Journal of Northeastern University(Natural Science)

Observer Design for Stochastic Markov Switching Systems with Actuator Saturation

GAO Xian-wen， DU Jin-ming， QI Wen-hai

2016, 37 (1): 1-5. DOI: 10.12068/j.issn.1005-3026.2016.01.001

Abstract ( 701 )

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The direct approach was used to study the stochastic Markov switching system with partly unknown transition probabilities and actuator saturation considering the problem of stochastic stability analysis. Through using free connection weight matrix， the conservation of the system would be decreased. Firstly， for stochastic Markov switching systems， by considering the properties of the relationship between the transition probabilities， the observer was designed to guarantee the stochastic stability of the closed-loop saturated system based on the parameter-dependent Lyapunov function. And then， the largest contraction invariant set in the mean square sense was proposed in the framework of linear matrix inequalities (LMIs). Finally， a numerical example was given to demonstrate the effectiveness of the method.

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Instability and Chaos of Smart Grid

YANG Jun， WANG Ya-guang， SUN Qiu-ye， ZHONG Rui

2016, 37 (1): 6-10. DOI: 10.12068/j.issn.1005-3026.2016.01.002

Abstract ( 767 )

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A large number of distributed new energy incorporated in the grid through inverters is one of the characteristics of smart grid， resulting in the change of the power flow and the voltage distribution characteristics of smart grid， which will influence the stability of the smart grid. A dynamic model to analyze the process of instability and chaotic behavior of smart grid was firstly presented by using droop control strategy， equivalent generator and dynamic load model. With the simulation results， the asymptotically stable， cycle operation， quasi-periodic operation， chaos， hyperchaos and voltage collapse could be obtained under different initial conditions in smart grid. And it was found that the bifurcation， chaos， hyperchaos and voltage collapse were the middle processes of instability in smart grid. To prevent the instability accidents， the timely and effective control should be taken before the critical point.

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Flow Pattern Identification of EMT Based on Signal Sparseness

WANG Jing-wen， WANG Xu

2016, 37 (1): 11-14. DOI: 10.12068/j.issn.1005-3026.2016.01.003

Abstract ( 561 )

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In view of lower recognition rate of traditional methods in flow pattern identification of electromagnetic tomography (EMT)， a flow pattern identification method of EMT was proposed based on signal sparseness. On the base of Maxwell’s electromagnetic induction equations principle，Comsol multiphysics software was used for the simulation of EMT system， which was composed of eight electromagnetic sensors. Firstly， simulation models of several flow pattern were established and the voltage values were measured， and the measurement voltages were normalized and represented as the basis of identification of electromagnetic tomography (EMT) as well.Then normalized voltage was represented as a sparse combination. Finally，the optimal solution was obtained to realize flow pattern. The experimental results show that the method can identify circulation， the core flow， etc.， and the recognition rate is higher， which is worthy of further research and extension methods.

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Research for Impacting Parameters Algorithm on Cylindrical Aerial Target

LIANG Zhen-gang， JIANG Jian-wei ， CHEN Feng

2016, 37 (1): 15-19. DOI: 10.12068/j.issn.1005-3026.2016.01.004

Abstract ( 603 )

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Whether to calculate the impacting parameter accurately and efficiently which is about the kill element against the air target not only plays an important role in evaluating the kill probability of ammunition for aerial targets， but also plays an important indicator to assess the operational effectiveness of the missile weapon system. Based on the analysis of kill element and target motion model， methods of discreting cylindrical target into multiple small rectangles were proposed， and the angle calculation methods on the velocity direction of impacting and the axial section，cross section of the target，target angle and the target speed were deduced by using the judging criterion on hitting the target according to the relation between the distance of the intersection point to the four sides of the rectangle and the perimeter. And then the correctness and accuracy of the algorithm were verified by an example. The algorithm serves as basis for further studying the impacting parameter which is about the kill element against the aerial target.

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The Small Signal Stability for Transmitting Wind Power Bundled with Thermal Power

CAO Xi-min， LIU Tian-qi， LI Xing-yuan，LI Cong-shan

2016, 37 (1): 19-23. DOI: 10.12068/j.issn.1005-3026.2016.01.005

Abstract ( 686 )

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In order to research the small signal stability of wind-thermal bundled transmission system， the small perturbation analysis model of wind-thermal bundled transmission system was established， which included wind turbine， pitch angle control system， converter control system， the induction generator. The small signal stability analysis method of the wind-thermal bundled system was introduced in detail. The system eigenvalues of wind-thermal bundled transmission systems with different wind power access， wind power output level， wind-thermal allocation ratio and delivery line length were calculated under the simulation system of wind-thermal bundled transmission established. The simulation results showed that the weaker the relationship between wind power and the power system was， the worse the small signal stability of wind power was. In addition， the small signal stability of the system would be directly impacted by the wind power output level and wind-thermal allocation ratio.

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A Top-k High Utility Itemset Mining Method Based on the Index Utility

LIN Shu-kuan， WANG Xiao-cong， QIAO Jian-zhong， WANG Rui

2016, 37 (1): 24-28. DOI: 10.12068/j.issn.1005-3026.2016.01.006

Abstract ( 562 )

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The existing methods of Top-k high utility itemset mining substitute the transaction utilities of itemsets for their real utilities in order to keep the downward closure property. This makes the utilities of itemsets be estimated too large， resulting in bad pruning effect and low mining efficiency. To solve this problem， the concept of the index utility was proposed. On this basis， the two-level index was built and pruned， by which the pruning effect was strengthened and the efficiency of Top-k high utility itemset mining was enhanced. Moreover， the fast calculation of itemset utilities was supported by building the utility matrix. Therefore， the mining efficiency was further enhanced. The experiments on different types of datasets validate the effectiveness and the efficiency of the proposed method.

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Pre-record: a High-Efficiency Dynamic Process Migration Algorithm

SHAN Zhong-yuan， QIAO Jian-zhong， LIN Shu-kuan

2016, 37 (1): 29-33. DOI: 10.12068/j.issn.1005-3026.2016.01.007

Abstract ( 678 )

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Post-copy algorithm needs process to resume running while address space is incomplete. Due to the frequently occurring page faults， it would cause process executing intermittently which may significantly reduce migration efficiency. So， a new migration algorithm named as Pre-record was proposed to solve this problem. Based on the proposed algorithm， process execution on host node would be prolonged and the visited memory pages would be recorded. Host node will migrate these recorded pages preferentially， and then continue to push the rest of the address space. This can guarantee that the needed memory pages could have been acquired at the beginning phase of process resume running in which phase page faults have the highest frequency. Analysis and simulation experiments show that Pre-record algorithm can reduce the occurrence rate of page faults effectively and improve the efficiency of process migration， and it also has the advantages of short freeze time and less residual dependence.

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Effects of Aging Time on Microstructure and Properties of Wrought Al-Si Alloy

LIU Fang， YU Fu-xiao， ZHAO Da-zhi， ZUO Liang

2016, 37 (1): 34-38. DOI: 10.12068/j.issn.1005-3026.2016.01.008

Abstract ( 755 )

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The effects of aging time on microstructure and properties of as-solutioned wrought Al-12.7Si-0.7Mg alloy artificial aged at 180℃ for different time were investigated. The results showed that the age hardening curves of different as-solutioned state alloys present single or twin peaks aging strengthening characteristics. Age hardening curve of wrought Al-Si alloy aged at 180℃ after solutioning at 520℃ for 30min exhibits obvious age hardening “twin peaks”， and the second age hardening peak is higher than the first one. The single and twin peaks age hardening phenomenon of alloy is closely related to the type， size， and the precipitation sequence of precipitates. The obvious interval during meta-stable phase transformation of alloy is the main reason for twin peaks aging hardening.

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Microstructure and Mechanical Properties of Welding Joints of Fe-6.5%Si Alloy Hot Bands

LIU Jin-long， SHA Yu-hui， WEN Xiu-xiu， ZUO Liang

2016, 37 (1): 39-43. DOI: 10.12068/j.issn.1005-3026.2016.01.009

Abstract ( 656 )

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To solve the problem that welding joint is easy to crack in hot bands of Fe-6.5%Si alloy， the effect of argon arc welding process on the microstructure and mechanical properties of joints was investigated. The results showed that TIG welding without filler wire is not suitable for the welding of Fe-6.5%Si alloy hot bands because it produces a large number of cracks in the weld. While MIG welding using the electrodes made of industrial pure iron successfully connects the hot bands. The weld is continuous in the surface， the fish-scale pattern is uniform and no micro-cracks are in the weld. The optimization of microstructure and plasticity can be attributed to the dilution of silicon concentration in the weld zone. After the optimization of welding process， the tensile elongation and the ultimate tensile strength of the joint are 5.5% and 280MPa， respectively， which can meet the requirement of warm rolling process of Fe-6.5%Si alloy.

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Precipitation Behavior of Ultra-pure Ferritic Stainless Steel During Hot Deformation

GAO Fei， LIU Zhen-yu， YU Fu-xiao

2016, 37 (1): 44-48. DOI: 10.12068/j.issn.1005-3026.2016.01.010

Abstract ( 678 )

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The precipitation behavior of an ultra-pure medium-chromium ferritic stainless steel with addition of Ti and V during hot deformation was studied using a thermomechanical simulator and pilot rolling mill. The characteristic of precipitates was investigated using thermodynamic calculation and transmission electron microscopy. The results showed that TiC is primary precipitate formed during hot deformation， in agreement with the thermodynamic calculation. The characteristic of these precipitates is closely dependent on deformation temperature. The TiC formed during hot deformation at relatively low temperature is finer in size and denser in dispersion than that at high temperature. This can be explained by a combination of the slower diffusion rate associated with the lower deformation temperature which is unfavorable to precipitate growth， and increasing lattice defects due to lower deformation temperature which can generate more nucleation sites for the strain-induced precipitates. This precipitation behavior during hot deformation is confirmed by the pilot rolling experiments.

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Exfoliation Mechanism of Galvannealed Coating by Three Point Bend Test

DENG Yong-gang， DI Hong-shuang， HU Mei-yuan， ZHANG Jie-cen

2016, 37 (1): 49-53. DOI: 10.12068/j.issn.1005-3026.2016.01.011

Abstract ( 502 )

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The open， stretch and exfoliation of cracks in the galvannealed (GA) steel sheets under different stress states (tensile or compressive stress) were studied by three point bend test， EPMA， SEM and OM. The results showed that the cracks are generated in the δ and Γ phase during the cooling process after alloying annealed. The open， stretch and exfoliation mechanism of cracks in the coating are different for the tensile and compressive stress. When the coating subjects to tensile stress， the cracks propagate perpendicularly to coating plane， then the cracks reach and propagate along the Γ-αFe interface， while contact to the second crack， the coating exfoliates. In the coating subjected to compressive stress， the cracks are generated in the δ phase and propagated at an angle inclined to coating plane in the δ phase. Then， fracture occurs within δ phase or along the Γ-αFe interface. Furthermore， the exfoliation of the coating occurs more easily in compressive deformation than in tensile deformation.

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Effect of Mold Oscillation on Initial Cracks Formation of Continuous Casting Slabs

MENG Xiang-ning， LIN Ren-gan， YANG Jie， ZHU Miao-yong

2016, 37 (1): 54-58. DOI: 10.12068/j.issn.1005-3026.2016.01.012

Abstract ( 547 )

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The previous researches on the stress state of initial solidifying shell in oscillation mold and the detailed reasons to clarify the crack formation process were summarized. The mechanical stress caused by mold oscillation has a dominant contribution to the initial cracks formation as a nonnegligible factor， so a new model was proposed to shed light on the influence of mold oscillation on the initial cracks formation. The stress states of the shell were analyzed for an oscillation cycle. The results showed that the mold oscillation plays an important role on the cracks formation because the maximum bending stress in initial solidifying shell can reach to 148.4kPa and the critical fracture strength of the shell is only 119.1kPa. The initial crack will form when the oscillation velocity is higher than 1.61m·min^-1， which is located in the region of 2.15~5.4mm under the free surface of steel in the mold because the critical fracture strength at a certain temperature is exceeded.

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Phase Transformation and Leaching Property of Low-Lime Calcium Aluminate Clinker

ZHANG Di， YU Hai-yan， PAN Xiao-lin， ZHAI Yu-chun

2016, 37 (1): 59-63. DOI: 10.12068/j.issn.1005-3026.2016.01.013

Abstract ( 623 )

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The melting temperature， mineral phases， pulverization and alumina-leaching properties of clinkers were studied by using analytical reagent CaCO₃， Al₂O₃ and SiO₂ as raw materials. The molar ratio of CaO to Al₂O₃ is 1.0 and the mass ratio of Al₂O₃ to SiO₂ is 3.0. The results showed that the melting temperature of the sample is 1392℃. The clinker sintered at 1350℃ is composed of CaAl₂O₄， Ca₁₂Al₁₄O₃₃ and γ-Ca₂SiO₄， which has good pulverization property and alumina leaching rate of 93.37%. The materials melt locally and turn into heterogeneous phases at 1400℃， which blocks the elemental diffusion， results in non-homogeneous phases， and inhibits the conversion of β-Ca₂SiO₄ to γ-Ca₂SiO₄. The formation of Ca₂Al₂SiO₇ and deterioration of pulverization property sintered at 1400℃ are the main reasons for the low alumina leaching rate of 74.50%. The clinker sintered at 1450℃ melts completely， which improves the pulverization property and the alumina leaching property of clinker.

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Study on the Microstructure of Stamp Charging Coke

GAO Bing， ZHANG Jian-liang， KONG De-wen， ZUO Hai-bin

2016, 37 (1): 64-69. DOI: 10.12068/j.issn.1005-3026.2016.01.014

Abstract ( 612 )

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Applying the stamp charging technology， the effect of high-bulk-density coal blending on the microstructure of coke was investigated. The results showed that the pore structure of coke was greatly influenced by the stamp charging technology. The pore structure of cokes was examined by using N₂ adsorption technology. All 9 kinds of stamp charging coke contained mainly medium and small pores whose sizes were less than 10nm. The mean pore diameter was small and the specific surface area distributed widely. However， 3 kinds of top charging coke all contained a certain amount of medium pores of 20~ 50nm. The mean pore diameter was larger and the specific surface area was smaller. Compared with the top charging coke， the total porosity， apparent porosity and apparent porosity ratio of stamp charging coke were almost all smaller. The true density was nearly the same and the apparent density was lower obviously. So， it is easy to distinguish the top charging coke and stamp charging coke according to the apparent density. The optical textures of coke depend mainly on the quality of coal blends， while there is no significant difference between top charging coke and stamp charging coke.

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Experimental Study of the Induced Caving Method in the Shuangyashan Iron Mine

MA Jiao-yang， REN Feng-yu， HE Rong-xing， YAN Xi-ming

2016, 37 (1): 69-73. DOI: 10.12068/j.issn.1005-3026.2016.01.015

Abstract ( 651 )

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The cutting roadway， the broached groove of oblique blasthole and both ends retreat mining of the induced caving method was proposed due to difficult stope preparation and cutting engineering， poor stope safety conditions and high loss and dilution of the steeply inclined and fractured medium thick orebody in Shuangyashan iron mine. The suitable parameters to induce orebody caving were given. The caving process and the lumpiness of caving block were analyzed and the loss rate and dilution rate of caving ore were estimated based on the No.S5 stope in Shuangyashan iron mine. According to results of the regular shift recordings， the recovery rate was higher and the degree of the caving block was good in early recovery period， which was consistent with previous analyses. The rock mixing rate increased along with cycle changes after complete caving， and the phenomenon was associated with the position of the drilling of roadway and the lumpiness of blasting blocks. The recovery indexes of this method are good and the mining problems of the steeply inclined and fractured medium thick orebody can be effectively solved.

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Stability Evaluation of Stope Based on Mathews Graph Method

ZHAO Yong， YANG Tian-hong， WANG Xin-rong， HU Gao-jian

2016, 37 (1): 74-78. DOI: 10.12068/j.issn.1005-3026.2016.01.016

Abstract ( 970 )

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There are eighty unprocessed mined-out areas in Hongling lead-zinc ore for years of mining.In order to evaluate the stability of the goafs， several kinds of indexes representing the engineering quality of rock mass in mines were acquired by the survey of engineering geology and the ore-bearing rock mechanics experiments. According to the acquired ore and rock mechanics index， the stability number and radius of hydraulic in testing goaf were calculated using the Mathews stability graph method.And stability and probability of the testing goaf were evaluated by rendering synthetic map including the isoprobability contours and the Mathews stability graph. The testing goaf was simulated with FLAC^3D， and the results agreed well with the results by using the Mathews stability graph method. The parameters for unstable goaf were optimized， and some supporting measures for the unstable goaf were proposed. This method can be used to evaluate all goafs in Hongling ore and provide reference for the similar mines.

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Optimizing the Whole Boundary of Open Pit Mining Areas with Restrictions

XU Xiao-chuan， GU Xiao-wei， WANG Qing， LIU Jian-ping

2016, 37 (1): 79-84. DOI: 10.12068/j.issn.1005-3026.2016.01.017

Abstract ( 626 )

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Based on the theory of floating cone exclusive method， the ultimate boundary of two open pits in different producing conditions was optimized together by Smart Miner software. In view of the technical and economic parameters being different in open pits and the optimization results being sensitive to these parameters， the software incorporated some functions to indentify the partitions of mining objects and optimized the boundary by the corresponding parameters in each partition. Meanwhile， the software incorporated the function of optimizing boundary in any constraint ranges for the mining range being restricted by the surface structures. Taking Sijiaying open pit as an example， the ultimate boundary was optimized with restrictions and non-restrictions according to the parameters in different partitions. The results showed that the surface structures which caused 0.1 billion ore loss were a strong constraint to the optimum boundary. The 0.1 billion ores formed hanging wall ores from -202m level. If the hanging wall ores were still mined opening， the cost of moving surface structures must be less than 0.34 billion.

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Method of Engineering Volume Monitoring and Calculation for Open-Pit Mine from UAV Images

XU Zhi-hua， WU Li-xin○， CHEN Shao-jie， WANG Zhi

2016, 37 (1): 84-88. DOI: 10.12068/j.issn.1005-3026.2016.01.018

Abstract ( 783 )

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The image sequences from an unmanned aerial vehicle (UAV) are used to calculate the engineering volume (overburden amount， stacking amount， etc.) of open-pit mine. Firstly， two sets of video frames or optical images of the open-pit mine are collected with a time interval using a portable digital camera installed on an octocopter. Next， two groups of the point clouds are automatically generated by implementing structure from motion (SfM) and patch-based multi-view stereo (PMVS) algorithms. And then， the two point clouds are fine registered with a constant region-based registration method. Finally， the engineering volume is computed with a differential method for digital terrain model triangulated irregular network (DTM-TIN). It shows that the relative error of the point cloud model is lower than ±1% in the experiment for change detection of a stacking stockpile with UAV images. Moreover， the accuracy for monitoring the volume change is up to 92%， which is comparable to that of a terrestrial laser scanning.

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Identification and Bioleaching Capacity of an Acidithiobacillus Ferrooxidan

LU Tao， WEI De-zhou， ZHANG Rui-yang， ZHUO Jian-ying

2016, 37 (1): 89-93. DOI: 10.12068/j.issn.1005-3026.2016.01.019

Abstract ( 665 )

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A bioleaching bacterium was isolated from an acidic mine drainage of Jiama polymetallic mine in Tibet and was named as XZ. The strain XZ， with round ends， is gram-negative and short-rod shaped in 1～1.5μm×0.5μm. Ferrous iron and elemental sulfur could be oxidized by strain XZ. The optimum growth pH is 2.0 and the optimum growth temperature is 30℃. It was identified as Acidithiobacillus ferrooxidans by means of growth characteristic research and 16S rRNA sequencing. The strain XZ was used to leach a poor copper hornstone ore took from Tibet.Shaking flask leaching tests were carried out with inoculation size of 10%(volume fraction)， pulp mass fraction of 10% ，ore particle size of -45μm accounting for 100%， leaching temperature of 30℃ and shaking intensity of 160r/min. The results show that leaching rate of copper can reach 72.15% after 15 days.

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Ecological Security Effect Evaluation of Mine Based on Fuzzy Analytical Hierarchy Process and Variable Fuzzy Sets

XUE Xi-long， WANG Xin-min， HU Yong， YANG Li

2016, 37 (1): 94-99. DOI: 10.12068/j.issn.1005-3026.2016.01.020

Abstract ( 617 )

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In order to quantitatively evaluate ecological security current status in metal mines， the evaluation index system and evaluation grading criterions of ecological security effect in metal mines were created. Weights of evaluation subsystem and secondary indexes were obtained by the fuzzy analytical hierarchy process(FAHP). An evaluation integrated model was built for ecological security effect in metal mines on the basis of FAHP and variable fuzzy sets. The model was applied to evaluate ecological security effect for a large copper mine in Anhui province. Through the calculation of the model， the ecological security effect grade of production effect， natural endowment effect and socioeconomic effect was classified as class Ⅱ; the environmental effect subsystem was classified as class Ⅲ. The overall evaluation of the copper mine was classified as class Ⅱ. The results show that the model is reliable and flexible and its results are consistent with the actual situations and those of other models.

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Physicochemical Characteristics of Corn Cob Biomass Ash

YAO Xi-wen， XU Kai-li， WANG Wen-jing， ZHANG Xiu-min

2016, 37 (1): 100-104. DOI: 10.12068/j.issn.1005-3026.2016.01.021

Abstract ( 853 )

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The physicochemical characteristics of corn cob ash obtained at different ashing temperatures(600℃ and 815℃) were studied with X-ray fluorescence spectrometry， X-ray diffraction， scanning electronic microscopy and grading analysis. Muffle furnace burning experiment was adopted to study the influence of ashing temperature and holding time on ash content. The ash composition and morphology of the fly ash samples collected from biomass gasification station were analyzed by using scanning electron microscopy(SEM) and energy disperse X-ray microanalysis(EDX). The results indicated that ashing temperature has a remarkable effect on the ash granularity， content， composition， morphology and phase composition， but has no obvious effects on the fouling and slagging characteristics. The main component elements of ash are potassium and chlorine， which means that the major existent form of potassium is potassium chloride in the pyrolysis and gasification process of corn cob. The morphology of ash surface is in different shapes.Flocculent large particles were formed at the ashing temperature of 600℃， while the ash surface happens to soften and fuse， and the flocculent particles decreases at 815℃. Above research results can provide guidance not only for the purification of gas obtained from the thermal chemical conversion of biomass fuel， but also for the comprehensive utilization of biomass ash.

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Community Structure of Anode Biofilm by High-Throughput Sequencing Technology

WANG You-zhao，ZHU Tong，XIE Yuan-hua，LI Xian-jin

2016, 37 (1): 105-109. DOI: 10.12068/j.issn.1005-3026.2016.01.022

Abstract ( 676 )

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Microbial community structure of anode biofilm was analyzed using high-throughput sequencing technology. The results show that the technology can obtain community structure information from electrochemistry biofilm efficiently， and the exoelectrogentic modal bacteria Geobacter category is predominant in biological membrane， its quantity ratio reaches 30%；Thermovirga，Thauera and Syntrophorhabdus are also found in anode biofilm. However， through comparison of biofilm before and after electrochemical activity was lost， Geobacter still dominated in biofilm after the biofilm lost electrochemical activity，while Actinomycetes’ proportion increased significantly， its quantity was much higher than that of the normal 0.5%. So Actinomycetes may be one of the factors which inhibit the electrochemical activity of the biofilm.

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Improving Collection Efficiency of the High Specific Resistance Dust by the Counter-Current Charged Dual-Zone ESP

HAO Wen-ge ， ZHANG Cong ， YANG Yan-yun， HUANG Wen-jie

2016, 37 (1): 109-113. DOI: 10.12068/j.issn.1005-3026.2016.01.023

Abstract ( 513 )

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In order to improve the purification effect of ESP on high resistivity dust in flue gas， U-I characteristics and collection efficiency of cleaning normal or high resistivity dust gas were measured in the three electrostatic precipitators test model such as ordinary single district， the conventional dual-zone and dual-zone counter-current charged . In the process of cleaning high resistivity dust gas by ordinary single district and the conventional dual-zone ESP， when the voltage rises to 50kV ， dust collection electric field occurs back corona and the collection efficiency begins to decline. While the trends of U-I characteristic curve have no significant differences when dual-zone counter-current charged ESP cleaning gas containing the high specific resistance dust and the normal specific resistance dust， and the collection efficiency and voltage show the same trends. The research results confirm that the new ESP can avoid anti-corona and improve the effects of cleaning dust effectively for the purification of flue gas containing a high resistivity dust.

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The Ignition Characteristics of Diesel in Fire Flashover Experiment in Confined Space

ZHANG Pei-hong， YU Yan-qiu， ZHAO Peng-cheng， TANG Xiao-ying

2016, 37 (1): 114-117. DOI: 10.12068/j.issn.1005-3026.2016.01.024

Abstract ( 660 )

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Fire flashover tests were conducted with different diameters of ethanol under different ventilation conditions by using ethanol as the main fuel and diesel as the second fuel. The average temperature in the upper layer of the hot smoke， the radiation heat flux at the floor and the oxygen concentration were measured to analyze the critical ignition conditions of the diesel. The results illustrated that the diesel can be ignited when the average temperate in the upper layer of the hot smoke is over 364℃， the radiation heat flux at the floor is higher than 4.38kW/m² and the oxygen concentration reaches 20.4% under the experiment state. If the oxygen concentration is reduced to 18.5%， the diesel can be ignited when the critical average temperate in the upper layer of the hot smoke is over 390℃and the radiant heat flux at the floor is higher than 6.65kW/m². It is concluded that in confined space， the critical parameters for the ignition of disel， i.e. the oxygen concentration， the average temperature in the upper layer of the hot smoke and the radiant heat flux at the floor are mutually interinhibitive.

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Axial Compression Performance of Splicing Concrete-Filled GFRP Tubular Composite Component

ZHANG Ni，WANG Lian-guang， CHEN Bai-ling

2016, 37 (1): 118-122. DOI: 10.12068/j.issn.1005-3026.2016.01.025

Abstract ( 477 )

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The splicing concrete-filled GFRP tube composite members is a new kind of composite member， which is composed of two independent GFRP tubes connected by connectors with poured concrete inside. The mechanical behavior and failure modes of splicing and continuous concrete-filled GFRP tubular composite member connected by steel bars， steel plates and steel tube under axial load were studied. The results indicated that white stripes appeare on the surface of GFRP tube when the load reaches about (30%~40%)P_u (limit load)， and the confinement effect of GFRP tube are motivated when the load reaches (60%~70%)P_u. The failure of splicing specimens occurrs near the end of connectors instead of the splicing joint. However， the failure of the continuous specimen occurrs in the middle of the specimen. Results show that the influence of the three connecting ways can ensure the normal work of splicing concrete-filled structures.

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Experimental Study on the Mechanical Properties of Frozen Tailings by Uniaxial Compression Tests

WEI Zuo-an ，YANG Yong-hao， XU Jia-jun，CHEN Yu-long

2016, 37 (1): 123-127. DOI: 10.12068/j.issn.1005-3026.2016.01.026

Abstract ( 613 )

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The frozen of tailings can affect the stability of the tailing dam. The uniaxial compression tests were carried out to study the mechanical characteristics of artificial frozen tailing and its four influence factors. There are three types of failure modes for frozen tailing specimen， i.e. shear failure in oblique section， tensile failure in radial direction and composite failure mode. The stress-strain curve of the frozen tailings samples can be divided into four stages: the axial compressive tests as initial stain softening stage， linear strain hardening stage， nonlinear strain hardening stage and softening stage. In the four factors， the uniaxial compressive strength is logarithmically related to the average particle size， exponentially related to the dry density ，linearly related to the moisture and parabolically related to the loading rate. The deformation modulus of frozen tailings is logarithmically related to the average particle size， exponentially related to the dry density and loading rate， and parabolically related to the water content.

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Design Method of Dynamic Parameters for a Dual-Mass Vibrating System

HE Bin， ZHAO Chun-yu， HAN Yan-long， WEN Bang-chun

2016, 37 (1): 127-132. DOI: 10.12068/j.issn.1005-3026.2016.01.027

Abstract ( 560 )

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The relations between force transmission coefficient of the system to its foundation，the characteristic amplitude of the working mass and the system dynamics parameters were deduced by theoretically analyzing a vibrating system with dual masses. Coefficient of vibrating material， critical frequency ratio and its difference， and the increase in characteristic amplitude were defined. Through numeric analysis， the domain where the force transmission coefficient was less than 10% was determined. The conclusions show that with isolation frequency ratio increasing， force transmission coefficient reduces and characteristic amplitude increases. And characteristic amplitude does not increase with adding of vibrating material mass when the mass ratio is more than 0.57. The less mass ratio of the working body is， the larger the possibility of domain with the low force transmission coefficient and large characteristic amplitude is realized. The method to determine the system dynamics parameters is proposed to ensure the vibration isolation effect， the vibrating material of maximum coefficient， the characteristic amplitude and the increase in characteristic amplitude.

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Optimization of Grinding Parameters for Drill Points with a Biglide Parallel Machine Based on Genetic Algorithm

KIM Myong-il， ZOU Ping， WU Hao

2016, 37 (1): 133-137. DOI: 10.12068/j.issn.1005-3026.2016.01.028

Abstract ( 545 )

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In view of helical drill point grinding， the theoretical and experimental bases for grinding the required geometrical parameters of helical drill points are presented in this paper based on the optimization of biglide parallel machine grinding parameters. A method of grinding the involute helical surface based on the biglide parallel machine is introduced， and then the mathematical model is derived for the helical drill flank. Moreover， the relationship between the geometric parameters and grinding parameters is analyzed， and the optimal grinding parameters are acquired based on genetic algorithm. The results showed that the optimized grinding parameters improve the grinding precision with the experiment on the biglide parallel machine， and the biglide parallel machine can satisfy clients’ demands of drill grinding.

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Disjunctive Graph-Based Scheduling Algorithm for Job Shop with Material Handling

ZHOU Bing-hai， ZHOU Shu-mei， ZHAO Meng

2016, 37 (1): 138-142. DOI: 10.12068/j.issn.1005-3026.2016.01.029

Abstract ( 1245 )

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Take the scheduling problems of the Job Shop with material handling equipment into consideration， we established the non-linear programming model and modified disjunctive graph model. Afterwards， a two-stage structural heuristic algorithm was constructed to minimize the makespan. In the first stage， a hierarchical heuristic algorithm was constructed by dividing the disjunctive graph into sub-graphs of scheduling problems for the machines and handling equipment， respectively. The sub-graphs of scheduling problems for the machines in the upper level were solved based on a branch method， while for the handling equipment in the second level were according to the upper level results. In the second stage， a heuristic algorithm based on the block theory was presented to optimize the scheduling solutions. Finally， simulation experiments were designed and indicated that the proposed algorithm is valid and feasible.

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Design and High-Speed Characteristics of Automotive Hybrid Chain System

CHENG Ya-bing，WANG Yang，QI Hong-gang， FU Zhen-ming

2016, 37 (1): 143-147. DOI: 10.12068/j.issn.1005-3026.2016.01.030

Abstract ( 628 )

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The theoretic meshing of hybrid Hy-Vo silent chain system was designed. Based on design projects， the parameters were calculated and the transmission system was arranged. The wear test was performed to gain the wear curve of the novel Hy-Vo silent chain and the microscopic scanning of the wearing terrain. The results indicated that the special-shaped pin of the Hy-Vo chain can bear the load with rolling friction alternatively， and the bearing surface pressure of Hy-Vo chain is lower， resulting in a higher wear resistent property. The wear mechanism synthesizes fatigue wear， abrasive wear and fretting wear. The service life of automotive hybrid Hy-Vo chain system can be improved by enhancing the precision of fabrication and assembly.

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Decision Model for Transmission and Control of Financial Distress Under the Centralized Supply Chain

LI Li-jun， LIU Jie， YUAN Zhi-zhu

2016, 37 (1): 148-152. DOI: 10.12068/j.issn.1005-3026.2016.01.031

Abstract ( 528 )

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Supply chain has increasingly become a main mode of competition in the market. Once a retailer in the supply chain falls into financial distress， it will be passed on to others by quantity of goods， which may lead to a distress of the whole supply chain. In a two-stage supply chain with a single manufacturer and retailer， based on the business effort level and effort cost， the process of how financial distress goes from the retailer to the manufacturer was described and the manufacturer’s decision-making under the centralized financial distress was explored under various contexts. The results showed that in the case of lighter distress ， both the manufacturer and the retailer tend to adopt the centralized decision-making， and in a severe predicament， the manufacturer should change decisions or cancel strategic partnership to prevent the transmission of financial distress. Finally， an example is given to illustrate the specific application of the decision model and verify its feasibility.

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