Journal of Northeastern University(Natural Science)

A Dynamic Flame Image Segmentation Method and Its Application in Video Monitoring of Fused Magnesium Furnace Process

LU Shao-wen， LI Peng-qi， ZHENG Xiu-ping， GUO Zhang

2019, 40 (2): 153-158. DOI: 10.12068/j.issn.1005-3026.2019.02.001

Abstract ( 565 )

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The color， brightness distribution and shape pattern of flames vary under different working conditions， thus showing multi-modality. In addition， the background environment is highly coupled with the foreground image because of the reflection， aerosol， dust and other interferences. Traditional segmentation algorithms cannot ensure accuracy under a variety of conditions. A method of flame image segmentation based on multivariate image analysis and expert knowledge is proposed. The principal component analysis method was used to reduce the dimension of images and to construct the scatter plot of the scores， so as to obtain the regions of flame segmentation. The method was applied to the video monitoring of the production of fused magnesium furnace， which verified the performance of this method.

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Retinal Image Segmentation Based on Multifractal Detrended Fluctuation Analysis

ZHANG Shi， SHE Li-huang， WANG Ya-fan， SU Ting

2019, 40 (2): 158-163. DOI: 10.12068/j.issn.1005-3026.2019.02.002

Abstract ( 666 )

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A method based on multifractal detrended fluctuation analysis(DFA)， which is adaptable for unsteady images， is introduced to segment retina images. In this method， histogram equalization is first used to precondition images for the enhancement of blood vessels， and then， the generalized Hurst index of images is calculated by multifractal DFA. The blood vessel index is used to segment the blood vessels. Finally， morphological postprocessing is used to get the final blood vessel images. Experiments based on DIARETDE0 and DIARETDE1 databases show that the proposed method has better integrity and connectivity in the treatment of retinal lesions， and it can extract the main body of blood vessels better， which has a good clinical value.

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IT Outsourcing Schedule Risk Control Based on Two-Level Hybrid Genetic Algorithm

WANG Lei-zhen， ZHU Jin-wen， LU Fu-qiang ， WANG Ding-wei

2019, 40 (2): 164-169. DOI: 10.12068/j.issn.1005-3026.2019.02.003

Abstract ( 711 )

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Focusing on the optimization problem of schedule risk control in information technology(IT)outsourcing project， a two-level hybrid genetic algorithm(TLHGA)is proposed. The TLHGA incorporates simulated annealing， adaptive mechanism and the two-level feature of optimization problem to improve the traditional genetic algorithm(TGA)， which could overcome the shortcomings of TGA such as early mature and weak local searching ability. In the experimental analyses， the management meanings of the two-level mathematical model in IT outsourcing schedule risk control is analyzed. Next， the simulation results of TLHGA are compared with the TGA and two-level particle swarm optimization algorithm， which verifies the rationality and effectiveness of the improved algorithm.

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Application of Convolutional Neural Networks in Computer-Aided Diagnosis of MRI Images

WANG Yang， LIU Ji-ren， ZHAO Da-zhe， QIU Dao-yun

2019, 40 (2): 169-173. DOI: 10.12068/j.issn.1005-3026.2019.02.004

Abstract ( 848 )

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Based on convolutional neural networks， this paper proposes innovative ideas for diagnosing intracranial tissue and organ diseases. The images of Parkinson’s disease patients were preprocessed by gray mapping， histogram equalization， improved wavelet denoising and image enhancement. A convolutional neural network is designed and built on the basis of VGG-Net network model. Regularization strategy is adopted to avoid over-fitting problem. Then the ten-fold cross-validation of the network model is carried out five times with MRI image set of patients. And feature visualization is performed by deconvolution network to dig out latent features of diseases. The result and objective evaluation show that the network can make a good diagnosis of MRI image for Parkinson’s disease.

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Deep Neural Network Pruning Based Two-Stage Remote Sensing Image Object Detection

WANG Sheng-sheng， WANG Meng， WANG Guang-yao

2019, 40 (2): 174-179. DOI: 10.12068/j.issn.1005-3026.2019.02.005

Abstract ( 1028 )

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In the object detection of high-resolution remote-sensing images， affected by cloud， light， complex background， noise and other factors， the existing object detection method has high false alarm， low speed and low precision. So we propose a two-stage object detection method based on deep pruning. First， we propose deep pruning， and then based on the deep pruning we propose an algorithm that learns region proposal network automatically and an algorithm that we train classification network with optimizing training method. We then apply the two algorithms to convolutional neural network and get a two-stage object detection model. The experiment result shows that our method has a certain improvement on precision and speed compared with the state-of-the-art method.

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Mobile Communications Customer Churn Prediction Algorithm Based on Improved GA-BP Network

YU Rui-yun， XUE Lin， AN Xuan-miao， XIA Xing-you

2019, 40 (2): 180-185. DOI: 10.12068/j.issn.1005-3026.2019.02.006

Abstract ( 715 )

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A customer churn prediction model based on BP neural network(BPNN)has achieved well enough results. However， it has relatively weak global search ability and is very sensitive to the initial network weights. A prediction algorithm based on improved genetic algorithm(IGA)and BPNN(IGA-BP)is proposed by analyzing users’communication behavior， where the weights and thresholds of BPNN are initialized with IGA， thus improving the accuracy of the prediction model. The improved algorithm adopts a self-adapting probability of crossover and mutation， which enhances the global optimum search ability of GA. The proposed IGA-BP model has obvious improvement on customer churn prediction， compared with existing algorithms.

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Community Detection Algorithm for Complex Networks Based on Group Density

CHEN Dong-ming， WANG Yun-kai， HUANG Xin-yu， WANG Dong-qi

2019, 40 (2): 186-191. DOI: 10.12068/j.issn.1005-3026.2019.02.007

Abstract ( 692 )

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Most of the traditional community detection algorithms cannot balance partitioning effect and complexity well. So， this paper presents a new evaluation standard of single community called group density. Based on the group density， a community detection algorithm based on agglomeration is proposed. The algorithm continues to integrate small communities， and makes the community structure of the network develop in the direction of maximizing average group density. Modularity is employed to detect the partitioning effect of the algorithm. Experimental results demonstrate that the new algorithm outperforms the traditional GN， Fast Newman， LPA algorithms in multiple data sets， which shows that the algorithm proposed has better partitioning effect and lower time complexity.

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Effect of Semi-solid Deformation on Carbides in M2 High-Speed Steel

LIU Cheng-yu

2019, 40 (2): 192-197. DOI: 10.12068/j.issn.1005-3026.2019.02.008

Abstract ( 549 )

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Based on semi-solid forming technology， an advanced process was applied to the elimination of harmful carbide chunks in M2 high-speed tool steel. To verify the feasibility of the process， on the conditions of different deformation temperatures regarding to solid-liquid fraction and different deformation modes， the morphology and distribution of different types of carbides were studied by optical and electron microscopes， the distribution of different elements in carbides was characterized by EPMA， and the effects of the new process on solidification structure and harmful carbides were analyzed. The results show that the area fraction of the harmful carbides in the M2 high speed steel decreases when the sample deformes with the higher liquid fraction， which helps to improve the solidification structure of the alloy. Especially， when the process of two pass deformation at 1345 and 1100℃ of 25% and 30% respectively is used， the carbide volume fraction in the sample can be reduced to 6.5% from 14.3% as-cast.

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Numerical Simulation and Processing Investigation on Differential Thickness Rolling of Thick Steel Plate

WU Xiao-gang， HE Chun-yu， JIAO Zhi-jie， WANG Jun

2019, 40 (2): 197-201. DOI: 10.12068/j.issn.1005-3026.2019.02.009

Abstract ( 625 )

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Based on ABAQUS finite element software， dynamic coupling process about three-dimensional conventional rolling and differential thickness rolling for thick steel plates were simulated by an explicit dynamic algorithm. The flow feature and the stress/strain distribution in the distorted region were obtained， the variation laws of rolling force and rolling moment during the process of conventional rolling and differential thickness rolling were studied and the improvement of the biting condition of steel plate during rolling process was analyzed. The results of the differential thickness rolling process show that the reasonable process for the differential rolling can overcome the bite limit of slab rolling， reduce the influence of peak torque caused by head impact and increase the penetration of the core deformation thickness of thick steel plate. Moreover， it can also improve the deformation uniformity and microstructure uniformity at a certain degree.

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Properties of Glass Beads Prepared by Gas Quenching of Blast Furnace Slag

KANG Yue， LIU Chao， ZHANG Yu-zhu， JIANG Mao-fa

2019, 40 (2): 202-206. DOI: 10.12068/j.issn.1005-3026.2019.02.010

Abstract ( 845 )

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The bulk density， particle size distribution， chemical erosion， cylindrical compressive strength and morphology of air-quenched BFS(blast furnace slag)are measured by experiments.The results show that the bulk density increases first and then decreases with the increase of particle size and is the largest in the particle size range of 0.30~1.0mm.The size of slag beads is mainly between 0.30~1.0mm where the bead yield is high. The slag beads do not resist acid erosion. In terms of erosion resistance， larger slag beads are better than smaller ones in the same erosion solution.The smaller the particle size， the greater the cylinder compressive strength of the slag beads and the stronger the ability to bear pressure. The surface of slag beads is smooth and spherical， and the particle size is uniform.The content of amorphous phase of the slag beads is high because of the rapid cooling rate of the slag beads by gas quenching. When the slag beads sizes are less than 0.30mm， the XRD curve becomes the shape of a teamed bread， showing that crystal phase is hardly precipitated and the minerals are amorphous.

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Comparative Study on Metallurgical Performance of Different Vanadium-Titanium Magnetite Burdens

HE Zhan-wei， XUE Xiang-xin

2019, 40 (2): 207-211. DOI: 10.12068/j.issn.1005-3026.2019.02.011

Abstract ( 725 )

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The phase composition and microstructure of sinter and pellet of two typical vanadium-titanium magnetites were studied. The softening-smelting-dripping properties of burden(sinter+pellet)were measured through simulation in laboratory. The results show that high chromium vanadium-titanium magnetite sinter is mainly composed of magnetite， hematite and a small amount of calcium ferrite and silicate， while high titanium vanadium-titanium magnetite sinter contains more calcium ferrite， silicate and perovskite. However， there are no significant differences in phase composition and microstructure between the two pellets. Compared with high titanium vanadium-titanium magnetite burden， high chromium vanadium-titanium magnetite burden has higher melting temperature and narrower melting range， which are beneficial to blast furnace. The matrix phase of non-dripped slag of high chromium vanadium-titanium magnetite is melilite， but the non-dripped slag of high titanium vanadium-titanium magnetite contains pyroxene as matrix phase and TiC around metallic iron.

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CO₂ Emissions Characteristics and Source Analysis of “Chinese Style” Electric Arc Furnace Steelmaking Route

NA Hong-ming ， GAO Cheng-kang ， GUO Yu-hua， TIAN Fan

2019, 40 (2): 212-217. DOI: 10.12068/j.issn.1005-3026.2019.02.012

Abstract ( 1440 )

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Electric arc furnace steelmaking route does not play the role of carbon reduction in China due to the excessive use of hot metal. This unique route is called the “Chinese style” electric arc furnace steelmaking route. Employing the emission factor method， the Sankey diagram of CO₂ emissions of “Chinese style” electric arc furnace steelmaking route is built to explore the path of carbon emissions. The results show that the CO₂ emissions per ton of steel in the whole route are 3.070t， among which the CO₂ emissions from electric arc furnace steelmaking takes the largest share of 1.400t. Particularly， excessive CO₂ emissions of 1.419t are produced because of the utilization of hot metal for electric arc furnace steelmaking. The reason for the excessive use of hot metal is that China’s steel industry is in the developing period， the scrap steel index is low， the recovery and utilization system of scrap steel is incomplete and the price of industrial electricity is high.

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Physical Simulation of Atomization Effect of Rare-Earth Chloride Spray Pyrolysis Device

LIU Yan， LI Xiao-long， ZHANG Chen， ZHANG Zi-mu

2019, 40 (2): 218-223. DOI: 10.12068/j.issn.1005-3026.2019.02.013

Abstract ( 651 )

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Spray pyrolysis rare-earth chloride is a new process to produce rare-earth oxides， but there are some shortages at present such as the poor atomization effect of spray pyrolysis equipment and the non-uniform distribution of the droplet size after atomization. A Venturi tube spray pyrolysis reactor was designed and particle image velocimetry technology combined with MATLAB image processing technology was used to analyze the effects of gas flow rate， the size of Venturi tube and drainage tube on the atomization. The results show that the strong back-flow in the diffuser of Venturi tube can intensify the collision of gas-liquid phases and crush more drops， while the excessive amount of liquid phase in the Venturi tube increases the droplet density and collision probability of droplet in motion， leading to larger droplet size. The suitable geometric size for Venturi tube reactor are 100mm-inner diameter， 10mm-throat diameter， 5mm-inner diameter of drainage tube and the gas flow rate of 20.5m³/h.

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Influence of Concentration Difference on Electrolysis Process of Li₂CO₃ Direct Preparation

PAN Xi-juan， ZHANG Ting-an， DOU Zhi-he， HAN Xiu-xiu

2019, 40 (2): 224-228. DOI: 10.12068/j.issn.1005-3026.2019.02.014

Abstract ( 762 )

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The variations of cathode liquid pH and temperature and the phase composition and microstructure of Li₂CO₃ products were studied during the electrolytic process when the anolyte concentration was 300g/L and catholyte concentration were 50， 100， 200， 300 and 400g/L， respectively. The results show that the concentration or concentration difference has little effect on the reaction mechanism in the electrolysis process， while the concentration difference has a great influence on the speed and the limit of the reaction. The amount of Li₂CO₃ products and current efficiency increase with the decrease of the concentration difference or concentration of catholyte. The crystallography of Li₂CO₃ produced from electrolysis is monoclinic. Moreover， the concentration difference not only increases the crystallization degree of Li₂CO₃ products but also refines the grains. The optimal catholyte concentration of LiCl as the electrolytic parameter is 100g/L， ie， the concentration difference between anode and cathode liquid is 200g/L.

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Effect of Anode Geometry on Bubble Behavior in Aluminum Reduction Cell

HUANG Yi-peng， WANG Zhao-wen， YANG You-jian， SHI Zhong-ning

2019, 40 (2): 228-233. DOI: 10.12068/j.issn.1005-3026.2019.02.015

Abstract ( 720 )

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The behavior of anodic bubbles in the aluminum electrolytic cells is sensitive to the electrolysis parameters. So， transparent electrolysis cells are used to study the effects of inclined anode and rounded anode on the bubble behavior in a similar environment used in industrial cells. The results show that when the inclined angle is below 2°， the change in angle has little effect on bubble behavior， and when the inclined angle is above 2°， the bubble velocity increases significantly and the bubble size and coverage ratio decrease with the angle increasing. Moreover， "Fortin"-like bubbles are observed on the inclined anodes. The rounded anode reduces the bubble size and coverage ratio at a certain degree， while it does not promote bubbles releasing obviously.

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Experimental Study on Grinding Surface Processing Property of Nickel-Based Superalloy

CAI Ming， GONG Ya-dong， FENG Yao-li， LIU Yao-jia

2019, 40 (2): 234-238. DOI: 10.12068/j.issn.1005-3026.2019.02.016

Abstract ( 852 )

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Plane slot grinding single factor experiments of nickel-based single crystal superalloy DD5 and polycrystalline superalloy GH4169 were conducted in order to explore the grinding surface processing property of nickel-based superalloy. The influence of grinding wheel linear speed， grinding depth and feed rate on grinding surface quality was concluded. The grinding subsurface microstructure and grinding debris morphology were observed. The results show that: with the increase of grinding wheel linear speed， the grinding surface roughness R_○a decreases; with the increase of grinding depth and feed rate， the grinding surface roughness R_○a increases. With the same process parameters， the GH4169 is easier to machine and has better grinding performance than the DD5. With the increase of grinding wheel linear speed， a plastic deformation layer appears on the grinding subsurface and plastic deformation action is weakened gradually. The grinding debris mainly presents the serrated and crumbled features， and the serrated debris is dominant.

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Brittle Fracture Mechanism and Surface Roughness Model in Turning Fluorophlogopite Ceramics

MA Lian-jie， CAI Chong-yan， BI Chang-bo， ZHANG Li

2019, 40 (2): 239-244. DOI: 10.12068/j.issn.1005-3026.2019.02.017

Abstract ( 687 )

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The brittle fracture mechanism and surface formation mechanism are studied based on brittle fracture mechanics and tool-work piece interference principle in turning fluorophlogopite ceramics. The crack propagation angle and depth are predicted. The theoretical model of turning surface roughness is established to evaluate the surface quality of precision turning fluorophlogopite ceramics and improve the machining efficiency. The surface roughness in turning brittle materials consists of kinematical-geometrical roughness and brittle fracture roughness. Kinematical-geometrical roughness is mainly affected by tool geometry and feed rate， while brittle fracture roughness is mainly affected by cutting speed， cutting depth， cutting force and mechanical properties of ceramics. Experiment results show that surface roughness increases with the increase of feed rate and cutting depth， while decreases with the increase of cutting speed. Compared with the traditional geometric roughness model， the theoretical values of brittle model are closer to the experimental results， and theoretical values and experimental trends are identical.

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Analytical Modeling and Vibration Analysis of Hard-Coated Splitter Blisk

GAO Feng， SUN Wei， NI Chen-bing

2019, 40 (2): 244-250. DOI: 10.12068/j.issn.1005-3026.2019.02.018

Abstract ( 603 )

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The blades were coated with NiCoCrAlY+YSZ， then the dynamic model and vibration characteristics of the hard-coated splitter blisk were investigated， as well as the effect of hard coating on damping vibration reduction of the splitter blisk. Firstly， analytical model of the hard-coated splitter blisk was obtained using the complex modulus and the Oberst beam theories. The mode characteristics and forced responses of the hard-coated splitter blisk were then solved using the Gram-Schmidt process and Rayleigh-Ritz method. The results reveal that hard coating has a weak effect on natural frequencies of splitter blisk but makes the modal loss factors increase about four times， which explains that hard coating can effectively improve the damping performance of the splitter blisk. Moreover， the forced response can be suppressed remarkably.

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Simulation Analysis of Impact and Penetration for Small Celestial Body Penetrator

MENG Xiang-zhi， LIU Guang-ming， FU Li-xin

2019, 40 (2): 251-255. DOI: 10.12068/j.issn.1005-3026.2019.02.019

Abstract ( 664 )

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A prototype of a small penetrator was designed to provide a high-speed impact structure for lunar exploration. The advantages of this penetrator structure are lightweight， high stiffness and good vibration damping performance， which makes the penetrator effectively impact a small celestial body. The method of combining theory， numerical analysis and simulation was used for the analysis of the impact response of small penetrator and the penetration process of normal incidence and oblique incidence， so as to explore the needs of impact protection in the field of deep space exploration. The results show that the as-designed penetrator can effectively guarantee the existence of the internal components， and that the acceleration response of internal instrument module is less than the input value， which proves the effect of vibration damping. Moreover， the structure can protect the internal instrument so that it can work normally after the impact.

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H-O-S-Pb Isotopic Geochemical Characteristics and Formation Mechanism of the Herenping Gold Deposit

JIA San-shi， LENG Wen-fang， WANG En-de， GU Hong-fei

2019, 40 (2): 256-261. DOI: 10.12068/j.issn.1005-3026.2019.02.020

Abstract ( 552 )

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The geochemical analysis of H-O-S-Pb isotopes in the Herenping Gold Mine was carried out. The δ³⁴S values of sulfides from ore lie in-4.8‰~2.0‰. The ratios of ²⁰⁶Pb/²⁰⁴Pb，²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb from sulfide ores are 17.419~17.436， 15.519~15.535 and 37.86~37.90， respectively. The δD values of the fluid fall in-62.3‰~-53.0‰，and the δ¹⁸O values of the fluid are 4.2‰~11.8‰. These sulfur， lead， hydrogen and oxygen composition indicate that the ore-forming materials originate from the depth and the ore-forming fluid from magmatic hydrothermal， and mineralization has the characteristics of redox which formed the faded alteration zone in the region. Considering that the Herenping gold deposit is related to the deep magmatism， the ore prospecting should focus on the redox interface in the host strata and the faded alteration is the main indicator for the deposit.

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Reductive Transformation of Hematite to Magnetite with CO/CO₂ Under Fluidized Bed Conditions

YU Jian-wen， HAN Yue-xin， GAO Peng， LI Yan-jun

2019, 40 (2): 261-266. DOI: 10.12068/j.issn.1005-3026.2019.02.021

Abstract ( 588 )

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The reductive transformation behavior and kinetics of hematite to magnetite under fluidized bed conditions were studied by single mineral roasting test， isothermal reduction method and microstructure analysis. The results of reaction kinetics show that the selective reduction of hematite to magnetite with reductive fluidizing agent of 20wt%CO-80wt%CO₂ in a micro-fluidized bed reactor at 773-873K is controlled by formation of magnetite crystal nucleus and one-dimensional growth(A_3/2 model)， the apparent activation energy ΔE_a of the reaction is 49.64kJ/mol and the pre-exponential factor A is 6.55s^-1. The results of BET specific surface analysis and scanning electron microscopy measurement show that the fresh magnetite nucleus are dense needle-like structure with different lengths， and that as the reaction proceeds， the magnetite nucleus with the needle-like structure increases and aggregates to form porous magnetite particles.

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Formation and Control Technology of Ground Pressure of Gently Inclined Orebody in North Mining Area of Xishimen Iron Mine

SONG De-lin， REN Feng-yu， HE Rong-xing， CHANG Shuai

2019, 40 (2): 267-272. DOI: 10.12068/j.issn.1005-3026.2019.02.022

Abstract ( 554 )

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In order to formulate the ground pressure control measures for gently inclined orebody mining in north mining area of Xishimen Iron Mine， the ground pressure activity characteristic is summarized according to the field investigation. The ground pressure behavior of two sidewalls crashing and arch leg bending occurrs mainly around 35m in the hanging side of the mined-out area. The severity of ground pressure behavior decreases gradually with the increase of distance away from the upper goaf. The ground pressure behavior is consistent with the simulated ground pressure of the wedge body， which reveals that the ground pressure is caused mainly by the action of wedge body in the hanging side. The control measures are as follows: for ore body mining under the action of wedge pressure， the most suitable mining sequence is from the boundary of the mined-out area to the hanging side; the roadway should be perpendicular to ore body strike; arch supports with auxiliary sidewalls supports can control deformation effectively.

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Slope Failure Caused by Hanging-Wall Ores Mining by Induced Caving Method

REN Feng-yu， TAN Bao-hui， FU Yu， ZHU Qiang

2019, 40 (2): 273-278. DOI: 10.12068/j.issn.1005-3026.2019.02.023

Abstract ( 643 )

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Induced caving is a new underground mining method， which contributes to the smooth connection of ore production during the transition from open pit to underground. However， large scale of slope failure can be triggered when mining hanging-wall ores by this method， which would pose a threat to the open-pit mining， the open-pit transportation system and the surface infrastructure. The discontinuous geological structure of the rock mass is a key factor for slope stability. In this paper， the discontinuous deformation analysis(DDA)was used to study the slope failure process caused by hanging-wall-ore mining excavated by the induced caving method in different rock mass structures. Three slope failure modes， namely， sliding， toppling and complex failures， were concluded based on seven models with different rock mass structures， leading to different failure modes. A case of slope failure was analyzed based on Hainan iron mine. This study provides some technical supports for mining design of induced caving， as well as risk prediction and prevention of slope failure.

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Caving Mining of Steeply Inclined Narrow Veins and Supporting Mechanism of Caved Rock

AN Long， WANG Ri-dong， HOU Peng-yuan， LIANG Rui-yu

2019, 40 (2): 278-283. DOI: 10.12068/j.issn.1005-3026.2019.02.024

Abstract ( 830 )

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Based on the gold mine in Jinchanggouliang， taking advantage of the supporting role of caved rock， a caving mining method was proposed for steeply inclined narrow veins. Using numerical simulation method， the support mechanism action of caved rock for surrounding rock was studied and the influence of sublevel height on the supporting effect of caved rock was analyzed. The calculation results are as follows: the stability of surrounding rock increases significantly by the caving mining method compared with the open stope method and the volume of plastic zone decreases by 58.4%.With the increase of the sublevel height， the support effect of caved rock decreases slightly. The research result provides a new way for mining the broken orebody with steeply inclined narrow veins based on caving mining method. The feasibility and rationality of the caving mining method are also verified.

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Theoretical Calculation Model and Method of Transverse Joint of Precast Municipal Tunnel

WANG Peng-yu， WANG Shu-hong， JIERULA Alipujiang， LI Zhi-hua

2019, 40 (2): 284-289. DOI: 10.12068/j.issn.1005-3026.2019.02.025

Abstract ( 677 )

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Based on the performance test on the transverse joint of precast-prestressed municipal tunnel， the bending capacity and stiffness calculation models of the transverse joint are given according to the deformation coordination condition and the internal force balance equation， and the influence of prefabricated concrete strain， high strength bolt elongation and joint patchwork crack pattern are also considered in the models. The theoretical results are in good agreement with the existing test results， which verifies the correctness of the calculation model. The research results provide a theoretical basis for the safety evaluation and design optimization of precast-prestressed municipal tunnel.

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Innovation Capability Evaluation in Northeast China Considering Dual Development Trends

LI Wei-wei， YI Ping-tao， LIU Jun， JING Jing

2019, 40 (2): 290-294. DOI: 10.12068/j.issn.1005-3026.2019.02.026

Abstract ( 551 )

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The innovation indicators were selected from aspects of innovation fundamentals， innovation efficiency and innovation environment， and the innovation index was built based on the innovation indicators. Through analyzing the absolute and relative development levels of the innovation elements in 2011-2015， an evaluation model was proposed with the two development trends considered. It was found that the comprehensive innovation of Northeast China is comparatively poor. Although the absolute capabilities of innovation fundamentals， efficiency and environment have been improved， the relative capabilities exhibit a declining trend. Therefore， it should be warned that the decline of absolute innovation capability may result in the drop of the relative capability， and accordingly some policy suggestions are provided.

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SVM Model for Financial Fraud Detection

CAO De-fang， LIU Bai-chi

2019, 40 (2): 295-300. DOI: 10.12068/j.issn.1005-3026.2019.02.027

Abstract ( 861 )

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Based on the panel data of China’s capital market， the financial fraud companies from 2006 to 2015， together with the same number of non-fraud companies were selected as the research samples. Twenty-seven financial and non-financial indexes were analyzed， after which the dimension of the indexes was reduced through the test of independence and eight indexes were retained as the modeling parameters. The grid search algorithm， genetic algorithm and particle swarm optimization(PSO)were used respectively to optimize the parameters， and three support vector machine(SVM)models with the parameters optimized by the proposed methods were established respectively for financial fraud detection. The results showed that the SVM model with the parameters optimized by PSO has a higher detection rate than the other two models.

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A Second-Order Fuzzy Time Series Model for Stock Price Analysis

LIU Zhi， ZHANG Tie， DONG Ying， XU Shuang-shuang

2019, 40 (2): 300-304. DOI: 10.12068/j.issn.1005-3026.2019.02.028

Abstract ( 670 )

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It is difficult to model stock market because of its uncertainty， while fuzzy time series has its advantages in dealing with fuzzy and uncertainty data. Accordingly， the data was first preprocessed and a new way to divide the universe of discourse was given， after which the data was fuzzified using the triangular membership function， and a three-layer BP neural network was then established according to the fuzzified data. Finally， the generalized inverse fuzzy number formula was used to defuzzify the fuzzy relation， with the prediction results obtained. The method was used for predicting the stock price of State Bank of India(SBI)and the enrollment of the University of Alabama， and the results showed that the prediction accuracy is higher than that of the related previous methods.

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