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30 January 2024, Volume 44 Issue 12 Previous Issue   
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Mechanical Engineering
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Study on Rheology of RBC by Coupled Model in Fluid-Solid-Electrics Multi-physical Fields HU Sheng, WANG Yang-cheng, LYU Xiao-yong 2023, 44 (12):  1673-1679.  DOI: 10.12068/j.issn.1005-3026.2023.12.001 Abstract ( 759 )   HTML ( 47)   PDF (1490KB) ( 373 )   The study of the mechanical deformation of red blood cell (RBC) suffered from fluid stress becomes more mature， but is insufficient for multi-physical fields， which involve the combination of electrical， acoustic， optical and thermal fields. Using COMSOL finite element software， a coupled model including three physical fluid-solid-electrics fields is built to study the migration simulation of two different RBC shapes with respect to spherocyte and normocyte. Compared to coupled model only involved in fluid-solid fields， the von Mises stress of spherocyte suffered from is greater than that of the normocyte when the electroosmotic flow generated by the electric field drives the cell migration. The effect of electroosmotic flow at 180μm/s leads to the RBC shape evolving into a “C” gesture. The spherocyte and normocyte have a different direction of rotation when they come across a pin obstacle due to the different shape. Regarding the coupled model with multi-physical fields presented， the motion trajectories of two cells reveal the possibility of separating different shaped cell relying on electroosmosis. References | Related Articles | Metrics

Information & Control

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Design of a Low-Order Digital Controller Based on Parametric Stability Margin LIU Dong-xu， LI Chun-hua 2023, 44 (12):  1679-1685.  DOI: 10.12068/j.issn.1005-3026.2023.12.002 Abstract ( 547 )   HTML ( 17)   PDF (729KB) ( 158 )   Most control systems in the industry contain complex uncertainty and their model parameters sometimes may fluctuate. For inaccurate identification or fluctuation of system model parameters， the set of controller parameters with the largest stability margin in the parameters stabilizing sets should be selected in order to ensure the stability of the cloosed loop system. According to the characteristic of plants in industry when they run near the operating points， the proportional-integral-derivative(PID)controller is designed based on the second-order uncertain digital control system. First of all， the PID parameters stabilizing sets composed of a family of parallel convex polygons are obtained according to the stability condition of the closed loop system. Then coordinate axes are rotated to make the convex polygons perpendicular to one of the coordinate axes. Next， the Chebyshev center and its depth of each convex polygon are obtained by making use of the linear programming method. Finally， the coordinate of the Chebyshev center with the maximum depth is selected， and its coordinate in the original coordinate system is obtained by using the inverse axis rotation transformation， which is selected as the corresponding controller parameters. References | Related Articles | Metrics

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Adaptive Hybrid Ant Colony Optimization for Capacitated Vehicle Routing Problem GU Yong， LIU Di 2023, 44 (12):  1686-1695.  DOI: 10.12068/j.issn.1005-3026.2023.12.003 Abstract ( 648 )   HTML ( 9)   PDF (1104KB) ( 289 )   To solve the capacitated vehicle routing problem (CVRP)， an adaptive hybrid ant colony optimization algorithm is proposed. A number of subroutes are obtained using ant colony optimization， and in order to enhance the ability to avoid falling into local optima， adaptive mechanisms are introduced to the rules of pheromone updating and state transferring respectively in ant colony optimization. Based on subroute combining， approximate solutions are constructed using genetic algorithm. According to the characteristics of the encoding scheme， the fitness function and genetic operators are designed to improve construction efficiency. Clarke and Wright savings algorithm is adopted to feasibilize the approximate solutions. Sweep algorithm and 2-opt local search are conducted to enhance the quality of feasible solutions. The experimental results based on standard examples show that the algorithm has good optimization accuracy and efficiency in solving the capacitated vehicle routing problem. Sensitivity analysis results show that the ant quantity has a significant impact on algorithm performance. References | Related Articles | Metrics

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Spatio-Temporal Keyword Query in Hybrid-Storage Blockchain JIANG Ji-ning， XIN Jun-chang， HAO Kun， HUANG Min5 2023, 44 (12):  1696-1704.  DOI: 10.12068/j.issn.1005-3026.2023.12.004 Abstract ( 494 )   HTML ( 16)   PDF (1816KB) ( 146 )   Hybrid-storage blockchain supports trustworthy data sharing in supply-chain with multi-party collaboration through on-chain and off-chain storage model. Aiming at the inefficiency problem caused by the existing spatio-temporal keyword query method which reads all the off-chain data in advance and adopts B+ tree as index， a spatio-temporal keyword query method in hybrid-storage blockchain is proposed. Firstly， an attribute classified blockchain model is designed， and a B2M-BKM two-level index structure is designed within and between blocks to support relational query and efficiently retrieve block data. Secondly， an on-chain and off-chain spatio-temporal keyword query method is designed to improve the queries efficiency. Finally， experiments are carried out on public data sets to verify the effectiveness of the proposed method. References | Related Articles | Metrics

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Improved Two-layer BiLSTM Electrocardiosignal Segmentation Method YANG Xuan， HE Zhan-qi 2023, 44 (12):  1705-1711.  DOI: 10.12068/j.issn.1005-3026.2023.12.005 Abstract ( 392 )   HTML ( 16)   PDF (671KB) ( 136 )   The segmentation method of ECG signals can effectively reflect athlete’s heart function and physical performance. Manual segmentation of ECG signals often consumes a lot of time and energy. In order to achieve automated ECG signal segmentation， this paper proposes improved two-layer BiLSTM electrocardiosignal segmentation algorithm， which can analyze time series forward and backward to detect and locate important waveforms such as the P-wave， QRS complex， and T-wave. The experiment used a publicly available QT database to simulate pre-competition ECG data of athletes. In comparative experiments with traditional LSTM， BiLSTM and two-layer BiLSTM， all evaluation indicators of this method have been improved. The average accuracy rate is 95.68%， the average recall rate is 91.62%， the average precision is 91.05%， the average specificity is 96.64%， and the average F1 score is 91.41%. The results showed that the proposed method has good performance in ECG signal segmentation. References | Related Articles | Metrics

Mechanical Engineering

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Reliability Analysis of Grinding Head Bolt Group System of Grinding Robot HUANG Xian-zhen， ZHANG An-xing， SUN Kai-bo 2023, 44 (12):  1712-1719.  DOI: 10.12068/j.issn.1005-3026.2023.12.006 Abstract ( 573 )   HTML ( 10)   PDF (1527KB) ( 119 )   In the whole structure connected by bolt group， the reliability of the bolt group directly affects the reliability of the whole structure. The traditional reliability analysis method of the bolt group considers that the bolt parameters are determined， but in actual working conditions， the bolt parameters are uncertain， resulting in a large error. In order to accurately evaluate the reliability of the bolts group， taking a grinding robot grinding head bolt group as an example， a finite element analysis model of the grinding head is establisted. This model is used for static analysis. The accuracy of the bolt connection finite element mesh model is verified by the bolt connection experiment. The bolt group is regarded as a system， and the influence of the bolt parameter randomness is considered. The limit state function is established based on whether the maximum stress value of the bolt exceeded the yield limit. The reliability analysis is carried out by combining the Kriging model fitting method， and then the variation rule of the system reliability with the bolt preload is explored. The results show that the reliability of the bolt system is affected by random factors and determined by multiple bolts， and decreases with the increase of the bolt preload. References | Related Articles | Metrics

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Preparation Method and Experimental Study of Array Microholes on the Surface of Nickel-Based Single Crystal Superalloy SUN Yao， TANG Ben-jia， GONG Ya-dong， LI Si-hui 2023, 44 (12):  1719-1725.  DOI: 10.12068/j.issn.1005-3026.2023.12.007 Abstract ( 476 )   HTML ( 7)   PDF (3051KB) ( 95 )   Micro hole structure has a wide range of applications in aerospace， modern medical， precision instruments and other fields， but the aperture size is small and the machining accuracy is high， and the cutting force of conventionally contact machining methods makes the hole accuracy difficult to control. However， the characteristics of non-contact and no macroscopic cutting force of EDM make it have unique advantages in the fabrication of micro holes. The experimental study on the preparation of array micro holes on the surface of nickel-based single crystal superalloy was carried out， firstly， the rhomboid array microelectrode with the average edge of less than 340μm was prepared by low speed wire electrical discharge machining (WEDM-LS) combined with finish trim cut. The forming accuracy， surface morphology and element change of the array microelectrode were further analyzed. The array microelectrode was used to process the array micro holes on the surface of nickel-based single crystal superalloy. The uniformity accuracy of the array micro holes， surface quality of the hole wall and electrode loss characteristic were investigated. The effect of cutter lifting speed and cutter lifting mode on the wall roughness of the array micro holes was revealed， which prepared array micro holes with high efficiency and high precision on nickel-based single crystal superalloy. References | Related Articles | Metrics

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Genetic Algorithm for Solving Nonlinear Equilibrium Points of Automobile Steering and Its Improvement LI Jie， JIA Chang-wang， QIAO Bin， LIU Jia-yong 2023, 44 (12):  1726-1733.  DOI: 10.12068/j.issn.1005-3026.2023.12.008 Abstract ( 379 )   HTML ( 9)   PDF (1131KB) ( 113 )   Aiming at the problem of solving nonlinear equilibrium points of automobile steering， the solving effect of the genetic algorithm was studied and an improved method was proposed. A two-degree-of-freedom model of automobile steering was established， and the reason why the nonlinear equilibrium points of automobile steering can only be solved by numerical iteration was explained， a fitness function suitable for the intelligent optimization method was constructed， and a method to determine the feasible solution range was proposed. Under the driving conditions of a vehicle speed of 70km/h， road adhesion coefficient of 0.5 and a front wheel angle of 0~0.2rad， three equilibrium points were solved by using genetic algorithm. By comparing the fitness value surfaces of large and small steering angles， the reason why the genetic algorithm can not meet the solving accuracy of small steering angle equilibrium point was explained， and the solution flow of the fusing genetic algorithm and BFGS quasi-Newton method was presented. The results show that the proposed fusion solution process can solve the small steering angle equilibrium points that meet the solving accuracy requirements and have higher solving efficiency， which makes up for the shortage of the genetic algorithm solving alone. References | Related Articles | Metrics

Resources & Civil Engineering

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Reliability Analysis of Surface Subsidence Based on Response Surface Methodology JIN Chang-yu， ZHANG Jia-yao， YU Zhong-jie， WANG Qiang 2023, 44 (12):  1734-1742.  DOI: 10.12068/j.issn.1005-3026.2023.12.009 Abstract ( 531 )   HTML ( 11)   PDF (3001KB) ( 176 )   Surface collapse induced by underground mining has become a major safety hazard in mining operations. The traditional concept of rock movement angle is still used to delineate the scope of surface collapse. The delimitation scope often deviates from the actual collapse scope. Based on the reliability index obtained by the response surface method， the calculation method of collapse area is established for improving the above problem. Firstly， the sensitivity analysis of rock mass mechanical parameters is carried out using the discrete element numerical calculation method. The parameters exhibiting strong sensitivity are selected as random variables to fit the response surface function. Then the reliability index of rock mass under different levels of degradation is calculated by MATLAB. Finally， the reliability index is used to categorize different risk levels. The proposed method is used to calculate and analyze the collapse area of Chaoyang xinhua molybdenum mine Co.，Ltd. in Liaoning Province. The numerical calculation results show that the elastic modulus， cohesion and internal friction angle of rock mass are the sensitive parameters influencing the calculation of surface collapse area. By comparing the results with the collapse area scanned by an unmanned aerial vehicle(UAV)， it has proved that the calculation method of collapse area proposed is reasonable and accurate， which can provide engineering guidance for the safety management of mining collapse areas. References | Related Articles | Metrics

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Prediction of Blasting Fragment Large Block Percentage Ratio Based on Ensemble Learning CatBoost Model JIN Chang-yu， YU Jia-qiang， WANG Qiang， CHEN Li-jun 2023, 44 (12):  1743-1750.  DOI: 10.12068/j.issn.1005-3026.2023.12.010 Abstract ( 498 )   HTML ( 6)   PDF (1729KB) ( 165 )   The problem of large block percentage ratio of blasting has always affected the production benefit of mine. The implementation of large block percentage ratio of blasting predication based on ensemble learning in machine learning is studied. Firstly， 36 groups of measured data collected from Wushan Copper Mine in Manzhouli are utilized as an example， and 10 kinds of characteristic data are sorted out. Then， the model is trained and tuned by cyclic training of the given parameters， and then the method of cross-validation grid search is used to perform secondary tuning， and the effect of the model after tuning is compared with random forest method， XGBoost model， LightGBM model， and CatBoost model. The results show that the prediction effect of CatBoost model， after two rounds of tuning， is significantly higher than that of other models. The precision rate 98.83% reaches， which proves that CatBoost model has a high prediction level after two rounds of tuning. At the same time， the feasibility of this method in the study of large block percentage ratio of blasting prediction is proved， which provides a reliable reference for blasting parameter design and large block percentage ratio of blasting optimization analysis. References | Related Articles | Metrics

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Calculation Method for Equivalent Geometric Characteristics of Hydraulic Fractures in Heterogeneous Rock Based on PHF-LSM Method LI Ming， HUANG Lei-peng， LIU Shi-yi， LIANG Li 2023, 44 (12):  1751-1758.  DOI: 10.12068/j.issn.1005-3026.2023.12.011 Abstract ( 405 )   HTML ( 13)   PDF (2153KB) ( 63 )   The permeability-based hydraulic fracture-level set method(PHF-LSM)is a smeared fracture model based on Biot consolidation theory. The model simulates the fracture development process by weakening the fracture and rock material properties in the damaged area， so the geometric characteristics of hydraulic fractures cannot be given in the solution process. According to the average effective stress field distribution during hydraulic fracture propagation， the equivalent path and equivalent height of hydraulic fracture by PHF-LSM method are established in this paper. According to the displacement field around the equivalent propagation path， the equivalent opening of hydraulic fractures is calculated， and the effectiveness of the proposed method is verified by comparing with KGD theoretical model. At the same time， the dynamic development characteristics of equivalent geometric characteristics for fractures in both homogeneous and heterogeneous rock are calculated. The results demonstrate that the established equivalent calculation method compensates for the deficiency of PHF-LSM by allowing for the determination of geometric characteristics of hydraulic fractures. References | Related Articles | Metrics

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Remote Sensing Identification Method for Open-Pit Coal Mining Area Based on Improved Faster-RCNN BAO Ni-sha， HAN Zi-song， YU Jia-xin， WEI Li-hong 2023, 44 (12):  1759-1768.  DOI: 10.12068/j.issn.1005-3026.2023.12.012 Abstract ( 373 )   HTML ( 12)   PDF (8314KB) ( 135 )   Using satellite remote sensing technology coupled with deep learning algorithms could characterize open-pit coal mining area dynamically and efficiently. This study focused on typical open-pit coal mining areas from China and other major coal-resource countries as research objects. Based on GF-2 multi-spectral remote sensing images， data sets and labels are produced to construct faster-regions with convolutional neural networks(CNN) features target recognition model. Low-resolution semantic layer and high-resolution texture information of mining area and background area were fully mined by incorporating the feature Pyramid network， which could improve faster-regions with CNN features model by optimizing parameters. The results showed that the average detection accuracy was improved to 98.48%， and the overall recognition accuracy reached 96.7%. The improved faster-regions with CNN features model efficiently increases the identification accuracy of multi-scale and multi-type open-pit mining targets in complex backgrounds. These findings can provide a scientific and accurate technical way for global energy cooperation， environmental protection， and mineral resources utilization in China. References | Related Articles | Metrics

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Influence of Wall Roughness on Slurry Flow and Particles Separation Behaviors in Spirals ZHOU Xiao-hong， GAO Shu-ling， MENG Ling-guo， ZHAO Qiang 2023, 44 (12):  1769-1777.  DOI: 10.12068/j.issn.1005-3026.2023.12.013 Abstract ( 483 )   HTML ( 8)   PDF (6100KB) ( 109 )   With the process of production， the wall roughness of spirals is not quantitative and very complex， if it is not properly controlled， the material separation effect will be seriously affected. Based on the previously established spiral flow field model and particle phase computational model， the influence of the wall roughness on the slurry flow of hematite and quartz and particle separation behaviors in 400mm spirals was systematically investigated. The simulation results show that the slurry depth， Reynolds number， and flow velocity have notable differences in radial distribution and fluctuation characteristics. With the increase of roughness， the separation fluid space significantly contracts when the roughness height reaches 0.1mm or higher. the range of laminar flow distribution expands， while the transition flow range narrows. The velocity values exhibit a clear correlation with the roughness. Higher roughness intensifies the fluctuation of the main flow and the inner circulation， leading to noticeable disruption of the inner circulation. For roughness height below 0.1mm， increasing the roughness facilitates the convergence of coarse hematite towards the inner margin， maintaining a high separation efficiency for coarse hematite and fine quartz. However， the separation efficiency decreases significantly with the further increase of roughness. The increase of roughness intensifies the distribution of fine hematite in the middle and outer regions， resulting in a substantial decrease in the separation efficiency of fine hematite and quartz. The change of particle separation behaviors is closely related to the change of flow field characteristics. References | Related Articles | Metrics

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Enhanced Mechanism of Metal Oxides on the Fire Spread of Magnesium Dust Layer CHEN Yang-yang， MENG Fan-yi， CAI Jing-zhi， YUAN Chun-miao 2023, 44 (12):  1778-1784.  DOI: 10.12068/j.issn.1005-3026.2023.12.014 Abstract ( 343 )   HTML ( 10)   PDF (4739KB) ( 97 )   Solid inerting agents that readily decompose can intensify the combustion of the magnesium dust layers. In order to explore whether metal oxides that are less prone to decomposition can inhibit the combustion of the magnesium dust layers， TiO2， MgO and CaO were used for experimental research. The results show that TiO2， MgO and CaO significantly enhance the combustion intensity of the magnesium dust layer fire spread when the mass fraction is less than 75%， and the flame phase transitions from surface heterogeneous combustion of pure magnesium dust layers to gas phase combustion. TiO2 enhanced the fire spread behavior by chemical reaction with magnesium powder， and the fire spread rate of dust layer increased by more than 50 times under the condition of perfectly reacting between TiO2 and Mg (mass fraction of 63%). MgO and CaO enhance the fire spread behavior of the magnesium dust layer by increasing the particle spacing of magnesium powder and slowing down the formation of dense oxide layer. The actual production process should pay close attention to the contact conditions of magnesium dust and metal oxides， and the research results can provide a theoretical basis for magnesium dust protection. References | Related Articles | Metrics

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Study on Process Mineralogy of Flake Graphite Ore in Ping’an County Jixi City， Heilongjiang Province WANG Nai-ling， LU Ji-wei， XU Xin-yang， JIANG Yan-xin 2023, 44 (12):  1785-1790.  DOI: 10.12068/j.issn.1005-3026.2023.12.015 Abstract ( 353 )   HTML ( 10)   PDF (8818KB) ( 84 )   To investigate the process mineralogy of the flake graphite ore in Heilongjiang province， mineral liberation analyser (MLA) was conducted to systematically study the mineral composition， particle size distribution， and dissemination characteristics of the ore based on the chemical analysis. The results showed that the percentage of the valuable element C existing in the form of graphite is 17.7% and the percentages of the primary gangue minerals feldspar and quartz are 34.32% and 20.83%， respectively. The percentage of large flake graphite whose grain size larger than 0.15mm is 46.17% and the liberation degree of graphite is 70% at 0.18mm References | Related Articles | Metrics

Management Science

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Impact of Forign Institutional Investors’ Shareholding on Corporate Social Responsibility LIU Ye， ZHANG Si-yuan， WEI Xin-li 2023, 44 (12):  1791-1797.  DOI: 10.12068/j.issn.1005-3026.2023.12.016 Abstract ( 533 )   HTML ( 6)   PDF (405KB) ( 117 )   Taking A-share listed companies in China from 2010 to 2020 as research samples， the impact of foreign institutional investors’ shareholding ratio on corporate social responsibility is explored， and internal control is used as an intermediary variable and institutional environment as a moderating variable to further verify the internal mechanism between foreign institutional investors’ shareholding ratio and corporate social responsibility. The results indicate that there is a significant positive correlation between the shareholding ratio of foreign institutional investors and corporate social responsibility， enterprises’ internal control can play a mediating role between the two， and the institutional environment has a certain moderating effect on the relationship between the shareholding ratio of foreign institutional investors and corporate social responsibility. References | Related Articles | Metrics

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Effects of Mobile Touch Devices on Cognitive Offloading for the Elderly JIN Tao， HE Jia-min， WANG Wen-rui， WU Zheng-xin 2023, 44 (12):  1798-1804.  DOI: 10.12068/j.issn.1005-3026.2023.12.017 Abstract ( 394 )   HTML ( 8)   PDF (702KB) ( 127 )   The decline of physical function and cognitive ability of the elderly affects their ability to interact with mobile devices， and optimizing the interaction of mobile devices is an effective way to reduce the cognitive burden for the elderly. Accordingly， an improved pattern copy task combined with the subjective evaluation method was used to explore the influence of the input and feedback modes of mobile touch devices on the cognitive offloading for the elderly. The results showed that the main effect of input modes is significant， and the elderly are offloaded with more working memory under the stylus condition; the main effect of the feedback modes is significant， in which the elderly are offloaded with more working memory under the combined audiovisual feedback; both input and feedback modes affect the satisfaction of the elderly， and the elderly have the highest satisfaction with the combined stylus and audiovisual feedback. It was shown that the input and feedback modes of mobile touch devices are important factors affecting the cognitive offloading for the elderly. The conclusions provide an important reference for optimizing the interaction modes of mobile touch devices and reducing the cognitive burden for the elderly. References | Related Articles | Metrics