scholarly journals Ultrasonic Detection Method for Grouted Defects in Grouted Splice Sleeve Connector Based on Wavelet Pack Energy

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1642 ◽  
Author(s):  
Zuohua Li ◽  
Lilin Zheng ◽  
Chaojun Chen ◽  
Zhili Long ◽  
Ying Wang
Keyword(s):  
Detection System ◽  
Wavelet Packet ◽  
Precast Concrete ◽  
Ultrasonic Method ◽  
Complex Structure ◽  
Ultrasonic Detection ◽  
Concrete Members ◽  
Negative Effect ◽  
Group A ◽  
Ultrasonic Parameters

Grouted splice sleeve (GSS) connectors are mainly used in precast concrete structures. However, errors in manual operation during construction cause grouted defects in the GSS connector, which can lead to a negative effect on the overall mechanical properties of the structures. Owing to the complex structure of precast concrete members with a GSS connector, it is difficult to detect grouted defects effectively using traditional ultrasonic parameters. In this paper, a wavelet packet analysis algorithm was developed to effectively detect grouted defects using the ultrasonic method, and a verified experiment was carried out. Laboratory detection was performed on the concrete specimens with a GSS connector before grouting, in which the grouted defects were mimicked with five sizes in five GSS connectors of each specimen group. A simple and convenient ultrasonic detection system was developed, and the specimens were detected. According to the proposed grouted defect index, the results demonstrated that when the grouted defects reached certain sizes, the proposed method could detect the grouted defects effectively. The proposed method is effective and easy to implement at a construction site with simple instruments, and so provides an innovative method for grouted defects detection of precast concrete members.

scholarly journals Invariant connections and invariant holomorphic bundles on homogeneous manifolds

2014 ◽  
Vol 12 (1) ◽  
pp. 1-13
Author(s):  
Indranil Biswas ◽  
Andrei Teleman
Keyword(s):  
Lie Group ◽  
Complex Structure ◽  
Differentiable Manifold ◽  
Equivalence Classes ◽  
Transitive Action ◽  
Isomorphism Classes ◽  
Finite Dimensional ◽  
Group A ◽  
Holomorphic Bundles ◽  
Invariant Gauge

AbstractLet X be a differentiable manifold endowed with a transitive action α: A×X→X of a Lie group A. Let K be a Lie group. Under suitable technical assumptions, we give explicit classification theorems, in terms of explicit finite dimensional quotients, of three classes of objects:equivalence classes of α-invariant K-connections on X α-invariant gauge classes of K-connections on X, andα-invariant isomorphism classes of pairs (Q,P) consisting of a holomorphic Kℂ-bundle Q → X and a K-reduction P of Q (when X has an α-invariant complex structure).

A Fuzzy DEMATAL Model Proposal for the Cause and Effect of the Fault Occuring in the Auxiliary Systems of the Ships' Main Engine

2018 ◽  
Vol Vol 160 (A2) ◽  
Author(s):  
A Balin ◽  
H Demirel ◽  
E Celik ◽  
F Alarcin
Keyword(s):  
Decision Making ◽  
Error Detection ◽  
Detection System ◽  
Causal Effect ◽  
Complex Structure ◽  
Fuel Oil ◽  
Fuzzy Dematel ◽  
Engine Room ◽  
Engine Failure ◽  
Main Engine

The ship engine room has a structure that meets a number of needs related to administrative conditions. Even if a simple mechanical error is considered to be the addition of human errors into the complex structure of the engine room, it can lead to undetected loss. How the causes and effects of the detected faults affect the system is as important as an effective fault detection system to detect the fault and take immediate action against any possible engine failure. This study reveals the causes of problems occurring in the main engine auxiliary systems including cooling, lubricating, cooling oil and fuel systems, and the extent of these problems affecting the system. While the Decision Making Trial and Evaluation Laboratory supports to identify and analyze the error detection of auxiliary systems with respect to causal effect relation diagram, fuzzy sets deal with the uncertainty in decision-making and human judgements through the DEMATEL. Therefore, fuzzy DEMATEL approach is applied to examine the causes and the weights of the faults and their relation to each other in the auxiliary systems. When we look at the result of the proposed approach, fuel oil pump failures has more impact on the all system and air cooler problems has the second highest place among the all errors.

Ultrasonic Detection Algorithm Research on the Damage Depth of Concrete after Fire

2011 ◽  
Vol 368-373 ◽  
pp. 2229-2234
Author(s):  
Jiang Tao Yu ◽  
Yuan Liu ◽  
Zhou Dao Lu ◽  
Peng Zhao
Keyword(s):  
Ultrasonic Method ◽  
Least Square Method ◽  
Detection Algorithm ◽  
Measured Data ◽  
Structural Member ◽  
Least Square ◽  
Propagation Time ◽  
Practical Application ◽  
Ultrasonic Detection ◽  
Damage Depth

To measure the depth of fire-damaged concrete by ultrasonic method, it was traditionally assumed that the concrete of the fire-damaged structural member could be simply classified into damaged layer and undamaged layer. Based on it, the damage depth can be calculated with a series of single-sided ultrasonic measured data. This method is simple and convenient but less accurate in the practical application. To improve the algorithm, hyperbola curves are adopted to simulate the varying of damage with depth in this paper. And parabolic curves are adopted to simulate the traces of ultrasonic wave in different measured distances. Therefore, the minimum propagation time can be obtained under different damage conditions. Through comparing the calculating results and measured data in different measured distances, the most likely damaged trend can be determined with least square method. At the end of this paper, examples are demonstrated to prove this algorithm feasible and more accurate than the traditional one.

Denoising and Defect Diagnosis of Material Ultrasonic Detection signal Based on Best Wavelet Packet Base

2012 ◽  
Vol 239-240 ◽  
pp. 52-56
Author(s):  
Xiao Ling Yan ◽  
Shi Yun Dong ◽  
Wang Long Wang ◽  
Bin Shi Xu
Keyword(s):  
Nondestructive Testing ◽  
Wavelet Packet ◽  
Steel Specimen ◽  
Ultrasonic Signal ◽  
Defect Size ◽  
New Method ◽  
Accurate Information ◽  
Ultrasonic Nondestructive Testing ◽  
Internal Defect ◽  
Ultrasonic Detection

The use of ultrasonic nondestructive testing of material internal defect，ultrasonic signal acquired at actual working spot usually includes large amount of noise.Extraction of the defect characteristic information will be influeced greatly if the ultrasonic signal is not effectively denoised. A new method based on best wavelet packet base is present to denoise and detect the ultrasonic signal. The superiority of new method is verified by simulation examples. Experiment of processing ultrasonic signal which comes from the 45 Steel specimen with flaws has been implemented. The accurate information that characterizes of defect size,location can be extracted from the processing result, the results show that the new method based on best wavelet packet base is in favor of enhancing the degree of accuracy for quantitatively analyzing the defect inside the material.

Design of the Control Circuit Based on FPGA for the Underwater Trash Detection System

2011 ◽  
Vol 201-203 ◽  
pp. 2414-2418
Author(s):  
Guo Ku Zhao ◽  
Qi Zhang
Keyword(s):  
High Speed ◽  
Analog Circuit ◽  
Detection System ◽  
Control Circuit ◽  
Echo Signal ◽  
Process Data ◽  
Ultrasonic Detection ◽  
Distance Information ◽  
High Speed Data ◽  
System Power

For the detection of underwater trashes, the ultrasonic detection system is a necessary deceive. In the traditional ultrasonic detection system, echo signal is generally processed by analog circuit, and only the distance information is obtained. In order to determine the distance and material of target, the amplitude of echo wave also need to be extracted, and FPGA is employed to control high-speed AD and process data. The design of control circuit based on FPGA is presented here. The control circuit includes modules of clock, high-speed data processing, communication and transmitting control. On the basis of the system design, simulation, implementation, the system experiments are completed. The results show: the functions of the control circuit based on FPGA are implemented correctly, but the system power consumption needs to be reduced more.

Case Studies of Seismic Vibration Control of Civil Structures Using Shape Memory Alloys

2011 ◽  
Vol 243-249 ◽  
pp. 5427-5434
Author(s):  
Hui Qian ◽  
Hong Nan Li ◽  
Di Cui ◽  
Huai Chen
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Vibration Control ◽  
Case Studies ◽  
Precast Concrete ◽  
Reinforced Concrete Beams ◽  
Seismic Vibration ◽  
Concrete Members

Shape memory alloys (SMAs) are unique class materials that have the ability to undergo large deformations, while returning to their undeformed shape through either the applications of heat (SME) or removal of stress (SE). The unique properties lead to their wide applications in the biomedical, mechanical, aerospace, commercial industries, and recently in civil engineering. The paper presents two case studies of structural seismic vibration control using SMAs. The first one is a study of the SMA reinforced RC members. Two innovative applications in RC members, such as SMA-based Precast Concrete Frame Connection (SMA-PCFC), and SMA reinforced RC short column, were proposed. Moreover, the self-rehabilitation properties of SMAs-based Intelligent Reinforced Concrete Beams (SMA-IRCBs) were further experimentally investigated. The results show that SMAs can improve the mechanical properties of concrete members. SMA reinforced RC members have unique seismic performance compared to ordinarily steel reinforced concrete members. The second one is a study of the structural energy dissipation system using SMAs damping device. An innovative hybrid SMAs friction device (HSMAFD) which consists of pre-tensioned superelastic SMA wires and friction devices (FD) was presented. The results of cyclic tensile tests show that the HSMAFD exhibits stable large energy dissipation capacity and re-centering feature. The effectiveness of the HSMAFD in reducing horizontal response of structures subjected to strong seismic excitations was verified through shaking table tests carried out on a reduced-scale symmetric steel frame model with and without the HSMAFD.

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