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15 January 2018, Volume 39 Issue 1 Previous Issue    Next Issue
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Information & Control

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Parameter Identification of Multivariate Hammerstein-Wiener Model BAI Jing ， MAO Zhi-zhong， PU Tie-cheng 2018, 39 (1):  6-10.  DOI: 10.12068/j.issn.1005-3026.2018.01.002 Abstract ( 1594 )   HTML   PDF (529KB) ( 1324 )   In order to break the limited condition that the output nonlinear blocks are reversible in existing Hammerstein-Wiener model parameter identification methods， a new parameter identification method of multivariate Hammerstein-Wiener model was proposed based on separable nonlinear least square algorithm. The model was comprised of multiple univariate Hammerstein submodels and one multivariate nonlinear block. First， two parameter sets were identified for output nonlinear block and Hammerstein submodels using Levenberg-Marquardt algorithm under the minimum output error criterion. Second， parameters of input nonlinear block and middle linear block were identified by singular value decomposition (SVD) of tensor product from Hammerstein submodels. Then， the identification convergence was theoretically analyzed. Finally， simulation results showed the effectiveness of the proposed method. References | Related Articles | Metrics

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Micro-force Sensor Based on Photonic Crystal Micro-cavity and Fiber Loop Ring-Down QIAN Xiao-long， ZHANG Ya-nan 2018, 39 (1):  11-14.  DOI: 10.12068/j.issn.1005-3026.2018.01.003 Abstract ( 650 )   HTML   PDF (750KB) ( 721 )   A high-sensitive micro-force measurement method based on photonic crystal micro-cavity was proposed. Firstly， an M-typed beam was proposed as the sensing head， thus the resonance wavelength drift of the micro-cavity will only be affected by holes refractive index of photonic crystal micro-cavity when force was applied on this system， which could greatly improve the linearity and measurement range of sensor. Then， the structure of photonic crystal micro-cavity with micro-ring structure was optimized， and the quality factor of 7100 was obtained. Finally， the wavelength demodulation system based on fiber loop ring-down was built， with proper selection and design of experimental apparatuses， and the wavelength demodulation sensitivity could reach to 90μs/nm. Therefore， it was demonstrated that the measurement sensitivity of 194.616μs/μN could be obtained by using our proposed micro-force measurement system. References | Related Articles | Metrics

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Intelligent Cigarette Sensory Evaluation Method Based on OVO Decomposition Strategy ZHANG Zhong-liang， LUO Xing-gang， TANG Jian-guo ， TANG Jia-fu 2018, 39 (1):  15-20.  DOI: 10.12068/j.issn.1005-3026.2018.01.004 Abstract ( 737 )   HTML   PDF (377KB) ( 717 )   Intelligent cigarette sensory evaluation system involves multi-class classification problems. The one-versus-one (OVO) decomposition strategy was employed to divide the multi-class classification problem into several easier-to-solve binary sub-problems. Then binary classifiers were established for these sub-problems. Finally， an aggregation strategy was adopted to combine the binary classifiers to be a multi-class classifier. In addition， dynamic classifier selection for OVO strategy (DCS-OVO) and distance-based relative competence weighting for OVO strategy (DRCW-OVO) were used to reduce the negative effect of the non-competent classifiers. In order to verify the effectiveness of the employed method in intelligent cigarette sensory evaluation， the experimental comparison by using the dataset from a Chinese tobacco company was carried out. The results indicate that the OVO decomposition strategy outperforms the classical methodology in intelligent cigarette sensory evaluation. References | Related Articles | Metrics

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Robust Program Model of Human Resource Management for Staffing Call Centers GONG Jun， JIA Qian-qian， ZHANG Jia-sheng， YU Miao 2018, 39 (1):  20-25.  DOI: 10.12068/j.issn.1005-3026.2018.01.005 Abstract ( 738 )   HTML   PDF (511KB) ( 807 )   Considering the problem that the arrival rates of call centers are uncertain， a discrete fluid model was built based on queuing theory， and the human resource allocation problem of staffing call centers was solved with the robustness. The set of uncertain arrival rate was formulated by using interval data， and by adjusting the robust optimization method of adjustable robust parameters to solve the staffing problem， the relationship between robust optimization model and deterministic optimization model was analyzed. Numerical experiments show that， using the robust optimization method with adjustable robust parameters can reduce the impact of random arrival rates on call centers; with the increasing of arrival rates， the corresponding optimal robust parameter will be increased， and the model is more conservative. References | Related Articles | Metrics

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Research and Implementation of Snoring Head Posture Detecting System Based on Sound Source Localization Technology KANG Yan， NING Guo-chen 2018, 39 (1):  26-31.  DOI: 10.12068/j.issn.1005-3026.2018.01.006 Abstract ( 627 )   HTML   PDF (722KB) ( 879 )   Sound source localization technology in the application of snoring detecting was studied， mainly including the aspects of acoustic characteristics of snoring as well as sound source localization technology principle and was used to detect the head posture of snoring human. The generalized cross-correlation(GCC) function algorithm was used to calculate relative time-delaying estimation of snoring signals from mulita-channel sound acquisition system and sound position was obtained based on the relative delay information. Face orientation and head location information were combined to deduce the current head posture. The head posture detecting system contained high speed signal acquisition which was compiled by using DAQ.Besides，algorithm and signal processing was compiled by Labview. In the experiment， the subject simulated snoring under the detecting of system and the accuracy of the results is up to 80%. References | Related Articles | Metrics

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Spectrum Sensing Algorithm Based on Dynamic Group Sparsity Reconstruction LIU Fu-lai， LIU Lei， DU Rui-yan， ZHANG Miao 2018, 39 (1):  31-34.  DOI: 10.12068/j.issn.1005-3026.2018.01.007 Abstract ( 707 )   HTML   PDF (490KB) ( 693 )   To solve the problem of wideband spectrum sensing in cognitive radio networks， a spectrum sensing algorithm based on the spectrum structure of primary user signals was proposed， which is called DGS-SS algorithm. Firstly， compressed sensing theory was applied to signal acquisition to achieve a sub-Nyquist rate. Secondly， the group sparsity structure of primary user spectrum was used to modify the spectrum and residual support set during the reconstruction process， which can speed up the convergence and improve the accuracy of the reconstruction of primary user spectrum. Finally， effective detection of spectrum holes was given by the reconstructed signal spectrum. Simulation results show that the proposed algorithm can accurately reconstruct the spectrum at low compression ratio and have stronger robustness to noise variation， which makes the spectrum sensing performance significantly improved. References | Related Articles | Metrics

Materials & Metallurgy

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Effect of Mg， Ca Addition on Microstructure and Properties of Biodegradable Zn Alloy WANG Li-qing， SUN Shi-neng， REN Yu-ping， QIN Gao-wu 2018, 39 (1):  35-39.  DOI: 10.12068/j.issn.1005-3026.2018.01.008 Abstract ( 822 )   HTML   PDF (2353KB) ( 824 )   Pure Zn and Zn-0.2Mg-xCa (x=0， 0.06， 0.15 and 0.3，mass fraction) alloys were prepared by indirect hot extrusion. The microstructure， mechanical properties and in vitro degradation rate of extruded Zn-based alloys were investigated by X-ray diffraction， scanning electron microscopy， optical microscope， tensile test and immersion test. The results showed that pure Zn consisted of equiaxed grains with the size of 100μm and Zn-0.2Mg-xCa alloys were composed of refined grains with the size of 15~20μm and the second phases of Mg2Zn11 and CaZn13. With increasing Ca addition， the amount of CaZn13 increased and the size of CaZn13 reached 15~50μm when the Ca mass fraction was over 0.15%. The yield strength and elongation of pure Zn was 64MPa and 14%， respectively. With increasing Ca addition， the yield strength of Zn-0.2Mg-xCa increased from 180MPa to 200MPa， while the elongation decreased from 18% to 6%. The degradation rate of Zn and Zn-0.2Mg-xCa kept between 0.05~0.15mm·a-1 and decreased with Ca addition. References | Related Articles | Metrics

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Effect of Normalizing on Microstructure and Properties of High Chromium Martensitic Heat Resistant Steels CUI Chen-shuo ， GAO Xiu-hua， SU Guan-qiao ， QUAN Xiu 2018, 39 (1):  40-44.  DOI: 10.12068/j.issn.1005-3026.2018.01.009 Abstract ( 803 )   HTML   PDF (2636KB) ( 965 )   Effect of normalizing heat treatment on microstructure， mechanical properties and fracture mechanism of high Cr martensitic heat resistant steel was investigated by optical microscopy， transmission electron microscopy (TEM) and scanning electron microscope (SEM) analysis. The results show that after normalizing at 900~970℃， grain size is very small which is less than 10μm. After normalizing at 1060~1200℃， grain size increases rapidly which is about 33μm at 1060℃. After normalizing at 1060℃ for 2h and tempering at 760℃ for 3h， the excellent mechanical property can be achieved where the tensile yield strength at room temperature and high temperature at 600℃ is about 535MPa and 380MPa， respectively; while a longer normalizing time at 1060℃ has no obvious effect on mechanical property. Moreover， after normalizing at 1060℃ for 2h and tempering at 760℃ for 3h， mechanical properties can also be improved effectively by the fine grains of the tempered martensite， the precipitate of M23C6with its size of 200 ~ 300nm at the grain boundaries and the MX dispersion with its size of 5~50nm inside grains. References | Related Articles | Metrics

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Microstructure and Properties of Biomedical Zn-5Al Alloy ZU Guo-yin， LIU Ying， SHI Jian-chao， MU Yong-liang 2018, 39 (1):  45-49.  DOI: 10.12068/j.issn.1005-3026.2018.01.010 Abstract ( 661 )   HTML   PDF (4551KB) ( 792 )   The phase selection and microstructural evolution of biodegradable biomedical Zn-5Al alloy were studied. The microstructure of as casting， after homogenization treatment and the rolled Zn-5Al alloy was characterized， respectively and the phase compositions of the Zn-5Al alloy was analyzed.Then the mechanical properties of the rolled Zn-5Al alloy were tested. The results showed that the phase compositions of the as casting Zn-5Al alloy and after homogenization treatment were mainly composed by the η-Zn phase and α-Al phase. The interlamellar spacing of the eutectic structure in the as casting Zn-5Al alloy was about 300nm.The eutectoid reaction occurred during the homogenization treatment and the α-Al phase of the Zn-5Al alloy was changed from the original strip shape to spherical eutectic structure after homogenization treatment. After rolling of 85% for a total deformation rate， the yield and tensile strength of the Zn-5Al alloy were 98MPa and 130MPa， respectively， and its fracture elongation reached 74%. References | Related Articles | Metrics

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Analysis of Mixed-Grain Microstructure of P91 Thick-Walled Steel Pipes NING Fang-kun， JIA Wei-tao， ZHU Fu-xian， WANG Ping 2018, 39 (1):  50-55.  DOI: 10.12068/j.issn.1005-3026.2018.01.011 Abstract ( 755 )   HTML   PDF (9886KB) ( 1004 )   A mixed-grain phenomenon was observed in the P91 thick-walled steel pipes， which would reduce the high-temperature properties of the pipes. Heat treatment process， the category of ingot and the microstructural evolution during hot rolling were analyzed. The results indicated that the difference of the categories for the P91 forging ingot and continuous casting ingot did not lead to microstructure difference. The pipes appeared obvious mixed-grain microstructure after hot rolling and the optimal microstructure could not be achieved only through the conventional normalizing and tempering treatment. The pipes’ microstructure uniformity can be optimized effectively by transforming from non-equilibrium microstructure to equilibrium one and rational heat treating process. The mixed-grain microstructure was not discovered in the steel pipes under the hot rolling process with the same processing parameters. However， abnormal grains growth was observed in the pipes after Pilger rolling.Therefore， the Pilger rolling process was the stage of mixed-grain initiation and improvement of microstructure uniformity. References | Related Articles | Metrics

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Effect of Screw Structure on Burdens Moving Behavior in COREX Shaft Furnace with DEM Simulation ZHANG Li-juan， QIU Zi-long， LUO Zhi-guo， ZOU Zong-shu 2018, 39 (1):  55-60.  DOI: 10.12068/j.issn.1005-3026.2018.01.012 Abstract ( 605 )   HTML   PDF (1368KB) ( 745 )   A COREX-3000 shaft furnace model was established based on discrete element method to compare the drawdown uniformity coefficient， drawdown pattern and distribution of descending velocity between Baosteel screw and the newly designed screw by means of simulating. The results show that the drawdown uniformity coefficients of Baosteel screw from pitch 1 to pitch 5 are small and the peak 0.36 appears at pitch 4. However， the drawdown uniformity coefficients of the newly designed screw are close to 1 in all the burden drawdown area. From the macroscopic aspect， the drawdown patterns of the new screw along the whole height of shaft furnace are more uniform than that of Baosteel screw. Below the gas slots， the distribution of descending velocity along the radius of the shaft furnace with the new screw are more uniform than that with Baosteel screw. Above the gas slots， the effect of screw structure on burden descending velocity is small， and the drawdown patterns is more like plug flow. References | Related Articles | Metrics

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Analysis of Bubbles Motion Behavior and Influence Factors in Continuous Casting Mold ZHANG Tao， NIE Hai-qi， LUO Zhi-guo， ZOU Zong-shu 2018, 39 (1):  61-65.  DOI: 10.12068/j.issn.1005-3026.2018.01.013 Abstract ( 689 )   HTML   PDF (1512KB) ( 835 )   An original mathematical model was developed to study the behavior of bubbles and influence factors in continuous casting mold. The interactions between bubbles were considered in the model， including bounce off， coalescence and breakup. The effects of casting speed and nozzle immersion depth on bubbles behavior were investigated， including region of bubble dispersion， gas volume fraction and bubble mean diameter. The results showed that the initial bubbles can merge into a large bubble in the nozzle.With increasing the nozzle immersion depth， the region of bubble dispersion and gas volume fraction increase， but the average diameter of bubbles decreases under the same casting speed. With increasing casting speed， the law is same under the same nozzle immersion depth. Casting speed has greater influence than nozzle immersion depth on bubble diameter. References | Related Articles | Metrics

Mechanical Engineering

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Trajectory Tracking Control for a Quadrotor UAV Based on Improved Backstepping ZHOU Lai-hong， DOU Jing-xin， ZHANG Ju-qian， WEN Bang-chun 2018, 39 (1):  66-70.  DOI: 10.12068/j.issn.1005-3026.2018.01.014 Abstract ( 1387 )   HTML   PDF (675KB) ( 1467 )   Quadrotor unmanned aerial vehicle (UAV) is an underactuated， strongly coupled and highly unstable nonlinear system. The robustness and ability of anti-jamming for UAV system are the key problems of flight control. In order to restrain constant disturbance and variable disturbance during UAV flight， a novel control method named integral saturation backstepping control (ISBC) was proposed by introducing both the error integral and saturation function into classical backstepping control (CBC). The system stability was verified by the Lyapunov stability theorem. The simulation experiment of trajectory tracking was carried out using MATLAB/SIMULINK. Results of simulation experiment indicate that the quadrotor UAV system with ISBC control strategy performs better for anti-jamming and superior robustness than that with CBC control strategy. References | Related Articles | Metrics

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Contact Performance Evaluation and Parameter Sensitivity Analysis for Aerospace Electrical Connector LI Cui-ling， DAI Peng-fei， YANG Qiang， ZHANG Meng-jun 2018, 39 (1):  71-75.  DOI: 10.12068/j.issn.1005-3026.2018.01.015 Abstract ( 680 )   HTML   PDF (4304KB) ( 816 )   The contact calculation model for the cylindrical double groove electric connector， a significant component in aerospace equipment， was established. The mathematical relationship between the contact friction force and the insertion amount of pins was derived. The parameterized modeling for 38999 series 22# general contact elements was performed using SOLIDWORKS， and the contact performance was analyzed using ABAQUS finite element analysis software. It is obtained that the optimum closing amount of the socket end， with the insertion force as an assessment index， is 0.66mm. Sensitivity of the socket structure parameters was analyzed， and its structural optimization was determined based on the fuzzy comprehensive evaluation method. The optimum contact performance is obtained when the length of the socket reed is 3mm， the width of the socket slot is 0.43mm and the closing amount of the socket end is 0.67mm. References | Related Articles | Metrics

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Simulation and Experimental Study on the Milling Force of Aluminum Alloy 6061 in Micro-milling CAI Ming， GONG Ya-dong， YU Ning， GAO Qi 2018, 39 (1):  76-81.  DOI: 10.12068/j.issn.1005-3026.2018.01.016 Abstract ( 1068 )   HTML   PDF (1678KB) ( 900 )   The finite element simulation and single factor experiment were combined to carry out the research of the influential factors for the milling force of aluminum alloy 6061 in micro-milling. The three-dimensional model of the tool and workpiece was established and assembled， and the mesh was also divided. The micro-milling process of aluminum alloy 6061 material was simulated， and the influence of milling speed and milling depth on the milling force was obtained by the finite element simulation. The single factor experimental study was also conducted. The results showed that: with the increase of spindle speed， the milling force increases first and then decreases， whose turning point is 24000r/min; with the increase of milling depth， the milling force increases first and then decreases and increases， whose turning point is 10μm and 12μm; with the increase of feed rate， the milling force also increases. The optimized parameter combination of aluminum alloy 6061 material in micro-milling is as follows: the spindle speed is 48000r/min， the milling depth is 5μm， and the feed rate is 20μm/s. References | Related Articles | Metrics

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Micro-grinding Temperature Simulation for Nickel-Based Single Crystal Superalloy GONG Ya-dong， ZHOU Jun， ZHOU Yun-guang， HUANG Xiong-jun 2018, 39 (1):  82-86.  DOI: 10.12068/j.issn.1005-3026.2018.01.017 Abstract ( 674 )   HTML   PDF (2741KB) ( 866 )   According to the condition that rare studies are working on micro-grinding temperature field for the nickel-based single crystal superalloy which has strong anisotropy ，three dimensional simulation model based on the Hill model was established by ALE method for temperature simulation in micro-grinding process for nickel-based single crystal superalloy. The distribution and variation of temperature fields in the micro-grinding process were discussed， and the influences of grinding depth， grain velocity and different crystal face (100)，(110) and (111) on the micro-grinding temperature were analyzed. The simulation results showed that the high temperature zone happens in the semi ellipse region between the front surface of abrasive and the workpiece. The grinding temperature increases with the grinding depth and grinding speed. During the micro-grinding of single crystal materials， the temperature of (111) crystal plane is the highest， and the (110) is the second， and the (100) is the least. References | Related Articles | Metrics

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Natural Characteristics of Fiber-Reinforced Cantilever Composite Thin Plate Under Thermal Vibration Environment LI Hui， WU Huai-shuai， WEI Sha， LI Zheng-ze 2018, 39 (1):  87-92.  DOI: 10.12068/j.issn.1005-3026.2018.01.018 Abstract ( 652 )   HTML   PDF (2652KB) ( 791 )   The equation of motion for fiber-reinforced composite cantilever thin plate was derived based on Hamilton’s principle， and its natural frequencies were calculated by two-dimension beam function method. Then， the Matlab calculating program was written， and the specific analysis procedures of natural characteristics of fiber-reinforced cantilever thin plate under thermal vibration environment were also proposed. Finally， TC500 fiber/epoxy composite plate was taken as a study object， and its frequency and shape results are measured based on the established test system of natural characteristics of the cantilever composite plate under thermal vibration environment. It was found by comparison that the calculated frequencies under thermal vibration environment have a good agreement with the experimental results， and the related errors are within the range of 15 %. Besides， modal shapes are also consistent with the measured shape results， thus the effectiveness of the above method is verified. References | Related Articles | Metrics

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Design and Control of a Novel Variable Stiffness Soft Arm XIANG Chao-qun， ZHANG Ying， GUO Shao-fei， HAO Li-na 2018, 39 (1):  93-97.  DOI: 10.12068/j.issn.1005-3026.2018.01.019 Abstract ( 998 )   HTML   PDF (1206KB) ( 1158 )   Soft robot arms has unique capabilities in reconfigurability， adaptability， flexibility and dexterity. In particular， pneumatic soft robotic systems have advantages such as light weight， high power to weight ratio， and having inherent safety in physical human-robot interaction. A novel design of a soft robotic arm consist of both contractile and extensor pneumatic artificial muscle (PAM) was presented. Kinematic model of this arm was established， and the workspace was analyzed using MATLAB. Experiment setup was established， and motion control experiment of the arm was carried out. Experimental results showed that steady state mean error of tracking step signal is 0.0028rad(0.16°)， rise time is less than 2s; mean error of tracking sine signal is 0.0159 rad(0.911°)， which means this arm has good controllability. References | Related Articles | Metrics

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Combustion Characteristics Analysis of the Alcohol and Diesel Blends ZHOU Nan， WU Han 2018, 39 (1):  97-101.  DOI: 10.12068/j.issn.1005-3026.2018.01.020 Abstract ( 823 )   HTML   PDF (3851KB) ( 823 )   The combustion characteristics of the alcohol (acetone - butanol - ethanol， ABE) and diesel fuel mixture was studied in the constant volume chamber with a window on the top. A premixed gas mixture containing C2H2， N2， and air was burned in the constant volume chamber to generate a high temperature and high pressure environment that simulated the typical diesel engine in-cylinder top dead centre (TDC) condition. The combustion process was recorded through the top window using a high speed camera (Phantom V7.1) located above the chamber. The results and discussions were based on the data above. It is found that at low ambient temperature and low ambient oxygen， the mixture presented extremely low soot luminosity with better combustion efficiency comparing to pure diesel. The high latent heat of vaporization of the alcohol blends contributes to the reduction of the adiabatic flame temperature and the amount of nitrogen oxides suggesting that ABE solution， an intermediate product during ABE fermentation， is a very promising alternative fuel to be directly used in diesel engines especially under low temperature combustion (LTC) conditions. References | Related Articles | Metrics

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Investigation on Driver Fatigue Testing Based on the Combination of Cervical-Lumbar EMG and EEG WANG Lin ， HUA Cheng-cheng， JIANG Xin， WANG Hong 2018, 39 (1):  102-107.  DOI: 10.12068/j.issn.1005-3026.2018.01.021 Abstract ( 761 )   HTML   PDF (994KB) ( 1130 )   In order to effectively test driver fatigue， the surface electromyography (EMG) and electroencephalogram (EEG) were collected in driving processes， and the characteristic parameters were extracted and analyzed combined with biomechanics. The experimental results indicated that the sample entropy (SampEn) and complexity of EMG and EEG gradually decrease with the driving time expends. These characteristic parameters can be reasonably combined by using the principal component analysis. Based on the multiple regression theory， the characteristic parameters at different positions of the body are reasonably combined， and a mathematical model to evaluate fatigued driving is built. The accuracy of the model is up to 95% by the state validation. References | Related Articles | Metrics

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Vibration Characteristics for the Rocker Arm of Shearer with Gear Meshing Excitation ZHANG Rui， ZHANG Yi-min， ZHU Li-sha， ZHAO Chun-yu 2018, 39 (1):  108-112.  DOI: 10.12068/j.issn.1005-3026.2018.01.022 Abstract ( 739 )   HTML   PDF (1064KB) ( 815 )   Experimental research was carried out to study the meshing frequency coupling laws of gear system and vibration characteristics of the rocker arm shell under the gear meshing excitation. According to the gear parameters， the meshing frequency of the system was calculated and the harmonic frequency components were obtained. Based on the finite element model and experimental modal analysis， the inherent characteristics of the rocker arm shell was obtained. Through the rocker arm dynamic characteristics experiment， the vibration accelerations were obtained. Time domain and frequency domain analysis were carried out to get the transmission system frequency coupling rules. Results show that the impact of starting is about 2 times of that of heavy load. The vibration peak occurs on the planetary transmission in steady operation. The main vibration modes of rocker arm are the third and the fifth stages. The joint of planetary and idler has the strongest coupling frequency and the main form of coupling is the combination of characteristic frequencies. Frequency coupling is one of the main reasons that lead to resonance of rocker arm. References | Related Articles | Metrics

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Microstructure and Mechanical Properties of Crack Repairing Zone of Aluminum Alloy Through Friction Stir REN Jun-gang， XIE Li-yang， WANG Lei， ZHANG Zhan-chang 2018, 39 (1):  112-117.  DOI: 10.12068/j.issn.1005-3026.2018.01.023 Abstract ( 730 )   HTML   PDF (3515KB) ( 772 )   Aviation aluminum alloy 2A12 containing the prefabricated 0.8mm deep and 0.5mm horizontal cracks was repaired by the friction stir method， and the microstructure evolution and mechanical properties of the healing zone were observed and analyzed in details. The results showed that the crack repairing is realized in the reasonable healing process， and the tensile strength Rm and the yield strength ReL can reach 90.1% and 92.2% of the base metal. The healing zone consists of three different evolution zones， and in the core zone the cracks are repaired by grain fragmentation， growth and recrystallization. The structural softened zone consists of the thermo-mechanically affected zone with obvious plastic deformation and the heat affected zone with obvious grain growth. The surface hardness is similar to that of the upper cross section with the upper section being harder than that of the lower section. The healing core zone consists of many small angle crystals with dislocated lines inside and tiny strengthening phases around. References | Related Articles | Metrics

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Variable Speed Cutting Control of Shearer Based on Cutting Performance Optimization LIU Yong-gang， HOU Li-liang， QIN Da-tong， YAN Zhong-liang 2018, 39 (1):  118-123.  DOI: 10.12068/j.issn.1005-3026.2018.01.024 Abstract ( 708 )   HTML   PDF (804KB) ( 757 )   Variable speed cutting of shearer was studied， in order to solve the practical problem that the cutting performance of the drum shearer decreases when changing the hauling speed only. Considering the feasibility and reliability of variable speed cutting， the hardness of the coal seam was divided into several ranges by its cutting impedance. Aiming at the weighted average optimization of lump coal rate， cutting energy consumption rate and productivity， the cutting motion parameters of shearer were optimized. Besides， variaous speed control strategies of conditions caused by cutting impedance change were compared， and the speed control strategies for the best cutting performance of different conditions were obtained. The results provide a good reference for the research of high efficiency variable speed cutting. References | Related Articles | Metrics

Resources & Civil Engineering

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Optimization on Stripping Plan of Outsourced Open-Pit Mines WANG Qing， ZHANG Zhi-tong， GU Xiao-wei， XU Xiao-chuan 2018, 39 (1):  123-127.  DOI: 10.12068/j.issn.1005-3026.2018.01.025 Abstract ( 620 )   HTML   PDF (386KB) ( 868 )   Since the "stripping peak" has a negative effect on mine production， the tactics of equipment update and the optimization on stripping plan of outsourced open-pit mines were studied. Based on the relation between the cost of stripping equipment， the production capacity and the changing of the service age， a dynamic economic life model was established to decide the retire time of a single equipment. Meanwhile， the configuration algorithm steps of a specific equipment was also given out. First， a series of different levels of mine stripping and outsourced stripping boundaries were set to calculate the feasible range of unit cost for the outsourced program， then the outsourced contract price was determined in the feasible range; Finally， based on the contract price， the net present value of the total cost was analyzed to get the optimized outsourced plan. It is proved that the cost of reducing equipment investment by this method is higher than the cost of outsourced rock stripping. References | Related Articles | Metrics

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Ecological Adaptability Evaluation of Warm-Season Herb Plants of Highway Slope LIANG Li， JI Gui-bin， ZHAO Ying 2018, 39 (1):  128-132.  DOI: 10.12068/j.issn.1005-3026.2018.01.026 Abstract ( 630 )   HTML   PDF (423KB) ( 658 )   In order to optimize the selection of suitable vegetation group for the Guanghe highway slope， a combined experiment on the local well-grown herb vegetation was conducted. Through seeding experiment of eight kinds of warm-season herb plants in the local area combined with analytic hierarchy process (AHP)， the ecological adaptability was evaluated. Results indicate that， among the eight kinds of warm-season herb plants， Vetiveria zizanioiaes， Cynodondactylon(Linn.) Pers and Paspalum notatum are the best plants which have better ecological adaptability and slope protection function; Zoysia japonica and Zoysia sinica Hance are the second， and the Zoysia matrella and Pennisetum alopecuroides (L.) Spreng are the worst. Therefore， it is suggested that the warm-season herb plants of Vetiveria zizanioiaes， Cynodondactylon(Linn.) Pers and Paspalum notatum should be chosen as the Guanghe highway slope protective vegetation. The research results provide a theoretical foundation and a technical support for Guangzhou and other subtropical zones. References | Related Articles | Metrics

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Application of Vertical Zone and Combination Ore-Drawing in Inclined Medium-Thick Orebody TAN Bao-hui， REN Feng-yu， HE Rong-xing， ZHANG Zhi-gui 2018, 39 (1):  133-137.  DOI: 10.12068/j.issn.1005-3026.2018.01.027 Abstract ( 643 )   HTML   PDF (901KB) ( 742 )   To solve the problems of poor recovery and high dilution when using the sublevel caving method for inclined medium-thick orebody， a vertical zone and combination ore-drawing scheme was proposed. Three drawing tests were experimentally conducted by 3D physical modeling， in which the complete cutoff grade drawing was used in test (1)， and the combination drawing was used in test (2) and test (3)，respectively. The main difference between test (2) and test (3) lied in that the dilution rate in footwall zone was increased in test (3). The tests results show that in test (1)， the ore recovery rate (η=86.3%) and the corresponding rock dilution rate(ρ=29.5%) is the highest; the recovery rates of the two combination drawing tests are both up to more than 80%， but with a decreased rock dilution rate of about 11.3% (ρ=18.2%) compared with the complete cutoff grade drawing test. The economic evaluation on the three groups of tests show that test (2) is the optimal scheme， whose feasibility and superiority are further verified in the mine. References | Related Articles | Metrics

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TiO2 Photocatalyst Modified by Carbon Quantum Dots and Its Activity in Pollutants Degradation JIANG Ting-ting， SHI Yong， KE Jun， XU Kai-li 2018, 39 (1):  138-142.  DOI: 10.12068/j.issn.1005-3026.2018.01.028 Abstract ( 787 )   HTML   PDF (957KB) ( 1668 )   The nanocomposite photocatalyst TiO2 modified by carbon quantum dots(CQDs) was first prepared by sol-gel method and represented by fluorescence spectra， UV-vis absorption spectra， X-ray diffraction and scanning electron microscope. Then， the photocatalytic activity was investigated by degrading methylene blue(MB) in visible light. Results show that CQDs exhibits an upconversion fluorescence， meanwhile， the visible-light response of TiO2 modified by CQDs was significantly improved. For the TiO2/CQDs obtained by hydrothermal method under 180 ℃ lasting for 6h， when the doping amount is 10 mL， the photocatalytic activity is the highest. The degradation rate of MB comes to 80% after 115 min. The TiO2/CQDs is mainly composed by anatase， whose particles take on a spherical shape with a specific surface area up to 200 m3·g-1. References | Related Articles | Metrics

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Stability Behavior of Channel Columns with Complex Edge Stiffeners and Cap Shaped Stiffeners SONG Bo， WANG Lian-guang， WANG Chun-gang 2018, 39 (1):  143-147.  DOI: 10.12068/j.issn.1005-3026.2018.01.029 Abstract ( 673 )   HTML   PDF (528KB) ( 681 )   In order to further understand the mechanical behavior of the channel columns with complex edge stiffeners and cap shaped stiffeners，the stability of channel columns under axial and eccentric compressive loading was studied by the finite element program called ANSYS. Effects of specimen length， the width to thickness ratio of plate， section types and the eccentric distance on stability，buckling mode and deflection behavior of channel columns with complex edge stiffeners and cap shaped stiffeners were investigated.The results show that under the same condition，the bearing capacity of members with section C2 is 10%~20% larger than that of C1， and the bearing capacity of members with section C3 is 40%~50% larger than that of C1. When it comes to the maximum load， the channel column with cap shaped stiffener on web takes on negative eccentricity， while the channel column with cap shaped stiffener on both web and flange takes on positive eccentricity. References | Related Articles | Metrics

Management Science

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On Multi-phase Information Aggregation Methods Based on Improved Stratified Incentive Control Lines LI Ling-yu， GUO Ya-jun， YI Ping-tao， FENG Xue-li 2018, 39 (1):  148-152.  DOI: 10.12068/j.issn.1005-3026.2018.01.030 Abstract ( 598 )   HTML   PDF (370KB) ( 657 )   Aiming at sequential dynamic comprehensive evaluation， based on multi-phase evaluation information aggregation， three improved stratified incentive methods of multi-phase information aggregation were proposed， i.e.， the aggregation methods of stratifying according to proportion， of stratifying according to one dimensional clustering and of stratifying according to induced variables. Then their stratified models and the processes of information aggregation were analyzed. The improved methods can analyze the alternatives’ implicit information much more thoroughly， and protrude the inspiriting intention of decision makers flexibly. Finally， an example was used to testify the validity of these methods. In practical applications， decision-makers can select appropriate methods according to the needs of specific problems. References | Related Articles | Metrics