It is of great significance for safety reason to obtain the triaxial compressive properties of cemented tailings backfill(CTB). The influence of cement content, curing age and confining pressure on strength and deformation properties of CTB was examined and discussed. Results indicate that the triaxial compressive and deformation behavior of CTB is strongly affected by the cement content, curing age and confining pressure. The increase in cement content, curing age and confining pressure leads to a change in stress-strain behavior and an increase in the axial strain at failure and post-peak strength loss. The cohesion of CTB rises as the curing age and cement content increase. However, the enhancement in internal friction angle is trivial and negligible. It should be noted that the failure pattern of CTB samples in triaxial compression is mainly along a shear plane, the confining pressure restrains the lateral expansion and the bulging failure pattern is dominantly detected in CTB samples as curing age length and cement content increase. The results will help to better understand the triaxial mechanical and deformation behavior of CTB.

A large amount of acid-leaching residue is produced during the conventional Zn hydrometallurgy process, and this residue has a large concentration of a variety of valuable metals. The purpose of this study was to evaluate the ability of a procedure that entails the use of sulfation roasting, water leaching, and chlorination leaching (blowing oxygen technique) to recover Pb and Ag, followed by cooling crystallization and the replacement of Ag with lead sheet, to realize the full recovery of all valuable metals from zinc acid-leaching residue; consequently, good results were achieved. The best results were obtained under the following conditions: a sulfuric acid at 70% of the raw material quality, roasting temperature of 300 °C and roasting time of 2 h, followed by the process of leaching the roasted residue for 1 h by applying a water-to-solid ratio of 5:1 at room temperature. The recovery rates of Zn and Fe were 98.69% and 92.36%, respectively. The main parameters of the chlorine salt leaching system were as follows: Cl⁻ concentration of 300 g/L, Fe³⁺ concentration of 25 g/L, acid concentration of 2 mol/L, liquid-to-solid ratio of 9 mL:1 g, temperature of 90 °C, and leaching time of 0.5 h; this leaching process was followed by filtration separation. These conditions resulted in high extents of leaching for Pb and Ag (i.e., 98.87% and 96.74%, respectively). Finally, the kinetics of the process of Ag leaching using Cl⁻ ions in an oxygen-rich medium was investigated. It was found that the leaching process was controlled by the diffusion of the product layers, and the activation energy was 19.82 kJ/mol.

Hexagonal porous Nb₂O₅ was synthesized for the first time via a facile solid-state reaction. The structure and electrochemical properties have been optimized through tuning heating temperature. X-ray diffraction results indicate that pseudo hexagonal Nb₂O₅ (TT-Nb₂O₅) and orthorhombic Nb₂O₅ have been synthesized at different temperatures. Hexagonal sheet and porous structure of Nb₂O₅ were characterized by scanning electron microscopy and N₂-adsorption-desorption isotherms. The as-prepared TT-Nb₂O₅ (heated at 600 °C) shows the best performance with a remarkable charge capacity of 178 mA·h/g at 0.2C, which is higher than that of T-Nb₂O₅. Even at 20C, TT-Nb₂O₅ offers unprecedented rate capability up to 86 mA·h/g. The high rate capacity is due to pseudocapacitive Li⁺ intercalation mechanism of TT-Nb₂O₅. The reported results demonstrate that Nb₂O₅ with good crystal structure and high specific surface area is a powerful composite design for high-rate and safe anode materials.

TiN, which is ubiquitous in Ti-bearing steel, has a critical influence on both the mechanical properties and the welding process of steel, and therefore researche on the precipitation behavior of TiN in molten steel bath is of great significance. In this paper, Ti-bearing peritectic steel was taken as the study object and FactSage was adopted to explore how the precipitation behavior of typical inclusions in steel was affected by the steel composition. Furthermore, microsegregation models were used to analyze the precipitation process of TiN at solidification front, and the calculation results were finally verified by scanning electron microscope (SEM). Research showed that a multitude of dispersed particles of high melting oxide MgAl₂O₄ or MgO always existed in molten steel after magnesium treatment. In consideration of the segregation and enrichment of solute elements at the solidification front, the Ohnaka microsegregation model was employed to compute the precipitation during solidification. In the event of the solid fraction reaching 0.95 or more, the concentration product of [Ti][N] at the solidification front exceeded the equilibrium concentration product, then TiN began to precipitate. MgO or MgAl₂O₄ cores were generally found in TiN particles of peritectic steel after the magnesium treatment, which was consistent with the thermodynamic calculation results. Moreover, the average size of TiN particles was reduced by approximately 49%. This demonstrated that Mg-rich high melting inclusions were formed after the magnesium treatment, by which the heterogeneous nucleation of TiN was promoted it; therefore, favorable nucleation sites were provided for further refining the high-temperature ferrite phase.

In order to solve the problem of pressure shock on the continuous rotary electro-hydraulic servo motor, the mathematical models of pressure gradient under the structure of pre-compressed chamber and U-shaped groove were established. The optimal structure dimensions of the pre-compressed chamber and the U-shaped groove were determined. The fluid models were established by Solidworks under the four structures of triangular groove, triangular groove with pre-compression chamber, U-shaped groove and U-shaped groove with pre-compression chamber. Simulation analysis of depressurization process of fluid models was performed based on FLUENT. The pressure nephograms of different buffer structures were compared and analyzed, and the pressure change curves and pressure gradient change curves in the process of depressurization were obtained. The results show that the optimal edge length of the pre-compressed chamber of continuous rotary electro-hydraulic servo motor is 20 mm in the process of decompression. The pressure reduction effect is the best when the width of the U-shaped groove is 1.5 mm and the depth is 1.65 mm. The U-shaped groove structure with pre-compression chamber is more conducive to alleviate the pressure shock phenomenon of the motor compared with different combine buffer structures.

Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts. To accurately predict necking defects, new judgement conditions are established based on the thermal performance of 6082 aluminium alloy. The limit-sectional shrinkage without necking defects is achieved by combining theoretical calculation and finite-element model analysis, which couples heat transfer and deformation. In this paper, a 6082 aluminium alloy extruded rod with a 40 mm diameter rolled at a preheated temperature of 500 °C and a rolling angular velocity of 1 rad/s is taken as an example. The simulation and experimental results show that necking defects do not occur on the rolled pieces if the sectional shrinkage is below the limit-sectional shrinkage but will occur when the sectional shrinkage is above it. The results prove that the prediction model of necking defects in cross-wedge rolling of 6082 aluminum alloy is feasible, and this research provides a theoretical basis for the qualified aluminum alloy shafts produced by the cross-wedge rolling.

In order to meet the precision requirements and tracking performance of the continuous rotary motor electro-hydraulic servo system under unknown strong non-linear and uncertain strong disturbance factors, such as dynamic uncertainty and parameter perturbation, an improved active disturbance rejection control (ADRC) strategy was proposed. The state space model of the fifth order closed-loop system was established based on the principle of valve-controlled hydraulic motor. Then the three parts of ADRC were improved by parameter perturbation and external disturbance; the fast tracking differentiator was introduced into linear and non-linear combinations; the nonlinear state error feedback was proposed using synovial control; the extended state observer was determined by nonlinear compensation. In addition, the grey wolf algorithm was used to set the parameters of the three parts. The simulation and experimental results show that the improved ADRC can realize the system frequency 12 Hz when the tracking accuracy and response speed meet the requirements of double ten indexes, which lay foundation for the motor application.

As a new neural network model, extreme learning machine (ELM) has a good learning rate and generalization ability. However, ELM with a single hidden layer structure often fails to achieve good results when faced with large-scale multi-featured problems. To resolve this problem, we propose a multi-layer framework for the ELM learning algorithm to improve the model’s generalization ability. Moreover, noises or abnormal points often exist in practical applications, and they result in the inability to obtain clean training data. The generalization ability of the original ELM decreases under such circumstances. To address this issue, we add model bias and variance to the loss function so that the model gains the ability to minimize model bias and model variance, thus reducing the influence of noise signals. A new robust multi-layer algorithm called ML-RELM is proposed to enhance outlier robustness in complex datasets. Simulation results show that the method has high generalization ability and strong robustness to noise.

This paper proposes a novel reconfigurable Goldberg 6R linkage, conformed to the construction of variant serial Goldberg 6R linkage, while simultaneously satisfying the line-symmetric Bricard qualifications. The isomeric mechanism of this novel reconfigurable mechanism is obtained in combination with the isomerization method. The geometrically constrained conditions result in variable motion branches of the mechanism. Based on the singular value decomposition of the Jacobian matrix, the motion branches and branch bifurcation characteristics are analyzed, and the schematics of bifurcations in joint space is derived. This novel 6R linkage features one Goldberg 6R motion branch, two line-symmetric Bricard 6R motion branches, and one Bennett motion branch. With regards to the line-symmetric Bricard 6R motion branches, a similar function for the disassembly and recombination process can be achieved by reconstructing an intermediate configuration through bifurcation. Then, the isomerized generalized variant Goldberg 6R linkage is explicated in a similar way. Acting as a bridge, reconfigurability connects two families of overconstrained mechanisms.

In order to deal with the complex association relationships between classes in an object-oriented software system, a novel approach for identifying refactoring opportunities is proposed. The approach can be used to detect complex and duplicated many-to-many association relationships in source code, and to provide guidance for further refactoring. In the approach, source code is first transformed to an abstract syntax tree from which all data members of each class are extracted, then each class is characterized in connection with a set of association classes saving its data members. Next, classes in common associations are obtained by comparing different association classes sets in integrated analysis. Finally, on condition of pre-defined thresholds, all class sets in candidate for refactoring and their common association classes are saved and exported. This approach is tested on 4 projects. The results show that the precision is over 96% when the threshold is 3, and 100% when the threshold is 4. Meanwhile, this approach has good execution efficiency as the execution time taken for a project with more than 500 classes is less than 4 s, which also indicates that it can be applied to projects of different scales to identify their refactoring opportunities effectively.

Asphalt mixture pavement reheating is one of the important steps in hot in-place recycling (HIR). To improve the heating speed of asphalt pavement in HIR, based on the numerical analysis model of asphalt mixture heating process, a new multi-layer low-temperature heating method (MLHM) was proposed. Considering input heat flux, the thermal capacity and thermal resistance of asphalt mixture, the heat transfer model was established based on energy conservation law. By heating the asphalt mixture in layers, it changes the situation that the heat energy can only be input from the upper surface of the asphalt mixture pavement. Through the simulation of the heating method of asphalt mixture in the existing technology, the result shows that the existing heating methods lead to serious aging or charring of the asphalt mixture. By MLHM, the upper and the bottom of the asphalt mixture are heated at the same time, and the heating temperature is lower than other heat methods, which not only reduces the heating thickness and increases the heating area of the asphalt mixture pavement, but also improves the heating speed, saves the energy resource and ensures the heating quality. Especially, by MLHM, the heating uniformity is better and speed is faster.

In this paper, organic montmorillonite (OMMT) was added into crumb rubber modified asphalt (CRMA) to improve its high temperature performance, anti-aging performance and storage stability. The effects of different OMMT content on properties of CRMA were studied. The rutting factor obtained by dynamic shear rheological (DSR) test was adopted to evaluate the high-temperature performance. The creep stiffness and m value determined by the bending beam rheometer (BBR) test were employed to evaluate the low-temperature performance. The softening point, ductility, rutting factor before and after rolling thin film ovens test (RTFOT) and pressure aging vessel test (PAV) were compared to characterize the aging properties. Moreover, the segregation test after being reserved for 48 h and 7 d was conducted, and the softening point and rutting factor of upper and lower layers of segregation pipe were adopted to evaluate the storage stability. The results indicated that the high-temperature performance and anti-aging performance were developed with the increasing content of OMMT, while the low-temperature performance deteriorated. The storage stability was improved with the increasing content of OMMT before the content exceeded 4%, after which the storage stability declined. Taking account of all factors, it is suggested that the optimum content of OMMT is 3%–4%.