Journal of Northeastern University(Natural Science)

Efficient Joint Detection and Defense Mechanism for DDoS Attack in SDN

ZENG Rong-fei， GAO Yuan， WANG Xing-wei， ZHANG Bang

2020, 41 (9): 1217-1222. DOI: 10.12068/j.issn.1005-3026.2020.09.001

Abstract ( 935 )

HTML

PDF (1020KB) ( 799 )

In order to defend against the DDoS attacks for SDN(software-defined networking) controller， this paper proposed an efficient joint detection and defense mechanism. The joint detection part adopted the combination of improved self-organizing mapping algorithm and multidimensional conditional entropy algorithm. By combining the two methods， the purpose of joint detection was achieved. The joint defense part includes a conventional defense module and a fast defense module， which adopts different defense strategies for different detection results by adjusting the priority. Extensive experimental results showed that the joint detection mechanism can achieve a detection rate of 95.2%， and the response time of the joint defense mechanism to the controller can be reduced by 0.11s on average， compared with the single defense mechanism.

References | Related Articles | Metrics

Improved Load Re-allocation Strategy Based on Maximum Residual Capacity of Node

WANG Li-fu， LI Huan， ZHAO Guo-tao

2020, 41 (9): 1223-1230. DOI: 10.12068/j.issn.1005-3026.2020.09.002

Abstract ( 723 )

HTML

PDF (808KB) ( 745 )

When a node in the network fails， in order to study how the node load is distributed to the connected nodes to maintain the normal operation of the network， in this paper， a load re-allocation strategy based on the maximum residual capacity of neighbor nodes was proposed. When the fault node distributes the load， the residual capacity of the receiving node was taken into account， so as to avoid the propagation of the fault caused by full load and overload after the node received the additional load. Considering the energy consumption in the process of load propagation， the influence of path length on load distribution was analyzed. Through the simulation of the model network， the influence of tolerance parameters， load distribution parameters and path length on the load distribution effect was analyzed. The results showed that the network could achieve the desired effect by adjusting the path adjustable parameters， and the propagation of cascade failure could be effectively prevented.

References | Related Articles | Metrics

Adaptive Threshold Image Segmentation Based on Definition Evaluation

ZHANG Tian， TIAN Yong， WANG Zi， WANG Zhao-dong

2020, 41 (9): 1231-1238. DOI: 10.12068/j.issn.1005-3026.2020.09.003

Abstract ( 1153 )

HTML

PDF (2594KB) ( 1517 )

Threshold is a widely used method for image segmentation. With the variance of the information in the image， this paper proposed a novel adaptive threshold segmentation method based on image definition evaluation. This method uses the definition evaluation function as a measure of the gray similarity change in the image after thresholding. Repeated iteration and Pearson correlation were combined until the optimal segmentation threshold was found. Test comparisons were performed using multiple sets of image data， especially low-contrast images， such as slight defects on the steel surface. The results showed that compared with the traditional threshold segmentation method and its improved algorithm， in the processing of low-contrast images， the proposed method can adaptively and accurately find a reasonable threshold value， and has an excellent performance of image segmentation.

References | Related Articles | Metrics

Modeling and Analysis of COVID-19 Based on Multi-isolation Strategy

FU Qiang， YAO Yu

2020, 41 (9): 1239-1243. DOI: 10.12068/j.issn.1005-3026.2020.09.004

Abstract ( 1120 )

HTML

PDF (491KB) ( 1343 )

Aiming at the outbreak of COVID-19 (corona virus disease 2019)， considering multi-isolation measures， a non-linear infectious disease model was established to study the trend of COVID-19. Comparing the data in China of the COVID-19 with the results of simulation experiments， the isolation measures are important for the prevention and control of COVID-19. The results showed that if the isolation measures were implemented one week later， the number of infected persons in the entire epidemic would increase almost 7 times. In addition， the measure for newly confirmed clinical cases in Hubei Province is analyzed by simulation experiments. The results showed that the measure effectively solved the problem of previously missed cases and can greatly speed up the extinction of the epidemic. Then， the subsequent official data of COVID-19 also agreed with the simulation results.

References | Related Articles | Metrics

Design and Implementation of Searchable Encryption Scheme Prototype System Based on BSSEVD

LI Peng， ZHOU Fu-cai， ZHANG Shuai

2020, 41 (9): 1244-1250. DOI: 10.12068/j.issn.1005-3026.2020.09.005

Abstract ( 691 )

HTML

PDF (499KB) ( 666 )

In order to solve the problem of high time-complexity and low efficiency of keyword search of searchable encryption scheme caused by large security index file in large data set， a scheme of Boolean symmetric searchable encryption in very-large databases (BSSEVD) was proposed. The storage structure of security index was optimized by using three-layer indirect addressing block storage， and the leakage problem caused by multi keyword Boolean search was solved by adding keyword intersection security indexes. Based on this scheme， a prototype system of searchable encryption scheme is designed and implemented， which mainly includes three modules: file preprocessing module， initialization module and keyword search module. The performance of the system was analyzed by experiments， and the experimental result showed that calculation efficiency of the scheme is significantly improved.

References | Related Articles | Metrics

High Temperature Vacuum Low-Pressure Pulse Carburizing Process of 12Cr2Ni4A Steel

TIAN Yong， AN Xiao-xue， WANG Zhao-dong， WANG Guo-dong

2020, 41 (9): 1251-1256. DOI: 10.12068/j.issn.1005-3026.2020.09.006

Abstract ( 1130 )

HTML

PDF (906KB) ( 994 )

Compared with traditional atmosphere carburizing， the high temperature vacuum carburizing has great advantages in improving carburizing efficiency， product quality and saving energy. The critical parameters of austenite grain growth behavior， diffusion coefficient， and saturation carbon concentration of austenite in 12Cr2Ni4A steel were investigated in this work. Combined with the principle of vacuum low-pressure pulse carburization， the high temperature vacuum low-pressure pulse carburizing process was verified experimentally and the parameters of carburized layer depth and surface carbon concentration were further specified. The results show that under carburizing temperatures of 930， 950 and 980℃， the measured values from the hardness gradient curve and carbon concentration gradient curve of the carburized layer are in good agreement with the expected ones. In additional， the carbon diffusion coefficient and austenite saturation carbon concentration increases with the carburizing temperature， and the carburizing efficiency is increased by 14%~17% when the temperature is increased by every 10℃.

References | Related Articles | Metrics

Numerical Simulation of Solidification Process During Vertical Continuous Casting

WANG Zhuo， LI Bao-kuan， LIU Zhong-qiu， NIU Ran

2020, 41 (9): 1257-1261. DOI: 10.12068/j.issn.1005-3026.2020.09.007

Abstract ( 870 )

HTML

PDF (875KB) ( 954 )

Solidification process in a vertical continuous casting was numerically simulated using a three-phase (mixed liquid-columnar-equiaxed grain) solidification model based on Eulerian-Eulerian approach and metal/alloy solidification theory. Comparing with the single-phase solidification model， more detailed phenomenons in addition to the thermo-solute natural convection are predicted， such as the evolutions of columnar and equiaxed grains， floatation/sedimentation of equiaxed grains can be predicted， which greatly affects the macroscopic solute transport and development of as-cast structure. The simulation results show that negative segregation occurs in the center of the billet， which filled with deposited equiaxed grains and next to this center， a ribbon segregation regions are observed. With the increasing superheat of molten steel， the region of equiaxed grain decreases and the macrosegregation at the center increases.

References | Related Articles | Metrics

Prediction and Optimization of Blast Furnace Parameters Based on Machine Learning and Genetic Algorithm

LI Zhuang-nian， CHU Man-sheng， LIU Zheng-gen， LI Bao-feng

2020, 41 (9): 1262-1267. DOI: 10.12068/j.issn.1005-3026.2020.09.008

Abstract ( 1142 )

HTML

PDF (657KB) ( 1435 )

To address the problem of low accuracy in the blast furnace ironmaking model， a precise multi-objective optimization model for the blast furnace production process was established.Firstly， the massive data from blast furnace were pre-processed before machine learning. Then， six kind of machine learning algorithms were used to predict coke ratio and K value， including support vector machine， random forest， gradient boosting regression tree， XGBoost， LightGBM and artificial neural network.Feature engineering and hyper-parameter tuning were used to optimize the prediction results from machine learning.Finally， the new ensemble learning method was used for prediction.Consequently， the proposed machine learning method has not only high accuracy， but also good robustness.Based on the prediction from machine learning， multi-objective optimization analysis of blast furnace parameters is further carried out by NSGA-Ⅱ algorithm so that Pareto optimal solution can be obtained. Therefore， the blast furnace operator can select the corresponding control parameters， according to these multi-objective optimization results.

References | Related Articles | Metrics

Instability Probability Analysis of Ring Stiffened Pressure Cylindrical Shell Structures Based on GPC

ZHANG Yi-bo， SUN Zhi-li， ZHAO Zhong-qiang， ZHAO Jing-wu

2020, 41 (9): 1268-1273. DOI: 10.12068/j.issn.1005-3026.2020.09.009

Abstract ( 672 )

HTML

PDF (930KB) ( 606 )

To evaluate the instability probability of deep submergence ring stiffened pressure cylindrical shell structures with small failure probability， an innovative adaptive analysis method based on Gaussian process classification (GPC) and importance sampling (IS) was proposed. By introducing the Markov Chain Monte Carlo (MCMC) and the Euclidean distance， a new adaptive strategy for design of experiments (DoE)， considering the prediction uncertainty and the sampling uniformity， was developed to establish the Gaussian process classifier more efficiently. Furthermore， the quasi-optimal importance sampling density function was constructed by adopting the kernel density estimation (KDE). Based on the stability of failure probability estimation， a more accurate stopping criterion was also proposed. A piecewise function was utilized to verify the accuracy and efficiency of the proposed analysis method. The instability probability of a deep submergence ring stiffened pressure cylindrical shell structure obtained by the proposed method is about 8.242×10^-5.

References | Related Articles | Metrics

A Compound Gradient Acceleration Optimization Algorithm with Adaptive Step Size

YIN Ming-ang， WANG Yu-shuo， SUN Zhi-li， YU Yun-fei

2020, 41 (9): 1274-1279. DOI: 10.12068/j.issn.1005-3026.2020.09.010

Abstract ( 848 )

HTML

PDF (733KB) ( 877 )

In related researches， a class of adaptive iteration step size accelerated(Adam) algorithms becomes a research hotspot because of its high computational efficiency and compatibility. To solve the problem of Adam′s low convergence rate， based on the combination of current gradient， prediction gradient and historical momentum gradient， this paper proposed a new kind of Adam algorithm named as compound gradient descent method(C-Adam)， and proved its convergence. The difference between C-Adam and other acceleration algorithms is that C-Adam distinguishes the prediction gradient from the historical momentum， and finds a more accurate search direction for the next iteration through a real gradient update. Using two testing data sets and the data of 45 steel static tensile experiment to test the C-Adam， the results show that the algorithm has faster convergence speed and smaller training loss compared with other popular algorithms.

References | Related Articles | Metrics

Dynamic Modeling and DME Evaluation of Power Transmission Line Inspection Robots

LI Xiao-peng， SHANG Dong-yang， LI Fan-jie， CAO Wei-long

2020, 41 (9): 1280-1284. DOI: 10.12068/j.issn.1005-3026.2020.09.011

Abstract ( 745 )

HTML

PDF (1973KB) ( 690 )

Taking the newly designed power transmission line inspection robot as the specific research object， the Jacobian matrix of the robot was derived using the D-H method and then the Lagrange dynamic model of the power transmission line inspection robot was established. The inertial matrix of the operating arm of the robot was obtained with the dynamic model， and the evaluation indexes of robot dynamics were put forward based on the inertial matrix of the operating arm— dynamic operability ellipsoid (DME) evaluation index. Finally， combined with the inverse solution of inverse kinematics， dynamic maneuverability indexes under different spatial trajectory coordinates were established， and the obstacle trajectory with the best robot dynamic performance was obtained. Experiments of robots crossing insulator barriers proved the effectiveness of the proposed dynamic evaluation method.

References | Related Articles | Metrics

Shortest Tool Path Generation Method for STEP-NC Complex Pockets Based on Graph Theory and Improved Dijkstra Algorithm

ZHANG Yu， LI Dong-sheng， WANG Zhi-wei， GONG Ya-dong

2020, 41 (9): 1285-1291. DOI: 10.12068/j.issn.1005-3026.2020.09.012

Abstract ( 616 )

HTML

PDF (1523KB) ( 767 )

Given little research on the tool path generation method for STEP-NC (standard for the exchange of product data- compliant numerical control， STEP-NC) complex pockets， a method was proposed to generate the shortest tool path of STEP-NC complex pockets based on the graph theory and improved Dijkstra algorithm. In the method， the closed equidistant ring of STEP-NC complex pockets was firstly generated according to cutting spacing and basic element offset. Then， the weighted digraph of the closed equidistant ring was obtained based on the graph theory. Finally， the shortest tool path of STEP-NC complex pockets was generated by the improved Dijkstra algorithm. The feasibility and effectiveness of the proposed method were verified by a case.

References | Related Articles | Metrics

Study on Mechanism and Theoretical Model of Tool Wear in Engineering Ceramics Turning

MA Lian-jie， WANG Xin， CHEN Jing-qiang， ZHOU Yun-guang

2020, 41 (9): 1291-1296. DOI: 10.12068/j.issn.1005-3026.2020.09.013

Abstract ( 792 )

HTML

PDF (821KB) ( 770 )

Based on the tribological principle and furrow effect， the effect of ceramic material on the wear mechanism of cutting tools was discussed by cutting experiment of lithium disilicate glass ceramics. By introducing the related parameters of ceramic crystal， the influence of the morphology and arrangement for ceramic crystal on the tool wear in the turning process was revealed， which made the application of wear mechanism more extensive and intuitive. Based on geometric and kinematic analysis， a model of the tool wear of turning tools for engineering ceramics was established and tested. Both the theoretical and experimental results show that， with the increase of cutting length， the wear volume first shows a steady increase， and then due to the increasing wear surface and the heat accumulation causes the phenomenon of bond wear， the tool wear speed increases sharply， and finally leads to the tool edge breakage and failure.

References | Related Articles | Metrics

Research on the Trajectory Tracking Control Method of Intelligent Vehicles

TANG Chuan-yin， ZHAO Yi-feng， ZHAO Ya-feng， ZHOU Shu-wen

2020, 41 (9): 1297-1303. DOI: 10.12068/j.issn.1005-3026.2020.09.014

Abstract ( 1366 )

HTML

PDF (1343KB) ( 1487 )

Aiming at the trajectory tracking control problem of intelligent vehicles， the trajectory tracking control method with adjustable parameters of intelligent vehicles was presented. Firstly， the fuzzy controller was designed to track intelligent vehicles. Secondly， in order to improve the path tracking effect of vehicles at high speeds， the model prediction controller was further designed， and the tire side deviation angle and centroid side deviation angle were restrained by combining the dynamic characteristics of tires and vehicles. Then， in order to improve the path tracking effect of vehicles under different working conditions， a model prediction controller based on PSO algorithm was further designed. The control effects with different methods were compared. Finally， the typical working conditions were selected for simulation on the joint simulation platform. The results showed that the proposed trajectory tracking control method of intelligent vehicles can effectively track the vehicle trajectory.

References | Related Articles | Metrics

Experiment of Magnetic Abrasive Finishing on TC4 Titanium Alloy Hole

JIAO An-yuan， ZHANG Guo-fu， DING Hao-dong， LIU Wei-jun

2020, 41 (9): 1304-1310. DOI: 10.12068/j.issn.1005-3026.2020.09.015

Abstract ( 756 )

HTML

PDF (3448KB) ( 519 )

The effects of process parameters on the efficient removal of burrs and cuts of TC4 titanium alloy hole， reduction of surface roughness R_a， and improvement of micromorphology were studied by using the built-in magnet to attract magnetic abrasive particles. Firstly， the orthogonal experiment of coaxial grinding of the magnetic pole and hole was carried out. According to the analysis of the range and variance， the effect of the magnetic pole speed， the abrasive diameter and the filling amount of abrasive on the surface roughness R_a and micromorphology were obtained， and a better combination of process parameters was determined. Secondly， the eccentric grinding test of magnetic poles and holes was carried out， and three-dimensional force testing was performed on the eccentric grinding and the test data was analyzed. The results show that:for 10mm holes of TC4 titanium alloy， a radial magnetic pole of 6mm is used， the surface burrs and cuts are removed， and the surface topography is uniform and flat after 30minutes grinding with an eccentricity of 1mm. Compared with the coaxial grinding， the surface roughness R_a is reduced by 13.7% and the grinding efficiency is increased by 25.0%.

References | Related Articles | Metrics

Output Feedback Adaptive Command Filtered Control of Electrohydraulic Actuator

YE Ning， SONG Jin-chun， GAO Xi-ying， YU Zhong-liang

2020, 41 (9): 1310-1315. DOI: 10.12068/j.issn.1005-3026.2020.09.016

Abstract ( 748 )

HTML

PDF (1086KB) ( 726 )

This paper proposed an output feedback adaptive robust command filtered control (CFC) scheme for tracking control of electrohydraulic actuator subjected to both structured and unstructured uncertainties. The proposed output feedback controller is developed by combining a modified LuGre friction compensation method and an adaptive robust CFC method. The adaptive law is raised to deal with the structured uncertainties. The robust design of the proposed controller is used to deal with unstructured uncertainty. Except for the available position signals， speed， pressure， and friction status are all received by observation. Modeling errors from observation are compensated with a robust design. CFC technology is utilized to deal with the inherently complex explosion problem of the classic backstepping technology. The proposed controller can guarantee asymptotic stability. Comparative experiments were carried out to verify the tracking performance of the proposed approach.

References | Related Articles | Metrics

Propagation Law of Dust Explosion in Complex Bend Pipes

LI Gang， HU Peng， ZHANG Yang-yang， NI Lei

2020, 41 (9): 1316-1320. DOI: 10.12068/j.issn.1005-3026.2020.09.017

Abstract ( 901 )

HTML

PDF (1181KB) ( 764 )

In order to understand the propagation law of dust explosions in bend ducts， variety of bend pipes were set up based on 1m³ explosion test system， including pipes with a 90-degree bend， S-shaped pipes， U-shaped pipes and long straight pipes. Corn starch was used as the explosion test sample. The overpressure development and flame propagation along the bend pipes were recorded by the computer and analyzed. For the established test rig， the results show that the explosion overpressure in the pipes shows a downward trend for the same dust concentration， but its attenuation rate at the bend part decreases. The attenuation rate of those four kinds of pipes is as follows:straight pipe>90-degree bend>S-bend>U-bend. Although the flame propagation velocity is continuously accelerated in the pipes， the bend hinders the flame propagation. The rate of flame propagation velocity rise in bend pipes is smaller than that in the straight pipes. The above research conclusions have reference and application value for the explosion proof design of the dust removal system.

References | Related Articles | Metrics

Effect of CO₂/N₂ Dilution on the Propagation of Laminar Flames of H₂/CH₄

SHANG Rong-xue， GAO Jun-hao， YANG Yue， LI Gang

2020, 41 (9): 1321-1327. DOI: 10.12068/j.issn.1005-3026.2020.09.018

Abstract ( 669 )

HTML

PDF (864KB) ( 777 )

The transmission speeds of laminar flames of H₂/CH₄/air mixtures with CO₂/N₂ dilution were experimentally studied using the Bunsen burner method incorporating the schlieren technique. To thoroughly investigate the diluted effect of CO₂/N₂ on laminar premixed flames of H₂/CH₄/air mixtures， the adiabatic flame temperatures， sensitivities of the mixtures with various CO₂/N₂ dilution ratios and the mole fractions of vital radicals were calculated using GRI-3.0 mechanism. The research results showed that GRI-3.0 mechanism provided better estimates of the transmission speeds of hythane flames; laminar flame speeds and adiabatic flame temperatures decreased with the growth of CO₂/N₂ dilution ratios. Compared with N₂， CO₂ presented the stronger thermal effect and chemical kinetics effect on the decrease of the laminar flame speeds of diluted hythane. With the increase of CO₂ dilution ratios， the dominant promotion of the oxidation reaction H+O₂O+OH on the mass burning rates of mixtures can be inhibited by the significant reductions of H radicals. Therefore， the laminar flame speed of mixtures remarkable decreased with the growth of CO₂ rations.

References | Related Articles | Metrics

Application of Simulated Annealing Clustering Algorithm in Grouping of Discontinuity Orientation

WANG Shu-hong， ZHU Bao-qiang， WANG Peng-yu

2020, 41 (9): 1328-1333. DOI: 10.12068/j.issn.1005-3026.2020.09.019

Abstract ( 682 )

HTML

PDF (994KB) ( 609 )

Aiming at the complexity， poor clustering accuracy and low grouping efficiency of the previous methods of dominant grouping of discontinuity orientation， a new method of dominant grouping of discontinuity orientation based on simulated annealing algorithm and K-means clustering (SAK) was proposed. The algorithm is simple and easy to implement. Based on the annealing principle of simulated annealing algorithm， the grouping results of K-means algorithm were optimized， which aimed to overcome the shortcoming of the K-means algorithm’s susceptibility to the initial clustering center. The analysis of discontinuities generated by computer simulation showed that the proposed method is superior to the traditional K-means algorithm. The method was applied to the grouping of measured discontinuity orientation of Xinglong Tunnel on Third Ring Expressway of Chongqing City， and compared with the existing methods. The results showed that this method not only has high clustering accuracy， but also has fast iteration speed and strong engineering practicability.

References | Related Articles | Metrics

Sealing Capacity Analysis of Cement Sheath Based on Combined Mechanical Model

WANG Hai-zhu， SHI Lu-jie， ZHENG Yong， ZHANG Cheng-cheng

2020, 41 (9): 1334-1340. DOI: 10.12068/j.issn.1005-3026.2020.09.020

Abstract ( 729 )

HTML

PDF (1004KB) ( 643 )

In order to explore the mechanism of cement sheath sealing failure during hydraulic fracturing， a failure analysis method of cement sheath sealing capacity based on combined casing-cement-formation elastic-plastic mechanical model was established. The reliability of the mechanical model and analysis method was verified by numerical simulation and experimental data. With the comparison of equivalent stress and yield strength， strain and ultimate elongation of the material， the cement sheath sealing capacity chart was drawn. The research shows that there is an optimal range for the influence of the elastic modulus of the cement sheath on its sealing capacity. Under the conditions presented in this paper， the elastic modulus of the cement sheath between 6 and 9.7GPa is beneficial to maintain its sealing capacity. This study can provide a reference for the cement parameters selection in horizontal well in different shale formations.

References | Related Articles | Metrics

Study on Frost Heave Resistance of Different Section Structures of U-Shaped Canal

WANG Yu-bao， WANG Liang， CHENG Sen-hao， HU Zhan-feng

2020, 41 (9): 1341-1347. DOI: 10.12068/j.issn.1005-3026.2020.09.021

Abstract ( 758 )

HTML

PDF (2007KB) ( 868 )

Aiming at the insufficient quantitative relationship between the obliquity and frost heave performance of canal lining， the mechanical model and numerical simulation were combined to study suitable U-shaped canal cross-section structure for local frost heave environment under different conditions， taking the D80 U-shaped canal as an example in Hetao irrigation district， Inner Mongolia. The results show that the smaller the obliquity and the narrower and deeper the canal， the greater the horizontal frost heave at the top of canal and the lager the stress at the bottom of canal. Conversely， the larger the obliquity and the wider and shallower the canal， the greater the vertical frost heave at the bottom of canal. The frost heave property of foundation soil and strength and thickness of concrete lining have a great effect on the frost heave resistance of canal. For loam soil， it is appropriate to choose 0.07m thick lining， 10° obliquity， and for silt soil， choose 0.08m thick lining， 13° obliquity.

References | Related Articles | Metrics

Experimental Study on Seismic Performance of Bottom-Flange-Bolted and Top-Flange-Welded Prefabricated CFST Column to Steel Beam Joints

RONG Xian， CHEN Lei， ZHANG Jian-xin

2020, 41 (9): 1348-1355. DOI: 10.12068/j.issn.1005-3026.2020.09.022

Abstract ( 729 )

HTML

PDF (1637KB) ( 752 )

In order to solve the problem of the influence of the joint on the overall seismic performance of the prefabricated concrete-filled steel tube (CFST) structure， this paper proposed a new type of the bottom-flange-bolted and top-flange-welded prefabricated CFST column and steel beam joints. To study its seismic performance， three bottom-flange-bolted and top-flange-welded joints and one full bolt joint were designed and tested. The results show that the failure modes of the three bottom-flange-bolted and top-flange-welded joints are mainly caused by the buckling of the beam end and the ductile fracture of the steel beam flange， the hysteretic curve of the joint is full， the energy dissipation capacity， stiffness degradation capacity and bearing capacity degradation capacity are good， and showing the seismic performance is close to that of the full bolt joint. Compared with JD1， the peak load， stiffness and energy dissipation capacity of JD3 are significantly improved with the increase of the beam section size， and the seismic performance of the joint is not significantly changed with an increase in the thickness of the plate.

References | Related Articles | Metrics

Risk Assessment of Social Networking Recruitment Based on Bayesian Network

WANG Xin， WANG Jing， LI Jin-feng

2020, 41 (9): 1356-1362. DOI: 10.12068/j.issn.1005-3026.2020.09.023

Abstract ( 672 )

HTML

PDF (529KB) ( 720 )

With the diversified development of social networking platforms， social networking recruitment has become a hot spot for enterprises. In order to effectively reduce the risks of corporate social networking recruitment， the flow chart method was used by combining the empirical research results and experts’ opinions to comprehensively analyze the risk factors of social networking recruitment. Then， on this basis， a risk evaluation index system of enterprises’ social networking recruitment was put forward， and the social networking recruitment risk evaluation model based on Bayesian network was established. Finally， the model was used for the risk assessment of an actual example of corporate social networking recruitment. The probabilities of the risks in each social networking recruitment stage and the overall probability of the risks in social networking recruitment were calculated and ranked， and then some suggestions were put forward， which verified the effectiveness of the evaluation method.

References | Related Articles | Metrics

Cell-Based Smoothed Finite Element Method for Elastic-Electro-Moisture Multi-physical Coupling Field

LI Ming， LIU Ming-rui， ZHOU Li-ming

2020, 41 (9): 1363-1368. DOI: 10.12068/j.issn.1005-3026.2020.09.24

Abstract ( 707 )

HTML

PDF (1148KB) ( 492 )

In order to solve the problem that piezoelectric-based structures were influenced by the moisture in air among the practical engineering application， the Cell-based smoothed finite element method was proposed for the elastic-electro-moisture multi-physical coupling field based on the constitutive equations， geometric equations and equilibrium equations of piezoelectric material. This paper established a piezoelectric-based energy harvester， and further investigated the static behavior of the simplified model. Furthermore， the effects of different moisture changes on the structure performance were studied. Comparing with the numerical results of finite element method， the Cell-based smoothed finite element method employing fewer elements can achieve the same accuracy as finite element method， which verified the accuracy and effectiveness of the as-proposed Cell-based smoothed finite element method. The numerical results show that a slight moisture change provides a strong effect on the generalized displacements of the structures. The investigation of piezoelectric structures under the humid environment provides the theoretical support for composite material productization process.

References | Related Articles | Metrics

Archive