP with inhomogeneity. Some important generalizations and extensions of inhomogeneous TASEP models are reviewed, and several popular mean-field techniques used to analyze the inhomogeneous TASEP models are summarized. A comparison between similar TASEP models under different updating procedures is given. Phase separations in such disordered systems have been identified. The present status of the inhomogeneous TASEP models and areas for future investigations are also described. [ABSTRACT FROM AUTHOR]

Abstract: An online automatic Ti-grade analyzer (OATGA), consisting of a 238Pu source and a proportional counter, is designed for assuring product quality. The advantage of this system was its time-effectiveness; the entire monitoring process can be finished within approximately 5min. This system has successfully solved some key analysis issues in titanium ore concentrate production process. The results obtained by feature measurements and chemical analysis were in agreement with each other. After two-year usage of OATGA at PANGANG, southwestern China, it was proved as a reliable method for online quality control in the production process of titanium ore concentrate. [Copyright &y& Elsevier]

Mining and smelting activities are the main causes for the increasing pollution of heavy metals in soil, water body and stream sediment. An environmental geochemical investigation was carried out in and around the Panzhihua mining and smelting area to determine the extent of chemical contamination in soil and sediment. The main objective of this study was to investigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the study are. The data of heavy metal concentrations reveal that soils and sediments in the area have been slightly contaminated. Geochemical maps of I[subgeo] of each heavy metal show that the contaminated sites are located in V-Ti-magnetite sloping and smelting, gangues dam. The pollution sources of the selected elements come mainly from dusts resultant from mining activities and other three-waste-effluents. The are needs to be monitored regularly for trace metal, especially heavy metal enrichment. [ABSTRACT FROM AUTHOR]

Identifying useful microseismic events is one of the key steps in monitoring tunnel rockbursts. Here, we propose a strong noise-tolerance deep learning (SNTDL) network for the automatic classification of noisy microseismic events. The training set, validation set, and test set of the SNTDL network consist of 27989 unfiltered microseismic recordings. First, to comprehensively characterize the microseismic events, we extract ten weakly correlated features of the microseismic recordings as the input of the SNTDL network. Then, the skip connection and concatenation structure are added to this network, which can further enhances its generalization ability. Additionally, the SNTDL, AlexNet, Inception, visual geometry group, and ResNet are compared using the synthetic microseismic recordings with different signal-noise ratios. The results demonstrate that the SNTDL network has a higher accuracy and stronger noise-tolerance capability than the other approaches. Application to a dataset collected from a different construction environment confirms that the SNTDL network can still achieve an accurate classification result, which further verifies that the proposed network has a reliable generalization performance. [ABSTRACT FROM AUTHOR]

Neutrons produced by cosmic rays comprise the main factor in radiation hazards for astronauts and spacecraft during space exploration. A silicon-photomultiplier- (SiPM-) array-coupled Cs 2 LiYCl 6 : Ce 3 + (CLYC) detector was proposed to measure neutrons onboard spacecraft. Since both light-collection efficiency and thermal noise rate are proportional to a SiPM's size, it is necessary to compare CLYC's characterization when coupled with SiPM arrays of different sizes. In this paper, a 4 × 4 array and an 8 × 8 array, both of which are composed of 3 × 3-mm2 SiPM elements, were coupled to a Φ 38 mm × 38 mm cylindrical CLYC detector. The energy resolution, pulse-shape-discrimination (PSD) performance, and temperature dependence were tested with two gamma-ray sources and a neutron source. Results indicate that both energy resolution and PSD performance mainly benefit from the higher light-collection efficiency of the large array. The peak centroids of 137Cs varied by ∼ 20% in the testing temperature region from -35 °C to +55 °C. [ABSTRACT FROM AUTHOR]

Detecting transportation pipeline leakage points within chemical plants is difficult due to complex pathways, multi-dimensional survey points, and highly dynamic scenarios. However, hexapod robots' maneuverability and adaptability make it an ideal candidate for conducting surveys across different planes. The path-planning problem of hexapod robots in multi-dimensional environments is a significant challenge, especially when identifying suitable transition points and planning shorter paths to reach survey points while traversing multi-level environments. This study proposes a Particle Swarm Optimization (PSO)-guided Double Deep Q-Network (DDQN) approach, namely, the PSO-guided DDQN (PG-DDQN) algorithm, for solving this problem. The proposed algorithm incorporates the PSO algorithm to supplant the traditional random selection strategy, and the data obtained from this guided approach are subsequently employed to train the DDQN neural network. The multi-dimensional random environment is abstracted into localized maps comprising current and next level planes. Comparative experiments were performed with PG-DDQN, standard DQN, and standard DDQN to evaluate the algorithm's performance by using multiple randomly generated localized maps. After testing each iteration, each algorithm obtained the total reward values and completion times. The results demonstrate that PG-DDQN exhibited faster convergence under an equivalent iteration count. Compared with standard DQN and standard DDQN, reductions in path-planning time of at least 33.94% and 42.60%, respectively, were observed, significantly improving the robot's mobility. Finally, the PG-DDQN algorithm was integrated with sensors onto a hexapod robot, and validation was performed through Gazebo simulations and Experiment. The results show that controlling hexapod robots by applying PG-DDQN provides valuable insights for path planning to reach transportation pipeline leakage points within chemical plants. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate stabilization problem of a class of double‐wing chaotic system and its circuit implementation. On the basis of a skillful method, a single‐state controller is proposed and analyzed. Comparing with recent works, the control scheme and its circuit implementation presented in this work are very simple and skillful. The circuit realization of the chaotic system and the control scheme are provided in detail. In addition, the numerical simulation, electrical simulation, and physical experiment results are discussed and presented to verify the effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

Currently, the frequency of landslides is increasing. Scientific monitoring methods are playing an essential role in effectively reducing landslide disasters. This paper proposes a method for identifying the cracks at the trailing edge of a landslide (TEL) based on image processing technology and adopts the custom interval median comparison algorithm (IMCA) to calculate the crack motion parameters. First, we perform a series of processes on the TEL images, including image preprocessing, Otsu's algorithm processing, and Canny edge detection processing, to identify the outline of the TEL. Then, we propose using the azimuth and displacement to characterize the motion of the cracks and using the IMCA to calculate the changes before and after motion of any two groups of cracks. Finally, we design a computer program using a free and open-source widget toolkit (named QT platform) based on the calculation model that corresponds to the proposed method, and we apply the crack monitoring test to a 3D simulation model, a gravel model, a soil model, and a collapsed body of the Panzhihua Airport landslide in southwestern China. From the results, it can be assessed that the method can identify the outline of the TEL and calculate the azimuth and displacement of two crack curves before and after motion. These two parameters can describe the movement of the trailing edge cracks of the monitored landslide. Thus, this method can be used in early warning system for landslide hazards. [ABSTRACT FROM AUTHOR]

Core-shell polymer coated superparamagnetic nanoparticles are critical tools in bio-nanotechnology, in which the soft and thin polymeric coatings play a key role in their stabilization, surface functionality and biocompatibility. Standard characterization tools, such as Transmission Electron Microscopy are indispensable for the morphological characterization of the metal-containing core but they cannot clearly discriminate between core and shell components. Dynamic Light Scattering can only overestimate the shell thickness by measuring the particle hydrodynamic diameter. Here, we describe Small-Angle X-ray Scattering and Small-Angle Neutron Scattering as tools to study poly (acrylic) acid coated gamma iron oxide superparamagnetic nanoparticles dispersed in aqueous medium. Our results show that Small-Angle Scattering techniques offers in situ and sensitive measurements of the “stealth” polymer coatings which cannot be accurately detected by other techniques. The Small Angle Scattering approach presented in this work is applicable for analysis of core-shell organic/inorganic hybrid nanoparticles systems for a broad range of applications. [ABSTRACT FROM AUTHOR]

The velocity model is one of the main factors affecting the accuracy of microseismic event localization. This paper addresses the issue of the low accuracy of microseismic event localization in tunnels and, combined with active-source technology, proposes a "source–station" velocity model. The velocity model assumes that the velocity from the source to each station is different, and it can greatly improve the accuracy of the time-difference-of-arrival algorithm. At the same time, for the case of multiple active sources, the MLKNN algorithm was selected as the velocity model selection method through comparative testing. The results of numerical simulation and laboratory tests in the tunnel showed that the average location accuracy of the "source–station" velocity model was improved compared with that of the isotropic velocity and sectional velocity models, with numerical simulation experiments improving accuracy by 79.82% and 57.05% (from 13.28 m and 6.24 m to 2.68 m), and laboratory tests in the tunnel improving accuracy by 89.26% and 76.33% (from 6.61 m and 3.00 m to 0.71 m). The results of the experiments showed that the method proposed in this paper can effectively improve the location accuracy of microseismic events in tunnels. [ABSTRACT FROM AUTHOR]

For this study, ion-eroded cement was prepared from the cement required for construction of middle- and low-level radioactive waste repositories in caves. The properties for adsorption of 137Cs on cement before and after ion erosion were investigated. XRF, XRD, SEM–EDS and BET were used to analyse various cement materials. The effects of reaction time, solid–liquid ratio, initial radioactivity and different ions on adsorption were studied by static batch experiments. When the initial radioactivity was 1114.5 Bq L−1 and the solid–liquid ratio was 5 g L−1, the adsorption equilibrium time was 12 h. Adsorption of 137Cs on ion-eroded cement was more effective than that on untreated cement. The adsorption process was consistent with the pseudosecond-order kinetic model and the Freundlich isotherm model, and the process involved multilayer chemisorption. This study provides basic research data for construction of a disposal repository. [ABSTRACT FROM AUTHOR]

The adsorption behavior and mechanism of Cs+ on surrounding granite of nuclear waste repository under the groundwater environment were investigated by batch experiments and characterization methods. Results indicate that the adsorption under groundwater environment is inhibited for the presence of other ions, and the adsorbed Cs+ by crushed granite are distributed in the area where K+ is deficient, proving that Cs+ can be captured by granite through ion exchange with K+. This study can provide a key reference for the safety assessment of the repository. [ABSTRACT FROM AUTHOR]

The preparation of C30 concrete for a cavernous waste repository under construction in China and its Cs(I) adsorption performance were investigated. The mix ratio of C30 concrete was cement:sand:gravel:water = 1:1.87:3.05:0.55. Three characterization analyses showed that C30 concrete has a good crystal structure, a large specific surface area and the presence of many –OH, HCO3−, CO32−, SiO42− groups and other groups. Adsorption experiments showed that the adsorption equilibrium was reached within 4 h, and pH had little effect on adsorption; several ions (K+, Ca2+, Mg2+, Cl−, NO3−, and SO42−) inhibited adsorption. The adsorption was more in line with the pseudo-second-order kinetic model and the Langmuir isothermal model. Thermodynamic analysis indicates that adsorption is endothermic and stochastic. [ABSTRACT FROM AUTHOR]

Groundwater is the most important factor contributing to the diffusion and migration of radionuclides in the repository. In this paper, the characteristic parameters of granite in a repository are obtained from static and dynamic experiments to simulate a three-dimensional geological model of the repository with the help of a groundwater modeling system (GMS). It was shown that the longest distances of 137Cs and 60Co migrations for 500 a were 146.66 m and 145.04 m, respectively. This work could be of great significance to ensure the long-term safe operation of this type of waste repository. [ABSTRACT FROM AUTHOR]

Neutron activation analysis is a highly sensitive non-destructive testing technique with important applications in industry, geoscience, medical therapy, etc. This work designed and optimized a thermal neutron device that utilized a portable D-D neutron generator, and the Monte Carlo method with the Geant4 toolkit was applied to simulation. The objective of the optimized design is to maximize the thermal neutron flux at the output surface and increase the utilization efficiency of the neutron generator. A parameter K was defined as a measure of the device's slowing capacity for neutrons and was used to determine the optimized device geometry. The simulation considered the contribution of different types and sizes of moderators and reflectors to the thermal neutron intensity to obtain the optimal size. The shielding protection of the device was then designed. The effectiveness of shielding with different thicknesses was evaluated using three dose reference points. The results indicated that the optimized device can achieve a maximum thermal neutron flux of 1.97 × 105 n∙cm−2∙s−1 at the output surface by using high-density polyethylene (HDPE) as the moderator and nickel as the reflector. It was determined that using 45 cm of HDPE and 9 cm of lead protection in sequence along the neutron head axis would reduce the dose rate at the reference point, located 5 cm from the surface of the device, below the safety limit of 2.5 μSv/h. • Geant4 was used to optimize the design of a thermal neutron activation analysis setup based on a DD neutron generator. • A maximum thermal neutron flux of 1.97 × 105 n∙cm−2∙s−1 at the output surface. • The reference point dose rate is reduced to below the safe limit of 2.5 μSv/h. [ABSTRACT FROM AUTHOR]

Bentonite was irradiated with 60Co γ-rays at a dose rate of 10 kGy/h to achieve irradiation doses of 1, 2, 3 MGy and was characterized to evaluate its stability before and after irradiation and understand the radiation damage mechanism. The structure of the bentonite was slightly affected by high doses of irradiation, and the U(VI) adsorption capacity of the irradiated bentonite was reduced compared to that of raw bentonite. Overall, this study provides insights into the negative effects of high-dose γ-ray irradiation on the stability and adsorption capacity of bentonite, which has safety implications for the storage of radioactive waste. [ABSTRACT FROM AUTHOR]

High spatial resolution tomographic gamma scanning (TGS) reconstruction is very important for the radioassay of drummed low-level radioactive waste. High spatial resolution means that the divided voxels are finer. Due to the large size of the drum, the traditional image reconstruction method based on complete samples takes a long time to scan. To limit the scanning time of the drum, sparse sampling is required. The maximum likelihood expectation maximization (MLEM) is widely used in TGS image reconstruction from projection data, but for high spatial resolution TGS imaging, its quality is insufficient to accurately describe the media boundary and determine radioactivity. The improved MLEM algorithm based on total variation (TV) regularization, such as the MLEM- TV minimization (TVM) algorithm, has been applied to reconstruct high spatial resolution TGS images. The split Bregman algorithm can quickly solve the partial differential equations of TV regularization. In this work, the split Bregman anisotropic TV (SBATV) and the split Bregman isotropic TV (SBITV) are the first time adopted to improve the iterative process of the MLEM algorithm, which are MLEM- SBATV and MLEM- SBITV. Experimental results show that both the MLEM- SBATV algorithm and the MLEM- SBITV algorithm can accurately reconstruct high spatial resolution TGS transmission images with sparse sampling. The MLEM- SBITV algorithm performs better in reconstructing the TGS emission images from sparse sampling than the traditional MLEM, MLEM- TVM, and MLEM- SBATV algorithms, increasing radionuclide positioning and radioactivity reconstruction accuracy. [ABSTRACT FROM AUTHOR]

Presents a study that determined geochemical baseline models and assessed the contributions of trace elements from natural and anthropogenic sources in the Panzhihua mining area in China. Background on Panzhihua; Adoption of a normalization procedure to establish geochemical baselines; Analytical results and relevant parameters for trace metals in topsoil samples from the area.

An organic compound adsorbent is prepared by modifying acid-activated bentonite with cetyltrimethylammonium bromide (CTAB). The physical and chemical properties of the samples before and after modification are characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and zeta potential analysis. A batch static adsorption experiment is used to study the adsorption properties of Cs+ before and after modification. Results show that the times to reach the adsorption equilibrium of bentonite before and after modification are 12 h and 2 h, respectively, and the adsorption rates are 26% and 85%, respectively. Different types of ions have different effects on adsorption. Pseudo-first-order and pseudo-second-order kinetic simulations and adsorption isotherm simulations are carried out with the data, and the adsorption capacities of the two adsorbents for Cs+ are 4.8 mg/g and 22.6 mg/g, respectively. The calculated thermodynamic parameters show that the adsorption is endothermic and spontaneous. [ABSTRACT FROM AUTHOR]

Coded-aperture imagers typically have a smaller field-of-view (FOV) than in un-collimated gamma imaging systems. However, sources out of the fully coded field-of-view (FCFOV) can cause pseudo hotspots on the wrong side of an image reconstructed using the cross-correlation method. In this work, we propose a neural network method to identify and localize the sources within the partially coded field-of-view (PCFOV). The model was trained using Monte Carlo simulation data and evaluated with both simulation and experimental data. The results showed that the proposed model can identify and localize sources with good classification accuracy, low positioning error, and strong robustness to the statistical noise. • Sources localization within a partially coded field-of-view was investigated. • A neural network model was proposed to identify and localize sources. • The model was trained using Monte Carlo simulation data. • Both simulation and experimental results demonstrate the feasibility of the method. [ABSTRACT FROM AUTHOR]

• This paper analyzed the differences between SE and DE trapezoidal shaping algorithm in detailed. • Peak probability estimation formula based on the area of photopeak and pulse resolution time is proposed. • HPGe detector, fast SDD and NaI(Tl) detector are chosen are built, experiment results show that the probability estimation formula is suitable for system with high detection efficiency and less counting loss. Nuclear signal will pile up seriously at the condition of high counting rate when using semiconductor detectors because of its high resolution and wide output signal. In order to solve the problem. Dual-exponential trapezoidal shaping algorithm with fixed pulse width discrimination is used to eliminate partial pile-up pulses at first. Then this paper proposes characteristic peak probability estimation formula based on the calculation of characteristic peaks area and pulse shaping time. And then systems based on High Purity Germanium (HPGe) detector, high performance Silicon Drift Detector (fast SDD) and NaI(Tl) detector are chosen are built, experiment results show that the probability estimation formula is suitable for system with high detection efficiency and less counting loss. [ABSTRACT FROM AUTHOR]

Achieving efficient uranium adsorption from highly acidic wastewater is still considered challenging. Here, an inorganic-organic hybridized self-assembly material (rPFE-10) with redox activity was constructed by phytic acid (PA), ethylenediamine (EDA), and Fe(II) via a facile one-pot route, and further applied for U(VI) removal. In the static adsorption experiment, rPFE-10 achieved the maximum U(VI) adsorption capacity of 717.1 mg/g at the optimal pH of 3.5. It also performed preeminently in a highly acidic condition of pH = 1.0, with the highest adsorption capacity of 551.2 mg/g and an equilibrium time of 30 min. Moreover, rPFE-10 exhibited a pH-responsive adsorption selectivity for U(VI) and An-Ln (S (U(VI)) and S (An-Ln)), which increased to 69 % and 94 % respectively as pH decreased from 3.0 to 1.0. Additionally, the spectral analysis revealed a reconstruction mechanism induced by multiple synergistic adsorption, in which U(VI) exchange with EDA+/2+ and Fe2+/3+ and earned suitable coordination geometry and ligand environment to coordinate with PA (mainly P-OH), while partial U(VI) is reduced by Fe(II) in framework. This work not only highlights the facile strategy for enhanced U(VI) retention in highly acidic solution, but expands the potential application of supramolecular self-assembly material in treatment of nuclear wastewater. [Display omitted] • Nanoplate-shaped rPFE-10 was synthesized via simple and mild self-assembly. • Redox-activity was introduced into phytic acid-based material for enhanced adsorption to U(VI). • rPFE-10 exhibited high maximum adsorption capacity of 551.2 mg/g at pH = 1.0 and 717.1 mg/g at pH= 3.5. • The mechanism involves species exchange, coordination, and reduction. [ABSTRACT FROM AUTHOR]

A kind of amino-functionalized clay was prepared by grafting APTES from clay in the Alxa area (Inner Mongolia, China), and its application for the U(VI) removal from Alxa groundwater was studied in this work. The results indicate that the sorption strongly depended on the pH and ions. The presence of amino functional groups significantly enhances the adsorption of uranium on clay in groundwater. The sorption isotherms fitted well with the Langmuir model, whereas the sorption kinetics could be fitted by a pseudo-second-order model. These findings indicate that amino-functionalized clay can effectively adsorb U(VI) in complex groundwater samples. [ABSTRACT FROM AUTHOR]

Clock skew compensation is essential for accurate time synchronization in wireless networks. However, contemporary clock skew estimation is based on inaccurate transmission time measurement, which makes credible estimation challenging. Based on one-way broadcast synchronization, this article presents a novel maximum likelihood estimation (MLE) with an innovative implementation to minimize the clock skew estimation error caused by delay. A multiple one-way broadcast model is developed for observation and set collection, while the distribution of actual delay is discussed. A clock skew MLE based on Gaussian delay is then proposed and its Cramer–Rao lower bound provided. The developed MLE is independent of the clock offset estimation, and requires only two synchronization periods to generate an accurate estimation. Extensive experimental results indicate that the performance of the proposed MLE is better than the methods popularly used in existing time synchronization protocols. [ABSTRACT FROM AUTHOR]

Montmorillonite colloid was synthesized and characterized and the adsorption of U(VI) on colloid as a function of contact time, temperature, initial concentration of U(VI) solution, pH and foreign ions was investigated through batch experiments. The results illustrate that the adsorption reaches equilibrium quickly within 30 mins. Results showed that the absorption process is influenced by pH value, temperature and ions, among which pH value is the most significant. Adsorption percentage increases obviously at pH = 4.0–7.0, and then decreases with the increase of pH value. The competitive cations also inhibit the adsorption. pH value and ions affect the surface properties and charges of the colloid and the chemical form of nuclides. The experimental data was analyzed in detail. The maximum adsorption capacity obtained by fitting the second-order kinetic model is very close to the experimental data. The Langmuir model fits the experimental data better than Freundlich models, R2 = 0.991. The results of fitting two adsorption isotherms show that the adsorption of colloids on uranium has both physical and chemical adsorption, and is mainly monolayer adsorption. Furthermore, the adsorption process is a spontaneous endothermic reaction by calculating the thermodynamic parameters. This experiment can provide some data basis for the adsorption study of U(VI) on colloids. [ABSTRACT FROM AUTHOR]

Stable mineral colloids play a role in the mobilization of actinide contaminants in the environment. In this paper we present a method to isolate and identify colloids released from high surface area sorbents associated with a proposed clay mineral barrier in a nuclear waste repository. The mineral colloids, which have a strong tendency to remain dispersed in solution, were separated from Al 13 - or (Ce Al)-pillared clay sediment, adsorbed on glass together with hydrolyzed vanadium(IV) species and studied by a variety of techniques including grazing-incidence X-ray scattering (GIXS), small-angle X-ray scattering (SAXS), Fourier transform-infrared spectroscopy (FT-IR) and atomic force microscopy (AFM). We show that the clay platelets are dimensionally orientated in the continuous, transparent 100 nm thick film until the onset of vanadium oxides above 350 °C. Organic matter and the secondary mineral quartz limit the swelling capacity of the platelets, an indication that the stable colloids originate from a part of the native clay that could not be intercalated by aluminum cations. X-ray scattering from oriented clay films intercalated by aluminum- and mixed cerium/aluminum oxo-hydroxy cations are also investigated by the GIXS technique. Unlabelled Image • A continuous, vanadium hydroxide/clay-colloid thin film was self-assembled on glass. • Clay nanoplates dimensionally orient within the 100 nm thick film. • Platelet orientation is preserved until the onset of vanadium oxides above 350 °C. • The platelets are potentially useful for actinide/clay-colloid transport studies. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Hypothesis Nanoparticles functionalized with ligands which can on-demand and remotely be detached have recently attracted interest as stimuli-responsive materials. Research is now focused on multi-responsive systems, with applications in environmental science and biomedicine. The possibility to covalently couple two different ligands on a single nanoparticles, and to release them independently is investigated. This concept of nanoparticles functionalized with dual on-demand cleavable ligands is exploited in ground water decontamination and radionuclides separation. Efficient separation of contaminants in a single step is expected, simplifying partitioning process and decreasing generation of secondary waste by nuclear industry. Experiments Sub−10 nm Janus superparamagnetic nanoparticles are functionalized by click-chemistry (thiol and Diels-Alder) with two different Actinide-specific chelators. The reversible covalent bonds allow to detach chelators independently by either pH- or thermo-stimulation. The nanoparticles decorated with diethylenetriamine-pentaacetic acid (DTPA) and [(2-furan-2-yl-2-hydroxy-ethylcarbamoyl)-methoxy]-acetic acid (FHECMAA) are incubated with UO 2 2+ and La3+ (as substitute for Pu3+) at pH = 3 and 7 before chelator-metal complexes are released. Metal contents are measured to determine separation efficiency. Findings Chelators can be detached from Janus nanoparticles with perfect selectivity. The nanoparticles are highly efficient for extraction of metals in acidic medium and show good ability for separation of U and La at neutral pH. [ABSTRACT FROM AUTHOR]

• A method based on D-SVD for noise reduction of RDTS is proposed. • A method for determining the optimal iteration number of D-SVD is proposed. • D-SVD can greatly improve the smoothness of the temperature curve. Focusing on the problem of increasing the deviation of temperature measurement for Raman-based distributed temperature sensor (RDTS) caused by random noise, a method of applying dichotomize singular value decomposition (D-SVD) to noise reduction for RDTS is proposed, and a method for determining the number of D-SVD iterations by the result's quality coefficient (RQC) is proposed to obtain effective denoised signals, thereby reducing the deviation of temperature measurement. Experiments were carried out at 45.2 °C, 50.0 °C, 55.0 °C, and 60.0 °C. Compared with the results obtained by direct demodulation of the observed signals, the maximum deviation (MD) of the temperature obtained by D-SVD noise reduction is reduced by 1.59 °C and 2.49 °C, 1.22 °C, and 0.87 °C, respectively. The root means square error (RMSE) is reduced by 0.79, 0.95, 0.67, and 0.40, respectively. And the smoothness of the temperature curve is significantly improved. At the same time, compared with the results obtained by wavelet transform by hard threshold function (WT-Hard) method and wavelet transform by soft threshold function (WT-Soft) method, the proposed method is better in these three indicators. Therefore, the proposed method can provide an available method for improving the performance of RDTS by using data processing methods. [ABSTRACT FROM AUTHOR]

A Kalman-filter-based method is proposed to address challenges in nuclear signal processing, including pileup events and noise cancelation. The state-transition equation is established on the basis of suitable pulse shape models. By regarding the output signal of particle detectors as a measurable variable, the measurement equation is also introduced to correct dynamic processes of the state transition. A linear Kalman filter with $n$ tunnels is constructed to separate pileup events and maintain the original waveforms of pulses. In addition, two terms are defined and addressed for separation operations, namely, Availability, which is used to prepare for upcoming events, and Clearance Mechanism, which is given to remove thumbnail information from the previous events and make occupied tunnels available to subsequent nuclear events. Simulation and field experiments demonstrate that the proposed method can handle critical situations of pulse pileup and minimize count loss and dead time in the X-ray energy spectrum while maintaining the original pulse shapes. [ABSTRACT FROM AUTHOR]

The cyclotron-wave rectifier can efficiently convert microwaves into direct current in wireless power transmission. Its resonator operates in the quasi-H111 mode, where there is field non-uniformity; how this field non-uniformity will affect the energy conversion is determined. In this paper, through Computer Simulation Technology simulation, combining experiential analysis with numerical fitting obtains the field expression of the operating mode, approximately calculates the Coulomb field by using the model of a filamentary electron beam, and then through the numerical solution, analyzes the effect of the field non-uniformity on the energy conversion efficiency in both the resonator and the conversion region. The results demonstrate that when the relationship between the beam current I0 and the beam radius robr satisfies the Brillouin relationship, a lesser current density can maintain the beam shape very well and ensure a high beam-wave interaction efficiency; furthermore, in a reverse magnetic field region, when I0 ≤ 0.75Iobr, a higher energy conversion efficiency can be predicted. What is more, the conclusion is in agreement with particle-in-cell simulation. Finally, numerical computation also indicates that high beam-wave interaction efficiency requires a smaller radius of the electron beam. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hollow structure was synthesized via one-pot self-assembly without templates. • P(Cr)E-7 exhibited high maximum U(VI) adsorption of 282.8 mg/g and stability at pH = 1.0. • P(Cr)E-7 presented a pH-dependent selective adsorption for U(VI) (23 % at pH = 2.0, 60% at pH = 1.0). • The mechanism of positively charged species exchange promoted coordination adsorption is revealed. Efficient removing uranium (U(VI)) from highly acidic environment remain a great challenge for the adsorbent. Herein, a novel hollow phytic acid-based hybrid material (P(Cr)E-7) was synthesized by a mild facile one-pot self-assembly method without template choosing Cr3+, phytic acid (PA) and ethylenediamine (EDA) as the inorganic and two organic building blocks. P(Cr)E-7 was employed for U(VI) capture in highly acidic wastewater. Thanks to the flexible segment assembled from EDA and PA, and the strong affinity of PA to U(VI), the maximum adsorption capacity of P(Cr)E-7 for U(VI) reached 282.8 mg/g under the condition of pH = 1.0 in static adsorption experiment. Simultaneously, P(Cr)E-7 showed the selectivity efficiency of almost 100 % for An-Ln and pH-dependent selectivity efficiency of 60 % for U(VI) in multi-ions solution with pH = 1.0. Moreover, P(Cr)E-7 showed excellent stability in 0.1 M HNO 3 and reusability after three cycles at pH = 1.0 benefiting from stable segment from coordination of Cr(III) and PA. Additionally, the SEM, XRD, FTIR, and XPS analysis revealed the adsorption mechanism that U(VI) exchanges with positively charged EDA+/EDA2+in P(Cr)E-7 to obtain preferred coordination geometry and ligand environment and further coordinates with P-OH/P = O in PA. This study addresses the practical application of effective adsorption of uranium in highly acidic nuclear industrial wastewater and illustrated a novel material design strategy of adsorbents for uranium extraction. [ABSTRACT FROM AUTHOR]

Structure is a crucial factor to decide the selectivity and sensitivity of chemosensors. In this work, a diacylhydrazone 2a and its congeneric derivatives 2b-2d were synthesized and their applications for Al 3+ detection were investigated. Except 2d , all the other compounds exhibit notable turn-on fluorescence toward Al 3+ over 15 other metal ions and the sensitivities of 2b and 2c are even higher after modification, illustrating ortho -OH indispensability in their structures for sensing. Reversibility investigation shows that the sensors all have regeneration ability. Meanwhile, the sensor-Al 3+ systems show selective fluorescence turn-off for Cu 2+ , providing a potential platform for tandem recognition of Al 3+ and Cu 2+ . 2a as a standard, shows a 1:2 molar ratio to Al 3+ confirmed by Job’s plot, 1 H NMR spectra and mass spectra, and its detection limit for Al 3+ is 7.63 nM in ethanol. It has relevant sensitivity over pH 3-9, with the highest sensitivity at around pH 4. Apart from Al 3+ detection, anion selectivity was also explored and it shows that 2a , 2b and 2c all have selectivity toward CN − evidenced by UV-vis spectra. [ABSTRACT FROM AUTHOR]

The fluorapatite-type Ca 8 Sm 1 Na 1 (PO 4 ) 6 F 2 ceramic was successfully fabricated by hot uniaxial pressing (HUP) sintering process. The effects of sintering temperature and holding time on the relative density and Vickers hardness of the ceramic were investigated. The surface microstructure, weight loss rate and surface composition of Ca 8 Sm 1 Na 1 (PO 4 ) 6 F 2 ceramic before and after the leaching experiment were examined. The influences of leaching temperature and pH value on the chemical durability of the ceramic were also studied. The results showed that the ceramic sintered by HUP at 1100 °C for 2 h obtained the highest relative density (99.46%) and maximum Vickers hardness (3.704 GPa). The largest weight loss rate (0.578%) and the highest normalized elemental leaching rates of Sm, Ca, P, Na and F were obtained in the media (pH = 3) at 90 °C. The surface of ceramic in the media (pH = 3) appeared obvious corrosion with plenty of intergranular and intragranular pores. The small weight loss rates (0.003%–0.008%) and the low normalized elemental leaching rates of Ca (7.44 × 10 −3  g m -2  d -1 - 8.22 × 10 −4  g m -2  d -1 ) and Sm (9.11 × 10 −6  g m -2  d -1 - 1.07 × 10 −6  g m -2  d -1 ) were acquired in the media (pH = 7, 9 and 11), indicating that the Ca 8 Sm 1 Na 1 (PO 4 ) 6 F 2 ceramic possessed high chemical durability in the neutral and alkaline media at 90 °C. [ABSTRACT FROM AUTHOR]

Superparamagnetic γ -Fe 2 O 3 nanoparticles (5 nm diameter) were synthesized in water. The bare particles exhibit good colloidal stability at ∼pH 2 because of the strong electrostatic repulsion with a surface charge of +25 mV. The polyacrylic acid (PAA)-coated particles exhibit remarkable colloidal stability at ∼pH 7 with abundant free carboxyl groups as reactive sites for subsequent functionalization. In this work, we used zeta potential analysis, transmission electron microscopy, small angle X-ray scattering, and Inductively coupled plasma mass spectrometry to investigate the adsorption behavior of U (VI) on bare and coated colloidal superparamagnetic nanoparticles at pH 2 and pH 7. At pH 2, uranyl ion (UO 2 2+ ) absorbed on the surface of the bare particles with decreasing particle surface charge. This induced particle agglomeration. At pH 7, uranyl ion (UO 2 2+ ) hydrolyzed and formed plate-like particles of uranium hydroxide that were ∼50 nm in diameter. The PAA-coated iron oxide nanoparticles absorbed on the surface of these U (VI) hydroxide plates to form large aggregates that precipitate to the bottom of the dispersion. At both pH 2 and pH 7, the resulting U (VI)/nanoparticle complex can be easily collected and extracted from the aqueous environment via an external magnetic field. The results show that both bare and polymer-coated superparamagnetic γ -Fe 2 O 3 nanoparticles are potential absorbents for removing U (VI) from water. [ABSTRACT FROM AUTHOR]

The ability of bentonite and montmorillonite pillared by Al-oxide and mixed (Ln-Al)-oxides (Ln = La, Ce) to remove 239 plutonium solution species from water is comparatively investigated at pH 7 and pH 4. Small-angle scattering and neutron contrast variation with H 2 O/D 2 O mixtures is used to verify the ingress of water in the calcined products after hydrophilicity was introduced by an NH 3 -H 2 O vapor treatment. The size and shape of the (La/Ce)-Al oxo-hydroxy pillaring cations (2 nm spheres) is determined by small-angle x-ray scattering from the pillaring solutions. Not all of the oxide pillars improved Pu uptake compared with sodium montmorillonite. At neutral and acidic pH only (Ce-Al)-oxide pillared clays showed the ability to remove Pu over the concentration range studied (1.35 × 10 −8 –8 × 10 −8  mol dm −3 ) with distribution coefficient ( K D ) values >10 4 . XPS analysis of the (Ce-Al)-oxide pillared clays indicates the presence of Ce 4+ as cerium dioxide. The progressive improvement in sorption performance in the order of pillar type Al 2 O 3  < La 2 O 3 -Al 2 O 3  << CeO 2 -Al 2 O 3 reflects the increasing access of Pu solution species to the clay mineral layers by changes to the basal spacing and specific surface area, and also to the higher stability of the (Ce-Al)-oxide pillars. [ABSTRACT FROM AUTHOR]

Electrostatic interaction of charged colloids and polyelectrolytes is a useful method to assemble matter into hybrid nanostructures with numerous examples in materials science as well as in biology. However, the colloidal electrostatic interaction is rapid and uncontrolled, the strong interaction usually leads to large and irregular aggregates. Therefore, control of the electrostatic interaction in order to resulting well-defined nanostructures remains a challenge. Here we report on a general and simple method to moderate the wild electrostatic interaction. Direct mixing of stock solutions containing anionic superparamagnetic nanoparticles and widespread cationic homopolyelectrolytes at an appropriate ionic strength generates aggregates with controlled shape and morphology. The simple and versatile methodology not only efficiently moderates electrostatic interactions but also enables the corresponding growth mechanism to be revealed by light scattering and electron microscopy as aggregation occurs at much slower timescales. The present results carry important implications for both practical applications and understanding on nanoscale electrostatic interaction between colloids. [ABSTRACT FROM AUTHOR]

The aim of this study is to characterize plutonium sorption particularly Pu distribution coefficients and the influence of pH on sorption processes in saturated geological materials used as a radioactive waste repository in China. The examined geological media is from a southwestern Chinese repository and consists of soil and slates. The backfill material consists of Na-bentonite from Inner Mongolia Gaomiaozi, and will be used at the Beishan high-level waste (HLW) repository, Gansu Province. The results show that the sorption capacity of Pu by geological medium in an acidic environment is low, but significantly increases with increasing pH. [ABSTRACT FROM AUTHOR]