Individual Disturbance and Attraction Repulsion Strategy Enhanced Seagull Optimization for Engineering Design

The seagull optimization algorithm (SOA) is a novel swarm intelligence algorithm proposed in recent years. The algorithm has some defects in the search process. To overcome the problem of poor convergence accuracy and easy to fall into local optimality of seagull optimization algorithm, this paper proposed a new variant SOA based on individual disturbance (ID) and attraction-repulsion (AR) strategy, called IDARSOA, which employed ID to enhance the ability to jump out of local optimum and adopted AR to increase the diversity of population and make the exploration of solution space more efficient. The effectiveness of the IDARSOA has been verified using representative comprehensive benchmark functions and six practical engineering optimization problems. The experimental results show that the proposed IDARSOA has the advantages of better convergence accuracy and a strong optimization ability than the original SOA.

The Recent Progress China Has Made in the Backfill Mining Method, Part III: Practical Engineering Problems in Stope and Goaf Backfill

With the continuous innovation and development of science and technology, the mining industry has also benefited greatly and improved over time, especially in the field of backfill mining. Mining researchers are increasingly working on cutting-edge technologies, such as applying artificial intelligence to mining production. However, in addition, some problems in the actual engineering are worth people’s attention, and especially in China, such a big mining country, the actual engineering faces many problems. In recent years, Chinese mining researchers have conducted a lot of studies on practical engineering problems in the stope and goaf of backfill mining method in China, among which the three most important points are (1) Calculation problems of backfill slurry transportation; (2) Reliability analysis of backfill pipeline system; (3) Stope backfill process and technology. Therefore, this final part (Part III) will launch the research progress of China’s practical engineering problems from the above two points. Finally, we claim that Part III serves just as a guide to starting a conversation, and hope that many more experts and scholars will be interested and engage in the research of this field.

Study on Mechanical Problems of Complex Rock Mass by Composite Material Micromechanics Methods: A Literature Review

The mechanical analysis of complex rock mass is a difficult problem, which often occurs in scientific research and practical engineering. Many achievements have been made in the study of rock mass composite problems by composite material micromechanics method, but it has not been well summarized so far. This paper summarizes in detail the research status of complex rock mass problems by composite material micromechanics method at home and abroad, including the application of the Eshelby equivalent inclusion theory and self-consistent model in rock mass composite problems, and the application of the homogenization method in jointed rock mass and other rock mass composite problems such as anchored rock mass, layered rock mass, and salt rock mass with impurities. It is proposed that the structural similarity and mechanical analysis similarity should be satisfied when the composite material micromechanics method is used to study the complex rock mass. Finally, the problems that need to be further studied are put forward. The research results provide a valuable reference for the study of complex rock mass by the composite material micromechanics method.

Reutilizing Waste Iron Tailing Powders as Filler in Mortar to Realize Cement Reduction and Strength Enhancement

Recently, the massive accumulation of waste iron tailings powder (WITP) has resulted in significant environmental pollution. To solve this problem, this paper proposes an original mortar replacement (M) method to reuse waste solids and reduce cement consumption. In the experiment, the author employed an M method which replaces water, cement, and sand with WITP under constant water/cement and found that the strength development can be significantly improved. Specifically, a mortar with 20% WITP replacement can obtain a 30.95% improvement in strength development. To study the internal mechanism, we performed experiments such as thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP), and SEM. The results demonstrate that the nucleation effect and pozzolanic effect of WITP can help promote cement hydration, and MIP reveals that WITP can effectively optimize pore structure. In addition, 1 kg 20% WITP mortar reduced cement consumption by 20%, which saves 19.98% of the economic cost. Comprehensively, our approach achieves the effective utilization of WITP and provides a favorable reference for practical engineering.

Pose Determination of the Disc Cutter Holder of Shield Machine Based on Monocular Vision

The visual measurement system plays a vital role in the disc cutter changing robot of the shield machine, and its accuracy directly determines the success rate of the disc cutter grasping. However, the actual industrial environment with strong noise brings a great challenge to the pose measurement methods. The existing methods are difficult to meet the required accuracy of pose measurement based on machine vision under the disc cutter changing conditions. To solve this problem, we propose a monocular visual pose measurement method consisting of the high precision optimal solution to the PnP problem (OPnP) method and the highly robust distance matching (DM) method. First, the OPnP method is used to calculate the rough pose of the shield machine’s cutter holder, and then the DM method is used to measure its pose accurately. Simulation results show that the proposed monocular measurement method has better accuracy and robustness than the several mainstream PnP methods. The experimental results also show that the maximum error of the proposed method is 0.28° in the direction of rotation and 0.32 mm in the direction of translation, which can meet the measurement accuracy requirement of the vision system of the disc cutter changing robot in practical engineering application.

Influence of Crystalline Admixtures and Their Synergetic Combinations with Other Constituents on Autonomous Healing in Cracked Concrete—A Review

Crystalline admixtures (CAs) are new materials for promoting self-healing in concrete materials to repair concrete cracks. They have been applied to tunnel, reservoir dam, road, and bridge projects. The fundamental research and development of CAs are needed concerning their practical engineering applications. This paper reviews the current research progress of commercial CAs, including self-made CA healing cracks; the composition of CA; healing reaction mechanism; the composition of healing products; distribution characteristics of healing products; the influence of service environment and crack characteristics on the healing performance of CA; and coupling healing performance of CA with fiber, expansive agent, and superabsorbent polymers. The current research findings are summarized, and future research recommendations are provided to promote the development of high-performance cement matrix composites.

Damage detection in bridges under moving loads based on subspace projection residuals

This paper proposes a data-driven method using subspace projection residual of the responses to identify the damage locations in bridges subjected to moving loads. In this method, a moving window with a certain length determined by the sampling frequency and the fundamental frequency of the measured responses is used to cut out the acceleration responses of the bridge subjected to a moving vehicle. The characteristic subspaces of the windowed signals are subsequently extracted to calculate the local damage index using the subspace projection residual. When the window moves to the damage location, the orthogonality between the active subspace of the damaged state and the null subspace of the healthy state is invalid, which leads to a relatively large projection residual that can be used to localize the damage. To improve the reliability of the proposed approach, a one-side upper confidence limit is introduced. A simply supported beam bridge subjected to a moving mass is simulated to verify the effectiveness of the proposed method. Numerical results indicate that the proposed approach can accurately localize the single and multiple damages, even when the responses are smeared with a significant noise. Experimental tests conducted on a steel beam bridge model also demonstrate the performance and accuracy of the proposed approach. The results demonstrate that the proposed method can localize the damage even with a small number of sensors, indicating the method has a good and promising performance for practical engineering applications.

Size Effect in the Split Hopkinson Pressure Bar Experiment

For many structures, their service environment is very strict, and the requirements for the impact resistance of materials are very high. Therefore, the dynamic testing method has important scientific significance and application value for practical engineering. Split Hopkinson pressure bar (SHPB) is one of the most common experimental methods for obtaining dynamic mechanical properties of materials. However, there is no uniform standard for the size of the bars and specimens used in the test. Theoretically, the size has little influence on the experimental results, but it has not been proved by experiments. This paper mainly studies the influence of device/specimen sizes of split Hopkinson pressure bar through experiments, it is demonstrated that the sizes of bars and specimen have little effect on experimental results.

Creep Behaviour of Reinforced Concrete Beam under Long-Term Bending

Concrete structure after casting will be subjected to external load, peripheral components and other constraints, the overall performance of the structure under a long-term loading state will change continuously. In practical engineering, reinforcement is usually calculated and configured based on external load, but the role of reinforcement in the continuous loading process of concrete structure is not fully considered. Based on the elastic creep theory, this paper deduces the concrete creep calculation formula considering the influence of reinforcement, and analyses the law of the influence of reinforcement ratio and loading age on the strain and stress of concrete. The results show that the reinforcement can effectively restrain the deformation of concrete and reduce the load level of concrete.

Stiffness Degradation of Shear Wall with Frame Column and its Influence to Structural Performance

The shear wall with frame column has a wide application prospect in practical engineering for it has better ductility, bearing capacity and stiffness degradation than the shear wall with unframed column. In this paper, the finite element model of shear wall with frame column for an experiment was established in ABAQUS software firstly, Then on the base of proving the model’s precision, the axial compression ratio and the stiffness ratio of shear wall with frame column were adjusted, the influence of different axial compression ratio and stiffness ratio on the stiffness degradation coefficient was analyzed and the corresponding formulas were fitted. At last, by changing the axial compression ratio and the stiffness ratio of shear wall with frame column, The influence of stiffness degradation on the maximum displacement amplification coefficient and the bottom shear amplification coefficient were studied and the relevant formulas were fitted.