Journal of Shandong University(Engineering Science)

Twice clustering method based on variable granularity

ZHU Hong, DING Shifei

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 1-6. doi:10.6040/j.issn.1672-3961.3.2014.127

Abstract ( 1621 )

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In order to make up the deficiency of single clustering algorithm, a new twice clustering method based on the variable granularity and clustering network (VGTC) was presented, which combined granularity computing with clustering algorithms together. The aim of the first clustering was to find local data structure through searching an appropriate clustering layer. On this basis, the secondary clustering could complete clustering operation for domain. The creativity of VGTC was that the granularity of clustering could be adjusted by changing clustering algorithm parameters, and the advantages of two clustering algorithms could be combined together through granularity computing. The twice clustering adaptive method of variable granulation based on k-means and hierarchical clustering algorithms(KHVGTC was an example of VGTC) verified the accuracy and efficiency of VGTC algorithm by theory analysis and experimental results.

An outlier detection algorithm based on density difference

XIN Liling, HE Wei, YU Jian, JIA Caiyan

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 7-14. doi:10.6040/j.issn.1672-3961.1.2014.182

Abstract ( 1717 )

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An improved algorithm IMMOD was proposed based on the algorithm MMOD, which considered the difference among different attributes and improved the accuracy of detection. The algorithm introduced entropy to confirm the significance of attribute. The weight of attribute determined by the entropy was used to calculate the weighted distance between objects. In addition, determining and reducing the secondary attributes could guarantee the computational complexity and improve the precision on the high dimensional datasets. The theoretical analysis and the empirical study both showed that the IMMOD could be applied on high dimensional datasets well with a few of parameters and high accuracy, which was better than other algorithms.

An image quality assessment method based on Shearlet transform

REN Yuling, LU Wen, XU Hongqiang, HE Lihuo

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 15-21. doi:10.6040/j.issn.1672-3961.3.2014.172

Abstract ( 1515 )

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An objective image quality assessment metric was proposed by combing the ability of shearlet transform to capture the visual perception feature and the properties of human visual system to describe the degradation of image quality. First, the shearlet transformation was applied to reference and distorted images to obtain the subband coefficients of different scales, and then the contrast sensitivity masking was employed to obtain the subband coefficients of different scales of same perceptual importance. Second, the proportion of perceived coefficients of reference and distorted images was calculated according to the perception threshold, which was obtained from the subband coefficients of reference image. Finally, the objective image quality assessment was acquired by comparing the differences of the proportion of perceived coefficients between reference and distorted images. Tests were done on LIVE database and image sets of distortion at different levels to verify the rationality and validity of the proposed method. Experimental results illustrated that the proposed method had a good consistency with the subjective assessment of human beings, thus could be used to describe the visual perception of the image effectively.

Improved indoor 3-D fuzzy position fingerprint localization algorithm

ZENG Bi, MAO Qin

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 22-27. doi:10.6040/j.issn.1672-3961.3.2014.109

Abstract ( 1295 )

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An improved indoor three-dimensional fuzzy position fingerprint localization method named ITF was proposed to improve the positioning accuracy. Gaussian model was used for filtering the received signal strength of sample nodes and unknown nodes to establish the fingerprint database for sample nodes. Then the problem of solving high order coordinates was transformed into the problem of space membership degree. The fuzzy neartude weights of unknown nodes and sample nodes were calculated, which could determine the coordinates of unknown points. The experimentalresult proved that ITF had higher performance in reducing the error than other traditional algorithms.

Bound gait controlling method of quadruped robot

MENG Jian, LI Yibin, LI Bin

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 28-34. doi:10.6040/j.issn.1672-3961.0.2014.328

Abstract ( 2413 )

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Aiming at the problem of running control of quadruped robot, a running control method based on bound gait was proposed. The bound gait of the quadruped robot was implemented by fast and small range swing motion of the legs. A finite state machine was used to separate one complete cycle of motion into six stages, three stages for fore legs and three for hind legs respectively. In contact and buffering stage, vertical spring-damper model was used; in thrust stage, virtual model was used to adjust the thrust direction of the legs; and in swing stage, Bezier curve was used to plan the trajectory of the toes. By constructing a virtual model with the same size and mass with the hydraulic driven quadruped robot SCalf-II in the dynamics simulation software, the control method was verified and tested, simulation results showed that the robot came into a cyclic bounding motion with strong periodicity after five periods, the speed vibration in forward direction was small, the joint range of motion, speed and torque were all within the range of the design objective of SCalf-II, which verified the correctness and effectiveness of the proposed method.

Signal filtering based on Improved Empirical Mode Decomposition

MU Feng, CHANG Faliang, JIANG Qinyu

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 35-42. doi:10.6040/j.issn.1672-3961.0.2014.376

Abstract ( 1892 )

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To solve the problem that the filtering effect of classical Empirical Mode Decomposition (EMD) algorithm wasn't good in a low SNR environment, an improved EMD filtering algorithm was proposed. Signal spectrum was analyzed with FFT, if there was high-frequency noise in the signal, the first Intrinsic Mode Function (IMF) which was obtained by EMD algorithm was removed. And if there was white-noise or glitch in the signal, a variable factor was added to the classical EMD algorithm then filtered the signal using EMD, and the first IMF was removed at the last iteration of the algorithm. The simulation experimental results showed that the Mean Square Error (MSE) of the improved EMD algorithm was small and the filtering effect was good in the low SNR environment.

Research on coordination of agricultural product supply chain under product circulative characteristics

QIN Fenghua, HU Hongchun, LIU Zhaoqi

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 43-47. doi:10.6040/j.issn.1672-3961.0.2015.029

Abstract ( 1296 )

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Stackberg game model of two level agricultural product supply chain was founded in which the supplier was the leader, the retailer was the follower. Based on sales prices, sales volume and freshness, the optimal decision-making of agricultural product supply chain was analyzed on the assumption of two situations-noncooperation and cooperation. The results showed that the noncooperation had higher prices, lower freshness, less sales volume compared with cooperation. The total optimal profit of supplier and retailer in noncooperation situation was lower than that in cooperation situation. The good performance of the supply chain coordination was verified by the numerical simulation.

One-dimensional modeling and inversion of nuclear magnetic resonance over electrically conductive medium

QI Zhipeng, LI Xiu, ZHAO Wei, ZHI Qingquan, LIU Lei

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 48-57. doi:10.6040/j.issn.1672-3961.0.2014.096

Abstract ( 1275 )

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A 1D (one-dimensional) nuclear magnetic resonance (NMR) modeling and inversion method was proposed, which considered the influence of conductive layered media. The NMR exciting magnetic field was calculated with the frequency domain magnetic field response of layered conductive media. The kernel function was modified in the calculation process and the oscillation was thereby reduced, which made it easier in integration. The 1D NMR modeling considering the influence of conductivity was implemented based on the above technique. For the inversion interpretation, the inversion of water content parameter of water-bearing layers was implemented with hyper plane fitting technique after the geoelectric section was derived from TEM (transient electromagnetic method). The inversion results were basically the same as those derived from commercial software. And the inversion results of the proposed method give more information on stratification.

Vibration analysis of excavator seat based on EEMD and CWT

LU Dan, ZHOU Yiqi

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 58-64. doi:10.6040/j.issn.1672-3961.0.2014.335

Abstract ( 1548 )

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The measured seat vibration responses of an excavator were firstly processed by ensemble empirical mode decomposition (EEMD). In order to eliminate meaningless and spurious components from the obtained intrinsic mode functions (IMF), a new method combining energy contribution ratio and correlation analysis was proposed. Then the selected “interesting” IMFs with actual physical interpretations were processed by continuous wavelet transform (CWT). Based on time-frequency characteristics of IMFs, the vibration signals corresponding to different excitation sources could be located and identified. The experimental results showed that combustion forces and second-order rotation forces of diesel engine contributed mainly to seat vibration, meanwhile, the tangential and radial forces of diesel engine caused by circulated gas pressure in cylinder also made contributions. The proposed method could be employed effectively in decomposing, selecting and locating the seat vibration source signals, which was greatly helpful to further study of riding comfort.

Connection algorithm of bone tissue based on canny edge detection

ZUO Junyan, ZHANG Jianguo, ZHONG Tao

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 65-72. doi:10.6040/j.issn.1672-3961.0.2014.276

Abstract ( 1489 )

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A new edge joint algorithm was investigated based on the image information and characteristic of the pixel, and the connection sequence was formed by edge detection, simplified handling, classification of endpoint information and simulated annealing. The ideal connection of edge contour was accurately generated by combining the feature information of nodes, detecting and computing the end position, selecting an appropriate variance of canny and using a mature labeling algorithm. The simulation of connection process was carried out satisfactorily by means of a package of commercial software MATLAB. The factors affecting the jointing including the theoretical model of joint algorithm and type of endpoint were analyzed. The results showed that the edge could be efficiently connected by joint algorithm which based on simulated annealing and type of endpoints, and the algorithm has good connecting effect in selecting appropriate canny parameters and simplified production process.

The property of die-casting dies of wiper repaired by laser welding with filler wire

LIU Lijun, ZHANG Hongxing, ZHANG Weijie, WANG Gang, QI Meng

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 73-79. doi:10.6040/j.issn.1672-3961.0.2014.225

Abstract ( 1370 )

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In order to solve the problem of cracks on die-casting dies, the method of combining laser technology and bionic technology was used to repair them. Repairing layer on die-casting dies was prepared utilizing the method of laser wire filling welding; the optimal process parameters were obtained through the microstructure observation, hardness analysis and energy-dispersive X-ray analysis. These parameters were that the current was 180 A, the defocusing amount was -10 mm, the laser pulse width was 8 ms, the wire filling speed was 0.032 m/min, and thermal fatigue test and life test of die-casting dies were performed using these parameters. The experimental results showed that hardness of die-casting dies surface were improved, tissue grain was refined effectively, and the life of mold was extended, which could provide a new thought for repairing the die-casting dies.

Reinforcement effect and stability analysis of tunnel horizontal jet grouting of different construction methods

LYU Guoren, ZHOU Hao, LI Li, GAO Quanting, JIANG Zhuchang

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 80-85. doi:10.6040/j.issn.1672-3961.0.2015.067

Abstract ( 1578 )

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In order to solve the stability problem of soft and broken surrounding rock in tunnel construction, the FLAC2D was employed to conduct numerical simulation to a section soft and broken surrounding rock tunnel. The effect of horizontal jet grouting pre-reinforcement was studied, the influence of CRD (center cross diagram) method and three steps method on tunnel construction stability was discussed. According to the analysis results, the jet grouting pre-reinforcement was helpful to control the settlement and lining internal force, the CRD method was recommended for the surrounding rock settlement and lining internal force of CRD is lower, and the excavation of left side of middle bench was the key link, and the lining should be done in time. Based on the analysis, a set of optimization methods of construction technology were put forward and applied in Xiamen highway tunnel, which could provide basis for the smooth construction, and could provide significant reference to similar tunnel construction.

Study on buried abutment slope transformation based on numerical simulation and site detections

ZHU Dengyuan, YAO Zhanyong, GE Shouren

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2015, 45(3): 86-94. doi:10.6040/j.issn.1672-3961.0.2014.040

Abstract ( 1376 )

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In order to get more traffic clearance under bridge during the road upgrading transformation, an internal and external reinforcement program was proposed to the underpass grade separation. The internal program was the soil reinforcement by the Soletanche method to active pressure soil and passive pressure soil of the abutment, and the external program was the anchored retaining wall by tie rods. Based on Abaqus6.10, the nonlinear FEM software, a 3D elastic-plastic numeric model was built to simulate the transformation process from buried abutment slope to anchored retaining wall. Two kinds of the construction processes were simulated, one was the slope soil excavation in layer vertically only and the other was in section horizontally and in layer vertically, and the soil reinforcement area was determined. Based on site detections to the top displacement and the bolt tension force of the retaining wall, stability analysis during the soil excavation and the wall construction were done, and the anchor pull test was carried out. The results indicated that the stability factor of the slope soil excavation program in layer vertically was 1.61, while the program in layer vertically and in section horizontally was 1.84, and the latter program was better. The top displacement of the wall increased mainly during the construction process, and the tension forces of the bolt did not change suddenly, and the wall and the soil behind the wall were stable. The soil reinforcement by the Soletanche method could enhance the soil shear strength and the resistance to deformation, and there was no collapse, fall, and slip during the construction process.

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