Journal of Northeastern University(Natural Science)

Observer-Based Asynchronous Passive Control for T-S Fuzzy Generalized Switched Systems with Time Delay

YANG Dong-mei， WANG Ao

2021, 42 (11): 1521-1526. DOI: 10.12068/j.issn.1005-3026.2021.11.001

Abstract ( 758 )

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The concept of passivity is extended to T-S fuzzy generalized switched systems， and then the passivity problem for asynchronous situation between a class of subsystem switching and observer-based controller switching is studied. Firstly， by using piecewise Lyapunov function and model dependent average dwell time， the sub-systems with excess passivity can compensate for the sub-system with insufficient passivity， so as to ensure the overall passivity of the switched system. Afterwards， the sufficient conditions for globally uniformly exponential stability and strictly exponential passivity of T-S fuzzy generalized switched systems with time delay are obtained by using the linear matrix inequality method， and the corresponding observers and controllers are designed. Finally， numerical examples are provided to validate the effectiveness of the method.

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Fractional Differential Whittaker Smoother

SHAN Peng， HE Nian， LI Zhi-gang， WU Zhui

2021, 42 (11): 1527-1532. DOI: 10.12068/j.issn.1005-3026.2021.11.002

Abstract ( 755 )

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At present， the Whittaker Smoother(WS)algorithm is widely used. The core of the algorithm lies in the use of integer-order differentiation to express roughness. However， the integer-order differential representation is single and not flexible enough to truly reflect the roughness of the signal. On the contrary， the fractional differential expression is flexible and can better describe the roughness of the real signal. Therefore， the fractional differentiation is used to improve the WS algorithm and make it more flexible and effective. As two fractional differential calculation methods， Riemann-Liouville(RL)and Grümwald-Letnikov(GL)are adopted to implement the fractional WS algorithm.Furthermore， the automatic parameter selection of the fractional WS algorithm is realized by mathematical derivation. The experimental results of the nuclear magnetic resonance spectrum with sharp peaks show that the fractional-order WS algorithm can extract more real information; additionally， the experimental results of Marzipan infrared spectra show that the precision of spectral quantitative analysis is higher compared with the original integer-order WS algorithm.

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Link Prediction Algorithm Based on Improved TADW

CHEN Dong-ming， SUN Zheng-ping， YU Kai-shuai， WANG Dong-qi

2021, 42 (11): 1533-1539. DOI: 10.12068/j.issn.1005-3026.2021.11.003

Abstract ( 613 )

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Aiming at the problem that the classic node similarity link prediction algorithm only considers the network topology or node attribute information， the word embedding model Word2vec to learn the representation of node text attribute information is employed， and then TADW(text-associated deep walk)algorithm for its insufficient ability to express semantic information is improved. Based on the improved TADW graph embedding method， a similarity index which incorporate the topological structure and node attribute information is proposed. Furthermore， the link prediction algorithm is proposed based on this similarity index. Experimental results on three real datasets demonstrate the superiority of the proposed algorithm with better robustness on predicting precision as well as network sparsity solvability.

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A Real-Time Video Image Background Replacement Method Based on Deep Learning

XIE Tian-zhi， LEI Wei-min， ZHANG Wei， LI Zhi-yuan

2021, 42 (11): 1540-1546. DOI: 10.12068/j.issn.1005-3026.2021.11.004

Abstract ( 1039 )

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Aiming at the real-time requirement of video session service， a lightweight deep learning network model is proposed to realize the real-time background replacement function of video images. The network model includes two modules: semantic segmentation and background replacement. The whole architecture of semantic segmentation module adopts encode-decoder structure. Encoder module， dilated convolution pyramid pooling module， attention module， and gain module are used in the encoding terminal to extract features. Decoder module， adjustment module， and encoder module are used in the decoding terminal to recover the image， and the background replacement module is used to complete the background replacement. After the data-set training， the segmentation accuracy of the network model reaches 94.1%， and the segmentation speed reaches 42.5 frames/s， which achieves a good balance between real-time and accuracy， and has a good practical effect.

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Atrial Fibrillation Detection Method Based on Phase Space Reconstruction Using Ballistocardiogram Signal

JIANG Fang-fang， WANG Hao-qian， CHENG Tian-qing， HONG Chu-hang

2021, 42 (11): 1547-1554. DOI: 10.12068/j.issn.1005-3026.2021.11.005

Abstract ( 635 )

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Based on the arrhythmia characteristics of atrial fibrillation(AF)， phase space reconstruction(PSR)is applied to extract the 2D rhythmic feature of the ballistocardiogram(BCG)signal. In the process of reconstruction， the optimal embedding dimensions and time delay parameters are discussed. Firstly， the heart beat is regarded as a non-linear dynamic system， and the 1D time series is mapped to the high-dimensional phase space， based on the phase space reconstruction theory， to obtain the 2D trajectory， which describes the abnormal rhythm of AF in BCG signal. Secondly， the optimal embedding dimension and time delay parameters of the reconstruction procedure for AF diagnosis are discussed， and the convolutional neural network(CNN) is applied to identify AF automatically. Finally， 2000 BCG segments from 59 subjects are used to validate the classification performance. The accuracy reaches 91.00% by means of the tenfold cross-validation. Compared to the machine learning method based on the classical time-frequency features， the accuracy is improved， which verifies the superiority of the proposed method.

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Preparation and Interface Characterization of Fe-Al Micro-laminated Composites

ZU Guo-yin， ZHANG Ying， WEI Zhen-xiong， MAN Ting

2021, 42 (11): 1554-1561. DOI: 10.12068/j.issn.1005-3026.2021.11.006

Abstract ( 687 )

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Layers of pure iron and pure aluminum sheets were alternately stacked， and the Fe-Al metal-intermetallic-laminate(MIL)composites were prepared by the process of hot-rolling compound， cold-rolling reduction and alloying treatment. The effects of alloying temperature on the microstructure， phase composition， phase transformation， and mechanical properties of the Fe-Al MIL composite were investigated. The results show that the prepared Fe-Al MIL composite has a good Fe/Al interface bonding state. As the alloying temperature increases， the thickness of the compound layer increases. When the temperature is lower than the Fe-Al solid/semi-solid reaction temperature of 655℃， Fe₂Al₅ and FeAl are the main phases in the compound layers. When the temperature is above 655℃， a small amount of FeAl₃ and Fe₃Al appear alternately at the interface between the compound layer and the Fe matrix.The DSC curve shows there are three exothermic peaks of ~559， ~571 and ~667℃， which represent the phase transitions of FeAl₃， Fe₂Al₅， and FeAl， respectively. The mechanical properties of the Fe-Al MIL composites obtained after solid-solid and solid-liquid alloying are poor， and both are prone to delamination fracture. The best performance of Fe-Al MIL composite can be achieved after the solid/semi-solid alloying treatment.

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Effect of Substrate Temperature on Corrosion Resistance of NdFeB-Based TiN Protective Film

XIE Yuan-hua， DENG Wen-yu， WANG Peng-yang， WAN Yi

2021, 42 (11): 1562-1568. DOI: 10.12068/j.issn.1005-3026.2021.11.007

Abstract ( 495 )

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In the process of NdFeB rare-earth permanent magnet corrosion protection， the substrate temperature of TiN protective membrane takes a great influence on protective effect. The magnetron sputtering technology was carried out to deposit TiN film on NdFeB permanent magnet surface and the effects of substrate temperature on the microstructure and corrosion protection performance of TiN film were studied through FESEM， XRD， electrochemical detection and permanent magnetic nondestructive testing technologies. The results showed that the substrate temperature had a great influence on the film’s property. The increase of temperature was conducive to the growth of grain and to promote the TiN (111) texture. It was found that the corrosion resistance of the film was the strongest at the substrate temperature of 300℃ with the greatest loss of magnetic property. When the substrate temperature was 100℃， the film had the best protective performance on the substrate， associated with a stronger corrosion resistance and less loss of magnetic property.

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Thermal Error Modeling of Numerical Control Machine Tools Based on Neural Network Neural Network by Optimized SSO Algorithm

HUANG Zhi， LIU Yong-chao， LIAO Rong-jie， CAO Xu-jun

2021, 42 (11): 1569-1578. DOI: 10.12068/j.issn.1005-3026.2021.11.008

Abstract ( 724 )

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In order to explore the complex thermal characteristics of five-axis NC(numerical control) machine tools， a method for thermal error modeling of cradle five-axis NC machine tools was proposed. The principle of shark smell optimization(SSO)algorithm and neural network composite modeling was adopted， which effectively improved the accuracy and modeling efficiency of the machine tool thermal error prediction model. Firstly， the temperature sensitive point was screened by using the thermal imager， and then the temperature sensor was placed at the position of the heat sensitive point of the machine tool. The collected thermal characteristic data were modeled by the above method. The results showed that the method is better than ABC neural network and PSO neural network in terms of modeling speed and accuracy. Finally， the model was applied to the thermal error compensation experiment of the five-axis machine tool， which improves its accuracy by 32%.

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Impact Mechanism of Icon Layout on Visual Search Performance

JIN Tao， MING Cheng-ye， ZHOU Shu-fang， HE Jia-min

2021, 42 (11): 1579-1584. DOI: 10.12068/j.issn.1005-3026.2021.11.009

Abstract ( 608 )

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The classic search paradigm was used to study the impact of icon visual features and number changes on the cognitive performance of icon layout. Experiments showed when the number of icons was 6， only the main effect of icon visual features was significant， the icon layout had no significant effect on the search speed， and the icon visual features were the main influencing factor of cognitive performance; when the number of icons was 15， only the main effect of icon layout was significant， and the search speed of horizontal arrangement was the fastest. When the number of icons was more than 10， the reaction time of horizontal arrangement was significantly lower than that of vertical arrangement， and there was no significant difference in the error rate between them; with the decrease of L_{○ 长度}/S_宽度 ratio of graphic panel， the average reaction time difference between the two was gradually reduced and tended to be the same. Research showed that the number of icons has a significant impact on the cognitive performance of icon layout and visual features.

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Assessment of Suitability of Land Space Development Based on Parallel Spatial Overlay Analysis

YANG Yi-zhou， WU Li-xin， GUO Jia-teng， LIU Shan-jun

2021, 42 (11): 1585-1590. DOI: 10.12068/j.issn.1005-3026.2021.11.010

Abstract ( 502 )

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In the environment of land space big data， the performance of spatial development suitability evaluation based on serial superposition analysis has reached the extreme. In order to use more computing resources to improve the efficiency of spatial development suitability evaluation， it is necessary to study the parallelization method. Based on overlay analysis for multi factor of the principle of comprehensive evaluation， the spatial data preprocessing method， spatial data partition method and parallel spatial index are introduced， and the spatial development suitability evaluation based on parallel overlay analysis is realized. The application of this method in the suitability evaluation of space construction land in four provinces in Southwest China breaks the situation of low efficiency or incompetence in large-scale calculation under the traditional framework， and the efficiency has increased more than 30 times.

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Experimental Investigation of Mechanical Properties of Three Types of High Temperature Rocks After Liquid Nitrogen Cooling

DONG Shuo， SHA Song， MENG Shi-qian， RONG Guan

2021, 42 (11): 1591-1599. DOI: 10.12068/j.issn.1005-3026.2021.11.011

Abstract ( 603 )

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In order to investigate the effect of liquid nitrogen on the physical and mechanical properties of high-temperature rocks， a series of laboratory tests were carried out on granite， gneiss and sandstone specimens cooled with liquid nitrogen at different temperatures(25~350℃). The damage mechanisms of the three types of rocks were analyzed in combination with microscopic observations.The results show that the increase in temperature exacerbates the damage to the internal structure of the rock induced by liquid nitrogen. With the increase of temperature， the porosity and peak strain of the rock gradually increase， while the P-wave velocity， compressive strength and elastic modulus of the rock decrease. Thermal stresses generated by heating and liquid nitrogen cooling lead to the initiation and propagation of microcracks mainly along quartz mineral boundaries within the rock. The sensitivity of the three types of rocks to heating and liquid nitrogen cooling differs， depending on the lithogenesis， mineral composition， type of cementation， and pore structure of rocks.

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Study on Mechanical Properties of Sandstone Based on Voronoi Block Model

SUN Hao ， CHEN Shuai-jun ， JIN Ai-bing ， LI Hai

2021, 42 (11): 1600-1608. DOI: 10.12068/j.issn.1005-3026.2021.11.012

Abstract ( 566 )

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The spherical particle and parallel bond model(PBM)in PFC(particle flow code) software is widely used to simulate the mechanical properties of rock. However， spherical particles and PBM have two intrinsic drawbacks: the grain shape of spherical particles is quite different from that of rock materials， and the ratio of unconfined compressive strength to tensile strength(UCS/TS)is low. Based on this， taking the typical sandstone in Lüliang area of Shanxi Province as an example， the rigid block numerical specimens are established by Voronoi tessellations， and the mechanical properties of sandstone are studied by using the softe-bond model(SBM). The results show that the scheme has three advantages compared with the traditional numerical simulation based on spherical particles and PBM: compared with the spherical sample， the grain interlocking between the rigid blocks increases， and the coordination number between the rigid block models increases significantly， which can better simulate the grain shape and mechanical behavior of real sandstone. The SBM can simulate the larger unconfined compressive strength to tensile strength ratio of sandstone， which can truly characterize the mechanical properties of sandstone under multiple stress paths. The numerical model based on rigid block and SBM can truly reflect the typical shear failure mode of sandstone.

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A New Prediction Model for Peak Shear Strength of Rock Joints Considering the 3D Morphology Parameters

WANG Shu-hong， YIN Hong， ZHANG Ze， WEI Wei

2021, 42 (11): 1609-1617. DOI: 10.12068/j.issn.1005-3026.2021.11.013

Abstract ( 481 )

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The apparent dip angle and the distribution parameter are camprehensively analyzed to correct Grasselli’s 3D morphology parameters system as well as get a new prediction model reflecting the shear behavior of rock joints. The single-valued distribution function A^*_θ△* is used as the weight function to calculate the average apparent dip angle. By defining the relative distribution parameters C^*， revealing the control function of distribution parameters on resisting shear. A new peak shear strength prediction model is proposed. Compared with Grasselli’s model， the prediction accuracy of the new model is better verified through 50 sets of published data. The physical and mathematical boundary of distribution parameter C is proposed， and the phenomenon that the value of C from experiments is not less than 1 is explained. The distribution law of apparent dip angle and the composition of initial dilatancy angle are summarized， and the Grasselli’s model is classified into a unified form.The new prediction model has concise parameters， clear physical meaning and mathematical definition， and reveal the shear mechanism of rock joints.

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Analysis of Interface Stress of Grouting Rockbolt and Calculation of Critical Anchorage Length

ZHANG Yao-sheng， WANG Lian-guang， HUANG Xiao-bin， CHENG Bai-ling

2021, 42 (11): 1618-1624. DOI: 10.12068/j.issn.1005-3026.2021.11.014

Abstract ( 647 )

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To clarify the mechanism of the grouting rockbolt with a semi-infinite anchorage length， the interface mechanical property of the rockbolt was analyzed and the corresponding pull-out equations were present. Assuming that the shear stress distribution of the elastic part of the anchor rod along the anchoring depth was a quarter elliptical arc， and then the calculation formula of the critical anchorage length of the grouting rockbolt was given. To verify the correctness of the present method， in-situ pull-out tests were carried out on 4 anchor rods with anchoring lengths of 6.0m and 8.5m， respectively. The results showed that the axial strain distribution curve calculated by the present method was consistent with the experimental results， and the axial strain decreases nonlinearly with the anchoring depth. The critical anchorage length calculated by the present method was 5.3m， which was 3.6% different from the test result. The method presented in the manuscript was universal， and the calculation results obtained by the present method were relatively conservative compared with the results obtained by previous research.

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Image Classification of Corroded Steel Reinforcement Based on Optimized Residual Network

FANG Liang， ZHOU Yun， TANG Zhi-quan

2021, 42 (11): 1625-1633. DOI: 10.12068/j.issn.1005-3026.2021.11.015

Abstract ( 531 )

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A classification method for corroded steel reinforcements based on the residual network(ResNet) was proposed， and a new scheme and technical reference for further realizing accurate quantitative evaluation on corrosion ratio of steel reinforcement on-site was provided. A total of 1478 steel reinforcements with diameters of 12mm and 14mm and corrosion ratio of 1.45%~56.10% are taken as the experimental objects. The images of steel reinforcements are taken by industrial cameras under laboratory conditions， and the total of 23648 sample images are acquired by using the data enhancement techniques. Then， 11 kinds of sample image labels are determined according to the corrosion ratios. The ResNet structure is built based on the deep convolutional neural network， and the Adam algorithm is used for iterative optimization. The classification accuracy and training rounds are evaluated by comparing the experimental results of different data sets. To verify the applicability of the proposed method， 6 data sets are formed from sample images of different diameter of steel reinforcements for the training and testing. The experimental research shows that after 100 rounds of iterative training， the classification accuracy of corrosion degree of steel reinforcements for 6 kinds of data sets are more than 93.2%， and the highest is 98.8%. It also indicates that the proposed method supports the high-precision classification of corrosion reinforcement with mixed diameters， and has good practical applicability.

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Experiment and Simulation of Dust Explosion Propagation in Tapered Pipelines

LI Gang， ZHANG Xiao-yu， HUANG Ting-chuan， ZHANG Yang-yang

2021, 42 (11): 1634-1640. DOI: 10.12068/j.issn.1005-3026.2021.11.016

Abstract ( 632 )

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In order to investigate the propagation of dust explosion in the tapered pipelines， DN200-long straight pipeline and DN200~DN100 tapered pipeline were built based on 1m³ dust explosion chamber testing system. Using corn starch as the testing sample， the flame propagation speed， the peak overpressure in the pipeline and the flame propagation distance were studied by experiment and FLACS numerical simulation. It was found that the flame propagation velocity in the pipeline generally shows an increasing trend， especially after the diameter changing point of the pipe. The reduction of the pipe diameter accelerates the flame propagation. The peak overpressure in the pipeline shows a downward trend， and its attenuation amplitude increases significantly after reducing the diameter. The reduction of the pipe diameter makes the overpressure attenuation rate increased，the mathematical model of the overpressure change in the explosion cavity caused by the variable diameter pipeline is established by data fitting，the flame propagation distance becomes longer as the dust concentration in the chamber increases， and the flame propagation distance becomes longer as the pipe diameter is reduced largely.The research provides reference and guidance for the determination of the safety distance of the dust removal system and the design of fire and explosion prevention measures.

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Influence of “Government-Industry-University” Cooperation on Entrepreneurial Activity:Qualitative Comparative Analysis from the Perspective of Triple Helix

JIA Jian-feng， LIU Wei-peng， ZHANG Wei-guo

2021, 42 (11): 1640-1649. DOI: 10.12068/j.issn.1005-3026.2021.11.017

Abstract ( 512 )

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To explore the complex causal mechanism that affects the differences in entrepreneurial activity among regions， based on the triple helix theory， the configuration thinking and qualitative comparative analysis (QCA) method are used to integrate six conditional variables at three levels of government-industry-university. Results found that: any single element of government-industry-university does not constitute a necessary condition for high entrepreneurial activity in regions， and regions have not increased entrepreneurial activity in accordance with a certain fixed pattern. The driving mechanism of high entrepreneurial activity can be divided into three paths: “government-university” coordination-driven path， “government-industry” coordination-driven path and “industry-university” coordination-driven path. At present， no region uses the perfect synergy of “government-industry-university” to achieve high entrepreneurial activity， and it is limited to the coordinated operation of the two.

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Four-Block Layout Algorithm for Two-Dimensional Plate Shearring and Punching of Circular Parts

PAN Wei-ping， FAN Zhi-ping， HUANG Min

2021, 42 (11): 1650-1655. DOI: 10.12068/j.issn.1005-3026.2021.11.018

Abstract ( 626 )

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A cutting stock algorithm based on four-block layout was proposed to solve the two-dimensional plate shearring and punching of circular parts. With this layout， a sheet was divided into four blocks. Only the strips with the same direction and length were arranged in each block， and several rows of the same circular parts were arranged in the strips. A four block layout method for generating circular parts on a single sheet by constructing a layout algorithm. Firstly， the layout of circular parts in the strips was determined. Secondly， recursive algorithm was constructed to generate the layout of the strips in blocks. Finally， implicit enumeration algorithm was used to determine the optimal four-block partition. The column generation algorithm was used to call the above layout algorithm to generate a number of different layouts. Based on the simplex principle， a group of layouts were selected to form the cutting plan， and the decimal solution was rounded. The results showed that the plate utilization ratio of the algorithm in the study is 0.49%， 0.32%， 6.04% and 1.50% higher than those of the four literature algorithms， respectively， and the calculation time can meet the needs of practical applications.

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Growd Emergency Evacuation Model Based on Dynamic Emotion Drive

LI Jia-yang， TANG Jia-fu， GUO En-ming

2021, 42 (11): 1656-1662. DOI: 10.12068/j.issn.1005-3026.2021.11.019

Abstract ( 746 )

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Aiming at the crowd dynamic behavior in emergency evacuation， emotion perception and infection mechanism are combined into behavior decision-making. Based on the susceptible-infectious-susceptible model (SIS model)， emotion updating function is constructed in order to improve the dynamic field and transition probability of cellular automata. By analyzing the performance of the constructed model， it is verified that the emergency evacuation model conforms to the dynamic characteristics of crowd flow. Moreover， through simulation experiments， the effect of system parameters is analyzed on dynamic behavior switching， and the impacts of such parameters of dynamic behavior switching as emotional intensity threshold， infection coefficient， and calmness coefficient are explored. The results show that the individual emotional intensity threshold determines the individual final state of the system. The infection and calmness coefficients affect the rate of state change and evacuation time. This research provides a theoretical basis for the management of evacuated crowd.

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Optimization of Buses’ Flexible Departure Intervals Considering Crowdedness State

PEI Yu-long， YANG Shi-jun， PAN Heng-yan

2021, 42 (11): 1663-1672. DOI: 10.12068/j.issn.1005-3026.2021.11.020

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In order to improve the travel service quality of conventional bus， an optimization model of buses’ flexible departure intervals considering crowdedness state in the bus is established. By quantifying the crowdedness state in the bus， the travel cost under each crowdedness state is given， and the crowdedness state transfer function of each section of the line is established. Considering passengers’perception of the crowdedness state in the bus， the measurement model of the number of passengers getting on and off the bus over time is established; the travel cost measurement model is established， and the optimization model of buses’ flexible departure intervals is established with the objective function of minimizing the sum of passenger travel cost and vehicle operating loss; and the genetic algorithm is designed to solve the model. The results show that the optimization model can effectively reduce the travel cost. The model has a “short board filling” effect on the waiting cost， and a “peak cutting” effect on the travel cost. That is， by increasing the waiting cost of the stop with fewer passenger arrivals， reducing the waiting cost of the stop with more passenger arrivals and weakening the peak value of the travel cost， the total cost can be minimized.

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