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15 June 2019, Volume 40 Issue 6 Previous Issue    Next Issue
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Information & Control

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Adaptive State Feedback Control of Nonlinear Switched Singular Systems YANG Dong-mei， CHEN Jin-ying 2019, 40 (6):  761-765.  DOI: 10.12068/j.issn.1005-3026.2019.06.001 Abstract ( 645 )   HTML   PDF (368KB) ( 813 )   The design of adaptive control for a class of nonlinear singular switched systems satisfying the Lipschitz condition was studied. First， the design of the basic adaptive control of a single input nonlinear singular switching system was studied. The controller was designed to stabilize the system. Then， the adaptive gain and the gain adjustment based on the Lyapunov stability theorem presented by the single input nonlinear singular switching system were used to expand the tracking problem of multi-input singular switching systems and an adaptive control method was designed. Finally， a numerical simulation was performed using Matlab to illustrate the effectiveness of the proposed control method. The proposed controller has a very simple structure and is easy to be applied in practice. References | Related Articles | Metrics

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Effect of Alternating Magnetic Field Exposure on MSEn of Rat ECG LONG Zhe， WANG Xu， YANG Dan 2019, 40 (6):  766-770.  DOI: 10.12068/j.issn.1005-3026.2019.06.002 Abstract ( 583 )   HTML   PDF (656KB) ( 570 )   In order to research the effect of electromagnetic field on the complexity of ECG in organisms， the rats were exposed to 20mT， 50Hz alternating electromagnetic field environment for seven consecutive days. The ECGs of rats which were exposed to the magnetic field for 0， 10， 20 and 30minutes， were collected. The signals were reconstructed using empirical mode decomposition(EMD)， and then the multiscale entropy(MSEn)of each signal was calculated. The results showed that the 20mT， 50Hz alternating magnetic field has a time effect on the multi-scale entropy of rat’s ECG， based on which the effect on the rats can be reduced by cardiac self-regulation. References | Related Articles | Metrics

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Delay Multiply and Sum Beamforming Algorithm for Ultrasound Based on Multi-line Acquisition SU Ting， WANG Ying-ying， ZHANG Shi 2019, 40 (6):  771-776.  DOI: 10.12068/j.issn.1005-3026.2019.06.003 Abstract ( 965 )   HTML   PDF (905KB) ( 1089 )   Based on the high frame rate demand of ultrasound imaging， a beamforming algorithm based on multi-line acquisition delay multiply and sum(MLADMAS) was proposed. This algorithm was based on a method named multi-line acquisition; there are more than one receiving lines from a single transmission line， then the lower complexity DMAS beamforming was used in parallel to obtain several receiving lines simultaneously. The simulated results showed that the frame rate of MLADMAS was 2 times higher than that of DAS with a better image quality. The quantitative indexes FWHM， PSL and CR were improved by 28.49%， 26.29% and 26.06%， respectively. The image quality could be further improved when apodization was applied. References | Related Articles | Metrics

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Web Service Composition Optimization Method Based on Improved Multi-objective Artificial Bee Colony Algorithm SONG Hang， WANG Ya-li， LIU Guo-qi， ZHANG Bin 2019, 40 (6):  777-782.  DOI: 10.12068/j.issn.1005-3026.2019.06.004 Abstract ( 680 )   HTML   PDF (480KB) ( 755 )   To solve the problem of combinatorial diversity and service quality in Web service composition optimization methods， an improvement in artificial bee colony algorithm was proposed. Several methods such as reverse learning operator， elite guidance strategy， and combination mutation strategy were led into the algorithm， by which targeted information could be provided to update individuals. Furthermore， the diversity of service portfolios was enhanced on the premise of ensuring the quality of service portfolios. The experimental results indicated that the refined algorithm has fast convergence speed and good uniformity. Meanwhile， a better optimistic effect was also received for the optimization of Web service composition， and the search accuracy， solution quality and convergence speed were improved as well. References | Related Articles | Metrics

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Feasibility Study on Photovoltaic Electric Vehicle Charging Station for Workplace JI Dong， LYU Ming-song， WANG Yi 2019, 40 (6):  783-788.  DOI: 10.12068/j.issn.1005-3026.2019.06.005 Abstract ( 785 )   HTML   PDF (776KB) ( 858 )   Based on the electric vehicle usage data of factory employees， we analyze the employees’ commute behavior and the distribution of vehicles’ state of charge， and simulate the commute and charging behavior of 100 electric vehicles using Monte Carlo simulation method. A photovoltaic charging station simulation platform is designed to evaluate and analyze the station. Based on the simulation data， the feasibility and system design for photovoltaic EV charging station in the workplace are detailed analyzed and designed by using particle swarm optimization method. The results show that the simulation data can well describe the employees’ travel and charging behavior. The designed photovoltaic charging station system can basically meet the charging demand， so as to promote the sustainable development of the factory and save cost. References | Related Articles | Metrics

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An Algorithm of Trust-based Secure Data Aggregation for Wireless Sensor Networks YE Zheng-wang， WEN Tao， LIU Zhen-yu， FU Chong-guo 2019, 40 (6):  789-794.  DOI: 10.12068/j.issn.1005-3026.2019.06.006 Abstract ( 641 )   HTML   PDF (598KB) ( 663 )   To resist the influence of the malicious attacks and the malfunctions of fault nodes in wireless sensor networks(WSNs)on data aggregation， this paper proposes an algorithm of trust-based secure data aggregation for WSNs. The algorithm is based on multi-layer non-uniform clustering network topology to achieve secure data aggregation， which can effectively balance the network energy consumption. The trust evaluation model is established based on the communication behavior and data correlation among the nodes. The dynamic trust integration mechanism and update mechanism are introduced to realize the trust evaluation intra-cluster and inter-cluster. Based on the trust value， a trusted aggregation node is chosen in the cluster to complete data fusion of trusted nodes. Simulation results show that the algorithm can achieve accurate and effective trust evaluation， identify internal malicious nodes， and obtain the data aggregation results with high accuracy. References | Related Articles | Metrics

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A Distributed File System Based on HDFS LIU Jun， LENG Fang-ling， LI Shi-qi， BAO Yu-bin 2019, 40 (6):  795-800.  DOI: 10.12068/j.issn.1005-3026.2019.06.007 Abstract ( 918 )   HTML   PDF (686KB) ( 1086 )   This paper establishes an intelligent big data storage system IHDFS， based on the existing open source distributed file storage system HDFS. The system proposes and implements big data de-duplication module， big data placement module， big data intelligent migration module， and big data encoding module， which improves the efficiency of user visits and saves the storage space of the cluster. Experimental results show that the data de-duplication module can save the storage space. The data placement module provides a reasonable distribution of file upload storage layer， which twice the uploading speed; the data intelligent migration module improves the hit rate of files on the upper storage layer， which improves the efficiency of obtaining data; the data encoding module saves the storage space of the cluster about one third of the original. References | Related Articles | Metrics

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Improved PTS Algorithm Based on Correlation Analysis in O-OFDM System JI Ce， MA Fu-yong 2019, 40 (6):  801-806.  DOI: 10.12068/j.issn.1005-3026.2019.06.008 Abstract ( 593 )   HTML   PDF (509KB) ( 595 )   In order to solve the problem of peak-to-average power ratio of optical orthogonal frequency division multiplexing system， a partial transmission sequence algorithm based on correlation analysis is proposed. By analyzing the correlation among the alternative signals， the algorithm classifies the strong correlation signal and the weak correlation signal， and searches the strong correlation signal selectively and the weak correlation signal completely， thus reducing the searching times on the whole. In addition， this paper optimizes the phase factor weighting process by analyzing the relationship between alternative phase factor sequences. The simulation results show that the peak-to-average power ratio of the system can be improved effectively under the three segmentation states. Especially in the interleaved segmentation state， the proposed algorithm is compared with the traditional partial transmission sequence algorithm. The proposed algorithm is with no-performance loss of peak-to-average power ratio， and the computational complexity is greatly reduced. References | Related Articles | Metrics

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Channel Assignment Strategy for Low Earth Orbit Satellite Communication LIU Jun， LI Guo-jia， WANG Jing， LI Zi-nan 2019, 40 (6):  807-812.  DOI: 10.12068/j.issn.1005-3026.2019.06.009 Abstract ( 731 )   HTML   PDF (664KB) ( 690 )   For the low earth orbit satellite communication， in view of the characteristics of low altitude， fast speed and frequent switching， single channel allocation strategy cannot improve the experience of more users and the utilization of channel resources under a low traffic scene. The adaptive channel reservation strategy based on differential evolution algorithm for high traffic conditions is proposed， which dynamically adjusts the number of channel reservation to ensure the timely access of high priority users. For low traffic， the non-reserved channel allocation scheme is put forward to meet the ideal bandwidth requirements of high priority users and to make full use of the channel resources of the system. In addition， to further improve the user experience， taking into account the comprehensive priority， the enhanced queuing strategy allows users that are unable to access to join the waiting queue temporarily when all the cell channels are occupied. Experiments show that the scheme can effectively improve the utilization rate of system resources and guarantee the quality of service of high priority and user experience， and make the whole system service quality better. References | Related Articles | Metrics

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An Adaptive Dynamic Load Balancing Model ZHAO Ting-lei， QIAO Jian-zhong， LIN Shu-kuan， WANG Yan-hua 2019, 40 (6):  813-818.  DOI: 10.12068/j.issn.1005-3026.2019.06.010 Abstract ( 575 )   HTML   PDF (1247KB) ( 613 )   To improve the distributed system performance which is affected by load unbalance， this paper proposes and implements an impulsive and switching load balancing model with time delay based on control theory. The model constructs the corresponding sub-system according to the dynamics of node resources. The overloading is migrated by the load migrate rule， of which the migrate proportion is calculated by real-time running states of nodes. Only on this moment， the node broadcasts its message to others. Thus， the communication cost among nodes decreases， and the efficiency of dynamic load balancing increases. This paper provides the corresponding load balancing algorithm and conducts the evaluation on a real platform. Experimental results demonstrate that compared with other load balancing algorithms， the load balancing time of the proposed model is reduced by 29.82% on average. References | Related Articles | Metrics

Mechanical Engineering

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Moving Capability Analysis of a Hexapod Robot over Rugged Terrains CHEN Jie， LIANG Zhong-chao， LIU Chong， ZHAO Jie 2019, 40 (6):  819-824.  DOI: 10.12068/j.issn.1005-3026.2019.06.011 Abstract ( 694 )   HTML   PDF (1269KB) ( 776 )   The grasp of the moving capability of a robot is crucial to the motion planning and control of the robot. The moving capability of a hexapod robot which is used over rugged terrains is thus analyzed. First， the hexapod robot platform as well as the system design is introduced. Then， the kinematic models of the hexapod robot leg and the parallel mechanism consisting of the robot torso and each support leg are built respectively. Their workspaces are also analyzed. Finally， the hexapod robot simulation platform with a rugged terrain is built based on Adams and Matlab， and the motion simulation with the hexapod robot is performed. Results show that， through reasonable motion planning that takes account of both the moving capability and terrain profiles， it is possible to effectively enhance the mobility of a hexapod robot over rugged terrains. References | Related Articles | Metrics

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Research on the Structure Design and Steering and Obstacle-crossing of a Novel Four-Arm Inspection Robot FANG Li-jin， ZHU Shuai， HE Chang-lin， XU Ji-qian 2019, 40 (6):  825-830.  DOI: 10.12068/j.issn.1005-3026.2019.06.012 Abstract ( 745 )   HTML   PDF (1064KB) ( 1035 )   Based on the working task requirements of an inspection robot and the characteristics of obstacles on high voltage transmission lines， a novel four-arm inspection robot was proposed. The robot was composed of three serial poles which were connected by a three-shaft composite rotary joint and a two-shaft composite rotary joint. The robot can meet the requirements of gravity balance by adjusting its joint angle when it steers and crosses obstacles. The gravity balance condition and the postures of steering and obstacle-crossing were analyzed， and the Adams simulation software was used to simulate the whole process of steering and obstacle-crossing. Finally， an experiment of the robot was carried out. The simulations and experiments showed that the inspection robot is able to steer and cross obstacles， and it can keep gravity balance. References | Related Articles | Metrics

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On the Fault Analysis and Reliability Evaluation of CNC Machine Tools QI Yang， GONG Ya-dong， LIANG Chun-you， LI Peng-fei 2019, 40 (6):  831-834.  DOI: 10.12068/j.issn.1005-3026.2019.06.013 Abstract ( 655 )   HTML   PDF (391KB) ( 785 )   Aiming at the phenomenon that conventional CNC machine tools only consider the failure time interval but ignore the nature of faults， a mixed Weibull distribution model combining mechanical failures with electrical failures is proposed to further improve the accuracy of the model. The maximum likelihood method is used to determine the mixed Weibull distribution model parameters， and the Pearson correlation coefficient method is applied to determine the relationship of fault times for the CNC machine tool. The K-S method is used to verify the model and obtain the mixed Weibull distribution model at last， and the mean time between failures(MTBF)of the CNC machine tool is obtained by using the reliability evaluation method. References | Related Articles | Metrics

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Study on the Grinding Surface and Subsurface Quality of Novel Point Grinding Wheels YIN Guo-qiang， GONG Ya-dong， LI Yu-qing， SONG Jun-li 2019, 40 (6):  835-840.  DOI: 10.12068/j.issn.1005-3026.2019.06.014 Abstract ( 604 )   HTML   PDF (1017KB) ( 602 )   Different from the traditional cylindrical grinding， the axis of a grinding wheel is not parallel to the workpiece axis in the point grinding process， but rotates at an inclining angle α. A novel grinding wheel with angle θ is proposed， which is featured by high grinding rate and small surface roughness. Because of α and θ， the contact between the grinding wheel and workpiece has been changed， and the surface/subsurface quality is also changed. The novel wheels with different angles θ are used to grind QT700 workpieces. Then， the metallographic structure， work hardening and residual stress of the workpiece surface/subsurface are tested. The influence of α， θ and grinding parameters on the surface/subsurface quality is analyzed， and the process parameters for optimal surface/subsurface quality are obtained. In conclusion， the novel point grinding wheel can improve the surface/subsurface quality of workpieces. References | Related Articles | Metrics

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Development of a Fiber-Reinforced Composite Material Parameter Tester Based on Laser Non-destructive Scanning LI Hui， WU Teng-fei， XU Zhuo， HAN Qing-kai 2019, 40 (6):  841-846.  DOI: 10.12068/j.issn.1005-3026.2019.06.015 Abstract ( 654 )   HTML   PDF (820KB) ( 574 )   A material parameter tester of fiber-reinforced composite materials based on the laser non-destructive scanning technique is developed. Firstly， by taking the fiber-reinforced composite beam specimen as an example， the theoretical solutions of natural frequencies and vibration responses are deduced. Then， an appropriate step size is chosen to construct the iterative vector of the material parameters， and the theoretical principle for identifying the fiber-reinforced composite material parameters is explained in details. Next， the excitation platform， laser scanning device， signal generator and data acquisition device are utilized to establish the hardware structures， and the functions as well as the control and measurement advantages of the software and corresponding modules based on LabVIEW are also described. Finally， by using this instrument， the material parameters of three TC500 carbon fiber/resin composite beam specimens in different fiber directions are identified， which are also compared with the material results provided by the manufacturer. The results show that their deviations are in the range of 0.63%~10.61%， which is within an acceptable level. Therefore， the reliability of the developed composite material tester and the effectiveness of the related algorithm have been verified. References | Related Articles | Metrics

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Off-Axis Digital Holographic Microscopic Phase Automatic Compensation Method MA Shu-jun， LIU Wei-hua， ZHOU Peng-fei 2019, 40 (6):  847-851.  DOI: 10.12068/j.issn.1005-3026.2019.06.016 Abstract ( 547 )   HTML   PDF (954KB) ( 632 )   In the off-axis digital holographic microscopy， off-axis optical paths tend to cause tilted phase distortion during the digital reference light reconstruction， which seriously affects the quality of the reconstruction. A method of automatic distortion compensation is proposed to study the digital holographic reconstruction process. By processing the frequency domain of the hologram， the corresponding relationship between the angle of the first term and the DC term is found， and the multi-pixel coordinate calculation is used to obtain the corresponding tilted digital reference light. The digital reconstruction is performed using the tilted digital reference light， then the reconstructed phase is binarized， and the optimal compensation phase is found using the maximum connected region to realize the automatic phase compensation. The experiment proves that this method is effective and can realize the automatically eliminating tilt phase distortion. References | Related Articles | Metrics

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Effect of Porous Structure on Mechanical Properties of Vero White Photosensitive Resin YU Tian-biao， ZHAO Yu， BI Xiao-xi， CHEN Ya-dong 2019, 40 (6):  852-856.  DOI: 10.12068/j.issn.1005-3026.2019.06.017 Abstract ( 623 )   HTML   PDF (795KB) ( 682 )   The design of porous structure is one of the main factors that affect performance. It is an important way to reduce the material mass by optimizing porous structure. Static mechanics simulation is used to analyze the change rules of different plate inner structures. Israel Objet Eden250 stereo lithography apparatus is used to solidify different structures of Vero White photosensitive resin， AG-Xplus electronic universal testing machine is used to test the compressive properties of samples， and the simulation results are compared as well. The results show that the compressive strength of porous structure reduces with the increase of porosity， and the value of different structures is in the range of 15~70MPa. The honeycomb structure has a better performance than the hexahedron structure， and the hexahedron structure has a better than the octahedron structure. The results are basically consistent with the theoretical results， which provide a theoretical and experimental basis for the successful application of porous structure in the additive manufacturing. References | Related Articles | Metrics

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Reconstruction Algorithm of Machine Tool Flatness Error Profile Based on Mutative Scale Method LU Ze-chen， ZHAO Chun-yu， LIU Zhi-xue 2019, 40 (6):  857-861.  DOI: 10.12068/j.issn.1005-3026.2019.06.018 Abstract ( 620 )   HTML   PDF (735KB) ( 584 )   In order to solve the problem that the flatness measurement of the installation surface of machine tool guides in China cannot be digitally described， a new method of flatness error detection of the guide rail mounting surface of numerical control machines was proposed based on the mutative scale theory， whereby the total length of the mounting surface can be measured by splicing several short mounting surfaces with overlapping areas. The new instrument was designed and the measurement principles were made. The theoretical model of the algorithm was established by utilizing the geometric relationship between the reference plate， the measuring instrument and the installation surface of the machine tool guideway. And an algorithm for reconstructing the flatness error profile of the installation surface of the machine tool guideway was developed and simulated. The results demonstrated that the algorithm can reconstruct the flatness error profile of machine tool guides’ installation surface accurately. References | Related Articles | Metrics

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Effect of Forward-Swept Angles on Performance of Axial Cooling Fans for Vehicles XIE Yi， XU Meng-tao， LI Kui-ning， ZHENG Yun 2019, 40 (6):  862-868.  DOI: 10.12068/j.issn.1005-3026.2019.06.019 Abstract ( 694 )   HTML   PDF (1545KB) ( 821 )   The parameter models of forward-swept angles of cooling fans for vehicles were established. Their flow fields were simulated by using computational fluid mechanics method， and the effect of forward-swept angles on the flow field， volume flow rate and resistance torque of cooling fans was researched. In terms of pressure distribution， the results showed that at the same ration speed， the average air pressure at the inlet of cascade increases with the forward-swept angle and both the gradient and the pressure difference between blade lift-surface and blade suction surface falls with the forward-swept angle. In terms of velocity distribution， at the same rotation speed of cooling fans， the air velocity at the inlet of cascade decreases and the rise in the air velocity goes down with the forward-swept angle. In terms of the performance of cooling fans， at the same rotation speed， both fan volume flow rate and fan resistance torque reduce with the forward-swept angle. References | Related Articles | Metrics

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Research on Load Capabilities of 45# Steel via In-situ Three-Point Bending Tests LI Cong， ZHAO Hong-wei， SUN Lin-lin， YU Xiu-juan 2019, 40 (6):  869-874.  DOI: 10.12068/j.issn.1005-3026.2019.06.020 Abstract ( 670 )   HTML   PDF (1865KB) ( 783 )   The load capabilities of 45# steel V-notched specimens under the spans of the supporters and the offsets between the punch and the mid-span of the specimens are studied by the self-made in-situ three-point bending device. Firstly， the relationship of load-delection curves and offsets and spans are analyzed theoretically. Secondly， the simulated minimum plastic zone radius of von Mises stress is applied to estimate the initiation direction of the crack. Then the experimental three-point bending loading-deflection curves under various offsets and spans are achieved and analyzed by in-situ TPB tests with 12 groups of V-notched specimens. Finally， according to the differences among the load-deflection curves， combining the in-situ images of specimen micro-structures， the initiation and propagation of the cracks due to bending loads are analyzed in real time. The relationship between macro-mechanical properties and micro-mechanical properties are established by in-situ observation. The difference of the load capabilities of materials under different three-point bending test parameters is analyzed from the perspective of damage mechanism. References | Related Articles | Metrics

Resources & Civil Engineering

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Thermodynamic Analysis of the Reduction Process of Fluorapatite SUN Yong-sheng， LI Yan-feng， WANG Ding-zheng， HAN Yue-xin 2019, 40 (6):  875-880.  DOI: 10.12068/j.issn.1005-3026.2019.06.021 Abstract ( 700 )   HTML   PDF (734KB) ( 889 )   A thermodynamic analysis on the reduction of fluorapatite in different systems was conducted by using the FactSage 6.4 thermochemical software. The effects of some components of high-phosphorus oolitic iron ore on the reduction of fluorapatite were studied. Results show that under non-additive condition， the defluorination of fluorapatite can be initiated at 1174℃ to produce Ca3(PO4)2 and CaF2; fluorapatite can be reduced to CaF2， CaO and P2 by carbon at 1439℃. CaO has no direct effect on the reduction of fluorapatite， while the minimum thermodynamic reduction temperatures of fluorapatite can be decreased by SiO2， Al2O3 and Fe from 1439℃ to 1204， 1247 and 1277℃ respectively， which can facilitate the reduction process of fluorapatite. The thermodynamic results obtained are in good agreement with the available experimental results in the literatures， which indicates that thermodynamic analysis can be used to study the reduction characteristics of phosphate ore. References | Related Articles | Metrics

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The Evaluation Model and Method Based on Cloud Theory LIANG Li， XING Guan-hua， WU Feng-yuan 2019, 40 (6):  881-885.  DOI: 10.12068/j.issn.1005-3026.2019.06.022 Abstract ( 575 )   HTML   PDF (509KB) ( 938 )   An evaluation method based on cloud theory is proposed as follows: firstly， the degree analysis method is used to quantify the qualitative scales so that the cloud model of evaluation criteria can be established; then the index cloud parameters can be calculated according to the normalized measurement range and expert scores to obtain the cloud parameters of the evaluation samples by cloud computing according to the weight of the indexes from layer to layer; finally， a large number of sample points can be generated to calculate the mean value of certainty in the normal cloud generator to be the basis of the final rating. Compared with the evaluation method mentioned above， the certainty degree calculated from the value of expectation of samples can be distorted when there exists a lot of uncertainty. Taking the durability evaluation of stay cables as an example， the effectiveness and operability of the cloud theory method are verified， which proved to be a more scientific method for assessment problem. References | Related Articles | Metrics

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Quantitative Characterization of Microstructure of Gas-bearing Coal in Tunlan Mining Area LI Jiang-tao， LIANG Wen-xu， HE Zhi-hong 2019, 40 (6):  886-890.  DOI: 10.12068/j.issn.1005-3026.2019.06.023 Abstract ( 507 )   HTML   PDF (603KB) ( 590 )   In order to reveal the significance of gas-bearing coal to gas migration， XRD quantitative characterization was carried out on 7 coal samples with different burial depths in Taiyuan Formation of Tunlan Mining Area， and the structural parameters of coal microcrystals were calculated by combining Bragg equation. The results show that with the increase of coalification， the asymmetry of peak(002)gradually decreases， while the corresponding extension length(La)and stacking height(Lc)gradually increase while the interval between layers(d002)decreases. Combined with the mathematical model of coal per unit volume， it is found that there is a significant correlation between permeability coefficient， porosity and ordered phase volume coal. Furthermore， it is proposed that the potential of gas outburst in deep coal seam in Tunlan mining area is higher than that in shallow coal seam， so it is necessary to strengthen the prevention of gas outburst in deep coal seam. References | Related Articles | Metrics

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Analysis of Mechanical Characteristic and Key Technique of Steel Tube Slab Structure JIA Peng-jiao， ZHAO Wen， GUAN Yong-ping， LI Wei-wei 2019, 40 (6):  891-895.  DOI: 10.12068/j.issn.1005-3026.2019.06.024 Abstract ( 635 )   HTML   PDF (1004KB) ( 661 )   Steel tube slab(STS)method is addopted to construct the ultra-shallow-buried subway station of the Aoti Central station， line 9 in Shenyang. The longitudinal and lateral mechanical characteristics of STS structure were investigated， and the interaction mechanism was elaborated; then， the calculation theory of bearing flexural capacity and shear capacity were discussed， and the relative formulas were presented. According to the construction condition， the internal force of STS structure during the construction was calculated. Compared with the left pilot tunnel， the positive mid-span bending moment of the supporting structure increases by 8% when the construction of right pilot tunnel is completed， and the maximum negative bending moment decreases by 17.8%. The maximum deformation of the longitudinal mid-span is 6.46mm. The results can provide some important references for the application and promotion of STS. References | Related Articles | Metrics

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Thermal-Fluid Coupling Simulation on In-situ Unsteady Pyrolysis of Fuyu Oil Shale ZHAO Shuai， SUN You-hong， YANG Qin-chuan， LI Qiang 2019, 40 (6):  896-902.  DOI: 10.12068/j.issn.1005-3026.2019.06.025 Abstract ( 524 )   HTML   PDF (1537KB) ( 709 )   Numerical simulation on heat transfer and permeability of Fuyu oil shale reservoir after hydraulic fracturing was carried out by using thermal-fluid coupling analysis model. It is found that the fluid mainly flows out of the fracture along the oil shale bedding direction. However， as the temperature increases， the porosity increases and a little fluid flows out of the primary pores of the oil shale. The seepage field pressure shows a downward trend in the same section from the fracture perpendicular to the oil shale bedding. The heat conduction of fluid to oil shale formation was mainly in the direction of fracture. As the heating time increases， the oil shale cracks on both sides of the fissure， and with the porosity increase， the diffusion rate of nitrogen to the oil shale reservoir is also improved. After 40 days of heating， the oil shale around the fracture first reaches the cracking temperature. Between 60 and 100 days of heating， the average temperature of oil shale rises from 500K to 650K， and the whole oil shale can be effectively cracked. References | Related Articles | Metrics

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Noise Suppression and High-Frequency Compensation of GRP Data in Curvelet Domain CHENG Hao， WANG De-li， WANG En-de， FU Jian-fei 2019, 40 (6):  903-907.  DOI: 10.12068/j.issn.1005-3026.2019.06.026 Abstract ( 552 )   HTML   PDF (688KB) ( 559 )   This paper proposed a synchronous processing method using random noise suppression and high-frequency compensation for GPR data in curvelet domain. First， the GPR data were transformed into curvelet domain in order to use its multi-angle and multi-scale sparsity. The random noise thus could be suppressed by the adaptive threshold function changed with angle and scale. Second， according to the propagation laws of electromagnetic waves in elastic medium and the curvelet multi-scale feature， the time-varying compensation factor could be calculated so as to inverse weighting the corresponding scale and angle for compensation of the high-frequency absorption. Finally， inverse curvelet transformation was conducted thus the GPR data after random noise suppression and high-frequency compensation could be obtained. This method is totally a data-driven method thus can overcome the influence from artificial factors in traditional method. References | Related Articles | Metrics

Materials & Metallurgy

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Regeneration-Modification of Deactivated V2O5-based Catalyst Used for Low Load Condition Denitration SHANG Da， LI Bao-kuan 2019, 40 (6):  908-912.  DOI: 10.12068/j.issn.1005-3026.2019.06.027 Abstract ( 619 )   HTML   PDF (465KB) ( 583 )   The power plant based deactivated catalyst was characterized by XRD， XRF and BET and the cause of deactivation was determined as As2O3， alkali metal poisoning. However， the crystal structure of the deactivated catalyst did not change and had a high specific surface area. H2C2O4(0.01mol/L) and NH3·H2O(0.015mol/L) was applied to regenerate the catalyst， and the content of SO3， As2O3， K2O and Na2O on the surface of the catalyst could be reduced to 0.09wt.%， 0.05wt.%， 0.02wt.% and 0.01wt.%， respectively. The activity of the catalyst could be recovered after the reloading of 1.5% V2O5. After loading 3wt.% CuO， the catalyst showed good catalytic activity at low temperatures. The NO○x conversion rate of V2O5-CuO/TiO2 at 220， 250， 280 and 310℃ was 62.4%， 82.2%， 90.8% and 95.5%， respectively. References | Related Articles | Metrics