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24 May 2023, Volume 44 Issue 5 Previous Issue   
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Materials & Metallurgy
Mechanical Engineering
Resources & Civil Engineering
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Materials & Metallurgy

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Effect of Solution Temperature on Microstructure and Mechanical Properties of Fe-20Mn-9Al-1.2C Low-Density Steel WANG Hai-tao， LI Jia-dong， DENG Xiang-tao， WANG Zhao-dong 2023, 44 (5):  609-616.  DOI: 10.12068/j.issn.1005-3026.2023.05.001 Abstract ( 797 )   HTML ( 91)   PDF (3902KB) ( 575 )   To obtain an excellent combination of strength and toughness， a new heat treatment route of low-density Fe-20Mn-9Al-1.2C steel was designed. After smelting， forging and hot rolling， the steel was treated by solid solution at 900， 950， 1000 and 1050℃， respectively for 24min and a water quenching afterward. The effect of solid solution temperature on microstructure and mechanical property of the tested steel was studied by OM， SEM， XRD， EMPA and other methods. The results show that the density of the steel is 6.826 g/cm3， which is about 13% lower than the conventional one. When the solid solution temperature is 1000℃， the comprehensive mechanical properties of the steel are the best with the tensile strength of 1065MPa， yield strength of 937MPa， elongation of 65.3%， strong strength-ductility product of 69.5 GPa·%， and impact energy(V-notch) at-40℃ of 49 J， respectively. References | Related Articles | Metrics

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Technology Development for Dynamic Tracking of Layered Burden Structure in Blast Furnace LI Hai-feng， YANG Qiao-ting， SHAO Lei， ZOU Zong-shu 2023, 44 (5):  617-625.  DOI: 10.12068/j.issn.1005-3026.2023.05.002 Abstract ( 469 )   HTML ( 24)   PDF (2414KB) ( 348 )   The burden radial distribution in blast furnace influences the profile and location of the cohesive zone formed in the lower part of blast furnace， and thus has considerable impact on process stability and fuel rate. A mathematical model for predicting the layer burden structure in blast furnace was developed and transformed into a software with friendly visual user interfaces for blast furnace operators. The software can be used to calculate the detailed information of the layered burden structure under different charging parameters. The charging parameters include charging matrix， stockline height， charging direction， and radial descending velocity profile of the burden surface. The prediction results include the radial distribution of ore-to-coke ratio， the locatin evolution of burden layers， and the change of layer thickness. These results can provide reference basis for optimization of charging operation. References | Related Articles | Metrics

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Numerical Simulation of Gas-Solid Heat Transfer and Moisture Evaporation in Preheating Shaft Kiln DUAN Shao-pei， LI Bao-kuan， MU Yong-hong， RONG Wen-jie 2023, 44 (5):  626-634.  DOI: 10.12068/j.issn.1005-3026.2023.05.003 Abstract ( 488 )   HTML ( 21)   PDF (3521KB) ( 245 )   A shrinking core model for gas-solid heat transfer and moisture evaporation is established by studying the preheating process of a new preheating shaft kiln. The gas temperature distribution， temperature distribution of mixed solid material based on ferrochrome pellets and moisture evaporation of the solid materials in the kiln are simulated and analyzed at the gas velocities of 10， 15 and 20m/s and temperature of 993K. The results show that with gas velocity of 20m/s and temperature of 993K， the solid material temperature reached above 850K and the pellets were dried， which can fulfill the temperature requirements and moisture content requirements of the material preheated. Through a reasonable preheating process， the problem of pellets bursting and affecting production safety due to high moisture content in the smelting process is prevented， and the enterprise’s goal of utilizing the waste heat of the high-temperature exhaust gas generated in the smelting process is also fulfilled. References | Related Articles | Metrics

Mechanical Engineering

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Surface Mechanical Properties of Ultrasonic Rolling Micro-forging Additive Manufactured Parts REN Zhao-hui， LI Zhu-hong， WANG Yun-he， ZHANG Zi-ting 2023, 44 (5):  634-641.  DOI: 10.12068/j.issn.1005-3026.2023.05.004 Abstract ( 614 )   HTML ( 21)   PDF (1298KB) ( 354 )   Defects such as cracks and high surface roughness are likely to occur in the additive manufacturing of Ti-6Al-4V titanium alloy parts. In order to solve this problem， the ultrasonic rolling micro-forging technology， which is applied in surface strengthening， is combined with the additive manufacturing process. The process of laser fuse additive manufacturing and cooling is simulated by the finite element software， and the effect of ultrasonic rolling micro-forging on the mechanical properties of the additive part surface is analyzed. The results show that the residual stress changes from tensile stress to compressive stress after ultrasonic rolling micro-forging， which effectively reduces the risk of defects such as cracks in additive parts. Meanwhile， the surface equivalent plastic strain and surface micro-hardness of the processed additive increase. In addition， ultrasonic rolling micro-forging has the greatest influence on the contact area of the rolling head. References | Related Articles | Metrics

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PI Control Strategy of Double-Flexible Manipulator’s Servo System LI Xiao-peng， ZHOU Sai-nan， YIN Meng， FAN Xing 2023, 44 (5):  642-651.  DOI: 10.12068/j.issn.1005-3026.2023.05.005 Abstract ( 531 )   HTML ( 22)   PDF (1942KB) ( 385 )   The load flexibility and joint flexibility in the flexible manipulator system will lead to the fluctuation of output speed， so the PI control strategy is used to control the servo system. Based on the continuum vibration theory and Lagrange equation， a dynamic model considering both the load and joint flexibilities is established， and the influence of the two flexibilities on the transmission characteristics of the system is analyzed. The Arnoldi method is used to reduce the order of transfer functions， and the error of order reduction is evaluated. The pole assignment method is used to design the controller’s parameters， and the effects of the pole damping coefficient and natural frequency on the system dynamic characteristics are discussed. Finally， the simulation analysis and rotation control experiment of the double-flexible manipulator are carried out. The results show that adjusting the controller’s parameters properly can effectively reduce the speed fluctuation of the servo drive system of the flexible manipulator， and then suppress the mechanical resonance phenomenon， so that the system tends to be more stable. References | Related Articles | Metrics

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Theoretical and Test Study of Inertial Capacitance Metamaterial Torsional Vibration Isolators ZHU Qing-dong， CHEN Ya-qiang， WU Chao， YAO Hong-liang 2023, 44 (5):  651-659.  DOI: 10.12068/j.issn.1005-3026.2023.05.006 Abstract ( 482 )   HTML ( 21)   PDF (2701KB) ( 236 )   The inertial capacitance metamaterial torsional vibration isolator is proposed to address the problem of excessive mass and volume of the current metamaterial structure in low frequency vibration suppression. Firstly， the specific structure of the inertial capacitance metamaterial vibration isolator is designed and its advantages over the conventional metamaterial vibration isolator are analyzed. Secondly， the intermediate wheel transmission mechanism is analyzed， and on the basis of the kinetic equations of the inertial capacitance metamaterial isolator， the energy band structure of the inertial capacitance metamaterial isolator and the transmission curve of the metamaterial isolation system are derived， and the influence of the diameter of the driven metal disk and the number of single cells on the vibration suppression effect of the inertial capacitance metamaterial isolator is further investigated. The effect of torsional vibration suppression of the designed inertial metamaterial isolator is verified through experiments. The results show that the maximum vibration attenuation of the designed inertial metamaterial vibration isolator can reach -60dB， which can effectively suppress the low frequency torsional vibration of the rotor system and thus meet the practical engineering requirement. References | Related Articles | Metrics

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Sommerfeld Effect of Non-ideal Vibration System Driven by AC Motor CHEN Xiao-zhe， LIU Jun-qi， ZHONG Shan， LI Ling-xuan 2023, 44 (5):  660-666.  DOI: 10.12068/j.issn.1005-3026.2023.05.007 Abstract ( 433 )   HTML ( 15)   PDF (1030KB) ( 200 )   By taking the spring mass damping system of the single degree of freedom excited by the eccentric rotor as the object， Sommerfeld effect of the non-ideal vibration system driven by the AC motor as the prime motor was studied. The electromagnetic torque formula of the AC motor was introduced to establish the dynamic model of the vibration system driven by the AC motor. Based on the small parameter averaging method， the approximate solution of the vibration system response was obtained. According to the solution， the torque balance equation of the motor in steady-state motion was derived. Numerical analysis illustrated that the angular velocity of the motor and the frequency of power will jump in the resonance region， and the relationship between the amplitude of the system and the frequency of power has hard non-linear characteristics. The mechanism of these phenomena was explained by the stability judgment conditions， and the correctness of the theoretical method was verified by the numerical time domain simulation. Finally， the key structural parameters were discussed quantitatively and qualitatively. References | Related Articles | Metrics

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Displacement Reliability Analysis of Cone Valve Spools Based on Bidirectional Fluid-Solid Coupling HUANG Xian-zhen， LUAN Xiao-gang， ZHU Li-sha， LIU Hui-zhen 2023, 44 (5):  667-673.  DOI: 10.12068/j.issn.1005-3026.2023.05.008 Abstract ( 423 )   HTML ( 14)   PDF (1145KB) ( 347 )   The traditional spool displacement stability is carried out on the premise that the system parameters are determined. However， in the process of actual production and use， various system parameters are uncertain. To solve this problem， a finite element analysis model of the cone valve’s dynamic process was established， and the dynamic response process of the cone valve under the pressure inlet was analyzed and solved by the bidirectional fluid-solid coupling and the overlapping grid method. Considering the influence of parameter randomness， the limit state equation of the spool displacement fluctuation was established based on whether the displacement after the spool stabilizes exceeds the allowable displacement. The reliability analysis of the displacement fluctuation after the stability of the spool was carried out by the Monte-Carlo method and Kriging method. It was shown that the stable displacement fluctuation range of the spool is 19% less than the theoretical value， and the reliability of the stable displacement of the spool decreases as the inlet pressure increases. References | Related Articles | Metrics

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Dynamic Modeling and Simulation of Transmission System of Cold Rolling Tension Levelers CHEN Bing， XIA Bo-ran， TANG Xiao-lei 2023, 44 (5):  674-681.  DOI: 10.12068/j.issn.1005-3026.2023.05.009 Abstract ( 397 )   HTML ( 17)   PDF (1723KB) ( 230 )   Tension levelers are widely used in the continuous production line of wide strips in modern metallurgical enterprises. The core problem of its development is the optimal matching of the power of the drive motor of the tensioning roller group arranged before and after the straightener. Based on the theory of power balance method and bond graph method， the power bond graph model of the transmission system was established. Taking the in-service differential tension straightener for the production line of cold rolling plates in a modern steel company as an example， the dynamic characteristics of power transmission were studied. The results showed that when the tension straightening drive system produces strips of different specifications， the power fluctuation probability of the main transmission motor increases at the early start-up low-speed stage， which leads to the increase of the component deformation and the decrease of the safe service probability of the equipment. The MAPE (mean absolute percentage error) of the model calculated by the field industrial test is 9.3%， which verifies the accuracy of the model. References | Related Articles | Metrics

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Point Cloud Denoising Algorithm Based on Hybrid Filtering and Improved Bilateral Filtering LIU Yong-sheng， CAI Shi-yang， CHEN Yi-xin， XU Zhi-bo 2023, 44 (5):  682-688.  DOI: 10.12068/j.issn.1005-3026.2023.05.010 Abstract ( 635 )   HTML ( 25)   PDF (2340KB) ( 465 )   The point cloud of curved parts obtained by laser scanning contains noise points， that may affect the surface fitting accuracy of the parts. A denoising and smoothing method based on noise classification was proposed. The kd tree algorithm and K-means clustering algorithm were combined to remove the outlier noise. The curvature of the sampling points was substituted to improve the bilateral filter factor， and the improved bilateral filtering algorithm was used to smooth the non-outlier noise. The proposed method was used to denoise the point cloud of the blade of the guide pulley of the hydraulic torque converter， and compared with the measurement results obtained by coordinate measuring machine. The experimental results showed that the deviations between more than 70% of the measurement points and the denoised point cloud is within ± 10μm. It was found that the proposed method can well preserve the geometric features of the scanned object， and the denoised point cloud can meet the accuracy requirements of the model reconstruction. References | Related Articles | Metrics

Resources & Civil Engineering

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Mechanical Properties of Deep Sandstone Under True Triaxial Stress WANG Zhe-chao， SHI Wei-chuan， KONG Rui， GUO Jia-fan 2023, 44 (5):  689-696.  DOI: 10.12068/j.issn.1005-3026.2023.05.011 Abstract ( 618 )   HTML ( 22)   PDF (1220KB) ( 355 )   A series of true triaxial compression tests on sandstone were carried out based on the true triaxial testing machine. The sandstone samples were taken from a gas storage facility， with a buried depth of 3600 meters. The strength and deformation characteristics of deep sandstone under true triaxial stress were studied， and the elastic modulus， cohesion， friction angle and peak failure strength of deep sandstone and shallow sandstone were compared. The results show that with the increase of the intermediate principal stress， the peak strength of the deep sandstone will also increase， the crack initiation stress and the damage stress of the deep sandstone will also increase， and the intermediate principal strain at the peak will decrease. With the increase of sandstone depth， the elastic modulus， cohesion and friction angle of sandstone all show an increasing trend. The octahedral shear stress of the peak failure strength of the shallow rock and the effective mean normal stress show a nonlinear relationship， while the octahedral shear stress of the peak failure strength of the deep rock has a linear relationship with the effective mean normal stress. And the Mogi-Coulomb criterion is more suitable for reflecting the strength characteristics of deep sandstone at failure. References | Related Articles | Metrics

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Analysis of Evolution Characteristics and Influencing Factors of Vortex Structure in Rough-Walled Fracture YANG Jin-jin， WANG Zhe-chao， QIAO Li-ping， LI Wei 2023, 44 (5):  697-704.  DOI: 10.12068/j.issn.1005-3026.2023.05.012 Abstract ( 451 )   HTML ( 14)   PDF (1119KB) ( 158 )   To study the evolution characteristics and influencing factors of vortex structure in rough-walled fracture， COMSOL Multiphysics is used to simulate the flow field under different conditions， and the meso-flow structure is visualized. Based on the response surface methodology (RSM)， a second-order polynomial regression equation is established， and the variance analysis and significance test of the regression equation are carried out， and the effect of multi-factor interaction on vortex structure is discussed. The results show that the evolution process of meso-flow structure in rough-walled fracture includes the generation， development， rupture and stability. The regression model has good significance and adaptability， which can effectively determine the significance of influencing factors. The influencing degree of multi-factor interaction on vortex structure is as follows: average aperture is the largest， followed by velocity， and roughness is the smallest. The results are of great significance to reveal the mesoscopic mechanism of nonlinear seepage in fractures. References | Related Articles | Metrics

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Bulk Rate Statistical Method Based on an Optimised Algorithm for Blasted Ore Image Segmentation MAO Ya-chun， FAN Shuo， CAO Wang， LI Shi 2023, 44 (5):  705-711.  DOI: 10.12068/j.issn.1005-3026.2023.05.013 Abstract ( 483 )   HTML ( 19)   PDF (3931KB) ( 261 )   The ore image segmentation effect is limited by factors such as lighting conditions， targets density and low contrast of edges， resulting in low statistical accuracy of the bulk rate. Anqian Mine blasted ore image was used as the data source， firstly the bilateral filtering algorithm was used to remove the feature-enhanced image noise， then the adaptive thresholding algorithm and HED (holistically-nested edge detection) algorithm were used to initially segment the ore image， and then the morphology and connectivity removal algorithm were used to remove the segmentation hole formed by the texture of the ore surface. The results were further fused and a distance-based watershed algorithm was introduced to eliminate the under-segmentation of the ore image， and finally the optimal segmentation of the ore image was achieved. The results show that the proposed method can effectively improve the accuracy of blasted ore image segmentation， achieve accurate statistics of blasting bulk rate in open pit mines， and provide technical support for intelligent evaluation of blasting effects. References | Related Articles | Metrics

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Transport Characteristics of Butyl Xanthate in Metal-Coated Quartz Sand CHENG Li， LIANG Hai-jun， NAN Xiang-li， HU En-zhu 2023, 44 (5):  712-718.  DOI: 10.12068/j.issn.1005-3026.2023.05.014 Abstract ( 404 )   HTML ( 13)   PDF (1284KB) ( 159 )   There is a combined pollution of heavy metals and residual organic agents for mineral dressing and smelting in nonferrous metal industry area. The transport behaviors of butyl xanthate (BX) in quartz sand， Fe-coated sand and Fe/Cu-coated sand were investigated using saturated sand column experiments and mathematic model. The results show that quartz sand loading Fe (0.07mg/g) on the surface can reduce the recovery rate of BX from 89.8% to 45.3%， and it decreases by 41.5% with the doubling of iron content. When CuO was loaded subsequently on the Fe-coated sand，BX could react with Cu2+ to generate CuBX. And the transport of BX was completely inhibited when Cu was loaded within a range of 0.010~0.055mg/g. References | Related Articles | Metrics

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Experimental Study on Acid Resistance Characteristics of Polyaromatic Oxadiazole Fiber MAO Ning， NIU Hui-rong， LIU Jing-xian 2023, 44 (5):  719-725.  DOI: 10.12068/j.issn.1005-3026.2023.05.015 Abstract ( 401 )   HTML ( 18)   PDF (875KB) ( 169 )   In view of the aging of polyaromatic oxadiazole (POD) fiber under the action of acid gas during high-temperature smoke and dust treatment， the POD fiber was acidified with nitric acid and sulfuric acid solution， and the change law of its breaking strength and elongation was studied. The kinetic characteristics of the thermal degradation reaction of POD fiber were analyzed by Kissinger multi-heating rate method. The results showed that the breaking strength and elongation of POD fiber decreased with the increase of acid mass fraction and time， and the maximum reduction of breaking strength under the action of nitric acid and sulfuric acid reached 57.96% and 67.29%， respectively. With the aggravation of acidification， the thermal degradation activation energy and thermal stability of POD fiber decreased. There is a quantitative relationship between breaking strength and activation energy. The activation energy of thermal degradation can be used as an indicator to quickly evaluate the acid aging degree of POD fiber. References | Related Articles | Metrics

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Study on Coal Deformation and Adsorption Stress Caused by Supercritical CO2 Adsorption WANG Lei， YANG Dong， XING Jun-wang 2023, 44 (5):  726-734.  DOI: 10.12068/j.issn.1005-3026.2023.05.016 Abstract ( 452 )   HTML ( 20)   PDF (1458KB) ( 317 )   The constant temperature adsorption of helium/supercritical CO2(SC-CO2) and deformation of coal are tested， the axial deformation and radial deformation of coal are real-time monitored， and the coal expansion deformation caused by effective stress and adsorption stress and the adsorption stress of coal to SC-CO2 are revealed. The results show that the axial strain by coal adsorption of different gases is higher than the radial strain， and the variation law of coal strain caused by helium and SC-CO2 with gas injection pressure is similar. In the process of increasing the temperature， the volume strain of coal adsorbed helium increased first and then decreased， while the volume strain of coal adsorbed SC-CO2 gradually decreased. With the increase of temperature， the deformation of coal during the adsorption of SC-CO2 gradually changed from the deformation caused by adsorption stress to the deformation caused by effective stress. The ratio of the volume strain of adsorption stress to the volume strain of effective stress is gradually decreased. The adsorption stress of coal to SC-CO2 decreases with the increase of temperature. When the temperature increases from 60℃ to 80℃， the adsorption stress only decreases by 29%. At the same time， the ratio of SC-CO2 adsorption stress to gas adsorption stress reaches the maximum at 60 ℃， and the SC-CO2 has the best gas displacement effect at this temperature. References | Related Articles | Metrics

Management Science

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Research on Relationship Between Information Efficiency and Liquidity Premium JIN Xiu， HOU Yu-ting 2023, 44 (5):  735-742.  DOI: 10.12068/j.issn.1005-3026.2023.05.017 Abstract ( 579 )   HTML ( 16)   PDF (459KB) ( 154 )   The relationship between information and liquidity premium is studied from the dimension of information efficiency， and verified from the perspective of institutional shareholding ratios. Then the impact of market liquidity shock on their relationship is further discussed. It is found that there is an obvious liquidity premium in Chinese stock market， the liquidity premium is higher under low information efficiency and the stocks with low institutional shareholding ratios show higher liquidity premium due to low information efficiency， and under the impact of market liquidity， the liquidity premium increases by leaps under the condition of low information efficiency， and the relationship between information efficiency and liquidity premium is significantly enhanced. The research conclusion has a certain theoretical value for improving and enriching the research on the relationship between information and liquidity premium， and provides a valuable reference for investors to allocate portfolios in line with their own risk preferences and regulators to supervise the market. References | Related Articles | Metrics

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Study on Spatio-Temporal Evolution and Influencing Factors of Development Intensity in Shenyang’s Five Districts GAO Yan-peng， CHEN Wen-jun 2023, 44 (5):  743-751.  DOI: 10.12068/j.issn.1005-3026.2023.05.018 Abstract ( 447 )   HTML ( 16)   PDF (2560KB) ( 155 )   A development intensity model was constructed to explore the spatio-temporal evolution of development intensity of Shenyang’s five districts from 2005 to 2020 and its influencing factors. The results showed that: the development intensity shows a trend of rapid decline at first and then steady development. After 2009， due to the influence of policy regulation， the development activities tend to be more reasonable， which have also led to a gradual reduction in regional differences. The spatial pattern of development intensity is high in the center and low in the periphery and is characterized by circular development. The spatial agglomeration of development intensity is obvious， showing the“core-edge”characteristics of hot spots agglomeration in the central regions and cold spots agglomeration in the edges. Per capita urban and rural land area， elastic growth coefficient of urban land and average land GDP are the main factors affecting the development intensity. References | Related Articles | Metrics

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Research on Car Sales Prediction Based on Online Reviews and Internet Search WANG Shu-tian， LIN Yan， ZHU Guo-qing， YAN Ye-jin 2023, 44 (5):  752-760.  DOI: 10.12068/j.issn.1005-3026.2023.05.019 Abstract ( 708 )   HTML ( 20)   PDF (1877KB) ( 419 )   The emotion analysis algorithm is used to obtain the valence of online reviews， and the prospect theory and entropy method are used to adjust the valence of online reviews. Combined with the volume of reviews and Internet search data， an autoregressive distributed lag model is established to predict and analyze the sales volume of cars in different price levels. It is shown that the prediction effect of the model， which takes into account the valence， volume of online reviews and Internet search data affected by negative information， is better than that of the traditional model and more consistent with actual situations. However， there are differences in the prediction effect for cars of different price levels. The sales prediction of low-end cars is the best， followed by mid-range cars， and finally high-end cars. References | Related Articles | Metrics