Table of Content

  

20 April 2018
Volume 48 Issue 2

Modified target recognition algorithm based on template matching

DING Xiaoling, ZHAO Qiang, LI Yibin, MA Xin

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  1-7.  doi:10.6040/j.issn.1672-3961.0.2016.377

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Because the local feature extraction algorithm got low recognition rate for poor texture object and it could not recognize the same object from different perspective. A modified target recognition algorithm was proposed. The algorithm used gradient characteristics as features to complete the template matching, which only used the main direction of the gradient and the minor gradient feature was removed by DOT(dominant orientation templates)algorithm. The template feature, which was made binary by fusing affine projection transformation algorithm, could improve the recognition rate of identifying multiple objects at the same time or the same object from different perspective. The experiments demonstrated that the proposed algorithm could get better recognition rate and was robust for the object with poor texture, small deformation, small translation and light transformation.

Airport noise isoline parallel generating algorithm based on grid edge labeling

FENG Xia, HUANG Xixiang

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  8-13.  doi:10.6040/j.issn.1672-3961.0.2017.311

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To solve the problem of large computation and low efficiency in real time dynamic presentation of the airport noise isoline, a kind of isoline parallel generating algorithm based on grid edge labeling was proposed. The parallel generating algorithm adopted the isoline generation strategy from local to global; the grid tasks were assigned by rows; the orientation of the isoline in one grid was setted by grid edge labeling algorithm; all the noise isoline were generated by traversing all the grids only once. The results showed that the algorithm could reach 17 frame/s when the scale of gird was 400×400 and the number of noise levels was 15, which could better satisfy the demand for dynamic noise visualization compared with other algorithms.

Cascaded tracklet-based spatio-temporal model for video pose estimation

SHI Qingxuan, WANG Qian, TIAN Xuedong

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  14-21.  doi:10.6040/j.issn.1672-3961.0.2017.431

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To address the problem of full body human pose estimation in video, a coarse-to-fine cascade of spatio-temporal models was developed in which the tracklet of body part was considered as basic unit. The notion of “tracklet” ranges from trajectory covering the whole video to body part in one frame. In this cascade, coarse models filtered the state space for the next level via their max-marginals. Loops in the graphical models made the inference intractable, the models were decomposed into Markov random fields and hidden Markov models. Through iterative spatial and temporal parsing, optimal solution was achieved in polynomial time. To generate reliable state hypotheses, the pose detections were propagated to whole video sequence through global motion cues. Our model was applied on three publicly available datasets and showed remarkable quantitative and qualitative improvements over the state-of-the-art approaches.

Color image selective segmentation under geometrical constraints

WANG Xueqin, LI Shurong, YU Yu, WANG Jiayan

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  22-29.  doi:10.6040/j.issn.1672-3961.0.2017.067

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In order to solve the specific requirements of selectivity during the course of color image segmentation, an active contour-based color image segmentation method under geometrical constraints was proposed based on the gray image selective segmentation using one level set by Lavdie-Chen. A color image was treated as a whole for the gradient and the edge detection function. The velocity and direction of the curve evolution were determined by the edge detection function, the distance function defined about a set of points near the boundary of the interested region and the inner and outer polygon areas of the given points. Region information could help to overcome the drawbacks of edge functions relying on a single image gradient; the regularization algorithm was introduced to overcome the shortcomings of the poor segmentation effect in the depression;the Euler-Lagrange equation was quickly solved by the additive operator splitting method. Experimental results showed that the proposed color image segmentation method had the characteristics of high validity and high accuracy to selectively segment the wanted region.

Soil pressure distribution behind the basement wall considering the permanent existence of foundation pit retaining piles

LI Lianxiang, LIU Bing, CHENG Xiaoyang

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  30-38.  doi:10.6040/j.issn.1672-3961.0.2016.371

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In order to study the relationship between the soil pressure distribution behind the basement wall and the foundation pit retaining piles, and explore the interaction mechanism between the supporting structure and the underground main structure under the permanent, a Plaxis-3D simulation for a pile-anchor retaining pit was carried out. The results showed that the soil pressure distribution was evidently affected by the piles. The soil pressure increased at first then decreased along with depth, showing an arc shape distribution. The maximum internal force on basement exterior wall decreased and the soil retaining ability strengthened obviously. By fitting the simulation results of several practical engineering, the soil pressure distribution curve was derived and the curve was further simplified to analye the internal force on basement exterior wall. Results proved that the force which was calculated by the simplified curve could well agree with the simulated values. The simplified curve had good applicability in engineering geological condition of Jinan, and provided references for basement exterior wall design when supporting piles existed.

Experiment of cement-based seepage grouting materials for earth-rock dam

LIU Jian, HU Nanqi, XU Baojun, YUE Xiuli, QI Boliang, ZHONG Qi

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  39-45.  doi:10.6040/j.issn.1672-3961.0.2017.066

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In order to solve the problem of poor fluidity and low stone rate of grouting materials commonly used in hydraulic engineering, the experiments were conducted to investigate the improvements on the reinforcement effect of the existing grouting materials as cement, through backfilling fly ash and bentonite in cement as the water reducing agent and expansive agent respectively. Laboratory tests concentrated on investigating the two concerned physical properties of the examined grouting materials—the slurry fluidity and concretion, under different mixture proportions of the backfilled materials. Based on the experimentally obtained results, appropriate material mixture proportions were given based on the optimum improvement on the reinforcement effects. The result showed that bentonite could increase the stone rate of grouting, improve the slurry stability and reduce the slurry fluidity. The addition of appropriate amount of fly ash could improve the slurry fluidity and increase the grouting efficiency. As the proportions of the fly ash and bentonite increased, the concretion strength reduced, so it was suggested to control the mixture proportions of the backfilled materials in order to achieve an optimum strengthening effect. The results provided references for the applications of grouting reinforcement in hydraulic engineering.

Migration behavior of reclaimed mineral aggregate in process of central plant hot recycling

GUO Dedong, ZHANG Shengtao, LI Jin, ZHANG Long, ZHANG Xibin

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  46-52.  doi:10.6040/j.issn.1672-3961.0.2016.488

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To improve the qulity of central plant hot recycling asphalt mixture, a test was designed, including key procedures such as fabricating reclaimded asphalt pavement(RAP), separating new aggregate from mixture and testing migration quantity. By in-laboratory tests, the influences of mixing amount of RAP, mixing time and asphalt content on migration quantity of reclaimed aggregates were evaluated. The results indicated that the reclaimed fine particle mineral aggregates could not disengage from the coarse ones totally during the mixing process of hot recycling asphalt mixture, and the migration quantity of that was about 55% to 75%; the mixing amount of RAP would not change the migration quantity, but longer mixing time and more asphalt content could improve the migration quantity. Migration of reclaimed mineral aggregates would be accelerated by lengthening mixing time properly, adding new asphalt or recycling agent and increasing asphalt content, resulting uniformity of central plant hot asphalt pavement.

Deformation characteristic and instability analysis for shallow soft rock section during tunnel-entering construction

SONG Guijie

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  53-60.  doi:10.6040/j.issn.1672-3961.0.2017.058

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For the collapse accident and stability problem of shallow soft rock section during tunnel construction, tunnel geological conditions were effectively identified, and a 3D model were set up for analysis based on the result of geological radar and the monitoring data of surrounding rock. The results showed that a significant plastic deformation zone was formed on the arch and vault during the tunnel excavation process. With the tunnel face gradually close to the broken zone of the surrounding rock, the range of plastic zone was gradually enlarged and transferred to the top right of the vault and its surrounding rock. The stress level was relatively low. The vertical displacement of the broken area increased significantly, and the integrity of the surrounding rock was greatly reduced. The main reason for the large deformation of the tunnel was the poor geological structure and the mechanical properties of the surrounding rock due to rainfall and surface water infiltration accelerated the tunnel disaster. For the construction of the tunnel soft rock section in the five class surrounding rock, analysis of the monitoring should be strengthened and early warning should be made in time, the advance geological forecast should be developed in the key parts. The results of the study could give guide to the prevention and control of the landslide of the tunnel disaster, which was of great significance for tunnel informatization construction.

The mechanical properties of the silty clay and the advanced support method in Harbin Metro

LI Wei, WANG Zhechao, LI Shucai, DING Wantao, WANG Qi, ZONG Zhi, LIU Keqi

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  61-71.  doi:10.6040/j.issn.1672-3961.0.2017.563

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Based on the Harbin Metro project, the mechanical properties of the silty clay and the selection of the advanced support method were studied with different water content. Through the laboratory tests, including water content test and triaxial test, the type of soil samples from Harbin Metro tunnel was identified as the silty clay and the mechanical properties of soil samples with different water content were determined, and the silty clay of Harbin Metro tunnel was sub-classified according to liquid index. Field monitoring was performed to calibrate the water content-dependent deformation and strength parameters used in the numerical simulations, and the correctness of numerical simulation was confirmed. Numerical simulation was performed with different soil parameters and different support method, and the selections of the tunnel advanced support method with different parameters were obtained by comparing the displacement, stress, stress path and the area of the plastic zone under different conditions. The obtained results could give some help for the selection of the advanced support method of Harbin metro tunnel.

A fault-tolerant control architecture for active magnetic bearing based on dual core processor

CHENG Xin, LIU Han, WANG Bo, LIANG Dian, CHEN Qiang

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  72-80.  doi:10.6040/j.issn.1672-3961.0.2017.610

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To satisfy the fault diagnosis of multi degree of freedom magnetic bearing system and the real-time control requirements, an ARM+DSP based heterogeneous dual core processor architecture was proposed. In hardware configuration, DSP was used as the fault monitoring to execute multiple loops, ARM was used as the main controller to implement the rotor position control algorithm, and the fault-tolerant controller was implemented according to the fault reconfiguration of the controller. In software architecture, a method of information interaction, task allocation and execution based on dual core processor was proposed, and bidirectional interrupt was designed to coordinate the execution sequence between control and monitoring code. In the experiment, the system fault diagnosis and real time fault tolerant control needed only 1.8 ms. Experiment results showed the effectiveness of the proposed architecture.

The relationship between the number of magnetic poles and the bearing capacity of radial magnetic bearing

CHEN Rui, LI Hongwei, TIAN Jing

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  81-85.  doi:10.6040/j.issn.1672-3961.0.2017.607

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The design principles of air gap, magnetic pole, rotor, stator, magnetic pole area and coil were given on the basis of practical engineering experiences. The structures of radial magnetic bearing with different rotor diameter and different magnetic pole number were designed. The finite element analysis software was used to simulate the electromagnetic field of radial magnetic bearing. The electromagnetic force and the magnetic field distribution were obtained. According to the simulation results, the influence of the number of poles on the bearing capacity of bearings under different rotor diameters was studied. The simulation results showed that the capacity of the radial magnetic bearing decreased significantly with the increase of the number of poles when the rotor diameter did not exceed 150 mm. While, the number of poles did not have a significant effect on the capacity of radial magnetic bearings when the rotor diameter reached 150 mm.

Design of H_∞ controller for magnetic thrust bearing system based on V-Gap metric

CUI Hengbin, ZHOU Jin, DONG Jiyong, JIN Chaowu

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  86-93.  doi:10.6040/j.issn.1672-3961.0.2017.591

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The realization of surge control strategy for active magnetic bearing suspended centrifugal compressor with changing tip clearance requires that magnetic thrust bearing system could control the rotor accurately tracking the axial position and deal with the problem of variable axial load. Therefore, to ensure that magnetic thrust bearing system controller satisfy certain position tracking and anti-jamming performances, a precise model for magnetic thrust bearing system was built and combined with the V-Gap metric and the generalized stability margin to design H_∞ controller. First, the V-Gap metric and the generalized stability margin were introduced. Then, the precise model of magnetic thrust bearing system was built and the system parameter uncertainties were analyzed based on the V-Gap metric. Finally, based on the mixed weighted sensitivity H_∞control method, the controller design method based on the generalized stability margin was proposed, and its rationality was verified by experiments. The results showed that the designed H_∞ controller had better robustness and position tracking performance.

Influence of interference fit on the dynamic characteristics of magnetic levitation rotors

LI Peng, WU Huachun, CUI Ruifang, XIONG Zhenyu

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  94-99.  doi:10.6040/j.issn.1672-3961.0.2017.615

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According to the too simple model and the large error problem of modal analysis for traditional magnetic levitation rotors, the contact effect between the rotors was considered. The contact finite element method was used to establish the finite element model of the interference fit of the magnetic levitation rotors. With the combination of theory and static analysis, normal stiffness factor was optimized. By modifying the friction coefficient, the relationship between the interference coefficient and the friction coefficient was obtained, which could provide reference for the similar rotors' accurately analysis of modal. A comparative analysis was made on whether the contact effect was considered for the magnetic levitation rotor. The results showed that it could make the model and the solution more accurate to consider the contact effect.

Joint dispatch control of electrical water heater and inverter air conditioner load group

LIANG Zhiyuan, GONG Qingwu, CHEN Yuanfeng

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  100-106.  doi:10.6040/j.issn.1672-3961.0.2017.237

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For the demand response requirements of the energy internet, a joint dispatch control strategy based on the electric water heater and the inverter air conditioner load group were proposed in order to make the household load response to grid power fluctuation. The advantages of electric water heater and inverter air conditioner as power dispatch backup were explained and the response aggregation model was established. Combining the load characteristics, a joint dispatch control strategy which adjusted the electric water heater firstly and the inverter air conditioner secondly was proposed based on the consideration of the diversity of inverter air conditioner load group. The scheduling dead zone was set based on load dispatch curve to simulate the proposed dispatch control strategy, the effectiveness of the proposed control strategy in power dispatch was verified, which showed that increasing the number of loads could significantly improve the load response of power scheduling ability.

Structural optimization and finite element analysis of a type of axial AMBs

TIAN Jing, LI Hongwei, CHEN Rui, YU Wentao

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  107-113.  doi:10.6040/j.issn.1672-3961.0.2017.609

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One typical structure of axial active magnetic bearings(AMBs)was designed with the given diameters of the shaft and rotor thrust. The influence of the slot structure dimensions on the magnetic field distribution and the bearing force of axial AMB was simulated by using an electromagnetic finite element software when the radial airgap between the stator inner hole and the shaft was unchanged. And the error analysis was given by constructing a magnetic circuit model of the axial AMB. Given the chosen optimized slot dimensions, the influences of the radial airgap of the stator on the magnetic field distribution and the bearing force were analyzed with different rotor shaft diameters. The results showed that the bearing force increased first and then decreased with the increase of the ratio of the axial length to the radial length of the slot. The radial magnetic flux leakage was not the smallest when the ratio was between 5 and 10 but the bearing force was large and stable, and the biggest force was about 88.7% of the theory. With the increase of the ratio of the radial airgap to the axial suspended airgap(airgap ratio), the bearing force increased, but the increment was getting smaller. When the airgap ratio was 13.3, the simulated bearing force was 97.0% of the theory. When the airgap ratio was more than 13.3, the increment of the bearing force was very limited, so the impact was not significant.

Estimation of speed and acceleration of the Maglev platform by state observer

DAI Shiyu, LIU Shuqin

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  114-120.  doi:10.6040/j.issn.1672-3961.0.2017.608

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In order to solve the problem of single pendulum oscillation during the Maglev platform hanging iron, structuring state observer which could estimate the velocity and the acceleration in vertical direction of maglev system was advanced to obtain damping coefficient when the system oscillating. The state observer took signs of coil voltage and sensor feedback information of the suspension gap sign as input and velocity and acceleration in vertical direction of the Maglev platform as state variable. On the premise of maintaining the robustness of the original system, pole of the system was placed after adding the state observer. The results showed that robustness of the system stayed well after adding the state observer. And the state observer could accurately estimate the velocity and the acceleration in vertical direction of the Maglev platform and effectively obtain the real time information of the damping coefficient.

A compound algorithm for SOC estimation of lithium batteries for magnetic suspension artificial heart pump based on UKF and AH

DONG Man, LIU Shuqin

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  121-127.  doi:10.6040/j.issn.1672-3961.0.2017.606

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Based on the nonlinear system, an improved state model was proposed in different cycles and different temperatures; based on unscented Kalman filter and ampere-hour(AH)integral method, a compound algorithm and its concrete implementation steps were proposed for SOC estimation; the convergence speed, estimation accuracy and complexity of the new algorithm were analyzed. The experimental results showed that the complexity of this algorithm was low and the accurate estimation of SOC could be realized quickly, the estimation error was 4.036 2%, and was suitable for real-time on-line computation.

Preparation of an inorganic composite flocculant and its effect on dye wastewater treatment

SUN Shuqing, SUN Fengkai, LIANG Shuang, XU Xiaoli

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  128-133.  doi:10.6040/j.issn.1672-3961.0.2018.002

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With FeCl₃·6H₂O, ZnSO₄·7H₂O, MgCl₂·6H₂O and Na₂SiO₃·9H₂O as main materials, the flocculant poly-silicate ferric zinc magnesium was prepared. The optimal molar ratio of iron, zinc, magnesium and silicon and the impact of initial pH and flocculant dosage on the decolorization rate and sludge volume were investigated through the decolorization experiment of Congo red wastewater. The results showed that the optimal molar ratio of Fe, Zn, Mg and Si was 1∶4∶1∶2. The decolorization rate was higher than 90% during the range of pH 9.0~13.0. Especially at pH=10.0 and 11.0, the decolorization rate reached 99%. Under a certain pH condition, the decolorization performance of the flocculant on the Congo red solution increased and then decreased with the addition of dosage. Sludge volume increased with the increase of pH and flocculant dosage. Especially when pH changed from 11.0 to 12.0, the sludge volume increased nearly 3 times. Compared with the traditional magnesium salt flocculant, poly-silicate ferric zinc magnesium had the advantages of wider pH application range and smaller sludge volume when treating dye wastewater.

pH effect on the structure of Aβ42 fibrils

ZHAO Wei, AI Hongqi

JOURNAL OF SHANDONG UNIVERSITY (ENGINEERING SCIENCE). 2018, 48(2):  134-138.  doi:10.6040/j.issn.1672-3961.0.2018.018

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To find details at atomic level for the association between structure of Aβ42 fibrils and pH, molecular dynamic simulations were preformed to study the changes in structure and property of Aβ42 fibrils at pH 4.0~7.5, by analyzing secondary structures and contents of β-sheet per chain as well as twist angles. The results showed that pH caused little change in secondary structure of fibrils. However, difference existed in content of β-sheet per chain under different pHs. The changes of twist angles and growth of fibril were initiated by the odd tip, responding to the divergence in growth mechanism of fibril.