Journal of Northeastern University(Natural Science)

3D Sensing Model Based Optimal Space-Coverage Research for WMSNs

JIA Zi-xi， WU Cheng-dong， ZHANG Yun-zhou， WANG Qing-jia

2015, 36 (12): 1673-1677. DOI: 10.12068/j.issn.1005-3026.2015.12.001

Abstract ( 646 )

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The majority of the researches about the coverage problem of wireless multi-media sensor networks(WMSNs) are based on 2D sensing model. For video nodes， 2D sensing model cannot describe their sensing range precisely， and the space above the monitoring horizon is generally omitted. Thus， the concept of space coverage was proposed， and a new 3D sensing model was defined. By separating the two factors pitch angles and deflection angles which can seriously influence the space coverage， the Particle Swarm Optimization (PSO) was employed for optimizing the 1-space coverage. By considering the requirements of practical applications， the concept of efficient space coverage was proposed here， which can guarantee the efficient video collection of monitoring targets. At last， the degree of space coverage is significantly improved by means of simulation， which proves the proposed optimization efficient.

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New Observer-based Fuzzy H_∞Control Approach for Steam Valve Opening of Multi-machine Power Systems

LIU Xin-rui， SUN Qiu-ye， XIE Zhi-yuan， HOU Xin-ming

2015, 36 (12): 1678-1682. DOI: 10.12068/j.issn.1005-3026.2015.12.002

Abstract ( 601 )

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The observer-based fuzzy H_∞ controller design problem was considered for steam valve opening of multi-machine power systems which is consisting of turbo-generators. Firstly， T-S fuzzy model was used to establish the model for multi-machine power systems. Because sometimes the measurable state variables of actual power systems may not be used as the premise variables of the fuzzy rules， the observer-based conditions were derived to guarantee the H_∞ performance. However， the conditions are not based on the linear matrix inequalities (LMIs)， which can only be solved by a two-step method. Then the LMIs-based conditions by only one step were proposed， in which the conservativeness of the conditions was reduced. Finally， the T-S fuzzy model was established for the steam valve opening of two-machine infinite bus power systems with local linearization method， and effectiveness of the proposed controller design was verified by the simulation results.

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A Hybrid Composite Service Execution Mechanism Based on the Characteristics of the Execution Environment

YANG Lei， DAI Yu， ZHANG Bin

2015, 36 (12): 1682-1686. DOI: 10.12068/j.issn.1005-3026.2015.12.003

Abstract ( 512 )

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A hybrid execution mechanism for composite service was researched. The interaction protocol between the services was established， and the characteristic model of the execution environment was presented. In addition， the rules for dynamically selecting the execution schema were proposed. The mechanism was a combination of execution schema of the centralized control-flow and data-flow as well as the execution schema of the centralized control-flow and decentralized data-flow， which could dynamically select the execution schema according to the feature of the business and the execution environment of the composite service. And then the message with large data amount could be transferred between the services without being redirected by the central node. The experimental results showed that the dynamic selection of the execution schemas could ensure the execution efficiency of the composite service.

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Image Reconstruction Method Based on Compressed Sensing for Magnetic Induction Tomography

WANG Jing-wen， WANG Xu

2015, 36 (12): 1687-1690. DOI: 10.12068/j.issn.1005-3026.2015.12.004

Abstract ( 653 )

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To improve image reconstruction quality of magnetic induction tomography (MIT)， a new MIT image reconstruction method based on compressed sensing was put forward. Here the voltage collection process of MIT system was regarded as linear measurement process of compressed sensing， the measurement matrix was designed by zero expansion of the sensitivity matrix and its row vectors random reconstruction， and the measurement voltage vector expanded by the same way was regarded as measurement signals of compressed sensing. The original signal was recovered by signal reconstruction method of compressed sensing. Finally， the simulation experiments were performed. The experimental results indicated that the average image reconstruction error and the average correlation coefficient obtained by the method are better than corresponding indicators obtained by the traditional reconstruction image algorithm. So it is a kind of MIT image reconstruction method with high accuracy.

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Research on Routing Strategy Based on Edge Weight and Node Load

XU Jiu-qiang， LI He-qun， WANG Jin-fa， ZHAO Hai

2015, 36 (12): 1691-1695. DOI: 10.12068/j.issn.1005-3026.2015.12.005

Abstract ( 591 )

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With the promotion of the practical status in human life， the study of routing strategy in packer switched network(PSN)， such as traffic networks and airline networks， has attracted more attention. In this paper， congestion problems in PSN were analyzed by complex networks methods and solutions were given respectively from either static property or dynamic characteristics. Then a new routing strategy was put forward， in which path was chosen according to the edge weight and node load. Compared with the existing strategies， the new strategy can alleviate congestion， improve network efficiency， and has certain practical value.

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An Inter-Class Integration Test Order Generation Method Based on Complex Networks

ZHAO Yu-li， WANG Ying， YU Hai， ZHU Zhi-liang

2015, 36 (12): 1696-1700. DOI: 10.12068/j.issn.1005-3026.2015.12.006

Abstract ( 615 )

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Inter-class integration test is a critical part of the object-oriented software testing. Representing a class by a node in a complex network， two classes are connected only if there exist an invoke relationship between them. Then， a complex network model representing object-oriented software could be constructed. According to the characteristics of the complex network structure， the influence and complexity of each class node was analyzed. Further， an approach for measure the significant nodes in the software network were provided. Moreover， the idea that error should be found as soon as possible was applied to the inter-class integration test order， an inter-class integration test order generation method was proposed， in which the test priority of the significant nodes and the lower test stub complexity were ensured. Simulation result on the open source software DNS 1.2.0 indicated the effectiveness of the proposed method.

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Precipitation Behaviors of Nanometer-sized Carbides in a Niobium-Titanium Contained Low-Carbon Steel

LI Xiao-lin， WANG Zhao-dong

2015, 36 (12): 1701-1705. DOI: 10.12068/j.issn.1005-3026.2015.12.007

Abstract ( 574 )

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The microstructure， mechanical properties and precipitation behaviors in a low carbon Nb-Ti micro-alloyed steel were investigated using the dilatometer， Vickers-hardness tester and transmission electron microscope. The results showed that the microstructure of the experimental steel treated by an isothermal quenching process under different temperatures all mainly consisted of ferrite and martensite phases. The volume fraction of ferrite phase increased with the decrease of the isothermal temperature. Both of the interphase precipitation and supersaturated precipitation of carbides appeared in the samples treated by the isothermal quenching process. Along with the decrease of isothermal temperature， the precipitation form gradually changed from the interphase precipitation to supersaturated precipitation. Furthermore， the interphase-precipitated carbides had a NaCl-type crystal structure with a lattice parameter of 0.432nm and obeyed the Baker-Nutting (B-N) orientation relationship with respect to the ferrite matrix which confirmed by HRTEM. The Vickers-hardness of the ferrite increased with the decrease of the isothermal temperature.

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Research and Development of the Test Platform for Large Air Flotation Type Annealing Furnaces

HOU Shuai， WANG Xiao， HUA Fu-an， WANG Guo-dong

2015, 36 (12): 1706-1709. DOI: 10.12068/j.issn.1005-3026.2015.12.008

Abstract ( 663 )

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In order to study the operation mechanism of industrial air flotation annealing furnace， the mechanical structure and control system are developed and the flotation height of web is established using the heat treatment zone as a subject. According to the operation process， the experimental air flotation platform can stabilize one series aluminum strips with the thickness of 0.3~2mm to the float heights between 0~200mm. The hybrid flotation height model can predict the flotation height of the strips precisely， whose accuracy is ±3mm. The structure and running process of the developed air flotation platform are similar to those of present industrialized air flotation furnaces structure. The research provides good theoretical guidance to industrialize air flotation oven.

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Analysis of Rolling Forces About Symmetric and Anti-Symmetric Parabola Dog-Bone Model in Vertical Rolling

ZHANG Dian-hua， LIU Yuan-ming， ZHAO De-wen， JIN Cheng-jun

2015, 36 (12): 1710-1714. DOI: 10.12068/j.issn.1005-3026.2015.12.009

Abstract ( 597 )

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To improve the quality of hot rolling products， the width precision of the hot rolling strip must be guaranteed. Vertical mill is usually installed in the roughing trains to control the width in actual production processing， but the cross section of the strip formed as a dog-bone shape after vertical rolling. The symmetric and anti-symmetric parabola dog-bone function model and kinematically admissible velocity field in the vertical rolling are firstly proposed in present paper. Using the first variation principle of rigid-plastic material， analytical solutions of the total power functional and rolling force for the vertical rolling are obtained using variable upper limit integration. The error of the rolling force obtained above compared with that of FEM simulation result is within 3%， while is less than 6.3% compared with that obtained by Yun’s model. The precision can satisfy the requirement of production control using this anti-symmetric parabola model to predict the rolling force in a strip rolling plant.

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Optimization of the Rolling Force Self-learning for Specifications Changing in the Hot Strip Rolling

MA Geng-sheng， PENG Wen， DI Hong-shuang， ZHANG Dian-hua

2015, 36 (12): 1715-1718. DOI: 10.12068/j.issn.1005-3026.2015.12.010

Abstract ( 594 )

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In the hot strip rolling process， the prediction precision of the rolling force which is largely dependent on the rolling force self-learning directly affected the thickness precision of strips. In the view of the rolling force prediction precision decreased with the specifications changing， and through the analysis of the reasons for generating rolling force deviation， this paper introduced the concept of steel grade deformation resistance parabolic deviation curve， the equipment standers self-learning coefficient and equipment state effective coefficient to solve the problems. The practice application results showed that the relative error of the rolling force prediction for the first piece strip after changing specifications decreased by 4% compared with the conventional prediction method which satisfied the automatic thickness control system. The product quality of the strip was enhanced and good economic value was obtained， which indicated that the new prediction method was suitable for the industrial production promotion.

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Effects of Rare Earth La on Mechanical Properties of Casting AlSi10Cu0.2Mg0.2Mn and ZnAl12Cu1(Mg) Alloys

JANG Pok-nam ， LI Hyon-mo， WANG Zhao-wen

2015, 36 (12): 1719-1723. DOI: 10.12068/j.issn.1005-3026.2015.12.011

Abstract ( 624 )

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AlSi10Cu0.2Mg0.2Mn-xLa and ZnAl12Cu1(Mg)-xLa casting alloy were prepared by Al-La master alloy. The effect of La content on the microstructure， tensile strength， elongation and impact strength of these alloys were investigated. The results indicated that the crystalline grain of alloys could be refined by addition of La element and the size and shape of Si phase particle were also modified. Compared with the previous alloys， the mechanical properties of AlSi10Cu0.2Mg0.2Mn-xLa alloy and ZnAl12Cu1(Mg)-xLa alloy containing traces of La were relatively improved. When 0.15wt% of La was added in AlSi10Cu0.2Mg0.2Mn casting alloy， the elongation could increase to 2.7 times. The tensile strength and elongation of ZnAl12Cu1(Mg)-xLa containing 0.1wt% of La was increased to 1.3 and 3.2 times， respectively. The hardness of ZnAl12Cu1(Mg)-xLa containing 0.3wt% of La was increased to 1.8 times while ZnAl12Cu1(Mg)-xLa containing 0.15wt% of La exhibited the maximum impact strength. Comprehensively considering the mechanical properties of ZnAl12Cu1(Mg)-xLa casting alloy， the optimal addition content of La was controlled in the range of 0.1wt%~0.2wt%.

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Suitable Capacity of the Gasholder Based on a Dynamic Design Method in Steel Plants

YANG Jing-hui， CAI Jiu-ju， HUANG Jian， SUN Wen-qiang

2015, 36 (12): 1724-1728. DOI: 10.12068/j.issn.1005-3026.2015.12.012

Abstract ( 616 )

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In view of the problem of the gasholder design in steel plants， a dynamic design method was proposed to calculate the rational capacity of gasholders under the boiler fuel load regulating frequency matching condition through establishing mathematical model， which obtained good practice application. The case study showed that the determined volume of the gasholder by the application of this dynamic design method was greatly reduced compared with the previous one on the basis of ensuring stable production of byproduct gas system. The operating results were better than the current gasholder designed by the static methods and empirical design values in steel plants. Finally， the best fitting curve of the suitable capacities of gasholder corresponding to different regulating frequencies of boiler fuel load was given using this dynamic design method. The optimal allocation of surplus gas of the steel plants was solved and scientific guidance was provided for the optimization design of gasholder capacity in buffer users of the steel plants.

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Study on the Evaluation Method of Ladle Scheduling

FENG Kai， HE Dong-feng， XU An-jun， WANG Hong-bing

2015, 36 (12): 1728-1732. DOI: 10.12068/j.issn.1005-3026.2015.12.013

Abstract ( 558 )

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A new evaluation method of ladle scheduling status based on the production schedule and analysis on the interval stand-by time of ladle turnaround was proposed， due to the previous assessment on the basis of the number of turnaround ladle was difficult to reflect actual scheduling. Firstly， the influence of the production schedule on ladle running process was characterized by the fluctuation in the number of full package ladles. Then， the calculation method for the additional turnover package number and the offline ladle scheduling ratio was put forward through the analysis of ladle stand-by time， which was used to characterize ladle scheduling in different conditions， thus a comprehensive assessment method adopting practice production data was raised. Finally， the evaluation method was verified by the actual production data. The results show that the evaluation method can accurately evaluate the overall status of ladle scheduling and can provide guidance for the practice production process.

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Analysis on Relationship Between Degree of Damage and Energy Dissipation of Granite in SHPB Tests

YU Shui-sheng， LU Yu-bin， ZHU Wan-cheng， CAI Yong

2015, 36 (12): 1733-1737. DOI: 10.12068/j.issn.1005-3026.2015.12.014

Abstract ( 553 )

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A series of uniaxial compression tests under different strain rates on granite samples (74mm) were carried out using split Hopkinson pressure bars (SHPB)， to study the strain-rate effect and the relationship between the degree of damage and energy dissipation of granite. The test results show that the dynamic compression strength of granite has obvious strain rate effect. The energy dissipation per unit volume increases with the increase of strain rate， showing an approximate linear relationship. At the same time， the strain rate also increases with the increase of energy dissipation rate， showing nonlinear relationship. The degree of damage of granite samples has good consistency with the energy dissipation per unit volume， generally with one to one correspondence， but does not have one to one correspondence with the strain rate. There is no contradiction between the degree of damage of granite samples having inconsistence with the strain rate and strength enhancement with the strain rate.

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Comparative Study on the Variation Features of Infrared and Microwave Radiation in Deformation and Fracture Process of Rock

XU Zhong-yin， LIU Shan-jun， WU Li-xin

2015, 36 (12): 1738-1742. DOI: 10.12068/j.issn.1005-3026.2015.12.015

Abstract ( 483 )

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Multivariate information including infrared radiation， microwave radiation and strain were measured in uniaxial compressive experiments of rock. The result showed that infrared radiation and microwave radiation existed different staged variation features at various loading stages. The infrared radiation showed fluctuation in the initial loading stage， steady increase in elastic stage， rapid increase in the plastic stage and decrease in the fracture stage. The microwave radiation showed small decrease in the initial loading stage， steady increase in the elastic stage， decrease in the plastic stage and increase in the fracture stage. Two kinds of radiation information appeared different abnormal precursors of rock fracture， and the variation forms of precursors were just opposite. The combination of two detection technologies is favorable for detection of stress and disaster of rock.

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Simulation and Optimization of the SABC Comminution Circuit

KOU Jue， SUN Chun-bao， LIU Hong-jun， XU Tao

2015, 36 (12): 1743-1747. DOI: 10.12068/j.issn.1005-3026.2015.12.016

Abstract ( 579 )

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Realizing the existing issues that traditional empirical equations and Bond crushing work index are no longer fit for the reference basis of SABC circuit design and equipment sizing， an advanced simulation software JKSimMet was applied in this study to model the SABC comminution circuit of Wushan phase I copper-moly concentrator. The model was fitted and optimized based on the operation parameters. According to the simulation results the maximum throughput of Wushan SABC circuit is 850 t/h. The throughput of SABC circuit showed an increase of 26.7% after optimizing the operational parameters. Meanwhile， the comminution power consumption was decreased more than 2kW·h per ton， and the economic benefit was increased over 300 million yuan per year. Therefore， by using JKSimMet to simulate and optimize SABC circuit greatly increased the throughput and decreased the energy consumption. This result should shed some light on the domestic mining companies which are applying or plan to apply the SABC comminution circuit.

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Flotation Mechanism of New Dialkyl Dithiocarbonates Collector S-dodecyl O-isopropyl Dithiocarbonate (DIDTC)

TAN Xin， LU Liang， HE Fa-yu， YIN Wan-zhong

2015, 36 (12): 1748-1752. DOI: 10.12068/j.issn.1005-3026.2015.12.017

Abstract ( 682 )

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A positive dialkyl dithiocarbonates collector S-dodecyl O-isopropyl dithiocarbonate (DIDTC) was synthesized and used in the flotation separation of chalcopyrite from pyrite. The results of flotation test indicated that DIDTC collector had better selectivity than butyl xanthate. UV-vis spectra demonstrated that DIDTC showed more affinities to Cu²⁺ ions than to Fe³⁺ ions. FTIR spectra and adsorption test were executed to study the adsorption mechanism of DIDTC to chalcopyrite. The results elucidated that DIDTC might bond copper atoms of chalcopyrite surface with its sulfur and oxygen atoms in alkaline environments， and formed a multilayer at high concentration. In addition， the results were analyzed from the structure-activity of collectors by generalized perturbation theory and density functional calculation with GGA/PW91 as exchange correlation functional.

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Effect of Iron Ions on Denitrification Performance in Anammox Reactor

ZHANG Li， HU Xiao-min， JIANG Bin-hui， HUANG Yong-gang

2015, 36 (12): 1753-1756. DOI: 10.12068/j.issn.1005-3026.2015.12.018

Abstract ( 777 )

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The effect of different concentration of Fe²⁺ on the activity of anaerobic ammonium oxidation sludge was experimentally investigated by the addition of anammox sludge in stable operation at reactor. The experimental results show that: Fe²⁺ can promote cell synthesis of anaerobic ammonia oxidation bacteria and increase its matrix metabolism， through 210 days continuous operation. When the concentration of Fe²⁺ in the solution is 0.085mmol/L (4.76mg/L)， the ammonia nitrogen conversion rate remains at more than 90%. The heme content of anaerobic ammonia oxidation bacteria is increased by the addition of Fe²⁺. At this point， the heme C content reaches 0.143μmol/mg in the sample. It is 2.04 times heme content of anaerobic ammonia oxidation bacteria in comparison reactor at the same period. It is found that using SEM when the concentration of Fe²⁺ is 0.085mmol/L， the anaerobic ammonia oxidation bacteria form approaches to a steady state.

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Effect of Temperature on Phosphorus Distribution During Coal-based Reduction of Oolitic Iron Ore

LI Zhi-hang， HAN Yue-xin， SUN Yong-sheng， GAO Peng

2015, 36 (12): 1757-1760. DOI: 10.12068/j.issn.1005-3026.2015.12.019

Abstract ( 492 )

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As harmful element phosphorus concentrated in iron particles during reduction of oolitic iron ore， the reaction process of phosphorus migration was investigated. During the reaction process， reaction time is 80 min and reaction temperature are 1200， 1225， 1250 and 1275℃， respectively. Phosphorus distribution are analyzed in slag phase and metal phase and phosphorus migration route is also discussed. The results show below 1225℃ phosphorus content gradually increases from slag phase to phase interface， but decreases from phase interface to inner metal phase， and phosphorus content increases from phase interface to inner metal phase while temperature increases above 1250℃. Phosphorus migration route is also confirmed eventually. Firstly phosphorus exists in phosphate， phosphate reacts with carbon when the reaction begins， and then simple substance phosphorus is created and migrates into metal phase.

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Thermogravimetric-Mass Spectrometry Analysis and Pyrolysis Kinetic of Peanut Shell

YAO Xi-wen， XU Kai-li， YAN Fang， WANG Bei-bei

2015, 36 (12): 1761-1765. DOI: 10.12068/j.issn.1005-3026.2015.12.020

Abstract ( 627 )

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In the nitrogen atmosphere， simultaneous thermogravimetric-mass spectrometry(TG/MS) was used to study the pyrolysis behavior of peanut shell at different heating rates (5， 10 and 20℃/min)， and with the change of temperature and heating rates， the release rule of small molecule gas (CO₂， CH₄， H₂， CO) product was obtained by mass spectrometry analysis. Results showed that four stages appeared during pyrolysis process of peanut shell. Moreover， the greater the heating rate， the wider the weightlessness temperature range， and the steeper the maximum pyrolysis rate peak. The activation energy of peanut shell under different weight loss rates (0.2~0.8) ranged in 57.3~88.6kJ/mol by Flynn-Wall-Ozawa method. With Achar differential method and the Coats-Redfern integral method， it could be determined that pyrolysis process of peanut shell accords with the Jander equation after calculating 30 kinds of common mechanism function one by one， the reaction mechanism was three-dimensional uniformly spherical diffusion control. The reaction order was 2.

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Experimental Study on Basic Engineering Properties of Silt Improved by Lignin

ZHANG Tao ， CAI Guo-jun ， LIU Song-yu

2015, 36 (12): 1766-1770. DOI: 10.12068/j.issn.1005-3026.2015.12.021

Abstract ( 648 )

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The lignin， an industrial by-product， is utilized to improve the silt. A series of laboratory tests on moisture content， particle size distribution， compaction， unconfined compression strength and electrical resistivity are carried out to study the mechanical and physical properties of natural silt and lignin-improved silt. The pH value and electrical characteristics of improved soil are also investigated. Scanning electron microscopy (SEM) is used to analyze the variations of soils microstructure， and the stabilization mechanism of lignin-treated silt is preliminarily discussed. The results indicate that lignin can effectively improve the particle size distribution and reduce the plastic index of soil. As to improved silt， maximum dry density increases， the optimum moisture content decreases， while the change of dry density with moisture content is enhanced. The lignin-treated silt has greater strength performance than the natural silt in terms of unconfined compression strength and all the improved soils have a pH value lower than 10. Curing time and moisture content have a significant impact on unconfined compression strength， but little effect on pH value. The pores of soils are filled and particles are connected with cementing material， then a more stable soil structure was formed. It is shown that adding lignin can successfully improve the basic engineering properties of silt.

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Robust H_∞ Integrated Control Strategy of Vehicle and Seat Suspensions

ZHANG Li-ping， GUO Li-xin

2015, 36 (12): 1771-1775. DOI: 10.12068/j.issn.1005-3026.2015.12.022

Abstract ( 570 )

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Based on the integrated models of ‘vehicle-seat-people’， an integrated vehicle seat and suspension robust H_∞ integrated control strategy was proposed by using linear matrix inequalities (LMI) technique. An H_∞ state feedback controller of integrated vehicle seat and suspension was designed， with the PSD of vertical body acceleration chosen as the controlled outputs and the limits of dynamic suspension deflection， relative dynamic tire load， and integrated control force chosen as the constrained outputs. The MATLAB simulation was employed in the paper， and the simulation results confirm the feasibility and effectiveness. The analysis results provide a fundamental basis for the study of active control suspension system.

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Design of Bearing Crown Based on Coupling Dynamics of the Disc Cutter System

HUO Jun-zhou， WU Han-yang， ZHAO Kui-shan， LI Tao

2015, 36 (12): 1776-1779. DOI: 10.12068/j.issn.1005-3026.2015.12.023

Abstract ( 492 )

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To prevent the “edge effects” of the cutter bearing’s contact pressure distribution， it is particularly important to determine the appropriate modification parameters. Based on dynamic load obtained through simulation， cutter bearing’s load spectrum was generated by establishing the dynamics model of the disc cutter’s bending-axial-swing coupling system. And based on the maximum roller load， the model of cutter bearing was made by the Ansys in order to obtain the best parameters. The results show that compared with center cutter and face cutter， maximum load of edge cutter increases by 87% and 20%， respectively. The roller which is crowned of 0.029mm with contact ratio of 0.6 eliminates the stress concentration at roller-raceway contact edge， improves the contact stress distribution， with the average contact stress decreased by 17.26% and increases the contact fatigue life.

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Modeling Simulation of Full Frontal Impact and Scheme Choice for Some Vehicle Structure

TIAN Sheng， YANG Yang

2015, 36 (12): 1780-1784. DOI: 10.12068/j.issn.1005-3026.2015.12.024

Abstract ( 516 )

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In order to design structure of better impact potential for target vehicle， a finite element modeling used symmetry penalty method frequently was put forward to simulate two longitudinal rails schemes. Case 1 and 2 were separately appraised by three indexes including the vehicle deformation， deceleration and the passenger compartment intrusion: overall deformation is in line with the requirements in two cases. But because of induced slots， crumple deformation occurred in sequence from energy absorbing boxes to the longitudinal rails (from front to rear) during the impact in Case 2. Deceleration curves of Case 2 were also more consistent with principle of “the first step is taller and the second is lower” and the average passing force was more gently and cabin intrusions were less. Simulation results show that the design of longitudinal rail must have appropriate deformation guide to come true steady axial collapse mode. So the right deceleration curve of Case 2 was selected as the input value of occupant restraint system optimization.

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Feasibility Study on Screw Compressor Driven Rotor with Fixed Cross Rolling

YANG Guang， ZHANG Kang-sheng， HU Zheng-huan

2015, 36 (12): 1785-1789. DOI: 10.12068/j.issn.1005-3026.2015.12.025

Abstract ( 551 )

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As the core component of the screw compressor， driven rotor which has obvious advantages of big pitch， high tooth depth and large helical angle is manufactured by machining. A fixed cross rolling process aimed at the near-netshape forming of driven rotor with asymmetric spiral teeth at higher productivity is presented. By means of the finite element simulation and rolling experiment， the forming process of driven rotor by fixed cross rolling was carried out. That the formed asymmetric spiral teeth had a satisfied shape and uniform graduation， and elementally met the design requirements. It verifies the feasibility of the fixed cross rolling driven rotor and its application value for engineering.

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Stress Corrosion Behavior of FV520B Steel in H₂S/CO₂ Environment

SUN Jiao， CHEN Song-ying， DING Jin， LI Jian-feng

2015, 36 (12): 1790-1794. DOI: 10.12068/j.issn.1005-3026.2015.12.026

Abstract ( 550 )

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Based on simulating corrosion environments of centrifugal compressor for natural gas pipe line ， the stress corrosion cracking (SCC) of FV520B steel was studied by slow strain rate testing (SSRT) method， and the effecting law and action mechanism of concentration of H₂S and CO₂， temperature and pressure on the SCC were discussed. The results show that H₂S plays a major role on the corrosion， the stress corrosion sensitivity index (I_S) increases with the increase of concentration of H₂S， while the stress in certain range has little effect. We researched the corrosion behavior of FV520B steel by analyzing the micro fracture morphology， calculated the I_S in different environment parameters. Finally， the mathematical model of the environment parameters and the I_S of FV520B was established with the regression analysis method. The model shows that the influence of H₂S concentration and temperature on the I_S is significant， and four parameters have interaction on the I_S.

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Member Selection Model of Senior Executive Teams Based on Interval-Valued Intuitionistic Fuzzy Sets

REN Rong-rong， ZHAO Meng

2015, 36 (12): 1795-1799. DOI: 10.12068/j.issn.1005-3026.2015.12.027

Abstract ( 495 )

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A senior executive team is a crucial unit in strategy execution. Apart from team members’ strategic leadership， the matching and coordination of their competence also play an important role in organizational performance， which should be taken into consideration in member selection. By adopting the entropy of intuitionistic fuzzy sets， the weight of decision makers was determined in order to evaluate candidates’ leadership. Meanwhile， the fuzzy cross entropy in interval-valued intuitionistic fuzzy sets was applied to calculate the margin between matched and unmatched candidates. Based on the weighted geometric and arithmetic operators， the evaluation results of decision makers were aggregated for effective member selection. Finally， the model was verified by illustrating the member selection of PM company’s senior executive teams.

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Multi-stage and Multi-objective Dynamic Location Model Under the Dual-channel Supply Chain

ZHOU Jian， NIU Lin-ning， QIAN Jian-fei

2015, 36 (12): 1800-1804. DOI: 10.12068/j.issn.1005-3026.2015.12.028

Abstract ( 547 )

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Given the special characteristics of logistics distribution center location under dual-channel supply chain， a multi-stage and multi-objective dynamic location model was formulated， which combined network direct marketing and traditional retailing channel of central warehouses based on customers’ stochastic demands. This model not only considered minimizing the operation cost， but also prioritized maximizing customer satisfaction and designing the formulas of opening， operation， closing and reopening cost in the planning stage. A chief-objective approach was used to turn multiple objectives to single objectives， and a greedy heuristic algorithm was developed based on customer satisfaction. It was shown that the computation results include the optimal solution to minimizing logistics cost， thus offering a more flexible and comprehensive decision support for central warehouse location under the dual-channel supply chain.

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