Stress Field of Structures with Internal Cracks by 3D-ILC Technology: Experimental and Numerical Analysis

Haijun Wang,Haitang Qi,Xuhua Ren,Lei Tang,Qianqian Dong 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.1

Great achievements have been made regarding the stress field in the two-dimensional state, however the study of three-dimensional stress field visualization has still not been comprehensively examined. The model with internal cracks was prepared by the laser-medium interaction (3D-ILC), and with the aid of the photoelastic test technology, it visually showed the distribution characteristics of the stress field inside the rock with defects under the three-point bending test method. Primarily, based on the two-dimensional and three-dimensional stress optics law, the isometric fringes were converted into phase differences or optical path differences to visualize the stress field. Moreover, transparent glass, which had better transparency and brittleness closer to real rock was selected as the specimen material. Internal cracks changed the stress fringe distribution of the specimen, and the combination of 3D-ILC technology and photoelasticity provided a new way to visualize the three-dimensional stress field of brittle materials with internal cracks. Through the secondary development and utilization of ABAQUS finite element analysis software, the internal stress fields of brittle solid materials with horizontal internal cracks were visualized. Accurate characterization of the three-dimensional stress field of brittle solid materials has been a long-term goal pursued by researchers in the field of fracture, and it is also the basis and key to solving many practical engineering problems such as design, safety analysis and evaluation.

Determination and Variation of Core Bacterial Community in a Two- Stage Full-Scale Anaerobic Reactor Treating High-Strength Pharmaceutical Wastewater

( Haijun Ma ),( Lin Ye ),( Haidong Hu ),( Lulu Zhang ),( Lili Ding ),( Hongqiang Ren ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.10

Knowledge on the functional characteristics and temporal variation of anaerobic bacterial populations is important for better understanding of the microbial process of two-stage anaerobic reactors. However, owing to the high diversity of anaerobic bacteria, close attention should be prioritized to the frequently abundant bacteria that were defined as core bacteria and putatively functionally important. In this study, using MiSeq sequencing technology, the core bacterial community of 98 operational taxonomic units (OTUs) was determined in a twostage upflow blanket filter reactor treating pharmaceutical wastewater. The core bacterial community accounted for 61.66% of the total sequences and accurately predicted the sample location in the principal coordinates analysis scatter plot as the total bacterial OTUs did. The core bacterial community in the first-stage (FS) and second-stage (SS) reactors were generally distinct, in that the FS core bacterial community was indicated to be more related to a higherlevel fermentation process, and the SS core bacterial community contained more microbes in syntrophic cooperation with methanogens. Moreover, the different responses of the FS and SS core bacterial communities to the temperature shock and influent disturbance caused by solid contamination were fully investigated. Co-occurring analysis at the Order level implied that Bacteroidales, Selenomonadales, Anaerolineales, Syneristales, and Thermotogales might play key roles in anaerobic digestion due to their high abundance and tight correlation with other microbes. These findings advance our knowledge about the core bacterial community and its temporal variability for future comparative research and improvement of the two-stage anaerobic system operation.

A Carrier Communication Channel Modeling Of Marine Electromagnetic Exploration System Based On Multi Conductor Transmission Line Theory

Xiguo Ren,Yiming Zhang,Haijun Tao,Zhihui Zeng,Jianzhi Ding 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.10

Subsea communication system is a key component of marine electromagnetic exploration system. In subsea communication system, only the power line channel model is fully studied, it could help to achieve high-speed and reliable power line carrier communication. In this paper, a channel model is established by using the theory of multi conductor transmission. The single Pi structure, double Pi structure and T structure cable model have been simulated through the Spice. The accuracy of single Pi structure model was verified by measurement and simulation. It provides a guiding role for the whole communication system.

A Method for The Evaluating Performance of High Power Electromagnetic Transmitter

Xiguo Ren,Yiming Zhang,Haijun Tao,Xuezheng Zhu 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.9

In recent years, the Earth's resources have the obvious contradiction between supply and demand. Electromagnetic has become the most effective means for prospecting geological structure. In the electromagnetic method, the transmission frequency has a significant impact on the reception and subsequent analysis. Therefore, the distribution and stability of the actual transmission frequency is an extremely important factor in judging for the transmitter. This paper presents an assessment method of the transmitting the performance parameters for the high-power electromagnetic transmitter. This method can intuitively observe the actual transmission frequency by the position machine when the transmitter is working. And the frequency distribution and stability could be got by Matlab. After a large number of comparative field trials, this method is verified which could quickly and efficiently get the frequency distribution and stability of the actual transmitting. This method could provide a basis for future inversion calculation and have a guiding role for the transmitter optimization.

Calculation of Leakage Inductance of Integrated Magnetic Transformer with Separated Secondary Winding Used in ZVS PSFB Converter

Tian Jiashen,Zhang Yiming,Ren Xiguo,Wang Xuhong,Tao Haijun 한국자기학회 2016 Journal of Magnetics Vol.21 No.4

A novel zero voltage switching (ZVS) phase shift full bridge (PSFB) converter used in geophysical exploration is proposed in this paper. To extend the ZVS ranges and increase power density of the converter, external inductor acting as leakage inductance is applied and integrated into the integrated magnetic (IM) transformer with separated secondary winding. Moreover, the loss of ZVS PSFB converter is also decreased. Besides, the analysis and accurate prediction methodology of the leakage inductance of the IM transformer are proposed, which are based on magnetic energy and Lebedev. Finally, to verify the accuracy of analysis and methodology, the experimental and finite element analysis (FEA) results of IM transformer and 40 kW converter prototypes are given.

Step-by-step identification of industrial robot dynamics model parameters and force-free control for robot teaching

Binrui Wang,Junwei Fang,Shunan Qi,Ling Wang,Xiaolong Liu,Haijun Ren 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

In order to solve the problem of lack of flexibility in direct teaching of industrial robots under complex working conditions, dynamic inertia term compensation is combined with the traditional force-free control algorithm to reduce the traction in the teaching process in this paper. Firstly, considering the multi-dimensional, strongly nonlinear and multi-parameter characteristics of the 6-DOF manipulator dynamic model, a step-by-step parameters identification method based on genetic algorithm is proposed. This method can effectively reduce the computational complexity and improve the optimization speed of industrial robot dynamic model identification. Secondly, based on the internal torque analysis of industrial robot joints, a forcefree compensation control algorithm based on the torque control is designed. Finally, the effectiveness of the step-by-step robot dynamic model parameter identification method is verified by a traction teaching experiment. In the verification experiment, the relative error rate between the predicted torque and the actual torque calculated from the identification results is 1.64 % to 5.99 %. After increasing the inertia term compensation, the traction force of the teaching process is reduced by 28.6 %. The experimental results show that the identification result is more accurate, and the proposed force-free control algorithm significantly improves the compliance of the teaching process.