Study on the Tensile Properties and Application of Gravelly Soil Reinforced by Polypropylene Fiber

Zhitao Zhang,Enyue Ji,Zhongzhi Fu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.8

Incorporating fibers into gravelly soil is an effective method to prevent the core wall of high earth core rockfill dams (ECRDS) from cracking. In this study, a new type of soil tensile device was used to carry out tensile tests on gravelly soil with different gravel contents and fiber contents. The test results show that as the gravel content increases from 0% to 50%, the improvement in tensile strength decreases from 48.9% to 6.4%, which means the increase in gravel content reduces the improvement in tensile strength significantly. The ultimate tensile strain, tensile strength, and post-peak tensile strength of fiber-reinforced gravelly soil are positively correlated with the fiber content. Combined with the Scanning electron microscopy (SEM) results, the reinforcement effect of the three types of fiber interfaces on the gravel soil is qualitatively analyzed, and the microscopic mechanism of the improvement of the tensile strength of fiber-reinforced gravelly soil is revealed. The energy absorption capacity (EAC) results showed that the lower the gravel content in the soil, the higher the degree of improvement in the EAC value. In practical application, it is recommended to use gravel soil with low gravel content and high fiber content. Finally, a regression model considering the gravel content and fiber content was proposed for fast predicting the tensile strength of the soil. The related results can provide references for the anti-cracking design of the core wall of high ECRDS.

Micro-gap DBD Plasma and Its Applications

( Zhitao Zhang ),( Cheng Liu ),( Mindi Bai ),( Bo Yang ),( Cheng Qi Mao ) 한국동굴학회 2006 동굴 Vol.76 No.-

The Dielectric Barrier Discharge (DBD) is a nonequilibrium gas discharge that is generated in the space between two electrodes, which are separated by an insulating dielectric layer. The dielectric layer can be put on either of the two electrodes or be inserted in the space between two electrodes. If an AC or pulse high voltage is applied to the electrodes that is operated at applied frequency from 50Hz to several MHz and applied voltages from a few to a few tens of kilovolts rms, the breakdown can occur in working gas, resulting in large numbers of micro-discharges across the gap, the gas discharge is the so called DBD. Compared with most other means for nonequilibrium discharges, the main advantage of the DBD is that active species for chemical reaction can be produced at low temperature and atmospheric pressure without the vacuum set up, it also presents many unique physical and chemical process including light, heat, sound and electricity. This has led to a number of important applications such as ozone synthesizing, UV lamp house, CO2 lasers, et al. In recent years, due to its potential applications in plasma chemistry, semiconductor etching, pollution control, nanometer material and large area flat plasma display panels, DBD has received intensive attention from many researchers and is becoming a hot topic in the field of non-thermal plasma.

TRANSCRIPTOMIC PROFILING ANALYSIS OF THE ENDANGERED CHINESE GIANT SALAMANDER (Andrias davidianus)

Zhitao Qi,Qihuan Zhang,Zisheng Wang,Gao Qiao,Jie Zhou,Jason Holland,Qian Gao 한국수산과학회 양식분과 2015 한국수산과학회 양식분과 학술대회 Vol.2015 No.5

Surface Parameter Measurement of Braided Composite Preform Based on Faster R-CNN

Zhitao Xiao,Lei Pei,Lei Geng,Ying Sun,Fang Zhang,Jun Wu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.3

Pitch length and surface braiding angle are two important parameters of braided composite preforms. In this paper,a method based on Faster R-CNN is proposed to measure the two parameters. First, after image acquisition, a fabric imagedatabase including initial cropped images, augmented images, and target images is established. Then, the target images areclassified into four categories according to the gray change characteristics. Third, a Faster R-CNN fabric detection model istrained on the fabric image database. Fourth, targets are detected by the trained network, and corners are detected based onthe detected targets. Finally, pitch lengths and surface braiding angles are measured based on the detected corners. Experimental results show that the proposed method achieves the automatic measurement of pitch lengths and surfacebraiding angles of 2D and 3D braided composite preforms with high accuracy.

Closed-Loop Bifurcation Analysis for a Novel Moving Mass Flight Vehicle

Zhitao Liu,Changsheng Gao,Jianqing Li,Wuxing Jing 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.4

In this paper, nonlinear dynamics properties regarding a novel moving mass flight vehicle with large mass ratio are investigated based on bifurcation theory and continuation methods. Of particular interest is the impact of variation of command angle-of-attack and moving mass parameters on the controlled system. The nonlinear longitudinal dynamics model is established and the controller is designed using Immersion and Invariance method. Bifurcation analysis is conducted both from the prospective of static bifurcation and dynamical bifurcation, results of the closed-loop system are compared with the uncontrolled case. Numerical results obtained from bifurcation diagrams indicate that although the introduction of control system is capable of eliminating unstable regions caused by the variation of moving mass parameters, the change of command angle-of-attack still lead to Hopf bifurcation. Furthermore, analysis of limit cycle branch reveals the consecutive birth of Limit Point of Cycle bifurcation (LPC), then based on which a more detailed nonlinear dynamics process of the closed-loop system is analyzed.

A numerical study of a confined turbulent wall jet with an external stream

Zhitao Yan,Yongli Zhong,Xu Cheng,Rory P. McIntyre,Eric Savory 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.2

Wall jet flow exists widely in engineering applications, including the simulation of thunderstorm downburst outflows, and has been investigated extensively by both experimental and numerical methods. Most previous studies focused on the scaling laws and self-similarity, while the effect of lip thickness and external stream height on mean velocity has not been examined in detail. The present work is a numerical study, using steady Reynolds-Averaged Navier Stokes (RANS) simulations at a Reynolds number of 3.5 × 104, of a turbulent plane wall jet with an external stream to investigate the influence of the wall jet domain on downstream development of the flow. The comparisons of flow characteristics simulated by the Reynolds stress turbulence model closure (Stress-omega, SWRSM) and experimental results indicate that this model may be considered reasonable for simulating the wall jet. The confined wall jet is further analyzed in a parametric study, with the results compared to the experimental data. The results indicate that the height and the width of the wind tunnel and the lip thickness of the jet nozzle have a great effect on the wall jet development. The top plate of the tunnel does not confine the development of the wall jet within 200b of the nozzle when the height of the tunnel is more than 40b (b is the height of jet nozzle). The features of the centerline flow in the mid plane of the 3D numerical model are close to those of the 2D simulated plane wall jet when the width of the tunnel is more than 20b.

Research on the application of 3D simulation technology in Maritime Regulatory

Hao Zhitao,Yang Zhuoyi,Jiang Shiyuan,Liang Hongguang,Zhou Fenglei 국제이네비해양경제학회 2022 International Journal of e-Navigation and Maritime Vol.19 No.1

The progress of science and technology has driven the development of the society, and the application of threedimensional simulation technology in all walks of life has greatly improved people's life. Maritime affairs is an important part of comprehensive transportation. The improvement of maritime supervision and service level is conducive to the construction of domestic first-class economic law enforcement system and international leading maritime management institutions. Now the application of 3D simulation technology to maritime supervision is studied, aiming to improve the quality and efficiency of supervision, make maritime supervision more convenient and have further guarantee. Maritime supervision of ship environment is often more troublesome than personnel management. In the process of monitoring and control, many uncontrollable environmental factors greatly increase the difficulty of supervision, among which the port environment is more complex, which is a difficulty of monitoring and control in maritime supervision. This paper uses MapInfo Professional, Win Topo, Multigen Creator and other operating software to construct the Qingdao port visual simulation environment. The port topographic cloud map of Qingdao Port was captured, and the collected image information was converted into data through MapInfo Professional and Win Topo software, and then modeled by Multigen Creator software. After completing the general terrain outline, the established simulation scene was made more realistic and realistic through some detail processing and optimization means. By describing the establishment of 3D simulation terrain in Qingdao Port, the application status of the simulation technology in ship environment and port management is reflected, which provides a reference for the deeper application of 3D simulation technology in maritime supervision.

A numerical study of a confined turbulent wall jet with an external stream

Yan, Zhitao,Zhong, Yongli,Cheng, Xu,McIntyre, Rory P.,Savory, Eric Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.27 No.2

Wall jet flow exists widely in engineering applications, including the simulation of thunderstorm downburst outflows, and has been investigated extensively by both experimental and numerical methods. Most previous studies focused on the scaling laws and self-similarity, while the effect of lip thickness and external stream height on mean velocity has not been examined in detail. The present work is a numerical study, using steady Reynolds-Averaged Navier Stokes (RANS) simulations at a Reynolds number of $3.5{\times}10^4$, of a turbulent plane wall jet with an external stream to investigate the influence of the wall jet domain on downstream development of the flow. The comparisons of flow characteristics simulated by the Reynolds stress turbulence model closure (Stress-omega, SWRSM) and experimental results indicate that this model may be considered reasonable for simulating the wall jet. The confined wall jet is further analyzed in a parametric study, with the results compared to the experimental data. The results indicate that the height and the width of the wind tunnel and the lip thickness of the jet nozzle have a great effect on the wall jet development. The top plate of the tunnel does not confine the development of the wall jet within 200b of the nozzle when the height of the tunnel is more than 40b (b is the height of jet nozzle). The features of the centerline flow in the mid plane of the 3D numerical model are close to those of the 2D simulated plane wall jet when the width of the tunnel is more than 20b.

Micro-gap DBD Plasma and Its Applications

Zhang, Zhitao,Liu, Cheng,Bai, Mindi,Yang, Bo,Mao, Chengqi The Speleological Society 2006 동굴 Vol.76 No.-

The Dielectric Barrier Discharge (DBD) is a nonequilibrium gas discharge that is generated in the space between two electrodes, which are separated by an insulating dielectric layer. The dielectric layer can be put on either of the two electrodes or be inserted in the space between two electrodes. If an AC or pulse high voltage is applied to the electrodes that is operated at applied frequency from 50Hz to several MHz and applied voltages from a few to a few tens of kilovolts rms, the breakdown can occur in working gas, resulting in large numbers of micro-discharges across the gap, the gas discharge is the so called DBD. Compared with most other means for nonequilibrium discharges, the main advantage of the DBD is that active species for chemical reaction can be produced at low temperature and atmospheric pressure without the vacuum set up, it also presents many unique physical and chemical process including light, heat, sound and electricity. This has led to a number of important applications such as ozone synthesizing, UV lamp house, CO2 lasers, et al. In recent years, due to its potential applications in plasma chemistry, semiconductor etching, pollution control, nanometer material and large area flat plasma display panels, DBD has received intensive attention from many researchers and is becoming a hot topic in the field of non-thermal plasma.

A Robust Approach for Overlay Text Localization and Extraction in Complex Video Scene

Jingfan Tang,Zhitao Li,Xingqi Wang,Ming Jiang,Ziyang Li 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.10

Overlay text in video carries important semantic clues for video information retrieval and summarization. In this paper, we propose a robust method that is able to accurately locate text lines and extract text even in complex video scene. In the text localization stage, this paper adopts the method based on corner point. First, corner detection is used to extract corners as text features from video frames. Then multi-layer filtering mechanism (MLFM) is used to locate the text lines, which consists of corners clustering, corners horizontal projection, background filtering and heuristic rules. This MLFM can effectively remove the isolated corners, locate the text lines accurately and remove the background or pseudo text lines automatically. In the text extraction stage, this paper proposed a twice binarization method that combines with polarity judgment on image. The polarity judgment was used as a guide to adjust the first binarization threshold when we perform the first binarization. After the first binarization, a main proportion of the image has been processed, and the rest will be processed by the second binarization. Experimental results show that this approach can fast and robustly locate text lines and extract text in video even under complex background.