Fault Diagnosis of Rotating Machines in Offshore Plant Based on Morlet Wavelet Transform

Burak OZTURK,KwangSik KIM,YooIl KIM,JangHyun LEE (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.2

The condition monitoring consists of a selection of measurable parameters such as vibration signals which correlate with the health or condition of a machine, and an interpretation of the collected data to determine the machinery fault existence and identify specific components (e.g. gear set, bearings) in the machine that are degrading. Many vibration and unbalanced signals of fault rotating machines in offshore plant have complex time-frequency characteristics. As a timefrequency analysis, wavelet transform is useful for locating transient events, discontinuities and patterns of these faults in non-stationary vibration data. The wavelet transformation can be an efficient way to detect the fault from the signal since the signal always includes the fault information about the rotating and reciprocating equipment inside. This paper introduces the faults diagnosis for offshore rotating machines by the application of Morlet wavelet transformation. Special attention is given to the vibratory and unbalanced faults, namely, rotating unbalance and resonance found in the rotating machine installed in offshore plant. Vibration signals recorded from accelerometer are processed by Morlet wavelet so that the both bearing and misalignment failure diagnosis. Thereafter, time-frequency contour map is introduced into fault diagnosis. The timefrequency contour map can easily show the power distribution of signal in time and frequency domain. Moreover, it is a good way to identify the faults involving a breakdown change. Several typical faults of rotating machines are detected by the time-frequency contour map obtained by the Morlet wavelet. The simulative results show that time-frequency contour map have the capabilities to identify the faults. This method also appeared to be an effective tool to diagnose and to discriminate the different types of machinery faults based on the unique pattern of the wavelet contours. This study shows that the proposed wavelet analysis method is promising to reveal machinery faults at early stage as compared to vibration spectrum analysis. A case study about the implementation of the continuous wavelet transform to the compressor fault diagnosis will be introduced. It is shown that the wavelet transform is a promising condition assessment of the compressors installed on ship and offshore.

Vibration analysis of asymmetric shear wall and thin walled open section structures using transfer matrix method

Kanat Burak Bozdogan,Duygu Ozturk 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.1

A method for vibration analysis of asymmetric shear wall and Thin walled open section structures is presented in this paper. The whole structure is idealized as an equivalent bending-warping torsion beam in this method. The governing differential equations of equivalent bending-warping torsion beam are formulated using continuum approach and posed in the form of simple storey transfer matrix. By using the storey transfer matrices and point transfer matrices which consider the inertial forces, system transfer matrix is obtained. Natural frequencies can be calculated by applying the boundary conditions. The structural properties of building may change in the proposed method. A numerical example has been solved at the end of study by a program written in MATLAB to verify the presented method. The results of this example display the agreement between the proposed method and the other valid method given in literature.

A method for static and dynamic analyses of stiffened multi-bay coupled shear walls

Kanat Burak Bozdogan,Duygu Ozturk 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.28 No.4

In this study an approximate method based on the continuum approach and transfer matrix method for static and dynamic analyses of stiffened multi-bay coupled shear walls is presented. In this method the whole structure is idealized as a sandwich beam. Initially the differential equation of this equivalent sandwich beam is written then shape functions for each storey is obtained by the solution of differential equations. By using boundary conditions and storey transfer matrices which are obtained by these shape functions, system modes and periods can be calculated. Reliability of the study is shown with a few examples. A computer program has been developed in MATLAB and numerical samples have been solved for demonstration of the reliability of this method. The results of the samples show the agreement between the present method and the other methods given in literature.

A method for static and dynamic analyses of stiffened multi-bay coupled shear walls

Bozdogan, Kanat Burak,Ozturk, Duygu Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.28 No.4

In this study an approximate method based on the continuum approach and transfer matrix method for static and dynamic analyses of stiffened multi-bay coupled shear walls is presented. In this method the whole structure is idealized as a sandwich beam. Initially the differential equation of this equivalent sandwich beam is written then shape functions for each storey is obtained by the solution of differential equations. By using boundary conditions and storey transfer matrices which are obtained by these shape functions, system modes and periods can be calculated. Reliability of the study is shown with a few examples. A computer program has been developed in MATLAB and numerical samples have been solved for demonstration of the reliability of this method. The results of the samples show the agreement between the present method and the other methods given in literature.

Vibration analysis of asymmetric shear wall and thin walled open section structures using transfer matrix method

Bozdogan, Kanat Burak,Ozturk, Duygu Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.1

A method for vibration analysis of asymmetric shear wall and Thin walled open section structures is presented in this paper. The whole structure is idealized as an equivalent bending-warping torsion beam in this method. The governing differential equations of equivalent bending-warping torsion beam are formulated using continuum approach and posed in the form of simple storey transfer matrix. By using the storey transfer matrices and point transfer matrices which consider the inertial forces, system transfer matrix is obtained. Natural frequencies can be calculated by applying the boundary conditions. The structural properties of building may change in the proposed method. A numerical example has been solved at the end of study by a program written in MATLAB to verify the presented method. The results of this example display the agreement between the proposed method and the other valid method given in literature.

Antithrombotic effect of epigallocatechin gallate on the patency of arterial microvascular anastomoses

Igde, Murat,Ozturk, Mehmet Onur,Yasar, Burak,Bulam, Mehmet Hakan,Ergani, Hasan Murat,Unlu, Ramazan Erkin Korean Society of Plastic and Reconstructive Surge 2019 Archives of Plastic Surgery Vol.46 No.3

Background Microvascular anastomosis patency is adversely affected by local and systemic factors. Impaired intimal recovery and endothelial mechanisms promoting thrombus formation at the anastomotic site are common etiological factors of reduced anastomosis patency. Epigallocatechin gallate (EGCG) is a catechin derivative belonging to the flavonoid subgroup and is present in green tea (Camellia sinensis). This study investigated the effects of EGCG on the structure of vessel tips used in microvascular anastomoses and evaluated its effects on thrombus formation at an anastomotic site. Methods Thirty-six adult male Wistar albino rats were used in the study. The right femoral artery was cut and reanastomosed. The rats were divided into two groups (18 per group) and were systemically administered either EGCG or saline. Each group were then subdivided into three groups, each with six rats. Axial histological sections were taken from segments 1 cm proximal and 1 cm distal to the microvascular anastomosis site on days 5, 10, and 14. Results Thrombus formation was significantly different between the EGCG and control groups on day 5 (P=0.015) but not on days 10 or 14. The mean luminal diameter was significantly greater in the EGCG group on days 5 (P=0.002), 10 (P=0.026), and 14 (P=0.002). Intimal thickening was significantly higher on days 5 (P=0.041) and 10 (P=0.02). Conclusions EGCG showed vasodilatory effects and led to reduced early thrombus formation after microvascular repair. Similar studies on venous anastomoses and random or axial pedunculated skin flaps would also contribute valuable findings relevant to this topic.

선박해양 시스템의 확률론적 위험도 평가 기법에 관한 연구

김광식(KwangSik KIM),이장현(JangSyun LEE),Burak Ozturk,황세윤(SeYun HWANG) (사)한국CDE학회 2013 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2013 No.1

해양에서 선박해양 구조물의 사고(Accident)는 예기치 못한 상황에서 작업자의 오류 또는 장비의 고장, 외부의 환경적 영향에 의해 일어난다. 이러한 사고를 예방하기 위해서는 사고 후 나타나는 증상에 대하여 해결책을 제시하는 것보다 근본적으로 내재되어 있는 발생 가능한 문제를 제시하고 이를 해결할 수 있는 방법론을 정립해야 한다. 또한 최근의 고부가가치 선박해양 구조물의 경우 복잡하고 다양한 시스템의 탑재로 인해 단순한 내부 부품의 고장으로 해당 구성품 또는 시스템에 막대한 여파를 미치게 될 수 있다. 따라서 이러한 위험(Risk)을 사고 발생 이전에 미리 예측하고 이에 대한 대책을 세우기 위해 위험도(Risk Assessment)평가 기법이 필요하게 된다. 본 연구에서는 기존의 위험도 평가기법에 확률론적인 방법론을 추가하여 각 시스템을 구성하는 구성품들에 대한 확률론적(Probabilistic) 위험도 평가 기법에 대하여 정의하고, 이를 통해 잠재된 위협을 예측(Risk Prediction)하고 예방하기 위한 방법론을 제시하고자 한다.