Panting Fatigue of Trapezoidal Corrugated Steel Webs with Mixed-Mode Cracks

Zhiyu Wang,Xiafang Zhou,Zifeng Liu 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.2

Trapezoidal corrugated steel webs under panting fatigue are represented by repeated cyclical out-of-plane defl ections of their subpanel with mixed-mode cracks. Compared to stiff ened fl at webs, notable fatigue crack formation could take place along with local defl ection. Fatigue tests were conducted for nine composite girders with slender webs and varied corrugation dimensions. Nearly all test girders showed notable local and interactive shear buckling at the corrugated web panel and the panting fatigue cracks are formed under repeated cyclical defl ection while the compression and tension fl anges remain intact. Fatigue cracks are initiated at the junction between the vertical (longer) edge of the subpanel and the boundary of the out-of-plane defl ection region. The crack propagation paths appear to deviate from the original vertical edge due to buckling induced out-of-plane defl ection under mixed-mode stress condition. The test results demonstrate that the Category B’ and Category E suggested by the AASHTO LRFD bridge fatigue design provisions related to the principal stress range and the nominal membrane shear stress range respectively can be considered for the prediction of the fatigue life of trapezoidal Corrugated steel webs in test girders. An appropriate allowance of both the shear stress along the vertical web edge and tension stress from the diagonal plastifi ed tension band is given for the mixed-mode stress intensity factor. The proposed fatigue life prediction allowing for mixed-mode crack growth mostly compares well with test results and its further improvement for the case with higher web panel slenderness ratio is discussed.

Fatigue Strength Evaluation of Welded Structural Details in Corrugated Steel Web Girders

Zhiyu Wang,Lianfei Tan,Qingyuan Wang 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.4

Fatigue strength evaluation of welded structural details is of practical significance in the design of corrugated steel webgirders in highway bridges and industrial structures. In this paper, the fatigue strengths of corrugated steel web girders withseveral welded structural details and welding methods are analytically examined by fatigue tests of corrugated web beams andsmall-size welded joints. The stress concentration & distribution characteristics of corrugated web beams were analysed usingfinite element analysis. The beam test results showed that the structure with scallops or notches in the flange has lower fatiguestrength and that with butt joints is prone to suffer from shear crack on the corrugated web. Within the inside range of thescallop, the stress concentration becomes greater with the increase of scallop radius and the tension flange contributessignificantly to the bending capacity of corrugated steel web beams. The tests for small-size welded joints indicated theirapplicability in the analysis and prediction of S-N relationship of the test corrugated steel web beams. Finally, the fatigue crackpropagation lives of weld joints were compared with those of test corrugated steel web beams with respect to related designCategories of the AASHTO LRFD Bridge Design Specifications.

Visual Tracking Using Improved Multiple Instance Learning with Co-training Framework for Moving Robot

( Zhiyu Zhou ),( Junjie Wang ),( Yaming Wang ),( Zefei Zhu ),( Jiayou Du ),( Xiangqi Liu ),( Jiaxin Quan ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.11

Object detection and tracking is the basic capability of mobile robots to achieve natural human-robot interaction. In this paper, an object tracking system of mobile robot is designed and validated using improved multiple instance learning algorithm. The improved multiple instance learning algorithm which prevents model drift significantly. Secondly, in order to improve the capability of classifiers, an active sample selection strategy is proposed by optimizing a bag Fisher information function instead of the bag likelihood function, which dynamically chooses most discriminative samples for classifier training. Furthermore, we integrate the co-training criterion into algorithm to update the appearance model accurately and avoid error accumulation. Finally, we evaluate our system on challenging sequences and an indoor environment in a laboratory. And the experiment results demonstrate that the proposed methods can stably and robustly track moving object.

Thermal Gradients and Their Effects on Bending Behavior of Composite Girders with Trapezoidal Profiled Webs

Zhiyu Wang,Qifei Wang,Peiyan Huang,Guowen Yao,Rui Yang,Zhanbiao Chen 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

Thermal gradient may have significant effect on the bending behavior of the composite girderwith trapezoidal profiled web. To quantify such an effect on the thermos-strain action,temperature elevation test and finite element modeling were carried out on the specimenswith the flange sensitive to bending and the web possessed adequate buckling resistance. Thecross-sectional thermal gradients for different location away from the middle of span weremeasured using thermocouples and correlated using Boltzmann sigmoid equations. Theapplicability of finite element model was validated against experiments in terms of thedistribution of thermal strain, deflections and axial strains. The axial strain distributions acrossthe flange width and along the longitudinal direction of girder were analyzed in details. Thetesting and finite element modeling results showed that, the deflections with applied loadsnear the middle of span subjected to maximum bending moment are notably influenced bythe increase of thermal gradient. The maximum axial strains at the upper surface and thelower surface of the bottom flange are obviously influenced by the temperature, especially forthe girders with relatively high span-depth ratios or thicker flanges. The thermal gradient at theupper surface of the bottom flange is relatively higher than that on lower surface for every10oC rise of temperature which meant that the upper surface of the bottom flange connectingtrapezoidal profiled webs is more sensitive to thermo-elastic action.

Assessment of diffusion tensor image quality across sites and vendors using the American College of Radiology head phantom

Wang, Zhiyue J.,Seo, Youngseob,Babcock, Evelyn,Huang, Hao,Bluml, Stefan,Wisnowski, Jessica,Holshouser, Barbara,Panigrahy, Ashok,Shaw, Dennis W.W.,Altman, Nolan,McColl, Roderick W.,Rollins, Nancy K. John Wiley and Sons Inc. 2016 Journal of applied clinical medical physics Vol.17 No.3

<P>The purpose of this study was to explore the feasibility of assessing quality of diffusion tensor imaging (DTI) from multiple sites and vendors using American College of Radiology (ACR) phantom. Participating sites (Siemens (n=2), GE (n=2), and Philips (n=4)) reached consensus on parameters for DTI and used the widely available ACR phantom. Tensor data were processed at one site. <SUB>B0</SUB> and eddy current distortions were assessed using grid line displacement on phantom Slice 5; signal‐to‐noise ratio (SNR) was measured at the center and periphery of the b=0 image; fractional anisotropy (FA) and mean diffusivity (MD) were assessed using phantom Slice 7. Variations of acquisition parameters and deviations from specified sequence parameters were recorded. Nonlinear grid line distortion was higher with linear shimming and could be corrected using the 2nd order shimming. Following image registration, eddy current distortion was consistently smaller than acquisition voxel size. SNR was consistently higher in the image periphery than center by a factor of 1.3–2.0. ROI‐based FA ranged from 0.007 to 0.024. ROI‐based MD ranged from 1.90×<SUP>10−3</SUP> to 2.33×<SUP>10−3</SUP><SUP>mm2</SUP>/s(median=2.04×<SUP>10−3</SUP><SUP>mm2</SUP>/s). Two sites had image void artifacts. The ACR phantom can be used to compare key quality measures of diffusion images acquired from multiple vendors at multiple sites.</P><P>PACS number(s): 87.57.‐s, 87.19.lf</P>

Nanofire and scale effects of heat

Zhiyu Hu,Sebastiaan A. Meijer,Qiuchen Wang,Erzhen Mu,Gang Yang,Zhimao Wu 나노기술연구협의회 2019 Nano Convergence Vol.6 No.5

Combustion is a chemical reaction that emits heat and light. Nanofire is a kind of flameless combustion that occurs on the micro–nano scale. Pt/Al2O3 film with a thickness of 20 nm can be prepared as a catalyst by micro–nano processing. When the methanol-air mixture gas passes through the surface of the catalyst, a chemical reaction begins and a significant temperature rise occurs in the catalyst region. Compared to macroscopic combustion, Nanofire has many special properties, such as large temperature gradients, uniform temperature distribution, and fast temperature response. The large temperature gradient is the most important property of Nanofire, which can reach 1330 K/mm. Combined with thermoelectric materials, it can realize the efficient conversion of chemical energy to electric energy. Nanoscale thickness offers the possibility of establishing thermal gradient. On the other hand, large thermal gradient has an effect on the transport properties of phonons and electrons in film materials. From these we can get the scale effects of heat. This article will provide an overview of the preparation, properties and applications of Nanofire, and then a comprehensive introduction to the thermal scale and thermal scale effects.

Robot Manipulator Visual Servoing via Kalman Filter- Optimized Extreme Learning Machine and Fuzzy Logic

Zhiyu Zhou,Yanjun Hu,Jiangfei Ji,Yaming Wang,Zefei Zhu,Donghe Yang,Ji Chen 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.8

Visual servoing (VS) based on the Kalman filter (KF) algorithm, as in the case of KF-based image-based visual servoing (IBVS) systems, suffers from three problems in uncalibrated environments: the perturbation noises of the robot system, error of noise statistics, and slow convergence. To solve these three problems, we use an IBVS based on KF, African vultures optimization algorithm enhanced extreme learning machine (AVOA-ELM), and fuzzy logic (FL) in this paper. Firstly, KF online estimation of the Jacobian matrix. We propose an AVOA-ELM error compensation model to compensate for the sub-optimal estimation of the KF to solve the problems of disturbance noises and noise statistics error. Next, an FL controller is designed for gain adaptation. This approach addresses the problem of the slow convergence of the IBVS system with the KF. Then, we propose a visual servoing scheme combining FL and KF-AVOA-ELM (FL-KF-AVOA-ELM). Finally, we verify the algorithm on the 6-DOF robotic manipulator PUMA 560. Compared with the existing methods, our algorithm can solve the three problems mentioned above without camera parameters, robot kinematics model, and target depth information. We also compared the proposed method with other KF-based IBVS methods under different disturbance noise environments. And the proposed method achieves the best results under the three evaluation metrics.

Extraction of lignocellulose nanocrystals (LCNC) from oak wood for fabrication of nanocomposite film

( Wang Fei ),김태현,박승현,민병용,김태연,( Tao Zhiyu ) 한국공업화학회 2023 한국공업화학회 연구논문 초록집 Vol.2023 No.1

Random vector functional link network with L21 norm regularization for robot visual servo control with feature constraint

Zhiyu Zhou,Jiusen Guo,Yaming Wang,Zefei Zhu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.9

Uncalibrated visual servoing control still encounters some challenges, such as calculating the interaction matrix with less cost and keeping the current image features within a camera’s field of view (FOV) in a noisy system environment. To solve these problems, we propose a new control method that uses a random vector functional link network with L21 norm regularization to calculate the interaction matrix and further estimate it with a robust information filter (RIF). L21 norm regularization can deal with the global sparsity of input weights and reduce the inherent complexity of a model. The RIF limits noise variance within a certain range to reduce the influence of uncertain noise on the servoing task. We also design a method that reacts to the control law in accordance with the coordinates of image features. It can adjust running speed in real time and keep image features within a camera’s FOV. We apply this method to a six-degrees-of-freedom eye-in-hand manipulator, and several simulations are performed. Simulation results show that the proposed algorithm performs well in the task and achieves good performance in terms of noise resistance. Image features barely escape from the camera’s FOV through the proposed constraint method.

Optimization for Remote Monitoring Terrestrial Petroleum Pipeline Cathode Protection System Using Graded Network

Pingting Liu,Zhiyu Huang,Shihong Duan,Zikang Wang,Jie He 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.6

Method of cathode protection is employed to slow down the corrosion of terrestrial pipe. This paper aims to develop a system to monitor the terrestrial pipe cathode protection equipment to wholly track the operation status of buried pipe timely. The monitoring system integrates technology of wireless sensor networks, GPRS network and Internet not only to collect the cathode potential data in time and realize remote data transmission but also to regulate the guard mode of cathode protection on demand. Optimization mechanisms are adopted to effectively lower the energy assumption and to ensure data transmission reliability, from architecture design, selection of power saving hardware components, implementation of reliable network traffic mechanism including hierarchical network topology with least-complexity cluster head shift strategy, TDMA protocol with auto-adaptive resending scheme, work-on-duty with radio-awaken mechanism and so on. Trial running of the system has published good results with 96% or higher success ratio of data transmission, low power saving and power balance. In all, this system can meet the requirements of timely detecting physical malfunction of terrestrial pipeline and controlling field monitoring system on demand.