Volume 42,Issue 5,2019 Table of Contents

1 Mapping model of packing seals preload on wear and leakage

ZHOU Jie , CAO Qingyuan , WANG Shilong , YI Lili

2019, 42(5):1-9. DOI: 10.11835/j.issn.1000-582X.2019.05.001

[Abstract](752) [HTML](571) [PDF 1.20 M](1612)

Abstract:
Nuclear power has high requirements for related equipmentdue to its radioactivity. Packing seal is a dynamic sealing method widely used in nuclear power machinery between holes and axles. The greater preload force on the packing seal, the better the sealing effect, but the wear rate will increase, shortening the service life. Therefore, the study of the influence of preload on wear and leakage has been analyzed in this paper. The mapping model for determining the relationship between preload and the leakage rate, as well as the service life were established. The key parameters of the model were identified based on experimental data. The final model of wear and leakage was obtained. Finally,the accuracy of the revised model was verified by experiments.

2 An equidistant offset algorithm of rotation curve to solve conjugate gear profile

LI Guolong , REN Weixian , XIE Tianming , HE Kun

2019, 42(5):10-18. DOI: 10.11835/j.issn.1000-582X.2019.05.002

[Abstract](1007) [HTML](1039) [PDF 1.19 M](1108)

Abstract:
In order to solve the problem of singular point in the traditional algorithm for solving conjugate gear profile, an equidistant offset algorithm of rotation curve was proposed. The equidistant offset characteristics of conjugate curves were analyzed and the equations of equidistant offset line of rotation curve were derived. By way of arc approximation, equidistant offset line family of rotation curve was used to solve conjugate curves of any gear profile, and the involute profile curve with a cuspidal point of addendum was taken as an example. The principle error of this algorithm was analyzed, and a method to solve precise conjugate points was proposed. Compared with the traditional method of solving conjugate gear profile, the equidistant offset algorithm of rotation curve has no singular point problem, and there is no need to solve the meshing equation. It has obvious advantages in solving conjugate gear profile with singular points and small change rate of curvature radius.

3 Application analysis of a novel tilted coordination body sense algorithm for flight simulator

WANG Hui , ZHANG Baofeng

2019, 42(5):19-26. DOI: 10.11835/j.issn.1000-582X.2019.05.003

[Abstract](724) [HTML](608) [PDF 1008.15 K](1051)

Abstract:
After a sudden and overloaded motion,there is a large sensory error between translational low frequency output continuous acceleration and reference acceleration by classic filter algorithm. In order to improve the dynamic fidelity of the simulator,a novel tilt coordination somatosensory algorithm is proposed for the classical washing algorithm structure.Based on the fuzzy logic compensation idea,the signal error and the rate of change of human sensory model were used as input compensation of the fuzzy controller in the tilted coordination channel. The low-pass filter was removed and the input signal of the low pass filter was replaced with the difference between the input reference signal and the translational high frequency signal and the fuzzy compensation synthetic signal in combination with secondary filtering of translational highpass angular acceleration to compensate angle displacement and acceleration compensation,optimizing the washing effect in a limited space. A simulation of the aircraft acceleration signal is done and the results show that the proposed algorithm brings a great improvement in phase delay and false hints,while extending the range of motion and increasing the simulation fidelity.

4 Research on integrated retaining wall constructed with soilbag

LU Liang , ZHI Xianping , WANG Zongjian , HUANG Hui , WU Jinming

2019, 42(5):27-36. DOI: 10.11835/j.issn.1000-582X.2019.05.004

[Abstract](730) [HTML](907) [PDF 2.49 M](858)

Abstract:
The lack of friction between soilbags was the main reason for poor integrity of soilbag flexible retaining wall. At present,there are few researches about how to enhance integrity of soilbag retaining wall. In order to improve the wall structure of the traditional soilbag retaining wall,integrated soilbag flexible retaining wall structure which has the advantages of good integrity,and strong ability of deformation coordination was proposed. Combined with the laboratory model test,the wall displacement and stress distribution law of the tension device were studied under the vertical and horizontal loads of integrated soilbag flexible retaining wall structure with sand as filler. A comparison is made between the flexible retaining wall and the traditional soilbag and the reinforced retaining wall in terms of the horizontal bearing capacity,deformation mechanism and stability. The flexible retaining wall produces an integrated effect and formes a continuous wall,which effectively controls the deformation of the wall surface and improves the deformation ability of the wall,so the stability and horizontal bearing capacity are higher than that of the conventional soilbag retaining wall.

5 Research on bottom column end moment amplification factor of RC frame based on incremental dynamic analysis and fragility analysis

ZHANG Wangxi , PANG Bo , XU Shuai

2019, 42(5):37-45. DOI: 10.11835/j.issn.1000-582X.2019.05.005

[Abstract](741) [HTML](454) [PDF 1015.58 K](835)

Abstract:
In order to study the reasonable value of the bottom column end moment amplification factor of the RC frame structure and the rationality of the value of this factor according to the current codes, six RC frame structure models were designed with various column end moment amplification factors and fortification intensity.The models were analyzed based on incremental dynamic analysis by inputting 10 seismic waves to obtain the IDA curves of the structures. On the basis of the IDA, different intensity levels were defined, and the fragility curves and the failure probability of collapse of each structure were obtained. The results shows that the RC frame structure at 7 or 8 degree fortification in accordance with the current codes can satisfy the fortification reqirements for "No Collapsing in the Strong Earthquake"; when the values of column end moment amplification factor and the beam column joint are raised to 1.5 and 1.7 respectively, the probability of collapse under the large earthquakes will be acceptable.

6 Effect of loading rate on Kaiser effect of sandstone under tensile stress

FU Xiang , HUANG Ping , BAN Yuxin , XIE Qiang , ZENG Jing , TU Yiliang

2019, 42(5):46-55. DOI: 10.11835/j.issn.1000-582X.2019.05.006

[Abstract](702) [HTML](842) [PDF 3.55 M](714)

Abstract:
The paper aims at recognizing the Kaiser effect characteristics of rock tensile failure process with the change of loading rate and acquiring the mechanism and criteria. Firstly, the relationship between Kaiser point stress, loading rate, acoustic emission (AE) parameters were studied. Then, the RFPA2D software was used to simulate the test process from the perspective of micro-crack development. The mechanism of the difference between the Kaiser effect induced by the change of loading rate during the test was analysed. Finally, the spectral characteristics of the Kaiser point under tensile stress was obtained by wavelet analysis and the judging criteria for macroscopic phenomena was quantified. The results show that the KE characteristic parameters of sandstone positively correlated with loading rate. There are great differences in Kaiser point of each parameter, especially in that of the cumulative energy. The faster the loading speed, the weaker the regularity of the rock crack propagation path. Changes of the trend of the crack competition results in the uniformity of the cracking energy distribution, which affect the obviousness and identification accuracy of the Kaiser effect. The frequency of the Kaiser point is mainly concentrated within the range of 0 kHz to 312.50 kHz with normal distribution, accounting for 41.73%, and the maximum value distributes around 300 kHz. The frequency range of Kaiser point shows a constant tightening trend with the change of loading rate, which can be used as the basis for reasonable selection of experimental loading rate for different rocks. The results can provide reference for the stability monitoring, early warning and forecasting work of rock mass roof or compartment rock under bending stress.

7 Modeling of influenced area after slope failure based on smoothed particle hydrodynamics (SPH)

HU Man , WU Fei , WANG Shiji , ZHANG Fuyu

2019, 42(5):56-65. DOI: 10.11835/j.issn.1000-582X.2019.05.007

[Abstract](659) [HTML](400) [PDF 3.71 M](1027)

Abstract:
The modeling of the influence scope after slope failure is one of the important approaches to quantify the risk of landslide hazard. In this paper, based on the Smoothed Particle Hydrodynamics (SPH) method, the classical elastoplastic constitutive model was employed to study the application of a more accurate and convenient method to simulate the influence scope of slope failure with a series of numerical treatments. Geographic Information System (GIS) platform and C# programming were adopted to build the model of the terrain details and features of the slope using SPH particles. At the same time the arrangement of boundary particles in the model were improved. Finally, a program that can automatically generate the data of landslide particles for calculation and simulation was completed. The model and method were applied to the Oso landslide case in Washington state, USA and the simulation results were basically consistent with the data collected from the field.It is verified that the SPH method and the model can be used to simulate the process and influence scope of slope failure.

8 Research on resistance imaging constraint inverse problem in concrete defect detection

YU Jiagan , CHEN Zhijun , ZHOU Xiaoyong , PAN Xun

2019, 42(5):66-75. DOI: 10.11835/j.issn.1000-582X.2019.05.008

[Abstract](711) [HTML](801) [PDF 6.44 M](939)

Abstract:
Electrical Resistance Tomography (ERT) is a kind of medical imaging technology taking the body's conductivity distribution as the target.With the advantages of visualization, low cost and no damage, it has broad prospects in the field of concrete defect detection. Based on the basic principle of resistance imaging, the MATLAB platform is used to compile the ERT forward and the inverse problem program. According to the electrical characteristics of concrete matrix and defects, we apply constraints to the algorithm and interfere with Newton-Raphson iteration process in inverse operation by modifying initial values, so as to improve the computational stability and image resolution of ERT posed inverse problem. The results show that the ERT constraint algorithm can reduce the number of iterations and eliminate imaging artifacts to a large extent, thus improving acuity and realizing relatively accurate nondestructive detection of concrete defects.

9 Improved dolphin swarm algorithm based on information entropy and its truss optimization

LI Yancang , WANG Xu

2019, 42(5):76-85. DOI: 10.11835/j.issn.1000-582X.2019.05.009

[Abstract](784) [HTML](1157) [PDF 1.55 M](1066)

Abstract:
Aiming at the disadvantage that basic dolphin swarm algorithm is easy to fall into local optimum, an improved dolphin swarm algorithm based on information entropy is proposed. The algorithm measures the uncertainty of dolphin swarm search phase by information entropy, controls the selection probability of search phase, reduces blind search, and overcomes the shortcomings of local optimum and premature convergence in the search phase of basic dolphin swarm algorithm. The improved algorithm is applied to the optimization of truss structure and compared with other algorithms. It is proved that the improved algorithm has better performance in convergence speed and optimization accuracy. It is applied to optimum design of truss structure, and provides an effective method for optimum design of structure.

10 Outage probability analysis of cognitive two-way cooperative relay networks with energy harvesting

LUO Yi , SHI Ronghua , DONG Jian , TANG Kun , FENG Zhuohui

2019, 42(5):86-94. DOI: 10.11835/j.issn.1000-582X.2019.05.010

[Abstract](826) [HTML](427) [PDF 1.04 M](870)

Abstract:
To extend the life time and reduce the outage probability of cognitive relay networks, a cognitive two-way relay networks with power-beacon (PB) assisted energy harvesting and multiple primary receivers was proposed, and the outage performance of underlay cognitive multiple relays secondary networks adopting decode-and-forward mode and opportunistic relay selection strategy was studied, wherein the transmission power of secondary users was subject to the energy harvested from PB and the interference constraint from the primary receivers. The exact outage probability of secondary networks for Rayleigh block fading channel was derived, and the results indicated that the outage probability was monotonically decreasing with the increase of PB's transmission power or primary network's interference constraint. Furthermore, the asymptotic outage probability of secondary networks with or without interference constraint was derived, and the outage saturation phenomenon, the impact of PB's location on outage probability, and the relationship between outage probability and the number of primary receivers and relays, secondary networks' end-to-end capacity and energy harvesting ratio were studied. Simulation results validated the theoretical derivation.

11 Video fusion based on guided filter and weighted two-dimensional PCA

XU Dan , GONG Peiqi , GUO Songtao , WANG Ying , YAO Jing

2019, 42(5):95-107. DOI: 10.11835/j.issn.1000-582X.2019.05.011

[Abstract](651) [HTML](768) [PDF 4.33 M](757)

Abstract:
Visible videos can mainly provide texture information, whereas infrared videos provide hidden hot information. The fusion of both kinds of videos can generate higher quality video viewing experience. However, due to the limited mobile device resources, the complicated video processing tasks are off loaded to the more powerful cloudlet with more sufficient resources (computing, storage, and battery resources) to be performed. In this paper the inter-frame redundancy detection algorithm based on the mean hash is proposed, and the video frames after redundancy removal are transmitted to the cloudlet for processing. The video fusion algorithm based on the guided filter and the weighted two-dimensional principal component analysis (W2DPCA) is proposed. The video frames to be fused are first divided into base layer and detail layer using guided filter. Then, the base layers of visible frame and infrared frame are fused by the improved adaptive W2DPCA. Finally, the fused frame is acquired by combination of the fusional base layer and the reserved detail layer. Experiment results show that the redundancy detection method minimizes the amount of redundant data transmission in cloudlets and reduces the energy consumption of mobile devices. Compared with the existing methods, the fused frame obtained by the video fusion algorithm in this paper has more mutual information and higher structural similarity to the original frame, and the fusion result also has higher overall standard deviation and peak signal-to-noise ratio thus having better overall integration effect.

12 Design and practice of an efficient digital filter algorithm based on S7-1200 AD Sampling

CHEN Mingfang , LIU Jinxin , ZHANG Yongxia , GE Tianyou , ZANG Jiaxiu , CHEN Hao

2019, 42(5):108-118. DOI: 10.11835/j.issn.1000-582X.2019.05.012

[Abstract](1009) [HTML](1454) [PDF 2.08 M](1815)

Abstract:
In the AD sampling process of Siemens S7-1200PLC, sampling data jitter is caused by external interference and sensor sampling data disturbance. Based on the principle of Least Mean Square (LMS), an improved weighted average digital filtering algorithm is designed in this paper. In 1200PLC, the corresponding filter algorithm program is compiled by SCL language to filter the sampled data of AD. An experiment is done on the AD sampling under a strong interference environment, and the sampling data is stable and accurate, proving that the digital filtering algorithm is efficient and reliable.

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