Phosphogypsum is a by-product of the wet production of phosphoric acid. Its long-term and large-scale open-air storage may cause soil and groundwater pollution. Utilization of phosphogypsum resources has become a focus of recent attention. In order to identify research hotspots and development directions in this field， relevant literature on phosphogypsum resource utilization from January 2002 to January 2025 was collected， using the Web of Science （WoS） core database and the China National Knowledge Infrastructure （CNKI） database as data sources. The CiteSpace software was used to analyze these papers， and the relevant knowledge graphs were constructed. The research status， hotspots and main existing problems in this field have been summarized， and key development trends have been identified. The results show that in recent years the number of articles on the utilization of phosphogypsum resources has steadily increased. China has published the largest number of papers in this field and plays a leading role in international cooperation. Phosphogypsum resource utilization has gradually diversified from a single research direction. Technological applications and policy orientation of phosphogypsum resource utilization in China have been the main threads throughout the entire process. Research hotspots in phosphogypsum resource utilization include building materials， environmental remediation， soil improvement and conditioning components， and the preparation/recovery of high-value products. The main unresolved problems are that the impurity components in phosphogypsum affect product performance， commercializing laboratory research results is difficult， and that uniform standards are lacking.

The thermal decomposition process of 2，2'-azodi（2-methylbutyronitrile） （AMBN）， a typical oil-soluble azo initiator， is accompanied by the release of highly toxic gases and the potential risk of ignition and explosion， bringing significant safety challenges in its chemical production， storage and transportation. The pyrolysis pathway and kinetic properties of AMBN were systematically investigated using ReaxFF–MD simulations and thermogravimetric analysis （TG/DTG）. The simulation results showed that the azo bonds were preferentially broken at high temperatures， and small-molecule products such as N₂， HCN， and C₂H₂ were generated. The average apparent activation energy calculated based on conversion rate methods， such as the Flynn-Wall-Ozawa （FWO） and Kissinger-Akahira-Sunose （KAS） methods， was 102 kJ/mol， and the Coats-Redfern method showed that the second order （F2） model is the most suitable mechanistic function model for AMBN. This study provides a theoretical basis for the precise control and safety assessment of the thermal sensitivity of AMBN in industrial applications.

Electrolytic cells for alkaline water hydrogen production are a core component of the hydrogen production platform， and their performance affects the purity and efficiency of hydrogen production. To date， studies of electrolytic cells for alkaline water hydrogen production have mostly focused on the internal flow field distribution in the inlaid spherical convex and concave flow channels. Most electrolytic cells adopt a single-inlet design， preventing an analysis of the internal flow field distribution law within the flow channels when varying the number of inlets. For this purpose， an alkaline electrolytic water hydrogen production test platform with a hydrogen production capacity of 10 Nm³/h was fabricated. The effects of varying the system pressure and working temperature on the performance of the hydrogen production electrolytic cell were investigated. The results show that when the system pressure increases， both the electrolytic current and the oxygen content in the evolved hydrogen increase. When the working temperature rises， the electrolytic current increases and the oxygen content in hydrogen decreases. Based on the design parameters of the test platform， a single-inlet channel model of the electrode plate was constructed. In addition， electrode plate flow channels with double- and triple-inlets were designed. The flow field distribution characteristics within the flow channels were analyzed using computational fluid dynamics （CFD）. The results show that the vortex distribution in the single-inlet and double-inlet flow channels is wide， forming a low-speed wake area， with a large velocity gradient and an uneven flow field. The vortex area of the triple-inlet flow channel is small， the flow field gradient is low， and the distribution is relatively uniform. This shows that the number and structure of the inlets significantly affect the turbulent kinetic energy of the electrolyte. A single-inlet channel is prone to form a highly turbulent zone， while double- and triple-inlet channels weaken the peak by diverting flow， making the turbulent kinetic energy distribution more uniform. Furthermore， the symmetrical structure of the double inlets can enhance the regularity of the turbulent kinetic energy distribution.

Based on a combination of experiment and simulation， the heat transfer and flow performance of a dual-layer wide-folded blade impeller in a stirred tank equipped with an inner-heat coil have been investigated for different impeller spacings. Sodium carboxymethyl cellulose solution （a non-Newtonian fluid） was used as the working fluid. The results show that the impeller spacing has a significant influence on the distribution of the flow field and temperature field in the tank. When the impeller spacing increases from 0.32T （where T is the diameter of the stirred tank） to 0.39T， the changes in the flow field and velocity distribution in the tank are relatively small， but the average temperature of the fluid in the tank increases， the temperature difference decreases， and the stirring power decreases by 3.82%. When the impeller spacing increases from 0.39T to 0.46T， the temperature increase inside the tank is relatively small， but the temperature difference increases. The connection flow between the upper and lower layers of the impeller decreases， resulting in an area where the axial velocity is close to zero， which results in an extension of the mixing time. During the stirring process， the viscosity of the fluid in the tank decreases with increasing shear rate and temperature. In the initial stages of stirring， the viscosity of the fluid drops rapidly due to the increase in shear rate. Subsequently， the viscosity is affected by the combined effects of shear and temperature. Finally， after uniform mixing， the viscosity is mainly affected by temperature. These results provide a reference for the practical industrial application of non-Newtonian fluid stirring.

The heat transfer performance of a spiral tube is enhanced by combining pulsating flow with a dimpled wall structure. Firstly， the influence of the layout parameters of the dimples on the steady-state heat transfer characteristics of the fluid in the spiral tube， over the Reynolds number range 7 000 to 11 000， was studied through numerical simulation. Then， the combined heat transfer enhancement effect of pulsating flow combined with the dimpled structure on the spiral tube was analyzed， and the mechanism of enhanced heat transfer was postulated. The results show that， under steady-state conditions， the overall heat transfer performance along both the flow direction and the circumferential direction of the dimpled structure with an aspect ratio of a/b>1 is superior to that of the dimpled structure with a/b≤1. The comprehensive heat transfer enhancement effect reaches a maximum when the circumferential layout quantity n=3 and the helical spacing angle φ=π/3. The addition of pulsating flow further enhances the turbulence intensity of the fluid near the dimples， improves the coordination between the velocity and temperature fields， and， during more than half of the pulsation period， the average Nusselt number Nu is higher than the steady-state value. Within the scope of the study， the comprehensive enhanced heat transfer effect of the helical tube is optimized when the dimensionless pulsation amplitude A is 0.25 and the dimensionless frequency Wo is 13.26， with the values of the performance evaluation criterion （PEC） in the range 1.051 to 1.079. When Re=7 000， the PEC value of the dimpled structure combined with pulsating flow increased by 1.35%-2.08% compared to the value for a single pulsating flow， and by 2.19%-4.76% compared to the value for a single dimpled structure.

Suspended oil， a critical component of liquid floated gyroscopes， experiences localized density variations due to uneven temperature distribution in the working environment， leading to disturbing torque. This study employed molecular dynamics simulations to investigate the effects of varying molecular weight， polymer dispersity index （PDI）， and temperature on the density of fluorinated ether polymers. Multiple density simulation models of fluorinated ether polymers with varying molecular weights were successfully constructed and analyzed at different temperatures. The experimental data showed that the density of fluorinated ether polymers increases linearly with molecular weight. Additionally， the density of fluorinated ether polymers decreases with increasing temperature， and their density becomes less temperature-sensitive with increasing molecular weight. Fluorinated ether polymers with low PDI show smaller density variations with temperature changes， confirming their stronger resistance to temperature fluctuations. This study provides theoretical foundations and data support for the development of future applications of suspended oil.

CuS@PDA/MoS₂ （PDA = polydopamine） composite photocatalytic nanoparticles with highly efficient synergistic natural light/heat conversion have been prepared by hydrothermal reaction. In the first step， CuS@PDA nanoparticles with a core⁃shell structure were obtained by in situ oxidative polymerization of dopamine on the surface of CuS nanoparticles. In the second step， MoS₂ nanoparticles were generated in situ on the surface of the CuS@PDA nanoparticles by thermal reaction. The nanoparticles were characterized by SEM， TEM， XRD and XPS， which confirmed that CuS@PDA/MoS₂ nanoparticles with a three-layer structure had been successfully synthesized. CuS@PDA/MoS₂/PLA （PLA = polylactic acid） photocatalytic nanofiber functional membranes were fabricated by solution electrospinning， and their filtration and photocatalytic performance were investigated. It was found that the addition of CuS@PDA/MoS₂ photocatalytic nanoparticles significantly improved the natural light and heat conversion of polylactic acid fibers. Under irradiation by 1 kW/m² simulated natural light， the temperature rise of the polylactic acid fiber membrane after addition of 5% CuS@PDA/MoS₂ photocatalytic nanoparticles was 9.2 ℃ higher than that of the pure polylactic acid fiber membrane， and the filtration efficiency of the fiber membrane retained 96% of its original capacity after four weeks of tracking tests. The efficiency retention rate of the polylactic acid fiber membrane after the addition of 5% filler was 99.29%， which was higher than that of the pure polylactic acid fiber membrane （98.12%）.

Driven by the demands of environmental protection and sustainable development， bio-based polyurethanes exhibit promising application prospects as green damping materials. However， research on their application in vibration and noise reduction remains insufficient， and their damping performance still requires further enhancement. In this work， a bio-based polyurethane elastomer was synthesized using bio-based poly（trimethylene ether） glycol （PO3G） as the soft segment. Composites of the hindered phenol AO-80 and the bio-based polyurethane elastomer were prepared via physical blending. A systematic characterization of hydrogen bonding interactions， mechanical properties， and damping behavior was conducted using Fourier transform infrared spectroscopy， differential scanning calorimetry， tensile testing， and dynamic mechanical analysis. The experimental results indicate that with the increasing AO-80 content results in stronger hydrogen bonding within the composites strengthens. Consequently， the tensile strength improved from 6.3 MPa to 10.2 MPa， the elongation at break increased from 209% to 321%， the glass transition temperature rose from -43.2 ℃ to -23.8 ℃， and the maximum loss factor （tanδ _max） enhanced from 0.71 to 1.06. This work provides a novel approach for developing high-performance bio-based polyurethane damping materials.

In real industrial applications， large amounts of unlabeled streaming data are typically generated， presenting a series of challenges in their effective utilization. This study uses unsupervised clustering methods to analyze these data sets and reveal potential patterns and structures， thereby providing effective support and decision points for optimization of industrial production processes. Given the spatial nonlinearity and complex geometric shapes of the streaming data， local linear embedding is used to map data from high-dimensional， non-linear， concave-convex characteristics to lower-dimensional， relatively linear characteristics， thereby achieving feature extraction. Conventional spectral clustering algorithms use Euclidean distance to measure similarity， which does not adequately capture the non-linear nature of the data. In contrast， our method combines the Minkowski distance and cosine similarity to more accurately measure the similarity between data points and thereby improve clustering effectiveness. The method was validated on real industrial coal gasification data， industrial wastewater treatment data， and two public datasets. Comparison with other clustering algorithms demonstrated the superior clustering performance of our method.

In order to address the lack of a combined waveform mode model that reflects the characteristics of rapid changes in DC amplitude and the unclear impact of dynamic energy signal excitation on the dynamic error of DC energy meters， this paper adopts a mechanism modeling approach. Firstly， mathematical models are established for the signal preprocessing unit， signal conversion unit， and power and energy measurement unit of the DC energy meter. Secondly， a set of typical DC dynamic waveform modes is defined， and mathematical models for four typical examples are established， followed by the construction of a combination waveform mode dynamic energy test signal model. Then， the impact of the programmable gain amplifier （PGA）， power filter， and energy accumulation unit on the dynamic error of the DC energy meter is analyzed through simulations using a dynamic energy test signal as the input. Finally， the dynamic errors in the energy meter caused by the PGA gain switching delay， filter length， and power threshold of the energy accumulation unit under dynamic energy test waveform excitation are analyzed. Our conclusions provide a theoretical basis for improving the dynamic error characteristics of energy meters.

Image recognition of concrete surface cracks using neural network models has become an effective method for identifying defects in concrete buildings. However， the accuracy of crack recognition is affected by the fuzzy images acquired during the motion of recognition devices mounted on drones and smart vehicles. The high complexity of deep neural network models limits their application in devices for the intelligent identification of concrete cracks. Therefore， in this work， a lightweight concrete crack image recognition network based on a deblurring generative adversarial network and mobile network （DeblurGAN-MobileNet） model has been designed to effectively improve the accuracy and inference rate of concrete crack image recognition in motion blur background. Firstly， in the feature pyramid network （FPN） of DeblurGAN-V2 for motion deblurring， we adopted an “X”⁃shaped cross network to improve the internal structure of the FPN. This addresses the issue of uneven resolution contribution and significant information loss in the highest and lowest dimensions during cross-scale feature fusion. Secondly， we incorporated dilated convolutions with different dilation rates into the Bottleneck of the MobileNetV3 image classification network and gradually cascaded them through the network. This not only reduces the computational complexity of the network but also enlarges the receptive field without altering the image dimensions， ultimately enhancing recognition accuracy. The experimental results of motion blur restoration and crack image recognition on different datasets show that our method performs excellently in terms of motion blur removal and recognition accuracy with a motion blur background. Using the GOPRO dataset and a self-made concrete image dataset， the peak signal-to-noise ratio （PSNR） reached 23.51 and 21.95， respectively. Using this method， the recognition accuracy （P） for concrete crack images was 0.889， with an average fast inference speed of only 0.47 seconds per image.

In a liquid metal fast reactor， the mixing of coolant from the core outlet in the upper plenum induces temperature fluctuations in the adjacent wall temperature field， which can lead to thermal fatigue of structural components. This study uses computational fluid dynamics （CFD） software and employs large eddy simulation （LES） to numerically simulate temperature fluctuations in a parallel three-nozzle model. The accuracy of the simulation method is first validated against existing experimental data. A subsequent comparative analysis examines the frequency and amplitude of temperature fluctuations for three liquid metal coolants： lead-bismuth eutectic （LBE）， liquid lead （Pb）， and liquid sodium （Na）. The results show that， in the parallel three-nozzle model， temperature fluctuations are more pronounced for lead-based coolants， increasing the risk of thermal fatigue in structural components.

The start-up process of a high-speed centrifugal pump is typically nonlinear. Traditional proportional-integral-differential （PID） controllers and sliding mode controllers （SMC） suffer from problems such as large speed overshoot， slow approach to sliding mode surfaces， poor stability and system chattering. In order to mitigate these issues and improve the control performance during start-up， a new fuzzy sliding mode controller is proposed in this work. A nonlinear mathematical model of the start-up process of the high-speed centrifugal pump is first established. A new sliding mode reaching law is then designed using a nonlinear power combination function and a hyperbolic tangent function， and the stability of the system is proved. A fuzzy algorithm is then introduced to adjust the coefficient of the reaching law in real time， so that the reaching process is dynamically controlled， and the performance of the controller is further optimized. Finally， a simulation model is built in Simulink for experimental verification. The results show that after incorporating the new fuzzy sliding mode controller， the dynamic response of the centrifugal pump system during start-up is fast， and it quickly converges to a stable state without overshoot. Furthermore， it exhibits good anti-chattering performance and strong robustness to external load disturbances.

We have studied the global existence of weak solutions for compressible Navier⁃Stokes/Allen⁃Cahn （NSAC） systems with slip boundary conditions， which describe the flow of immiscible two⁃phase flow with diffusion interfaces. Under the conditions of limited initial energy and adiabatic constant \gamma > \mathrm{2}， the global existence of weak solutions for initial boundary value problems with Navier⁃slip boundary conditions is proved using the Faedo⁃Galerkin approximation and a weak convergence limit.