Table of Content

20 October 2023, Volume 28 Issue 5 Previous Issue   
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Machinery and Instrument
Mechanics
Mining Engineering


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Machinery and Instrument

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Calibration Technology of Optical Fiber Strain Sensor CHEN Gang(陈刚), LIU Hongyue(刘宏月), GAO Ruiriang(高瑞翔) 2023, 28 (5):  551-559.  doi: 10.1007/s12204-022-2406-9 Abstract ( 216 )   PDF (1122KB) ( 99 )   As one of the hotspots of sensing technology at present, optical fiber sensor has the characteristics of small size, anti-electromagnetic interference, and easy networking, which plays an irreplaceable role in multiphysics parameter monitoring of complex electromagnetic environments. The precise calibration of the optical fiber strain sensor has great practical value in prolonging the survival rate of the sensor, improving the measurement accuracy, and meeting the needs of long-term monitoring. By reviewing the research status of strain sensor calibration method and fiber optic strain sensor calibration method, the advantages and disadvantages of the main methods are analyzed separately from the static and dynamic perspectives, and the development prospect of the calibration technology of optic fiber strain sensor is summarized. References | Related Articles | Metrics

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High Curvature Stripe Profile Extraction Algorithm of Line Structured Light Measuring System SUN Hao (孙昊), DU Xuan (杜宣), LÜ Na(吕娜), CUI Bin(崔斌), ZHA Hui(赵辉) 2023, 28 (5):  560-568.  doi: 10.1007/s12204-022-2476-8 Abstract ( 118 )   PDF (1375KB) ( 80 )   In the line structured light measuring system, the accuracy of the process of laser stripe directly affects the measurement results. Therefore, the extraction algorithm for the laser stripe, especially the surface with high reflection and high curvature, is very important. The imaging principle of line structured light, the light intensity distribution law of laser stripe and the extraction algorithm have been studied, and a stripe profile extraction method based on real light intensity distribution has been proposed. In this algorithm, fast region of interest extraction, stripe width estimation, and adaptive filtering on the striped image are performed. Then the energy center of the stripe at the sub-pixel level is extracted. Finally, the low-quality center points are eliminated, and the context information is used to recover the missing central points. Simulated images generated based on the imaging principle of line structured light and real experimental images were used to evaluate the accuracy and repeatability of the proposed method. The results show that the method behaves excellently at the edges of high-curvature stripes; the maximum error is only 1.6 pixels, which is 1/10 of the classic Steger algorithm; the experiment repeatability is only 8.8 μm, which is 2.7 times that of the Steger method. Therefore, the proposed method improves the accuracy of object contour extraction, and it is especially suitable for contour detection of objects with high curvature. References | Related Articles | Metrics

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Measuring Transverse Relaxation Time of Xenon Atoms Based on Single Beam of Laser in Nuclear Magnetic Resonance Gyroscope ZHONG Guochen1(钟国宸),LIU Hual*(刘华), GUo Yang1(郭阳)，LI Shaoliang2(李绍良)，ZHAO Wanliang2(赵万良)，CHENG Yuxiang2(成宇翔) 2023, 28 (5):  569-576.  doi: 10.1007/s12204-022-2436-3 Abstract ( 79 )   PDF (1757KB) ( 35 )   Nuclear magnetic resonance gyroscope (NMRG) has the characteristics of high precision and miniaturization, and is one of the main applications of quantum technology in the field of navigation. The transverse relaxation time (T2) of the xenon nuclear spin in the atomic cell of the NMRG directly affects the angular random walk of the gyro. Accurate and rapid measurement of T2 is conducive to further improvement of gyroscope. At present, for the measurement of T2, the schemes of two orthogonal lasers for pumping and detecting are usually used. By applying two fast-switching orthogonal static magnetic fields and a single beam of circularly polarized laser with corresponding wavelength to pump the atomic cell, the xenon nuclear macroscopic magnetic moment Larmor precession is generated. The cesium atoms parametric magnetometer in cell is formed to detect the free induction decay signal generated by nuclear spin precession of xenon atoms. The measurement of T2 by a single laser simplifies the measurement equipment compared with traditional method with two lasers. The experimental results show that the T2 of xenon atoms is more than 10 s, and the effects of temperature are studied, which lay the foundation for the subsequent improvement of gyro performance. References | Related Articles | Metrics

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High Curvature Stripe Profile Extraction Algorithm of Line Structured Light Measuring System CHEN Qiheng1(陈启恒),PENG Na2(彭娜)，Lü Na1(吕娜)，TAO Wei(陶卫)，ZHAO Huil*(赵辉) 2023, 28 (5):  577-586.  doi: 10.1007/s12204-022-2414-9 Abstract ( 101 )   PDF (1585KB) ( 49 )   Non-uniformity of light sources is one of the inevitable error factors causing poor shape recovery accuracy of photometric stereo methods under close-range lighting with quasi point lights. Semi-calibrated photometric stereo methods are required to avoid repeated, tedious and impractical photometric calibration. In this paper, two simple, concise but effective mesh-based semi-calibrated photometric stereo methods are proposed. The proposed methods extend the traditional mesh-based photometric stereo methods and further allow joint and accurate estimation of normals and non-uniform light intensities by alternatively updating normals, depth maps and intensities. Extensive experiments are conducted to validate the effectiveness and robustness of the proposed algorithms. Even under extremely severe non-uniform lighting, the proposed methods can still suppress the error and improve the shape recovery accuracy by up to 65.6% in real-world experiments. References | Related Articles | Metrics

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Information Entropy of Angular Spectrum for Quantitatively Evaluating Eddy Current Distribution Varying in Time Domain CHEN Guolong*(陈国龙)，WANG Kang(王﹐慷),CAO Zheng (曹﹐政),JIN Wuyin(靳伍银) 2023, 28 (5):  587-595.  doi: 10.1007/s12204-022-2475-9 Abstract ( 49 )   PDF (1330KB) ( 22 )   Eddy current (EC) distribution induced by EC sensors determines the interaction between the defect in the testing specimen and the EC, so quantitatively evaluating EC distribution is crucial to the design of EC sensors. In this study, two indices based on the information entropy are proposed to evaluate the EC energy allocated in different directions. The EC vectors induced by a rotational field EC sensor varying in the time domain are evaluated by the proposed methods. Then, the evaluating results are analyzed by the principle of EC testing. It can be concluded that the two indices can effectively quantitatively evaluate the EC distributions varying in the time domain and are used to optimize the parameters of the rotational EC sensors. References | Related Articles | Metrics

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Parameter Optimization and Precision Enhancement of Dual-Coil Eddy Current Sensor ZHANG Zhenning1(张振宁)，LIU Qiang2(刘强), Lü Chunfeng3(吕春峰)，MAO Yimeil(毛义梅)，TAo Weil(陶卫),ZHAO Huil*(赵辉) 2023, 28 (5):  596-603.  doi: 10.1007/s12204-022-2511-9 Abstract ( 129 )   PDF (947KB) ( 67 )   To enhance the measurement precision of eddy current sensor in particular environments such as extreme temperature changes and limited available space in aerospace, we optimized the structural parameters of the traditional dual-coil eddy current sensor probe by electromagnetic field analysis and finite element simulation modeling, and further presented the criteria for determining the optimal coil distance of the dual-coil probe. The simulation results are verified by setting up an experimental platform. For the extreme temperature environment, the displacement measurement error caused by the full range temperature variation of the dual-coil sensor under the optimal distance is less than 21.0% of that of the single-coil sensor. On this basis, we analyzed and verified the thermal stability of the structurally optimized dual-coil eddy current sensor. After temperature compensation, the displacement measurement accuracy can reach 14.9 times more accurate than that of the single-coil sensor. The method proposed in this paper can provide a design reference for the structural optimization of the axial dual-coil eddy current sensor probe. References | Related Articles | Metrics

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Lateral Force Characteristics of Cartridge Valve Core HAN Heyong1(韩贺永),ZHANG Jianru1(张建茹), PAN Siji1(潘思意)，LI Yugui2*(李玉贵)，MA Lifeng1(马立峰),LIU Shirui3(刘实睿) 2023, 28 (5):  604-610.  doi: 10.1007/s12204-021-2402-5 Abstract ( 62 )   PDF (977KB) ( 103 )   he valve core is readily subjected to a large lateral force which affects the dynamic response speed. Here, a new type of cartridge valve core structure is proposed to solve this problem. The numerical simulation method is applied to analyze the flow characteristics of clearance flow field on velocity distribution, pressure distribution, valve core motion speed, and leakage. The results using computational fluid dynamics (CFD) show that the guide groove is set on the surface of the cartridge valve core, increasing the connecting length of the valve core, forming a uniform radial pressure distribution and velocity distribution, effectively reducing the lateral force, and at the same time ensuring that the leak is not too big. These findings provide theoretical guidance and a basis for optimizing cartridge valve to reduce the occurrence of jamming and improve the response frequency. References | Related Articles | Metrics

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CFD-Aided Investigation of Combined Flow Conditioners for Gas Ultrasonic Flow Meter YUAN Yaqi1(袁亚琦)，LI Shiyangl*(李世阳)，ZHENG Jia1(郑佳),LI Mingrui2(李明睿) 2023, 28 (5):  611-620.  doi: 10.1007/s12204-021-2378-1 Abstract ( 56 )   PDF (3396KB) ( 76 )   Stable and fully developed gas flow field is crucial for realizing accurate measurement of gas ultrasonic flow meter. To reduce the flow field distortion, a flow conditioner is usually used. However, the traditional monotype flow conditioner can only improve the flow field distribution partly. The measurement accuracy of the transit time ultrasonic flow meter is still affected because of its serious flow field distortion in the complex pipeline conditions. In this paper, to further improve the flow field distribution, a combined conditioner is investigated. The combined flow conditioner is composed of fan-shaped section, turbulent mixing cavity, and honeycomb-shaped section. The effects of fan blade angle and cavity length on the flow field of the DN50 flow meter are studied using computational fluid dynamics (CFD) simulation. Simulation results indicate that compared with the monotype conditioner, the combined conditioner has better performance on effectively reducing the swirl and turbulence and providing more stable and repetitive velocity profiles. Experiments also validate the effectiveness of the combined conditioner. The flow meter with the combined conditioner has better repeatability of less than 0.2%, which is better than those of the monotype conditioners under the same conditions. This work is very useful for accurate measurement of gas ultrasonic flow meter, especially for the complex pipeline conditions. References | Related Articles | Metrics

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Dynamic Analysis and Optimal Parameter Design of Flexible Composite Structures via Absolute Nodal Coordinate Formulation YANG Dan(杨丹),YU Haidong*(余海东)，LIN Zhangpeng(林张鹏) 2023, 28 (5):  621-629.  doi: 10.1007/s12204-022-2419-4 Abstract ( 63 )   PDF (2375KB) ( 35 )   The composite structure with the dielectric elastomer and soft materials is the main form of the actuators in soft robots. However, the theoretical model is hard to obtain due to the nonlinear large deformation of materials. In this paper, a new composite element model is established based on the absolute nodal coordinate formulation. The consistent deformation conditions at the contact interface between two thin plates are deduced. The hyperelastic constitutive model and the dielectric elastomer constitutive model are introduced for the two thin plates. Then the dynamic model is established to study the dynamic behaviors of the composite flexible structure with various parameters. The results show that the nonlinear deformation appears obviously when the flexible composite plate structure is driven by various voltages, and the warping deformation becomes more obvious with the increase of the voltage. The width and thickness of the driven thin plate influence the stability of the whole structure. With the decrease of the width or thickness, the deformation of the structure is more consistent with obvious periodicity, and the control performance is improved. Finally, the structural parameters of the composite structures are optimized to improve the control performance based on the dynamic performance. Additionally, smaller width and thickness parameters are preferred to obtain better performance in the design of flexible actuator of soft robot. References | Related Articles | Metrics

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Spectrum-Sensing Method for Arc Fault Detection in Direct Current System with Lithium Batteries HAN Zhengqian1(韩正谦)，LUO Liwenl*(罗利文)，YAo Wei2(姚伟)，YIN Shaowen2(尹邵文)，CHEN Wei2(陈伟),WANG Yinghui2(王营辉) 2023, 28 (5):  630-637.  doi: 10.1007/s12204-022-2482-x Abstract ( 81 )   PDF (1295KB) ( 38 )   We mainly study the detection of arc faults in the direct current (DC) system of lithium battery energy storage power station. Lithium battery DC systems are widely used, but traditional DC protection devices are unable to achieve adequate protection of equipment and circuits. We build an experimental platform based on an energy storage power station with lithium batteries. Then, the data collection of normal current and arc-fault current is completed under multiple conditions, and the waveforms of obvious and weak signals as the arc occurs are presented. We analyze the principles and application range of several common spectrum-sensing methods and study the feasibility of applying them to the arc detection field. Finally, the covariance absolute value detection algorithm is selected, and the average value of the current is filtered out to make the algorithm adapt to the arc detection field. The result shows that the detection probability in 500 sets of experimental data has reached 98% References | Related Articles | Metrics

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Fault Diagnosis for Rolling Element Bearing in Dataset Bias Scenario HOU Liangsheng(侯良生),ZHANG Jundong*(张均东) 2023, 28 (5):  638-651.  doi: 10.1007/s12204-021-2320-6 Abstract ( 47 )   PDF (1574KB) ( 96 )   Recently, data-driven methods, especially deep learning, outperform other methods for rolling element bearing (REB) fault diagnosis. Nevertheless, most research work assumes that REB dataset is unbiased. In the real industry applications, the dataset bias exists with REB owing to varying REB working conditions and noise interference. Recently proposed adversarial discriminative domain adaptation (ADDA) is an increasingly popular incarnation to solve dataset bias problem. However, it mainly devotes to realizing domain alignments, and ignores class-level alignments; it can cause degradation of classification performance. In this study, we propose a new REB fault diagnosis model based on improved ADDA to address dataset bias. The proposed diagnosis model realizes domain- and class-level alignments in dataset bias scenario; it consists of two feature extractors, a domain discriminator, and two label classifiers. The feature extractors and domain discriminator are trained in an adversarial manner to minimize the domain difference in feature extractors. The domain discrepancy in label classifier is reduced by minimizing correlation alignment (CORAL) loss. We evaluate the proposed model on the Case Western Reserve University (CWRU) bearing dataset and Paderborn University bearing dataset. The proposed method yields better results than other methods and has good prospects for industrial applications. References | Related Articles | Metrics

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Prediction Method of Equipment Remaining Life Based on Self-Attention Long Short-Term Memory Neural Network CAO Xiangang1,2(曹现刚)，LEI Zhuol*(雷卓)，LI Yanchuan1(李彦川), ZHANG Mengyuan1(张梦园),DUAN Xinyu1(段欣宇) 2023, 28 (5):  652-664.  doi: 10.1007/s12204-022-2506-6 Abstract ( 53 )   PDF (1771KB) ( 19 )   : Aiming at the problem of insufficient consideration of the correlation between components in the prediction of the remaining life of mechanical equipment, the method of remaining life prediction that combines the self-attention mechanism with the long short-term memory neural network (LSTM-NN) is proposed, called Self-Attention-LSTM. First, the auto-encoder is used to obtain the component-level state information; second, the state information of each component is input into the self-attention mechanism to learn the correlation between components; then, the multi-component correlation matrix is added to the LSTM input gate, and the LSTM-NN is used for life prediction. Finally, combined with the commercial modular aero-propulsion system simulation data set (C-MAPSS), the experiment was carried out and compared with the existing methods. Research results show that the proposed method can achieve better prediction accuracy and verify the feasibility of the method. References | Related Articles | Metrics

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Enhanced Tribological Performance of Diamond Films by Utilizing DLC and DLC-H Top Layers LBI Xuelin*(雷学林), YAN Ying (严莹)，ZHANG Hang(张航),LI Zizruan (李子璇), HE Yun(何云) 2023, 28 (5):  665-675.  doi: 10.1007/s12204-021-2399-9 Abstract ( 53 )   PDF (2266KB) ( 31 )   High-performance diamond films are highly demanded on tool surfaces for wire-drawing and mechanical sealing applications. Herein, this work aims at enhancing the tribological performance of chemical vapor deposition diamond films in water-lubricated conditions by utilizing non-hydrogenated and hydrogenated diamond-like carbon (DLC and DLC-H) top layers. The tribological properties of bilayer micro-crystalline diamond (MCD)/DLC, MCD/DLC-H, nano-crystalline diamond (NCD)/DLC and NCD/DLC-H films are evaluated, in terms of maximal and stable coefficients of friction (COFs), C—C bonds transformation, worn surface morphology and specific wear rates. The results show that DLC or DLC-H coated on diamond layer significantly suppresses the initial maximal COF peak and the wear of counterpart ball. Moreover, severe regular arranged sp2 C—C bonds transformation is detected on MCD film, in comparison to NCD; while inversely, the NCD/DLC bilayer exhibits severer C—C bonds transformation effect compared with the MCD/DLC. Furthermore, the DLC-H top layer shows a larger decreasing rate of maximal COFs and wear rates of counterpart balls, compared with the DLC coating, which is due to its superior self-lubricity. Among all the tested films, the NCD/DLC-H bilayer shows an optimized tribological performance. References | Related Articles | Metrics

Mechanics

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Influence of Kinematic Viscosity of Base Oil on Magnetorheological Grease WANG Wenchao (王文超), ZHANG Guang (张广),WANG Huiaing (汪辉兴)，YEXudan(叶绪丹)，WANG Jiong*(王炅) 2023, 28 (5):  676-685.  doi: 10.1007/s12204-022-2438-1 Abstract ( 45 )   PDF (1124KB) ( 27 )   In order to explore the effect of kinematic viscosity of base oil on the rheological properties of magnetorheological (MR) grease, MR grease samples containing 70% (mass fraction) carbonyl iron powder and carrier liquid separately with kinematic viscosity of 10 mm2/s, 100 mm2/s, 350 mm2/s and 500 mm2/s were prepared. The influence of kinematic viscosity of carrier liquid on the settlement performance of MR grease was analyzed. The rheological properties of MR grease were tested and analyzed under steady-state shear and oscillatory shear modes. The results show that the kinematic viscosity of base oil has a significant effect on the settling stability of MR grease. The zero-field viscosity of MR grease increases with the increase of the kinematic viscosity of the base oil, and the sedimentation performance is better. The colloid stability of MR grease is poor after the kinematic viscosity of base oil is lower than a threshold, and static oil bleed will occur immediately. In addition, the shear stress of MR grease increases with the increase of magnetic induction. When the shear rate is less than 10 s?1, the shear stress increases rapidly with the increase of shear rate. When the shear rate further increases, the shear stress tends to a stable value. The reason is that the thickener fibers in MR grease are subjected to the shear stress between laminar flows, the entanglement occurs, which makes MR grease exhibit shear thinning, and its rheological properties conform to the Herschel-Bulkley constitutive model. In the process of preparation, some carbonyl iron powder will be embedded into the thickener fiber, which shows different magnetic saturation phenomena due to shear thinning under steady-state shear and oscillatory shear. References | Related Articles | Metrics

Mining Engineering

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Prediction of Backfill Strength Based on Support Vector Regression Improved by Grey Wolf Optimization ZHANG Bo(张博)，LI Keqing (李克庆),HU Yafei(胡亚飞)，JI Kun(吉坤)，HAN Bin*(韩斌) 2023, 28 (5):  686-694.  doi: 10.1007/s12204-022-2408-7 Abstract ( 50 )   PDF (881KB) ( 17 )   In order to predict backfill strength rapidly with high accuracy and provide a new technical support for digitization and intelligentization of mine, a support vector regression (SVR) model improved by grey wolf optimization (GWO), GWO-SVR model, is established. First, GWO is used to optimize penalty term and kernel function parameter in SVR model with high accuracy based on the experimental data of uniaxial compressive strength of filling body. Subsequently, a prediction model which uses the best two parameters of best c and best g is established with the slurry density, cement dosage, ratio of artificial aggregate to tailings, and curing time taken as input factors, and uniaxial compressive strength of backfill as the output factor. The root mean square error of this GWO-SVR model in predicting backfill strength is 0.143 and the coefficient of determination is 0.983, which means that the predictive effect of this model is accurate and reliable. Compared with the original SVR model without the optimization of GWO and particle swam optimization (PSO)-SVR model, the performance of GWO-SVR model is greatly promoted. The establishment of GWO-SVR model provides a new tool for predicting backfill strength scientifically. References | Related Articles | Metrics