Engineering Application Research Research Articles

Research and Application of Coal Seam Permeability Improvement Technology by Sectional Directional Hydraulic Fracturing

To address the challenging issue of gas control in the working faces of the Hegang mining area, based on segmented directional hydraulic fracturing technology, ABAQUS simulation software was employed to simulate and analyze the fracturing process of coal-rock masses under the action of segmented hydraulic fracturing. The study focused on the engineering application research within the mining roadway of the 23# coal seam in the Junde Coal Mine, China. The results indicate that the numerical simulation analysis reveals elliptical patterns in the stress, strain, and fracture width variation of the coal-rock masses influenced by the fracturing action. The width of the fractures exhibits a periodic variation pattern, initially increasing and then slightly decreasing with the injection of water pressure. Additionally, each successive variation shows a decreasing magnitude. After applying segmented hydraulic fracturing technology, the average gas extraction concentration increased by a maximum of 1.73 times, the average mixed flow rate increased by a maximum of 2.16 times, and the average gas extraction pure quantity increased by a maximum of 3.10 times. Segmented hydraulic fracturing can effectively improve gas extraction efficiency, reduce coal seam gas content, and have a depressurizing effect on coal-rock layers. The research findings provide new means for safe and efficient coal mining, particularly in enhancing gas extraction efficiency, alleviating strata pressure, and preventing gas disasters.

Low-cost architecture performance evaluation strategy based on pixel difference degree contrast measurement

The time and effort required to manually design deep neural architectures is extremely high, which has led to the development of neural architecture search technology as an automatic architecture design method. However, the neural architecture search convergence process is slow and expensive, and the process requires training a large number of candidate architectures to get the final result. If the final accuracy of an architecture can be predicted from its initial state, this problem can be greatly alleviated. Therefore, this paper proposes a low-cost architecture performance evaluation strategy based on pixel difference degree contrast measurement, which takes 1) the difference matrix value between the feature map generated in the untrained architecture and the original image, and 2) the predicted accuracy of the neural network as evaluation indices. A new multi-index weight comprehensive measurement strategy was introduced to comprehensively score the multi-index, the real architecture performance can be approximately represented by score, which greatly reduces the cost of architecture evaluation. The experimental show that the proposed scoring strategy is highly correlated with real architecture accuracy. In the practical engineering application research, this strategy can search a high-performance architecture with an accuracy of 96.2% within 343.3 s, which proves that the proposed strategy can significantly improve the search efficiency in practical applications, reduce the subjectivity of artificial architecture design, and promote the application of practical time-consuming projects.

Dynamics simulation of folding wing UAVs launched from a high-altitude balloon platform

It is a new application of the high-altitude balloon system to launch multiple small folding wing unmanned aerial vehicles (UAVs). Based on the design of the launching system, we conduct numerical simulations of the ejection process from the balloon platform and the subsequent UAV wing deployment with trajectory leveling operation. We use the Kane method to establish the dynamic model of the balloon launching platform in the inertial coordinate system (ICS). By introducing the degree of freedom of UAV sliding along the sliding track, we realize the dynamic simulation of eight UAV launching processes and obtain the instantaneous separated states. The folding wing UAV first deploys its wings after ejection, which has the coupling characteristics between structural deformation and attitude adjustment. It is regarded as a multi-rigid body connecting structure composed of the fuselage and four wings. We establish the dynamic simulation model by the Kane method in the UAV body coordinate system (BCS). The Radau pseudo-spectral method is used to calculate the flight trajectory of each UAV. This paper is an engineering application research and can provide a simulation reference for the launching test of the balloon-borne folding wing UAV program.

The Application of Microtremor Exploration Technology in Thick Loess Area of Lanzhou

For the large thickness loess area in Lanzhou, engineering application research on excavated off-set loess using microtremor exploration technology. In this paper, by detecting the surface wave velocity structure of a single point, comparing the dispersion curve data of a single point with the borehole data, and comparing the surface wave velocity profile data with the engineering geological profile, the judgment basis of soil-rock interface and strong-medium interface is put forward. The stratigraphic structure of the loess area with large thickness is accurately divided; By analysing the relationship between the surface wave value of the borehole and the physical and mechanical indexes of the soil, the relationship curves of surface wave-porosity ratio, surface wave-density and surface wave-collapsibility coefficient are studied, and the fitting curves of each curve are obtained and the correlation is summarized. Through the research of this paper, it has certain guiding significance for the application of microtremor exploration in large thickness loess area.

Research on the application of improved NSGA-II in the structure design of wind turbine blade spar cap

Introduction: The blade is one of the most important parts of a wind turbine. Blade design is a complicated process involving many design links and mutual couplings. To efficiently obtain the Pareto Front and optimal blade, a novel methodology combined the improved NSGA-II with Thin-Walled Beam Theory and Classic Laminated Theory has been developed.Methods: In the optimization study, the design parameters are the thickness distribution of the spar cap and a parametric model based on blade production process is developed. The objective function is on the minimization of mass and the maximization of flap-wise stiffness. As a practical engineering application research, a 15 MW wind turbine IEA-15-240-RWT developed by NREL is used as a reference model.Results: Laws on the number of variables, blade profiles, design loads and natural frequencies present in the design have been studied through Pareto fronts obtained from multi-objective optimization results.Discussion: These laws have important implications for practical engineering design work. Meanwhile, the results show that the new methodology is effective for blade structure design, and that this approach can be easily extended to study the design of influence laws for more design parameters or more complex blade design problems.

Construction and Application of an Intelligent Roof Stability Evaluation System for the Roof-Cutting Non-Pillar Mining Method

In order to sustainably use coal resources and reduce coal mine accidents, the stability evaluation of roadway roofs is particularly important. The existing methods of roof stability evaluation and control application are greatly disjointed, the relationship between roof stability evaluation and early warning control is ignored, and an intelligent evaluation and calculation control system is lacking. Based on the successful application of the roof-cutting non-pillar mining method in various engineering geology and mining conditions, the roof stability evaluation system, mobile intelligent computing system, and engineering application research are carried out. An evaluation index system for roof stability in the roof-cutting non-pillar mining method is established, including the roof rock integrity and the roof-surrounding rock displacement. A comprehensive evaluation method for roof stability grades is proposed based on the coupling of evaluation index grading criteria and improved analytic hierarchy process (AHP) weight assignment. A handheld mobile intelligent platform for roof stability evaluation, roof hazard zone, and control suggestion is developed. The research results have been applied in the coal mine of Hecaogou with good outcomes. This intelligent stability evaluation system will provide an economical and effective approach to achieving sustainable use of coal resources.

Experimental Research on a Solar Energy Phase Change Heat Storage Heating System Applied in the Rural Area

Thermal energy storage technology can effectively promote the clean heating policy in northern China. Therefore, phase-change heat storage heating technology has been widely studied, both theoretically and experimentally, but there is still a lack of engineering application research. According to the characteristics of heating load in northern rural areas, a kind of solar heating system using phase-change materials (PCMs) for heat storage is proposed. Furthermore, a farmhouse is used to demonstrate the practical engineering applications of the heating system. The heating system consists of the phase-change heat storage device (PCHSD), solar thermal panels, and a floor radiant heating terminal, which can realize the effective utilization of solar energy. Considering solar power generation capacity, heating load characteristics of farm buildings, and the local electricity price model, four potential operation modes of the heating system are established. Then, the corresponding control strategies are proposed for the four operating modes. The actual operation data of the heating system under different operating modes were collected continuously, and the application effect of the heating system was evaluated from the aspects of thermal efficiency of the device, the renewable energy efficiency, thermal comfort level, and economy. The experimental results show that: (1) The thermal efficiency of the device is mainly affected by the heating load, which can reach more than 80% during the test period; (2) the renewable energy efficiency of the system is positively correlated with the solar radiation intensity, and the maximum can reach 100% when the solar radiation is sufficient; (3) the system maintains excellent thermal comfort in all conditions, with the average and the highest thermal comfort time accounting for 80% and 100%, respectively; (4) compared with the average level of existing clean heating technology, the annual operating cost of the system is reduced by 27.3%, and the economy is significant. The results show that the system achieves effective performance during the test period.

Multifunctional properties and applications of ultra-light porous metal materials

Porous metallic material is a new type of material with a special structure, which undergoes structural changes under certain conditions, thus forming a new structural unit. Due to their unique porosity and pore size structure, ultralight porous metallic materials have unique multifunctional properties, such as absorption and buffering of vibration energy, energy absorption and weight reduction, thermal insulation, vibration and noise reduction, and tunable performance, and thus are widely used in aerospace, energy industry, transportation, and biomedical fields. This paper reviews the research progress of ultra-light porous metal materials at home and abroad in recent years, including the basic structure and main properties of ultra-light porous metal materials, and discusses their application fields. Although China started late in this field, it has taken a place in the international arena with the continuous research work. In the future, we should focus on basic research and engineering application research to lay a solid foundation for China to achieve technological breakthrough in this field.

Numerical Simulation of Hydraulic Fracturing and Penetration Law in Continental Shale Reservoirs

The vertical heterogeneity of continental shale reservoirs is strong, the difference between lithology and stress between layers is large, the weak interface between layers develops, and the hydraulic fracture penetration and expansion are difficult, resulting in poor fracturing transformation effect. In view of this, based on the finite element and cohesive element method, this paper established a fluid-solid coupling model for the hydraulic fracture propagation through the continental shale and studied the control mechanism and influence law of various geological and engineering parameters on the hydraulic fracture propagation through the continental shale reservoir using single factor and orthogonal test analysis methods. Interfacial cementation strength between high layers, high vertical stress difference, low interlaminar stress difference, low tensile strength difference, low elastic modulus difference, high pressure fracturing fluid viscosity, and high injection displacement are conducive to the penetration and expansion of hydraulic fractures. The primary and secondary order of influence degree of each factor is: interlaminar interface cementation strength > interlaminar stress difference/tensile strength difference > fracturing fluid viscosity/injection displacement > vertical stress difference > elastic modulus. In addition, engineering application research has also been carried out, and it is recommended that the injection displacement during early construction should not be less than 3 m3/min, and the fracturing viscosity should not be less than 45 mPa·s. The field application effect is good, which verifies the engineering application value of the model.

Dynamics simulation of a folding wing unmanned aerial vehicle with the parachute system assisted launching

This paper mainly focuses on a series of dynamic problems caused by a small folding wing Unmanned Aerial Vehicle (UAV) with a parachute system assisted launched from the high-altitude balloon platform. The simulation contents are the four-stage motion processes of the “parachute-UAV system” after separation from the balloon platform, including the straightening stage, the inflation process, the stable descend under the influence of the wing deployment action, and the trajectory leveling of the UAV. The “parachute-UAV system” is equivalent to a multi rigid body connection structure. We introduce the straightening length parameter and the wing deployment angles based on the Kane method to establish the dynamic model. And we choose the inflation time method to simulate the parachute deployment process and the flat plate high angle of attack model to describe the wing aerodynamic force. In the simulation, we compare six launching processes of different wing deployment time periods and obtain the separation state of each UAV when cut from the parachute. We adopt the Radau Pseudo-Spectral method to calculate the leveling trajectory of six UAVs. This paper is an engineering application research study and can provide a simulation reference for the launching test of the balloon-borne folding wing UAV system.

Effect of fin number on the melting phase change in a horizontal finned shell-and-tube thermal energy storage unit

This paper studies the enhanced heat transfer of adding longitudinal fins in a horizontal shell-and-tube heat storage unit. A two-dimensional numerical model is established and validated through comparing with experimental data in literature. Under the same ratio of fin volume to phase change materials (PCMs), the melting thermal performance is optimized by changing the fin thickness, interval and the number. Results demonstrate that adding longitudinal fins is a simple and effective method to enhance the thermal energy storage efficiency. The number of fins greatly affects the complete melting time, and the maximum time difference caused by the number of fins is as high as 72.85% under the same phase change material (PCM) filling mass. At the same time, increasing the number of fins will weaken the local natural convection. In this paper, the optimal number of fins in the limited research range is given, and the effectiveness of longitudinal fins in improving melting speed is quantified, which has certain practical significance for the engineering application research of phase change energy storage. • Optimal number of fins is given in a horizontal finned thermal energy storage unit. • Melting time can maximally be saved as high as 72.85% by increasing fin number. • Blindly increasing fin numbers cannot further improve the energy storage speed. • Heat conduction plays a leading role in paraffin melting process for a finned TES application.

New One-Dimensional Search Iteration Algorithm and Engineering Application

In structural optimization design, obtaining the optimal solution of the objective function is the key to optimal design, and one-dimensional search is one of the important methods for function optimization. The Golden Section method is the main method of one-dimensional search, which has better convergence and stability. Based on the solution of the Golden Section method, this paper proposes an efficient one-dimensional search algorithm, which has the advantages of fast convergence and good stability. An objective function calculation formula is introduced to compare and analyse this method with the Golden Section method, Newton method, and Fibonacci method. It is concluded that when the accuracy is set to 0.1, the new algorithm needs 3 iterations to obtain the target value. The Golden Section method takes 11 iterations, and the Fibonacci method requires 11 iterations. The Newton method cannot obtain the target value. When the accuracy is set to 0.01, the number of iterations of the new method is still the least. The optimized design of the T-section beam is introduced for engineering application research. When the accuracy is set to 0.1, the new method needs 3 iterations to obtain the target value and the Golden Section method requires 13 iterations. When the accuracy is set to 0.01, the new method requires 4 iterations and the Golden Section method requires 18 iterations. The new method has significant advantages in the one-dimensional search optimization problem.

Research on numerical simulation and intelligent computing of vehicle wading driving by smooth particle hydrodynamics method

The method based on Smooth Particle Hydrodynamics (SPH) is a meshless method which is widely used at present. Its advantage is that it can effectively improve the mesh distortion when finite element is used to deal with large deformation, and its particle characteristics are suitable to deal with the simulation problem of fluid. Based on the actual vehicle wading test site and the actual parameters of the vehicle, combined with the actual situation and theoretical basis, the SPH method is used for numerical simulation analysis of the vehicle wading problem. By comparing the simulation process with the actual water changes during wading, the feasibility of using SPH method in vehicle wading application is proved. In the simulation process of vehicle wading driving, under the condition of constant water level, by setting different wading speeds of vehicle, the flow law and change mechanism of water free surface are analyzed, which are of great significance in theoretical research and engineering application research.

Novel Hydraulic Turbine Governing System Based on Digital Cartridge Valve Technology

Digital cartridge governor, as a new direction of hydraulic turbine governor control, has been applied in engineering practice, but its relative theory and engineering application research are few. The engineering application of novel hydraulic turbine governing system based on digital cartridge valve technology is taken as the research object in this paper. Combining theory with engineering application, control strategies and rules of the digital cartridge turbine governor in key concerns of engineering applications such as closed-loop power regulation, isolated grid operation, the low-frequency de-excitation and the over-speed of load rejection of bulb turbine units are discussed, and engineering applications of digital cartridge turbine governor are summarized, which can be used for reference to solve some problems in the application of governor.

Study on Optimization for High Lift Devices of Civil Aircraft Based on Rapid Calculation Method

For the requirements of aircraft high lift device design, sorts out the key links of aerodynamic calculation, optimization design process and optimization strategy selection required for the parameters optimization. By selecting accurate and efficient calculation and analysis software, compiling high lift devices 3D model forming program and calculation analysis software pre-processing program, engineering application research of aerodynamic characteristic analysis software and the establishment of calculation analysis platform are carried out. Combined with the optimization software to establish the optimization process and define the optimization objectives and constraints, the optimization design platform for the parameters of the civil aircraft high lift device based on the multi-control section and multi-airfoil is realized. The optimization results of the calculation examples are in good agreement with the wind tunnel test results, which provide guarantee for the parameters optimization of the high lift devices of civil aircraft.

Engineering application research on reliability prediction of the combined DC-DC power supply

The combined DC-DC power supply is widely used in communication, aerospace and other fields because of its low power consumption, high efficiency, small volume, high reliability, modularization and so on. As the core component of power electronic system, its reliability prediction research has far-reaching practical significance. In this paper, the engineering application of reliability prediction is studied based on a combined DC-DC power supply of 17.2 kW. The prediction of the basic reliability based on “life profile” and the mission reliability based on “mission-profile” are studied. The block diagrams of basic reliability and mission reliability are established, respectively. The MTBF is 31,699 h, which is more than three times of the required value of the power supply. The reliability of the power supply for 1 h can reach 99.999%. The reliability prediction of the two aspects has practical guiding significance for the reliability distribution and reliability growth of the project, and can also be used as reference for the reliability work of other projects.

Failure Characteristics and Control Technology of Surrounding Rock in Deep Coal Seam Roadway with Large Dip Angle under the Influence of Weak Structural Plane

In view of the unsymmetrical large deformation and failure phenomenon that often occurs after the excavation and support of the roadway in steep seam with weak structural plane, the numerical simulation analysis and engineering application research on the deformation and failure characteristics of its surrounding rock are carried out. The results show that the key position of asymmetric deformation is near the weak structural plane and the intersection of the roadway section and the inclined direction of the rock. On this basis, the “unsymmetrical high prestress pressure relief coupling control technology” is put forward, and the industrial test is carried out. The practice shows that the unsymmetrical coupling support technology can not only effectively solve the differential deformation of the surrounding rock but also ensure the coordinated deformation of the support structure and the surrounding rock, thus improving the overall stability of the roadway, greatly reducing the repair rate of the roadway, and saving the support cost.

Engineering Application Research of the Wet Processing Produced Buton Rock Modified Asphalt in Anhui Province, China

Engineering Application Research of the Wet Processing Produced Buton Rock Modified Asphalt in Anhui Province, China

Visualizing the Knowledge Structure and Research Evolution of Infrared Detection Technology Studies

This paper aims to explore the current status, research trends and hotspots related to the field of infrared detection technology through bibliometric analysis and visualization techniques based on the Science Citation Index Expanded (SCIE) and Social Sciences Citation Index (SSCI) articles published between 1990 and 2018 using the VOSviewer and Citespace software tools. Based on our analysis, we first present the spatiotemporal distribution of the literature related to infrared detection technology, including annual publications, origin country/region, main research organization, and source publications. Then, we report the main subject categories involved in infrared detection technology. Furthermore, we adopt literature cocitation, author cocitation, keyword co-occurrence and timeline visualization analyses to visually explore the research fronts and trends, and present the evolution of infrared detection technology research. The results show that China, the USA and Italy are the three most active countries in infrared detection technology research and that the Centre National de la Recherche Scientifique has the largest number of publications among related organizations. The most prominent research hotspots in the past five years are vibration thermal imaging, pulse thermal imaging, photonic crystals, skin temperature, remote sensing technology, and detection of delamination defects in concrete. The trend of future research on infrared detection technology is from qualitative to quantitative research development, engineering application research and infrared detection technology combined with other detection techniques. The proposed approach based on the scientific knowledge graph analysis can be used to establish reference information and a research basis for application and development of methods in the domain of infrared detection technology studies.

Study on the Lumped Evaluation Model of Sliding Electrical Contact Performance of Railgun

The sliding electrical contact performance of electromagnetic railgun is the main factor affecting the launch accuracy, launch efficiency, and working life of electromagnetic railguns. The research on the evaluation of sliding electrical contact performance of electromagnetic railgun is crucial for the research of electromagnetic railgun theory and engineering design. In this paper, a lumped evaluation model based on the normalized index of the resistance heat loss and frictional resistance loss of the electromagnetic railgun armature–rail interface is established, and the actual launch test of a certain launcher is evaluated to verify the lumped evaluation model. It can provide a reference for the theoretical and engineering application research of the sliding electromagnetic contact performance of the subsequent electromagnetic railgun.