Volume 40,Issue 1,2017 Table of Contents

1 Effects of engine block elastic deformation on the lubrication characteristics of main bearings

RUAN Dengfang , GAO Zhenchao , XU Jinxia , XIE Yi

2017, 40(1):1-10. DOI: 10.11835/j.issn.1000-582X.2017.01.001

[Abstract](927) [HTML](532) [PDF 6.11 M](10)

Abstract:
To investigate the effect of the engine block elastic deformation on the lubrication characteristics of main bearings, a multi-flexible body dynamic model was developed with considering the elastic deformation of the whole engine block and crankshaft. Coupled with the generalized Reynolds equation and Greenwood/Tripp contact model based on the mass conserving boundary condition, the lubrication performances of main bearings were obtained. The results show that when the block elastic deformation is taken into account, the variation trend of the lubrication characteristics are coincident with that without considering the deformation of the engine block; the average of outflow and the total friction power loss show little difference, at the same time, the minimum oil film thickness, the peak oil film pressure and the peak asperity contact pressure have significant variation at certain times of an operating cycle.

2 The evaluation of sound quality for automotive door closing sounds with different closing force

XU Zhongming , WU Dan , XIA Xiaojun , HE Yansong , ZHANG Zhifei

2017, 40(1):11-19. DOI: 10.11835/j.issn.1000-582X.2017.01.002

[Abstract](1100) [HTML](439) [PDF 1.99 M](10)

Abstract:
The result of correlation analysis in the subjective preference evaluation illustrates that the strength used to close the automotive door influences the judgment of sound quality seriously. So we acquired and studied the samples of the sounds from the driver's ears when a car's front door was closed heavily and lightly. And a new sound quality evaluation parameter named sharpness-energy (SE) was proposed. Firstly, energies of noise samples were calculated numerically based on dual ensemble empirical mode decomposition (EEMD) and Wigner-Ville distribution. Then SE was acquired through the calculation formula of sharpness. Finally, SE was normalized to a centesimal system. SE underlines the influence of high-frequency component in the judgment of sound quality. In order to verify the validity of the extraction process, we carried out a correlation analysis between SE and subjective evaluation results. The results illustrate that the SE method acquires better performance than sharpness when evaluating the sound of closing door.

3 Torsional vibration analysis of the crankshaft with rigidly coupling CVT

ZHANG Qing , LUO Qiushun , ZHANG Li , QIU Sheng , CHEN Zhaohui

2017, 40(1):20-29. DOI: 10.11835/j.issn.1000-582X.2017.01.003

[Abstract](1081) [HTML](651) [PDF 5.60 M](9)

Abstract:
Due to the limitation of non-road vehicles' structure and cost, a structure of four-cylinder diesel engine crankshaft with rigidly coupling CVT was proposed. Characteristics and working principles of the new structure were presented. Calculation models were established separately for rotational vibration analysis of the newly proposed structure and the crankshaft with clutch. By carrying out the crankshaft front-end experiment, the presented model and the calculation method were validated. After solving both models for torsional vibration characteristics and parameters, results were compared. The comparison indicates that crankshaft with rigidly coupling CVT make the vibration fluctuation and the crankshaft dissipation power increase while the corresponding speed of resonance peak value decreases. The impacts on crank shear stress turn out to be small, while the shear stress tends to decrease at low speed condition and increase at high speed condition. Also, the torsional vibration amplitudes and shear stress at the end of CVT are larger. Through the comprehensive comparison, it can be concluded that the crankshaft with rigidly coupling CVT can be adopted on non-road low-speed four-cylinder diesel engine.

4 Vibration response analysis of helical gear transmission considering the tip relief

YANG Yuliang , WEI Jing , LAI Yubin , ZHANG Aiqiang

2017, 40(1):30-40. DOI: 10.11835/j.issn.1000-582X.2017.01.004

[Abstract](1022) [HTML](777) [PDF 3.74 M](8)

Abstract:
Proper modification of the involute gear could effectively improve its meshing performance, lower the noise and extend its service life. A finite element model of helical gear pair in mesh with different amounts of tip relief was built by ANSYS parameter design language (APDL). Static transmission error and time-varying meshing stiffness with the different amounts of tip relief were calculated by loaded tooth contact analysis. Then, a 12-degree of freedom dynamic model of a parallel shaft helical gear meshing was established with considering the impact of tip relief. And the time-varying meshing stiffness was introduced into the dynamic model to research the influence of tip relief on the vibration response of helical gearing. The results show that the amplitude of radial vibration and meshing force of helical gear system decrease obviously with the increase of tip relief within a certain range, but it has an increase tendency when the tip relief reaches 21 μm. The results are significant to determine the optimal gear profile modification and analyze the vibration characteristics of repaired helical gears.

5 Optimization of setting location and remaining period of blocked-out coal reserves in flat and multi-coal seams surface mine

LIU Chuang , BAI Runcai , LIU Guangwei , CAO Bo

2017, 40(1):41-47. DOI: 10.11835/j.issn.1000-582X.2017.01.005

[Abstract](906) [HTML](584) [PDF 1.41 M](3)

Abstract:
To ascertain economic setting location and remaining period of blocked-out coal reserves in surface mine, with the basic principle of the surface mining and statistical method, we analyzed the characteristics of developing change and its influence on setting location and remaining period of blocked-out coal reserves. Based on the principle of optimal economy benefit, the relationship between setting location of blocked-out coal reserves and internal dumping transportation distance in multi-coal seam surface mine was studied, and an optimization model of setting location of blocked-out coal reserves was built. We also studied the relationship between remaining period of blocked-out coal reserves and stripping cost, transportation cost, time value of money, and built an optimization model of remaining period of blocked-out coal reserves. Taking a surface mine in east of Inner Mongolia as an example, we ascertained the economic remaining period of blocked-out coal reserves in this surface mine should be 6.5 months, and blocked-out coal reserves should be set in 1^# coal seam. The results show that the optimization model can guide production, decrease stripping cost and increase economic benefit of surface mines.

6 Optimal prediction model on sedimentation parameters of pre-magnetized crude tailings slurry

KE Yuxian , WANG Xinmin , ZHANG Qinli

2017, 40(1):48-56. DOI: 10.11835/j.issn.1000-582X.2017.01.006

[Abstract](823) [HTML](645) [PDF 2.14 M](8)

Abstract:
In order to improve the dewatering and concentrating effect of crude tailings slurry (CTR), magnetic treatment technique was introduced into dewatering and concentrating of CTR, and a GA-SVM(genetic algorithm-support velocity machine) model was established to optimize sedimentation parameters of CTR. The SVM model for predicting sedimentation parameters of pre-magnetized CTR was established and trained with sample data got from orthogonal experiments, taking magnetic induction, magnetized time, cycling velocity and mass concentration of CTR, unit consumption of flocculant as input factors, and sedimentation velocity as comprehensive output factor. Then a GA-SVM model for optimizing sedimentation parameters of pre-magnetized CTR could be obtained after parameters of SVM model optimized by the genetic algorithm. Furthermore, the GA-SVM model was adopted into an iron mine's pre-magnetized CTR to optimize its sedimentation parameters, and the optimized sedimentation velocity was about 155 cm/h when magnetic induction, magnetized time, cycling velocity of CTR and unit consumption of PAC flocculant was 0.192 T, 1.85 min, 1.92 m/s and 28 g/t, respectively. The study results show that dewatering and concentrating effect of CTR could be improved and PAC could be saved by 40% under suitable condition of magnetic treatment. For optimizing sedimentation parameters of pre-magnetized CTR, the relative prediction error of GA-SVM model was less than 5%, which suggests that the GA-SVM model has higher prediction precision. The study also providing a new method to CTR's dewatering and concentration as well as its parameter optimization.

7 FEM analysis of RC T-beams strengthened with unbounded pre-stressed CFRP belts anchored on multiple points

CHEN Xiaoying , ZHUO Jing , LI Tangning , CHEN Mingzheng , ZHU Langtao

2017, 40(1):57-64. DOI: 10.11835/j.issn.1000-582X.2017.01.007

[Abstract](816) [HTML](317) [PDF 3.38 M](6)

Abstract:
Four simply supported reinforced concrete T-beams strengthed with externally unbonded prestressed CFRP belt were simulated by nonlinear finite element analysis using the general purpose commerical program ABAQUS. Three beams were strengthed on each side symmetrically and one beam was strengthed on bottom based on a four-point tooth waveform anchor.The analytical results show good agreement with test results on flexural capacity, elastic deformation, and ultimate flexural capacity.However the inelastic deformation of the analytical simulation has significant discrpency with that observed in the test.Therefore, to some extent, the finite element analysis can be an effective alternative to the experimental test. Based on the parameters of TL3 beam which shows the best match between the finite element analysis and the test, "two-point anchoring" and "four-point anchoring" models were designed and simulated. By comparing the results of "two-point anchoring" and "four-point anchoring" models, the method for changing the amount of CFRP and the number of anchor points based on the moment of member can not only ensure non-reduction of strengthing effect, but also can save CFRP material.

8 Calculation of sand slope stability with considering seepage and earthquake

LU Yulin , BO Jingshan , CHEN Xiaoran , WANG Li

2017, 40(1):65-75. DOI: 10.11835/j.issn.1000-582X.2017.01.008

[Abstract](978) [HTML](495) [PDF 2.47 M](8)

Abstract:
On the basis of the limit equilibrium theory, we took a sand slope as research object and deduced the expressions of the slope safety factor with quasi-static method and pseudo-dynamic method when steady seepage and earthquake were present. The results of computer programs agree well with those of exiting methods, which verifies the validity of the two analytic methods. Parameter analysis shows that there is a linear relationship between hydraulic gradient and safety factor, and the higher the water level, the easier the slope is to lose stability. When the seepage direction is downward, the slope stability increases with the increase of hydraulic gradient, and when the seepage direction is upward, the change rule is opposite. The slope stability increases significantly with the increase of horizontal seismic acceleration factor, and the effect of vertical seismic acceleration factor on the slope stability is relatively small, which can be ignored in simplified calculation. Generally, the analytic formula of pseudo-static method is simple and practical, and the formula of the pseudo-dynamic method can more comprehensively investigate the characteristics of the slope stability changing with time.

9 Effects of boron on the microstructure of second generation Ni-based single crystal superalloy

ZHAO Yunsong , LUO Yushi , ZHANG Jian , GUO Huiming , FANG Xiang , TANG Dingzhong

2017, 40(1):76-85. DOI: 10.11835/j.issn.1000-582X.2017.01.009

[Abstract](1075) [HTML](386) [PDF 6.52 M](3)

Abstract:
Boron (B) is added into single crystal superalloys as a micro-alloying element to strengthen low angle grain boundaries. However, there are limited systematic investigations about the effect of B on the microstructures of single crystal superalloy. We studied the influences of B on phase transition temperature, (γ+γ') eutectic and borides by analyzing the quantitative characterization of the as-cast and heat-treated microstructures of 3 kinds of second generation Ni-based single crystal superalloys DD11 with various additions of B (mass fraction of 0, 0.01% and 0.02%). The results indicate that increasing B addition can significantly decrease the solidus and liquidus temperature and enhance the volume fraction of (γ+γ') eutectic. The borides of M₃B₂ are not observed in the alloy with 0.01% B addition. However, when the B addition is 0.02%, the script-like borides are precipitated in the interdendritic region and the incipient melting point is decreased, and thus the volume fraction of residual eutectic is significantly improved. The script-like borides are rich in Cr, Mo and W, which decreases the solid solution strengthening effect, and thus creep properties of the alloy may be significantly decreased. This study would be helpful for the understanding of B's role in Ni-base single crystal superalloys and the optimization of B content.

10 Congestion-control-based assembly algorithm in OBS networks

WANG Linlin , WANG Chengliang

2017, 40(1):86-92. DOI: 10.11835/j.issn.1000-582X.2017.01.010

[Abstract](906) [HTML](494) [PDF 2.14 M](2)

Abstract:
The communication performance of optical burst switching(OBS) networks is limited because the interaction between the assembly algorithm of edge nodes and the data scheduling algorithm of core nodes isn't considered in traditional OBS network assembly algorithm. After analyzing the influence of the assembly algorithm of edge nodes on the data scheduling of core nodes, we proposed a novel assembly algorithm of edge nodes, i.e. congestion-control-based assembly algorithm (CCAA) in OBS networks. The algorithm improves the success probability of core-node-data scheduling and enhances the performance of OBS networks by analyzing the influence of the assembling parameter of edge nodes on data scheduling and adjusting the assembling algorithm to affect the success rate of core node scheduling.

11 MR image reconstruction by combining local and global sparse representations

GE Yongxin , LIN Mengran , HONG Mingjian

2017, 40(1):93-102. DOI: 10.11835/j.issn.1000-582X.2017.01.017

[Abstract](1315) [HTML](596) [PDF 6.79 M](6)

Abstract:
The compressed-sensing-based methods use the global or the local sparse dictionaries separately, which respectively results in the loss of image details or overall structures of MR(magnetic resonance) images. In order to solve this problem, a novel imaging algorithm combining both local and global sparse constraints was proposed to capture details and overall structures of MR images. Firstly, a spare dictionary was trained from specific MR images, and then the local sparse representations were obtained via the dictionary. Secondly, traditional analytical dictionaries were used to promote the global sparse structures of MR images. Finally, the reconstruction was solved by using a nonlinear conjugate gradient with the known local and global sparse constraints. This procedure was repeated iteratively to improve the quality of reconstruction. And experimental results demonstrate that compared with the dictionary learning magnetic resonance imaging method (dictionary learning MRI, DLMRI), the proposed algorithm can improve the image reconstruction by 1-6 dB when the reduction factor is up to 10.

12 Sensor subset selection algorithm in FM-based passive radar network system

DAI Chunliang , SHI Chenguang , ZHOU Jianjiang , WANG Fei

2017, 40(1):103-112. DOI: 10.11835/j.issn.1000-582X.2017.01.018

[Abstract](954) [HTML](317) [PDF 2.19 M](6)

Abstract:
A novel sensor subset selection algorithm for target parameter estimation in frequency modulated(FM)-based passive radar network was proposed to realize the dynamic coordination of FM signal receivers. By selecting an optimal subset of FM receivers with predetermined subset size, this algorithm can achieve better performance under limited resources. The algorithm uses the coherent Cramer-Rao lower bound (CRLB) as the cost function, and solves the optimization problem by greedy heuristic algorithm. The simulation results show that the proposed algorithm can not only improve the performance of target parameter estimation under limited system resources, but also greatly reduce the calculation amount, and thus has a strong practicability.

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