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15 February 2015, Volume 36 Issue 2 Previous Issue    Next Issue
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Information & Control

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Reliable Control for Stochastic Jump Systems with Actuator Failures YANG Dong， ZHAO Jun 2015, 36 (2):  153-156.  DOI: 10.12068/j.issn.1005-3026.2015.02.001 Abstract ( 595 )   HTML   PDF (379KB) ( 975 )   For a class of stochastic jump systems， the reliable control problem is investigated. A key point of this work relaxes the special requirement of completely known transition rates to a more general form， i.e.， the transition rates are incomplete， which may lead to less conservativeness. Firstly， for the stochastic jump systems， the sufficient conditions ensuring the stochastic stability are developed. Secondly， the reliable control problem for stochastic jump systems with actuator failures is presented， and a reliable controller is designed. Finally， the design problem can be reduced to a set of LMIs feasibility problem based on the design of reliable controller. A numerical example is given to demonstrate the applicability of the main results. References | Related Articles | Metrics

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Geodesic Active Contour Model Based on Edge Diffusion Information Fitting YU Xiao-sheng， WU Cheng-dong， CHEN Dong-yue， QI Yuan-chen 2015, 36 (2):  157-162.  DOI: 10.12068/j.issn.1005-3026.2015.02.002 Abstract ( 804 )   HTML   PDF (548KB) ( 1076 )   Aiming at the sensibility of geodesic active contour model to contour initialization， a model was proposed based on edge diffusion information fitting.A diffusion functional was defined， which is related to the second derivative in the normal direction of image edge，and the edge diffusion information was obtained by solving this diffusion functional.Then， the edge diffusion information was utilized to construct a novel force field， which drives the active contour to evolve and converge to desirable edges. An efficient numerical method was used for the implementation of the proposed model in order to converge rapidly and avoid reinitialization. Experimental results on a series of real and synthetic images demonstrate that the proposed model is robust to the initial contour， and it can segment the objects with the weak edges successfully， as well as the objects with complex geometry shapes and the objects with interior and exterior boundaries. It has better segmentation performance compared with some traditional models. References | Related Articles | Metrics

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Accurate Control System of Spark Discharge Energy LI Xin-guang， ZHONG Sheng-jun， LI Wei-ye， WEI Yu-long 2015, 36 (2):  162-165.  DOI: 10.12068/j.issn.1005-3026.2015.02.003 Abstract ( 878 )   HTML   PDF (472KB) ( 872 )   By using the method of integral calculation for sampled current and voltage， an accurate experiment system was designed to control the minimum spark discharge energy of dust clouds. Through insulated gate bipolar transistors， the discharge of the residual energy in the circuit was controlled， thus the discharge time was different and controllable under the same discharge energy. And the purpose of controlling the minimum ignition energy and the discharge rates at the same time was realized based on the proposed system. The results showed that the control error of 5% could be obtained for 100J and 10J energy. When the energy was 1J， the control error was about 10%. For the aluminum powder with the diameter range of 8 ~ 13μm， when the discharge energy was 1J， the shorter the discharge time was， the easier the dust cloud was lit. It is indicated that the aluminum powder is easier to be ignited at high rate of energy input. References | Related Articles | Metrics

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Wind/Thermal Power Allocation Ratio for Transmitting Wind Power Bundled with Thermal Power CAO Xi-min， LIU Tian-qi， LI Xing-yuan 2015, 36 (2):  166-170.  DOI: 10.12068/j.issn.1005-3026.2015.02.004 Abstract ( 672 )   HTML   PDF (547KB) ( 1670 )   In order to determine the allocation ratio of wind/thermal power unit， the power output configuration model was developed based on the goal of minimizing operating costs and maximizing the transmission power. The model was solved by the equal incremental principle which considers the system constraints. The unit coal consumption， transmission channel utilization， the unit cost of power generation and nitrogen oxide emissions per unit of power generation were calculated and analyzed under the conditions of different wind/thermal power allocation ratios and wind power abandoned rates. On this basis， the impact of nitrogen oxide emissions prices on the unit cost of power generation was discussed in depth. The results show that when the price of nitrogen oxides emissions reached a certain level， wind power and thermal power can equally participate power generation scheduling， thus achieving both economical and environmental benefits of the system. References | Related Articles | Metrics

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Multiple-sub-groups Hybrid Harmony Search Algorithm XIA Hong-gang， OUYANG Hai-bin， GAO Li-qun 2015, 36 (2):  171-176.  DOI: 10.12068/j.issn.1005-3026.2015.02.005 Abstract ( 736 )   HTML   PDF (343KB) ( 1090 )   To improve the optimization performance of harmony search algorithm， a multiple-sub-groups hybrid harmony search (MHHS) algorithm is proposed. The algorithm sorts the entire harmony individuals according to the space distance between each harmony and the best harmony， and then builds multiple layers based on the ranked results， where each layer is as a unique sub-group. Different sub-groups integrate various differential adjustment strategies to broaden search ranges. Meanwhile， the communication mechanism is built to facilitate the information exchange among the multiple-sub-groups and to promote multiple-sub-groups coevolution. Simulation results show that the proposed algorithm is better than the existing algorithms such as HS， EHS， NGHS， MPSO， CLPSO， DE， ODE and IABC in terms of optimization accuracy， convergence and robustness. References | Related Articles | Metrics

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Vehicle Congestion-Avoidance Policy of Overhead Hoist Transport Systems LIU Xiao-bin， ZHOU Bing-hai 2015, 36 (2):  176-181.  DOI: 10.12068/j.issn.1005-3026.2015.02.006 Abstract ( 916 )   HTML   PDF (616KB) ( 1361 )   To solve the congestion emerging in the process of tool-to-tool transportation in the united layout of 300mm semiconductor wafer fabrications and improve the transport efficiency， a vehicle congestion-avoidance policy was proposed for scheduling overhead hoist transport (OHT) system. Firstly， a mathematical model， which considers the interrelationship of all the OHTs in the system， was built with an optimal objective function of minimizing completion time. Then a no-wait loop designing (NWL) conception and a checkpoint-based circulation policy (CBCP) were represented as a resolution of vehicle congestions. Next， the vehicle congestion-avoidance policy (VCAP) was structured by combining the K-shortest-route algorithm with time constraint sets， which was used to form a scheduling method without vehicle congestions. Finally， simulation experiments were designed and carried out to evaluate the proposed policy. The results indicate that the congestion-avoidance policy is feasible and effective. References | Related Articles | Metrics

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Virtual Machine Hotspot Degree Comprehensive Evaluation Method Based on Fuzzy Analytic Hierarchy Process YAN Yong-ming， ZHANG Bin， GUO Jun， MO Yu-yan 2015, 36 (2):  182-187.  DOI: 10.12068/j.issn.1005-3026.2015.02.007 Abstract ( 772 )   HTML   PDF (777KB) ( 782 )   Evaluating the hotspot degree of VM (virtual machine) is the critical step of the VM hotspot eliminating process. Traditional approaches of evaluating hotspot degree often monitor whether one or more threshold values being exceeded or not. The correlation among evaluation metrics and the adaptation of different metrics were not considered in the existing approaches for various services， which influences evaluation accuracy. The hotspot degree evaluation system is created， combining VM service availability and service quality factors. The subjective weight algorithm based on fuzzy analytic hierarchy process is proposed，as well as the objective weight algorithm based on maximum deviation and hotspot degree comprehensive evaluation method based on these two weights. A rule of VM coldspot or hotspot evaluation based on hotspot degree is presented. The experiment result indicates that the accuracy of the proposed method is higher than that of traditional approaches in evaluating the hotspot degree， which can efficiently reduce improper migration， with lower prices. References | Related Articles | Metrics

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An Improved Distributed Constraint Optimization Algorithm MULBS+ DUAN Pei-bo， ZHANG Chang-sheng， ZHANG Bin 2015, 36 (2):  188-193.  DOI: 10.12068/j.issn.1005-3026.2015.02.008 Abstract ( 802 )   HTML   PDF (354KB) ( 803 )   Although complete algorithms can be used in finding the optimal solution of a distributed constraint optimization problem， the resource and time consumptions are heavy. On the contrary， the shortcoming can be avoided in incomplete algorithms by obtaining suboptimal solutions. As an effective incomplete algorithm， MULBS can improve the quality of solution and reduce the runtime of solving process. However， there are shortcomings in parallel search and backtracking processes in dealing with conflict assignments. Based on thorough analysis of MULBS， an improved algorithm MULBS+ is proposed， which overcomes the disadvantages of backtrack strategy caused by conflict and parallel search strategy in the original algorithm. In MULBS+， a minimal conflict selection mechanism is introduced in backtracking. On the other hand， MULBS+ adopts global parallel search strategy based on dynamic graph partitioning which can quickly find a better solution in a constraint graph with large density. Experiments show that the proposed algorithm is better than the original one in both execution time and solution quality， except a certain increase of communication information. References | Related Articles | Metrics

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Compressed Sensing Based Data Acquisition Algorithm in Participatory Sensing System YU Rui-yun， ZHOU Yan 2015, 36 (2):  194-198.  DOI: 10.12068/j.issn.1005-3026.2015.02.009 Abstract ( 612 )   HTML   PDF (565KB) ( 942 )   A data acquisition algorithm in participatory sensing systems based on the compressed sensing theory was proposed. In this algorithm， the un-transmitted data was estimated by analyzing social relationship between mobile nodes. And then the observation matrices were refreshed using estimated data. Finally the compressed sensing algorithm was exploited to reconstruct original data according to both transmitted and estimated data. The proposed algorithm could greatly reduce the amount of data transmitted in the participatory sensing systems while still achieve good data reconstruction accuracy. The random walk mobility model was exploited in the simulations to validate the feasibility of this algorithm. The simulation results showed that， compared with the traditional compressed sensing algorithm， the amount of data transmitted over the network could be remarkably reduced without losing data fidelity， and hence the network overhead could be decreased. References | Related Articles | Metrics

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Estimation of Central Aortic Pulse Wave Based on T-tube Model Using Two-Channel Blind System Identification WANG Lu ， FENG Shu-ting， YAO Yang， XU Li-sheng 2015, 36 (2):  199-204.  DOI: 10.12068/j.issn.1005-3026.2015.02.010 Abstract ( 921 )   HTML   PDF (711KB) ( 988 )   In order to monitor cardiovascular system (CVS) non-invasively and effectively， a new method based on multi-channel blind system identification (MBSI) is proposed to reconstruct central aortic pulse wave (CAP) from two-channel noninvasive peripheral arterial pulse wave (PAP) and to identify the structures of the two cardiovascular channels. The infinite impulse response (IIR) model can be approximated by high order FIR functions， thus MBSI method is simplified. Then， the ‘T-tube’ model of CVS is employed to reconstruct the CAP from brachial pulse wave and femoral artery pulse wave. Verification results show that the MBSI algorithm can estimate CAP stably and accurately. The error of distortion rate and the error of overall energy of the proposed MBSI algorithm are less than 6% and 3%， respectively. References | Related Articles | Metrics

Materials & Metallurgy

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Microstructure and Mechanical Properties of 40Cr Steel Plate with Differential Properties in Thickness Direction CHEN Qing-an， LIU Xiang-hua 2015, 36 (2):  204-207.  DOI: 10.12068/j.issn.1005-3026.2015.02.011 Abstract ( 841 )   HTML   PDF (498KB) ( 914 )   Wear-resistance steel plates may be scrapped when they are worn to a certain degree， so it is not necessary for the steel plates to have full hardening layer in thickness direction. However， the steel plates are all treated with full size quenching now. So， a flash processing technique was used to obtain the steel plate with differential properties in thickness direction. 40Cr steel plate with thickness of 30mm was used for the experiment. The results show that after flash processing， the plates’ surface layers are acicular martensite and lath martensite， and the microstructure of transition layers changes from lath martensite and bainite to pearlite and ferrite. The hardness of surface layers is 710HV. The depth of hardening layer is 9mm， while the depth of transition layer is 5mm. The 40Cr steel plate with differential properties prepared in the experiment exhibits good impact toughness and wear-resistance. The proposed method provides a new choice for mechanical industry which needs “hard surface and tough inside” steel plates. References | Related Articles | Metrics

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Fabrication of Nb3Al Superconductor by Mechanical Alloying QI Ming， PAN Xi-feng， ZHANG Ping-xiang， YAN Guo 2015, 36 (2):  208-212.  DOI: 10.12068/j.issn.1005-3026.2015.02.012 Abstract ( 754 )   HTML   PDF (809KB) ( 971 )   By fabricating a series of different mechanical alloying Nb3Al bulks， the effects of milling time and annealing temperature on Nb3Al phase formation were investigated. X-ray diffraction， scanning electronic microscope and magnetic property measurment system were used to analyze the phase composition， microstructure and superconducting properties of the Nb3Al samples fabricated on different conditions. The results suggested that Nb-Al supersaturated solid solution was synthesized by mechanical alloying method as long as the stoichiometric elements powder was ball milled for 1h， and when the ball milling time was up to 10h， the blended powder would transform to amorphous phase. By optimizing the milling time and annealing temperature， single Nb3Al superconductor bulk was obtained successfully and its onset transition temperature was 15.3K. References | Related Articles | Metrics

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Preparation of Bulk Iron-based α″-Fe16N2 Magnetic Materials GONG Meng-ying， DU Ji-jun， TONG Wei-ping 2015, 36 (2):  213-217.  DOI: 10.12068/j.issn.1005-3026.2015.02.013 Abstract ( 773 )   HTML   PDF (934KB) ( 962 )   Bulk iron-based magnetic materials containing high content of α″-Fe16N2 phase were prepared by gas-solid reaction. The content of α″-Fe16N2 phases， phase transformation and magnetic properties in each sample with different annealing parameters were measured by XRD， optical microscope and vibration magnetometer. The result shows that the samples， prepared by gas-solid reaction nitriding， homogenizing， quenching and tempering， contain high content of α″-Fe16N2 phase. When the tempering temperature is 150℃ and the time is 4.5h， the content of α″-Fe16N2 phase is highest， reaching 50.57 wt %. The saturated magnetic pole strength is 223.6A References | Related Articles | Metrics

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Numerical Simulation on Effects of Electrode Inserting Depth on Electroslag Remelting Processes HE Zhu， LIU Yan-he， LI Bao-kuan， WANG Fang 2015, 36 (2):  218-222.  DOI: 10.12068/j.issn.1005-3026.2015.02.014 Abstract ( 866 )   HTML   PDF (1307KB) ( 929 )   The distribution of magnetic field and joule heating in the electroslag remelting process， including electrode， slag and ingot， were obtained by finite element software. The changes in the temperature profiles， the velocity fields and the magnetic fields with different inserting depth of electrode were analyzed in the electroslag remelting process coupling the magnetic field and joule heating. The results show that when the inserting depth is 15mm， an intermediate region appears between the anti-clockwise circulation eddies in the bulk of the slag which is controlled by a clockwise circulation eddy. Its size increases with the increase of electrode inserting depth. The turbulent kinetic energy drops by 21% and the maximum temperature decreases about 1% for each additional 15mm of the inserting depth. References | Related Articles | Metrics

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Effect of Ferrosilicon Addition on Direct Reduction of Ilmenite Concentrate and Its Separation Between Iron and Slag LYU Xue-wei， SONG Bing， HAN Ke-xi， ZHANG Kai 2015, 36 (2):  223-227.  DOI: 10.12068/j.issn.1005-3026.2015.02.015 Abstract ( 908 )   HTML   PDF (735KB) ( 809 )   The influence of Fe-Si additive for the reduction of ilmenite and its separation between iron and slag after smelting were discussed by the carbotherme reduction method. The results show that Fe-Si can improve the reduction rate and metallization. 84.5% of the metallization can be achieved after reduction of 30min at 1380℃. The reduction pellets’ smelting cycle can be shorten， and the separation efficiency of slag with iron and the titanium slag’s grade can be improved if adding Fe-Si. The TiO2 in the titanium slag can be reached 84.75%. The titanium slag liquidus and viscosity were calculated by FactSage software， and the result shows that the viscosity of the titanium slag has no obvious change， but the liquid area of titanium slag can be increased， which is beneficial to the accumulation， growing up and separation of metallic iron. Theoretical calculations well explain the experimental results. References | Related Articles | Metrics

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Fluid Flow Field and Stall Behavior of an Axial-Flow Fan in the Heavy-Duty Locomotive LI Yi-ming， ZHANG Lu-ning， GUO Xiao-liang， LI Bao-kuan 2015, 36 (2):  227-231.  DOI: 10.12068/j.issn.1005-3026.2015.02.016 Abstract ( 810 )   HTML   PDF (910KB) ( 790 )   Aiming at the stall of axial-flow fan happened regularly in the heavy-duty locomotive， a three-dimensional numerical model was built to study the aerodynamic performance of the axial-flow fan and predict the stall point. The coupling equations of pressure and velocities were solved with the SIMPLE algorithm， and the RNG k-ε turbulence model was also applied to this simulation. The performance parameters under several different conditions were calculated， and the fan characteristic curves were drawn. Furthermore， the internal flow rules and stall behavior of axial-flow fan were analyzed. The results indicated that the fan characteristic curves show an unstable operation region， in which the inflection point exists. Compared with the working condition， the minimum value of static pressure in the impeller area is higher， and the static pressure gradient of the blades significantly drops under the stall condition. When the stall occurs， the curvature of streamline tends to be severe， and the whirlpool zone extends at the tail.Based on the results， the stall point is predicted when the flow coefficient value is 0.201. References | Related Articles | Metrics

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Influences of EMBr on Flow and Heat Transfer in CSP Mold ZHANG Xiao-feng， ZHANG Lu-sha， WANG Bao， LIU Qing 2015, 36 (2):  232-237.  DOI: 10.12068/j.issn.1005-3026.2015.02.017 Abstract ( 704 )   HTML   PDF (960KB) ( 793 )   The magnetic field， flow field and temperature field in the CSP funnel type mold with a size of 1500mm×90mm were calculated by numerical simulation， and the influences of electromagnetic brake(EMBr) on the behavior of flow and heat transfer of molten steel with different submerged entry nozzle(SEN) in the CSP mold were researched. The results show that the impinging depth of steel jet is shortened in the mold with cow-nose nozzle when the EMBr is employed， and the maximum velocity in the free surface is decreased from 0.231m/s to 0.067m/s. The upswept trend of liquid steel mainstream disappears under the influence of EMBr when the bifurcated nozzle is adopted. The impinging strength of steel jet on the narrow side of mold is weakened. The velocity of molten steel in the upper circumfluence is reduced. The maximum velocity in the free surface decreases from 0.798m/s to 0.140m/s. Comparing synthetically the influences of EMBr on the behavior of fluid flow and heat transfer with the two kinds of SEN， the braking effect is better under the condition of bifurcated nozzle， and the quality of thin slab is improved. References | Related Articles | Metrics

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Concentrate Grade Prediction of Gold Ore Based on GA-BP Neural Network LIU Qing， YUAN Wei， WANG Bao， PENG Liang-zhen 2015, 36 (2):  237-240.  DOI: 10.12068/j.issn.1005-3026.2015.02.018 Abstract ( 816 )   HTML   PDF (477KB) ( 837 )   Two prediction models for concentrate grade of gold mine were established respectively by using BP neural network and GA-BP neural network method on the basis of investigation in actual production. 978 groups of data were gathered from actual production， from which the 770 groups was selected for establishing the models， among which 120 groups was used for verification. By analyzing the predictive errors of two models， it is approved that the prediction model based on GA-BP neural network can provide better accuracy: when the relative prediction errors are within ±2%， the prediction accuracy reaches 97.5%. References | Related Articles | Metrics

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Application of Topological Structure to Power Generation Nodes in Iron and Steel Plant LIU Jing-yu， CHANG Yong 2015, 36 (2):  241-244.  DOI: 10.12068/j.issn.1005-3026.2015.02.019 Abstract ( 765 )   HTML   PDF (926KB) ( 942 )   Against a background of electrical energy management of iron and steel plant， the distributed network structure of power generation nodes was established by using topology knowledge in iron and steel plant， with its evaluation indices given. Then， the principle of optimizing the network structure was proposed. It is shown that the distance between the nodes(coke dry quenching power generation， combined cycle power plant (CCPP) and blast furnace) and between the equipment such as steam pipe， gas pipe are as short as possible. The coke dry quenching equipment， CCPP and blast furnace should be located in a straight line. Six kinds of topological structures most suitable for iron and steel plant were developed on the basis of the optimization principle， thus reducing the energy consumption and the electricity cost. References | Related Articles | Metrics

Mechanical Engineering

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Reliability Allocation of CNC Machine Tools Based on Failure Information and Fuzzy Mathematics ZHANG Yi-min， JIA Jing-cun， HUANG Xian-zhen 2015, 36 (2):  245-249.  DOI: 10.12068/j.issn.1005-3026.2015.02.020 Abstract ( 688 )   HTML   PDF (529KB) ( 775 )   Based on the fuzzy mathematics and the failure information， a reliability allocation method for CNC machine tools was proposed. First， the fault record data of a type of CNC machine tools were sorted out， and the whole machine system was divided into ten subsystems. Then， the reliability functions for the whole system and the subsystems were established according to the statistical collation of the failure records. An allocation model of the failure rate based on the fuzzy mathematics and entropy weight methods was thus developed with four factors considered. This method can solve the reallocation of the machine’s reliability， thus enhancing the reliability of the whole system. References | Related Articles | Metrics

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Path Insertion Loss Analysis of Vibration Transfer Path Systems ZHAO Wei， ZHOU Na， ZHANG Yi-min 2015, 36 (2):  250-254.  DOI: 10.12068/j.issn.1005-3026.2015.02.021 Abstract ( 888 )   HTML   PDF (374KB) ( 1130 )   In order to analyze the vibration characteristics of mechanical systems from vibration transitivity， a model of vibration transfer path system composed of excitation sources， transfer paths and recipients was established. Among the subsystems， transitivity of transfer paths determined the response characteristics of recipients and became an important part in vibration and noise reduction system. A concept of path insertion loss was proposed and the convenient and effective formula was derived using the path separation method. So the path contributions can be evaluated based on the corresponding results in frequency domain. In a numerical example， the results were satisfying， which further indicated the effectiveness of path insertion loss as an evaluation of path contribution. References | Related Articles | Metrics

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Probabilistic Analysis for Cutting Force in Orthogonal Cutting Using Monte-Carlo Method HUANG Xian-zhen， CAO Hui， ZHANG Yi-min 2015, 36 (2):  254-258.  DOI: 10.12068/j.issn.1005-3026.2015.02.022 Abstract ( 713 )   HTML   PDF (608KB) ( 827 )   Considering the effect of random factors， Monte-Carlo numerical simulation method was used to study the statistical distribution of cutting force in the process of metal cutting. The model of parallel shear zones unequally divided was established to solve the cutting velocity， shear strain rate and shear strain. Control equation of metal cutting materials and temperature control equation for shear zone were constructed to calculate shear stress and cutting force. Extracted samples from the distribution information of cutting parameters were substituted into the cutting force model to calculate the cutting force and its probability characteristics. Thereby an orthogonal cutting force prediction method was presented based on Monte-Carlo method. References | Related Articles | Metrics

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Vehicle Braking Features in Braking Energy Recovery Method with Cylindrical Helical Spring MA Ming-xu， HUO Xiao-pei， LIU Gong-yu， KONG Xiang-wei 2015, 36 (2):  259-263.  DOI: 10.12068/j.issn.1005-3026.2015.02.023 Abstract ( 917 )   HTML   PDF (459KB) ( 806 )   The experimental equipment for braking energy recovery based on common bicycles was designed and produced， with a cylindrical helical spring as energy storage component. Traditional friction braking of common bicycle and energy recovery braking of experimental bicycle were analyzed in order to get their mathematical models. The actual braking features were experimentally measured and contrasted. The experimental results show that braking process feature of energy recovery bicycle is similar to the traditional friction braking bicycle， and their feature curves have the same development tendency. Conclusions are made that the experimental braking energy recovery bicycles can meet the braking requirements of riders， and vehicle braking with braking energy recovery method using cylindrical helical spring can conform to comfort condition. References | Related Articles | Metrics

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Experimental Study on Influencing Factors of Surface Quality in Micro-grinding Plastic Materials GONG Ya-dong， WU Ai-kui， CHENG Jun， ZHANG Bi 2015, 36 (2):  263-268.  DOI: 10.12068/j.issn.1005-3026.2015.02.024 Abstract ( 766 )   HTML   PDF (1169KB) ( 865 )   TC4 titanium alloy and H62 brass， as two kinds of typical plastic materials， were studied in micro-scale grinding experiment. The surface micro-morphology was investigated by using microscope with super depth of field and three-dimensional profiler. The surface formation mechanism in micro-grinding and the effect of minimum chip thickness were analyzed theoretically. Based on the characteristics of micro-grinding， both single factor and orthogonal tests were carried out with different processing parameters. The effects of grinding parameters， such as grinding speed， grinding depth and feed speed， were investigated on the micro-grinding surface quality of the plastic materials. The effects of head diameters， grit of micro-grinding rod and grinding modes on the specimen’s surface quality were also studied. The result shows that the surface roughness of ground workpiece decreases firstly and then increases with increasing the grinding depth， and the processing quality of side grinding is better than that of the groove grinding. References | Related Articles | Metrics

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Theoretical Calculation on Cutting Heat and Its Influence Factors Analysis in Ice Core Drilling CAO Pin-lu， BAI Yang， LIU Chun-peng， YANG Cheng 2015, 36 (2):  269-274.  DOI: 10.12068/j.issn.1005-3026.2015.02.025 Abstract ( 486 )   HTML   PDF (585KB) ( 932 )   In order to analyze the temperature changes of ice cuttings in drilling process， a mathematical model was constructed based on metal cutting theory. The factors which affected the cutting temperature were studied， including drilling pressure， rotation speed of drilling bit， cutting edge angle， cutting depth， friction coefficient， ice shearing strength， heat conduction coefficient of cutters and so on. The results show that the parameters mentioned all have a certain effects on cutting temperture， particularly the friction coefficient， and when it increases to 0.3， the temperture of the ice cuttings can raise 9.11℃. Moreover， the rotation speed of the drilling bit and the angle of the cutting edge also affect the temperature of ice cuttings. The temperature increases from 2.35℃ to 4.35℃ with the rotation speed increasing from 30r/min to 130r/min， while it decreases from 3.48℃ to 2.42℃ with an increasing of the cutter edge angle from 15° to 75°. References | Related Articles | Metrics

Resources & Civil Engineering

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Underpinning Technique Based on Cover-Cut Method for Underground Passage Project at Shenyang Railway Station CHEN Chen， ZHAO Wen， LI Shen-gang， PANG Yu-bin 2015, 36 (2):  274-279.  DOI: 10.12068/j.issn.1005-3026.2015.02.026 Abstract ( 607 )   HTML   PDF (693KB) ( 729 )   The excavation process of the underground passage under the east station house at Shenyang station was simulated by FEM. The land subsidence， deformation of retaining piles， inner force of stand columns， and the deformation of underlying tunnel were analyzed. The results show that underpinned plates can limit the horizontal displacement of retaining piles and the upheaval of the pit bottom effectively， thus controlling the land subsidence. The upheaval of the soil at the pit bottom caused by the excavation process leads to the increase of the axial force of stand column， which may affect the stability of the support structure system. Moreover， the excavation process has an obvious effect on horizontal and vertical displacement of underlying tunnel， where one kind of convergent deformation happens in the tunnel in the form of ‘the horizontal compression and the vertical stretch’. The impact of the cross constuction of foundation pit on the ambient environment and structures cannot be ignored. References | Related Articles | Metrics

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Extraction of Joint Information of Rock Masses Based on 3D Laser Scanning Technology JING Hong-di， LI Yuan-hui， ZHANG Zhong-hui， LIU Zhao-sheng 2015, 36 (2):  280-283.  DOI: 10.12068/j.issn.1005-3026.2015.02.027 Abstract ( 925 )   HTML   PDF (517KB) ( 1036 )   Based on 3D laser scanning technology and geological analysis， an experiment was conducted to study the information extracted from structural plane in underground mining engineering. Z+Flasercontrol and Geomagic Studio were used to preprocess the cloud information of surround rock point. A point cloud data processing system was developed by Java language， and the Dips software is used to analyze the information of structural planes. The accuracy and feasibility of this system were validated against the manual measurements. It is shown that this method provides advantages in terms of fast， automatic and distant measurement， compared with the traditional method. References | Related Articles | Metrics

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Clustering Analysis of Dominative Attitudes of Rock Mass Structural Plane Based on Firefly Algorithm SONG Teng-jiao， CHEN Jian-ping， ZHANG Wen， SONG Sheng-yuan 2015, 36 (2):  284-288.  DOI: 10.12068/j.issn.1005-3026.2015.02.028 Abstract ( 748 )   HTML   PDF (707KB) ( 938 )   Traditional graphic analysis is inadequate and greatly influenced by subjective experience. A new method based on firefly algorithm is proposed to partition the discontinuity orientation data. The sine of the acute angle between the unit normal vector of two discontinuities is used to quantify the distance between the orientation of these discontinuities. Then， the fuzzy objective function is established and firefly algorithm is chosen to search the optimal clustering centers. At the same time， the boundaries between different sets are determined. Since the firefly algorithm has the outstanding ability of global optimization and a fast convergence speed， the new algorithm has the advantages of time saving and high efficiency. Finally， this new method is applied in discontinuity orientation data partition at Songta dam site， Nujiang River. The results indicate that the new approach is reasonable and has obvious superiority. References | Related Articles | Metrics

Management Science

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Combined Model in Supply Chain with Capacity Constraint WANG Hai-ying， DING Hua， ZHANG Cui-hua， WANG Lin 2015, 36 (2):  288-291.  DOI: 10.12068/j.issn.1005-3026.2015.02.029 Abstract ( 741 )   HTML   PDF (308KB) ( 677 )   A three-level supply chain composed of a supplier， a manufacturer and a distributor was considered， and the three members of the system are respectively called as first echelon， middle echelon and last echelon. Based on the existing supply chain model where the first and last echelons have capacity constraints， a new integrated lot-sizing model for the three-level supply chain was presented in which the middle echelon has capacity constraints. A new dynamic planning algorithm based on the mixed pull-push rules was proposed to determine the optimal material ordering batches in polynomial time. Some proven theorems show that the global optimal solution should be achieved. The proposed algorithm was explained via solving a simple problem. References | Related Articles | Metrics

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Control of VaR of Rebar in Inventory Financing HUANG Yun-fei， ZHUANG Xin-tian， WANG Sha-sha， LI Xiao-qing 2015, 36 (2):  292-296.  DOI: 10.12068/j.issn.1005-3026.2015.02.030 Abstract ( 688 )   HTML   PDF (517KB) ( 744 )   Aiming at the price risk of inventory financing in steel market， the prices of rebar were selected as the sample data to calculate the risk rate and efficiency loss rate based on empirical values. The results calculated using the empirical values were compared with that using the historical simulation method based on the values at risk(VaR)，and it was found that the length of sample period affected the performance of calculation result of historical simulation method. The historical simulation method was suitable for inventory financing in short term. The back testing of the calculation results shows that pledge rate determined by VaR is more effective on the control over the price risk. References | Related Articles | Metrics

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Influencing Factors Analysis and Trend Forecasting of China’s Carbon Emissions——Empirical Study Based on STIRPAT and GM(1，1) Models TONG Xin， CHEN Kai， LI Gang 2015, 36 (2):  297-300.  DOI: 10.12068/j.issn.1005-3026.2015.02.031 Abstract ( 1350 )   HTML   PDF (337KB) ( 1685 )   STIRPAT (stochastic impacts by regression on population， affluence， and technology) model is used to analyze the influencing factors of China’s carbon emissions， and gray model GM(1， 1)is applied to the prediction of emissions from 2012 to 2020. The analysis shows that urbanization，economy growth， industrial structure， energy prices， population， energy structure and foreign trade are the main factors to aggravate the emissions， while technology progress plays an important role in the inhibition of emissions. Among the factors mentioned， population and industrial structures are the two dominant factors. Based on the GM(1， 1)， China’ carbon emission is predicted， showing the pressure of reducing carbon emissions is great. Therefore， the governance of carbon emission should synthetically consider the factors mentioned above. References | Related Articles | Metrics

Mathematics

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Fixed Point Theorems of Cone Expansion and Compression of Concave Functional Type in Product Space ZHANG Guo-wei， ZHANG Xiu-ping 2015, 36 (2):  301-304.  DOI: 10.12068/j.issn.1005-3026.2015.02.032 Abstract ( 623 )   HTML   PDF (284KB) ( 765 )   A product space of normed linear spaces is considered， and the cone in the product space is produced by the cones in its factor spaces. A completely continuous operator is in the product space defined on the bounded closed set which is the intersection of the cone with two closed balls， and the range is in the cone. Under the mixed cone expansion and compression conditions that are expressed through a class of nonnegative， positively homogeneous， concave functionals on the cone， some fixed point theorems about the completely continuous operator are proved by constructing methods and converting them into the problems of Schauder type. It is illustrated by example that the concave functionals needed here are easily constructed in a common space and on a cone in it. References | Related Articles | Metrics