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15 October 2015, Volume 36 Issue 10 Previous Issue    Next Issue
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Information & Control

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Temperature Sensor with Photonic Crystal Fiber Filled with Ethanol as Probe GAO Peng， ZHAO Yong， LI Jin 2015, 36 (10):  1369-1373.  DOI: 10.3969/j.issn.1005-3026.2015.10.001 Abstract ( 714 )   HTML   PDF (470KB) ( 949 )   A high birefringence photonic crystal fiber(HiBi-PCF) loop mirror structure was proposed with a reflective independent probe， in which the thermo-optic effect of ethanol was used to modulate linearly photonic crystal fiber birefringence. The Sagnac interference optical path difference was changed by the birefringence variations， resulting in the linearly changes of spectral intensity in a certain temperature region. Based on the above principle， high sensitive temperature measurement could be implemented. The structure improves the shortcoming of the traditional ring inner structure affected by external disturbance， and makes it possible to build a distributed sensing system in practical application. The experimental results showed that the refractive index of ethanol changes versus the measured temperature linearly with the sensitivity of 4.45e-4/℃. The birefringence change rule of ethanol-filled HiBi-PCF with temperature was also indicated with the sensitivity of 0.015625/℃. In addition， the change rule of output light intensity with temperature between 20~40℃ was tested with the sensitivity of 0.0031mW/℃. The formation mechanism of interference spectrum was demonstrated by using the Jones matrix theory， with the interference spectrum equation obtained. References | Related Articles | Metrics

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BCG Signal Intelligent Diagnosis Method Based on Cloud Model JIANG Fang-fang， SONG Shao-xiu， CHENG Jia-bin， XU Hui 2015, 36 (10):  1374-1377.  DOI: 10.3969/j.issn.1005-3026.2015.10.002 Abstract ( 741 )   HTML   PDF (425KB) ( 763 )   The method to diagnose intelligently abnormal information from heart rate by BCG signal ( ballistocardiogram signal) based on cloud model was studied. The qualitative expert diagnosis system and quantitative computer aided diagnosis system were combined by using the cloud model， and the expert diagnosis process was simulated. A cloud model for abnormal heart rate intelligent diagnosis was established. Then， distribution curve diagram of JJ interval in BCG signal was constructed， and the model parameters were adjusted automatically to establish the intelligent diagnosis mechanism. The signal acquisition system in our laboratory was used to extract 2000 groups of BCG signal as the sample object， the feasibility of the proposed method was verified by comparing with the traditional standard threshold method. The experiment results showed that the automatic clustering accuracy of the proposed method could reach 90.2%， which was 2 percentage points higher than that of the traditional method. References | Related Articles | Metrics

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Hovering Control of Hex-Rotor Aircraft Based on Optical Flow SHI Tian-wei， WANG Hong 2015, 36 (10):  1378-1383.  DOI: 10.3969/j.issn.1005-3026.2015.10.003 Abstract ( 824 )   HTML   PDF (798KB) ( 1530 )   A nonlinear controller was proposed to realize the hovering control for the hex-rotor aircraft by using the inertial optical flow. Meantime， an auxiliary hovering control system was presented to overcome the influence of external factors. Firstly， the spherical camera was used to get the image of target plane， and the projection from target point to camera lens was realized by dynamic mapping. Then the translational optical flow of target point was obtained by comparing the two continuous time images. Finally， the divergent translational optical flow was utilized as the feedback to implement the stable hovering control for the hex-rotor aircraft. The indoor textured floor was selected as the target plane， and this experiment was tested ten times totally. The actual flight tests showed that the errors on horizontal and vertical directions were all less than ±5cm， which verified the feasibility of the proposed nonlinear controller and auxiliary hovering control system. References | Related Articles | Metrics

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Epileptic Seizure Prediction Based on Multivariate Hilbert Frequency Domain Model HAN Ling， WANG Hong， LI Chun-sheng 2015, 36 (10):  1383-1387.  DOI: 10.3969/j.issn.1005-3026.2015.10.004 Abstract ( 668 )   HTML   PDF (695KB) ( 715 )   Epileptic seizure with sudden and repeatability poses a great threat to patient safety. To effectively predict the epileptic seizure， an epileptic seizure prediction method based on multivariate Hilbert frequency domain model was proposed. Hilbert marginal spectrum， Hilbert weighted frequency and Hilbert marginal spectrum change direction were composed to a three dimensional feature vector as multivariate Hilbert frequency domain model， and then put it into support vector machine (SVM) to prediction epileptic seizure. The epileptic seizure prediction method was used to assess the prediction results. Experimental results showed that when the multivariate Hilbert frequency domain model was used to predict epileptic seizure for δ rhythm and θ rhythm， the seizure prediction horizon was 30~45minutes， so that patients could have enough time to take measures to deal with seizures. The seizure occurrence period was 5~10minutes， thus， the waiting time was shortened and the anxiety of patient was reduced. Compared with a variety of relevant methods， this method has lower false prediction rate and higher prediction sensitivity. References | Related Articles | Metrics

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Optimization Model of Steam Coal Blending in Coal-Fired Power Plant ZHAO Jian， LIU Shi-xin 2015, 36 (10):  1388-1392.  DOI: 10.3969/j.issn.1005-3026.2015.10.005 Abstract ( 602 )   HTML   PDF (232KB) ( 828 )   According to the blending scheme and the relation between single coal and blended coal used in the factory， 0-1 mixed integer variables were introduced to limit the number of single coals in blend， and a resource-constrained 0-1 mixed integer programming model based on the minimum blending cost as the objective was established. By combining technical transformation and equipment upgrading and permitting the coal’s quality indicators in blend overflow the given boundary values， the corresponding penalty functions were added in objective functions， and the model was revised to obtain a lower unit price of the standard coal. The solution solved by CPLEX is reasonable that the unit price of the standard coal declines 3.6%， but the change of the coal’s quality indicators in blend is no more than 0.4%. References | Related Articles | Metrics

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Optimization Model for Single Bus Route Schedule Design Problem with Stochastic Travel Time WU Ying-hui， TANG Jia-fu ， GONG Jun 2015, 36 (10):  1393-1398.  DOI: 10.3969/j.issn.1005-3026.2015.10.006 Abstract ( 563 )   HTML   PDF (772KB) ( 748 )   A single bus route schedule design (BRSD) problem with stochastic travel times was studied.The effect of the bus operators’ preference on the optimal schedule design was considered， and a stochastic programming model was established for the BRSD problem with the objective of minimizing the weighted sum of the expected value of random schedule deviation and the expected value of overtime for the bus running. The proposed model was transformed into a linear programming model by using Monte Carlo simulation and inequality constraints， and the model was solved by the optimization solvers CPLEX. Finally， a numerical example was given to analyze the sensitivity of the following characteristics. The first is the available bus route travel time， and the second is the weight coefficient for the schedule deviation when bus arrives late. The third is the weight coefficient of the overtime for the bus running and the last is the variances in the bus travel times. References | Related Articles | Metrics

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Simulation and Decision-Making System in Burden Distribution of Blast Furnace ZHANG Jun， SONG Xiang-man 2015, 36 (10):  1398-1402.  DOI: 10.3969/j.issn.1005-3026.2015.10.007 Abstract ( 702 )   HTML   PDF (578KB) ( 639 )   For the difficulty to obtain a stable and satisfying ore to coke ratio indicator by manual decisions and unable to make the burden distribution adjustment timely and accurately， a simulation and decision-making system based on operation optimization was proposed in burden distribution. Taking the minimum deviation between the index value and the optimal value of practical burden surface as the objective function， an operation optimization model was built. A differential evolution algorithm was used to solve the proposed model. The system can improve the stability of the furnace condition after the actual operation of blast furnace， meet the requirements of scientific and stable control of ore to coke ratio and give the adjustment program of burden distribution in time when the furnace condition changes. The practical application results showed the effectiveness of the system. References | Related Articles | Metrics

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Improved Novel Global Harmony Search Algorithm ZHAI Jun-chang， GAO Li-qun， OUYANG Hai-bin， LIU Hong-zhi 2015, 36 (10):  1403-1407.  DOI: 10.3969/j.issn.1005-3026.2015.10.008 Abstract ( 533 )   HTML   PDF (236KB) ( 661 )   To improve the optimization performance of harmony search algorithm， an improved novel global harmony search (INGHS) algorithm was proposed. The harmony memory diversity was defined by the difference vector norm to implement dynamically position updating， and the mutation operation was employed to update harmony memory. A new harmony generated with dynamically updating strategy made the algorithm having excellent global search performance in the early states and local search capability during the final stages of the optimization process， which avoided the algorithm trapped in local optimal. Finally， the simulation for 7 benchmark functions were carried out using the proposed algorithm and other state-of-the-art HS variants that reported in the recent literature. The simulation results demonstrated that the proposed algorithm has a higher precision. References | Related Articles | Metrics

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Production Design Method Based on Latent Variable Model for Industry Processes WANG Xiao-gang， SHA Yi， ZHU Li-chun 2015, 36 (10):  1408-1411.  DOI: 10.3969/j.issn.1005-3026.2015.10.009 Abstract ( 544 )   HTML   PDF (448KB) ( 681 )   In view of determining the manipulated variables in the industrial control process and solving the null space problems during the production design of the complex industrial process， an in-depth study about the application strategy of the principal component regression was done on the basis of the existing multi-latent variable modeling methods. In addition， a production design strategy based on the latent variable was proposed. Compared with the standard regression model， the advantages of the multivariate latent variable method on solving production design problems were revealed. The proposed design method could not only satisfy the requirement of product quality， but also be consistent with the correlation structure of the historical condition and scope， which could be regarded as a feasible scheme to solve the null space problems. The simulation results showed the effectiveness of the designed method for solving production design problems of null space. References | Related Articles | Metrics

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Top-k Spatial Preference Query for Group Nearest Neighbor CHEN Mo， YANG Dan， GU Yu， YU Ge 2015, 36 (10):  1412-1416.  DOI: 10.3969/j.issn.1005-3026.2015.10.010 Abstract ( 599 )   HTML   PDF (362KB) ( 737 )   Spatial preference query is a popular focus of the current research on spatial queries. However， the present spatial preference queries cannot be used in the location-based services for group users. To solve this problem， a novel type of spatial preference query， namely， Top-k spatial preference query for group nearest neighbor (TSPG) was proposed， which retrieves the k λ-subsets with the highest score through finding λ-subsets group nearest neighbors of the feature objects. Two algorithms， namely， TSPQ-G and TSPQ-G* were designed for efficient query processing. Based on the TSPQ-G， the TSPQ-G* was developed by performing spatial pruning strategies and efficient traversal strategies of feature objects index， which effectively reduces I/O cost and improves query efficiency. Experimental results on several datasets demonstrated the effectiveness of the proposed algorithms for different setups. References | Related Articles | Metrics

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Data Access Control Scheme Based on CP-ABE in Cloud Storage GAO Jian， ZENG Kang， JIN Heng-zhan， ZHOU Fu-cai 2015, 36 (10):  1416-1421.  DOI: 10.3969/j.issn.1005-3026.2015.10.011 Abstract ( 699 )   HTML   PDF (480KB) ( 815 )   A hybrid encryption and data access control scheme based on CP-ABE with convergent encryption technology was constructed by combining the application environment of cloud storage. Three entities are included in the proposed scheme which are key distribution center， customers and cloud server. It was indicted that the proposed scheme is efficient， flexible， fine-grained which can also improve the space utilization of the storage server. The data origin authentication and the data integrity certification were supported by using signature authentication technology. Theoretical analysis and experimental test showed that the proposed scheme has highly practical value. References | Related Articles | Metrics

Materials & Metallurgy

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Effects of Y on Microstructure and Properties of As-Extruded Mg-5Li Alloys ZU Guo-yin， DU Peng， SONG Hong-quan， SUN Shi-liang 2015, 36 (10):  1422-1426.  DOI: 10.3969/j.issn.1005-3026.2015.10.012 Abstract ( 606 )   HTML   PDF (909KB) ( 707 )   With the protection of surface covering agents and argon protection， the Mg-5Li-x Y(x=0， 1， 2， 3， 4) alloys were prepared by conventional casting methods. The effects of rare earth on microstructure and mechanical properties of the as-extruded alloys were investigated. The results showed that the RE compound Mg24Y5 generated after adding Y into the Mg-5Li alloy. The dynamic recrystallization arose during the hot extrusion process， leading to a large number of equiaxed grains appeared. The dispersive distribution of Mg24Y5 phase hindered the growth of the grains during the dynamic recrystallization， which led to the grain refinement. The as-extruded Mg-5Li-3Y alloy achieved the best mechanical property: the tensile strength and elongation reached up to 231.63MPa and 9.35%， respectively. The fracture mode of the alloy is mainly ductile fracture. References | Related Articles | Metrics

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Effects of Casting Process Parameters on Macrostructure and Microstructure of A390 Alloy Hollow Billet Produced by DC Casting ZUO Ke-sheng， ZHANG Hai-tao， QIN Ke， CUI Jian-zhong 2015, 36 (10):  1426-1430.  DOI: 10.3969/j.issn.1005-3026.2015.10.013 Abstract ( 612 )   HTML   PDF (1011KB) ( 747 )   DC casting was used to produce A390 alloy hollow billet. The effects of the casting speed and temperature on the macrostructure and microstructure of A390 alloy hollow billets were studied. The results showed that the distribution of primary Si in the hollow billet became more even and the average size of primary Si particle decreased gradually with the increase of the casting speed from 90mm/min to 120mm/min and casting temperature from 800℃ to 850℃，respectively. The optimum casting process parameters for the A390 alloy hollow billets of 164mm/60mm were obtained with the casting speed of 110mm/min and casting temperature of 850℃. The primary Si particles uniformly distributed with their average size less than 26μm obtained under the optimum casting process parameters. The ultimate tensile strength and elongation at the inner wall of the hollow billets were 264MPa and 0.5%， respectively. References | Related Articles | Metrics

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High Precision Outlet Temperature Control Methods of Ultra Fast Cooling for X80 Hot-Rolled Strips LI Xu-dong， YUAN Guo， JIANG Xiao， WANG Guo-dong 2015, 36 (10):  1431-1435.  DOI: 10.3969/j.issn.1005-3026.2015.10.014 Abstract ( 599 )   HTML   PDF (644KB) ( 720 )   According to the rolling process of X80 pipeline steels and the basic theories of heat transfer， a cooling control model of ultra-fast cooling (UFC) was established. A UFC control strategy of X80 pipeline steel was developed by simulating the temperature field of UFC process for the steel strip. The results showed that the uniform mode starting initial configuration and the use of forward additional strategies were benefited for the high UFC control precision and low temperature deviation between the steel centre and surface. To deal with influences of the technological condition fluctuations， an adaptive system of UFC was developed to correct temperature deviation in real-time and that between steel coils at UFC outlet. A satisfied result was achieved in field practice， which provided technology supports for the implementation of controlled cooling process. References | Related Articles | Metrics

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Transition Zones in Flexible Stretch Forming for Surface Parts CHENG Yan-yan,LI Ming-zhe,XING Jian,WANG You 2015, 36 (10):  1435-1440.  DOI: 10.3969/j.issn.1005-3026.2015.10.015 Abstract ( 635 )   HTML   PDF (928KB) ( 848 )   According to the characteristics that the multi-gripper stretch forming machine can realize the flexibility of clamping and stretching， finite element models of rectangular and trapezoidal sheet metal were built for surface parts of trapezoidal projection plane， and numerical simulations of different transition zones for rectangular and trapezoidal metal sheets were conducted. The results showed that with the decrease of the maximum length of the transition zone， the conformability of the sheet metal to the forming die was increased， the forming force together with the maximum strain of the formed parts decreased while the strains and thickness of the effective forming zone distributed more uniformly and the formability was much better. Stretch forming experiments were done for the surface part of trapezoidal projection plane， and the experimental results were coincident with the numerical simulation results， which proved the validity of simulation. The multi-gripper stretch forming machine can reasonably choose the transition zone shape according to the shape of forming die， which improves forming quality and reduces the material and stretch forming costs. References | Related Articles | Metrics

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Compressive Strength of Vanadium Titanium Magnetite Hot Briquette Based on Taguchi Method ZHAO Wei， CHU Man-sheng ， TANG Ya-ting， TANG Jue 2015, 36 (10):  1441-1444.  DOI: 10.3969/j.issn.1005-3026.2015.10.016 Abstract ( 560 )   HTML   PDF (226KB) ( 655 )   The Taguchi method was used to explore the important influence factors on the compressive strength of vanadium titanium magnetite hot briquettes， and then the contribution rates of these factors to the compressive strength were calculated through the signal-to-noise ratio analysis. Finally， the best preparation conditions of vanadium titanium magnetite hot briquettes were established. The results showed that among the three processing parameters including the hot-briquetting temperature， carbon ratio and coal particle size， the coal particle size was the most important factor to the compressive strength， and its contribution rate is up to 79.99%， the contribution rates of the hot-briquetting temperature and the carbon ratio were 15% and 3.63%， respectively. The optimized parameters of the preparation process of vanadium titanium magnetite hot briquette are as follow: hot-briquetting temperature 300℃， coal particle size less than 75μm， carbon ratio 1.8. Verification experiments were conducted with the optimized parameters， and the average compressive strength of the vanadium titanium magnetite hot briquette is up to 1152.1N. References | Related Articles | Metrics

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Separation Between Vanadium and Iron in Acid Leaching Solution of Converter Vanadium Slag Without Calcination ZHANG Ying， ZHANG Ting-an， LYU Guo-zhi， LIU Zhuo-lin 2015, 36 (10):  1445-1448.  DOI: 10.3969/j.issn.1005-3026.2015.10.017 Abstract ( 643 )   HTML   PDF (472KB) ( 779 )   In view of a new process of leaching the converter vanadium slags with titanium dioxide waste acid under the pressure without calcination proposed by our research group， V extraction from the solution which using waste acid leaching vanadium slag was studied using P204 as the extraction agent. The results showed that the reduction of ferric iron into ferrous iron by Na2SO3 as a pretreatment reducing agent prevented ferric irons co-extracted into the leaching liquid. Under the optimal technological condition: at room temperature， leaching solution original pH of 2.5， the volume ratio of the aqueous phase to oil phase of 1∶3 and the shaking time of 4min， the extraction rate of V is more than 98.61%， and the separation factor between V and Fe is up to 135.3 using the 20%P204 with 10%TBP synergistic extraction system. References | Related Articles | Metrics

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Preparation of Lithium-Rich Clinker in New Vacuum Aluminothermy Reduction of Lithium Process DI Yue-zhong， TANG Cheng-wei， ZHAO Kang， FENG Nai-xiang 2015, 36 (10):  1449-1453.  DOI: 10.3969/j.issn.1005-3026.2015.10.018 Abstract ( 649 )   HTML   PDF (543KB) ( 570 )   A new vacuum aluminothermy reduction of lithium process was developed， in which lithium hydroxide， alumina and calcium oxide mixture were used as raw materials. Lithium-rich clinker was prepared by calcining the mixture of raw materials. Metal lithium and reduction slag contained the 12CaO·7Al2O3 which was used to form aluminum hydroxide were produced by the vacuum aluminothermy reduction process. Effects of briquette pressure， calcination temperature and time on the burning loss rate and lithium reduction rate were investigated. The result showed that the burning loss rate remained about 34% under the conditions of briquette pressure 30MPa， calcination temperature 750~800℃ and calcination time 60~90min. The lithium reduction rate was relatively high when the lithium-rich clinker obtained under the above conditions were used to vacuum aluminothermy reduction under the conditions of reduction temperature 1100℃， reduction time 90min and theoretical aluminum addition mass. This kind of calcination process was suitable to the preparation of lithium-rich clinker for the new vacuum aluminothermy reduction of lithium. References | Related Articles | Metrics

Resources & Civil Engineering

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Supporting Optimization of Underground Oil Storage Caverns Based on Orthogonal Experimental Design ZHAO Xing-dong， LIU Jie， XU Ji-tao， WEN Xin-liang 2015, 36 (10):  1453-1456.  DOI: 10.3969/j.issn.1005-3026.2015.10.019 Abstract ( 576 )   HTML   PDF (783KB) ( 517 )   According to the actual engineering of oil storage caverns， the orthogonal experiments were conducted. Four factors were selected， including the bolt length， the bolt spacing， the thickness of shotcrete and steel arch spacing， and three levels were set for each factor so that nine test schemes were performed. Then the corresponding numerical simulation by using FLAC3D was conducted in order to optimize the supporting scheme. The key point displacement and plastic zone volume were taken as the evaluating index. Results showed that the steel arch spacing was the key parameter for supporting other than the bolt length and bolt spacing. An optimized supporting scheme of 5m bolt length with bolt spacing of 2m × 2m， a shotcrete thickness of 120mm and a steel arch spacing of 1.5m were adopted， which could control the stability of the surrounding rock of these caverns effectively and give some references to similar projects. References | Related Articles | Metrics

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Stress Migration and Destressing Parameters of Roadway HE Rong-xing， REN Feng-yu， DING Hang-xing， SONG De-lin 2015, 36 (10):  1457-1460.  DOI: 10.3969/j.issn.1005-3026.2015.10.020 Abstract ( 644 )   HTML   PDF (807KB) ( 581 )   The rib spalling and roof falling were encountered during tunneling process of the -95m sublevel drifts in 4# stope of Beiminghe iron mine. Although lots of plastic U-shaped arches was mounted， the large deformation and failure of the drift were not under control. Numerical simulation by flac3D was utilized to study the stress distribution in the stope route under different distressing parameters. Results showed that destressing is effective in different part of the drift.The shear stress in the invert and the maximum principal stress in invert， side walls and bottom angle in the drift are decreased by destressing.While the maximum principal stress in the roof is increased during destressing. Destressing width affect the distress result obviously. The destressing width should exceed the boundary of the drift by 1~2m. The destressing method in this project reduced the stress concentration effectively and 150000 tons of ores were mined safely， which contributed a new idea for mining in high stress rock mass. References | Related Articles | Metrics

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Mechanism of Water-Weakening Process of Mudrock Observed Using Real-Time CT YANG Cheng-xiang， SONG Lei-bo， WANG Gang， GONG Yan-hua 2015, 36 (10):  1461-1465.  DOI: 10.3969/j.issn.1005-3026.2015.10.021 Abstract ( 897 )   HTML   PDF (640KB) ( 732 )   The computerized tomographic scanner (CTS) was used to investigate the dynamic weakening process of the mudrock meso-structure when interacting with water. A series of real-time scanning tests were performed on the mudrock specimen soaked for different time. The space-time evolution characteristics of water-induced cracks inside mudrock， including the original fracturing effect， netty extension behavior， spatial nonuniformity distribution and active period of reaction， were exposed dynamically by CTS. The water-weakening process of the mudrock meso-structure can be divided into the following steps: firstly， inherent micro fractures provide the initial path for water to invade into unloaded mudrock; then the incursive water induces the volume increase of clay minerals and ion solution of carbonate through physical and chemical reactions; finally， the adverse mechanical impact derived from the volume expansion and solution of carbonate leads to the propagation and connection of cracks. References | Related Articles | Metrics

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Parameters and Characteristics of Self-Priming Abrasive Jet Nozzle for Cutting Coal Seam ZHANG Xin-wei，LU Yi-yu ，TANG Ji-ren，ZHOU Zhe 2015, 36 (10):  1466-1471.  DOI: 10.3969/j.issn.1005-3026.2015.10.022 Abstract ( 637 )   HTML   PDF (784KB) ( 580 )   High-pressure water jet becomes invalid in cutting hard coal seam， and abrasive jet cutting technology is difficult to achieve continuous addition of abrasives. In order to overcome these difficulties， a self-priming abrasive jet nozzle using the forward and backward nozzle structure was designed on the basis of the principle of ejector. This nozzle can achieve continuous inhalation of coal particles produced by slotting to form abrasive jet， with the slotted capacity improved. By simulating the two-phase liquid-solid interaction， it was found that coal particles in the nozzle experience three acceleration stages at intake， mixing chamber and nozzle， respectively. According to the volume of particles and the final velocity of the particles， the most optimal nozzle structure was obtained: the front nozzle diameter is 3mm， the back nozzle diameter is 5mm， and the length of the back nozzle is 15mm. The comparison of the experiments results showed that the slotting efficiency of the self-priming abrasive nozzle was improved significantly compared to that of the traditional cutting seam. References | Related Articles | Metrics

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Application of K-S Test in Structural Homogeneity Dividing of Fractured Rock Mass RUAN Yun-kai， CHEN Jian-ping， CAO Cen， YAN Huan 2015, 36 (10):  1471-1475.  DOI: 10.3969/j.issn.1005-3026.2015.10.023 Abstract ( 583 )   HTML   PDF (514KB) ( 641 )   Based on K-S test， a new method was proposed to identify statistically homogeneous regions in a fractured rock mass by considering trace length of joints. The cumulative frequencies of each attribute of contrasting samples， the K-S statistical quantity and the K-S critical values were calculated to validate the significant difference between the comparative samples， based on which， the structural homogeneity of fractured rock mass was divided. This method was used to analyze the effect of the trace length on statistically homogeneity division in the fractured rock mass at two adjacent adits in different weathered zone at the Maji dam site on the left bank of the Nu River in Yunnan province. It was calculated that the rock mass at two adjacent adits shows statistical similarity in the lower limit of weak weathering， slightly weathering and fresh rock zones，and can be divided into statistically homogeneous areas， however it shows no statistical similarity in the upper limit of weak weathering. The rock mass at a single adit shows no statistical similarity in the every division of weathering. In addition， the proposed method can be applied to identify the dividing of joint samples with small sizes. References | Related Articles | Metrics

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Fire Resistance of Simple Supported Reinforced Concrete Beams Under High Temperature DING Fa-xing， YAO Fei， LI Zhe， YU Zhi-wu 2015, 36 (10):  1476-1481.  DOI: 10.3969/j.issn.1005-3026.2015.10.024 Abstract ( 583 )   HTML   PDF (931KB) ( 836 )   The experiment of two reinforced concrete beams under high temperatures were conducted. A reasonable material thermal performance and thermal-mechanical coupled constitutive relation were adopted in the 3D finite element model by ABAQUS to analyze the performance of reinforced concrete beams. Temperature field and deformation results agree well with the test results. Based on experiment verifications， the effects of protective layer thickness and the load level on the fire resistance of concrete beams were studied by using finite element parametric analysis. Results showed that the thicker the concrete cover is， the slower the temperature rise of tensile reinforcement is， and the smaller the deflection of speciment is， which means that the fire resistance of reinforced concrete beam is longer. Correspondingly， the fire resistance gets shorter when load level is increased. References | Related Articles | Metrics

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Roasting Reduction and Its Kinetics of Low-Grade Pyrolusite by Biomass Char FENG Ya-li， ZHANG Shi-yuan， LI Hao-ran， ZHOU Yu-zhao 2015, 36 (10):  1482-1486.  DOI: 10.3969/j.issn.1005-3026.2015.10.025 Abstract ( 554 )   HTML   PDF (530KB) ( 647 )   Roasting reduction contrast experiments of low-grade pyrolusite were performed by using biomass char and activated carbon as the reductant in a tube furnace. The effects of roasting temperature， roasting time and the dosage of biomass char on manganese reduction efficiency of pyrolusite were studied， and X-ray diffraction analysis was carried out for the roasting products. The results indicated that biomass char is obviously better than activated carbon in roasting time and manganese reduction efficiency.Roasting reduction of pyrolusite undergoes the process of MnO2→Mn2O3→Mn3O4→MnO. Manganese reduction efficiency greater than 98% was achieved when roasting temperature is 800℃， roasting time is 50min and the dosage of biomass char is 10%. Based on the results， the reduction kinetics equation was derived， and it is confirmed that the reduction process is controlled by interface chemical reaction， and the apparent activation energy is about 43.896kJ·mol-1. References | Related Articles | Metrics

Mechanical Engineering

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Nonlinear Dynamic Characteristics of Air-Leg Rock Drill Piston HUANG Jing， ZHU Li-sha， ZHANG Yi-min 2015, 36 (10):  1487-1490.  DOI: 10.3969/j.issn.1005-3026.2015.10.026 Abstract ( 517 )   HTML   PDF (566KB) ( 624 )   Taking a piston of air-leg rock drill as the research object， a finite element analysis model of the impact system including the piston and drill rod was set up based on the actual conditions. Its nonlinear dynamic characteristics were analyzed using the ANSYS/LS-DYNA software. Therefore， the stresses and strains of the impact system at different time were obtained. The results showed that there are minor deviations between the calculated and experimental results. The maximum stress， which is greater than the fatigue limit and less than the yield limit， appears at the impacting face. The spline root of the piston with strong stress is also a weak link. The failure form of the piston is the contact fatigue of the end face or fatigue fractures of the spline root， which coincides well with the actual situation and provides a scientific basis for reliability design of the piston. References | Related Articles | Metrics

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Effect of Grinding Fluid Parameters on Microstructure Damage of Grinding Hardening Surface ZHANG Xiu-ming， XIU Shi-chao， WANG Yu-shi 2015, 36 (10):  1491-1495.  DOI: 10.3969/j.issn.1005-3026.2015.10.027 Abstract ( 563 )   HTML   PDF (714KB) ( 693 )   Aiming at the grinding fluids influence on grinding forces and grinding temperature field in the grinding hardening process， a simulation model of non-quenched and tempered 45 steel was established to analyze the influence of different grinding fluid parameters on the grinding workpiece surface hardness and residual stress. At last， the workpiece surface hardness and its surface integrity after plane grinding hardening experiment by changing the grinding fluid parameters were studied. The results showed that the surface microstructure damage has a closest connection to the grinding depth. Adding a certain amount of grinding fluid can effectively reduce the surface microstructure damage， but it seriously weakens the effect of using grinding heat to strengthen the workpiece surface. References | Related Articles | Metrics

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Temperature Field of Hot Rolling Work-Roll for Aluminum Sheet GAO Shan-feng， XI An-min， LIU Hong-fei， WANG Chao 2015, 36 (10):  1496-1500.  DOI: 10.3969/j.issn.1005-3026.2015.10.028 Abstract ( 656 )   HTML   PDF (873KB) ( 676 )   Upon the different heat transfer conditions experienced in a revolution， the coordinates of the circumferential direction of work-roll were converted to time coordinate， and the corresponding boundary conditions were added. These methods can make the results close to the thermal behavior of actual rolling. After analyzing the temperature field of work-roll， it shows that the temperature in the depth of 10~ 19mm increases slowly， while keeps constant in the depth over 19mm， as well as nearly axial symmetrical distribution in the depth of 2~ 10mm. It can quickly reach dynamic stability after drastically changing in less than 2mm depth namely about 1% area. Rolling speed of the work-roll has little effect on the temperature in the depth of greater than 2mm. When the rolling rhythm is less than 0.5， reducing it will have little influence on the temperature of the work-roll. References | Related Articles | Metrics

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Pull System Design Based on Value Stream Mapping for ETO Products ZHOU Jian， XIAO Hao-feng， WANG Xiao-hu 2015, 36 (10):  1501-1505.  DOI: 10.3969/j.issn.1005-3026.2015.10.029 Abstract ( 639 )   HTML   PDF (822KB) ( 766 )   The features of ETO products are multi-species but single production for each contract， how to design pull system， improve throughput and control WIP， response to customers’ demand quickly are big problems. To study the pull system which is designed for products of this kind， a HVAC manufacturing company was taken as the case since it is a typical ETO product， and the VSM was used to analyze the production system and critical business process， and the Kanban and Conwip were combined to build pull system. The production process and critical parts procurement process were simulated with Arena， and objective function was constituted with chosen output indexes. The parameters of the system were optimized with OptQuest under different weights. The overall performance of the systeme improves 15.5%~30.5%， and the parameters of pull system are steady. The results showed that the designed pull system is feasible and effective. References | Related Articles | Metrics

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Scheduling Multiple Orders per Job with Various Constraints ZHOU Bing-hai， WANG Teng， FANG Teng 2015, 36 (10):  1506-1511.  DOI: 10.3969/j.issn.1005-3026.2015.10.030 Abstract ( 482 )   HTML   PDF (451KB) ( 598 )   Taking a comprehensive consideration of the characteristics of multiple product types， the past-sequence-dependent (p-s-d) setup time and the deterioration effects constraints in processes of wafer fabrication， with an objective function of minimizing total weighted earliness-tardiness penalties cost， a mathematical programming model of scheduling multiple orders per job (MOJ) in a single machine was built. On this basis， the decision-making variables were separated， and a modified genetic algorithm-ant colony optimization (MGA-ACO) algorithm adopting two-level encoding mechanism was put forward. Genetic algorithm was converged to the process of dynamic and adaptive ant colony iterations. To improve the algorithm convergence performance， a modified rule of apparent tardiness cost with setups (ATCS) was applied. Finally， the simulation results indicated that the developed algorithm is valid and feasible. References | Related Articles | Metrics

Management Science

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Pricing Strategy of Multi-channel Supply Chain with Retailer’s Capital Constraint LI Kai，CHEN Wei-hua 2015, 36 (10):  1511-1515.  DOI: 10.3969/j.issn.1005-3026.2015.10.031 Abstract ( 662 )   HTML   PDF (519KB) ( 772 )   A pricing strategy of multi-channels supply chain model was studied with many retailers and capital constraint. According to the difference of retailer’s capital condition， the relationship between supply chain upstream and downstream was analyzed by using the Stackelberg and Bertrand game theory. The pricing decision-making strategies of the manufacturer and the retailers were given， and the supply chain member’s performances were analyzed under the different pricing decision-making strategies.The results showed that the manufacturer can get the highest profit and the retailer can get a lower profit under sufficient funds condition.Comparing with the loan-payment strategy， the manufacturer and the retailers can both gain more profit by the deferred-payment strategy under insufficient funds condition. The deferred-payment strategy is the best decision-making for the supply chain channel under capital constraint. References | Related Articles | Metrics

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Topology Property and Industry Dominance in Weighted Network for China’s Stock Market JIN Xiu， JIANG Chao， MENG Ting-ting，ZHUANG Xiao-wei 2015, 36 (10):  1516-1520.  DOI: 10.3969/j.issn.1005-3026.2015.10.032 Abstract ( 718 )   HTML   PDF (647KB) ( 702 )   The minimum spanning tree was constructed by using the clustering algorithm， which was used to study the topological structure of various industries. Based on the weighted network model， a dynamic weighted network model considering the characteristic of time variation was developed. Taking the SSE 180 index as sample， the market dominance of the Chinese stock market was studied. The empirical results showed that the Chinese stock market has notable aggregation， and the same industry stocks have similar characteristics. The finance/insurance and the manufacturing industry are relatively more active， and the prices of others are more susceptible to these two industries. The leading industry in the stock market will change with the time， and the emerging industry gradually dominates the overall industry. References | Related Articles | Metrics