Journal of Northeastern University(Natural Science)

Multimedia Sensor Networks Coverage Enhancing Algorithm Based on 3D Perception

ZHUANG Yao-ming， WU Cheng-dong， ZHANG Yun-zhou

2018, 39 (5): 609-613. DOI: 10.12068/j.issn.1005-3026.2018.05.001

Abstract ( 686 )

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Existing optimization algorithms of wireless multimedia sensor networks (WMSMs) are easy to fall into local optimal solutions. The cuckoo search algorithm， by using a long distance search， can jump out of local optima effectively. This algorithm is based on the 3D perception model. The ratio of coverage is improved by introducing elite mechanism， multi-dimensional optimization and learning-feedback strategy to optimize the angle of rotation and reduce overlap. The improved cuckoo search made the first attempt to optimize the network coverage in MSNs. Finally， the simulation results show that the ratio of coverage is improved by the proposed algorithm.

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Energy Conservation Strategy for Wireless Multimedia Sensor Networks Based on Visual Correlation

YANG Xiao-tao， WEN Ying-you， CHEN Ji-yang， ZHAO Hong

2018, 39 (5): 613-618. DOI: 10.12068/j.issn.1005-3026.2018.05.002

Abstract ( 827 )

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In order to reduce the energy consumption in resource-constrained homogeneous camera wireless multimedia sensor networks(WMSNs)， the visual correlation algorithm was developed and a novel fully distributed energy conservation strategy based on the developed visual correlation algorithm was proposed. Firstly， the visual correlation vector was calculated by the visual correlation algorithm. Then， the competition chips were obtained by applying the visual correlation vector， thus the role of camera was determined. After that， two parallel and interactive operations were executed: the cluster head nodes determine its own next-hop and establish the route according to the weight vector; the non-cluster head nodes obtain its own cluster ID by calculating the intimacy vector. Finally， experimental results demonstrate that the proposed strategy can effectively prolong the network lifetime in resource-constrained wireless multimedia sensor networks.

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Improved SLM Algorithm for Reducing OFDM System Complexity

JI Ce， JIA Dian-xia， ZHANG Chao， ZHU Wen-jing

2018, 39 (5): 619-623. DOI: 10.12068/j.issn.1005-3026.2018.05.003

Abstract ( 754 )

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In order to reduce the computational complexity of the traditional selective mapping(SLM)algorithm in OFDM(orthogonal frequency division multiplexing) systems， and improve the spectral efficiency of the system， a CR-SLM algorithm based on the combination of conversion vectors and random selection sequences was proposed. In this algorithm， the data sequence is equally divided into two parts. For the first half of the data sequence IFFT(inverse fast Fourier transform) is taken， and then circular convolution is performed. Random sequence screening is applied for the second half section to reduce the complexity. Finally， the two output sequences are grouped together to generate candidate sequences， and the optimal sequence is selected for transmission. The simulation results show that the CR-SLM algorithm greatly reduces the computational complexity while maintaining the PAPR(peak to average power ration) close to that of the conventional SLM algorithm.

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Dynamic Recrystallization Behaviors of Ti Micro-alloyed 510L Steel for Automobile Frame

ZHOU Xiao-guang， CHEN Qi-yuan， LIU Zhen-yu， WU Si-wei

2018, 39 (5): 624-629. DOI: 10.12068/j.issn.1005-3026.2018.05.004

Abstract ( 633 )

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The dynamic recrystallization behaviors of Ti micro-alloyed 510L steel for automobile frame were investigated using single-pass compression tests and hot-rolling and quenching tests for step samples. The results show that when the strain rate is 0.1s^-1， the dynamic recrystallization can occur at the deformation temperature ranging from 850 to 1050℃; while， when the strain rate is 0.2s^-1， it only occurs at the temperature above 950℃.With increasing the deformation temperature and strain， the average grain size of the austenite decreases and the volume fraction of recrystallization increases. By regression analysis， the activation energy for dynamic recrystallization in the tested samples is 211.43kJ/mol， which indicates that the addition of Ti has little effect on dynamic recrystallization behavior of the high-temperature austenite. The critical strain and kinetic models for dynamic recrystallization are also established.

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Effects of Two-Step Annealing and Initial Grain Size on the Grain Boundary Character Distributions of Hastelloy C-276

ZHANG Xiao-yu， ZHAO Xian-ming， LI De-fu， GUO Sheng-li

2018, 39 (5): 630-633. DOI: 10.12068/j.issn.1005-3026.2018.05.005

Abstract ( 625 )

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Hastelloy C-276 samples with different initial grain sizes were subjected to one-step and two-step annealing heat treatments after cold-rolling process and their grain boundary character distributions (GBCDs) were characterized by electron backscatter diffraction (EBSD) techniques. The results show that the large-sized initial grains tend to optimize the GBCD. Compared with that in the small-sized grain ones， the fraction of coincident site lattice (CSL) boundary in Hastelloy C-276 samples with large-sized initial grains increases nearly 10%， which is up to 78.8%. Meanwhile， the clusters with average size of 200μm are formed. For the samples with same-sized grains， the GBCD can be well improved by the two-step annealing treatment， where the fraction of ∑3^○n boundaries can be increased significantly and the better clusters can be formed. The more incoherent ∑3 boundaries， the more ∑9 and ∑27 boundaries can be generated， leading to the more triple junctions. Therefore， the connectivity of the high-angle grain boundary network is disrupted effectively.

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Bubble Breakup and Coalescence in Electromagnetic Stirring Ladle

GOU Da-zhao， LEI Hong， GENG Dian-qiao

2018, 39 (5): 633-637. DOI: 10.12068/j.issn.1005-3026.2018.05.006

Abstract ( 675 )

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A mathematical model for the gas-liquid flow field in the ladle with argon blowing and electromagnetic stirring was developed based on the Euler model and population balance model(PBM). The results show that the upward stirring only forms a large circulation flow field in the ladle， while the downward stirring forms a large and a small circulation flow fields. The size of the bubble in the center of gas-liquid region is the largest and is gradually reduced when the bubble is changed from the center to the boundary of the gas-liquid two-phase region. With increasing electromagnetic stirring current， the deflection degree in vertical direction in gas-liquid two-phase region is greater and the distribution of large-sized bubble area in the center of the gas-liquid two-phase region becomes wider. The area of large-sized bubbles in the central region from the downward stirring is smaller than that from the upward stirring. The spatial distribution of large-sized bubbles has less effect on the deflection and bends to the center line of the ladle.

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Thermodynamics and Dynamics of Ti-6Al-4V Alloy Preparation by Thermite Reduction

CHENG Chu， DOU Zhi-he， ZHANG Ting-an， YI Xin

2018, 39 (5): 638-642. DOI: 10.12068/j.issn.1005-3026.2018.05.007

Abstract ( 813 )

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The thermodynamics and dynamics of Al-TiO₂， Al-V₂O₅， Al-V₂O₅-TiO₂， Al-V₂O₅-TiO₂-CaO systems were studied. The results indicate that the method for preparing Ti-6Al-4V alloy by reducing TiO₂ and V₂O₅ with Al powder is feasible. The addition of CaO can decrease the reaction heat per unit mass of the system， therefore， it requires the heat supplement to maintain the reaction. It is found that the reaction of TiO₂ reduced by Al for preparing Ti-6Al-4V alloy occurs at 951℃， where the apparent activation energy is 166.47kJ/mol and the reaction order is 0.3982， and the reaction of V₂O₅ reduced by Al occurs at 946℃， where the apparent activation energy is 392.72kJ/mol and the reaction order is 1.0618. It is also shown that the reaction of TiO₂ and V₂O₅ reduced by Al occurs at 1019℃， where the apparent activation energy is 173.56kJ/mol and the reaction order is 0.4722， while after the addition of CaO， the reaction can occur at 979℃， associated with a higher apparent activation energy and lower reaction order. All the four reactions belong to the liquid-solid reactions.

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Heat Transfer in a Retort for Mg-Extraction by Pre-prepared Pellet Silicothermic Process

FU Da-xue， ZHANG Ting-an， DOU Zhi-he， GUAN Lu-kui

2018, 39 (5): 643-648. DOI: 10.12068/j.issn.1005-3026.2018.05.008

Abstract ( 668 )

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A novel method of feed preparation for silicothermic process was proposed in order to solve low efficiency of heat transfer in Pidgeon process. In this method， dolomite and ferrosilicon were mixed to produce pellets and then were calcined. The pre-prepared pellets were charged into the retorts for Mg extraction at once after calcinations. Heat transfer in a retort for the novel process was investigated by a numerical method. The results show that a better heat transfer can be obtained by increasing the amount of Si-Fe addition， pellet diameter or decreasing the packed bed density. The time for heating the center of the retort into 1473K decreases from 300min to 178min， after increasing the boundary temperature from 1473K to 1498K. In a retort of 300mm diameter， the heating time is 90min for the center of the retort charged by pre-prepared pellets of 25mm diameter reaching 1473K， compared with that of 288min in Pidgeon process.

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Physical Simulation of Emulsion Phenomena in Copper Side-blown Smelting Process

LI Xiao-long， LIU Yan， WANG Dong-xing， ZHANG Ting-an

2018, 39 (5): 649-653. DOI: 10.12068/j.issn.1005-3026.2018.05.009

Abstract ( 666 )

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In order to quantitatively describe the emulsion phenomena， a physical model was built up based on the similarity law. Then a high-resolution camera and Image Pro-Plus 6.0 software were utilized to record the emulsion phenomena and analyze the effect of gas flow rate on the emulsified drops size distribution. Finally， an estimation method of the interfacial area ɑ was given. The results show that the Sauter mean diameter (SMD) of emulsified drops decreases with the increasing of gas flow rate. The interfacial area of emulsion layer almost linearly increases with the gas flow rate and the separation of matte and slag is caused by gravity and mass transfer.

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Research on Reactive Optimization of Biomass Fuel Based on Sintering

LIU Chao， ZHANG Yu-zhu， XING Hong-wei， KANG Yue

2018, 39 (5): 654-658. DOI: 10.12068/j.issn.1005-3026.2018.05.010

Abstract ( 684 )

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The exothermic reaction of biomass fuel is too fast， causing a heat mismatch between flame front and wave front， which can greatly affect the performance of the ore sintering. In this work， the CaO powder will be filled in the pore of biomass fuel and the “package granulation” will be used to make a modification of biomass fuel in order to optimize the reaction. The differential thermal and thermo gravimetric results of modified fuel are compared with those of coke breeze. The experimental results show that the exothermic reaction temperature of the biomass fuel modified by CaO powder increases to 382.09℃ and the exothermic inflection point temperature increases to 395.23℃， and the differential thermal curve moves back and delays thermal release. As to the biomass fuel modified by the “package granulation” in the sintering mixture， the weightlessness temperature increases to 462℃， the weight loss time is prolonged， and the weight loss curve closes to that of coke powder.

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Effects of Chemical Modified Gas-Generating Agent on the Properties of Aluminum foam

GUO Lei， XIAO Lai-rong， ZHAO Xiao-jun， SONG Yu-feng

2018, 39 (5): 658-662. DOI: 10.12068/j.issn.1005-3026.2018.05.011

Abstract ( 765 )

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The aluminum foam was prepared by melt foaming method using chemical modified TiH₂ as gas-generating agent and the effect of the TiH₂ addition on the porosity， compressive and damping properties of aluminum foam was studied. The results show that using chemical modified TiH₂ as gas-generating agent can increase the starting temperature of releasing H₂ from 480℃ to 550℃ and decrease the rate of releasing H₂.With increasing the TiH₂ addition， the porosity of aluminum foam increases， the compressive stress decreases and the damping property firstly increases and then decreases. When the mass percentage of the TiH₂ addition is 1.5%， the porosity of aluminum foam is up to 88%， the size and distribution of pores are uniform， and the compressive and damping properties of the foam are well improved.

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Impact-Energy Principle Resembling Master Curve Model of Q390 Steel in Transition Temperature Region

KONG Xiang-wei ， LI Xu-qing， LAN Liang-yun， YUE Meng-long

2018, 39 (5): 663-667. DOI: 10.12068/j.issn.1005-3026.2018.05.012

Abstract ( 687 )

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The impact energy distribution law of Q390 low-alloy and high-strength steel in transition temperature region was investigated by using the Charpy impact test， the idea of the Master Curve method and the empirical correlations between impact energy and fracture toughness. The Master Curve reference temperature was obtained by the Charpy impact tests. And then the Master Curve expression of Q390 steel was regressed from the Master Curve reference temperature. Besides， considering the influence of the thickness of impact specimen， the impact-energy principle resembling Master Curve distributive model of Q390 steel in transition temperature region was finally acquired by combining the empirical correlation which was most suitable for Q390 steel. The results show that this model fairly describes the relationship among the impact energy， the temperature and the cumulative failure probability in transition temperature region of Q390 steel， and expands the application of the Master Curve method to a certain extent.

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Modeling and Evaluation of the Mating Error Influences to the Fatigue Life of a Electrical Connector

YANG Qiang， DAI Peng-fei， QIU Hao， SUN Zhi-li

2018, 39 (5): 668-673. DOI: 10.12068/j.issn.1005-3026.2018.05.013

Abstract ( 733 )

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Taking a certain type 22^# pin jack electrical connector as the research object， the strain-life equation of the contact material was established based on the Brown-Miller correction criterion. The mechanical properties of a single insertion and extraction process of the contact part were calculated by finite element method and the contact fatigue life model of the contact part was established based on the Fe-Safe software. Then the quantitative evaluation of the influence of the mating error to the fatigue life of the electrical connector is completed. The results of fatigue life analysis show that the maximum displacement error is 0.038mm， the angle error is 0.621°， and the compound error is 0.03mm and 0.405°under the designed life condition. According to the results， detail fatigue life improving suggests for the electrical connector are proposed， the result provides a theoretical basis for the manufacturing and control of assembling errors and process improvement for the connector.

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Stability Analysis of Walking on the Slope for a Quadruped Robot

MA Zong-li， ZHANG Pei-qiang， LYU Rong-ji， WANG Jian-ming

2018, 39 (5): 673-678. DOI: 10.12068/j.issn.1005-3026.2018.05.014

Abstract ( 784 )

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The hydraulic cylinders were adopted for building the quadrupeds shins. In order to improve the locomotion stability on the slope， a mass center adjusting method by increasing the length of the rear shins and decreasing the length of the front thins was proposed. The kinematics of the quadruped robot was analyzed. The relationship between the adjustment length of the front shins and rear shins as well as the slope angle were calculated. By using Adams and Matlab， the coordinated simulation of the robot was performed. The simulation results show that the robot is capable to move steadily on the slope with trot gait. The effectiveness of adjusting the center of mass of a quadruped robot is verified.

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Quantitative Measurement of Vibration Localization of Blisk with Damping Coating Based on Experimental Mode

SUN Wei， FAN Yun-fei

2018, 39 (5): 679-683. DOI: 10.12068/j.issn.1005-3026.2018.05.015

Abstract ( 643 )

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Vibration control of blisk by attaching damping coating is a new technique. To implement this technology effectively， it is necessary to measure the degree of vibration localization of blisk for different coating schemes. Based on experimental modal data， a quantitative measurement method for the vibration localization of blisk is proposed. Firstly， the theory of quantitative measurement of the degree of vibration localization was proposed， and the reasonability was verified. Then， the procedure of quantitative measurement of vibration localization of blisk with damping coating was presented. Lastly， the vibration localizations of blisk with three coating schemes were tested. The results showed that the developed method can effectively measure the vibration localization of blisk with different coating schemes and the degree of vibration localization of blisk becomes more evident and fluctuates with the increase of coating area.

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Quantum Chemical Study of the Adsorption of NaOL on Cassiterite(211) Surface

GONG Gui-chen， HAN Yue-xin， LIU Jie， ZHU Yi-min

2018, 39 (5): 684-688. DOI: 10.12068/j.issn.1005-3026.2018.05.016

Abstract ( 754 )

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The adsorption of NaOL on cassiterite (211) surface was studied by first-principles calculations based on density functional theory. The rationality of the simulated cassiterite bulk cell was confirmed by comparing the numerical and experimental XRD patterns. Stypticity test results show that cassiterite (211) surface is stable when the slab thickness exceeds 5.437×10^-10m and the vacuum depth surpasses 10×10^-10m. Adsorption energy calculation results suggest that H₂O and OH^- can adsorb on the (211) surface spontaneously， but the affinity of OL^- with cassiterite (211) surface is the strongest， implying it can replace the adsorbed H₂O and OH^- species on (211) surface. Mulliken charge calculations and differential electron density analyses demonstrate the two O atoms in oleate carboxyl are bonded with two exposed Sn atoms on the surface during the interaction， resulting in chemisorption with the stronger bond formed by the single bond O and Sn atom.

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Characteristics of Trace Rare Earth Elements of Xiaotongjiapuzi Gold Deposit

WEI Jun ， WANG En-de， MEN Ye-kai， HE Qiang-wen

2018, 39 (5): 689-693. DOI: 10.12068/j.issn.1005-3026.2018.05.017

Abstract ( 645 )

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The trace rare earth elements of rocks and ores in Xiaotongjiapuzi gold deposit was analyzed to discuss the mineral sources and the effect of Indosinian-Yanshan magmatic activities on mineralization.Gaixian Formation schists and Dashiqiao Formation marbles exhibit similar variation trends of trace elements and rare earth distribution patterns， and Indosinian granite showed little difference in trace elements such as P， Zr and Hf， et al.Lyuliang-Yanshan period magmatic rock mass lacked Er， reflecting that gold mineralization was closely related to the strata and magmatic rocks. Characteristics of rare earth elements suggested that the ore-forming hydrothermal was a reductive fluid rich in Cl^-， and metallogenic material source and ore-forming fluid source was complex.Lyuliang period granite， Yanshan period granite， Gaixian Formation schists and Dashiqiao Formation marbles all provided ore-forming material for the formation of ore bodies， and deep metallogenic material participated in the mineralization.Xiaotongjiapuzi gold deposit is a magmatic hydrothermal superimposition type gold deposit.

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Evolution Analysis of Microbial Community During the Running Process in an ANAMMOX Reactor

ZHU Tong， JIA Ruo-tan， LIANG Qi-yu， XIE Yuan-hua

2018, 39 (5): 693-698. DOI: 10.12068/j.issn.1005-3026.2018.05.018

Abstract ( 700 )

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In order to provide theoretical support for the optimization of anaerobic ammonium oxidation (ANAMMOX)technology， high-throughput sequencing technology was used to study the microbial community structure and its evolution in an ANAMMOX reactor. The results showed that the reactor achieved nitrogen removal rate up to 1.04kg·N·m^-3·d^-1 after 61 days. The total nitrogen removal rate was above 75%.The microbial diversity in the reactor was very abundant，including Proteobacteria，Chloroflexi， Chlorobi，Planctomycetes， etc.The microbial community structure tended to be stable with the running process of the reactor.The proportion of Proteobacteria and Planctomycete， associated with denitrification， totally achieved over 40%. The proportion of ANAMMOX bacteria belonging to Planctomycete increased gradually with reactor operation， which was the main reason for denitrification efficiency improvement.The ANAMMOX bacteria Candidatus Kuenenia category dominated in reactor about 14%. A small number of Candidatus Brocadia genus also existed in the reactor.

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Stability Evaluation of Surrounding Rock and Parameter Optimization of Stope Under Complex Stress Disturbance

ZHANG Fei， YANG Tian-hong， HU Gao-jian

2018, 39 (5): 699-704. DOI: 10.12068/j.issn.1005-3026.2018.05.019

Abstract ( 578 )

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The Xiadian gold mine has already experienced the deep mining， the stope by the caving method and filling method is affected by multiple disturbance stress. It is very important to determine the reasonable stope size and the stability of surrounding rock for the safety operation of the mine. The parameters of discontinuities around the experimental stope were obtained by using the advanced photogrammetry technique， and the stability of surrounding rock mass of the experimental stope was evaluated by multi-method. On the basis of this， the parameters of the stope are optimized by using the Mathews method and the span experience formula. Finally， through the numerical simulation， the rationality of the obtained experimental stope size is analyzed and verified. The successful application of the optimized stope size in the mine designed by Mathews method， verified the feasibility of the graphic method in the design of the stope size under complex stress.

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Graphic Discrimination Method of Coalescence and Failure Mode in Rock Mass with Hole and Crack

WANG Shu-hong， ZHANG Yu-nong， HUANG Li-fu， XIAO Fu-kun

2018, 39 (5): 705-709. DOI: 10.12068/j.issn.1005-3026.2018.05.020

Abstract ( 666 )

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In order to study the crack initiation and coalescence of the failure process of rock mass， the uniaxial compression of red sandstone samples with various rock bridge angles was numerically performed. Four failure patterns of red sandstone samples with single crack and hole is firstly summarized， then the radius of the plastic core and plastic extension area are defined， the single span radius (or the crack length， angle) and the size of the plastic damage area are characterized. It is found that the coalescence of plastic failure zone is well consistent with the coalescence and fracture of samples. Finally， a graphic discrimination method is proposed to discriminate the fracture mode of rock mass. The experimental results verify the correctness of the method of the failure mode， which is consistent with the results of similar physical tests.

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Experiment Comparison on Microwave Radiation from Stressed Rock Covered by Materials: Dry or Humid Sands

MAO Wen-fei， WU Li-xin， LIU Shan-jun， XU Zhong-yin

2018, 39 (5): 710-715. DOI: 10.12068/j.issn.1005-3026.2018.05.021

Abstract ( 629 )

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Considering the working conditions of satellite sensors in earth observation， the loading experiments of rock under the condition of cold sky background were carried out. The influence of cover layers on microwave radiation from loaded bare rock in elastic phase is analyzed， and the influence mechanism is discussed as well. The horizontal loading machine and C band microwave radiometer were applied for observing the microwave radiation from the stressed granite samples covered by different materials: dry or humid silver sands. The experimental results show good synchronicity between the microwave radiation and the loaded stress in the elastic deformation phase of granite samples， which with the correlation coefficient of 0.94 and the microwave brightness increases by 0.015K/MPa. When covered by dry or humid sands(with layer thickness of about 2.5cm)， the characteristics of affected microwave radiation from the stressed rock are much different: 1)the dry sand has no obvious influence on the affected microwave radiation from stressed rock; 2)the humid sand weakens the signals received by microwave radiometer significantly.

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Ultimate Metal Pit Optimization with Various Wall Slope

XU Xiao-chuan， GU Xiao-wei， WANG Qing， ZHANG Wei-feng

2018, 39 (5): 716-721. DOI: 10.12068/j.issn.1005-3026.2018.05.022

Abstract ( 773 )

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Based on the moving cone method， the ultimate pit of Nanfen open pit mine was optimized and the influences of hanging wall angle variation on the pit shape， ores and rocks were studied. According to the mining states in different periods， related technical and economical parameters were set to optimize initial pit. The ultimate pits were optimized by increasing the hanging wall slope with the step of 0.5°. The results show that the ranges of ultimate pit shrink gradually and the bottom sizes become larger or downward with wall slope steeping. The ore-rock volumes of ultimate pits obtained by various steeping wall slope may increase or reduce， and the cost may increase， but the total profits increase.

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Mined-Out Area Treatment Method by Surface Filling Under Open-Pit Slope Adjacent to Tailing Reservoir

REN Si-tong， GU Xiao-wei， FU Yu， LI Chuan-ying

2018, 39 (5): 722-725. DOI: 10.12068/j.issn.1005-3026.2018.05.023

Abstract ( 674 )

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Aimed at solving high cost， poor safety and extreme difficulty caused by conventional mined-out area treatment by waste rock filling， innovative mined-out area treatment method was studied by inducing and controlling caving as well as surface collapse pit filling， used in Paishanlou gold mine. The innovative methods including using of RG underground television monitoring and evaluation on mined-out area caving process， drilling from the surface protecting the open pit tailings reservoir， blasting ore pillar and inducing the emit through earth′s surface， recovering landform by filling collapse pit from the surface and land forming by alien earth and recovery surface function. The application of this innovative method in Paishanlou gold mine enables safe and efficient filling treatment of large-scale active mined-out area， and achieve good economical and technical results. Both theoretical analysis and practice shows that， for open-pit slope adjacent to the tailings reservoir of inclined ore body mined-out area， using controlled induced caving and surface filling method will reduce the difficulty of mined-out area waste rock filling treatment， and ensured safe and efficient treatment of large-scale mined-out area.

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Three-Dimensional Modeling Method of Coal Seam with Gradual Refinement

JIA Qing-ren， CHE De-fu， LI Jia-xu， CHEN Kai

2018, 39 (5): 726-730. DOI: 10.12068/j.issn.1005-3026.2018.05.024

Abstract ( 736 )

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The existing coal seam modeling methods using discrete points or geological boundaries from multi-source data lack enough attention to the dynamic changes of coal seam in the mining process. A new 3D coal seam fine modeling method is proposed. Firstly， creating regional grid of the mining area and converted to triangulated irregular network (TIN)，inter polating attributes of TIN nodes (elevation and thickness)using ordinary Kriging method，and then a generalized tri-prism(GTP) model of coal seam will be built as the initial model. Secondly， the initial model is refined gradually by the dynamic data within the influence domain of these data. A prototype system is created and implemented in Qianjiaying coal mine， Tangshan， China. The result shows that this method can accurately reflect the change of 3D coal seam model from the dynamic data， thus the accuracy of the 3D coal seam model can be improved gradually.

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Influencing Factors and Inhibition of Hydrogen Produced by Aluminum and Water Reaction

WANG Yan-tong， XU Kai-li， LI li， WANG Ben

2018, 39 (5): 731-735. DOI: 10.12068/j.issn.1005-3026.2018.05.025

Abstract ( 825 )

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Aluminum particles could react with water and produce hydrogen， and there is the risk of hydrogen explosion.Through the aluminum water reaction tester， the effect of different mass ratio of aluminum to water and different temperature on the hydrogen production and maximum production rate were systematically studied. A new method， PSM， is proposed to suppress hydrogen production from aluminum hydrate. The aluminum particles before and after the reaction were characterized by SEM， XRD and EDS. The mechanism of the reaction is clarified. The low cost PSM method can effectively inhibit hydrogen production， and it also could provide the inherent safety method for the hydrogen inhibition in some engineering project.

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Analysis of Gas Explosion Accidents Based on Socio-technical System Theory

ZHANG Jin-jia， XU Kai-li， LI Li， XU Qing-wei

2018, 39 (5): 736-740. DOI: 10.12068/j.issn.1005-3026.2018.05.026

Abstract ( 633 )

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The impact of social environment on coal enterprise was analyzed based on the perspective of socio-technical system theory. On this basis， causation analysis model of gas explosion accidents for socio-technical system was established to investigate the interaction correlation from five levels of risk source， operation situation， coal enterprise， administration departments and government， and put forward the measures of administration intervention， technology control and multiple defense system. The results show that risk control of socio-technical system exists in the leakage phenomenon and hierarchy weakened defects， and gas explosion accident is the result of interaction with the internal and external environment.

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Sensitivity Analysis of Static Parameters About Deformation in Pastor-Zienkiewicz Sandy Model

LI Chun， XIU Zhan-guo， WANG Fei-li， WANG Qiu-hong

2018, 39 (5): 741-745. DOI: 10.12068/j.issn.1005-3026.2018.05.027

Abstract ( 610 )

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Based on the theory of generalized plasticity， for static Pastor-Zienkiewicz(P-Z) model parameters， it can be divided into eight parameters from three aspects. The sensitivity analysis of vertical displacement varying with each parameter was performed. The results showed that elastic modulus E exhibits the largest sensitivity， and the corresponding maximum rate of vertical displacement is 66.05%， when the every parameter is changed between -40%~40%. Followed by the angle of internal friction φ and Poisson’s ratio μ， the rate of vertical displacement was within ±10%. But for the parameters about plastic modulus， the rate of vertical displacement was less than ±1%. When lack of measured data， the values of plastic parameters can come from a great amount of geological data. The conclusions can provide important basis for the selection of P-Z sandy model parameters in the deformation calculation of sub grade.

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A Group Evaluation Method Based on the Convincing Force of Evaluators

GONG Cheng-ju， GUO Ya-jun， ZHENG Hong， LI Wei-wei

2018, 39 (5): 746-749. DOI: 10.12068/j.issn.1005-3026.2018.05.028

Abstract ( 567 )

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Aimed at how to determine expert weights in group evaluation， a group evaluation method based on the convincing force of evaluators was proposed from the perspective of the attention degree of expert information in order to improve the credibility of evaluation results. It was found that this method not only guarantees the completeness of evaluators’ evaluation information， but also integrates evaluators’ experience information and other information in the evaluation process to ensure the accuracy of evaluation results. Firstly， the evaluation context was set and the research hypotheses were made， and then a distinction between evaluators and evaluation requestors was made. Secondly， the computational model of convicing force was constructed and its validity was expounded upon. Finally， a nonlinear programming model was used to calculate the final evaluation result of every evaluated object.

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Supply Chain Pricing Strategy Based on Product Life Cycle Under Risk-Aversion

PANG Wei-hong， CHEN Wei-hua， LI Kai， YUAN Hong-tao

2018, 39 (5): 750-755. DOI: 10.12068/j.issn.1005-3026.2018.05.029

Abstract ( 634 )

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Based on the product life cycle， the mean-variance method was adopted to investigate the supply chain pricing strategy. According to the demands in different periods of product life cycle， different decision-making functions were firstly constructed， then the pricing strategies of supply chain in different periods were analyzed， and finally the optimal retail price， wholesale price and operating performance were provided. It was revealed that the retailer price becomes lower and the wholesale price is higher when retailers’ risk aversion increases; the retail price and wholesale price become lower when manufacturers’ risk aversion increases; and the market position becomes more stable and the price of manufacturers and retailers becomes higher when the product life cycle is longer.

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A Coordinative Contract of the Dual-Channel Closed Loop Supply Chain with Two-Sale Periods Considering Rate of Recovery

YU Chun-hai， LIU Shan-shan， RONG Dong-ling， LI Yi-duo

2018, 39 (5): 756-760. DOI: 10.12068/j.issn.1005-3026.2018.05.030

Abstract ( 656 )

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A coordinative contract based on a two-stage supply chain pricing model consisting of a manufacturer and a retailer was studied. The model divided the entire sale period into two-sale periods and sells the product through a dual channel. There exists the Stackelberg game behavior which is dominated by the manufacturer among the supply chain members. The game theory was used to establish the decision-making model and an improved revenue-sharing contract was introduced to solve the channel conflict. The results showed that the e-channel can lead the retailer to raise the market price when manufacturer maintain traditional channels， which may adversely affect the overall market demands causing the decrease of overall profits. The channel conflict may ensue when the rate of recovery is lower under specific strategies. In order to solve the conflict of the mixed dual channel， an improved contract of wholesale price and revenue sharing contract was designed， which not only achieves the coordination of the dual-channel supply chain， but also helps the supply chain members to get Pareto improvement in their profits.

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