Journal of Northeastern University(Natural Science)

Event Triggering Control of TCP/AQM Network System with Input Saturation

JING Yuan-wei， LIU Yan-tong， XIE Hai-xiu

2022, 43 (12): 1673-1679. DOI: 10.12068/j.issn.1005-3026.2022.12.001

Abstract ( 570 )

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The TCP/AQM network congestion control problem with user datagram protocol(UDP) data flow interference and uncertain terms is dealt with. Firstly， the problem of input saturation due to the range of packet loss rate is considered to limit the packet loss rate. Secondly， the fuzzy approximation method is used to deal with the interference and uncertain items in the system. In order to save network resources， an event trigger mechanism is introduced. Combining the input saturation， the fuzzy approximation and Backstepping technology， an active queue management algorithm is proposed， which can not only track the queue length to the expected queue length， but also reduce the numbers of triggers and save network resources. Finally， simulation verification and analysis show the effectiveness and superiority of the proposed method.

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Passive Control of Singularly Perturbed Bilinear Systems with Input Saturation

ZHANG Xiu-hua， REN Jia-xu

2022, 43 (12): 1680-1687. DOI: 10.12068/j.issn.1005-3026.2022.12.002

Abstract ( 470 )

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For singularly perturbed bilinear systems with input constraints and time-varying delays， a design method of state feedback passive controller is proposed to eliminate the effects of delay factors and input saturation on the closed-loop system. Firstly， in the framework of Lyapunov stability theory and passivity theory， using linear matrix inequality technology and convex combination technology， the design of the system state feedback controller is reduced to solve a set of linear matrix inequalities independent of the upper bound of time delay. The obtained controller makes the closed-loop system asymptotically stable and passive， and constructs the estimation of the elliptic domain of attraction related to singular perturbation parameters. The above method is extended to the system without time delay and external input. Then， a convex optimization problem is proposed to obtain the maximum estimation of the domain of attraction of the closed-loop system， and the stability bound of singular perturbation parameter is also one of the design objectives. Finally， numerical simulation examples illustrate the effectiveness of the proposed theoretical method.

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Feedback Control of Crystal Characteristics Based on Deep Learning Image Analysis

WANG Liang-yong， ZHU Yao-long， GAN Chen-yang

2022, 43 (12): 1688-1693. DOI: 10.12068/j.issn.1005-3026.2022.12.003

Abstract ( 545 )

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Aiming at the online control of crystal size expectation and standard deviation characteristics， an online feedback control method based on deep learning image analysis is proposed. Firstly， the crystal image analysis method using deep learning neural network is introduced to analyze the shape and size of crystals online. Then， mathematical statistical analysis is performed to obtain the size expectation and standard deviation of a certain batch of crystals. Finally， a feedback controller combining path tracking algorithm and PID algorithm is designed to deal with under-input characteristics， so that the target size expectation and standard deviation is obtained. The effectiveness and feasibility of the proposed method is verified by the alum cooling crystallization experiment.

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Preparation of Porous Ordered Films of In₂O₃ and Its Gas Sensitive Characteristics to Butanone

YUAN Zhen-yu， GUO Zhong-ming， FENG Yi-chao， LI Ze-yu

2022, 43 (12): 1694-1701. DOI: 10.12068/j.issn.1005-3026.2022.12.004

Abstract ( 383 )

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Monolayer and bilayer porous ordered gas sensitive films of In₂O₃ were prepared by gas/liquid interfacial self-assembly method and solution impregnation transfer method， and the gas sensitive characteristics of the films were tested. At the same time， coupling of multiple physical fields was used to simulate the gas sensitive characteristics. The results show that the gas sensitive film has regular pore structure and the pore wall is a flake structure with large specific surface area. The gas sensors based on the gas sensitive material show excellent gas sensitive characteristics to butanone. The monolayer In₂O₃ porous ordered gas sensor has a sensitivity of 15.37 to the mass fraction of 100×10^-6 butanone at the optimal operating temperature of 350℃， and the response time is only 4.3s. The sensitivity of the bilayer In₂O₃ porous ordered gas sensor to the mass fraction of 100×10^-6 butanone is 20.45， and the response time is 22.7s at the optimal operating temperature of 375℃. The simulation results are in good agreement with the test results of gas sensitive characteristics.

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A Location Privacy Protection Method Based on Secure Index

ZHANG Jing， LI Chuan-wen

2022, 43 (12): 1702-1708. DOI: 10.12068/j.issn.1005-3026.2022.12.005

Abstract ( 575 )

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Location based services(LBS)bring great convenience to people’s daily life， but also seriously threaten user’s privacy. In order to reduce user’s query cost while protecting user’s location privacy， a location privacy protection method based on secure index(LPPMSI)is proposed. LPPMSI does not need user to collect the information about data. Data owner establishes a secure index for the dummy location information. The user can retrieve the dummy location information safely and quickly， and then the server executes the LBS. At the same time， a candidate location selection algorithm based on a sliding window is proposed to reduce the computation time. The experimental results show that the LPPMSI does not require users to spend a lot of time collecting information about data distribution and query probability， under the premise that the privacy protection ability is unchanged.

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Low Sampling Rate CT Reconstruction Based on Dual Dictionary Adaptive Learning Algorithm

LUAN Feng， YANG Fan， CAI Rui-zhi， YANG Chen

2022, 43 (12): 1709-1716. DOI: 10.12068/j.issn.1005-3026.2022.12.006

Abstract ( 458 )

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In medical diagnosis， sparse sampling can reduce radiation damage to patients during CT scanning. However， direct reconstruction of sparse sampling projection data will cause distortion and artifacts in the reconstructed CT images. In order to ensure the quality of reconstructed images at low sampling rate， a dual dictionary adaptive learning algorithm is proposed， referring to the dual dictionary learning framework under the Sparse-Land model. K-SVD algorithm is combined with the dual dictionary learning algorithm framework to obtain patched projection data and FBP (filter back projection) algorithm is used to reconstruct high-quality reconstructed images. Experimental results show that the proposed method is superior to COMP double dictionary learning algorithm and MOD double dictionary learning algorithm in CT reconstruction at low sampling rate， and this method effectively improves the performance of CT image reconstruction at low sampling rate.

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Image Dehazing Algorithm Based on Attentional Feature Fusion and Dense Network

MENG Hong-ji， LIU Pei-yan， HU Zhen-wei

2022, 43 (12): 1717-1723. DOI: 10.12068/j.issn.1005-3026.2022.12.007

Abstract ( 643 )

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There are problems of distorted colors and blurred edges in the results of the state-of-the-art image dehazing algorithms. For solving the problems，an image dehazing algorithm based on deep learning is proposed. The proposed algorithm consists of two modules: attentional feature fusion module and haze model parameter estimation module. Attentional feature fusion module is designed to extract the color and edge features of hazy images sufficiently. Haze model parameter estimation module based on densely connected dilated convolution auto encoder is used to estimate the parameter of haze model and deal with the network degeneration in image dehazing. Experiments on images with thin haze and thick haze show that the proposed algorithm performs well on image dehazing， and the proposed dehazing algorithm has higher structural similarity (SSIM)， lower mean-square error (MSE)， lower edge error e_○edge than the state-of-the-art image dehazing algorithms.

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Dynamic and Kinematic Characteristics Analysis for Unloading System Under Nonlinear Vibration

ZHOU Shi-hua， WANG Yun-he， CHEN Yu， REN Zhao-hui

2022, 43 (12): 1724-1731. DOI: 10.12068/j.issn.1005-3026.2022.12.008

Abstract ( 478 )

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Aiming at the complex motion state and wear problems of the granules due to the interaction with friction and collision between the granules and the vibration of unloading surfaces， the dynamic model of the unloading system considering nonlinear vibration was proposed based on the Coulomb friction model and collision theory. The effects of excitation amplitude and stiffness ratio on dynamic characteristics， vibration transmission and flow regularity of granules were analyzed by utilizing the incremental harmonic balance method and numerical integration method. The results showed that the hardening nonlinear behavior strengthens， the multi-solution region widens， the force transmissibility decreases and the delay phenomenon appears with the increase of excitation amplitude and stiffness ratio. Different flow state of granules are observed under the same operating condition， and relative rest and forward sliding motion occur after jump and collision due to the influence of nonlinear factor of tire and suspension.

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Fault Dynamic Modeling and Simulation for Typical Components of Helicopter Main Reducers

HU Jiao， HU Niao-qing， SHEN Jian， LUO Peng

2022, 43 (12): 1732-1740. DOI: 10.12068/j.issn.1005-3026.2022.12.009

Abstract ( 521 )

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Aiming at the urgent demands of intelligent fault diagnosis for the key components of helicopter main reducers， the dynamic response characteristics of the system under the typical fault state are analyzed from the perspective of dynamic modeling， which is conducive to deepening the understanding of fault mechanism and advanced diagnosis algorithm. The fault dynamic models considering multi-nonlinear factors are developed for the typical components of a helicopter main reducer using the lumped-parameter method， and the multi-body software is applied for simulation modeling and verification. The results show that the modulation phenomenon between meshing frequency and local fault characteristic frequency is clear and the circumferential responses of the planet gear are obviously greater than the translational responses. these models can effectively reveal the vibration characteristics under typical faults and provide guidance for fault diagnosis of the helicopter transmission system.

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Damage Tolerance and Remain Fatigue Life Evaluation of Shattered Rim of EMU Wheels

CONG Tao， CHEN Gang， WU Si， ZHAO Sa

2022, 43 (12): 1740-1747. DOI: 10.12068/j.issn.1005-3026.2022.12.010

Abstract ( 709 )

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Aiming at the shattered rim crack damage of a certain type of Chinese EMU in the actual line， the failure mechanism of the shattered rim of EMU wheels was revealed on the basis of comprehensive failure analysis. Based on the test data of wheel materials’ crack propagation， combined with Franc3D simulation analysis software， the crack propagation simulation calculation was carried out for the defect. The simulation results showed that both the size and distribution of the internal defects of the wheel have an impact on the rolling contact fatigue life of the wheel. The larger the defect size， the closer the distribution position is to the maximum stress area of the wheel， and the shorter the wheel’s fatigue life. The damage tolerance of the wheel is 3mm， which is consistent with the failure criterion of 3mm in the standard. The theoretical basis of the current standard(the equivalent size of a 3mm transverse hole)for detecting the crack failure of railway wheel rim in China is given.

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Numerical Simulation and PIV Experimental Validation of Gas-Solid Two-Phase Flow in Sandblasting Machine Model

HUANG Si， Tang Zi-rui， OU Chen-xi

2022, 43 (12): 1748-1753. DOI: 10.12068/j.issn.1005-3026.2022.12.011

Abstract ( 381 )

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Particle impact inside a sandblaster is the main cause of sandblaster failure. To study the motion of the particles inside sandblasters， the EDEM-Fluent coupling method was used to analyze the characteristics of the gas-solid two-phase flow. The particle image velocimetry(PIV)method was used to obtain the particle motion inside the sandblasting tank to verify the model’s validity. The results demonstrated that after the high-speed gas enters the machine， a major vortex drives the motion of the bottom particles and gradually stabilizes in the axial section. Another vortex is generated and located in the geometric center of the horizontal plane. The particles are driven by the high-speed gas and blown up to a gradually stable height and the particle velocity is about 8% and 10% of the neighboring airflow. The local and overall errors of the simulation results and test results are less than 10%， indicating that the coupling calculation method is practical and feasible.

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Study on Laminar Flow Separation of Elliptic Airfoils at Low Reynolds Numbers

ZHANG Zhi-jun， LI Tian-ge， SI Teng-fei， SUN Ji-yu

2022, 43 (12): 1753-1760. DOI: 10.12068/j.issn.1005-3026.2022.12.012

Abstract ( 446 )

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The different relative thickness of elliptic airfoils was simulated to study the laminar flow separation and the structure of flow field in the range of low Reynolds numbers by the method of computational fluid dynamics. The results showed that a leading-edge separation bubble forms on the thin elliptical airfoil at low Reynolds numbers， which accounts for high lift coefficient and lift-drag ratio at a small angle of attack. The laminar separation bubbles gradually disappear at the leading edge and appear at the trailing edge with the increase of relative thickness. The size of the leading-edge separation bubbles of the thin elliptic airfoil gradually reduces with the increase of Reynolds numbers. However， the phenomenon of transition and reattachment disappears at lower Reynolds numbers; at the same time， the size and position of the vortex at the trailing edges of the airfoil are also greatly affected by the appearance of laminar separation bubbles. The relative thickness and Reynolds number change the aerodynamic characteristics by influencing the size and position of laminar separation bubbles on the upper surface of the elliptic airfoil and the structure of separation vortex at the trailing edge.

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Research on Three-Dimensional Ultrasonic Vibration Turning of 304 Stainless Steel with Micro-texture Tools

FANG Rui， ZOU Ping， DUAN Jing-wei， ZHANG Shuo

2022, 43 (12): 1761-1768. DOI: 10.12068/j.issn.1005-3026.2022.12.013

Abstract ( 622 )

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In order to improve the machining effect of 304 stainless steel， reduce the cutting force and prolong the tool life， a turning process combining micro-texture tools and three-dimensional ultrasonic vibration is proposed. Based on the orthogonal cutting model， the cutting force model for three-dimensional ultrasonic vibration turning of ordinary tools and micro-texture tools are established from the perspective of variable depth of cut and reduced contact area of micro-texture tools， using the friction reduction and interrupted cutting characteristics， respectively. The influence of various cutting parameters on the main cutting force was studied through the single-factor experiment of turning 304 stainless steel and comparing the tool wear. The optimal cutting parameter combination was studied through the orthogonal experiments. The results showed that compared with ordinary tools， the main cutting force of the micro-texture tool was reduced by 30%~40%; the wear degree was reduced by 11.50% on average; for reducing the cutting combined force， the best combination of cutting parameters is that the cutting depth is 0.1mm， the feed rate is 0.08mm/r， and the spindle speed is 250r/min.

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Effect of the Cooling Rate of Vacuum Centrifugal Casting on Microstructure and Mechanical Properties of 7055 Aluminum Alloy

WANG Yin， LI Yong， QIAN Xiao-ming， ZHANG Bo-si

2022, 43 (12): 1769-1776. DOI: 10.12068/j.issn.1005-3026.2022.12.014

Abstract ( 538 )

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Casting tubes of 7055 aluminum alloy were prepared by the vacuumed centrifugal casting technology. The cooling rate of the casting was changed by the addition of the tundish and the corresponding microstructure and mechanical properties of the alloys were studied. The results show that the microstructure of the casting tube sample with the slow cooling rate(Casting tube 1#) is unevenly distributed. The grains change from the equiaxed grains to the coarse dendritic ones along the solidification direction of the cross-section plane， and some second phases are distributed at the grain boundaries. However， the microstructure of the casting tube sample with the fast cooling rate(Casting tube 2#)consists of the fine equiaxed grains and a small amount of second phases. After homogenization process， the amount of second phases along the solidification direction in both samples increase gradually， and the second phases of Casting tube 1# is greater， while the hardness increment and the tensile properties of Casting tube 2# is higher.

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Effect of Grinding Media on Cyanide Leaching Behavior of Galena

ZHAO Qian-fei， TONG Lin-lin， YANG Hong-ying， JIN Rui-peng

2022, 43 (12): 1777-1783. DOI: 10.12068/j.issn.1005-3026.2022.12.015

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Using zirconia and common cast-iron grinding balls as ball milling media， the effects of grinding media on the variations of pulp and interface properties in the process of galena cyanidation was systematically investigated by chemical and analytical testing techniques. The results show that the use of ceramic ball media can reduce the consumption of NaCN compared to iron bass media， while the generation of SCN^- was reduced and the dissolved oxygen content was significantly higher. The analysis of the surface morphology and element composition of galena by scanning electron microscopy combined with energy dispersive spectroscopy(SEM-EDS)and X-ray photoelectron spectroscopy(XPS)revealed that the iron ball media resulted in more formation of oxygenated flocs of FeOOH and Fe₂(SO₄)₃ on the galena surface. In combination with the contact angle test results， it was found that the surface of galena ground with iron ball media was hydrophilic due to the adhesion of iron filings; and the increased hydrophilicity of galena due to cyanidation was not conducive to subsequent flotation recovery.

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Microcrack Propagation-Based Damage Mechanics Model of Rock

PENG Zhi-xiong， ZENG Ya-wu

2022, 43 (12): 1784-1791. DOI: 10.12068/j.issn.1005-3026.2022.12.016

Abstract ( 560 )

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Through studying the cracking and propagation law of compressive-shear cracks in rock under remote stress field， a new calculation model for the mode-I stress intensity factor at wing crack tip was proposed by considering the interaction of wing cracks. Based on the modified wing crack propagation model， considering the damage evolution on the number of the activated microcracks， a microcrack propagation-based damage model for rock was established by combining the relationship between macro-micro definition of rock damage. Finally， the theoretical curves of proposed damage model were compared with the experimental curves. The results showed that the modified wing crack propagation model can not only accurately predict the cracking angle of wing crack， but also simulate the whole range of variation of wing crack length from being extremely short to very long. The microcrack propagation-based damage model can not only continuously describe the stress-strain curves under different confining pressures， but also predict the peak strength well.

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Coupled Creep Behavior in Steel Frame-Anchor Cables-Rock and Soil Mass

GAO Xing， WANG Wei-yu， JIA Jin-qing

2022, 43 (12): 1792-1799. DOI: 10.12068/j.issn.1005-3026.2022.12.017

Abstract ( 342 )

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Through field tests， the coupled creep behavior of the steel frame-anchor cable-rock and soil mass is revealed， and the creep model and the anchoring force loss calculation model of anchor cable under the coupling effect of the support system are established. In addition， a calculation model of equivalent creep stiffness damage in the process of anchoring force loss is constructed based on the creep damage theory. The research results demonstrate that increasing the length of the anchorage section within the effective anchorage length range of the tensile anchor cable can improve its creep resistance in silty soil. Meanwhile， the compression anchor cable can effectively reduce anchoring force loss due to the expanding effect of the anchorage section. Both the steel frame-anchor cable-rock and soil mass coupled creep model and the anchoring force loss calculation model show excellent calculation results. The equivalent creep stiffness loss model can effectively predict the loss state of equivalent creep stiffness and accurately describe the attenuation law of anchoring force.

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Effect of Chemical Dust Suppressants on Suitability of Herbaceous Plants in Copper Tailings Ponds

WEI Zuo-an， XIE Jin-xin， ZHAO Jun-kang， LU Ting

2022, 43 (12): 1799-1804. DOI: 10.12068/j.issn.1005-3026.2022.12.018

Abstract ( 379 )

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To study whether spraying chemical dust suppressants in the copper tailings pond will affect plants， three kinds of plants were selected and planted in copper tailings. Water or two chemical dust suppressant solutions were sprayed regularly. The germination rate of grass seeds， the growth status of plant and root， the shear strength of root-soil complex were used as evaluation indexes to study the effects of chemical dust suppressor on the adaptability of plants. The results showed that the adaptability of the three plants to copper tailings from high to low was Ryegrass， Astragalus adsurgens and Cynodon dactylon. The plants sprayed with calcium chloride solution did not germinate. Spraying polyacrylamide can improve the adaptability of plants， and its growth is even better than the plants sprayed with water. Ryegrass sprayed with polyacrylamide solution grew the best. Therefore， it can be determined that Ryegrass is suitable for regreening of copper tailings ponds. The polyacrylamide solution can be sprayed regularly in the tailings ponds， which can not only fix soil and suppress dust， but also improve the adaptability of plants.

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