Search

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]

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]

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]

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]

• 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]

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]

• 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]

[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]

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]

This study proposes a novel natural environment background model by modeling brief environment conditions. It uses Geant4 program to simulate decays of 238 U, 232 Th, and 40 K in soil and obtains compositions of different-energy gamma rays in the natural environment background. The simulated gamma spectrum of the natural environment background agrees well with the experimental spectrum, particularly above 250 keV. The model is used in the simulation of anticoincidence measurement, indicating that the natural environment background can be decreased by approximately 88%, and the Compton attenuation factor is 2.22. The simulation of anticoincidence measurement can improve the minimum detectable activity (MDA) of the detection system. [ABSTRACT FROM AUTHOR]

An innovative coordination polymer based on a tritopic ligand having the bis-terpyridine cyclam ( CHTT ) unit is explored. Homo- or heteronuclear 1D coordination polymers can be formed with bivalent metal ions such as Co(II) and Ni(II) in solvent DMF. Creep-recovery curves of the (Co II ) 2 CHTT gels formed from 1D coordination polymers were analyzed with the Burgers model and demonstrated an original self-healing property, unusual in the class of molecular gels. The influence of the metal type was studied through the structural features using small-angle neutron scattering (SANS) experiments. In gels, the corresponding network involves genuine fibers ( R ≈ 35 Å), bundles of these fibers and also a fraction of finite size aggregates (rods with aspect ratio f ≈ 3–5). We found that the distribution of these latter structural components is sensitive to the metal ions type. Such tritopic 1D coordination polymers exhibit a range of original structural features and a facile control of the developed structures in solutions and gels by tuning their thermodynamic parameters. The versatility associated to the intrinsic dynamic ability of the systems should pave the way to original properties for molecular devices. [ABSTRACT FROM AUTHOR]

The detection speed of the tomographic gamma scanning (TGS) system with a detector array is faster than the single detector system. The NaI(Tl) detector is inexpensive and can work at room temperature, making it ideal for use in the TGS system with a fan-shaped detector array. The collimator of the TGS system is one of the critical elements to ensure the reconstructed image's quality. In addition to providing good detection efficiency of the detector while improving the system's spatial resolution, a proper collimator structure may also reduce cross-interference between segments. We propose a collimator design method for the TGS system with a fan-shaped NaI(Tl) detector array and combine it with the Monte Carlo method to optimize the collimator. We get the collimator aperture size and shape of the TGS system through the simulation results. Simultaneously, according to the detectors' equiangular sector arrangement limitation, we propose setting up a fan-shaped shield with adjustable depth and height at the detector collimator's front. The cross-interference between segments is effectively reduced without reducing the current segment's detection efficiency. The transmission image reconstruction shows that the collimator designed by this method can be used in the TGS system with the fan-shaped NaI(Tl) detector array. • The collimator of the TGS system with the fan-shaped NaI(Tl) detector array is optimized with the Monte Carlo method. • The fan-shaped shield effectively reduces the cross-interference between segments. • A TGS system with a fan-shaped NaI(Tl) detector array is adopted to reconstruct transmission tomography. [ABSTRACT FROM AUTHOR]

The Alxa region (Inner Mongolia, China) is one of the areas preselected for use as a geological repository of high-level radioactive waste in China. Radioactive waste produces radioactive rays during long-term storage, and the cumulative absorbed dose in 1000 years can significantly exceed the maximum of 0.7 MGy, thereby challenging the long-term adsorption stability of clay. This study employed 60Co gamma (γ)-rays to irradiate clay in air under a dose rate of 10 kGy/h. The changes in the internal structure and mechanisms of clay under different gamma radiation doses (1, 2, and 3 MGy) were investigated. Additionally, the adsorption properties of irradiated clay for U(Ⅵ) were tested under different conditions. The clay samples underwent minimal structural changes following high-dose irradiation, and the interlayer spacing was altered due to the fractured framework, dehydroxylation, and radiolysis of water. After irradiation, the Fe (Ⅱ) content in clay was significantly increased, unlike Fe (Ⅲ) content. The adsorption mechanisms of clay before and after the experiments were verified, revealing that the adsorption capacity of irradiated clay to U(Ⅵ) is reduced. [Display omitted] • Gamma irradiation caused H 2 O radiolysis and skeleton fracture in clay samples. • The Fe (Ⅱ) content in clay significantly increased after gamma irradiation. • The uranium adsorption capacity of clay decreased after gamma irradiation. • Uranium adsorbed on clay mainly in the form of UO 2 2+. [ABSTRACT FROM AUTHOR]

A silicon photomultiplier array-coupled Cs 2 LiYCl 6 :Ce 3 + detector was developed for neutron monitoring onboard the lab module at the China Space Station. As the environmental temperature of the lab module varies, the temperature dependence of the assembled CLYC detector performance should be studied before the detector is installed. In this study, the equilibrium time for the CLYC detector to reach the set temperature in the chamber was estimated. The variabilities of the calibration coefficients and energy resolutions were measured using two gamma-ray sources and a neutron source, and the influence on pulse shape discrimination was investigated by using the charge comparison method. The results illustrated that the calibration coefficients and energy resolutions increase from -40 to +10 °C, and then decrease from +10 to +50 °C, and that the figure of merit value monotonically decreases over the investigated temperature range. These variation curves were applied to the measurement corrections. [ABSTRACT FROM AUTHOR]

Recently, clays have been investigated for the long-term storage of spent nuclear fuel and nanominerals have been developed for the separation of radionuclides from subsurface water, but the detailed structure relating to pillaring of the sorbent is not always easily assessable by X-ray diffraction, for example, where the shift of the basal spacing to a higher value is not distinct. The purpose of this study was to gain an insight into the correlation between nanoscale structure and macroscopic sorption performance. The time dependence of 239‑plutonium sorption to Laponite, (Ce Al)-Laponite, and (Ce Al)-bentonite was studied. (Ce Al)-Laponite was characterized by TEM, XPS, XRD, N 2 adsorption/desorption isotherms, and small-angle neutron scattering. Analysis of neutron scattering from dry powder and powder dispersed in water showed that (Ce Al)-Laponite has an open pore-fractal structure described by a fractal dimension D p = 2.5, and a radius of gyration R g = 6.5 nm. In a slightly alkaline pH condition, the strength of the sorption (K d) of 239Pu by the different sorbents, from most to least, was (Ce Al)-bentonite (104) > (Ce Al)-Laponite (~104) > Laponite (103) > bentonite (103). The time it took for Pu sorption to reach equilibrium for (Ce Al)-Laponite was almost two times faster than that observed for the starting clays and the (Ce Al)-bentonite (8 days). A pseudo-second order rate expression was applied to the time-course data to describe the kinetic behavior. The enhanced rate of sorption was attributed to the connected pore system present in (Ce Al)-Laponite. • 239Pu sorption to Laponite, Ce-Al-Laponite, and Ce-Al-bentonite is investigated. • Ce-Al-Laponite has an open pore-fractal structure based on various analyses. • K d 239Pu (mild alkalinity): Ce-Al-bentonite > Ce-Al-Laponite > Laponite > bentonite. • Enhanced sorption rate is ascribed to the connected pore system in Ce-Al-Laponite. [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.

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 137 Cs/ 60 Co 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., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Honglong Zheng reports financial support was provided by Key Laboratory of Higher Education of Sichuan Province for Enterprise Informationalization and Internet of Things. Honglong Zheng reports financial support was provided by National Natural Science Foundation Committee of China. Qi Liu reports financial support was provided by Sichuan Provincial Department of Science and Technology of China. Yuhao Li reports financial support was provided by University Student Innovation and Entrepreneurship Training Program of China., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

One-way-broadcast-based flooding time synchronization algorithms are commonly used in wireless-sensor networks (WSNs). However, the packet delay and clock drift pose a challenge to accuracy, as they entail serious by-hop error accumulation problems in the WSNs. To overcome this, a rapid-flooding multibroadcast time synchronization with real-time delay compensation (RDC-RMTS) is proposed in this article. By using a rapid-flooding protocol, flooding latency of the referenced time information is significantly reduced in the RDC-RMTS. In addition, a new joint clock skew-offset maximum-likelihood estimation (MLE) is developed to obtain the accurate clock parameter estimations and the real-time packet delay estimation. Moreover, an innovative implementation of the RDC-RMTS is designed with an adaptive clock offset estimation. The experimental results indicate that the RDC-RMTS can easily reduce the variable delay and significantly slow the growth of by-hop error accumulation. Thus, the proposed RDC-RMTS can achieve accurate time synchronization in large-scale complex WSNs.

The finite-time attitude cooperative control problem for a group of multiple unmanned aerial vehicle systems with external disturbances and uncertain parameters is discussed in this paper. The dynamics of the systems is described by quaternion avoiding the singularity. Based on the attitude error and angular velocity error, a novel nonsingular terminal sliding mode surface is proposed for the controller with event-triggered scheme. The lumped disturbances are estimated by neural networks with adaptive law. The communication frequency is decreased by the proposed distributed event-triggered based sliding mode controller. Lyapunov theory is utilized to analyze the stability of the systems, and the Zeno behavior is avoided by rigorous proof. Finally, simulation examples are presented to illustrate the efficiency of the proposed control algorithm., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Qiang Han et al.)

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.

To improve the visible light absorption and photocatalytic activity of titanium dioxide nanotube arrays (TONTAs), ZnFe 2 O 4 (ZFO) nanocrystals were perfused into pristine TONTA pipelines using a novel bias voltage-assisted perfusion method. ZFO nanocrystals were well anchored on the inner walls of the pristine TONTAs when the ZFO suspensions (0.025 mg mL -1 ) were kept under a 60 V bias voltage for 1 h. After annealing at 750 °C for 2 h, the heterostructured ZFO/Fe 2 TiO 5 (FTO)/TiO 2 composite nanotube arrays were successfully obtained. Furthermore, Fe 3+ was reduced to Fe 2+ when solid solution reactions occurred at the interface of ZFO and the pristine TONTAs. Introducing ZFO significantly enhanced the visible light absorption of the ZFO/FTO/TONTAs relative to that of the annealed TONTAs. The coexistence of type I and staggered type II band alignment in the ZFO/FTO/TONTAs facilitated the separation of photogenerated electrons and holes, thereby improving the efficiency of the ZFO/FTO/TONTAs for photocatalytic degradation of methylene blue when irradiated with simulated sunlight.

An online automatic Ti-grade analyzer (OATGA), consisting of a (238)Pu 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 5 min. 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 2009 Elsevier Ltd. All rights reserved.)