In this study, nano-graphene reinforced titanium matrix composites (GNPs/Ti) with a honeycomb porous structure were fabricated by selective laser melting (SLM). The effects of graphene on the microstructure, mechanical properties and corrosion performance of the SLM GNPs/Ti were systematically investigated. Results of microstructure characterization show that: 1) the density of the SLM GNPs/Ti was improved as compared to that of the SLM Ti; 2) abundant TiC particles were formed in the SLM GNPs/Ti. The hardness and compressive strength of the composite increased by 90% (from HV 236 to HV 503) and 14% (from 277 MPa to 316 MPa), respectively, attributed to the uniformly distributed TiC and fine GNPs in the Ti matrix. Electrochemical tests reveal that the corrosion current density of the SLM GNPs/Ti is only 0.328 μA/cm², that is about 25% less than that of the SLM Ti. The results indicate that the incorporation of nano-graphene is a potential method to strengthen the Ti by SLM.

The effects of hot extrusion and addition of Al₂O_3p on both microstructure and tribological behavior of 7075 composites were investigated via optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and transmission electron microscopy (TEM). The experimental consequences reveal that the optimal addition of Al₂O_3p was 2 wt%. After hot extrusion, the Mg(Zn,Cu,Al)₂ phases partially dissolve into the matrix and generate many uniformly distributed aging precipitation particles, the Al₇Cu₂Fe phases are squeezed and broken, and the Al₂O_3p become uniform distribution. The microhardness of as-extruded 2 wt% Al₂O_3p/7075 composites reaches HV 170.34, increased by 41.5% than as-cast composites. The wear rate of as-extruded 2 wt% Al₂O_3p/7075 composites is further lower than that of as-cast composites under the same condition. SEM-EDS analyses reveal that the reinforced wear resistance of composites can put down to the protective effect of the Al₂O_3p reinforced transition layer. After hot extrusion, the transition layer becomes stable, which determines the reinforced wear resistance of the as-extruded composites.

The effect of temperature in range of 155–175 °C on the creep behavior, microstructural evolution, and precipitation of an Al-Cu-Li alloy was experimentally investigated during creep ageing deformation under 180 MPa for 20 h. Increasing temperature resulted in a noteworthy change in creep ageing behaviour, including a variation in creep curves, an improvement in creep rate during early creep ageing, and an increased creep strain. Tensile tests indicate that the specimen aged at higher temperature reached peak strength within a shorter time. Transmission electron microscopy (TEM) was employed to explore the effect of temperature on the microstructural evolution of the AA2198 during creep ageing deformation. Many larger dislocations and even tangled dislocation structures were observed in the sample aged at higher temperature. The number of T₁ precipitates increased at higher ageing temperature at the same ageing time. Based on the analysed results, a new mechanism, considering the combined effects of the formation of larger dislocation structures induced by higher temperature and diffusion of solute atoms towards these larger or tangled dislocations, was proposed to explain the effect of temperature on microstructural evolution and creep behaviour.

B₄C/6061Al composites reinforced with nano- to micrometer-sized B₄C particles were fabricated via powder metallurgy route consisting of spark plasma sintering (SPS) and hot extrusion and rolling (HER), followed by T6 treatment. The microstructural evolution and mechanical properties were investigated. Results showed that the status of B₄C particles changed from a network after SPS to a dispersion distribution after HER. The substructured grains reached 66.5% owing to the pinning effect of nano-sized B₄C, and the grain size was refined from 3.12 μm to 1.56 μm after HER. After T6 treatment, dispersed Mg₂Si precipitated phases formed, and the grain size increased to 1.87 μm. Fine recrystallized grains around micro-sized B₄C were smaller than those in the areas with uniform distribution of nano-sized B₄C and Mg₂Si. The stress distributions of as-rolled and heated composites were similar, considering that the T6 heat treatment was only effective in eliminating the first internal stress. The Vickers, microhardness, and tensile strength of as-SPSed composites were greatly improved from HV 55.45, 0.86 GPa, and 180 MPa to HV 77.51, 1.08 GPa, and 310 MPa, respectively. Despite the precipitation strengthening, the corresponding values of as-heated composites decreased to HV 70.82, 0.85 GPa, and 230 MPa owing to grain coarsening.

In this paper, the 2.6vol%TiBw/Ti6Al4V composites with network architecture were fabricated by hot press sintering (HPS) at 1100 °C for 1 h, and the quantitative relationships between phases and heat treatment temperatures were established. The results showed that the volume fraction phases changed linearly with a range of solution temperature (930–1010 °C) and aging temperature (400–600 °C). Moreover, the composites with equiaxed microstructure were obtained due to the static recrystallization after solution treated at 950 °C for 1 h and aging treated at 600 °C for 12 h. The ultimate high temperature tensile strengths were 772, 658, 392 and 182 MPa, and the elongations were 9.1%, 12.5%, 28.6% and 35.3% at 400, 500, 600 and 700 °C, respectively. In addition, fractured morphology analysis indicated the excellent strengthening effect of TiBw at a temperature below 600 °C. However, the strengthening effect was significantly reduced due to the debonding of matrix and TiBw at 700 °C and caused the cracks to propagate along the grain boundary.

Waste cathode ray tube (CRT) funnel glass (FG) is an important part in the disposal of electrical and electronic waste (e-waste). A novel approach for efficient lead extraction and glass-ceramics synthesized from waste FG through collaboratively smelting FG with coal fly ash (CFA) is proposed. Glass-ceramics materials with 40 wt%–80 wt% FG additions were produced under sintering temperatures of 900–1000 °C. The microstructure and phase composition of the produced glass-ceramics were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The density, water absorption, Vicker hardness, chemical resistance and heavy metal leaching characteristics of the glass-ceramics were measured. The experimental results indicate that the samples can be crystallized at sintering temperatures of 900–1000 °C. An elevated sintering temperature is favorable for enhancing the degree of crystallization, while the crystallization process is inhibited at excessively high temperatures. Increasing FG addition can lead to the transformation of the main crystalline phase from diopside to gehlenite. Well-crystallized crystals were generated in the specimens with 50 wt%–70 wt% FG additions. The samples with 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt% FG addition exhibit the optimal chemical and physical properties at 975, 925, 950, 925 and 900 °C, respectively. Overall results demonstrate that this study provides a feasible strategy for reliably detoxifying and reusing waste FG and CFA.

To make up the poor quality defects of traditional control methods and meet the growing requirements of accuracy for strip crown, an optimized model based on support vector machine (SVM) is put forward firstly to enhance the quality of product in hot strip rolling. Meanwhile, for enriching data information and ensuring data quality, experimental data were collected from a hot-rolled plant to set up prediction models, as well as the prediction performance of models was evaluated by calculating multiple indicators. Furthermore, the traditional SVM model and the combined prediction models with particle swarm optimization (PSO) algorithm and the principal component analysis combined with cuckoo search (PCA-CS) optimization strategies are presented to make a comparison. Besides, the prediction performance comparisons of the three models are discussed. Finally, the experimental results revealed that the PCA-CS-SVM model has the highest prediction accuracy and the fastest convergence speed. Furthermore, the root mean squared error (RMSE) of PCA-CS-SVM model is 2.04 µm, and 98.15% of prediction data have an absolute error of less than 4.5 µm. Especially, the results also proved that PCA-CS-SVM model not only satisfies precision requirement but also has certain guiding significance for the actual production of hot strip rolling.

The exploration of stable and highly efficient alkaline hydrogen evolution reaction (HER) electrocatalysts is imperative for alkaline water splitting. Herein, Se-doped NiCoP with hierarchical nanoarray structures directly grown on carbon cloth (Se-NiCoP/CC) was prepared by hydrothermal reaction and phosphorization/selenization process. The experimental results reveal that Se doping could increase the electrochemical active sites and alter the electronic structure of NiCoP. The optimized Se-NiCoP/CC electrode exhibits outstanding HER activity in alkaline electrolyte, which only needs a low overpotential of 79 mV at the current density of 10 mA/cm². When serving as anode and cathode electrode simultaneously, the Se-NiCoP/CC electrodes achieve current density of 50 mA/cm² at a low voltage of only 1.62 V. This work provides a feasible way to rationally design high active HER electrocatalysts.

Floor water inrush is one of the main types of coal mine water hazards. With the development of deep mining, the prediction and evaluation of floor water inrush is particularly significant. This paper proposes a variable weight model, which combines a multi-factor interaction matrix (MFIM) and the technique for order performance by similarity to ideal solution (TOPSIS) to implement the risk assessment of floor water inrush in coal mines. Based on the MFIM, the interaction between seven evaluation indices, including the confined water pressure, water supply condition and aquifer water yield property, floor aquifuge thickness, fault water transmitting ability, fracture development degree, mining depth and thickness and their influence on floor water inrush were considered. After calculating the constant weights, the active degree evaluation was used to assign a variable weight to the indices. The values of the middle layer and final risk level were obtained by TOPSIS. The presented model was successfully applied in the 9901 working face in the Taoyang Mine and four additional coal mines and the results were highly consistent with the engineering situations. Compared with the existing nonlinear evaluation methods, the proposed model had advantages in terms of the weighting, principle explanation, and algorithm structure.

External return mechanism is a mechanical structure applied to axial piston pumps. To study its lubrication characteristics, the Reynolds equation applied to an external return spherical hinge pair was deduced based on the vector equation of relative-motion velocity of the external return spherical hinge pair under the influence of external swash plate inclination and offset distance. The results show that the total friction, axial leakage flow, and maximum value of the maximum oil-film pressure increase with increasing pump-shaft speed and decrease with increasing offset distance in one working cycle when the external-swash-plate inclination is constant. However, the varying offset distance has little effect on the axial leakage flow. The maximum value of the maximum oil-film pressure decreases with increasing external-swash-plate inclination and the total leakage flow increases with increasing external-swash-plate inclination in one working cycle when the offset distance is constant. It can be seen that the abovementioned parameters are important factors that affect the lubrication characteristics of external return spherical hinge pairs. Therefore, the complex effects of different coupling parameters should be comprehensively considered in the design of the external return mechanism.

The buckling resisting brace (BRB) is an efficient system against lateral loads that enjoy high seismic energy absorption capacity. Although desirable behavior of BRBs has been confirmed, the stiffness of the system is not desirable that it can be compensated by changing the configuration of BRB braces. In so doing, the configuration in the form of double K (DK) is investigated to achieve more favorable behavior. Also, the required mathematical formulas were proposed to design the system. Comparison of DK system with other conventional BRB showed that the DK system has a better structural performance and is more economical (due to needing less core area) than other conventional BRB. Numerical results indicated that the DK system increases the lateral ultimate strength, lateral nonlinear stiffness, and energy absorption. Besides, the DK configuration reduces the axial forces created in columns in the nonlinear zone. Reducing material demand, created forces in the main frame, and also increasing of nonlinear stiffens by DK improve the structure’s safety.

Extensive studies have been carried out for reliability studies on the basis of the surrogate model, which has the advantage of guaranteeing evaluation accuracy while minimizing the need of calling the real yet complicated performance function. Here, one novel adaptive sampling approach is developed for efficiently estimating the failure probability. First, one innovative active learning function integrating with Jensen-Shannon divergence (JSD) is derived to update the Kriging model by selecting the most suitable sampling point. For improving the efficient property, one trust-region method receives the development for reducing computational burden about the evaluation of active learning function without compromising the accuracy. Furthermore, a termination criterion based on uncertainty function is introduced to achieve better robustness in different situations of failure probability. The developed approach shows two main merits: the newly selected sampling points approach to the area of limit state boundary, and these sampling points have large discreteness. Finally, three case analyses receive the conduction for demonstrating the developed approach’s feasibility and performance. Compared with Monte Carlo simulation or other active learning functions, the developed approach has advantages in terms of efficiency, convergence, and accurate when dealing with complex problems.

In view of the fact that traditional job shop scheduling only considers a single factor, which affects the effect of resource allocation, the dual-resource integrated scheduling problem between AGV and machine in intelligent manufacturing job shop environment was studied. The dual-resource integrated scheduling model of AGV and machine was established by comprehensively considering constraints of machines, workpieces and AGVs. The bidirectional single path fixed guidance system based on topological map was determined, and the AGV transportation task model was defined. The improved A* path optimization algorithm was used to determine the optimal path, and the path conflict elimination mechanism was described. The improved NSGA-II algorithm was used to determine the machining workpiece sequence, and the competition mechanism was introduced to allocate AGV transportation tasks. The proposed model and method were verified by a workshop production example, the results showed that the dual resource integrated scheduling strategy of AGV and machine is effective.

Wafer bin map (WBM) inspection is a critical approach for evaluating the semiconductor manufacturing process. An excellent inspection algorithm can improve the production efficiency and yield. This paper proposes a WBM defect pattern inspection strategy based on the DenseNet deep learning model, the structure and training loss function are improved according to the characteristics of the WBM. In addition, a constrained mean filtering algorithm is proposed to filter the noise grains. In model prediction, an entropy-based Monte Carlo dropout algorithm is employed to quantify the uncertainty of the model decision. The experimental results show that the recognition ability of the improved DenseNet is better than that of traditional algorithms in terms of typical WBM defect patterns. Analyzing the model uncertainty can not only effectively reduce the miss or false detection rate but also help to identify new patterns.

Vibration-based pavement condition (roughness and obvious anomalies) monitoring has been expanding in road engineering. However, the indistinctive transverse cracking has hardly been considered. Therefore, a vehicle-based novel method is proposed for detecting the transverse cracking through signal processing techniques and support vector machine (SVM). The vibration signals of the car traveling on the transverse-cracked and the crack-free sections were subjected to signal processing in time domain, frequency domain and wavelet domain, aiming to find indices that can discriminate vibration signal between the cracked and uncracked section. These indices were used to form 8 SVM models. The model with the highest accuracy and F1-measure was preferred, consisting of features including vehicle speed, range, relative standard deviation, maximum Fourier coefficient, and wavelet coefficient. Therefore, a crack and crack-free classifier was developed. Then its feasibility was investigated by 2292 pavement sections. The detection accuracy and F1-measure are 97.25% and 85.25%, respectively. The cracking detection approach proposed in this paper and the smartphone-based detection method for IRI and other distress may form a comprehensive pavement condition survey system.

Electromagnetic signals may be a promising precursor to seismic activity which has been observed in many case studies in past decades. However, the correlation and causation between the electromagnetic signals and the seismic activity are still unclear without intensive observation network. In order to find seismoelectromagnetic phenomenon, we deployed AETA (acoustic and electromagnetic testing all-in-one system), a high-density multi-component seismic monitoring system in the China Earthquake Science Experiment site (CESE, in Sichuan Province and Yunnan Province, China) and the capital circle (areas with a distance which is ≤200 km from Beijing), to record electromagnetic and geo-acoustic data across 0.1 Hz–10 kHz. In the course of data collection, we discovered an electromagnetic waveform that occurs on a daily basis. Because the signal generally coincides with sunrise and sunset, we named this phenomenon the SRSS (Sunrise-Sunset) waveform. After conducting three statistical tests based on seismicity and SRSS, we determined that the SRSS waveform is roughly correlated with the onset of seismic activity. It generally occurs at the regions where seismicity occurs. This discovery might have significant implications with respect to the future of earthquake prediction.

Rockburst is one of the major disasters in deep underground rock mechanics and engineering. The precursors of rockbursts play important roles in rockburst prediction. Strainburst experiments were performed under double-face unloading on sandstone with horizontal bedding planes using an independently designed rockburst testing facility. P-wave propagation time during the tests was automatically recorded by the acoustic emission apparatus. The P-wave velocities were calculated in both two directions to analyze their patterns. To find a characteristic precursor for rockburst, the dynamic evolution of rock anisotropy during the rockburst test is quantified by the anisotropic coefficient k, defined as the ratio of the two P-wave velocities in the directions vertical to and parallel to the bedding planes. The results show that rockburst occurs on the two free surfaces asynchronously. The rockburst failure occurs in the following order: crack generation, rock peeling, particle ejection, and rock fracture. In the process of rockburst under double-face unloading, the potential evolution characteristics of anisotropy can be generalized as anisotropy-isotropy-anisotropy. The suddenly unloading induces damage in the rock and presents anisotropic coefficient k steeply increasing departing from one, i.e., isotropy. The rocks with horizontal bedding planes will reach the isotropic state before rockburst, which could be considered as a characteristic precursor of this kind of rockburst.

Hollow cylindrical sandstone specimens filled with Al, Pb and polymethyl methacrylate (PMMA), as well as hollow and solid specimens were tested under monotonic unconfined compression. The discrepancies in the elastic modulus, unconfined compressive strength and failure pattern of the specimens were studied and then illustrated. The interaction stress threshold and localized failure stress threshold were identified by the strain gauges on the rock and filling rod. The results indicated that unobvious changes in the strength and elastic modulus were found between the solid and hollow specimens, while for the hollow specimens with infillings, the strength decreases with increasing the stiffness of the infilling material. The filling material with a higher stiffness leads to a high hoop stress, and hence a stronger interfacial force. The specimens coupled with filling rod are mainly fractured with tensile cracks, while the solid and hollow specimens are typically split into blocky fragments with dominated shear fractures. Finally, the equivalent inner pressure in the opening was theoretically derived. The findings suggested in the experiments can be well explained using the theoretical thick-walled cylinder model.

Directional rupture is one of the difficult problems in deep rock mechanics and engineering. A directional fracturing method with static expansive agent controlled by dense linear multi boreholes is proposed. A physical experiment is designed and performed to investigate the basic laws of this method. The fracture initiation and propagation process, and the mechanism of directional fracturing are analyzed. The results indicate that a directional fracture is formed along the direction of boreholes layout through directionally fracturing with static expansive agents controlled by the dense linear multi boreholes. According to the variation of strain and the distribution of associated acoustic emission (AE) events and energy, the experiment can be divided into three stages. In the first stage, the static expansive agent expand slowly with no fracturing inside the rock. In the second stage, some initial micro-fracturing occurs inside the rock. In the third stage, a wide range of fracturing occurs inside the sample. The internal micro-fracturing planes are connected to form a macro-fracture. Finally, it propagates to the surface of the sample. The directional fracturing plane presents a relatively smooth plane with little bias but much local fluctuation.

Geotechnical engineering that relates to the energy and environmental problem is receiving more and more attention worldwide. It is of great theoretical and practical value to study the properties of soil under thermal mechanical coupling and its mathematical description. Firstly, based on the general function, a unified primary and secondary consolidation model of saturated soil considering heating temperature is deduced. Combining the existing research achievements, a practical model is obtained which comprehensively reflects the effective stress change, creep and heating effects. After that, a series of thermo-consolidation tests are carried out using a temperature controlled consolidation instrument to study the effects of effective stress, temperature and consolidation duration on saturated soils. The corresponding functional formulas and parameters are obtained thusly. On this basis, the calculation and analysis are carried out to check the reliability and applicability of the newly proposed model. The new model is simple and practical and the parameters are easy to be obtained. And it describes the main law of consolidation compression of saturated soils under the thermal mechanical coupling effect. Therefore, it is suggested for theoretical analysis of thermal geotechnical engineering problems.

From a financial point of view, urbanization frequently enforces the clients to construct superstructures near the slopes, giving rise to increasing the risk of building instability. By conducting a series of small-scale plate load tests, this work aims to investigate the effects of installing geotextile reinforcement layers in sandy slope and reducing the apex angle of triangular shell strip footings. The results show considerable effect of using geotextile-reinforced layers and decreasing the apex angle on the ultimate bearing capacity of shell foundations. With increasing foundation distance from the slope, the adverse effect of the slope is reduced. However, as the distance decreases, the effect of reinforcement and apex angle is increased. For practical applications, empirical equations are also presented for determining the ultimate bearing capacity of the footings and scale effect as well. Finally, 3D numerical simulations are executed and compared with the experimental results.

Combining vacuum preloading technology and electroosmosis can improve the treatment effect of soft soil foundation by utilizing the advantages of both methods. Many studies indicate that the soil electrical potential is non-linearly distributed in the treatment process by the combined method. However, in the previous theoretical study, the non-linear-distribution impacts of soil’s electrical potential on soft soil foundation treatment have not been considered. It is always assumed to be linear distribution, which is different from the experimental results. In this paper, the coupling consolidation model of this technology under the two-dimensional plane strain condition is initially established; and the well resistance effect, the vacuum load decreasing along the soil depth and the non-linear variation of electrical potential in the soil are considered. Then, the analytical solutions of the average excess pore water pressure and soil’s consolidation degree in the anode affected area are acquired based on the soil’s electrical potential distribution. Finally, the rationality of the analytical solution is testified by conducting an experimental model test, which proves the scientificity of the analytical solution. The analytical solution is adopted to better predict the dissipation of excess pore water pressure and soil consolidation degree when using the combined technology. This study can provide a reference with more accuracy for the engineering practices of this combined technology in the future.

When the tunnel underpasses through the building, it will cause deformation and even damage to the buildings above, and the deformation of building foundation is the key to building safety. Based on the engineering case, the theoretical analysis was employed to evaluate the influence of shield tunnel underpass construction on the stability of the building, and the optimal tunneling parameters in the field construction have been obtained through the verified theoretical model and parameter analysis. First, the strip foundation of the building was simplified to the Timoshenko beam, which was taken into account the shear effect, and then the deformation displacement of the soil at the same place of strip foundation was applied to the simplified Timoshenko beam. Finally, the numerical solution of the displacement of the strip foundation was obtained by using the finite element method and verified its reliability using Euler-Bernoulli beam theoretical model, field monitoring data, and numerical simulation. Parameters analysis for the deformation and internal force of strip foundation under different types of shield machine tunneling parameters showed that the influence of the pressure of shield excavation chamber, thrust of shield, and driving speed played an important role in the deformation of the building’s strip foundation and internal force.

At present, shield tunneling often needs to pass through a large number of bridge pile foundations. However, there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groundwater seepage. Based on Winkler model, the calculation equations of shield tunneling on vertical and horizontal displacement of adjacent bridge pile are derived. Meanwhile, full and part three-dimensional finite element models are established to analyze the trend of bridge pier settlement, ground surface settlement trough, vertical and horizontal displacement of the pile and pile stress under three calculation conditions, i.e., not considering groundwater effect, considering stable groundwater effect and fluid-soil interaction. The results show that the calculated value is small when the effect of groundwater is not considered; the seepage velocity of the soil above the excavation face is faster than that of the surrounding soil under fluid-soil interaction, and after the shield passing, the groundwater on both sides shows a flow trend of “U” shape on the ground surface supplying to the upper part of the tunnel; the vertical displacement of the pile body is bounded by the horizontal position of the top of the tunnel, the upper pile body settles, and the lower pile body deforms upward. The horizontal displacement of pile body presents a continuous “S” shape distribution, causing stress concentration near the tunnel. The calculated results of fluid-soil interaction are in good agreement with the field measured data and accord with the actual situation.